Fluoroelastomers Handbook: The Definitive User's Guide

Fluoroelastomers Handbook THE DEFINITIVE USER’S GUIDE AND DATABOOK

Albert L. Moore, Sc.D. Wilmington, Delaware

Copyright © 2006 by William Andrew, Inc. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the Publisher.

Plastics Design Library and its logo are owned by William Andrew, Inc.

Library or Congress Catalog Card Number: 2005023558 Library of Congress Cataloging-in-Publication Data Moore, Albert L. Fluoroelastomers handbook : the definitive user’s guide and databook / Albert L. Moore. p. cm. Includes bibliographical references and index. ISBN 0-8155-1517-0 (acid-free paper) 1. Elastomers—Handbooks, manuals, etc. 2. Fluorocarbons—Handbooks, manuals, etc. I. Title. TA455.E4M66 2005 620.1’94—dc22 2005023558

Printed in the United States of America This book is printed on acid-free paper. 10 9 8 7 6 5 4 3 2 1

Published by: William Andrew Publishing 13 Eaton Avenue Norwich, NY 13815 1-800-932-7045 www.williamandrew.com

NOTICE To the best of our knowledge the information in this publication is accurate; however the Publisher does not assume any responsibility or liability for the accuracy or completeness of, or consequences arising from, such information. This book is intended for informational purposes only. Mention of trade names or commercial products does not constitute endorsement or recommendation for their use by the Publisher. Final determination of the suitability of any information or product for any use, and the manner of that use, is the sole responsibility of the user. Anyone intending to rely upon any recommendation of materials or procedures mentioned in this publication should be independently satisfied as to such suitability, and must meet all applicable safety and health standards.

Contents

Series Editor’s Preface .......................................................................................................

ix

Preface ...............................................................................................................................

xi

Acknowledgments .............................................................................................................. xiii Part I. 1.

2.

Fundamentals .........................................................................................................................

3

1.1

Introduction .................................................................................................................

3

1.2

Scope: Fluorocarbon Elastomers ................................................................................

4

1.3

Nature of Fluoroelastomers .........................................................................................

5

1.4

Fundamental Properties .............................................................................................. 1.4.1 VDF Copolymers ............................................................................................ 1.4.2 TFE/Olefin Copolymers .................................................................................. 1.4.3 Perfluoroelastomers ....................................................................................... 1.4.4 Other Compositions .......................................................................................

6 6 6 6 6

1.5

Developmental History: Compositions, Cure Technology ...........................................

7

1.6

Major Uses of Fluoroelastomers .................................................................................

9

1.7

Producers of Fluoroelastomers ...................................................................................

11

References ..............................................................................................................................

12

Fluoroelastomer Composition and Properties .........................................................................

13

2.1

Major Families of Fluorocarbon Elastomers ................................................................

13

2.2

VDF/HFP/(TFE) Elastomers ........................................................................................

15

2.3

VDF/PMVE/TFE Elastomers .......................................................................................

17

2.4

TFE/PMVE Perfluoroelastomers .................................................................................

17

2.5

TFE/P Elastomers .......................................................................................................

19

2.6

E/TFE/PMVE Elastomers ............................................................................................

20

References ..............................................................................................................................

22

Part II. 3.

Fluoroelastomers Overview

Fluoroelastomers Technology

Fluoroelastomer Monomers ....................................................................................................

25

3.1

Introduction .................................................................................................................

25

3.2

Vinylidene Fluoride (VDF) ........................................................................................... 3.2.1 VDF Properties .............................................................................................. 3.2.2 VDF Synthesis ...............................................................................................

25 25 26

iii

iv

4.

Contents 3.3

Tetrafluoroethylene (TFE) ........................................................................................... 3.3.1 TFE Properties ............................................................................................... 3.3.2 TFE Synthesis ................................................................................................

26 27 27

3.4

Hexafluoropropylene (HFP) ........................................................................................ 3.4.1 HFP Properties .............................................................................................. 3.4.2 HFP Synthesis ...............................................................................................

29 29 29

3.5

Perfluoro(Methyl Vinyl Ether) (PMVE) ......................................................................... 3.5.1 PMVE Properties ........................................................................................... 3.5.2 PMVE Synthesis ............................................................................................

31 31 31

3.6

Olefins: Ethylene and Propylene .................................................................................

32

3.7

Cure-site Monomers .................................................................................................... 3.7.1 Types of Cure-site Monomers ........................................................................ 3.7.2 Halogenated Vinyl Monomers ........................................................................ 3.7.3 Functional Vinyl Ethers ..................................................................................

32 32 32 33

3.8

Safety Aspects of Monomer Handling ......................................................................... 3.8.1 Toxicity Considerations .................................................................................. 3.8.2 Flammability ................................................................................................... 3.8.3 Explosivity ......................................................................................................

33 33 34 34

References ..............................................................................................................................

35

Production of Fluoroelastomers ..............................................................................................

37

4.1

Introduction .................................................................................................................

37

4.2

General Process Description ......................................................................................

37

4.3

Free Radical Copolymerization ................................................................................... 4.3.1 General Reaction Scheme ............................................................................. 4.3.2 Copolymer Composition Relationships .......................................................... 4.3.3 Monomer Reactivity Ratios ............................................................................

38 38 39 40

4.4

Emulsion Polymerization ............................................................................................. 4.4.1 Emulsion Polymerization Kinetics .................................................................. 4.4.2 Continuous Emulsion Polymerization ............................................................ 4.4.3 Semibatch Emulsion Polymerization ..............................................................

41 42 49 53

4.5

Suspension Polymerization ......................................................................................... 4.5.1 Polymer Compositions ................................................................................... 4.5.2 Polymerization Mechanism and Kinetics ....................................................... 4.5.3 Reactor Design and Operation ...................................................................... 4.5.4 Polymerization Control ...................................................................................

59 61 61 63 63

4.6

Process Conditions and Polymer Characteristics ....................................................... 4.6.1 Molecular Weight Distribution ........................................................................ 4.6.2 End Groups .................................................................................................... 4.6.3 Composition and Monomer Sequence Distributions ......................................

65 65 68 68

4.7

Monomer Recovery .....................................................................................................

71

4.8

Isolation .......................................................................................................................

71

5.

Contents

v

4.9

Process Safety ............................................................................................................

73

4.10

Commercial Process Descriptions ..............................................................................

74

References ..............................................................................................................................

75

Cure Systems for Fluoroelastomers .......................................................................................

77

5.1

Introduction .................................................................................................................

77

5.2

VDF/HFP/(TFE) Copolymers: Diamine, Bisphenol, Peroxide ..................................... 5.2.1 Diamine Cure ................................................................................................. 5.2.2 Bisphenol Cure .............................................................................................. 5.2.3 Peroxide Cure ................................................................................................

77 77 78 83

5.3

VDF/PMVE/TFE Elastomers: Peroxide (Bisphenol) ....................................................

89

5.4

Perfluoroelastomers – Various Systems .....................................................................

93

5.5

TFE/Propylene Elastomers: Peroxide, Bisphenol .......................................................

95

5.6

Ethylene/TFE/PMVE Elastomers: Peroxide, Bisphenol ..............................................

99

References .............................................................................................................................. 101 6.

Processing of Fluoroelastomers ............................................................................................. 103 6.1

Introduction ................................................................................................................. 103

6.2

Mixing 6.2.1 6.2.2 6.2.3

6.3

Extrusion ..................................................................................................................... 106

6.4

Molding ........................................................................................................................ 6.4.1 General Considerations ................................................................................. 6.4.2 Compression Molding .................................................................................... 6.4.3 Transfer Molding ............................................................................................ 6.4.4 Injection Molding ............................................................................................

6.5

Calendering ................................................................................................................. 117

6.6

Other Processing Methods .......................................................................................... 119 6.6.1 Latex .............................................................................................................. 119 6.6.2 Thermoplastic Elastomers ............................................................................. 119

.......................................................................................................................... Compounding Ingredients .............................................................................. Mill Mixing ...................................................................................................... Internal Mixers ...............................................................................................

103 103 103 105 110 110 111 112 113

References .............................................................................................................................. 122

Part III. Environmental Resistance and Applications of Fluoroelastomers 7.

Fluid Resistance of VDF-containing Fluoroelastomers ........................................................... 125 7.1

Introduction ................................................................................................................. 125

7.2

Fluid Resistance Data ................................................................................................. 125

7.3

Discussion of Results .................................................................................................. 125

7.4

Fluid Service Recommendations ................................................................................ 126 Table 7.1 Chemical Resistance - FKM, VDF/CTFE, FKM/TFE Fluoroelastomers ..................................................................................... 127 Acetaldehyde to Butyl Cellosolve ............................................................. 127

vi

Contents

Table 7.2

Butyl Ether to Ethylene Trichloride ........................................................... Ethylenediamine to Lime Sulfur ............................................................... Lindol to Ramjet Fuel ............................................................................... Rapeseed Oil to Zinc Sulfate ................................................................... Fluid Resistance of Fluoroelastomer Families .........................................

138 150 165 178 192

References .............................................................................................................................. 193 8.

Fluid and Heat Resistance of Perfluoroelastomers ................................................................. 195 8.1

Introduction ................................................................................................................. 195

8.2

Fluid Resistance Data ................................................................................................. 195

8.3

Heat Resistance Data ................................................................................................. 195

8.4

Resistance to Special Environments ........................................................................... 196

8.5

Major Applications ....................................................................................................... Table 8.1 Chemical Resistance: FFKM Fluoroelastomer ......................................... Abietic Acid to Lithium Hypochlorite ......................................................... Lithium Nitrate to Zirconium Nitrate .......................................................... Table 8.2 Chemical Resistance ............................................................................... Table 8.3 Upper Continuous Service Temperatures for Perfluoroelastomer Compounds .............................................................................................. Table 8.4 Tecnoflon PFR: Heat Aging ..................................................................... Table 8.5 Perfluoroelastomer Black Compounds for Chemical Processing Industry .................................................................................................... Table 8.6 Perfluoroelastomer Compounds for Semiconductor Applications ............

196 198 198 212 223 223 224 224 225

References .............................................................................................................................. 226 9.

Fluid Resistance of TFE-olefin Fluoroelastomers ................................................................... 227 9.1

Introduction ................................................................................................................. 227

9.2

Fluid Resistance of TFE/Propylene Elastomers .......................................................... 9.2.1 TFE/P Dipolymer ............................................................................................ 9.2.2 TFE/P/VDF Terpolymers ................................................................................ 9.2.3 TFE/P/TFP Terpolymers ................................................................................ 9.2.4 Service Recommendations ............................................................................

227 227 233 234 236

9.3

Fluid Resistance of Ethylene/TFE/PMVE Elastomer .................................................. 9.3.1 Fluid Resistance Data .................................................................................... 9.3.2 Resistance to Oil Field Environments ............................................................ 9.3.3 Cure System Effects ...................................................................................... 9.3.4 Service Recommendations ............................................................................

236 237 237 237 237

References .............................................................................................................................. 239 10.

Fluoroelastomer Applications .................................................................................................. 241 10.1

Introduction ................................................................................................................. 241

10.2

Major End Uses ........................................................................................................... 241

10.3

Fabrication Methods .................................................................................................... 241

Contents 11.

vii

Compounds for O-rings and Molded Goods ........................................................................... 243 11.1

O-rings 11.1.1 11.1.2 11.1.3

........................................................................................................................ Specifications ................................................................................................. Compression Set Measurement .................................................................... VDF/HFP Dipolymer Compounds ..................................................................

243 243 243 245

11.2

VDF/HFP/TFE Compounds ......................................................................................... 253

11.3

VDF/PMVE/TFE Compounds ...................................................................................... 259

11.4

Seal Design Considerations ........................................................................................ 260

11.5

Additional Fluoroelastomer Molding Compounds ....................................................... 260

References .............................................................................................................................. 277 12.

Compounds for Auto Fuel Systems ........................................................................................ 279 12.1

Introduction ................................................................................................................. 279

12.2

Fuel Line Veneer ......................................................................................................... 280

12.3

Fuel Tank Components ............................................................................................... 287

12.4

Fuel Injector Seals ...................................................................................................... 288

12.5

Development Trends ................................................................................................... 289

References .............................................................................................................................. 290 13.

Compounds for Auto Power Train Service .............................................................................. 291 13.1

Introduction ................................................................................................................. 291

13.2

Oil Seal Requirements ................................................................................................ 291

13.3

Compounds for Oil Seals ............................................................................................ 294 13.3.1 FKM Elastomers ............................................................................................ 294 13.3.2 FEPM Elastomers .......................................................................................... 295

13.4

Compounds for Transmission Seals ........................................................................... 296

References .............................................................................................................................. 298 14.

Compounds for Power Plant Service ...................................................................................... 299 14.1

Introduction ................................................................................................................. 299

14.2

Flue Duct Expansion Joints ......................................................................................... 299

14.3

High-fluorine Terpolymers ........................................................................................... 299

References .............................................................................................................................. 302 15.

Other Fluoroelastomer Applications and Processing .............................................................. 303 15.1

Introduction ................................................................................................................. 303

15.2

Latex and Coatings ..................................................................................................... 303

15.3

Thermoplastic Processing ........................................................................................... 303

15.4

Fluoroelastomer Caulks .............................................................................................. 304

15.5

Processing Aids for Hydrocarbon Plastics .................................................................. 304

References .............................................................................................................................. 305 16.

Fluoroelastomer Safety and Disposal ..................................................................................... 307 16.1

Introduction ................................................................................................................. 307

16.2

Safety in Production .................................................................................................... 307

viii

Contents 16.3

Safety in Applications .................................................................................................. 308

16.4

Disposal ...................................................................................................................... 308

References .............................................................................................................................. 309

Appendix: PDL Ratings .................................................................................................... 311 Glossary ............................................................................................................................ 313 Trademarks ....................................................................................................................... 347 Index .................................................................................................................................. 349

Series Editor’s Preface The original idea for the Fluorocarbon Series was conceived in the mid 1990s. Two important rationales required the development of the collection. First, there were no definitive sources for the study of fluorinated polymers including the commercial products. A researcher seeking the properties and characteristics of fluorinated plastics did not have a single source to use as a reference. Information put out by commercial manufacturers of polymers have long been the sources of choice. Second, the post war generation (a.k.a., Baby Boomers) were beginning to retire, thus reducing the available knowledge in the industry and academia. Selection of the topics of the books has been based on the importance of the practical applications of the fluorinated polymers. Inevitably, a number of fluorinated macromolecule classes, that are important in their own rights, were left out of the series. In each case, the size of its audience was

simply too small to meet the economic requirements of publishing. The first two books of the series cover commercial fluoropolymers (ethylenic); the third book is focused on their applications in the chemical processing industries. The fourth book deals with fluoroelastomers, the fifth with fluorinated coatings and finishes, and the sixth book is about fluorinated ionomers, such as Nafion®. The authors of these handbooks are leaders in their fields who have devoted their professional careers to accomplish expertise. Each book is a product of decades of the author’s experience and several years of research into the available body of knowledge. Our hope is that these efforts will meet the needs of the people who work with fluorinated polymers for any reason. Future revisions are planned to keep this series abreast of progress in these fields. Sina Ebnesajjad

September 2005

Sina Ebnesajjad, Editor Plastics Design Library Dr. Sina Ebnesajjad is a senior technical consultant at the DuPont Company, where he has been in a variety of technical assignments since 1982. Dr. Ebnesajjad is the author of several handbooks on the science, technology, and applications of fluoroplastics published by William Andrew, Inc.

He is the Series Editor for the Fluorocarbon Handbook Series, which includes handbooks on fluoroplastics, fluoroelastomers, fluorinated coatings, and fluoroionomers. He has been the Editor of the Plastics Design Library since September, 2004.

Preface Fluoroelastomers based on copolymers of vinylidene fluoride and hexafluoropropylene and terpolymers containing tetrafluoroethylene, introduced commercially in the late 1950s and early 1960s, greatly extended the utility of elastomers. The heat and fluid resistance of fluoroelastomers is superior to that of other elastomers. Fluoroelastomer seals and other components have contributed to reliability, safety, and environmental protection in many areas including the aeronautical, automotive, oil, and chemical industries. Subsequent development of improved cure systems in the 1970s has led to better processing characteristics and enhanced properties of fluoroelastomers. New compositions, including specialty polymers based on perfluoro(methyl vinyl ether) and perfluoroelastomers based on copolymers of tetrafluoroethylene and perfluoro(alkyl vinyl ethers) with new cure systems imparting outstanding thermal and fluid resistance, have further extended service limits of elastomers. Various fluoroelastomer families are useful in long-term service in contact with a wide range of fluids up to 200°C to 300°C. New products with enhanced performance continue to be developed after more than forty-five years. As in the first two volumes on fluoroplastics in this handbook series, the aim of this volume is to compile a working knowledge of the chemistry and physics of fluoroelastomers, with descriptions of polymerization and production of polymers, processing and curing into fabricated products, and important applications. Emphasis is on technology currently used

commercially, along with some developments likely to become important in the future. The book focuses on providing a reference and a source for learning the basics for those involved in fluoroelastomer production and part fabrication, as well as for end users of fluoroelastomer parts and for students. The first part of this book is an overview of fluorocarbon elastomers, including descriptions of the nature of fluoroelastomers, properties of various compositions, developmental history, and major uses. Part II provides more details of fluoroelastomer technology, including monomer properties and synthesis, polymerization and production processes, cure systems, and processing methods. The last part covers fluid resistance of various fluoroelastomer families and major applications of fluoroelastomers. Since the main expertise of the author is in the area of fluoroelastomers’ synthesis, sections on polymerization include considerable theoretical detail. However, the main emphasis is on practical rather than theoretical technology. References at the end of each chapter serve as bibliography and additional reading resources. These references are not intended to be exhaustive; additional references in selected areas are available in a number of review articles. None of the views or information presented in this book reflects the opinions of any of the companies or individuals that have contributed to this book. Any errors are oversight on the part of the author. Albert L. Moore

August 2005

Acknowledgments Most of my knowledge and experience in the field of fluoroelastomers was acquired during a nearly forty-year career in elastomers research and development at DuPont and DuPont Dow Elastomers. I spent about twenty-five years in fluoroelastomers polymer development. Much of the technical information in this book is drawn from technical papers and product literature published by DuPont and DuPont Dow. I have drawn on knowledge obtained during discussions and collaboration with many of my former colleagues. As far as possible, I have tried to attribute credit for their contributions to individuals in the presentation of various topics in this book, but undoubtedly have missed some, for which I apologize. I have been fortunate in my career to have participated in the development of fluoroelastomers to take advantage of the bisphenol curing technology introduced in the early 1970s; in later development of specialty polymers for peroxide curing, and of bisphenol-curable polymers with improved processing characteristics; and still later with base-resistant fluoroelastomer compositions. All of this required close collaboration with colleagues in research, market technical groups, polymer production, and sales, along with advice from helpful customers. Many of these developments were worldwide efforts, involving research and development in the U.S., production in the U.S. and Europe, and technical service in the U.S., Europe, and Japan. It is impossible to list all those who contributed, but I will mention a number of colleagues with whom I worked closely. Walter W. Schmiegel has taught me much about curing elastomers over the years, allowing more rational design of polymers with good curing characteristics. S. David Weaver, Albertus van Cleeff, Lori D. Weddell, and Paul E. M. Wijnands have contributed much to my understanding of polymerization and production technology. Phan L. Tang, Donald F. Lyons, and Michael C. Coughlin, in addition to helpful discussions on fluoroelastomer polymerization, have provided much background material, including patents and publications, used in this book. John R. Richards and John P. Congalidis of DuPont have been helpful in clarifying many details of polymerization kinetics. Many colleagues in marketing technical groups have

been helpful to me in a number of developments over the years, including Albert L. Moran, David L. Tabb, John G. Bauerle, Ronald D. Stevens, and Stephen Bowers. In addition to collaboration, Eric W. Thomas and Theresa M. Dobel have provided me with a number of useful technical papers and reports. Fluoroelastomers’ suppliers have engaged in healthy competition over the years, from which we have all benefited by being pushed to develop improved products and processes for making them. DuPont and DuPont Dow have used continuous polymerization processes to make a wide range of polymer compositions and have developed cure systems for specialty fluoroelastomers. Dyneon (3M) has developed many bisphenol-curable products with excellent processing characteristics and properties. Daikin has contributed a “living radical” polymerization process to make peroxide-curable fluoroelastomers with excellent processing characteristics. Solvay Solexis and its predecessor companies Ausimont and Montefluos have developed efficient semibatch polymerization systems to make fluoroelastomers with carefully tailored architecture. Asahi Glass persisted in developing viable polymerization and curing systems for tetrafluoroethylene/propylene copolymers. In many cases, technical people have provided continuity in developments through significant changes in corporate structure. Much data in this book is excerpted from papers and product literature provided by these companies. I have tried to give adequate recognition of the accomplishments of the technical people involved. I have been supported in my career, and have been given considerable freedom in choosing directions for polymer and process development, by a number of managers in DuPont and DuPont Dow. Herman E. Schroeder was my research director for many years, including my first five-year assignment in fluoroelastomers, during which he supported a difficult development project involving considerable plant test work. Of several managers of fluoroelastomers research, Patrick S. Ireland, Subhash Gangal, and Dennis L. Filger have been particularly supportive. Fluoroelastomers Global Technical Director James D. MacLachlan and Technology Vice President Ashby L. Rice of DuPont Dow have supported

XIV

my work on this book, allowing me to start before retirement and to continue helpful contacts with colleagues after retiring. Sina Ebnesajjad, editor of the PDL Fluorocarbon Series, has provided invaluable help in guiding me through the writing of this volume. He provided much of the material in chapters on Fluoroelastomers Monomers and Processing of Fluoroelastomers, and led me to incorporate data from other books in the PDL Handbook Series in the Fluoroelastomers

FLUOROELASTOMERS HANDBOOK Applications section. I also wish to thank Millicent Treloar, Senior Acquisitions Editor of Plastics Design Library at William Andrew Publishing, for her support and suggestions. Many thanks are due to Jeanne M. Roussel and her staff at Write One for carefully handling the myriad details involved in converting my rough manuscript into a finished book. Finally, I am grateful for the continuing patience and support of my wife, Betty, during my career and during the writing of this book in the last few years.

Part I Fluoroelastomers Overview

1 Fundamentals 1.1

Introduction

Components fabricated from fluoroelastomers enhance reliability, safety, and environmental friendliness in such areas as automotive and air transportation, chemical processing industries, and power generation. Worldwide production of fluorocarbon elastomers was about 15,000 metric tons in 1999, but this modest volume of products is growing in importance for meeting more stringent performance requirements in these industries. Fluoroelastomers have outstanding resistance to most fluids at elevated temperatures, and are replacing other elastomers in applications where improved sealing performance is necessary. Automotive applications, mainly seals, hoses, and other small components in fuel and power train systems, account for over half of fluoroelastomers’ use. A wide range of fluoroelastomer products have been developed to meet performance requirements in many hostile environments, and to attain fabrication characteristics comparable to other elastomers. Examples of typical parts made from fluoroelastomers are shown in Fig. 1.1. O-ring seals account for about one third of fluoroelastomers’ usage. Shaft seals (about one quarter of usage) are of great im-

portance, especially for automotive power train applications. Other molded parts and extruded shapes (e.g., fuel hose) make up most of the rest of fluoroelastomers’ uses. The outstanding heat and oil resistance of fluoroelastomers compared to other elastomers is shown in Fig. 1.2, a chart developed by the American Society for Testing Materials (ASTM). Typical bisphenol-cured fluoroelastomers are given the ASTM classification HK. This means that for typical fluoroelastomer compounds aged 70 hours at 250°C, tensile strength changes no more than 30%, elongation-atbreak decreases less than 50%, and hardness changes no more than 15 points from original properties. Also after exposure to oil for 70 hours at 150°C, volume swell is no more than 10%. No other family of elastomers is close to this combination of heat and fluid resistance. This level of heat resistance translates to long useful service life of fluoroelastomers components, as shown in Fig. 1.3, with service life greater than 1000 hours at temperatures below 260°C, and short-term resistance to higher temperature excursions. Compared to other elastomers, fluoroelastomers exhibit much longer effective performance in seal applications at elevated temperatures, as illustrated in Fig. 1.4.

Figure 1.1 Typical fluoroelastomers parts. (DuPont Dow Elastomers.)

4

FLUOROELASTOMERS HANDBOOK

Figure 1.2 Heat and oil resistance of elastomers. (ASTM.)

Figure 1.3 Fluoroelastomer heat resistance. (DuPont Dow Elastomers.)

Figure 1.4 Retained o-ring sealing force. (DuPont Dow Elastomers.)

1.2

Only current commercial products are treated in detail. Some products previously sold, but now discontinued, are mentioned in this introductory chapter, but not in the more detailed sections that follow. Major topics covered include: compositions and characteristics of various fluoroelastomer families; major monomers, their synthesis and handling; polymerization and production technology; cure systems, cure-site monomers, and curative components; com-

Scope: Fluorocarbon Elastomers

This book emphasizes the technology and applications of fluorocarbon elastomers based on fluorinated organic polymers with carbon-carbon linkages in the backbone of the molecules. Fluoroelastomers with inorganic backbones, such as fluorosilicones and fluorinated polyphosphazenes, are described briefly.

1 FUNDAMENTALS

5

pounding and processing; and design for specific applications. Trends in product development, emerging uses, and methods of fabrication are discussed.

1.3

Nature of Fluoroelastomers

To exhibit elastomeric behavior, a polymer must be flexible and recover from substantial deformation at temperatures above about 0°C. This requires the polymer to be substantially amorphous, and above its glass transition temperature, so that chain segments have adequate mobility to allow the material to return to its original state after stress is removed.[1] Ordinarily the polymer is cross linked to form a threedimensional network with tie points between chains to minimize irreversible flow under stress. The driving force for recovery is the tendency of chain segments to return to the more disordered state with higher entropy when the stress causing a deformation is removed. Generally, fluorocarbon chains are relatively stiff compared to hydrocarbons, so fluoroelastomers exhibit rather slow relaxation and recovery from strain (i.e., leathery rather than highly

resilient behavior). Thus, most fluoroelastomers are used in static, rather than dynamic, applications. Fluorocarbon elastomers are copolymers made up of two or more major monomer units. One or more monomers give straight chain segments, which would tend to crystallize if long enough. A monomer with a bulky side group is incorporated at intervals to break up the crystallization tendency and produce a substantially amorphous elastomer. Commercial fluorocarbon elastomers are made by free radical polymerization of vinyl monomers. Monomers used in straight chain segments include: vinylidene fluoride (VDF), CH2=CF2; tetrafluoroethylene (TFE), CF2=CF2; and ethylene (E), CH2=CH2. Monomers that provide bulky side groups include hexafluoropropylene (HFP), CF2=CF–CF3, perfluoro(methyl vinyl ether) (PMVE), CF2=CF–O–CF3, and propylene (P), CH2=CH–CH3. The combinations of monomers used must produce substantially amorphous copolymers with glass transition temperatures low enough for elastomeric behavior at temperatures encountered in practical use. Monomer combinations used in several commercial product families are shown in Table 1.1. Major characteristics of these fluoroelastomer families are described in the following section.

Table 1.1 Major Monomers in Commercial Fluoroelastomers

Monomers with Bulky Side Groups

HFP

Monomers in Straight Chain Segments VDF

TFE

Example

E

Viton A Viton B

Viton GLT PMVE

Viton ETP Kalrez Perfluoroelastomer

P

Aflas 100 Aflas 200

6

1.4 1.4.1

FLUOROELASTOMERS HANDBOOK

Fundamental Properties VDF Copolymers

Copolymers of VDF with HFP in about 80/20 mole ratio comprise the highest volume fluoroelastomer family. These are readily cured with bisphenols to give excellent properties over a useful temperature range of –18°C to 250°C. These dipolymers are particularly useful for o-ring seals with good compression set resistance. TFE may be used to replace part of the VDF in terpolymers to get better fluid resistance with some sacrifice in low-temperature flexibility. Up to about 30% TFE may be incorporated without imparting excessive crystallinity in terpolymers. Elastomers with high fluorine content (low VDF levels) may contain cure-site monomers to allow peroxide-initiated free-radical curing. Specialty polymers with major monomers VDF, PMVE, and TFE have better low-temperature flexibility than the HFP family described above. Cure-site monomers must be incorporated to allow effective cross linking of these polymers, usually by free-radical cure systems. Products based on these compositions are becoming more important in automotive fuel system sealing applications, since good sealing performance is possible down to about –40°C. VDF-based fluoroelastomers are resistant to a wide range of fluids. However, because of the polar nature of VDF units, the polymers are soluble in low molecular weight esters and ketones, and vulcanizates are highly swollen by such polar solvents. Bisphenol-cured compounds contain relatively high levels of inorganic metal oxide and hydroxide, so these are susceptible to swelling and attack by hot aqueous fluids. Peroxide-cured compounds are more resistant to such aqueous environments. Strong inorganic base and organic amines at high temperatures also attack VDF-based polymers. In spite of these limitations, VDF-containing fluoroelastomers have performed well in severe environments, including automotive seals in contact with hot oils that contain considerable amine moieties.

1.4.2

nonpolar elastomers based on TFE and olefins have been developed. The major product here is a dipolymer with alternating TFE and propylene units. While difficult to process and cure, this polymer is used in wire and cable, oil field, and some automotive seal applications. TFE/P dipolymers have glass transition temperatures near 0°C, thus rather poor flexibility at low temperature. Also, their swell in hydrocarbons is high because of their low fluorine content. Terpolymers containing VDF have higher fluorine content and somewhat better low-temperature flexibility. These have better processing characteristics, but sacrifice some base resistance. A terpolymer of ethylene, TFE, and PMVE with cure sites allowing peroxide curing has excellent base resistance and fair low-temperature characteristics.[2] This specialty material is finding use in fluid environments where other fluoroelastomers have deficiencies. Ethylene has also been incorporated to partially replace VDF in a tetrapolymer with major monomers E/VDF/HFP/TFE and cure sites for peroxide curing.[3] The polymer, designed for enhanced resistance to base and amines, has been offered for use in oil seals for automotive power trains.

1.4.3

Perfluoroelastomers

To attain the fluid and thermal resistance of perfluorinated TFE-based plastics, two families of perfluoroelastomers have been developed. One is based on copolymers of TFE and PMVE, with various cure sites allowing a range of applications. The second family is based on a copolymer of TFE with a perfluoro(alkoxy alkyl vinyl ether) with a halogen cure site for peroxide curing. This polymer has better low temperature characteristics, but its upper service temperature is limited. Generally, parts made from perfluoroelastomers are used in extremely severe fluid service applications, where other elastomers are unsatisfactory. Main uses for perfluoroelastomer parts are in seals for chemical process and transportation industries, oil field service, aeronautical and aerospace, and semiconductor fabrication lines.

TFE/Olefin Copolymers

Because of the susceptibility of VDF/HFP-based fluoroelastomers to attack by polar fluids and bases,

1.4.4

Other Compositions

Fluoroelastomers based on copolymerization of VDF with chlorotrifluoroethylene (CTFE),

1 FUNDAMENTALS CF2=CFCl, have been offered commercially. In these copolymers, potential crystallinity from VDF sequences is avoided by incorporation of CTFE with its bulky chlorine side group. Two elastomeric copolymers, Kel-F® 5500 and 3700, containing 50 and 70 mole % VDF, were developed. These elastomers have good resistance to oxidizing acids. However, resistance to heat, fluids, and compression set is inferior to that of HFP-based fluoroelastomers.[4] The CTFE-based elastomeric products have been discontinued, but CTFE-based plastics, some with small amounts of VDF incorporated to reduce brittleness, are produced.[5] Two families of fluoroelastomers based on inorganic backbones have been offered commercially. Fluorosilicone and fluoroalkoxyphosphazene polymers have better low-temperature characteristics than fluorocarbon elastomers, but have lower resistance to high temperature. The flexible main chains of these polymers, allowing service at temperatures as low as –65°C, consist of alternating silicon and oxygen or phosphorus and nitrogen atoms. Fluorosilicone elastomers are similar to silicone elastomers, polydimethylsiloxane polymers, in which one methyl substituent on each silicone atom is replaced with a 3,3,3-trifluoropropyl group:[6] CH3 | –(Si–O)n– | CH2–CH2–CF3 Fluorosilicone processing and parts fabrication technology is basically the same as that of silicone elastomers, quite different from that of fluorocarbon elastomers. Fluoroalkoxyphosphazene elastomers have been withdrawn from the market. These elastomers were made from dichlorophosphazene polymers by displacing chlorine with fluorocarbon alkoxides:[7] O–CH2–CF3 | –(P=N)n– | O–CH2–CF2–CF2–CF3

7

1.5

Developmental History: Compositions, Cure Technology

Elastomeric copolymers of vinylidene fluoride and chlorotrifluoroethylene, made by M. W. Kellogg Co. under contract from the U.S. Army Quartermaster Corps, were described in 1955.[8] These fluoroelastomers had better heat and fluid resistance than elastomers available at the time. At DuPont, fluoroelastomer development work led by H. E. Schroeder centered on copolymerizing monomers that did not contain chlorine,[9] in order to obtain still better heat stability. A copolymer of VDF with hexafluoropropylene was described in 1956; details of its curing and properties were published soon afterward.[10] Polymer preparation was covered in a patent[11] issued later, after overcoming an interference proceeding brought by M. W. Kellogg. DuPont commercialized the VDF/HFP dipolymer in 1958 as Viton® A. A terpolymer with TFE, Viton B, was introduced in 1960; this has better heat and fluid resistance than the dipolymer.[12] The 3M Co., which had acquired Kellogg’s fluoropolymer assets, introduced a similar dipolymer under the trade name Fluorel®, under license from DuPont. With initial impetus provided by military applications, VDF/HFP fluoroelastomers quickly achieved commercial success, especially in molded seals. Faced with DuPont patents on VDF/HFP/(TFE) polymers, Montecatini-Edison S.p.A. in Europe developed Tecnoflon® dipolymers[13] and terpolymers[14] based on use of 1-hydropentafluoropropylene, CHF=CF–CF3, in place of hexafluoropropylene. With their lower fluorine content, these polymers had lower stability than HFP-based fluoroelastomers, so they were replaced with HFP polymers when the patents expired. In Japan, Daikin Kogyo started offering Dai-el® VDF/HFP/(TFE) fluoroelastomers in 1970 under license from DuPont. A Russian VDF/ HFP dipolymer, SKF-26,[15] has been consumed internally, with little offered on the world market. Polymer production processes differ among the suppliers. DuPont patents describe a continuous emulsion polymerization process with a continuous isolation process using centrifuges.[16] This allows high production rates for a given product to be sustained without interruption. Other suppliers use a semibatch polymerization process, in which water,

8

FLUOROELASTOMERS HANDBOOK

dispersing aids, initiator, and an initial monomer mixture are charged to the reactor. Then monomers are fed at the rate and composition corresponding to the polymer production. When the desired emulsion solids level is attained, monomer feed is stopped and the dispersion is discharged for polymer isolation. The high reactivity of the monomer mixture usually leads to the main limitation on rate being control of the heat of polymerization to maintain reactor temperature constant. During the 1960s, VDF-based fluoroelastomers were cured with diamines. The main curing agent used was hexamethylenediamine carbamate, +H N–(CH ) –NH–CO –. This blocked diamine 2 2 6 2 dehydrofluorinates HFP-VDF sequences to form double bonds and then the amine moieties add to the double bonds to form cross links. The HF formed is neutralized with magnesium oxide, forming water that is later removed in an oven postcure. This cure system is characterized by scorch—premature reaction at processing and forming temperatures—and relatively slow cure in the mold. With this cure system, mold sticking and fouling problems cause high scrap rates undesirable with such expensive materials. By 1970, DuPont and 3M developed better cure systems based on bisphenols, along with improved polymers designed to give better processing and performance with the new curatives. The bisphenol cure system has allowed development of products for fabrication of high-performance seals with much enhanced compression set resistance.[17] The preferred cross linking agent is Bisphenol AF, 2,2-bis(4-hydroxyphenyl)hexafluoropropane [I], with an accelerator such as benzyltriphenylphosphonium chloride [II].[18]

[I]

[II]

For optimum curing and compression set resistance, the polymers must have low ionic end-group levels.[19] A number of fluoroelastomers have been designed for excellent processing and curing with this system, and polymerization processes have been

developed to make such polymers efficiently.[20] Because of crosslicensing between DuPont and 3M of the preferred phosphonium accelerators, other producers were forced to use alternatives such as quaternary ammonium salts. Fluoroelastomer suppliers have developed a large number of bisphenolcurable products tailored for specific applications and customer processes, including precompounds of fluoroelastomers with bisphenols, accelerators, and processing aids. During the late 1970s, DuPont introduced peroxide-curable polymers to make vulcanizates less susceptible to degradation by steam and acid.[21] Bromine-containing monomers are incorporated to make sites reactive with free radicals at curing temperatures; the resulting radical sites on the chains then react with multifunctional radical traps to form a cross linked network.[22] This cure system has been particularly useful in high-fluorine polymers difficult to cure with bisphenols. Also, this curing technology was applied to VDF/PMVE/TFE polymers to allow development of specialty products with much improved low-temperature performance. Daikin introduced peroxide-curable fluoroelastomers with iodine on nearly all chain ends of polymers with very narrow molecular weight distribution made with a novel “living radical” semibatch polymerization process.[23] Compared to bromine-containing polymers, these iodine-containing polymers cured faster to give vulcanizates with better compression set resistance. DuPont later developed fluoroelastomers made in a continuous process to incorporate bromine cure sites along chains and iodine end groups.[24] These gave vulcanizates with better heat resistance than those from polymers containing iodine end groups as the only cure sites. To attain fluid and thermal resistance comparable to that of polytetrafluoroethylene plastics, DuPont scientists developed elastomeric copolymers of TFE with PMVE during the 1960s.[25] The perfluorinated polymer backbone imparts great resistance to heat and most fluids, but its inertness leads to difficulty in curing the elastomer. Considerable effort was put into development of suitable curesite monomers and cure systems that retain the desired properties of the perfluoroelastomer backbone. Of several cure systems studied by DuPont, those based on cure sites from perfluoroalkoxyvinyl ethers with functional groups gave outstanding high-temperature stability. Starting in 1972, DuPont offered

1 FUNDAMENTALS Kalrez® Perfluoroelastomer Parts for service in severe environments. Perfluoroelastomers with perfluorophenyl sites cured with bisphenols,[26] and those with perfluorocarbon nitrile sites cured with tetraphenyltin to get triazine cross links,[27] retain good properties for long periods at 288°C. Halogen cure sites from bromine-containing monomers or iodine end groups can be used with peroxide cure systems. Peroxide-cured vulcanizates have excellent fluid resistance, but no better thermal resistance than obtained with other fluoroelastomers. However, the bulk of perfluoroelastomer applications require excellent fluid resistance at temperatures below 200°C, within the capability of peroxide-cured components. In the early 1960s, workers at DuPont[28] and Asahi Glass[29] studied elastomeric copolymers of tetrafluoroethylene and propylene. These monomers have a strongly alternating tendency to free radical polymerization, so the copolymers contain about 50 mole % of each monomer. With glass transition temperature near 0°C, the copolymers have mediocre low-temperature flexibility. With their high propylene level and relatively low fluorine content, vulcanizates exhibit high swell in hydrocarbon fluids. However, these nonpolar elastomers are resistant to polar solvents and to organic and inorganic base. DuPont did not commercialize this elastomer family because of difficulty in polymerization and curing, combined with lack of interest by U.S. customers. Asahi Glass worked out semibatch polymerization conditions to get adequate molecular weight, and developed a heat treatment to get sites active enough to allow curing with peroxide and radical traps. Asahi Glass offers TFE/P elastomers as Aflas®. The largest market in Japan is for wire and cable applications; TFE/P

9 elastomers have better electrical resistivity than the more polar VDF-based fluoroelastomers. Terpolymers of TFE and propylene with VDF have also been developed. These may be cured with diamines[30] or bisphenols[31] to obtain better low-temperature characteristics and hydrocarbon resistance, but somewhat lower base resistance than TFE/P dipolymer products. To get a combination of properties better than those of TFE/P polymers, DuPont workers developed elastomeric terpolymers of TFE and PMVE with ethylene.[32] These products are resistant to base and most fluids, and have better low-temperature characteristics than TFE/P copolymers.

1.6

Major Uses of Fluoroelastomers

Fluoroelastomers are used mainly in seals and barrier layers subjected to environments too severe for other elastomers. Fluoroelastomer components have long service life at temperatures above 150°C, and some specialty perfluoroelastomer parts can withstand sustained temperatures above 300°C. Fluoroelastomers are resistant to a wide range of fluids, so long as proper polymer compositions and cure systems are chosen for particular environments. The low permeability and service reliability of fluoroelastomers have resulted in their increasing use to reduce emissions and releases in the chemical processing and transportation industries. Automobile applications comprise the largest fluoroelastomers market, with components used in drive train and fuel handling systems (see Fig. 1.5).

Figure 1.5 Fluoroelastomer components in auto fuel systems. (DuPont Dow Elastomers.)

10

FLUOROELASTOMERS HANDBOOK

Glass transition temperatures of fluoroelastomers are in the range 0°C to –30°C, generally higher than those of hydrocarbon elastomers. At moderate temperatures, fluoroelastomers recover relatively slowly from imposed strain, and are not suitable for many dynamic applications. Most fluoroelastomers are used as static seals or barriers in applications where rapid recovery from strain is not necessary, (e.g., in o-rings, gaskets, and hoses). Even in shaft seals, the designs are such that fluoroelastomers’ compositions do not need to exhibit rapid recovery, and thus can function well. O-ring seals comprise the largest volume product form of fluoroelastomers. One of the initial uses of fluoroelastomers was in aircraft and aerospace seals, especially in engines and fuel handling systems. In automobiles, fluoroelastomer o-rings are particularly important as fuel injector seals. A variety of fluoroelastomer polymer compositions are used for o-ring seals in the chemical processing and chemical transportation industries. The bulk of o-ring seals are made from bisphenol-cured VDF/HFP dipolymers, formulated for the best long-term resistance to compression set. However, some environments require better long-term resistance to aggressive fluids under severe conditions, so o-ring seals made of more resistant fluoroelastomer compositions are becoming more important. These include high-fluorine terpolymers of VDF/HFP/TFE and VDF/ PMVE/TFE, perfluoroelastomers, TFE/propylene elastomers, and ethylene/TFE/PMVE elastomers. Fluoroelastomer shaft seals have found increasing use, especially in automotive drive train systems, where temperatures are increasing and lubricants have been formulated for better performance. Seal lifetime requirements have become more stringent—automobile shaft seals are expected to last for more than 100,000 miles without significant leakage. Fluoroelastomer suppliers have been particularly challenged to develop materials for low-cost shaft seals resistant to modern lubricants at temperatures exceeding 160°C. Dispersants, antioxidants, and other additives in these lubricants generate amines which attack VDF-containing fluoroelastomers at high temperature and cause failure by embrittlement or network breakdown. Various low-VDF or no-VDF fluoroelas-

tomers are being evaluated for the most severe uses. The intricate shapes of shaft seals (see Fig. 1.6), along the requirement for good adhesion of rubber to metal insert, necessitate design of the base polymers and compounds for excellent processing characteristics (e.g., excellent mold flow, rapid cure, and clean demolding). Gaskets and packing make up a significant market for fluoroelastomers for sealing against fluids at high temperatures for extended periods. Lower-performance elastomers are being replaced, especially in automotive and chemical process seals, to attain the better reliability and service lifetimes required for protection of the environment. As part of efforts to reduce automotive fuel emissions, fluoroelastomer hose components have become important. One of the first fuel-system uses for fluoroelastomers was in composite fuel-line hose, in which a thin veneer of extruded fluoroelastomer serves as an inner barrier layer. Originally VDF/HFP dipolymer was used, but lower emission standards have necessitated use of high-fluorine terpolymers or thicker veneers. Because of the resulting higher cost of such fluoroelastomer hose, some of this application has been taken over by thermoplastics. However, molded hose and other components, especially in the fuel tank, are being fabricated of fluoroelastomers. To reduce pollution in the electrical generation industry, fluoroelastomer-coated fabric is used in expansion joints for exhaust ducts that handle hot, acidic flue gas from desulfurization systems. Special fluoroelastomer compounds are used in oil and gas production, especially in deep wells where elastomer

Figure 1.6 Shaft seal cross section. (CR Industries.)

1 FUNDAMENTALS

11

components must withstand corrosive fluids at high temperature.

1.7

Producers of Fluoroelastomers

Major producers of fluoroelastomers are listed in Table 1.2, in order of their worldwide market share. Also listed are trade names and locations of corporate headquarters and polymer manufacturing facilities. All of these companies produce a wide range of fluoroelastomer and perfluoroelastomer compositions, except for Asahi Glass, which makes TFE/ propylene polymers only (also marketed by Dyneon and DuPont Dow). DuPont Dow Elastomers LLC, a joint venture of DuPont and Dow Chemical formed in 1996, took over the former Viton® Fluoroelastomers and Kalrez® Perfluoroelastomer Parts businesses of DuPont. With the breakup of the joint venture in mid-2005, the fluoroelastomers business became part of DuPont Performance Elastomers, a wholly owned DuPont subsidiary. Dyneon is a wholly owned

subsidiary of 3M Company; the trade name for its fluoroelastomers products was changed from Fluorel to Dyneon® in 1999. Solvay Solexis was formed in 2003 after the Solvay Group acquired Ausimont and joined these assets with Solvay fluoropolymer activities. Ausimont was formerly Montefluos, a part of the Montedison group. All the fluoroelastomers producers are part of, or allied with, fluoroplastics and fluoromonomers businesses. Other fluoroelastomer producers sell little or no product on the open international market. Nippon Mektron Ltd. makes fluoroelastomers and perfluoroelastomers for the Freudenberg-NOK Group (FNGP), major worldwide manufacturers of seals. Suppliers of materials used mainly in their own countries, with little export sales, include 3F Company, Shanghai, China, and KCCE, Kirovo-Chepetsk, Russia. The S. V. Lebedev Synthetic Rubber Institute (VNIISK) in St. Petersburg has developed most of the fluoroelastomers made in Russia under the trade name Fluorelast. A large number of companies make seals, molded and extruded parts, and other fabricated components from fluoroelastomers.

Table 1.2 Fluoroelastomers Producers and Trade Names

Company and Headquarters

Trade Names

Production Locations

DuPont Performance Elastomers LLC Wilmington, DE

Viton, Kalrez

Deepwater, NJ Dordrecht, Netherlands

Dyneon LLC Oakdale, MN

Dyneon

Decatur, AL Zwijndrecht (Antwerp), Belgium

Solvay Solexis SpA Bollate, Italy

Tecnoflon

Spinetta-Marengo (Milan), Italy Thorofare, NJ

Daikin Industries Ltd. Osaka, Japan

Dai-el

Settsu (Osaka), Japan

Asahi Glass Co. Ltd. Tokyo, Japan

Aflas

Ichihara (Chiba), Japan

12

FLUOROELASTOMERS HANDBOOK

REFERENCES 1. W. W. Schmiegel, Organic Fluoropolymers, in: Chemistry of Organic Fluorine Compounds II, ACS Monograph 187:1111 (1995) 2. A. L. Moore, U.S. Patent 4,694,045, Base Resistant Fluoroelastomers, assigned to DuPont (September 15, 1987) 3. M. Albano et al., U.S. Patent 5,354,824 (May 22, 1992) 4. R. G. Arnold, A. L. Barney, and D. C. Thompson, Fluoroelastomers, in: Rubber Chemistry and Technology, 46:625 (1973) 5. D. P. Carlson and W. W. Schmiegel, Organic Fluoropolymers, in: Ullman’s Encyclopedia of Industrial Chemistry, A11:411 (1988) 6. Ibid., 418 7. H. R. Allcock et al., Inorganic Chemistry, 5:1709 (1966) 8. M. E. Conroy et al., Rubber Age, 76:543 (1955) 9. H. E. Schroeder, Facets of Innovation (Goodyear Medal address), in: Rubber Chemistry and Technology, 57:G94 (1984) 10. S. Dixon, D. Rexford, and J. S. Rugg, Industrial and Engineering Chemistry, 49:1687 (1957) 11. D. R. Rexford, U.S. Patent 3,051,677, assigned to DuPont (1962) 12. J. R. Pailthorp and H. E. Schroeder, U.S. Patent 2,968,649, assigned to DuPont (1961) 13. D. Sianesi, C. Bernardi, and A. Regio, U.S. Patent 3,331,823 (1967) 14. D. Sianesi, C. Bernardi, and G. Diotalleri, U.S. Patent 3,335,106 (1967) 15. S. V. Sokolov, Fluororubbers, in: Synthetic Rubber, I. V. Garmonova, ed., Leningrad (1983) 16. F. V. Bailor and J. R. Cooper, U.S. Patent 3,536,683, assigned to DuPont (October 27, 1970) 17. R. G. Arnold et al., op. cit., 631. 18. A. L. Moran and D. B. Pattison, Rubber World, 103:37 (1971) 19. E. K. Gladding and J. L. Nyce, U.S. Patent 3,707,529, assigned to DuPont (December 26, 1972) 20. A. L. Moore, U.S. Patent 3,839,305, assigned to DuPont (October 1, 1974) 21. H. E. Schroeder, op. cit., G96 22. D. Apotheker and P. J. Krusic, U.S. Patent 4,214,060, assigned to DuPont (1980) 23. M. Tatemoto, T. Suzuki, M. Tomoda, Y. Furukawa, and Y. Ueta, U.S. Patent 4,243,770 (1980) 24. A. L. Moore, U.S. Patents 4,948,852 (1990), 4,973,633 (1990), 5,032,655 (1991), and 5,077,359 (1991) 25. G. A. Gallagher, U.S. Patent 3,069,401, assigned to DuPont (1962) 26. G. H. Kalb, A. A. Khan, R. W. Quarles, and A. L. Barney, ACS Advances in Chemistry Series, No. 129, pp. 13–26 (1973) 27. A. F. Breazeale, U.S. Patent 4,281,092, assigned to DuPont (July 28, 1981) 28. W. R. Brasen and C. S. Cleaver, U.S. Patent 3,467,635, assigned to DuPont (1969) 29. Y. Tabata, K. Ishigure, and H. Sobue, Journal of Polymer Science, Part A-2, 2235 (1964) 30. J. R. Harrell and W. W. Schmiegel, U.S. Patent 3,859,259, assigned to DuPont (1975) 31. G. Kojima and H. Wachi, International Rubber Conference, p. 242, Kyoto, Japan (1985) 32. A. L. Moore, Elastomerics, 118(No. 9):14–17 (1986)

2 Fluoroelastomer Composition and Properties 2.1

Major Families of Fluorocarbon Elastomers

fluoride, tetrafluoroethylene, and ethylene) would contribute to crystallinity if incorporated in sufficiently long sequences. The other three monomers [hexafluoropropylene, perfluoro(methyl vinyl ether), and propylene] have bulky side groups that hinder crystallization and allow synthesis of amorphous elastomers. VDF and PMVE contribute to low glasstransition temperature (Tg) and thus to good lowtemperature flexibility. All the fluoromonomers impart good resistance to hydrocarbons. VDF is a polar moiety, especially when incorporated adjacent to perfluorinated monomer units, so it contributes to swelling in contact with low molecular weight polar solvents and is susceptible to attack by base. Ethylene and propylene units contribute to swelling in contact with hydrocarbons, but are resistant to polar solvents and base. Several families of commercial fluoroelastomers have been designed with various combinations of these major monomers to get characteristics necessary for successful performance in wide ranges of applications and environments. Dipolymers of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) make up the largest volume of fluoroelastomers sales. Only one composition (VDF/HFP about 60/40 weight percent or 78/22 mole %, 66% fluorine) is of commercial importance, but it is offered in a wide range of viscosities and in numerous formulations tailored for

Fluorocarbon elastomers are copolymers of various combinations of monomers. Composition can be chosen to get a desired combination of properties. The main characteristics affected by composition are fluid resistance, stability at high temperatures, and flexibility at low temperatures. Ease of processing and curing also vary with composition. The situation with fluoroelastomers is analogous to that of several hydrocarbon-based elastomers in which composition determines the trade-off between oil resistance and low-temperature characteristics. For example, in the nitrile rubber family (NBR, copolymers of butadiene and acrylonitrile), higher acrylonitrile content enhances oil resistance, but gives poorer lowtemperature flexibility. The same trade-off exists for acrylate content of elastomers based on copolymers of ethylene and ethyl acrylate. Chlorine content exerts similar effects in chlorinated polyethylene elastomers. The range of property variation that can be attained by varying composition is much greater for fluoroelastomers than for the hydrocarbon-based elastomer families. Effects of various major monomers on important fluoroelastomer characteristics are indicated in Table 2.1. Three of the monomers (vinylidene

Table 2.1 Fluoroelastomer Characteristics Imparted by Major Monomers

Contribution Monomer

Formula

Resistance to: Tg

Crystallinity

Hydrocarbons

Polar Solvents

Base

VDF

CH2= CF2

↓

↑

↓

↓

↓

HFP

CF2= CF–CF3

↑

↓

↑

↑

−

TFE

CF2= CF2

↑

↑

↑

↑

−

PMVE

CF2= CF–O–CF3

↓

↓

↑

↑

−

E

CH2= CH2

↑

↑

↓

↑

↑

P

CH2= CH–CH3

↑

↓

↓

↑

↑

14 specific applications. Other dipolymer compositions can be made, but higher VDF content leads to significant crystallinity, while lower VDF levels give much higher glass-transition temperatures, both detrimental to low-temperature flexibility. Terpolymers of VDF and HFP with tetrafluoroethylene (TFE) afford a better way to get enhanced fluid resistance without such severe effects on low-temperature characteristics. Useful terpolymers can be made with VDF content as low as about 30% to get fluoroelastomers with higher fluorine content (up to about 71%) and better fluid resistance. Most curing of these elastomers is based on the versatile bisphenol cure system, but some TFE-containing polymers are designed for free radical (peroxide) curing. A family of fluoroelastomers growing in importance because of better low-temperature characteristics is based on use of perfluoro(methyl vinyl ether) [PMVE] in place of HFP in copolymers with VDF and TFE. Incorporation of a small amount of cure site is necessary to facilitate curing with peroxide systems. These PMVE-containing elastomers are useful at temperatures 10°C to 20°C lower than possible with HFP-containing polymers with comparable VDF content. Figure 2.1 shows trends in fluid resistance and low-temperature flexibility for vulcanizates of VDF/HFP/TFE and VDF/PMVE/

FLUOROELASTOMERS HANDBOOK TFE elastomers with varying fluorine (VDF) content. All these elastomers are resistant to a wide range of fluids. However, for this comparison, a fuel mixture (M15 Fuel) containing 15% methanol and 85% standard hydrocarbon Fuel C was chosen to show the relatively large increase in volume swell with higher VDF content (lower fluorine content). The measure of low-temperature characteristics shown, TR-10, is a test carried out on cured strips of elastomer. The specimen is stretched, locked in the elongated condition, and cooled to very low temperature; then the specimen is released, and allowed to retract freely while raising the temperature at a uniform rate. TR-10 is the temperature at which the specimen has retracted 10%. For a vulcanizate of medium hardness, TR-10 is close to the glass transition temperature of the base polymer. TR-10 decreases with increasing VDF content, and is much lower for PMVE-based fluoroelastomers. Perfluoroelastomers, copolymers of TFE with PMVE or a perfluoro(alkoxyalkyl vinyl ether), have excellent resistance to most fluids. With properly designed cure systems, TFE/PMVE elastomer vulcanizates have long service life at temperatures up to 300°C. Perfluoroelastomer parts can be designed for use in extreme environments that would destroy other elastomers.

Figure 2.1 Fluid resistance and low-temperature flexibility of VDF-based fluoroelastomers.[6]

2 FLUOROELASTOMER COMPOSITION AND PROPERTIES Two families of fluoroelastomers are based on copolymerization of fluoromonomers with ethylene or propylene. Copolymers of TFE and propylene are resistant to polar fluids and base, but susceptible to high swell in hydrocarbons. Incorporation of VDF improves oil resistance at the expense of some base resistance. Ethylene may be used in place of VDF in copolymers with TFE and PMVE to get excellent resistance to most solvents and polar fluids, including base and amines. Determination of fluoroelastomer composition is rather difficult. VDF/HFP dipolymer composition and monomer sequencing were determined by 19 F nuclear magnetic resonance (NMR).[1] A typical spectrum is shown in Fig. 2.2. In studies related to curing, W. W. Schmiegel has interpreted the more complicated VDF/HFP/TFE and VDF/PMVE/TFE terpolymer spectra.[2] For quantitative analysis of terpolymers, VDF may be determined by 1H NMR; then TFE and HFP or PMVE can be calculated from 19F NMR on the same polymer. In practice, NMR analysis is not sufficiently rapid or precise for routine use in polymerization plant control. Elemental analyses for C, H, and F are of limited utility, with fluorine determination being particularly susceptible to bias errors because of interaction of fluorine with laboratory glassware used in the analysis. (Values of fluorine content of fluoroelastomers reported by suppliers are based on calculations from overall monomer composition, rather than direct analysis.) Usually a number of well characterized copolymers of varying composition are used as standards for

Figure 2.2 19F NMR spectrum, VDF/HFP dipolymer.[2]

15 calibration of suitable Fourier Transform Infrared (FTIR) methods for the various fluoroelastomer families. Careful monomer mass balances around wellcontrolled laboratory polymerization reactors allow preparation of precise composition standards. Even so, some inconsistencies probably exist in reported values of fluorine content by different fluoroelastomer suppliers.

2.2

VDF/HFP/(TFE) Elastomers

A ternary plot[3] of all the possible polymer compositions from VDF, HFP, and TFE monomers is shown as Fig. 2.3, based on polymer synthesis and thermal characterization studies by the author. A number of VDF/HFP and VDF/TFE dipolymers and VDF/HFP/TFE terpolymers were made by emulsion polymerization in a continuous reactor, with compositions determined by monomer mass balances. Glass transition temperatures, melting points, and heats of fusion were determined by differential scanning calorimetry (DSC). Polymers were designated as elastomers if they had glass transition temperatures less than 20°C, crystalline melting points below 60°C, and heats of fusion below 5 joules per gram. The Tg limit set the high-HFP, low-VDF boundary, and the limits on crystallinity set the lowHFP, high-VDF or high-TFE boundary of the elastomeric range. The large region of high-VDF or highTFE plastics was characterized by high crystallinity (heats of fusion above 10 J/g) with melting points

16

FLUOROELASTOMERS HANDBOOK be obtained with peroxide-cured, high-fluorine types. These elastomers are not recommended for contact with low molecular weight ketones and esters (e.g., acetone or ethyl acetate) because of excessive swell. They are attacked by strong bases and concentrated amines at high temperature.

Table 2.2 VDF Fluoroelastomers - Composition, Tg

Type

% VDF

%F

Tg, °C

60

66

-18

AL

60

66

-21

BL

50

68

-18

B

45

69

-13

F

36

70

-8

VDF/HFP A VDF/HFP/TFE Figure 2.3 A ternary plot of all the possible polymer compositions from VDF, HFP, and TFE monomers.

above 120°C. These plastics have been described in the first two volumes of this handbook series.[4] The intermediate region labeled “elastoplastics” comprises polymers with considerable crystallinity melting at 60°C–120°C. These are rather stiff polymers with higher modulus than elastomers. They do not generally have adequate mechanical properties for commercial usefulness. The unlabeled region of highHFP compositions would have high Tg and low crystallinity; these are impractical to make because of poor polymerizability of high-HFP mixtures. Approximate compositions of commercial elastomeric products are shown on the ternary diagram, with letters denoting the various composition families using the Viton® type nomenclature developed by DuPont Dow Elastomers, as listed in Table 2.2. HFP levels in these commercial polymers were chosen to be high enough to avoid significant crystallinity, but were kept as low as possible to get reasonable low-temperature flexibility and processing characteristics. All these polymers can be cured with the versatile bisphenol cure system, which gives good processing characteristics and excellent vulcanizate properties. These fluoroelastomers are recommended for use in contact with aromatic hydrocarbons, chlorinated solvents, gasoline, motor oils, and hydraulic fluids. Products with high fluorine content are useful in contact with alcohol-containing fuels. Good resistance to hot water, steam, and acids can

VDF/PMVE/TFE GLT

54

64

-29

GFLT

36

67

-23

Figure 2.4 Ternary diagram showing all the possible polymer compositions based on VDF, PMVE, and TFE monomers.

2 FLUOROELASTOMER COMPOSITION AND PROPERTIES

2.3

VDF/PMVE/TFE Elastomers

The ternary diagram, Fig. 2.4, shows all the possible polymer compositions based on VDF, PMVE, and TFE monomers. The elastomeric range is much more extensive for this system, since amorphous polymers with low Tg can be obtained with low, or no, VDF content. Two VDF-containing commercial products, Viton GLT and GFLT, are indicated on the ternary plot and listed in Table 2.2. The terpolymers cannot be cured satisfactorily with bisphenols; instead, small amounts of bromine or iodine cure sites are incorporated to allow peroxide curing. Recently, a new class of VDF/PMVE/TFE products has been developed, with incorporation of a reactive cure-site monomer to allow bisphenol curing in special formulations.[5] Processing of the bisphenol-curable products is significantly improved over that of peroxide-cured versions, especially in facilitating efficient molding with extremely low mold fouling and parts rejection rates. Fluid resistance depends on VDF content, similar to that of HFP-containing elastomers. However, the PMVE-based fluoroelastomers have much better low-temperature characteristics than those of HFP-based polymers, as shown in Figs. 2.1, and 2.5, a plot of Tg versus VDF content.

Figure 2.5 VDF-based fluoroelastomers: Tg vs % VDF.

17 Low-temperature characteristics of fluoroelastomers are often assessed by relatively simple tests, such as Tg of raw polymer, TR-10 of cured strips, or brittle point (temperature at which a sample cracks on bending). Such tests provide only a rough indication of usefulness of the materials in actual applications. While difficult and time-consuming to measure precisely, o-ring seal performance at low temperature has been evaluated for a number of fluoroelastomers.[6] Using a specially designed o-ring seal rig, the temperature at which nitrogen under pressure started to leak appreciably was recorded. Seal test results are shown in Fig. 2.6, in comparison to screening tests on fluoroelastomers of various compositions. Minimum temperatures for effective sealing are significantly lower than Tg or TR-10 values, and generally somewhat higher than brittle points.

2.4

TFE/PMVE Perfluoroelastomers

Copolymers of TFE with 25–40 mole % perfluoroalkyl vinyl ether are elastomeric. With properly chosen cure systems, they may have oxidative, chemical, and thermal resistance approaching that of polytetrafluoroethylene plastics. Copolymers of

18

FLUOROELASTOMERS HANDBOOK

Figure 2.6 Low-temperature properties of VDF-based fluoroelastomers.[6]

TFE and PMVE containing about 45% PMVE are amorphous and have glass transition temperatures of about –4°C, as shown as Kalrez in Fig. 2.4 and FFKM in Fig. 2.5. Cure systems developed by DuPont[7] use perfluorinated cure-site monomers to get vulcanizates stable for extended service at 300°C and resistant to most aggressive fluids. The most successful of these cure sites are formed by copolymerizing about 1 mole % of functional vinyl ether of general structure: CF2=CF–O–RFX, with RF denoting perfluoroalkylene and X a functional group, OC6F5 or O(CF2)nCN. Copolymers with perfluorophenyl cure sites are crosslinked with a specially designed bisphenol system. Those with pendant cyano groups are cured using tetraphenyltin as catalyst to form highly stable triazine crosslinks.[8] Relatively long press cures followed by long postcures in an oven under nitrogen are necessary to attain the final stable crosslink structures of the finished parts. These copolymers are made by emulsion polymerization using an inert perfluorinated soap. Reaction temperatures must be kept low to get intact

incorporation of the functional vinyl ether cure-site monomers. The persulfate-sulfite redox initiation system used by DuPont for the first perfluoroelastomer products gave predominantly sulfonate end groups which form ionic associations stable at temperatures normally used for mixing, extruding, and forming molded shapes. Thus they could not be processed readily like other fluoroelastomers. Because of this, DuPont developed specialized handling methods for making parts (mainly o-ring seals) sold as Kalrez Perfluoroelastomer Parts®. Later products developed by DuPont Dow and other producers are made with other initiator systems to get more tractable elastomers processible by conventional means. Iodine or bromine cure sites have been incorporated in perfluoroelastomers by use of suitable comonomers or transfer agents. These polymers can be cured with conventional peroxide systems using multifunctional crosslinking agents such as triallylisocyanurate. The resulting vulcanizates retain most of the fluid resistance of the perfluoroelastomer parts

2 FLUOROELASTOMER COMPOSITION AND PROPERTIES previously described, but peroxide-cured products have lower thermal resistance (maximum long term service temperature about 230°C) and are susceptible to attack by strong oxidizing agents. To get better low-temperature flexibility (Tg about –20°C), Daikin[9] developed peroxide-curable perfluoroelastomers based on TFE copolymerization with complex vinyl ethers of structure CF2=CF[OCF 2– CF(CF3)]nOCF2–CF2–CF3 with n = 1–4. These products are sold as raw polymer for conventional processing by parts fabricators. In spite of high cost, perfluoroelastomers are used in many applications where other materials are unsatisfactory. In the chemical processing industries, perfluoroelastomers provide reliable seals against most fluids over a wide range of conditions. Such high performance results in lower costs for seal replacement and in avoiding emission of hazardous materials. Perfluoroelastomers are finding increased use as seals in semiconductor fabrication lines, since these materials withstand exposure to plasmas and other aggressive fluids at high temperatures without contamination of the semiconductor parts. One of the first uses of perfluoroelastomers was in parts to protect electrical components used in oil field exploration and production. These parts withstand the high temperatures and pressures involved in deep wells, as well as aggressive sour gas and corrosive fluids. Perfluoroelastomer seals are used in aerospace and in military and commercial aircraft. Because of their inertness and cleanliness, perfluoroelastomers are approved for seals in the food and pharmaceutical industries. To assure adequate performance of perfluoroelastomers seals at temperatures up to 300°C above ambient, special design considerations must be taken into account. Perfluoroelastomers have high coefficients of thermal expansion, and their compounds contain relatively low levels of filler, so seal groove geometry has to allow adequate space for the elastomer to expand at high temperatures. If the grooves are too small, seal failure may occur by extrusion of the elastomer out of the groove, or by cracking due to local strains exceeding the elongation-at-break of the elastomer. DuPont Dow Elastomers offers finite element analysis to fabricators as an aid to designing proper shapes of the perfluoroelastomer parts and the seal apparatus for specific applications.

19

2.5

TFE/P Elastomers

Because of the strong alternating tendency of TFE and propylene monomers in free radical polymerization, the dipolymers vary little in composition. Commercial TFE/P elastomers are made slightly rich in TFE (about 53 mole %) to avoid contiguous propylene units that would tend to give lower thermal stability. The regular alternating chain structure, –[CF2–CF2–CH2–CH(CH3)]n–, is elastomeric because the random orientation of methyl groups from nonstereospecific incorporation of propylene prevents crystallization. However, glass transition temperature is relatively high, near 0°C, so the elastomer has mediocre low-temperature flexibility. The low fluorine content (about 55%) leads to poor resistance to hydrocarbons, especially aromatic solvents. Since the hydrogen-bearing carbon atoms are adjacent to only one fluorine-bearing carbon (rather than two as in VDF-containing polymers), TFE/P copolymers are nonpolar. Thus the elastomer is highly resistant to polar solvents and to dehydrofluorination by base or amines. With its good electrical resistivity, the nonpolar dipolymer has found considerable application in wire and cable insulation. Asahi Glass developed a thermal treatment process to obtain enough active sites for curing with peroxide and radical trap crosslinking systems.[10] Processing characteristics of TFE/P compounds are inferior to those of VDFcontaining fluoroelastomers, so the elastomer is used only in situations where resistance to base or polar fluids is required. Incorporation of small amounts of potential cure-site monomers (e.g., monomers containing bromine or iodine) in TFE/P elastomers has not led to practical cures. Various terpolymers of TFE and propylene with 10%–40% VDF have been developed to get better processing and curing characteristics, as well as high fluorine content for better hydrocarbon resistance. Terpolymers with TFE/P mole ratio about 1.5 contain about 59% fluorine and are curable with bisphenol if VDF content is above 10%.[11] Such terpolymers are more polar in nature, so base resistance is significantly reduced compared to the dipolymer. However, resistance to automotive lubricants containing amine moieties at high temperature is greater than that of VDF/HFP/TFE fluoroelastomers. TFE/P/VDF terpolymers containing 30% or more VDF have better low-temperature flexibility (Tg about –15°C) than dipolymers.

20

FLUOROELASTOMERS HANDBOOK

Recently, copolymers of TFE and propylene with relatively low levels (3%–5%) of trifluoropropylene, CH2=CH–CF3, have been developed.[12] These can be cured with bisphenol systems, and have fluid and base resistance similar to that of TFE/P dipolymer.

2.6

E/TFE/PMVE Elastomers

To get better resistance to polar fluids and bases than that of VDF/HFP/TFE and VDF/PMVE/TFE elastomers, and better low-temperature flexibility and resistance to hydrocarbons than that of TFE/P polymers, elastomeric copolymers (ETP) of ethylene with TFE and PMVE were developed.[13] The useful elastomeric range for this monomer combination is approximately 10–40 mole % ethylene units, 20–40 mole % PMVE units, and 32–60 mole % TFE units. Higher ethylene or lower PMVE contents lead to increased Tg and crystallinity. Glass transition temperatures are higher, about –5°C to –15°C, for the range of E/TFE/PMVE compositions noted than for VDF/TFE/PMVE elastomers of similar fluorine content. Because of the strong alternating tendency of olefins with perfluorinated monomers in free radical polymerization, ethylene is incorporated as isolated units flanked by TFE or PMVE units. Typical monomer sequences are shown in Fig. 2.7 for ETP and GFLT, a VDF/TFE/PMVE elastomer. The polymers have 67% fluorine content and es-

sentially the same elemental content. The change from sequences of contiguous VDF units to E-TFE dyads leads to higher Tg by about 10°C, and to much enhanced resistance to polar solvents and to chemical attack by base or amines. Various cure-site monomers have been studied for ETP curing. Commercial products are based on bromine cure sites that allow conventional peroxide curing with crosslinking agents such as triallyl isocyanurate or trimethallyl isocyanurate. Mechanical properties and thermal stability of such ETP vulcanizates are similar to those of similarly cured VDF-containing fluoroelastomers. Vulcanizate properties and environmental resistance of ETP are compared with other fluoroelastomers in Table 2.3, in tests chosen to show the different characteristics of the elastomers. ETP is compared with a bisphenolcured VDF/HFP dipolymer (A), a peroxide-cured high-fluorine VDF/HFP/TFE polymer (GF), and a peroxide-cured TFE/P dipolymer. Compared to VDF-containing elastomers, ETP has resistance to aliphatic and aromatic fluids similar to that of GF, but greatly superior resistance to polar fluids (e.g., ketones), base, and oil additives. Compared to TFE/ P, ETP has better low-temperature flexibility, similar resistance to base and amine-containing fluids, better resistance to aliphatic and aromatic fluids, and somewhat better resistance to polar fluids. All these fluoroelastomers swell more in fluids than perfluoroelastomers.

ETP: E/TFE/PMVE, 67% F –CF2–CF–CF2–CF2–CH2–CH2–CF2–CF2– | O–CF3 GFLT: VDF/TFE/PMVE, 67% F –CF2–CF–CH2–CF2–CH2–CF2–CF2–CF2– | O–CF3 Figure 2.7 Typical monomer sequences of ETP and GFLT.

2 FLUOROELASTOMER COMPOSITION AND PROPERTIES

21

Table 2.3 Properties of ETP vs Other Fluoroelastomers[14]

A VDF/HFP 66 2 Bisphenol

Polymer GF TFE-P VDF/HFP/TFE TFE/P 70 55 1 4 Peroxide Peroxide

Monomers %F %H Cure Original properties M-100, MPa 1.0 1.2 a T-B, MPa 16.3 19.8 b E-B, % 190 215 Hardness, Shore A 77 79 TR-10, ºC -17 -7 Brittle Point, ºC -20 -48 Heat Aged 70 h at 250ºC T-Ba change, % -4 4 b E-B change, % -3 0 Hardness change, points 1 1 Aged 168 h at 150ºC in EP Gear Lube T-Ba change, % -36 -53 b E-B change, % -58 -56 Hardness change, points 7 2 Volume increase, % 1 3 Aged 168 h at 40ºC in toluene T-Ba change, % -41 -27 b E-B change, % -21 -2 Hardness change, points -10 -10 Volume increase, % 23 11 Aged 168 h at 23ºC in methyl ethyl ketone T-Ba change, % -92 -86 b E-B change, % -79 -77 Hardness change, points -42 -38 Volume increase, % 222 183 Aged 168 h at 100ºC in 30% potassium hydroxide T-Ba change, % -94 -93 b E-B change, % 58 -44 Hardness change, points -47 -49 Volume increase, % 132* 12*

*Samples breaking up. a

T-B = Tensile strength-at-break. b E-B = Elongation-at-break.

ETP E/TFE/PMVE 67 1 Peroxide

0.7 17.1 255 73 2 -58

1.4 15.4 205 82 -11 -34

-16 10 -1

0 17 0

-8 10 -5 6

-6 15 -1 3

-66 -43 -35 64

-21 7 -8 9

-66 -47 -34 77

-34 5 -17 19

12 10 -1 1

-8 29 -3 6

22

FLUOROELASTOMERS HANDBOOK

REFERENCES 1. Ferguson, R. C., J. Amer. Chem. Soc., 86:2003 (1964) 2. Schmiegel, W. W., Die Angewandte Makromolekulare Chemie, 76/77:39–65 (1979) 3. England, D. C., Uschold, R. E., Starkweather, H., and Pariser, R., “Fluoropolymers: Perspectives of Research,” Proc. The Robert A. Welch Conferences on Chemical Research XXVI: Synthetic Polymers, Houston, Texas (1982) 4. Ebnesajjad, S., Fluoroplastics – Volume 1: Non-Melt Processible Fluoroplastics (2000), and Volume 2: Melt Processible Fluoroplastics (2002), Plastics Design Library, William Andrew Inc., Norwich, N.Y. 5. Bowers, S., and Thomas, E. W., “Improved Processing Low Temperature Fluorohydrocarbon Elastomers,” ACS Rubber Division meeting (Oct 17–20, 2000) 6. Stevens, R. D., Thomas, E. W., Brown, J. H., and Revolta, W. N. K., “Low Temperature Sealing Capabilities of Fluoroelastomers,” SAE International Congress and Exposition, Detroit, Michigan (Feb 26 – March 2, 1990) 7. Logothetis, A. L., “Fluoroelastomers,” in; Organofluorine Chemistry: Principles and Commercial Applications, p. 389, (R. E. Banks, et al., eds.), Plenum Press, New York (1994) 8. Breazeale, A. F., U.S. Patent 4,281,092, assigned to DuPont Co. (Jul 28, 1981) 9. Amano, T., and Tatemoto, M., U.S. Patent 4,487,903 (1984) 10. Morozumi, M., Kojima, G., and Abe, T., U.S. Patent 4,148,982, assigned to Asahi Glass Co. Ltd. (Apr 10, 1979) 11. Grootaert, W. M. A., and Kolb, R. E., U.S. Patent 4,882,390, assigned to Minnesota Mining and Manufacturing Co. (Nov 21, 1989) 12. Bauerle, J. G., and Schmiegel, W. W., U.S. Patent Application Publication No. U.S. 2003/0065132 (Apr 3, 2003) 13. Moore, A. L., U.S. Patent 4,694,045, assigned to DuPont Co. (Sep 15, 1987) 14. Stevens, R. D., and Moore, A. L., “A New, Unique Viton® Fluoroelastomer With Expanded Fluids Resistance,” ACS Rubber Division, Cleveland, Ohio (Oct 21-24, 1997)

Part II Fluoroelastomers Technology

3 Fluoroelastomer Monomers 3.1

Introduction

range of monomer mixtures is a major consideration for fluoroelastomers producers.

The major fluorinated monomers for fluoroelastomers are the same as those used for fluoroplastics. Production volumes of fluoroplastics, and thus of their monomers, are much higher than the volumes of fluoroelastomers. This allows the supply of modest amounts of monomers for fluoroelastomers at reasonable cost. Most producers of fluoroelastomers are also producers of fluoroplastics, or allied with these suppliers. Vinylidene fluoride (VDF) accounts for about half the volume of monomers used for fluoroelastomers. Tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) are the other main fluorinated monomers in fluoroelastomers. Perfluoro(methyl vinyl ether) (PMVE), used in specialty fluoroelastomers, is not used in fluoroplastics, but can be made in facilities used for manufacturing the perfluoro(alkyl vinyl ethers) (PEVE and PPVE), monomers used in fluoroplastics. A number of curesite monomers and fluorinated chain-transfer agents are also made in low volumes for specialty fluoroelastomers. Safe handling of these monomers and a wide

3.2

Vinylidene Fluoride (VDF)

Vinylidene fluoride is incorporated at levels of 50 to 80 mole % (30 to 65 weight percent) in the major family of copolymers with hexafluoropropylene and tetrafluoroethylene, and at similar levels in the specialty family of copolymers with perfluoro(methyl vinyl ether) and tetrafluoroethylene. In both families, VDF contributes to low glass transition temperatures to allow good elastomeric behavior. Long sequences of VDF units would lead to undesired crystallinity.

3.2.1

VDF Properties

Vinylidene fluoride (VDF), CH2=CF2, is flammable and is a gas at room temperature. Physical properties of vinylidene fluoride are presented in Table 3.1. It is colorless and almost odorless and

Table 3.1 Properties of Vinylidene Fluoride[1]

Property

Value

Molecular weight

64.038

Boiling point, °C

-84

Freezing point, °C

-144

Vapor pressure at 21°C, kPa

3,683

Critical pressure, MPa

4.434

Critical temperature, °C

30.1

Critical density, kg/m3

417

Heat of formation at 25°C, kJ/mole

-345.2

Heat of polymerization at 25°C, kJ/mole

-474.2

Explosive limits, vol % in air

5.8-20.3

Solubility in water, cm3/100 g at 25°C at 10 kPa

6.3

Activation energy of polymerization, Eo, kJ/mole

161

26

FLUOROELASTOMERS HANDBOOK

boils at –84°C. Vinylidene fluoride can form explosive mixtures with air. Polymerization of this gas is highly exothermic and takes place above its critical temperature and pressure. Propagation rates of VDF with itself and other fluorinated monomers are high, facilitating high production rates of VDF-containing fluoroelastomers.

3.2.2

VDF Synthesis

There are numerous ways to prepare vinylidene fluoride (VDF) which is the main monomer for polyvinylidene fluoride homopolymers and copolymers. A number of these methods are based on dehydrohalogenation of halohydrocarbons. Examples include dehydrobromination of 1-bromo-1,1-difluoroethane[2] or dehydrofluorination of 1,1,1-trifluoroethane.[3][4] Two methods, including the popular commercial technique for VDF production, are described here. Conversion of 1,1,1-trifluoroethane[3] begins by passing this gas through a platinum-lined Inconel tube, which is heated to 1,200°C. Contact time is about 0.01 seconds. The exit gases are passed through a sodium fluoride bed to remove the hydrofluoric acid and are then collected in a liquid nitrogen trap. Vinylidene fluoride (boiling point –84°C) is separated by low temperature distillation. Unreacted trifluoroethane is removed at –47.5°C and is recycled. The effect of temperature and contact time is illustrated in Table 3.2, clearly favoring the high temperature process.

Table 3.2 Effects of Contact Time and Temperature on Vinylidene Fluoride Yield from Dehydrofluorination of 1,1,1-Trifluoroethane[3]

Variable

Case 1

Case 2

Temperature, °C

1,200

800

Contact time, s

0.01

4.4

Space velocity, 1/h

9,700

200

Total conversion, mole %

75.4

76

Conversion to vinylidene fluoride, mole %

74

66

Vinylidene fluoride yield, %

98.1

86.5

By-products yield, %

1.9

13.5

CH3–CF3 → CH2=CF2 + HF The commercial method begins with hydrofluorination of acetylene followed by chlorination,[5] by hydrofluorination of trichloroethane,[6] or by hydrofluorination of vinylidene chloride.[7] In each case the final product, 1-chloro-1,1-difluoroethane, is stripped of a molecule of hydrochloric acid to yield VDF. The following one-step reaction scheme is shown for vinylidene chloride as the starting ingredient: CH2=CCl2 + 2HF → CH3–CClF2 + HCl CH3–CClF2 → CH2=CF2 + HCl A mixture of vinylidene chloride (VC2) and hydrofluoric acid is passed through a heated catalyst bed. The catalyst is prepared by heating CrCl3·6H2O under vacuum to 300°C until it changes color from dark green to a solid violet throughout the porous mass. In this operation, crystallization water is removed (35% weight loss). The cooled mass is comminuted and screened into particles of 2–5 mm diameter that are loaded into a cylindrical reactor and heated to the reaction temperature (250°C–350°C). The resulting gases are condensed and vinylidene fluoride (boiling point –84°C) is separated by low temperature distillation. Table 3.3 provides yield information for a few different reaction conditions. It appears that nearly a 100% yield can be achieved in Case 3. In another one-step process,[8] a mixture of vinylidene chloride and hydrofluoric acid is heated to 400°C–700°C in the presence of oxygen and a catalyst. Aluminum fluoride, alone or in combination with a transition metal such as cobalt, chromium, nickel, zinc or their combinations, is the catalyst for the reaction.

3.3

Tetrafluoroethylene (TFE)

Tetrafluoroethylene is incorporated at up to 30 mole % in VDF-containing fluoroelastomers. Partial replacement of VDF with TFE in these copolymers results in higher fluorine content and thus greater fluid resistance. In perfluoroelastomers and in fluoroelastomers containing olefins, TFE is incorporated at higher levels, some 40 to 70 mole %.

3 FLUOROELASTOMER MONOMERS

27

Table 3.3 Effect of Contact Time and Temperature on Vinylidene Fluoride Yield from Hydrofluorination of Vinyl Chloride[7]

Variable

Case 1

Case 2

Case 3

Case 4

Temperature, °C

345

330

290

250

Space velocity, 1/hr

300

155

200

200

Mole ratio VC2:HF

1:4.7

1:2.7

1:5.3

1:4.7

Vinylidene fluoride yield, %

97.0

96.5

99.8

95.0

3.3.1

TFE Properties

Table 3.4 lists the properties of tetrafluoroethylene. It is a colorless, odorless, tasteless, nontoxic gas that boils at –76.3°C and freezes at –142.5°C. Critical temperature and pressure of tetrafluoroethylene are 33.3°C and 3.92 MPa. TFE is stored as a liquid; vapor pressure at –20°C is 1 MPa. Its heat of formation is reported to be –151.9 kcal/mole. Polymerization of tetrafluoroethylene is highly exothermic and generates –41.12 kcal/mole heat. The extent of the exothermic nature of TFE polymerization can be seen when it is compared with the polymerization of vinyl chloride and styrene, which have heats of polymerization of 23–26 and 16.7 kcal/mole, respectively. A complete description of explosive hazards of tetrafluoroethylene can be found in Ref.10. Safe storage of TFE requires its oxygen content to be less than 20 ppm. A great deal of research has been devoted to safe handling of tetrafluoroethylene. [11] Temperature and pressure should be controlled during its storage. Increasing temperature, particularly at high pressures, can initiate deflagration in the absence of air. In the presence of air or oxygen, TFE forms explosive mixtures. Detonation of a mixture of tetrafluoroethylene and oxygen can increase the maximum pressure to 100 times the initial pressure.[12] Tetrafluoroethylene undergoes free radical addition reactions typical of other olefins. It readily adds Br2, Cl2, and I2, halogen halides IBr and ICl, and nitrosyl halides such as NOCl and NOBr.[13][14] Addition reactions of chlorofluoromethanes and chloromethanes in presence of catalysts like aluminum chloride have been reported.[15] A variety of

other compounds such as alcohols, primary amines, and ammonia can be reacted with tetrafluoroethylene to prepare tetrafluoroethers (HCF2CF 2OR), difluoroacetamides (HCF2CONHR), and substituted triazines.[16] Oxygen can be added to TFE to produce polymeric peroxide[17] or tetrafluoroethylene epoxide.[18] In the absence of hydrogen, sodium salts of alcohols will react with TFE to yield trifluorovinylethers (ROCF=CF2) which can be homo- and copolymerized.

3.3.2

TFE Synthesis

It is difficult to establish exactly the first successful synthesis of tetrafluoroethylene. Publications in the 1890s report a variety of attempts to synthesize TFE by direct reaction of fluorine with carbon, fluorine with chloromethanes, and tetrachloroethylene with silver fluoride.[19]–[22] The data presented are insufficient to determine that these efforts actually lead to TFE. Humiston[23] reported the first documented preparation of TFE in 1919 which has been disputed because of erroneous property data. The first reliable and complete description of synthesis was published in 1933 by Ruff and Bretschneider,[24] who prepared TFE from decomposition of tetrafluoromethane in an electric arc. Separation of TFE from the pyrolysis products was accomplished by bromination followed by dehalogenation with zinc. Numerous other papers have reported synthesis of tetrafluoroethylene. The works that report commercially significant techniques for TFE preparation list fluorspar (CaF2 ), hydrofluoric acid, and chloroform as the starting ingredients.[25]–[32] The reaction scheme is shown below:

28

FLUOROELASTOMERS HANDBOOK

Table 3.4 Properties of Tetrafluoroethylene[9]

Property

Value

Molecular weight

100.02

Boiling point at 101.3 kPa, °C

- 76.3

Freezing point, °C

- 142.5

Liquid density vs. temperature (°C), g/mL - 100 < t <-40 - 40 < t < 8 8 < t < 30

1.202 – 0.0041t 1.1507 – 0.0069t – 0.000037t2 1.1325 – 0.0029t – 0.00025t2

Vapor pressure at T K, kPa 196.85 < T < 273.15 273.15 < T < 306.45

log10PkPa =6.4593-875.14/T log10PkPa =6.4289-866.84/T

Critical temperature, °C

33.3

Critical pressure, MPa

3.92

Critical density, g/mL

0.58

Dielectric constant at 28°C at 101.3 kPa at 858 kPa

1.0017 1.015 15.5

Thermal conductivity at 30°C, mW/(m·K) Heat of formation for ideal gas at 25°C, ∆H,kJ/mole

- 635.5

Heat of polymerization to solid polymer at 25°C, ∆H, kJ/mole

- 172.0

Flammability limits in air at 101.3 kPa,vol%

14-43

1. HF preparation: CaF2 + H2SO4 → 2 HF + CaSO4 2. Chloroform preparation: CH4 + 3 Cl2 → CHCl3 + 3 HCl 3. Chlorodifluoromethane preparation: CHCl3 + 2 HF → CHClF2 + 2 HCl (SbF3 catalyst) 4. TFE synthesis: 2 CHClF2 → CF2=CF2 + 2 HCl (pyrolysis) A few other side compounds are also produced during pyrolysis including hexafluoropropylene, perfluorocyclobutane and octafluoroisobutylene, 1chloro-1,1,2,2-tetrafluoroethane, 2-chloro-1,1,1,2,3,3hexafluoropropane, and a small amount of highly toxic perfluoroisobutylene.

Sherratt[10] has provided a detailed description of preparation of TFE. The overall yield of TFE production depends on the pyrolysis reaction. It proceeds to yield better than 90% TFE at short contact times, low conversions, and subatmospheric pressure in the temperature range of 590°C–900°C. Similar results, comparable to subatmospheric pyrolysis, can be achieved if superheated steam is present during the pyrolysis. Tetrafluoroethylene yields approaching 95% can be achieved at 80% chlorodifluoromethane conversion if the molar ratio of steam to CHClF2 is in the range of 7:1 to 10:1. The products of pyrolysis are cooled, scrubbed with a dilute basic solution to remove HCl, and dried. The resulting gas is compressed and distilled to recover the unreacted CHClF2 and to recover high purity TFE.[10] Tetrafluoroethylene can polymerize

3 FLUOROELASTOMER MONOMERS violently if it is not inhibited. Because of its high heat of polymerization, polymer particles may reach temperatures high enough to provide ignition sources for TFE deflagration. Effective TFE polymerization inhibitors include a variety of terpenes, such as αpinene, Terpene B, and d-limonene.[33] Terpenes were originally thought to act as scavengers of oxygen, a polymerization initiator. However, trace amounts of oxygen can exist in TFE with terpenes present. It appears more likely that terpenes undergo transfer reactions with growing polytetrafluoroethylene free radicals, to form resonance-stabilized radicals that do not undergo further propagation. Tetrafluoroethylene is highly flammable and can undergo explosive deflagration in the absence of air: C2F4 → C + CF4 Heat of reaction values of 57–62 kcal/mole (at 25°C and 1 atm) have been reported for TFE deflagration.[34] Similar amounts of heat are released by the explosion of black gunpowder.[10] To eliminate transportation concerns, TFE preparation and polymerization are usually carried out at the same site.

3.4

Hexafluoropropylene (HFP)

Hexafluoropropylene is incorporated at 15 to 25 mole % in copolymers with VDF and TFE to interrupt monomer sequences that would otherwise crystallize. Thus, although HFP tends to raise the glass transition temperature significantly, this monomer allows the formation of amorphous elastomers.

3.4.1

HFP Properties

Table 3.5 lists the properties of hexafluoropropylene. It is a colorless, odorless, tasteless, and relatively low toxicity gas, which boils at –29.4°C and freezes at –156.2°C. In a four-hour exposure, a concentration of 3,000 ppm corresponded to LC50 in rats.[35] Critical temperature and pressure of hexafluoropropylene are 85°C and 3.254 MPa. Unlike tetrafluoroethylene, HFP is extremely stable with respect to autopolymerization and may be stored in liquid state without the addition of telogen. Hexafluoropropylene is thermally stable up to 400°C–500°C. At about 600°C under vacuum, HFP decomposes and produces octafluoro-2-butene

29 (CF3CF=CFCF3) and octafluoroisobutylene.[18] Under γ-radiation, it reacts with oxygen and produces a 1:1 mole ratio of carbonyl fluoride (COF2) and trifluoroacetyl fluoride (CF3COF).[36] Heat of combustion of hexafluoropropylene is 879 kJ/mole.[34] Under basic conditions, hydrogen peroxide reacts with HFP to form hexafluoropropylene epoxide, which is an intermediate in the preparation of perfluoroalkyl vinyl ethers.[37][38] Hexafluoropropylene readily reacts with hydrogen, chlorine, bromine, but not iodine, by an addition reaction similar to other olefins.[11][39]–[41] Similarly HF, HCl, and HBR, but not HI, add to HFP. By reacting hexafluoropropylene with alcohols, mercaptans, and ammonia, hexafluoro ethers (CF 3CFHCF 2OR), hexafluoro sulfides (CF3CFHCF 2SR) and tetrafluoropropionitrile (CF3CFHCN) are obtained. DielsAlder adducts have been identified from the reaction of anthracene, butadiene, and cyclopentadiene with HFP.[42] Cyclic dimers of HFP can be prepared at 250°C–400°C under autogenous pressure.[16][17] Linear dimers and trimers of hexafluoropropylene can be produced catalytically in the presence of alkali metal halides in dimethylacetamide.[13][15]

3.4.2

HFP Synthesis

Hexafluoropropylene (CF3CF=CF2) was first prepared by Benning, et al.,[48a] by pyrolyzing polytetrafluoroethylene. They identified this compound as hexafluorocyclopropane, erroneously. The full synthesis and identification of HFP was conducted by Henne.[48b] A six-step reaction scheme beginning with the fluorination of 1,2,3-trichloropropane (ClCH2CHClCH2Cl) led to 1,2-dichlorohexafluoropropane (ClCF2CFClCF3). The latter was dehalogenated with zinc in boiling ethanol to yield hexafluoropropylene. There are number of ways to prepare HFP. Excellent hexafluoropropylene yields from the thermal degradation of heptafluorobutyrate (CF3CF2CF2COONa) have been reported.[43] Cracking of tetrafluoroethylene in a stainless steel tube at 700°C–800°C under vacuum is an efficient route for the production of HFP. TFE conversions up to 72% and HFP yields of 82% have been reported.[44][45] Octafluorocyclobutane (TFE dimer), octafluoroisobutylene, and some polymers are the major side products of cracking. The presence of a small amount (3%–10%) of chlorodifluoromethane

30

FLUOROELASTOMERS HANDBOOK

Table 3.5 Properties of Hexafluoropropylene[64]

Property

Value

Molecular weight

150.021

Boiling point at 101.3 kPa, °C

– 29.4

Freezing point, °C

– 156.2

Liquid density vs. temperature (°C), g/mL – 100 < t < – 40 – 40 < t < 8 8 < t < 30

1.202 – 0.0041t 1.1507 – 0.0069t – 0.000037t2 1.1325 – 0.0029t – 0.00025t2

Vapor pressure at T K, kPa 196.85< T < 273.15

log10PkPa = 6.6938 – 1139.156/T

Critical temperature, °C

85

Critical pressure, MPa

3.254

Critical density, g/mL

0.60

Liquid density, g/mL 60°C 20°C 0°C – 20°C

1.105 1.332 1.419 1.498

Heat of formation for ideal gas at 25°C, ∆H, kJ/mole

– 1078.6

Heat of combustion, kJ/mole

879

Toxicity, LC50(rat), 4ha, ppm

3,000

Flammability limits in air at 101.3 kPa, vol% a

Nonflammable for all mixtures of air and HFP

Exposure resulting in fatality of 50% of rats in four hours.

stops the formation of polymer.[46] Thermal decomposition of polytetrafluoroethylene under 20 torr vacuum at 860°C yields 58% hexafluoropropylene.[47] HF reaction with 3-chloro-pentafluoro-1-propene (CF2=CF–CF2Cl) at 200°C, catalyzed by activated carbon, yields HFP.[47] Hexafluoropropylene can be prepared from the catalytic degradation of fluoroform (CHF3) at 800°C–1000°C in a platinum-lined nickel reactor.[10] Another method is copyrolysis of fluoroform and chlorotrifluoroethylene (CF2=CFCl),[33] or chlorodifluoromethane and 1-chloro-1,2,2,2-tetrafluoroethane (CHClFCF3),[47] giving good yields of HFP. More recently, other methods have been reported for the synthesis of hexafluoropropylene. One

technique involves the pyrolysis of a mixture of tetrafluoroethylene and carbon dioxide at atmospheric pressure at 700°C–900°C.[49] Conversions of 20%–80% and HFP yields of better than 80% were obtained. The unreacted tetrafluoroethylene and carbon dioxide were distilled from the product and recycled. HFP can be synthesized from hexachloropropylene via a multi-step process beginning with fluorination.[50] Later steps convert the initial products to CF 3 – CFCl – CF 3 that is dehalogenated to HFP. Other techniques report on the synthesis of hexafluoropropylene from the mixture of a variety of linear and cyclic three-carbon hydrocarbons with a partially halogenated three-carbon acyclic hydrocarbon.[50]

3 FLUOROELASTOMER MONOMERS

3.5

Perfluoro(methyl vinyl ether) (PMVE)

Perfluoro(methyl vinyl ether) (PMVE), CF2=CF–CF3, is used in VDF/TFE/PMVE elastomers at levels of 17 to 23 mole % to obtain specialty fluoroelastomers with low glass transition temperatures. In perfluoroelastomers, copolymers with TFE, PMVE is incorporated at 25 to 40 mole %. About 25 mole % PMVE is incorporated in ethylene/TFE/PMVE elastomers to get amorphous polymers with reasonable low-temperature characteristics. Other perfluoroelastomers are made with higher molecular weight perfluoro(alkoxyalkyl vinyl ethers). PMVE can be made in facilities that synthesize similar monomers used in fluoroplastic copolymers with TFE, perfluoro(ethyl vinyl ether) and perfluoro(propyl vinyl ether).

3.5.1

PMVE Properties

Properties of PMVE are shown in Table 3.6.

3.5.2

PMVE Synthesis

Perfluoro(alkyl vinyl ether) is synthesized by DuPont according to the following steps. 1. Hexafluoropropylene is converted to hexafluoropropylene epoxide (HFPO) by reacting HFP with oxygen under pressure in the presence of an inert diluent at 50°C–250°C or with an oxidizer such as hydrogen peroxide in a basic solution:[52][53]

31 (Basic Solution) CF3CF=CF2 + H2O2 → CF2–CF–CF2 + H2O

\

Molecular weight Boiling point at 101.3 kPa, °C Vapor pressure at 25°C, kPa

/

HFPO 2. HFPO is reacted with a perfluorinated acyl fluoride to produce perfluoro-2-alkoxy-propionyl fluoride: CF2–CF–CF2 + Rf–C=O → RfCF2OCF–C=O | | \ / \ O F CF3 F Perfluoro-2-alkoxy-propionyl fluoride 3. Perfluoro-2-alkoxy-propionyl fluoride is reacted with the oxygen-containing salt of an alkali or alkaline earth metal at an elevated temperature that depends on the type of salt. Examples of the salts include sodium carbonate, lithium carbonate, and sodium tetraborate:[54] RfCF2OCF–C=O + Na2CO3 | \ CF3 F → RfCF2OCF=CF2 + 2 CO2 + 2 NaF For synthesis of PMVE, carbonyl fluoride, F2C=O, is reacted with HFPO in Step 2. Carbonyl fluoride can be made by oxidation of TFE with oxygen; it is also available as a by-product from HFPO production. There are also electrochemical processes for the production of perfluoro-2-alkoxy-propionyl fluoride.[55] An alternative synthesis of PMVE is carried out by Ausimont,[56] using different starting materials: CO + 2F2 → CF3OF CF3OF + ClFC=CClF → CF3–O–CFCl–CF2Cl CF3–O–CFCl–CF2Cl + Zn → CF3–O–CF=CF2

Table 3.6 Properties of Perfluoro(methyl vinyl ether)[51]

Property

O

Value 166 – 21.8 590

Critical temperature, ºC

96.15

Critical pressure, MPa

3.41

Toxicity, average lethal concentration (ALC), ppm

10,000

Flammability limits in air, vol.%

7.5 – 50

32

3.6

FLUOROELASTOMERS HANDBOOK

Olefins: Ethylene and Propylene

Olefin monomers ethylene and propylene are used in base-resistant fluoroelastomers. Ethylene is polymerized with TFE and PMVE at a level of 20– 35 mole % to make a base-resistant fluoroelastomer with good low-temperature characteristics. Propylene is incorporated at 30–50 mole % in TFE/P copolymers or TFE/P/VDF terpolymers. Both olefins exhibit a strong alternating tendency in polymerization with perfluorinated monomers. Conversion of olefin monomers is usually very high, but they tend to slow down polymerization since radicals ending in olefin units are relatively unreactive toward propagation. Ethylene and propylene are readily available from petrochemical suppliers. High purity is necessary, especially for semibatch polymerization, since minor impurities such as ethane or propane undergo transfer reactions that may reduce polymer molecular weight significantly. Properties of ethylene and propylene are listed in Table 3.7. Flammability is a major consideration in the handling of ethylene and propylene. However, gaseous mixtures with TFE have high explosive potential. If an equimolar mixture of TFE and propylene is ignited at an initial pressure above about 2 MPa, the rate of pressure rise may be so high that relief devices are ineffective.

In these polymers, specific monomer sequences present in small amounts provide active sites for cross linking. Other cure systems, such as peroxide-initiated free radical systems, require incorporation of more reactive sites. Cure sites must be incorporated in many specialty fluoroelastomers with main chain compositions resistant to chemical attack. For good cross link density, it is generally desirable to incorporate regularly spaced cure-site monomers at about 1 mole % of total monomer units. This allows formation of cross links at intervals of about 100 monomer units. Since most fluoroelastomers have an average degree of polymerization of some 500 to 2000 monomer units, each chain is tied into a network at multiple points.

3.7.1

Vinyl monomers containing bromine or iodine moieties are often used in peroxide-curable fluoroelastomers. Recently, certain fluorinated vinyl monomers have been incorporated in specialty fluoroelastomers to allow bisphenol curing. Fluorinated vinyl ethers with functional groups in side chains are used in perfluoroelastomers to get highly stable cross links. Many of these monomers require specialized synthesis methods that will not be described here.

3.7.2

3.7

Cure-site Monomers

The major family of VDF/HFP and VDF/HFP/ TFE fluoroelastomers can be cured readily with bisphenols without incorporation of special cure sites.

Types of Cure-site Monomers

Halogenated Vinyl Monomers

Free radical curing of fluoroelastomers is usually effected through reactive bromine- or iodinecontaining sites incorporated at regular intervals along polymer chains or at chain ends. Apotheker and Krusic[58] list a number of bromine-containing olefins for use in several families of peroxide-curable

Table 3.7 Properties of Ethylene and Propylene[57]

Property

Monomer Ethylene

Propylene

Molecular weight

28.05

42.08

Freezing point, ºC

-169

-185

Boiling point at 101.3 kPa, ºC

-104

-47

Liquid density at boiling point, g/mL

0.57

0.61

Critical temperature, ºC

9.6

91.4

Critical pressure, MPa

5.14

4.60

3 FLUOROELASTOMER MONOMERS fluoroelastomers. Their patent examples include the cure-site monomers: BTFB, 4-bromo-3,3,4,4-tetrafluorobutene-1, CH2=CH– CF2– CF2Br; BTFE, bromotrifluoroethylene, CF2=CFBr; 1-bromo-2,2difluoroethylene, CF 2 =CHBr; vinyl bromide, CH2=CHBr; perfluoroallyl bromide, CF2=CF– CF2Br; 3,3-difluoroallyl bromide, CH2=CH–CF2Br; and 4-bromo-perfluorobutene-1, CF2=CF–CF2– CF2Br. Of these monomers, BTFB appears most often in other DuPont patent examples. BTFB is incorporated at very high conversion, and the transfer activity of the incorporated bromine can be controlled by adjustment of polymerization conditions to avoid excessive branching. Most of the other monomers tend to be incorporated at lower conversion, or have more reactive bromine moieties that tend to give excessive branching and gel formation during polymerization. The corresponding iodine-containing monomers (e.g., ITFB) are not as useful, because the more reactive iodine moieties generally give too much branching under most polymerization conditions. Instead, iodine has usually been incorporated on chain ends by the use of iodine-containing transfer agents. Certain partially fluorinated vinyl monomers have been found useful to facilitate bisphenol curing of specialty fluoroelastomers. VDF/PMVE/TFE elastomers containing 2-HPFP, CF2=CH–CF3, can be cured with carefully formulated bisphenol systems. [59] TFE/P elastomers containing 3,3,3trifluoropropene-1, CH2=CH– CF3, also can be cured with bisphenol.[60]

3.7.3

Functional Vinyl Ethers

Various functional groups have been incorporated in vinyl ethers or fluorinated vinyl ethers for use as cure-site monomers. Iodine- and brominecontaining fluorinated vinyl ethers have been studied, but have found little use in commercial fluoroelastomer products. Functional perfluoro(alkoxy alkyl vinyl ethers) [FVEs] are used in TFE/PMVE perfluoroelastomers developed by DuPont to obtain vulcanizates with exceptional thermal stability. D. B. Pattison[61] claimed perfluoroelastomers containing perfluoro(2-phenoxy propyl vinyl ether), curable with the potassium salt of Bisphenol AF, accelerated with the crown ether dicyclohexyl-18-crown6.[62] FVEs containing cyano moieties have been

33 found to be more versatile cure sites for perfluoroelastomers. A. F. Breazeale [63] claimed perfluoroelastomers containing perfluoro(8-cyano-5methyl-3,6-dioxa-1-octene) for curing with tetraphenyltin as adjuvant. A number of other cyano FVEs have been found useful, and several other cure systems have been developed for perfluoroelastomers containing cyano groups.

3.8

Safety Aspects of Monomer Handling

Safety issues encountered in the handling of monomers used in fluoroelastomers fall mainly into the categories of toxicity, flammability, and explosivity. Some of these issues have been noted in the preceding sections on individual monomers. TFE handling has received much attention from producers, with development of special design considerations and handling procedures.[10] Considerable testing has been done to determine explosion potential of TFE and mixtures containing TFE under a range of conditions. Manufacturing processes for various fluoroelastomers give different potential hazards in monomer handling. Many monomer mixture compositions are used over wide ranges of temperature and pressure. Individual monomers are often shipped and stored in liquid form, then vaporized and mixed with other monomers for feeding to polymerization reactors at elevated pressure. Some practical comments on safe handling of monomers are offered below, but detailed analysis by experts is often necessary to determine proper design and procedures for particular process situations.

3.8.1

Toxicity Considerations

In most cases, the major fluoromonomers used in fluoroelastomers are not highly toxic, as noted in the description of properties in preceding sections. However, minor impurities present in some fluoromonomers may be highly toxic (e.g., perfluoroisobutylene in HFP). This necessitates setting low exposure limits for operating personnel. Monitoring of workspaces may be used to detect low levels of fluorinated monomers. Cure-site monomers containing reactive groups vary considerably in toxicity. Iodine- and bromine-

34

FLUOROELASTOMERS HANDBOOK

containing fluorocarbons should generally be handled by procedures designed to avoid personnel exposure. Sometimes minor differences in molecular structure can lead to large differences in toxicity. Some of these materials are produced in small quantities, and toxicity testing may not be as extensive as that for major monomers. Thus cautious handling procedures should be used.

3.8.2

Flammability

Olefin monomers (ethylene and propylene) are highly flammable. TFE and VDF mixtures with air are flammable over considerable ranges. However, other system design considerations often minimize fire hazards. The necessary design and practices to avoid explosion and operator exposure, and to assure monomer polymerizability usually lead to reduced flammability hazards.

3.8.3

Explosivity

Most mixtures of major monomers with compositions approximating those of commercial fluoroelastomers are subject to deflagration if an ignition source is present under conditions prevailing in parts of the polymerization processes. Producers carry out explosion testing to determine how to avoid deflagrations and how to mitigate the consequences of deflagrations to protect personnel and equipment. A number of defenses against explosion are employed: • Eliminating potential ignition sources • Limiting monomer compositions, pressure, and temperature • Minimizing volumes of hazardous monomer mixtures under pressure • Avoiding formation of more explosive mixtures by partial condensation of mixtures • Minimizing volumes and dead spaces in piping systems • Providing relief devices capable of limiting pressure rises after deflagration • Putting barricades around process equipment containing particularly hazardous monomer mixtures

In process areas and equipment containing explosive or flammable monomer mixtures, potential ignition sources should be eliminated. These include electrical, mechanical, and concentrated heat sources. Equipment should conform to electrical classifications appropriate for the monomers handled. This may include choosing instruments so that the energy in circuits is below that required for ignition of particular monomer mixtures. Equipment such as pumps, compressors, and agitators should be designed to avoid metal-to-metal contact of moving parts. Surface temperatures should be kept below autoignition temperatures of monomers. Polymerization initiators should be excluded from monomer feed systems to avoid premature polymerization in particles and formation of hot spots. Exclusion of air from monomer handling systems is necessary, since trace amounts of oxygen react with TFE and VDF to form peroxides which may decompose and initiate propagation. Minor leaks in monomer handling equipment are potential sources of entry for oxygen. Premature polymerization in monomer feed systems may be suppressed by addition of small amounts of inhibitors such as terpenes. For many monomer mixtures used in major fluoroelastomers (e.g., VDF/HFP/TFE and VDF/ PMVE/TFE), it is possible to limit ranges of composition, pressure, and temperature in monomer handling systems to avoid deflagration entirely, or to provide relief systems adequate to avoid equipment damage or personnel injury if a deflagration occurs. Such designs may also involve limiting the volume of monomer mixtures under pressure, so that adequate relief area can be provided. For TFE-rich mixtures used for several specialty fluoroelastomers, it may be necessary to limit operating pressures to avoid ranges in which rates of pressure rise after onset of deflagration are too high for relief to react effectively. Barricaded facilities are often necessary to protect personnel from the potential hazards of such mixtures. Process safety is discussed in more detail in Ch. 4, “Production of Fluoroelastomers,” covering various fluoroelastomer families made by different processes.

3 FLUOROELASTOMER MONOMERS

35

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FLUOROELASTOMERS HANDBOOK

33. Dietrich, M. A., and Joyce, R. M., U.S. Patent 2,407,405, assigned to DuPont (Sep 10, 1946) 34. Duus, H. C., Thermochemical Studies on Fluorocarbons, Indus. Eng. Chem., 47:1445–1449 (1955) 35. Clayton, J. W., Occupational Medicine, 4:262–273 (1962) 36. Lenzi, M., and Mele, A., Nature, 205(4976):1104–1105 (1965) 37. Harris, J. F., Jr., and McCane, D. I., U.S. Patent 3,180,895, assigned to DuPont (Apr 27, 1965) 38. Fritz, G. G., and Selman, S., U.S. Patent 3,291,843, assigned to DuPont (Dec 13, 1966) 39. Knunyants, I. L., Mysov, E. I., and Krasuskaya, M. P., Izvezt. Akad. Nauk S. S. S. R., Otdel. Khim. Nauk, pp. 906–907 (1958) 40. Haszeldine, R. N., and Steele, B. R., J. Chem. Soc., pp. 1592–1600 (1953) 41. Miller, W. T., Jr., Bergman, E., and Fainberg, A. H., J. Am. Chem. Soc., 79:4159–4164 (1957) 42. McBee, E. T., Hsu, C. G., Pierce, O. R., and Roberts, C. W., J. Am. Chem. Soc., 77:915–917 (1955) 43. Locke, E. G., Brode, W. R., and Henne, A. L., J. Am. Chem. Soc., 56:1726–1728 (1934) 44. Ruff, O., and Willenberg, W., Chem. Ber., 73:724–729 (1940) 45. Hals, L. T., Reid, T. S., and Smith, G. H., J. Am. Chem. Soc., 73:4054 (1951) 46. Hauptschein, M., and Feinberg, A. H., U.S. Patent 3,009,966, assigned to Pennwalt Chemicals Corp. (Nov 21, 1961) 47. Lewis, E. E., and Naylor, M. A., J. Am. Chem. Soc., 69:1968–1970 (1947) 48. (a) Downing, F. B., Benning, A. F., and McHarness, R. C., U.S. Patent 2,384,821, assigned to DuPont (Sep 18, 1945). (b) Henne, A. L., and Wealkes, T. P., J. Am. Chem. Soc., 68: 496 (1946) 49. West, N. E., U.S. Patent 3,873,630, assigned to DuPont (Mar 25, 1975) 50. Webster, J., et al., U.S. Patent 5,068,472, assigned to DuPont (Nov 26, 1991) 51. DuPont Co., PMVE Material Safety Data Sheet (Jan 26, 1999) 52. Carlson, D. P., U.S. Patent 3,536,733, assigned to DuPont (Oct 27, 1970) 53. Eleuterio, H. S., and Meschke, R. W., U.S. Patent 3,358,003 (Dec 12, 1967) 54. Fritz, G. G., and Selman, S., U.S. Patent 3,291,843, assigned to DuPont (Dec 13, 1966) 55. Brice, T. J., and Pearlson, W. H., U.S. Patent 2,713,593, assigned to Minnesota Mining and Manufacturing Co. (Jul 1955) 56. Guastalla, G., Guglielmo, G., Fortunato, G., and Gregorio, G., IT Patent 1,196,519, assigned to Ausimont (Jul 18, 1986) 57. Liley, P. E., in: Chemical Engineers’ Handbook, 4th Ed., Sec. 3 (R. H. Perry, C. H. Chilton, and S. D. Kirkpatrick, eds.), McGraw-Hill Book Co., New York (1963) 58. Apotheker, D., and Krusic, P. J., U.S. Patent 4,035,565, assigned to DuPont (Jul 12, 1977) 59. Bowers, S., and Schmiegel, W. W., US Patent 6,329,469, assigned to DuPont Dow Elastomers LLC (Dec 11, 2001) 60. Bauerle, J. G., and Schmiegel, W. W., US Patent Application Publication No. US (Apr 3, 2003)

2003/0065132

61. Pattison, D. B., U.S. Patent 3,467,638, assigned to DuPont (Sep 16, 1969) 62. Barney, A. L., and Honsberg, W., US Patent 3,580,889, assigned to DuPont (Jul 28,1981) 63. Breazeale, A. F., U.S. Patent 4,281,092, assigned to DuPont (Jul 28, 1981) 64. Gangal, S. V., “Fluorine Compounds, Organic (Polymers),” “Perfluorinated Ethylene-Propylene Copolymers,” in: Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed., 11:644-656, John Wiley & Sons, New York (1994)

4 Production of Fluoroelastomers 4.1

Introduction

This chapter covers various aspects of the production of fluoroelastomer copolymers. After a general description of commercial production processes, free radical copolymerization and emulsion polymerization kinetics are described. Process variations designed to attain desired characteristics of major product families are summarized, with more detail covered in Chs. 5 and 6 on cure systems and processing of the various fluoroelastomer composition families. Other process steps, such as monomer recovery and polymer isolation, are described, along with process safety considerations. Finally, commercial processes are covered in detail.

4.2

General Process Description

Most commercial fluoroelastomers are copolymers of two or more monomers made by free-radical emulsion polymerization. Figure 4.1 is a schematic of the general process. The polymerization operation may be carried out in continuous or semibatch mode. Numerous process variations are used to produce different products. Molecular structures of fluoroelastomers are determined by polymerization and isolation process conditions, so product and process

Figure 4.1 General fluoroelastomer production process.

development are usually carried out simultaneously in laboratory semiworks units designed to emulate commercial operation. As indicated in Fig. 4.1, water and other liquid ingredients are added to the polymerization reactor. These include an initiator and soap as aqueous solutions, and an optional chain-transfer agent and curesite monomer. Two or three major monomers are fed as gases by a compressor. The reactor is maintained at the temperature, pressure, and holdup time required for the particular product. Air and other impurities are carefully excluded from the feed and reactor systems. Polymer is formed in the reactor as a dispersion containing 15%–30% solids, with particle size generally in the range 100–1000 nm diameter. At reactor conditions, much of the monomer present is dissolved in the particles at concentrations of 3%–30%, depending on polymer and monomer compositions, and on prevailing temperature and pressure. The polymer dispersion is discharged from the reactor to a degassing vessel maintained at low pressure to allow removal of residual gaseous monomer. In continuous reactor operation, the reaction vessel is maintained liquid-full and the dispersion is let down through a back-pressure control valve to the degasser. Recovered monomer is recycled continuously to the reactor through the monomer feed compressor. In semibatch reactor operation, the dispersion is let down to the degasser at the end of the

38

FLUOROELASTOMERS HANDBOOK

polymerization, and recovered monomer is held for subsequent recharging of the reactor for succeeding batches of the same composition. Additional vessels may be provided for final monomer removal and dispersion blending prior to isolation. Polymer isolation is effected by chemical coagulation of the dispersion, followed by separation of polymer crumb from the aqueous phase, removal of soluble soap and salt residues, and dewatering and drying of the polymer. Usual coagulants are soluble salts of aluminum, calcium, or magnesium. Various means of separating polymer from the coagulated slurry are used commercially, including continuous centrifuges, filters, and dewatering extruders. Methods used for salt removal include washing by repeated reslurrying in fresh water and separation of polymer; washing on a batch filter or continuous filter belt; or expelling most of the aqueous phase in a dewatering extruder. The purified polymer is dried in a batch oven or continuous conveyor dryer, or in a drying extruder. The isolated fluoroelastomer is generally formed into pellets or sheet for packaging and sale as gum polymer. Alternatively, the polymer may be precompounded by adding curatives and processing aids before forming and packaging.

Chain radical reactivity is assumed independent of radical size, and depends only on the reactivity of the last unit added to the chain. Chain length is long, so monomer consumption is assumed to occur only by propagation. A stationary state is assumed with respect to radical concentrations. That is, the rate of change of radical concentration is negligible compared to the rate of polymerization. The following sections discuss the general free radical reaction scheme, followed by some aspects of relative monomer reactivity important in copolymerization of fluoroelastomers.

4.3.1

General Reaction Scheme

The steps in free radical polymerization are depicted in simple form below, together with individual rate expressions involved. Initiation: Eq. (4.1) I → 2R· R· + M → R1· Propagation: Eq. (4.2) Rn· + M → Rn+1·

Free Radical Copolymerization

Free radical polymerization involves four types of reactions: initiation, propagation, transfer, and termination. Initiation includes generation of free radicals, moieties with free valences which are highly reactive, followed by addition of vinyl monomer units. The double bonds of the monomer open to form growing radical ends. Propagation is a relatively rapid process, with continued addition of monomer units to growing radical chains. Growth of a chain may be stopped by a transfer reaction in which the radical is capped by a reactive atom such as hydrogen or halogen and the radical activity is transferred to the residue of the transfer agent. This radical may add monomer to continue growth of the kinetic chain. Termination occurs by reaction of radicals to form dead chains that do not propagate further. Kinetic analysis is considerably simplified by making a number of assumptions that are good approximations in practical polymerization systems.

kp[M][R·]

Transfer: Eq. (4.3) Rr· + T → Pr + T·

4.3

2f k d[I]

ktr[T][R·]

Termination: Eq. (4.4) Rr· + Rs· → Pr+s

2kt[R·]2

In the scheme above, initiation takes place by thermal decomposition of an initiator I, followed by addition of the first monomer unit at efficiency f. Propagation takes place quickly with addition of many monomer units. The rate coefficient kp is independent of radical chain length, but dependent on the nature of the radical end and the monomer (more detail is contained in the following section (Sec. 4.3.2). Transfer involves the transfer of a reactive atom such as hydrogen or halogen (usually from the transfer agent to cap the radical end) and transfer of the radical activity to the transfer agent residue. The new radical usually adds monomer to continue propagation of the kinetic chain. If the transfer radical has low reactivity toward propagation, it slows down the polymerization, acting as a retarder or inhibitor. Termination by combination of radicals is assumed, valid for most fluorocarbon polymer systems.

4 PRODUCTION OF FLUOROELASTOMERS

39

Kinetics relationships based on the reactions above must take into account the nature of the polymerization system. In suspension polymerization of fluoroelastomers, all the reactions occur in relatively large particles swollen with monomer. Emulsion systems are more complicated; reactions in both the aqueous phase and relatively small monomer-swollen particles must be considered. Initiation and propagation of short radical chains take place in the aqueous phase, along with termination and transfer reactions. A fraction of the short-chain radicals enter particles, where they undergo propagation to high molecular weight and also undergo transfer and termination reactions to form dead polymer chains. Rates in particles (either suspension or emulsion cases) may be reduced by the high-viscosity environment that reduces reactant mobility. Termination rates may be drastically reduced, since diffusion of chain radicals is greatly hindered.

Mayo,[3] Simha,[4] and Wall,[5] by making the further assumption that steady state applies to each radical type separately. This means that the rate of conversion of radical M1· to M2· (Eq. 4.5b) is balanced by the reverse conversion (Eq. 4.5d):

4.3.2

The ratio of monomers incorporated in the polymer is obtained by dividing Eqs. (4.8) by (4.9) and substituting for the ratio of radical types in Eq. (4.7). The resulting copolymer composition relationship is simplified by denoting the ratio of monomers in the polymer rp1/rp2 as Y and the ratio of monomer concentrations [M1]/[M2] as X, and defining the monomer reactivity ratios r1 = k11/k12 and r2 = k22/k21:

Copolymer Composition Relationships

Since fluoroelastomers are copolymers of two or more monomers, an understanding of the relationship between polymer composition and monomer ratios in the polymerization system is necessary for successful control. Composition relationships for dipolymers were derived by early workers in the polymer field. Using the assumption that the rate of monomer addition to a radical chain depends only on the nature of the last unit on the chain, Dostal,[1] in 1936, showed that only four propagation reactions and corresponding rates would describe copolymerization of two monomers: Eq. (4.5a)

M1· + M1 → M1·

k11[M1·][M1]

Eq. (4.5b)

M1· + M2 → M2·

k12[M1·][M2]

Eq. (4.5c)

M2· + M2 → M2·

k22[M2·][M2]

Eq. (4.5d)

M2· + M1 → M1·

k21[M2·][M1]

In 1944, a useful copolymer composition relationship was derived independently by Alfrey,[2]

Eq. (4.6)

k12[M1·][M2] = k21[M2·][M1]

Then the ratio of the radical types is:

Eq. (4.7)

[M1 ·] = k21 [M1 ] [M 2 ·] k12 [M 2 ]

The rates of incorporation of each monomer into polymer are given by: Eq. (4.8)

rp1 = k11[M1·][M1] + k21[M2·][M1]

Eq. (4.9)

rp2 = k12[M1·][M2] + k22[M2·][M2]

Eq. (4.10)

Y=X

(r1 X + 1) (r2 + X )

This copolymer relationship can be applied directly to fluoroelastomers containing two major monomers. Under polymerization conditions used for commercial production, whether continuous or semibatch operation, compositions of polymer and unreacted monomer (thus Y and X ) are held constant by continuous feed of monomer to the reactor. This allows estimation of reactivity ratios from carefully designed experiments. Composition relationships for systems of more than two monomers are much more complex.[6] However, the compositions of terpolymers and tetrapolymers were shown to be functions of the reactivity ratios of the various pairs of monomers in the system. This is helpful in determining characteristics such as monomer sequencing in such polymers.

40

FLUOROELASTOMERS HANDBOOK

4.3.3

Monomer Reactivity Ratios

To facilitate evaluation of reactivity ratios for copolymers with corresponding Y and X ratios determined over a range of compositions, Eq. (4.10) can be rearranged into several forms. Reactivity ratios r1 and r2 can be determined as the slope and intercept of a linear plot of the composition relationship in one of the following forms:

Eq. (4.11)

Eq. (4.13)

X

r1 =

X

X (Y − 1) X2 = (r1 ) − r2 Y Y Each polymerization experiment with reliable values of Y and X gives a point on the line, and regression analysis (least squares) can be applied to obtain the reactivity ratios. Alternatively, Eq. (4.10) can be solved for one of the reactivity ratios to obtain the following relationships: r1 = (r2 )

(Y − 1) Y + 2 X X

r2 = (r1 )

X 2 X (Y − 1) − Y Y

Y = r1X + 1

or

(Y − 1) = r − (r ) Y 1 2 2

or

Eq. (4.12)

simplified further. In VDF/HFP copolymerization, the reactivity ratio r2 for HFP can be taken as zero. To a close approximation, HFP does not add to HFP· radical ends in the presence of VDF. The copolymer relationship for r2 = 0 becomes:

or

Each experiment gives a straight line in a plot of r1 versus r2. The reactivity ratios can then be estimated from the intersections of a number of lines from individual experiments. The extent of the region covered by intersections gives a visual idea of the errors in the reactivity ratio estimates. For important dipolymer fluoroelastomer families, the copolymer composition in Eq. (4.10) can be

(Y − 1) X

Little polymerization data over a range of VDF/ HFP compositions have been published to allow good estimates of reactivity ratios. Some patent examples provide useful information, such as Example 1 of Moore and Tang, U.S. Patent 3,929,934.[7] In this example, the first of two reactors in series was operated in continuous mode to make VDF/HFP copolymer at high conversion (93%). At this conversion and the prevailing conditions of temperature (110°C) and pressure (6.2 MPa), all the unreacted monomer can be assumed to be dissolved in the polymer particles. In this continuous emulsion polymerization, a 2-liter reactor was fed with 8.0 L/h water (nominal residence time 0.25 hour) containing 16 g/h ammonium persulfate initiator and 3.0 g/h NaOH for pH control. The effluent polymer dispersion contained about 19% solids; the polymer composition was about 58% VDF and 42% HFP. A mass balance on monomer allows calculation of the ratios Y and X as shown in Table 4.1. From unreacted monomer composition, X = 0.36, and from the corresponding polymer composition, Y = 3.3, so that r1 = 6 from Eq. (4.13). This is a reasonable value, but should be considered as only a rough estimate (say, within ± 50%). From composition ranges noted in patents, perfluoroelastomers with major monomers TFE and PMVE must contain about 33 mole % PMVE to be

Table 4.1 Mass Balance on VDF/HFP Monomer

Monomer: VDF (1)

Feed g/h 1100

Monomer: HFP (2)

900

130

0.87

770

5.13

2000

150

1.18

1850

22.01

Monomer

Total:

Unreacted g/h mol/h 20 0.31

g/h 1080

Polymer mol/h 16.88

wt % 58 42

4 PRODUCTION OF FLUOROELASTOMERS

41

well in the amorphous composition range with negligible crystallinity from long runs of TFE units. This is in contrast to the VDF/HFP system, where only about 20 mole % HFP is sufficient to avoid crystallinity. Thus, it appears that there is significant clumping of adjacent PMVE units, allowing formation of relatively long runs of TFE units in TFE/PMVE copolymers. Then the propagation rate coefficients k11 and k22 and the reactivity ratios r1 and r2 for TFE and PMVE, respectively, must be greater than zero. Published data on TFE/PMVE polymerization are insufficient for calculation of reactivity ratios. However, in a subsequent section on monomer sequencing, it will be shown that a reactivity ratio product r1r2 ~ 0.5 is reasonable for this system. Substitution of r1/0.5 for r2 in the copolymer composition Eq. (4.10) yields a quadratic equation that can be solved for the reactivity ratio r1:

Eq. (4.14)

(

Y −1+ 1 + Y 2 r1 = 2X

)

½

Example 1 of Apotheker and Krusic, U.S. Patent 4,035,565,[8] provides polymerization data on a terpolymer of TFE and PMVE with a small amount of cure-site monomer bromotrifluoroethylene (BTFE). Continuous emulsion polymerization was carried out in a liquid-full 3.8-liter reactor at 70°C and 4.1 MPa with about 2.7 hours residence time based on latex flow. Redox initiator components ammonium persulfate (6.38 g/h) and sodium sulfite (5.25 g/h), buffer dibasic sodium phosphate heptahydrate (4.5 g/h), and soap ammonium perfluorooctanoate (12.0 g/h) were fed in 1.2 L/h total water. A mass balance on monomer was obtained at steady state; the results are shown in Table 4.2. Ignoring BTFE in the calculation of the TFE/ PMVE monomer ratios, X = 0.20 and Y = 2.24. From

Eq. (4.14), reactivity ratios are approximately r1 ~ 9 and r2 ~ 0.06 under the assumption r1r2 ~ 0.5. For TFE/propylene copolymerization, both reactivity ratios are near zero, so the copolymer composition relationship reduces to Y = 1 at all values of X. Thus TFE and propylene units would alternate, no matter what the monomer ratio in the reactor. This assumption is not quite correct, since typical commercial TFE/P elastomers contain some 52–54 mole % TFE. It appears that with TFE in great excess, say X > 10, Y is ~ 1.1, indicating r1 ~ 0.01 for TFE. The monomer pair VDF and TFE appears to approximate the case r1r2 = 1. Substitution of 1/r1 for r2 in the copolymer composition equation (Eq. 4.10) leads to Y = r1 X, indicating that the monomer ratio in the polymer is directly proportional to the ratio of unreacted monomer, so-called random copolymerization. VDF/TFE copolymers are crystalline plastics with melting points varying with composition. Terpolymers with relatively high TFE content (45%–65%) and low HFP content (15%–20%) are sold by Dyneon as flexible thermoplastics with melting points 120°C–180°C. In elastomeric terpolymers of VDF and TFE with HFP or PMVE, the reactivity ratios of HFP or PMVE with respect to either VDF or TFE can be considered as near zero. Thus units of HFP or PMVE are usually isolated between mixed sequences of VDF and TFE units.

4.4

Emulsion Polymerization

Essentially all fluorocarbon elastomers are produced commercially by emulsion polymerization, depicted schematically in Fig. 4.2. As previously described, polymerization occurs in monomer-swollen polymer particles some 100 to 1000 nanometers (nm) in diameter, not in a liquid-liquid emulsion as implied by the name. Particles are stabilized by surfactant,

Table 4.2 Mass Balance on TFE/PMVE Monomer with a Small Amount of BTFE Cure-site Monomer

Monomer Monomer: TFE (1)

Feed g/h 260

Unreacted g/h mol/h 14 0.14

g/h 246 183

1.10

41.8

30.4

2.0

1.6

0.71

Polymer mol/h wt % 2.46 56.2

Monomer: PMVE (2)

300

117

Monomer: BTFE

10

1

9

0.06

Total

570

132

438

3.62

mol % 68.0

42

FLUOROELASTOMERS HANDBOOK Eq. (4.15)–O3SO– OSO3– → 2 •OSO3– The rate of decomposition is determined mainly by temperature, but is also somewhat dependent on pH. Fluoroelastomer polymerization is usually carried out at relatively low pH (~ 3–6), and the first order thermal decomposition rate coefficient kd (min-1) is given in the Arrhenius form as[10]

Eq. (4.16) Figure 4.2 Emulsion polymerization.

either added or made in situ by polymerization in the aqueous phase. A water-soluble initiator system generates free radicals, some of which grow and form or enter particles. In most fluoroelastomer polymerization systems, there is no sizeable reservoir of liquid monomer present. Much of the monomer is dissolved in the polymer particles, and is replenished by a continuous feed during the polymerization. Even in semibatch polymerization, the amount of monomer in the reactor vapor space is relatively small. The segregation of growing radicals in small particles under conditions of limited termination by incoming radicals allows attainment of the high molecular weights desired for good elastomeric properties. Especially for VDF-based fluoroelastomers, emulsion systems allow very high productivity in reactors of modest size.

E  k d = A exp a   RT   − 17070  = 5.62 × 1018 exp   T 

In this equation, the factor A is in units min-1, activation energy Ea is in cal/mole, gas constant R = 1.987 cal/mole K, and absolute temperature T is in kelvin. With the high activation energy Ea = –33,900 cal/ mol, the rate of decomposition of persulfate is quite sensitive to temperature (Table 4.3). At temperatures below about 80°C, persulfate decomposition is slow, so relatively high initiator concentrations would be necessary to get reasonable radical generation rates. Instead various redox initiator systems may be used. Sulfite is a typical reducing agent that reacts rapidly with persulfate to generate two types of radicals: Eq. (4.17)

–O

3SO–OSO3

–

+ SO32–

→ SO42– + •SO3– + •OSO3–

4.4.1

Emulsion Polymerization Kinetics

Recent work by R. G. Gilbert[9] and coworkers at Sydney University and DuPont has greatly clarified the various complicated steps involved in emulsion polymerization, allowing development of improved kinetics models and setting of conditions to get polymer structures desired for commercial applications. Polymerization mechanism. In emulsion polymerization, a water-soluble initiator system forms free radicals in the aqueous phase. Typically, thermal decomposition of persulfate is used to generate radicals by symmetrical scission of the O– O bond of the anion:

Table 4.3 Thermal Decomposition of Persulfate[10]

Temperature, °C

103 kd, min-1

Half life, min

50

0.063

11,000 (184 h)

60

0.307

2,260 (38 h)

70

1.37

507 (8.4 h)

80

5.60

124 (2.0 h)

90

21.2

33

100

4.9

9

110

247

3

120

769

1

4 PRODUCTION OF FLUOROELASTOMERS At temperatures below 60°C, a small amount of a catalyst such as a copper salt may be added to increase the redox rate. In continuous polymerization, the components of the redox initiator system are fed to the reactor in separate streams. In semibatch polymerization at low temperature, persulfate is usually charged initially, and the reducing agent is added at a controlled rate to get the desired radical flux, twice the molar addition rate of sulfite times an efficiency factor. A considerable fraction of primary radicals may be lost by recombination with each other before monomer addition occurs to complete the initiation process. For VDF/TFE/HFP or PMVE elastomers, VDF and TFE are the most likely monomers to add to primary initiator radicals. For initiation with sulfate ion radicals, the following reactions would be typical: Eq. (4.18)

CH2=CF2 + •OSO3– → •CF2– CH2– OSO3–

Eq. (4.19)

CF2=CF2 + •OSO3– → •CF2– CF2–OSO3–

Perfluorinated sulfate end groups are likely to hydrolyze to carboxylate ends at polymerization conditions: Eq. (4.20)

•~CF2– CF2– OSO3– + 2 H2O → •~CF2– COO– + H2SO4 + 2 HF

The generation of sulfuric and hydrofluoric acids by hydrolysis reactions usually necessitates addition of a base or buffer to keep the pH above 3. Initiation with •SO3– leads to formation of sulfonate end groups, e.g.: Eq. (4.21)

CF2=CF2 + •SO3– → •CF2– CF2– SO3–

Unlike perfluorinated sulfate end groups, perfluorinated sulfonate ends are resistant to hydrolysis. These small radicals propagate further in the aqueous phase, reacting with the small amount of dissolved monomer present. Because polymer particles are stabilized by adsorbed anionic surfactant

43 and also carry surface charge from ionic end groups of polymer, growing radicals in the aqueous phase must add several monomer units (say, 3 to 5) to become surface active and hydrophobic enough to overcome the electrostatic surface barriers and enter particles. With this delay in entry, small radicals may undergo other reactions (e.g., termination reactions) such as: Eq. (4.22) •CF2– CH2– CF2– CH2– OSO3– + •CF2– CH2– CF2–CH2–CF2–CH2–OSO3– → –O3SO– (CH2– CF2)2– (CF2CH2)3– OSO3– The resulting combination products may serve as effective surfactants to stabilize particles. Depending on initiator level, little or no added surfactant may be necessary for adequate stabilization of dispersions of VDF copolymers. Note that if, instead of VDF or TFE, other less reactive monomer units such as HFP or PMVE add to these short radicals, termination becomes more likely than further propagation. Transfer to an active water-soluble species may result in a nonionic radical (e.g., transfer with isopropyl alcohol): Eq. (4.23) •CF2– CH2– OSO3– + (CH3)2CHOH → HCF2– CH2– OSO3– + (CH3)2C •OH Presumably, such a polar, uncharged radical would need to add only one or two monomer units to become hydrophobic enough to enter a particle. With all these possible aqueous-phase reactions, the fraction of primary radicals generated that grow and enter particles to continue growth to high polymer may be rather low (0.2–0.6), especially at high initiator levels. Once a radical enters a particle, it propagates rapidly by addition of monomer dissolved in the particle at much higher concentration than present in the aqueous phase. In some systems (e.g., TFE/ PMVE), high added soap levels give a large number of small particles (say, 200 nm in diameter) highly swollen with 20%–30% monomer. It is likely that the ideal emulsion 0,1 polymerization case prevails

44 here. That is, each particle contains only one or no growing radical at any time. No more than one radical at a time propagates in such a small particle; entry of a second radical leads to rapid termination, with no radical activity until another radical enters to restart polymerization. At the other extreme are most VDF copolymer systems. Here, very low added soap levels give a small population of large particles (500–1000 nm diameter) with relatively low concentration of dissolved monomer (about 10%). In these highly viscous particles, the mobility of long-chain radicals is so low that termination rates are drastically reduced. Only very small radicals entering from the aqueous phase or formed by transfer reactions are effective in terminating long chains. A large number of growing radicals (10 or more) may coexist in such large particles. Radical lifetimes may be quite high in such systems, so polymerization rates and molecular weights may be high. Typically, transfer agents are used to control molecular weights. Soaps used in the emulsion polymerization of fluoroelastomers are usually fully or partially fluorinated anionic surfactants. Efficacy at low concentrations and high water solubility are desirable to get low residual soap levels in isolated polymer. Soaps should be unreactive to radicals at polymerization conditions, to avoid excessive transfer and attachment of ionic soap moieties to polymer chain ends. Perfluoroalkyl carboxylates or sulfonates with 8- or 9-carbon alkyl chain lengths are inert and effective dispersion stabilizing agents. Ammonium perfluorooctanoate has been preferred for many fluoroelastomer emulsion systems. However, this stable soap is persistent in the environment and is not readily eliminated from the body after exposure. A major supplier (3M Co.) has stopped its production, and its use in fluoropolymer production is being phased out or reduced. A number of partially fluorinated soaps are effective, especially for VDF copolymers. These are usually of the structure F– (CF2– CF2)n–CH2– CH2– X–M+, with n = 2–8 (mostly 3–4); – X– may be sulfate, phosphate, or sulfonate, and M+ is H+, NH4+, or an alkali metal ion. The sulfate and phosphate forms are highly effective,[11] but may participate in unwanted transfer reactions. Recently, a particular partially fluorinated alkyl sulfonate form, F–(CF2– CF2)3– CH2– CH2– SO3–Na+, has been found to be a good replacement for ammonium perfluorooctanoate in many fluoroelastomer emulsion polymerization systems, both semibatch and con-

FLUOROELASTOMERS HANDBOOK tinuous.[12] This soap is effective as a dispersion stabilizer, inert to radical attack by transfer, and readily removed during polymer isolation. Polymerization rate Rp in an emulsion system can be represented as:

Eq. (4.24)

Rp =

k p [M ]N p nr M o NA

In this relationship, kp is the overall propagation rate coefficient in the particles; [M] is the molar monomer concentration in a particle; Np is the total number of particles; nr is the average number of radicals per particle; Mo is the average monomer molecular weight; and NA is Avogadro’s number (6.022 × 1023). Note that kp[M ]Mo may be applied to a copolymer using average values for a particular composition. For most systems of interest, available data are insufficient to evaluate key parameters in the rate expression. The number of particles and the average number of radicals per particle are particularly difficult to determine. Factors that affect the number of particles are considered in the next section on particle nucleation. Particle formation mechanisms. Most studies of emulsion polymerization are based on batch polymerization of a liquid monomer, so particle formation and growth are treated as occurring in three distinct intervals:[13] I. Particle nucleation period: characterized by presence of monomer droplets and soap micelles, with formation of particles that grow in number and size. Polymerization rate Rp increases. II. Particle growth period: monomer droplets are present, but no micelles; particle number is constant, particle size grows. Rp is steady or increases. III. Final stage: monomer is consumed, so Rp decreases with decreasing monomer concentration in particles. This is not an adequate picture of the fluoroelastomer emulsion polymerization processes. These are semibatch or continuous polymerizations in which monomer composition and concentration in particles are kept essentially constant by continuous feed of monomer to the reactor. No large reservoir of reactive monomer is present. Thus, only modified forms of

4 PRODUCTION OF FLUOROELASTOMERS intervals I and II exist in semibatch polymerization, and nucleation and growth stages coexist in continuous polymerization. For most fluoroelastomer systems, polymerization ceases when fresh monomer feed is stopped. The composition of unreacted monomers in the reactor, while necessary to set the copolymer composition, is not usually reactive enough toward propagation to support appreciable polymerization rates. In his analysis of particle formation, Gilbert[14] notes that a short radical formed from initiator with monomer addition must meet one of three fates: aqueous-phase termination, entry into a particle, or forming a new particle. Entry into a particle can occur when a sufficient degree of polymerization (number of monomer units added to an initiator fragment) denoted as z is reached so that the radical becomes surface active. Particle formation can occur when such a z-mer enters a micelle or when the radical grows to a sufficient longer degree of polymerization, jcrit , to homogeneously precipitate and nucleate to a precursor particle. Particle formation ceases when the number and size of particles reach levels such that all z-mer radicals are captured. Thus, two mechanisms of particle formation may occur: homogeneous nucleation in systems with soap levels below the critical micelle concentration (cmc), and micellar entry in systems above the cmc. Both particle formation mechanisms must be considered in fluoroelastomer polymerization systems. For VDF copolymers, the polymerizations are

45 characterized by low surfactant levels and high propagation rates at low monomer concentrations. In these systems, particle formation is by homogeneous nucleation. For most TFE copolymers containing no VDF (e.g., TFE/PMVE, TFE/P), soap levels are very high and propagation rates are low. Micellar entry may prevail as the major mode particle formation in these systems. Particle formation by homogeneous nucleation. Figure 4.3 illustrates steps in particle formation by homogeneous nucleation and coagulation as described by Gilbert.[15] After initiation by addition of a monomer unit to a primary ionic radical, the small radical may propagate in the aqueous phase. With ionic head groups such as sulfate, sulfonate, or carboxylate, these radicals are soluble in water when only a few monomer units (say, 1–3) have been added. Many are lost by mutual termination, becoming dead chains with one or two ionic head groups. Depending on their size, these may serve as surfactants to stabilize particles. When a sufficient number of units, z, have been added, a growing z-mer becomes surface active so that it can overcome the electrostatic surface barrier and enter a particle. A radical that propagates further to a critical length, jcrit , becomes insoluble in water, so it may coil and precipitate to form a precursor particle. Monomers enter such precursor particles, so the radicals may continue to grow. Precursor particles grow both by propagation and by co-

Figure 4.3 Particle formation by homogeneous-coagulative nucleation.[15]

46 agulation with other precursor particles, eventually becoming mature particles. Particles are stabilized by ionic end groups on their surfaces. These are from a combination of added surfactant, oligomeric surfactant formed in situ by aqueous phase termination of short radicals, and polymeric chains anchored in the particles. Ordinarily, the total of such ionic end groups is relatively low, since little or no soap is added and initiator levels may be low. Such dispersions usually have low particle number and large particle size. The first quantitative model of homogeneous nucleation was developed by Fitch and Tsai[16] and augmented by Hansen and Ugelstad[17] as HUFT theory. Coagulation of small particles was taken into account by Richards, Congalidis, and Gilbert,[18] using an extension of the standard DLVO model of colloid science.[19] This describes the coagulation of small particles stabilized by surface charge. Later versions of the model take better account of the variation of the number of particles with ionic strength.[20] Richards and Congalidis have developed proprietary models applicable to various DuPont products, including fluoroelastomers. Gilbert gives the general approach to formulation of such complicated models.[21] Particle formation by micellar entry. Figure 4.4 illustrates the micellar entry mechanism for particle formation, as described by Gilbert.[22] This mechanism is likely to prevail in systems with levels of added surfactant significantly higher than the critical micelle concentration. The initial steps are simi-

Figure 4.4 Particle formation by micellar entry.[22]

FLUOROELASTOMERS HANDBOOK lar to those for homogeneous nucleation, with formation of small radicals from initiator and monomer addition in the aqueous phase. When radicals reach the z-mer stage, they are readily incorporated into micelles. Even though a micelle is a dynamic moiety, with individual surfactant molecules residing in the micelle for only a short time, the micelle protects a growing radical from rapid termination with radicals in the aqueous phase. Also, the micelles solubilize monomers to facilitate rapid chain growth. Few radicals in the aqueous phase grow much longer than z-mer length before capture when micelles are present. Thus, homogeneous nucleation is unlikely when soap concentrations are well above the cmc. Micelles grow into mature polymer particles by radical propagation and coagulation with other particles. As the particle population and size grow, the surface area may become large enough to adsorb enough surfactant that the aqueous concentration falls below the cmc and micelles disappear. No new particles then can form by micellar entry, but homogeneous nucleation could occur when surfactant concentration falls to or below the cmc in the aqueous phase. Models that allow for both homogeneous nucleation and micellar entry generally predict a low particle number for soap concentrations below the cmc, then a large increase in the particle number as soap concentration is raised to and just above the cmc. However, most experimental data indicate a more gradual change in particle as the soap concentration is increased through the cmc. This suggests that,

4 PRODUCTION OF FLUOROELASTOMERS with homogeneous nucleation below the cmc, particles are more effectively stabilized against coagulation as surfactant concentration increases. Thus the particle number becomes relatively high as soap concentration is raised, well before the cmc is reached. Secondary nucleation. So-called secondary nucleation involves the formation of new particles in the presence of an established population of seed or previously formed particles. Gilbert[23] gives criteria for this situation. The number and size (thus the surface area) of established particles must be low enough that aqueous-phase radicals have sufficient probability of growing beyond the z-mer stage to jcrit size for nucleation. This case is important in continuous emulsion polymerization systems, which require continuing formation of new particles in the presence of a large number of particles present in the dispersion. Kinetics relationships. Complex models, such as those described by Richards, Congalidis, and Gilbert in Reference 20, can represent emulsion polymerization systems well, allowing extrapolation to conditions outside the range of available experimental data and providing insight into the effects of changing reaction variables. However, such models require considerable physical and kinetic data (e.g., solubilities of monomers in copolymers of varying composition over a range of temperatures and pressures, individual propagation rate coefficients and values of z and jcrit for oligomer entry and coagulation into particles). Such information has been obtained for only a few copolymers. Some parameter adjustment is usually necessary to fit experimental data. A particular difficulty seems to be prediction of both number-average molecular weight and particle number in a given system. It should be noted that both of these parameters are difficult to measure accurately so experimental error contributes considerably to differences from model predictions. In spite of the limited scope of the models developed so far, the models have helped workers understand the behavior of more complex terpolymer and tetrapolymer systems. Bonardelli, Moggi, and Russo[24] studied particle formation in the soapless emulsion polymerization of vinylidene fluoride (VDF) and hexafluoropropylene (HFP). Semibatch polymerizations were carried out in a five-liter reactor charged with 3.5 liters of water, using ammonium persulfate as initiator at

47 85°C with no added soap. Copolymer composition was held constant at a molar ratio VDF/HFP = 79/ 21, the same as most commercial dipolymers, by feeding this monomer mixture during polymerization. Reaction was stopped at 400 grams of polymer per liter of water (29% solids). Monomer concentration and initiator levels were varied in the study. Dispersion samples were taken during the polymerization for measurement of particle size by laser light scattering; the number of particles was calculated from average particle volume and total polymer formed. Experimental results were interpreted using Eq. (4.24), treating the constant copolymer composition as if it were a homopolymer. Monomer concentration [M] was expressed in terms of the product of average monomer fugacity fM and Henry’s Law constant H, so the rate equation becomes

Eq. (4.25)

Rp =

k p Hf M M o N p nr NA

It should be noted that the concentration of monomer in the aqueous phase as well as that in the polymer particles varies with monomer fugacity (or total monomer pressure). Thus, the aqueous oligomeric radical growth and polymerization rate in the particles are both affected by varying monomer fugacity. For this copolymerization system, Bonardelli and coworkers[24] observed very long nucleation periods, with the number of particles Np increasing up to about 200 grams polymer/liter (17% solids). The polymerization rate also increased during this period, corresponding to interval I. Nucleation periods were longer in experiments with lower monomer fugacity or higher initiator level. Even during interval II, when Np and Rp are essentially constant, further particle formation may occur if balanced by particle agglomeration. The polymerization rate Rp and final particle number Np in interval II varied about as expected with initiator concentration [I], with Rp ∝ [I]0.6 and Np ∝ [I]0.4. Variation with monomer fugacity was somewhat more difficult to explain, with Rp approximately second order in fugacity and final Np varying inversely with monomer fugacity. Bonardelli and coworkers account for this by noting that monomer concentration affects particle size and the number of radicals per particle nr. They rearrange Eq. (4.25) into the form

48

Eq. (4.26)

FLUOROELASTOMERS HANDBOOK

Rp N A Np fM

= k p HM o nr

This states that the polymerization rate per mole of particles divided by monomer fugacity is proportional to the number of radicals per particle. A plot of the left-hand side of Eq. (4.26) versus particle size indicates that nr is low and nearly constant at small particle size, but increases greatly with size at particle diameters above about 260 nm. At small sizes, particles would be expected to have either one or no radicals present because of rapid termination by incoming radicals, giving a 0,1 system with nr = 0.5. The more usual case for commercial VDF/HFP copolymerization with no soap (or low soap) is to have relative large particle sizes in the range 400 to 900 nm, and thus many radicals per particle. Consequently, we would expect a strong dependence of polymerization rate on monomer concentration in such systems. Also, initiation levels play a considerable role in determining rate and particle number. The hindered termination in large particles leads to significant broadening of molecular weight distribution in the absence of transfer agents. For production of commercial fluoroelastomers, empirical relationships are usually applied to estimate polymerization rates and to set and control polymer viscosities since most parameters in fundamental kinetics models are not known for most compositions. Polymerization rates may be correlated by equations of the form Eq. (4.27)

Rp = kp fMq ρ r(1 + S s)

Such equations may be applicable to VDF copolymerization with soap added at low concentration S. Monomer concentration may be represented by partial pressure or fugacity fM. An overall radical generation rate at 100% efficiency ρ is used, and an overall polymerization rate coefficient kp for the particular copolymer composition and reaction temperature. The usual ranges for the exponents are: q ~ 1–2, r ~ 0.5–0.7, and s ~ 0.4. It may also be necessary to incorporate additional factors to account for the effects of polymer concentration in the dispersion, or alternatively, for reaction time in a semibatch reactor or residence time in a continuous reactor. Ordinarily, Rp is known from experience and a commercial reactor is run at the same rate and

other conditions for a given product. Operating rates are often not set by kinetics, but are limited at lower levels because of other plant design constraints considered in Secs. 4.4.2 and 4.4.3. Relationships showing the dependence of polymer molecular weight or viscosity on reaction variables are of more use in setting and controlling fluoroelastomer properties. Number-average molecular weight Mn can be expressed as the ratio of polymerization rate (Rp g/h) to rate of chain formation (mol/h). For most fluoroelastomer emulsion systems, long chains are started and stopped by radical entry into particles (rate ρe), or by reactions with an added transfer agent (rate rtr). Ordinarily, transfer reactions with monomer, polymer, initiator, or adventitious impurities are negligible.

Eq. (4.28)

Mn =

Rp  ρe   + rtr   2 

A more convenient measure of molecular weight than Mn is desirable for routine monitoring of product. In most situations, molecular weight distribution is reasonably constant, and thus Mv/Mn can be assumed constant. For a given polymer composition and solvent, the limiting viscosity number or intrinsic viscosity [η] is related to viscosity-average molecular weight Mv by the Mark-Houwink equation:[25] Eq. (4.29)

[η] = K´ Mvα

For commercial VDF copolymers in a good solvent such as methyl ethyl ketone, the exponent α is in the range 0.55–0.75. A good approximation to [η] is the inherent viscosity or logarithmic viscosity number: Eq. (4.30)

ηinh = (ln ηr)/c

The relative viscosity ηr is measured as the ratio of solvent to solution efflux times in a capillary viscometer, with solution concentration c = 0.1 g/dL. The overall radical generation rate at 100% efficiency ρ is used instead of radical entry rate, so an empirical relationship for inherent viscosity then becomes

Eq. (4.31)

ηinh

Rp   =   K (ρ + 2rtr )

a

4 PRODUCTION OF FLUOROELASTOMERS

49

The parameters K and a can be determined for a given polymer composition by making a number of experimental polymerization runs at varying initiator levels without any transfer agents present. Equation (4.31) simplifies to

Eq. (4.32)

ηinh

 Rp   =   Kρ 

a

For analysis of experimental data, this can be put in the form

Eq. (4.33)

 Rp  log ηinh = a log  − a log K  ρ 

A plot of log ηinh versus log (Rp/ρ) has slope a, and K can be calculated from the intercept. With these parameters evaluated for a given copolymer composition, Eq. (4.32) can be used over a wide range of polymerization conditions with no transfer agent present. For the usual case of initiation by thermal decomposition of persulfate, ρ can be calculated from values of kd estimated from Eq. 4.16. To extend the correlation to include effects of transfer reactions, one must decide on an appropriate form to express the transfer rate rtr. The usual preference is for highly reactive transfer agents, so that transfer rate is proportional to feed rate of transfer agent Ftr. For VDF copolymers, transfer agents with active hydrogen are often used (e.g., low molecular weight alcohols, esters, or ketones). For such agents used at moderate levels at relatively high reaction temperatures (>100°C), Eq. (4.31) may be modified to the form

Eq. (4.34)

Rp   ηinh =    K (ρ + 2 K tr Ftr )

a

With K and a already evaluated as above for a system, experiments may be run with varying transfer agent feed rates to determine the transfer coefficient ktr. For evaluation of ktr from experimental data, Eq. 4.24 may be put in the form:

Eq. (4.35)

ηinh

−1 a

−

F Kρ = 2 Kk tr tr Rp Rp

The left-hand side of Eq. (4.35) is plotted versus Ftr /Rp to get a straight line (if the assumptions above hold), and ktr can be calculated from the slope. Polymerization conditions for which a given value of ktr applies are quite restricted. Transfer rates are not highly sensitive to temperature, so ktr may be approximately constant over a range of 10°C–20°C. However, transfer agents such as those listed above for VDF copolymers are soluble in both polymer particles and the aqueous phase. Thus, these agents distribute between phases, and the fraction in the polymer particles increases with increasing solids. Thus, Eq. (4.34) may apply to only a narrow range of dispersion solids. Alternatively, ktr will appear to vary with reaction time in a semibatch reactor or with residence time in a continuous reactor. For less reactive transfer agents that might be used in a semibatch reactor at low temperature, a correlation in the classical form[26] based on the ratio of transfer agent to monomer in polymer particles may be used to obtain transfer coefficients:

Eq. (4.36)

ηinh

−1 a

−

[T ] Kρ = C tr [M ] Rp

The applicability of these relationships for controlling product characteristics varies with the type of reactor system employed. Design, operation, and control of continuous and semibatch emulsion polymerization systems are considered in Secs. 4.4.2 and 4.4.3.

4.4.2

Continuous Emulsion Polymerization

DuPont pioneered VDF/HFP/(TFE) polymerization in continuous stirred tank reactors (CSTRs) in the late 1950s. An early version of a continuous fluoroelastomer production process, including isolation, is described by Bailor and Cooper.[27] Recent versions of the continuous emulsion polymerization process, as run by DuPont Dow Elastomers, feature more feed components, monomer recovery with continuous recycle of unreacted monomers, and considerably more monitoring and control systems. A schematic diagram of such a continuous polymerization system, including monomer recovery and recycle, is shown in Fig. 4.5. Details of monomer recovery are discussed in Sec. 4.7.

50 Continuous polymerization has the advantage of allowing sustained production at steady state. High rates are attained at moderately high dispersion solids (15%–30%). Most or all of the heat of polymerization is removed by the temperature rise of chilled feed water, so polymerization rates are not limited by relatively low rates of heat removal through a reactor cooling jacket. Continuous polymerization is particularly advantageous for production of a few high-volume types, especially if individual product campaigns are two days or more in length. After initial adjustments are made, uniform polymer can be produced at the same conditions for a considerable period. Continuous polymerization is less attractive for a product line comprising many types, requiring short campaigns with frequent reactor startups and shutdowns. Modern control systems allow rapid attainment of goal polymer characteristics and thus good quality even in this situation. However, semibatch systems are better suited to making product lines with many low-volume specialty types. The range of products suitable for a continuous emulsion polymerization process is somewhat restricted. Monomer compositions must allow aqueous-phase oligomerization rates high enough so that continuous generation of new particles occurs, and thus steady polymerization rates can be attained.

Figure 4.5 Continuous emulsion polymerization system.

FLUOROELASTOMERS HANDBOOK Reasonably high radical generation rates are required, with dispersion stabilization by ionic oligomers and added soap. Suitable compositions include most vinylidene fluoride copolymers, especially the commercially important VDF/HFP/(TFE) and VDF/ PMVE/TFE products. For continuous emulsion polymerization of these VDF copolymers, P. L. Tang has found that low levels of highly water-soluble short-chain hydrocarbon alkyl sulfonates (e.g., sodium octyl sulfonate) are effective in place of fluorinated soaps.[28] TFE/PMVE perfluoroelastomers and ethylene/TFE/PMVE base-resistant elastomers can also be made in continuous reactors, though at much lower rates. Sustained particle nucleation is difficult to attain for TFE/propylene compositions; these do not appear suitable for production in a continuous polymerization. Certain polymer designs that require initial formation of particles with little or no further initiation must be made in semibatch reactors. An example is the Daikin family of polymers with almost all chain ends capped with iodine, made in a living radical polymerization. Continuous reactor design and operation. Continuous stirred tank reactors used for emulsion polymerization of fluoroelastomers are run essentially liquid-full at pressures high enough to keep unreacted monomers dissolved in polymer particles.[29] Operating pressures are in the range 2–7

4 PRODUCTION OF FLUOROELASTOMERS MPa at temperatures 60°C–130°C. Most VDF copolymers are made at 5–7 MPa and 100°C–120°C with residence times of 10–60 minutes. Slower polymerizing specialties (e.g., TFE/PMVE and E/TFE/ PMVE copolymers) are made at low pressures and temperatures, with longer residence time (2–4 hours). Potential corrosion from dispersions with pH’s in the range 2–6 at elevated temperatures is avoided by stainless steel reactor construction. To facilitate rapid dissolution of feed monomers and good mixing of the dispersion, fairly intense agitation is necessary, usually with baffled turbine impellers. A number of inlets must be provided for various components. Gaseous monomers are usually introduced into regions of high shear near impeller tips. Especially for operation at short residence times, it is necessary for agitation systems to be designed with high impeller flow, so that liquid turnover times are much shorter than residence times. VDF copolymer dispersions are usually not highly stable, since it is desirable to minimize added soap which must be readily removed during isolation. Thus, the maximum shear rate or impeller tip speed must be limited to avoid shear coagulation. Dispersion exits the reactor through a back-pressure control valve. Stability of the dispersion must be high enough to withstand the high shear involved in the letdown to much lower pressure in the degasser. Removal of heat of polymerization is a major consideration in reactor design for fluoroelastomers. For specialty types such as perfluoroelastomers made at low rates and low temperatures in relatively small reactors, heat removal through a cooling jacket is feasible. VDF copolymers are generally made at much higher rates per unit volume and high overall rates that require larger reactors. Cooling jackets are inadequate in this situation, so such reactors are usually operated adiabatically, with the heat of polymerization taken up by the temperature rise of water fed to the reactor. Heat of polymerization calculated from bond energies is in the range 300–350 kcal/kg for commercial VDF copolymer compositions. For adiabatic operation, dispersion solids must be limited so that the ratio of water fed to polymer made is high enough to allow a reasonable temperature rise from a practical water feed temperature to the reaction temperature. For example, a practical VDF/HFP/TFE polymerization may be run at about 20% solids, with 4 kg water per kg polymer in the reactor dispersion. In this case, if the heat of poly-

51 merization is 320 kcal/kg, a water temperature rise of 80 degrees is necessary, so a reaction temperature of 110°C requires a water feed temperature of 30°C. Similar conditions are described in DuPont patent examples:[30] VDF/HFP (60/40 wt%) copolymer made at 107°C, 10–12 minutes residence time, 18% solids, with polymerization rate 1.1 to 1.3 kg/h·L. Operation of a continuous reactor is quite different from semibatch polymerization. CSTR startup procedures are crucial to proper operation. Aqueous feeds are first established to fill the reactor at the desired operating pressure and temperature. These feeds include the main water flow, initiator components, soap, and buffering agents. Other liquid feeds—cure-site monomer, chain-transfer agent—that may retard polymerization are usually withheld until reaction has been established. Polymerization is started by commencing monomer feed at full rate and calculated overall composition suitable for the copolymer being made. When the reaction starts, a considerable exotherm (“heat kick”) occurs, tending to increase the reactor temperature. Water feed temperature is reduced and jacket cooling may be applied to bring the reactor temperature back to goal. Polymer particles are formed quickly, but some oscillation of particle number occurs in the first few reactor turnovers. High monomer conversion (80%–95%) is attained within 1–2 turnovers when feeds and other operating conditions are properly set up. Steady-state operation at full dispersion solids concentration is established after about six reactor turnovers. Unreacted monomer recovered from degassing vessels is recycled back to the feed compressor and fresh feeds are adjusted to maintain the desired polymer composition and production rate. Monomer feeds to a CSTR are illustrated in Table 4.4 taken from Ex. 4 of Ref. 30 describing VDF/HFP copolymer production in a 10-gallon (38liter) reactor at 89% conversion. At steady state, with recycle set equal to unreacted offgas rate, the fresh feed rate and composition equals polymer rate and composition. The total monomer feed to the reactor remains constant throughout the operation. At startup, before any recycle is established, fresh feed must equal total feed. CSTR shutdown is accomplished by shutting off the monomer feeds. This immediately stops the polymerization, since the unreacted monomer mixture

52

FLUOROELASTOMERS HANDBOOK

Table 4.4 CSTR Monomer Mass Balance (from Ref. 30)

Monomer

Fresh feed (polymer)

Recycle (offgas)

Total feed

kg/h

%

kg/h

%

kg/h

%

VDF

24

60

1.25

25

25.25

56

HFP

16

40

3.75

75

19.75

44

Total

40

held up in the reactor is quite unreactive toward propagation. Initiator and chain-transfer agent flows are then stopped. The main water feed, including soap, is maintained long enough to displace remaining polymer dispersion from the reactor to the degasser and blend tank. Continuous emulsion polymerization control. Control of a continuous emulsion polymerization reactor involves a number of aspects including temperature, conversion stability, radical generation rate, polymerization rate, polymer composition, and polymer viscosity. These control issues are discussed below. Temperature control systems must be sufficiently robust to overcome the inherent instability of this type of CSTR. Polymerization rate Rp and monomer conversion are sustained by radical generation rate, which must be adequate to form new particles continuously, thus maintaining the particle population. Radical generation rate ρ, especially if based on persulfate thermal decomposition, is sensitive to temperature. Thus, a decrease in temperature decreases ρ, which in turn decreases Rp and heat generation, tending to further decrease temperature. The control system must be able to respond fast enough to overcome this sequence of events that could lead to loss of reaction. For an adiabatic reactor, the heat exchanger on the main water feed must be able to switch quickly from heating the feed to goal reactor temperature at startup to cooling the feed well below the reactor temperature to take up the heat of polymerization. Partially bypassing the exchanger may be a means to make such a rapid transition. The system must also respond rapidly to prevent decreases in reactor temperature. CSTR polymerization systems have two possible steady states—the desired high conversion state and a very low conversion state, with an unstable inter-

5.00

45.00

mediate region. Upsets such as loss of initiator or excessive feed of a retarder may cause a flip from high to very low conversion. The low conversion situation means unreacted monomer builds up in the reactor, causing poor agitation and excessive monomer flow to the degasser, leading to potential safety hazards. Recovery from such a low conversion state is accomplished by stopping monomer feeds, continuing aqueous feeds to displace unreacted monomer and refill the reactor, followed by correcting the problem that caused loss of reaction, and restarting the polymerization. As noted above, radical generation rate sustains the polymerization rate in a CSTR, supplying radicals to existing polymer particles, and renewing the particle population by supporting aqueous oligomerization for particle nucleation and stabilization. The ratio ρ/Rp determines the ionic end-group level in the polymer and is a major factor in setting polymer molecular weight. For the usual case of persulfate thermal decomposition, the overall radical generation rate ρ can be calculated for a CSTR with water volume Vr and total water volumetric feed rate Fw with initiator concentration [I]o by making a mass balance on initiator to get its concentration [I] in the reactor. Eq. (4.37)

Fw[I]o = Fw[I] + Vrkd[I] or

[I] = [I]o (1 + kd θ) The first order decomposition rate coefficient kd for persulfate can be estimated from Eq. (4.16) or Table 4.3. Reactor residence time θ is the ratio Vr /Fw of water volume in the reactor to water flow.

4 PRODUCTION OF FLUOROELASTOMERS The water volume Vr is less than the total reactor volume because of the presence of polymer and unreacted monomer. The total radical generation rate at 100% efficiency is then

Eq. (4.38)

ρ = 2kdVr [I] = =

2kdVr [I]o (1 + kd θ)

2k d θFI (1 + kd θ)

The molar feed rate of initiator FI is equal to Fw[I]o and kdθ/(1 + kdθ) is the fraction of initiator decomposed in a CSTR with residence time θ, operating at a temperature giving an initiator decomposition rate coefficient kd. The radical entry rate ρe is lower than ρ by an efficiency factor f:

Eq. (4.39)

ρe =

2 f kd θFI (1 + kd θ)

Radical entry efficiency is usually low in these systems, about 0.2 to 0.6, but is ordinarily not known, so overall ρ is used for practical correlations applied to reactor control. Polymerization rate and in turn monomer feed rate goals are set by estimates from kinetics models (see “Kinetics Relationships” in Sec. 4.4.1), empirical correlations (e.g., Eq. 4.27), or plant experience. Monomer feed adjustments may be necessary to get goal Rp and polymer composition. Reactor effluent samples may be analyzed to determine composition and dispersion solids. Several estimates of Rp can be made from CSTR monitoring the following: • Calculation from water feed rate and dispersion solids • Monomer mass balance from flow meters and GC analysis of fresh feed, recycle, total feed, and offgas monomer streams

53 Control actions are facilitated if Rp is set below the maximum possible for the goal polymer composition and molecular weight at the prevailing reactor temperature and pressure. Then the monomer conversion is high enough that the monomer concentration in the particles is below the solubility limit. In this situation, changing a variable in a direction that tends to reduce Rp and conversion results in an increase in monomer concentration that tends to offset the change in Rp. Then most individual control actions can be accomplished without significant changes in Rp or conversion. Polymer viscosity control is facilitated by the use of relationships such as Eq. (4.34), which can be used to set ρ and transfer agent feed rate Ftr in ratio to Rp to get the desired ηinh. The ratio ρ/Rp sets the ionic end-group level in the polymer; this in turn affects bulk viscosity and bisphenol curing characteristics. Usually, ηinh is monitored from analyses of effluent samples. Then Ftr can be adjusted from correlations like Eq. (4.34) to get the desired polymer viscosity. Reactor dynamics must be taken into account in managing such control actions, since a change in a reactor input variable takes about six turnovers (6θ) to be fully reflected in dispersion effluent analyses. Dispersion stability is affected by soap feed rate, ρ, and pH. Base or buffer feed is set as a ratio to ρ, with adjustments made in response to pH measurements on effluent dispersion. With proper setup of polymerization conditions, control actions taken after startup should be only small adjustments. Redundant measurements of reactor variables (e.g., monomer flow and composition) are desirable to allow checking for instrument errors. Besides the measurements taken around the reactor used for direct polymerization control, monitoring of many other systems—monomer feed and recycle compressors, degassers, agitators, impurities in feeds, and leaks—is necessary for safe, smooth operation.

• Heat balance on an adiabatic reactor Monomer mass balances also provide estimates of polymer composition. The total monomer feed composition may be adjusted to obtain goal polymer composition. Cure-site monomer feed is usually set in ratio to Rp or total gaseous monomer feed, and cure-site level is monitored by analysis of effluent polymer.

4.4.3

Semibatch Emulsion Polymerization

All fluoroelastomer producers use semibatch emulsion polymerization systems. Detailed descriptions of commercial fluoroelastomer semibatch systems are not available in the open literature, but

54 smaller scale reactors are described in a number of patents. Figure 4.6 is a schematic representation of a fluoroelastomer semibatch reactor with associated charging and feed systems, and monomer recovery system. Shown are components usually charged initially, and those that may be fed during the course of the polymerization. Semibatch polymerization is suitable for a wide range of compositions, including those having very slow polymerization rates. Semibatch reactors are more versatile than continuous reactors for making specially designed polymers. Feeds of initiator, transfer agents, and cure-site monomers can be varied during the course of a batch to make polymers with different molecular weights and molecular weight distributions, end groups, and curesite distribution along chains. This allows control of rheology, processing, and curing behavior to an extent not attainable in CSTRs. Polymer composition and polymerization rate are readily controlled by setting monomer feeds during the reaction. Commercial semibatch reactors are capable of making a considerable number of low volume specialty products. However, the necessity of keeping different products separate in downstream handling equipment limits the versatility of the reactor system.

Figure 4.6 Semibatch emulsion polymerization system.

FLUOROELASTOMERS HANDBOOK Semibatch reactors have limitations compared to continuous reactors in the production of high-volume, fast-polymerizing types. Heat of polymerization must be removed by means of a cooling jacket. With this limited cooling capability, polymerization rates must be limited well below those possible in adiabatic CSTRs for many important high-volume products (e.g., VDF copolymers containing 60-80 mole % VDF). In campaigns of high-volume types, many batches with attendant shutdowns and startups are required, and batch-to-batch variability may be significant. For many types, reaction times may be too short to allow monitoring of product characteristics, feedback, and adjustments within each batch. Adjustments can be made on subsequent batches, but large blend tanks may be required to reduce final product variability. Holdup of gaseous monomer mixtures in semibatch reactors and feed systems is greater than that in CSTR systems. Considerable volumes of monomer mixtures under pressure in semibatch reactor vapor spaces and in accumulators after compressors may present potential explosion hazards. The lower operating pressures of semibatch reactors somewhat offsets this hazard, compared to

4 PRODUCTION OF FLUOROELASTOMERS CSTRs. However, barricades around semibatch reactors and feed facilities may be necessary to protect personnel. Semibatch reactor design and operation. Semibatch reactors are generally run at lower temperature and pressure than CSTRs. Usual ranges for semibatch operation are 60°C–100°C and 1–3 MPa (150–450 psi). Reaction times required to get dispersion solids of 25%–35% are quite variable, depending on composition and other variables related to polymer design, and may range from 2 hours to as much as 40 hours. Usually, the volume of aqueous dispersion is 60%–85% of total reactor volume. Dispersion volume increases significantly during the course of polymerization because of the increasing volume of polymer swollen with monomer. The general procedure for operation of a semibatch reactor is as follows: The reactor is charged with water and soap solution, and with monomers of the composition necessary to be in equilibrium with the desired polymer composition. Usually the unreacted monomer mixture from a previous batch makes up the bulk of the monomer charge. Ordinarily, this initial feed would bypass the accumulator after the compressor. The reactor is brought to the desired operating temperature and pressure. Reaction is started by adding persulfate initiator and chain-transfer agent. During polymerization, monomers are fed at the desired polymer composition to maintain reactor pressure. Additional initiator, transfer agent, cure-site monomer, and buffer may be fed during the polymerization as necessary to make the desired polymer. In semibatch emulsion polymerization of fluoroelastomers, particle formation occurs during the early part of the polymerization, but may be prolonged to rather high solids concentrations. With the increase in number of particles and growing radicals, the polymerization rate may also increase over a considerable fraction of the reaction time. To handle the large differences in monomer feed rate necessary to match the varying polymerization rate, an accumulator may be used between the feed compressor and reactor. The accumulator is maintained in a pressure range above the reactor pressure. A monomer mixture of the desired polymer composition is fed from the accumulator to maintain constant reactor pressure. Monomers may be fed periodically through the compressor to keep the accumulator in a set pressure range. This arrangement

55 allows metering of the monomers at convenient rates for accuracy in setting composition. The use of an accumulator does add a significant volume of highpressure monomer mixture to the feed system. This may be a potential explosion hazard for some monomer mixtures. Careful investigation is necessary to determine the extent of such hazards and provide means of avoiding damage or injury from possible deflagration of monomer mixtures. When the desired amount of polymer has been made, as estimated from the cumulative amount of monomer fed during the polymerization, shutdown is accomplished by stopping the feeds of monomer, initiator, and other minor components. Monomer may be removed by venting directly from the reactor. However, with the limited head space in this vessel, foaming and dispersion carryover into vapor lines can be a severe problem. It is more feasible to transfer the dispersion from the reactor to a larger degassing and blend tank. If the same composition is to be made in the next batch, it is convenient to leave a heel of dispersion in the reactor, along with the remaining unreacted monomer in the vapor space. This facilitates recharging and startup of the next batch. Commercial semibatch reactors used for manufacture of fluoroelastomers are generally 1,000 to 12,000 liters in size, larger than the CSTRs described in the previous section. Relatively small sizes are used for fast-polymerizing high-volume VDF copolymers, while larger reactors may be used for specialty types with lower polymerization rates. For copolymers of 60–80 mole % VDF with HFP and TFE or PMVE and TFE, rates may be limited by heat transfer capability. This situation can be analyzed by reference to Fig. 4.7, which shows a jacketed cylindrical reactor with diameter D, total height HT, and dispersion depth HL to get dispersion volume VL and heat exchange area A:

Eq. (4.40)

VL = ðD 2 H L 4

Eq. (4.41)

A = π DHL

Consider the case of a reactor with total heightto-diameter ratio HT/D = 1.85, 83% full of dispersion, and thus with liquid height HL = 1.5D. Then, from Eq. 4.40, the liquid volume is given by VL =

56

FLUOROELASTOMERS HANDBOOK

Figure 4.7 Semibatch reactor: heat exchange area and liquid volume.

1.5πD 3/4, and the diameter can be expressed in terms of the liquid volume by D = (4VL/1.5π )1/3. The heat exchange area, from Eq. 4.41, can be expressed as A = 1.5πD 2, or related to liquid volume as A = 1.5π(4VL/1.5π)2/3 = 4.23VL2/3. For the situation with the maximum rate of polymerization limited by heat transfer capability, the following relationships apply:

Eq. (4.42)

Rp max =

=

UA∆t ∆hp

4.23U∆t VL ∆hp

2/ 3

In Eq. 4.42, Rp max is the maximum polymerization rate for a polymer with heat of polymerization ∆hp in a reactor with heat exchange area A, overall heat transfer coefficient U, maximum average temperature difference between dispersion and jacket coolant ∆t, and dispersion volume VL. The maximum rate is proportional to the heat exchange area, thus to the two-thirds power of dispersion volume (or reactor volume). These relationships can be used to approximate the scale-up situation for semibatch reactors making polymer compositions for which rates are limited by heat exchange capabilities. A reasonable base case is that of a 1,500-liter reactor, charged with 1,000 liters of water, with capability of making 400

kg of VDF copolymer (28.6% solids in the dispersion after degassing) in two hours reaction time, thus Rp max = 200 kg/h. Assuming the monomer-swollen polymer has density 1.6 kg/liter, polymer volume is 250 liters and total dispersion volume, VL, is 1,250 liters or 1.25 m3, corresponding to 83% full. With HL/D = 1.5, D = 1.02 m from Eq. (4.40) and A = 4.89 m2 from Eq. 4.41, ∆hp = 320 kcal/kg or 1.34 MJ/kg and maximum ∆t = 50 K, which corresponds to a reaction temperature of 80°C and average coolant temperature of 30°C. The overall heat transfer coefficient U is 260 kcal/m2·h·K or 1.1 MJ/ m2·h·K, a reasonable value. Now consider scaling up this polymerization to a reactor eight times the size (12,000 liters) to make 3,200 kg polymer per batch. For the large reactor, VL = 10 m3, D = 2.04 m, and A = 19.6 m2, even with the optimistic assumption that U will be the same for the large reactor, the fourfold increase in heat exchange area limits the maximum rate to 800 kg/h, so that the reaction time increases twofold to four hours. This is probably a good tradeoff for scaling up, since total batch cycle time for the large reactor to make 3,200 kg would be much less than the total time required for eight batches in the small reactor. Offsetting the advantage of the larger reactor would be the cost of scaling up feed equipment, downstream blending, and isolation capacity. The larger monomer volumes under pressure may also introduce severe explosion hazards for the larger reactor. Design considerations for semibatch reactors differ significantly from those for continuous reactors. Since polymerization rates per unit volume are lower in semibatch reactors, these are usually much larger than continuous reactors. Pressures and temperatures are usually lower in semibatch reactors. Intensity of agitation is ordinarily lower, since high shear regions are not necessary to disperse monomers and other feeds to a semibatch reactor. Agitation systems should be designed for reasonable liquid turnover, with minimal baffling to avoid elastomer agglomeration and fouling. The presence of a sizeable volume of monomers under pressure in the head space of the reactor creates the potential for explosion hazards. Care must be taken to preclude possible sources of ignition, such as rubbing of moving metal parts, presence of air or other initiators, and electrical arcs or sparks. Proper relief area must be provided, which is capable of relieving the overpressure from a deflagration in the vapor space. For some

4 PRODUCTION OF FLUOROELASTOMERS monomer mixtures, this consideration may limit the reactor pressure or size. Feed systems for semibatch operation involve a combination of initial charging of some components and of feeding components at variable rates during polymerization. These requirements will be discussed in the next section. Semibatch emulsion polymerization control. Basic control of semibatch systems for making older VDF-based copolymer and terpolymer products is somewhat simpler than control of continuous reactor systems. However, new products require complex schemes for operation of the semibatch polymerization reactor to get the desired processing and curing characteristics. Major requirements of a semibatch reactor control system include: accurate initial charging of ingredients, good control of feeds of major monomers and minor components during polymerization, and maintaining the reactor at goal temperature and pressure. Before charging, it is necessary to clear air from the reactor system by flushing with inert gas, evacuation, or displacement of vapor with water. The proper amount of water (usually 50%–70% of total reactor volume) is charged along with dispersant (usually soap and buffer), and the reactor contents are heated to the desired polymerization temperature. Monomer is then charged with the appropriate composition to be in equilibrium with the desired polymer composition, and in an amount to bring the reactor to a chosen pressure at goal temperature. Major monomer composition is checked by gas chromatography. Polymerization is started by adding initiator. Then a monomer mixture with a composition essentially the same as the desired polymer composition is fed at a rate to maintain goal reactor pressure. Jacket coolant temperature is adjusted to keep the reactor at goal temperature as polymerization proceeds. Additional initiator is usually fed to hold the radical generation rate in a range that will maintain the polymerization rate and attain the desired polymer molecular weight and ionic end-group level. A transfer agent may be added to control the polymer’s molecular weight and molecular weight distribution. A cure-site monomer may be fed in ratio to the main monomer feed. Depending on reactor size and the polymerization rate, feeds of minor components may require special metering equipment to deliver low flows or small incremental shots accurately. Both instantaneous rates and cumulative amounts of ma-

57 jor monomers and minor components need to be monitored. The polymerization rate and total polymer formed are estimated from major monomer feeds. Note that the polymerization rate and the monomer feed rate may vary considerably over the course of a semibatch polymerization. An accumulator between the feed compressor and reactor may be necessary to facilitate delivery of a controlled monomer composition, especially during the early stages of the reaction when rates may be low. Polymerization is stopped by shutting off the monomer feeds when a desired dispersion-solids level is reached or a desired polymer viscosity is attained, both estimated from cumulative monomer feed. Reactor sampling may be feasible for relatively slow polymerizations with long enough reaction time to allow adjustments of feeds. The vapor space may be monitored by gas chromatography. Dispersion sampling may be difficult, especially in the usual situation of a barricaded reactor system precluding operating entry. Often the polymer characteristics must be inferred from monitoring of feed components during the polymerization. A number of strategies may be used for addition of initiator, transfer agent, and cure-site monomer components during a semibatch emulsion polymerization. The simplest initiator feed method is to add all of it at the start of polymerization. In this case, the total moles of persulfate initiator, I, in the reactor decrease with time, t, according to first order thermal decomposition kinetics: Eq. (4.43)

dI/dt = -kdI

Eq. (4.44)

It = I0 exp(-kdt)

Total radical generation rate, ρ t, at time, t, is given by Eq. (4.45)

ρ t = 2kdIt = 2kd I0 exp(-kdt)

In a semibatch emulsion polymerization, radical entry efficiency varies considerably as the particle population builds up. Since the efficiency is not readily estimated, it is easier to use total generation rate for correlation and monitoring purposes. The cumulative number of moles of radicals generated from time 0 to time t is Eq. (4.46)

Σρt = 2I0 [1- exp(-kdt)]

58

FLUOROELASTOMERS HANDBOOK

This method of adding initiator all at once may be usable for some semibatch polymerizations carried out at relatively low temperatures, say 80°C or below, with a persulfate initiator half life of two hours or more. The relatively high radical generation rate at the start facilitates particle formation, and the slowly decreasing radical generation rate may adequately sustain polymerization in later stages. However, this method is not versatile enough to control the polymerization rate, molecular weight, and end groups for most products of interest. A second method, often used for small reactors, is to add incremental shots of initiator to keep the initiator level between chosen levels, I0 and It, at intervals of time, t. The increment size, ∆I = I0 – It, is readily calculated from Eq. 4.44. Corresponding radical generation rates and cumulative radicals are estimated from Eqs. 4.45 and 4.46. For larger reactors, initiator may be fed continuously to get a desired profile of radical generation rate versus time, thus optimizing polymer viscosity and ionic end-group level, taking into account changes in polymerization rate over the course of the reaction. Initiator feed, FI, can be chosen to obtain constant, increasing, or decreasing ρ. For constant initiation rate, FI, is set equal to the initiator decomposition rate so that It = I0; then FI = kd I0 and ρ = 2kd I0. For the more general case, the following relationships apply:

Eq. (4.47)

Eq.(4.48)

dI = FI − kd I dt

I t = I 0 exp(− k d t ) + FI

[1 − exp(− kdt )] kd

Eq. (4.49) ρ t = 2k d I t

= 2kd I 0 exp(− kd t ) + 2 FI [1 − exp(− k d t )]

Eq. (4.50)

 F  Σρt = 2 I 0 − I [1 − exp(− k d t )] + 2 FIt kd  

Note that Eq. 4.50 can be applied to a number of intervals with varying initiator feed rates to get an overall summation of radicals generated over the course of the reaction. Chain-transfer agents are often used to control the molecular weight of fluoroelastomers. However, chain-transfer correlations and predictions are less readily obtained for semibatch systems than for continuous polymerization systems. Basic relationships like Eq. 4.31 are difficult to apply to semibatch systems. For transfer agents with low reactivity at the relatively low temperatures normally used in semibatch polymerization, Eq. 4.37 may be usable. This relationship is based on the ratio of transfer agent to monomer in particles. The transfer agent level in particles may not be readily estimated for agents that have substantial solubility in water because they are distributed between the aqueous and polymer phases. For some fluoroelastomer compositions, hydrocarbons may be used as transfer agents. These may be volatile enough to monitor by gas chromatography analysis of the vapor phase in the reactor. Such transfer agents are not usually used for VDF-containing polymers, because the hydrocarbon radicals formed by transfer are much less reactive toward propagation than the fluorocarbon radicals, thus retarding polymerization. Highly reactive transfer agents (e.g., lower alcohols or esters) may be fed continuously in set ratio to the monomer feed or the radical generation rate to get the desired polymer viscosity. However, while most of the chaintransfer agent reacts immediately in continuous systems operating at higher temperatures, that assumption can not be made for semibatch systems. Thus, considerable small scale polymerization work is often necessary to establish how to charge and/or feed transfer agents to obtain the desired polymer viscosity and molecular weight distribution for each composition. In a special case of transfer in semibatch emulsion polymerization, perfluorocarbon diiodides are used to make fluoroelastomers that have narrow molecular weight distribution and iodine at most chain ends for curing. As originally developed by Daikin workers,[31] a “living radical” polymerization is set up with very low levels of initiation and termination, so that propagation and transfer predominate. Soap levels are set high enough to obtain a large population of small particles containing no more than one growing radical each. Ordinarily, all of the diiodide

4 PRODUCTION OF FLUOROELASTOMERS transfer agent is added soon after polymerization starts, so that very few chains form without iodine end groups. Iodide ends, whether on polymer chains or the original perfluorocarbon iodide, continue to undergo transfer. Individual chains grow until they undergo transfer; the resulting iodide may transfer subsequently to allow further propagation and an increase in molecular weight. Since most chains start near the beginning of the polymerization, and very little radical-radical termination occurs, the chains have equal opportunity to grow. The result is a polymer with a very narrow molecular weight distribution and with iodine on most chain ends. Molecular weight continues to increase as polymerization proceeds; it can be estimated from the ratio of cumulative monomer feed to moles of iodide charged. Polymerization is stopped by shutting off the monomer feed when the estimated molecular weight goal is attained. In these polymerizations, adventitious impurities that may transfer to form unreactive radicals must be minimized. Even so, small amounts of initiator must be added from time to time to sustain the radical population and desired polymerization rate. It is crucial that a known amount of iodine is charged initially to allow an adequate estimation of molecular weight. Since these polymerizations are slow, it may be possible to take dispersion samples for measurement of the polymer’s inherent viscosity. A plot of inherent viscosity versus cumulative monomer feed may then be used to estimate the cumulative monomer level that will give the desired final viscosity. Most cure-site monomers are incorporated into the polymer at low levels. For many of these monomers, conversion is high, so they are not charged initially, but are fed in controlled ratio to the major monomers fed during the reaction. In a few cases, cure-site monomers may also be charged along with the initial monomer charge. Cure-site monomers, with active groups such as iodine or bromine, used for free radical curing present special problems in semibatch polymerization. Unlike the situation in continuous systems with continuous removal of polymer from the reactor, all chains formed in semibatch systems stay in the reactor until shutdown. This means that incorporated monomer units with reactive cure sites are exposed to radicals for considerable periods of time. The resulting chain transferto-polymer reactions may lead to excessive branching and gel formation, which may be detrimental to

59 processing characteristics. This situation has been circumvented in recent developments (e.g., by Ausimont workers)[32] by using small amounts of iodine-containing olefin monomer in conjunction with perfluorocarbon diiodide transfer agent. This allows production of fluoroelastomers with iodine units incorporated along the chains as well as at chain ends. Chain branching can then be controlled to allow reasonable polymer rheology and compound processing characteristics. A preferred Ausimont process variant for attaining reasonably high polymerization rates is a microemulsion process. A stable emulsion of perfluoropolyoxyalkalene solvent stabilized with a perfluoropolyoxyalkalene carboxylate surfactant is charged initially with monomers to obtain a large number of small particles and a subsequently high polymerization rate.

4.5

Suspension Polymerization

Suspension polymerization is used to make a number of thermoplastic polymers. In suspension polymerization, all reactions are carried out in relatively large droplets or in polymer particles stabilized by a small amount of water-soluble gum. Organic peroxide initiators are used to generate radicals within the droplets. A solvent may be used to dissolve a monomer at relatively high concentration. The main advantages of suspension polymerization over emulsion systems are that no surfactants, which are difficult to remove from the product, are used, and no ionic end groups are present which may be unstable during processing at high temperatures. What follows is a general introduction of suspension polymerization; S. Ebnesajjad[33] has presented an extensive review of suspension polymerization of vinylidene fluoride. In one semibatch suspension process for making VDF homopolymer,[34] the reactor is charged with water containing a cellulose gum (about 0.03%) as the suspending agent, an initiator solution, and a VDF monomer. The initiator of choice is diisopropyl peroxydicarbonate, which has a half life of about two hours at 50°C. The jacketed reactor is heated with agitation to a temperature in the range 40°C to 60°C, with a pressure in the range 6.5 to 7.0 MPa maintained by adding additional water or monomer

60 during the polymerization period of about 3.5 hours. Chain-transfer agents may also be fed. Average particle diameter is typically about 0.1 mm for the dispersion obtained in suspension polymerization. At the end of polymerization, the reactor is cooled, the dispersion is degassed by letting off pressure from the reactor, the polymer is separated by filtering or centrifuging the dispersion, and washed to remove residual dispersion stabilizer. Major features of this process were adapted by workers at Asahi Chemical Industry Co., Ltd. to make VDF/HFP/(TFE) fluoroelastomers. In the initial version of the Asahi Chem suspension polymerization process,[35] a relatively large amount of an inert solvent, trichlorotrifluoroethane (CFC-113, CCl2F–CClF2), is dispersed in water containing 0.01%–0.1% methyl cellulose suspending agent. The mixture is heated under agitation to the desired polymerization temperature (usually 50°C) and the proper composition of VDF/HFP/(TFE) monomer mixture to make the desired copolymer is charged in the amount necessary to get the goal concentration in the monomer-solvent droplets. With the solvent used, the pressure is usually relatively low, about 1.2–1.6 MPa. Reaction is started by adding diisopropylperoxydicarbonate initiator solution and a monomer mixture, with composition essentially that of the polymer being made, is fed to maintain the reactor pressure constant. Polymerization starts in the monomer-solvent droplets, with initial formation of a low molecular weight fraction. As polymerization proceeds, viscosity of the particles increases, long-lived radicals form, and both polymerization rate and molecular weight increase with reaction time. The resulting polymer has a bimodal molecular weight distribution, with the minor low molecular weight fraction acting as a plasticizer for the bulk high molecular weight polymer. Normally no chain-transfer agents are used for polymers cured with bisphenol. Polymer viscosity is set from the ratio of total polymer formed to initiator charged. Since reaction times are fairly long (six hours or more) to attain high dispersion solids (30%–40%), dispersion samples can be taken from the reactor during polymerization to monitor inherent viscosity and predict when to stop polymerization for goal viscosity. After polymerization is stopped by turning off the monomer feed, monomers are removed by venting the reactor. Considerable care is necessary during this operation to reduce pressure in stages so

FLUOROELASTOMERS HANDBOOK that rapid release of monomer from particles does not occur, and carryover of particles into vapor lines is avoided. Particle sizes after degassing are 0.1 to 1 mm in diameter, and are readily separated by filtering or centrifuging the dispersion. Fluoroelastomers made by the suspension process have no ionic end groups and contain a significantly low molecular weight fraction. These copolymers can be made with high inherent viscosities for enhanced vulcanizate properties, while they still retain good processibility because their compounds have relatively low viscosity at processing temperatures. Compared to emulsion products of similar composition, bisphenol-curable suspension products exhibit better compression set resistance, faster cure, and better mold release characteristics. Asahi Chem also developed peroxide-curable VDF/HFP/TFE fluoroelastomers by charging methylene iodide along with the initiator to the suspension polymerization reactor. The resulting chaintransfer reactions allow incorporation of iodine on more than half the chain ends. Final polymer molecular weight is determined mainly by the ratio of total monomer fed during the polymerization to iodine incorporated. The suspension process has been adapted to make bimodal VDF/HFP/TFE polymers for extrusion applications, such as automobile fuel hoses, to get smooth extrudates with minimal die swell at high shear rates.[36] These polymers contain 50%–70% very high molecular weight fractions (ηinh about 2.5 dL/g, Mn about 106 daltons) and 30%– 50% very low molecular weight fraction (ηinh about 0.15 dL/g, Mn about 17,000 daltons), with polymer bulk viscosity determined by the relative amounts of the two fractions. The low viscosity fraction has a molecular weight below the critical chain length for entanglement (Me about 20,000 to 25,000), so it acts as a plasticizer to facilitate extrusion with low die swell. Similar bimodal polymers with low viscosity fractions having molecular weights greater than Me would exhibit very high die swells. Synthesis of these polymers is carried out in two stages of suspension polymerization. A very small amount of initiator is used in the first stage to make the high molecular weight fraction. Then additional initiator and a relatively large amount of methylene iodide are charged to make the low viscosity fraction. The relative amounts of each fraction are estimated from the cumulative monomer feed in each stage. The amount of methylene iodide charged is that required to in-

4 PRODUCTION OF FLUOROELASTOMERS corporate 1.5%–2% iodine in the low viscosity fraction. Polymerization rate in the second stage is very low, so the total reaction time required for the bimodal polymer synthesis is some 40–45 hours. These bimodal polymers are ordinarily cured with bisphenol, but the iodine ends on the low viscosity fraction allow a mixed cure system with both bisphenol and radical components. The radical system links very short chains into longer moieties that can be incorporated into the bisphenol crosslinked network. Similar bimodal polymers made by emulsion polymerization with conventional chain-transfer agents are cured only with bisphenol. The resulting vulcanizates contain sizeable fractions of short chains that are not incorporated into the network and are thus susceptible to extraction when exposed to solvents. The suspension process described above was used by Asahi Chem for commercial production of Miraflon fluoroelastomers during the early 1990s. However, it was recognized that the use of large amounts of the ozone-depleting solvent CFC-113 would need to be phased out. A second version of the suspension process uses a small amount of a hydrogen-containing solvent such as HCFC-141b, CH3-CFCl2. Since only enough solvent is used to dissolve the initiator, the reactor operating pressure must be increased to 1.5–3.0 MPa so that a fraction (10–30%) of the initial monomer charge condenses to form an adequate volume of droplets to serve as the polymerization medium. In a further improvement, the hydrochlorofluorocarbon solvent is replaced with a small amount of a water-soluble hydrocarbon ester, preferably methyl acetate or t-butyl acetate.[37] These polar hydrocarbon solvents are used mainly to feed the initiator to the reactor. The methyl or tbutyl groups are relatively inactive toward transfer, and these solvents are so soluble in water that little is in the polymer phase. After the Asahi Chem suspension polymerization technology was acquired by DuPont in 1994, additional development was carried out to extend the technology to VDF/PMVE/ TFE fluoroelastomers with cure-site monomers incorporated along the chains.[38] Cure-site monomers can be incorporated evenly along chains by careful feed in controlled ratio to polymerization rate of major monomers. In this way, bromine- or iodine-containing monomers can be incorporated, in addition to iodine on chain ends from methylene iodide transfer agent, to get polymers with improved characteristics in free radical cures. It should be noted that simi-

61 lar polymers can be made more readily by continuous emulsion polymerization.[39] Of more interest are bisphenol-curable VDF/PMVE/TFE compositions with 2H-pentafluoropropylene, CF2=CH–CF3, as cure-site monomer. Bisphenol-cured parts from such polymers have better thermal stability than products made by radical curing.

4.5.1

Polymer Compositions

The suspension polymerization process works well for VDF/HFP/TFE and VDF/PMVE/TFE compositions. These monomer mixtures exhibit high propagation rates at relatively low temperatures (45%–60°C) and low monomer concentrations (less than 15% in monomer/polymer particles). Reasonably high polymerization rates are possible at temperatures below 60°C, so elastomer particle agglomeration is minimized. The amorphous polymers are insoluble in the monomer/solvent mixtures and also the monomer and solvent have low solubility in the polymer-rich phases. The high viscosity of the polymer-rich phase gives hindered termination, so that long-lived radicals can grow to high molecular weights. The initial monomer mixtures charged to the reactor can be partially condensed at about 50°C and moderate pressure to form droplets as the initial locus of polymerization, without the need for charging large amounts of solvent or for charging polymer seed particles. Slower propagating compositions like TFE/ PMVE give a lower molecular weight and a less useful polymer when made by suspension polymerization than polymer that can be obtained by emulsion polymerization. For these perfluoroelastomers, monomer solubility in the polymer is high, so particle viscosity remains too low for hindered termination and the formation of long-lived radicals. Considerable initiator must be fed during the polymerization to sustain reasonable reaction rates. Several other TFE copolymer compositions give similar results.

4.5.2

Polymerization Mechanism and Kinetics

In all versions of the suspension-polymerization process, an initial dispersion of low-viscosity droplets is present, either from solvent containing dissolved monomer or from liquid monomer partially

62

FLUOROELASTOMERS HANDBOOK

condensed from the initial monomer charge. With the low viscosity of the monomer-solvent phase and the relatively high initial radical flux, both initiation and radical-radical termination rates are high, so the polymer formed in the early stages of the reaction is low in molecular weight. Solution kinetics apply in this early stage. The general reaction scheme outlined in Sec. 4.3.1, describing initiation, propagation, and termination reactions (Eqs. 4.1, 4.2, and 4.4) can be used in this situation. In the mobile droplets, rates of radical generation and termination are equal: Eq. (4.51)

2f kd[I] = 2kt[R·]2

Radical concentration in the droplets can be expressed as

Eq. (4.52)

  [R ·] =  f k d [I ]  kt 

12

The polymerization rate, Rp, and the numberaverage molecular weight Mn (assuming termination by radical combination) are then given by:

Eq. (4.53)

 f k [I ] Rp = k p [M ][R ·] = k p [M ] d   kt 

Eq. (4.54)

Mn =

12

k p [M ]

( f kd k t [I])1 2

The high termination rate coefficient, kt, leads to a low rate and molecular weight in this initial stage of suspension polymerization. As the reaction proceeds, the insoluble polymer formed builds up as a second high-viscosity phase in the droplets. Radical mobility is limited in this viscous polymer-rich phase, so termination rate decreases and both molecular weight and polymerization rate increase with time. In the later stages of polymerization, kt approaches zero. Long-lived radicals persist in the dominant viscous polymer phase, so that growth of these chains continues even though most of the initiator has decomposed and the new radical formation rate is low. Ordinarily, the initial low molecular weight polymer is a small fraction of the total polymer formed.

When methylene iodide is used to form iodine end groups for radical curing, initiator levels are minimized so that transfer reactions predominate. Depending on iodide level, polymerization rates may be quite low, even in the later stages of the reaction. Ordinarily, all the methylene iodide is charged with the initiator. Since the iodide is somewhat soluble in water, its level in the droplets is initially low enough so the polymerization can be started at a reasonable rate. As the reaction proceeds, all the iodide enters the droplets and undergoes transfer. As in the semibatch emulsion case with perfluorinated iodide as the transfer agent, chains undergo alternating periods of propagation interrupted with iodide transfer from other chain ends. Usually the suspension polymers made with methylene iodide contain no more than about 1.5 iodine ends per chain and have somewhat broader molecular weight distribution than semibatch emulsion polymers made with perfluorinated iodides and very low initiation levels. The suspending agent, usually a water-soluble gum such as methyl cellulose with moderate molecular weight, prevents agglomeration of droplets and monomer-swollen polymer particles by forming a water-swollen coating on them. These gums are effective at low concentrations, typically less than 0.1% concentration in the water charged. Also polymerization temperature must be less than about 70°C so the swollen elastomer particles are not too sticky. Cellulose derivatives contain structures that normally would participate in chain-transfer reactions. However, these materials are so water-soluble that essentially none is in the droplets or polymer particles, thus do not reduce polymer molecular weight. The initiator of choice for fluoroelastomer suspension polymerization is diisopropyl peroxydicarbonate (or isopropyl percarbonate, IPP), R–O– C(:O)–O–O–C(:O)–O–R, where R is isopropyl. Under polymerization conditions, the IPP added to the reactor is dissolved in the fluorinated monomer/ polymer droplets, and its half-life is about 2.5 hours (kd = 0.27/h) at 50°C. IPP decomposition by thermal homolysis gives isopropyl carbonate radicals, R– O–C(:O)–O·, which react readily with fluorinated monomers to initiate polymerization. In the absence of a reactive monomer, the isopropyl carbonate radicals may undergo further decomposition to isopropoxy radicals, R–O·, and carbon dioxide. Isopropoxy radicals may react with IPP to induce

4 PRODUCTION OF FLUOROELASTOMERS further decomposition. The IPP decomposition rate varies with the medium, and increases significantly in polar solvents. Thus solutions must be kept cold and used soon after makeup. IPP is supplied as a solid (m.p. 8°C–10°C) which must be stored in a dedicated freezer at temperatures below –20°C. Above –10°C, IPP decomposes slowly, but generates heat internally so that the temperature may increase rapidly and the decomposition autoaccelerates. Decomposition products include flammable vapors which may be ignited. Proper storage and handling procedures are necessary to avoid these problems.

4.5.3

Reactor Design and Operation

A reactor used for the suspension polymerization of fluoroelastomers must be designed to minimize agglomeration of swollen particles and fouling of vessel surfaces. Agitation must be sufficient to disperse the initial condensed monomer-solvent phase into small droplets and to keep polymer particles from settling. Standard turbine agitators may be used with minimal baffling that is sufficient to avoid vortex formation without producing regions of high turbulence. Reactor fouling must be monitored and removed periodically. This maintains heat removal capacity through the cooling jacket and allows adequate temperature control. Removal of polymer deposits is facilitated by ports for water jets. As with emulsion semibatch reactors, vessel size must accommodate a considerable increase in volume of the liquid phase as reaction proceeds to high solids. Typically, the initial aqueous solution charge occupies about 60% of the vessel volume. The final dispersion, containing up to about 40% polymer, may occupy some 80%–85% of total volume. If degassing is carried out by letting down reactor pressure after completion of a batch, enough vapor space must be allowed to minimize entrainment of particles in the vapor stream vented from the reactor. This ordinarily requires a ratio of length-to-diameter of about two for the vessel. Adequate relief area should be provided for the vapor space to avoid damage from potential monomer deflagration. As with semibatch emulsion polymerization, monomer feed rates for a suspension reactor may vary over a wide range during the course of each batch operation. An accumulator may be necessary between the feed compressor and reactor to facili-

63 tate metering, as discussed in semibatch reactor design and operation. Careful measurement of initiator, modifier, and cure-site monomer feeds is also necessary. Special design considerations apply to storage and handling of peroxydicarbonate initiator, as noted in Sec. 4.5.2.

4.5.4

Polymerization Control

Similar polymerization control considerations apply to semibatch suspension systems as those described in semibatch emulsion polymerization control. Reference 38 describes suspension polymerization system operating and control procedures for making two fluoroelastomers of different compositions: one is a VDF/HFP/TFE polymer with a bromine-containing cure-site monomer and iodine end groups for peroxide curing, and the other is a VDF/ PMVE/TFE polymer with a cure-site monomer for bisphenol curing. In both cases, a 40-liter reactor was configured for carrying out semibatch polymerizations. The gaseous monomer feed system consisted of a source line for each gaseous monomer, a compressor, an accumulator, and a pressure controller between the accumulator and reactor vessel. At the beginning of the polymerization, monomers were consumed in the reactor at a low rate. The monomer supply rate to the compressor was considerably higher to maintain an accurate monomer composition. The difference in the amount of monomer fed to the compressor and the amount consumed in the reactor was stored in the accumulator. The storage in the accumulator was controlled by a pressure controller, which was cascaded to several flow controllers metering the monomer mixture to the compressor. As monomers flowed into the accumulator, the pressure increased to a high preset limit. When the high limit was reached, the flow controllers closed the gaseous monomer feed valves. As monomers flowed into the reactor, the accumulator pressure dropped to a low limit. At the low limit, the monomer supply valves opened and compressed gases were fed to the accumulator until pressure reached the high set limit, which shut off the monomer feed. This cycle continued until the polymerization was terminated. An exponential digital filter was used to calculate the average flow rate of gaseous monomers during each period that the supply valves were in the open position. The calculated average gaseous monomer flow rates were used to adjust

64

FLUOROELASTOMERS HANDBOOK

the flow rate of the metering pump delivering the liquid cure-site monomer to the reactor during the same time periods. For the peroxide-curable VDF/HFP/TFE elastomer, the 40-liter reactor was charged with 20 liters of water containing 14 g (0.07%) methyl cellulose (Mn about 17,000 daltons) and was heated to 50°C. Gaseous monomers were charged as listed to bring the reactor pressure to 2.56 MPa: Monomer

Amount, g

Wt %

TFE

183

6.3

VDF

872

29.8

HFP

1,870

63.9

Total

2,925

Part of the monomer charged condensed under these conditions to form liquid droplets. The polymerization was initiated by adding a solution of 20 g diisopropyl peroxydicarbonate (IPP) in 80 g methyl acetate. A solution of 36 g methylene iodide in 44 g methyl acetate was also charged to the reactor; about a third was added at the start and the rest during the feed of the first 1,800 g of incremental monomer. A gaseous incremental major monomer mixture was fed to maintain constant reactor pressure at the controlled temperature of 50°C. The liquid cure-site monomer, 4-bromo-3,3,4,4-tetrafluorobutene-1 (BTFB), was fed in a controlled ratio into the incremental gaseous monomer feed. BTFB was initially fed at a ratio of 0.35% to the digitally filtered value of monomer flow. The ratio was gradually increased to 0.75% to attain an overall average of 0.60% BTFB, based on the total incremental monomer fed. The polymerization rate was approximately equal to the incremental monomer feed rate, and increased from approximately 100 g/h initially to 1,000 g/h after 10 hours. A total of 14,278 g incremental monomer was fed over a 20-hour period in the amounts shown:

ery was 15.4 kg, corresponding to 43% solids in the dispersion. Major monomer composition in the polymer was determined by FTIR, and bromine and iodine cure-site levels by x-ray fluorescence. Polymer composition was 22.1% TFE, 51.4% VDF, 25.7% HFP, 0.54% BTFB, and 0.20% I, close to the goal composition set by incremental monomer feeds. Polymer inherent viscosity was 0.73 dL/g, Mooney viscosity ML-10 (121°C) was 42, and glasstransition temperature, Tg, was -19°C. The addition of the cure-site monomer BTFB in a closely controlled ratio to the incremental monomer feed allowed the polymerization to proceed at a satisfactory rate to form a high molecular weight polymer having a homogeneous distribution of cure sites for good curing characteristics. For the bisphenol-curable VDF/PMVE/TFE elastomer, the 40-liter reactor was charged with 20 liters of water containing 14 g methyl cellulose and heated to 50°C. Gaseous monomers, including the cure-site monomer 2H-pentafluoropropylene (2HPFP), were charged in the amounts listed to bring the reactor pressure to 1.55 MPa: Monomer

Amount, g

Wt %

TFE

45

3.0

VDF

405

27.0

PMVE

600

40.0

2H-PFP

455

30.0

Total

1,505

The polymerization was started by adding an initiator solution of 40 g IPP in 160 g methyl acetate. A gaseous incremental monomer mixture was fed to maintain constant pressure at 50°C. The gaseous cure-site monomer, 2H-PFP, was fed along with the major monomers. The incremental feed rate, approximately equal to the polymerization rate, increased from about 176 g/h initially to about 1,956 g/h at the termination of the polymerization period of 10.7 hours. A total of 12,000 g incremental monomer was fed:

Monomer

Amount, g

Wt %

TFE

2,736

19.2

VDF

7,056

49.4

Monomer

HFP

4,486

31.4

TFE

480

4.0

Total

14,278

VDF

6,960

58.0

PMVE

4,320

36.0

240

2.0

The polymerization was terminated after 20 hours by discontinuing the incremental monomer feed. After degassing, the resulting polymer slurry was filtered and washed. Total dry polymer recov-

2H-PFP Total

Amount, g Wt %

12,000

4 PRODUCTION OF FLUOROELASTOMERS

65

After termination of the polymerization by discontinuing the incremental monomer feed, the polymer slurry was degassed, filtered, and washed. Total polymer recovery was 12.0 kg, corresponding to 37% solids in the dispersion. Polymer composition and properties are listed, with the ratio of 2H-PFP to PMVE determined by 19F nmr: Inherent viscosity, dL/g Mooney viscosity, ML-10 (121°C)

0.81

4.6.1

Molecular Weight Distribution

43

Composition, wt % TFE

3

VDF

59

PMVE

36

2H-PFP

2

Glass transition temperature, Tg, °C –31 Curing characteristics and physical properties of cured compounds were determined for the medium-viscosity bisphenol-curable polymer above and a high-viscosity peroxide-curable commercial polymer made by continuous emulsion polymerization. The commercial polymer, Viton GLT®, has a composition 10% TFE, 54% VDF, 35% PMVE, and 1.2% BTFB, and has inherent viscosity about 1.3 dL/g, and a Mooney viscosity ML-10 (121°C) about 90. As shown in Table 4.5, cure rates and physical properties are similar, but the bisphenol-cured compound gives much better mold release and better retention of properties after heat aging at 250°C. Peroxide Luperox 101XL is 2,5-dimethyl-2,5di(t-butyl peroxy)hexane, 45% on an inert filler. Tremin EST is an epoxysilane-treated wollastonite mineral filler. This formulation, with the special filler molecular sieve zeolite, and metal oxides (but no calcium hydroxide), is advantageous for bisphenol curing of VDF/PMVE/TFE elastomers containing the reactive 2H-PFP cure-site monomer.

4.6

ably by choice of polymerization process and operating conditions. The nature of chain end groups, determined by initiation and transfer reactions, may affect both processing and curing behavior. Polymer composition and monomer sequence distributions affect suitability for various end uses.

Process Conditions and Polymer Characteristics

Processing behavior, curing characteristics, and vulcanizate physical properties of fluoroelastomers are largely set by polymerization process conditions. Molecular weight distribution is important for most polymer compositions, and can be varied consider-

Little information on molecular weight distribution of commercial fluoroelastomers has been published. The usual method of size exclusion liquid chromatography (SELC; also known as gel permeation chromatography, GPC) is not easy to apply. SELC measures macromolecule size in solution, which varies with polymer composition as well as molecular weight. Reliable calibrations exist for only a few VDF copolymer compositions. Several TFE copolymers are so resistant to fluids that solvents suitable for SELC measurements are not available. However, some generalizations can be made, especially for VDF/HFP/TFE and VDF/PMVE/TFE fluoroelastomers, on the variation of molecular weight distribution with polymerization process condition. For these polymer families, average monomer unit weight is about 100 daltons, and polymers with low to medium-high bulk viscosities have a number-average molecular weight, Mn, in the range 60,000 to 120,000 daltons corresponding to 600 to 1,200 monomer units per chain. Bulk characteristics such as viscosity are related to weight-average molecular weight, Mw, which varies from 1.2 to 8 or more times Mn, depending on the distribution set by the polymerization process and operating conditions. Older products, such as Viton® A and B, made by the original DuPont continuous emulsion polymerization process with no added soap or transfer agents have relatively broad molecular weight distribution, with Mw/Mn about 4 to 8. The large particles (about 1 µm in diameter) contain many growing radicals. Termination is hindered, but may involve a combination of long-chain radicals as well as a combination of long-chain radicals with entering oligomeric radicals, leading to broad distribution. A similar semibatch operation, with low soap and use of an initiator level to set overall polymer viscosity, also results in broad molecular weight distribution. Such polymers and their compounds have high green strength and modulus, but poor extrusion characteristics.

66

FLUOROELASTOMERS HANDBOOK

Table 4.5 Comparison of Curing Characteristics and Physical Properties[38]

Formulation, phr Polymer Tremin 283600 EST filler

GLT

Suspension Polymer

100

100

45

45

MT Black, Thermax FF N990

2.5

2.5

Calcium oxide VG

–

6.0

MgO, Elastomag 170

–

1.0

Molecular sieve 13X

–

3.0

Bisphenol AF

–

2.0

Tetrabutyl ammonium hydrogen sulfate

–

0.5

Ca(OH)2, Rhenofit CF

5

–

Peroxide, Luperox 101XL 45

2

–

Triallyl isocyanurate, Diak 7

4

–

GLT

Suspension Polymer

Process aid, octadecyl amine, Armeen 18

0.5

–

Process aid, rice bran wax, VPA 2

1.0

1.0

ML, dN·m

3.9

2.2

MH, dN·m

22.9

23.8

Formulation, phr

Cure Characteristics (MDR, 180°C)

ts2, minutes

0.52

0.29

t´50, minutes

0.93

0.42

t´90, minutes

2.74

2.70

Tensile Properties M100, MPa

14.3

8.2

TB, MPa

18.5

12.0

EB, %

153

176

Hardness, Shore A

75

74

Compression set (disks), % (70 h @ 200°C)

32

37

4 PRODUCTION OF FLUOROELASTOMERS Newer types made by either continuous or semibatch emulsion polymerization use added soap to get smaller particle size and chain-transfer agents to control polymer viscosity. These have narrow molecular weight distribution, with Mw/Mn about 2–3. Such polymers and their compounds exhibit relatively low green strength and modulus, but have good flow and extrusion characteristics. Perfluorocarbon diiodide modifiers in semibatch emulsion systems with very low initiator levels may attain “living radical” polymerizations, resulting in fluoroelastomers with very narrow molecular weight distributions, Mw/Mn about 1.2–1.5.[40] Other iodidemodified polymers made with higher initiator levels and optional cure-site monomers in continuous or semibatch emulsion systems have somewhat broader molecular weight distributions, with Mw/Mn about 1.8–2.5.[41] When bromine- or iodine-containing curesite monomers are incorporated in fluoroelastomers made by continuous emulsion polymerization with little or no added chain-transfer agents, these reactive sites may undergo transfer and branching reactions. The long chain branches give considerable high molecular weight fractions, and broad distributions,

67 with Mw/Mn about 4–8. Extensive branching and gel formation may occur in semibatch polymerization, since all polymer made stays in the reactor until polymerization is stopped. Such highly branched, broad distribution polymers give marginal to poor processing characteristics. Figure 4.8 illustrates characteristic molecular weight distributions produced by the three process variations described for polymers made with iodide transfer and/or bromine-containing curesite monomers. Operating conditions in continuous emulsion polymerization or semibatch emulsion or suspension systems can be manipulated to get tailored bimodal molecular weight distributions. To obtain a bisphenol-curable VDF copolymer with good processing characteristics, a blend of a major modified low-viscosity (LV) component with a high-viscosity (HV) component is made by cyclic operation of a single continuous emulsion polymerization reactor.[42] HV component is made with a low persulfate initiator level for a period of at least six reactor turnovers; then a chain-transfer agent is fed for a longer period of time to make the LV component. HV and LV periods alternate in a series of cycles of several hours

Figure 4.8 Fluroelastomer molecular-weight distributution.

68

FLUOROELASTOMERS HANDBOOK

each, with conditions otherwise set to maintain a nearly constant polymerization rate and polymer composition. Effluent dispersion from the reactor is blended in tanks downstream before isolation of the bimodal polymer. Operation of a semibatch reactor is readily adapted to making bimodal polymers (see Sec. 4.5 for an example involving suspension polymerization). The reactor is started up with a low initiator level to make the HV component; then a transfer agent is fed to make the LV fraction desired.

4.6.2

End Groups

Three kinds of end groups are important for fluoroelastomers: ionic, nonionic, and reactive ends. The types of chain ends may largely determine the product processing and curing characteristics. The process variations discussed in the previous section give varying molecular weight distributions and also result in different end groups. Ionic end groups form from the inorganic initiators used in emulsion polymerizations. Transfer reactions with anionic soaps may also contribute to ionic end groups. Persulfate initiation results in a mixture of sulfate and carboxylate end groups in VDF copolymers, or in carboxylate end groups in TFE/ PMVE perfluoroelastomers. Redox systems, such as persulfate-sulfite, give sulfonate end groups. These ionic end groups increase the bulk viscosity of polymers and compounds by forming ionic clusters that act as chain extenders or temporary crosslinks. The effects are larger for polymers with higher fluorine content. Perfluoroelastomers made with full redox initiation and no chain-transfer agents contain sulfonate ends, which form clusters that are stable at the usual processing temperatures. The compounds are very difficult to mix and form into parts. VDF copolymers made with high persulfate initiator levels may have enough ionic end groups to interfere with bisphenol curing. The ionic ends tend to tie up variable fractions of the quaternary ammonium or phosphonium accelerators used, leading to variable cure rates. Residual soap and oligomers with ionic ends may also affect bisphenol curing. Ionic ends have little effect on radical curing, but these acidic ends may cause some premature decomposition of the organic peroxides used for curing. Ionic end groups contribute to compression set of o-ring seals. Ionic ends may be labile enough to form clusters when the seal is under strain

at high temperature. When the seal is cooled, the secondary network of ionic clusters prevents full recovery of seal shape and sealing force. Nonionic end groups form from the use of organic chain-transfer agents in emulsion polymerization, or from organic peroxide initiators used in suspension polymerization. Fluoroelastomers with mostly nonionic end groups have lower bulk viscosity, lower green strength of uncured compounds, and lower modulus and tensile strength of vulcanizates compared to similar composition with predominately ionic end groups. The polymers with nonionic end groups exhibit better compound flow and bisphenol cure characteristics. Compression set resistance is improved, since the nonionic ends do not impede shape recovery on relief of strain. Reactive ends are mainly formed from use of iodide transfer agents. When enough iodide end groups are present, the chains can be linked by attachment of multifunctional crosslinking agent to chain ends. The resulting networks can attain very good compression set resistance in seals.

4.6.3

Composition and Monomer Sequence Distributions

In the usual operation of a continuous or semibatch reactor, the monomer feed composition is essentially constant, and the reactor contains a constant composition of unreacted monomer. Under these conditions, copolymer composition is constant, with a very narrow overall composition distribution. However, the same copolymerization kinetics (reactivity ratios) that determine overall polymer composition as described in Secs. 4.3.2 and 4.3.3 also allow for the presence of monomer sequences that may differ considerably from the overall average composition. The fraction and length of certain monomer sequences may affect polymer characteristics such as the tendency to crystallize. Reactor operation may also be manipulated to produce blends of different compositions or block copolymers containing segments of different compositions within the same chain. Both of these situations are discussed in this section. W. Ring[43] calculated monomer sequencing in dipolymers by considering the relative probabilities of each monomer adding to a given radical end. The probability P11 of Monomer 1 adding to a radical ending in a Monomer 1 unit is given by:

4 PRODUCTION OF FLUOROELASTOMERS

69

k11 [M 1 ] P11 = k11 [M 1 ] + k12 [M 2 ]

tially amorphous and where they have significant crystallinity. For VDF/HFP copolymers, Sec. 4.3.3 notes that, to a good approximation, the HFP monomer does not add to a radical ending in an HFP unit, so r2 = 0 and the copolymer composition relationship reduces to Y = r1X + 1. The monomer addition probabilities P11 and P12 given by Eqs. 4.55 and 4.56 can then be expressed in terms of polymer composition Y, the ratio of VDF to HFP units in the copolymer:

Eq. (4.55)

=

r1 X r1 X + 1

Similarly, the probability P12 of Monomer 2 adding to a Monomer 1 radical end is:

Eq. (4.56)

P12 = =

k12 [M 2 ] k11 [M 1 ] + k12 [M 2 ]

Eq. (4.59)

P11 =

Y −1 Y

Eq. (4.60)

P12 =

1 Y

1 = 1 − P11 r1 X + 1

The probability P1(n) of a sequence containing n Monomer 1 units is then: Eq. (4.57)

The bulky –CF3 of HFP is attached directly to the polymer chain, crowding adjacent groups to produce severe steric hindrance, and thus stiffens the chain to reduce segment mobility for 1–2 VDF units on either side of an HFP unit. Thus, a long sequence of some 12 VDF units seems to be the minimum length required for crystallization with other similar sequences. Using α = 12 in Eq. 4.58, crystallizable fractions for VDF/HFP copolymers of various compositions can be estimated, as shown in Table 4.6. The average VDF sequence length for each composition is Y. The last column gives an estimate of the maximum crystallizable fraction in each co-

P1(n) = P11n-1P12

The fraction Q1 of Monomer 1 units in sequences α or longer in length is: Eq. (4.58)

Q1 = αP11α-1 – (α – 1)P11α

The weight fraction of copolymer in the form of Monomer 1 sequences α or longer is w1Q1, where w1 is the total weight fraction of Monomer 1 in the copolymer. These relationships can be applied to fluoroelastomer families of interest to determine composition ranges where the copolymers are essen-

Table 4.6 Crystallizable Fractions of VDF/HFP Copolymers (α = 12)

Mol % VDF

100 w1, Wt % VDF

Y, VDF/HFP

P11

Q1

100 w1Q1, % cryst’n

70.1

50

2.34

0.573

0.013

0.6

74.1

55

2.86

0.651

0.043

2.4

77.9

60

3.52

0.716

0.104

6.2

71.3

65

4.35

0.770

0.200

13.0

84.5

70

5.47

0.817

0.327

22.9

87.5

75

7.03

0.858

0.474

35.6

90.4

80

9.38

0.893

0.628

50.3

93.0

85

13.28

0.925

0.773

65.7

70

FLUOROELASTOMERS HANDBOOK

polymer. Actual crystallinity would be less, and would depend on thermal history of the copolymer (e.g., rate of cooling from the melt, annealing time, and temperature). These calculations are in general accord with observations for various VDF/HFP copolymer compositions. Copolymers containing 60% or less VDF have little or no crystallinity, and are amorphous elastomers. Copolymers containing 65%– 70% VDF have significant crystallinity, with relatively low melting ranges (40°C to 80°C). At higher VDF contents, the copolymers behave as crystalline thermoplastics, with melting ranges increasing with VDF level (100°C to 140°C). Crystalline copolymers with high VDF contents have poor lowtemperature flexibility, even though the glass transition temperature of amorphous regions decreases with increasing VDF content. From Sec. 4.3.3 on reactivity ratios, composition relationships for TFE/PMVE perfluoroelastomers are approximated reasonably well by assuming r1r2 = 0.5. From Eq. 4.14, the following relationship for r1X can be substituted into Eq. 4.55 for estimating P11 values from polymer composition Y:

Eq. (4.61)

r1 X =

(

Y −1 + 1+ Y 2 2

to a partially crystalline polymer that gives vulcanizates with a high modulus, but poor low-temperature flexibility. Special reactor operating conditions may be set up to obtain blends or block copolymers with amorphous elastomer and crystalline thermoplastic components. An elastomer in powder form has been made in a two-stage continuous emulsion polymerization system.[44] In one example, an elastomeric VDF/HFP copolymer (58% VDF) was made in the first reactor at high conversion to minimize the amount of unreacted HFP. The total effluent dispersion, including the unreacted monomer, was fed to a second reactor along with the VDF monomer and additional aqueous feed containing initiator. A thermoplastic VDF/HFP component (about 91% VDF) was made in an amount about 29% of the total blend. The dispersion from the second reactor was flocculated and spray-dried to a fine powder. Since the monomer in the second reactor was soluble in the elastomeric particles, the thermoplastic component formed as a separate phase within the elastomer matrix. The composite product, containing about 68% VDF, exhibited a glass-transition temperature of -20°C, characteristic of the elastomeric component and a crystalline melting point of about 140°C, characteristic of the thermoplastic component. The blend was cured with bisphenol to obtain a vulcanizate with a higher modulus and tensile strength than that of the first-stage elastomer alone; elongation-at-break and compression set were comparable. Compared to a physical blend of VDF/HFP elastomer with commercial poly-VDF, the cascade blend gave vulcanizates with a lower modulus, higher elongation, and better compression set resistance. In the cascade reactor operation, relatively few active radicals of the elastomeric component enter the second stage to add thermoplastic chain segments in the same macromolecule. The blend consists mostly of separate chains of the two components.

)

12

The –O–CF3 group of PMVE does not hinder chain segment mobility greatly, with the flexible –O– linkage separating the bulky –CF3 group from the chain. Thus, relatively short TFE sequences are able to crystallize, and a value of α = 8 appears reasonable for the lower limit of crystallizable segment lengths. Estimates of crystallizable fractions for a few TFE/PMVE compositions are shown in Table 4.7. The first two compositions, with TFE content up to about 55%, are nearly amorphous, with little crystallinity likely. The third composition corresponds

Table 4.7 Crystallizable Fractions of TFE/PMVE Copolymers (α = 8)

Mol % TFE

100 w1, Wt % TFE

Y, TFE/PMVE

P11

Q1

100 w1Q1, % cryst’n

62.4

50

1.66

0.565

0.074

3.7

67.0

55

2.03

0.622

0.131

7.2

73.9

63

2.83

0.707

0.269

17.0

4 PRODUCTION OF FLUOROELASTOMERS The Daikin “living radical” semibatch emulsion polymerization process can be used to make block copolymers with segments of different composition.[45] An iodine-terminated VDF/HFP/TFE elastomeric component is made with perfluorocarbon diiodide and a small amount of initiator in a first stage of operation. Unreacted monomer is removed, the dispersion is recharged to the reactor, and polymerization is continued with VDF or TFE/E added to make thermoplastic chain segments attached to central elastomeric segments of block copolymer macromolecules. The copolymer can be compounded and cured by the usual elastomer processing techniques. However, it can also be molded as a thermoplastic at a relatively low temperature, then can be removed from the mold and optionally cured by raising the temperature of the part.[46] Adapting a similar diiodo transfer process, Carlson developed A-B-A segmented thermoplastic elastomers with compositions more resistant to strong base and solvents.[47] In one embodiment, the central elastomeric B blocks have the base-resistant composition E/TFE/PMVE, and the outer thermoplastic blocks are E/TFE. Uncompounded molded parts have good properties without curing, but may be cured by ionizing radiation for enhanced properties.

4.7

Monomer Recovery

In the continuous emulsion polymerization process, as shown in Fig. 4.5, pressure is let down at the reactor exit so that the unreacted monomer flashes in the line leading to a degassing vessel. A small amount of defoamer may be added to avoid entrainment and carryover of polymer dispersion from the degasser. Effluent from the degasser goes to a second vessel at a lower pressure to remove most of the rest of the monomer by diffusion from the small particles. The vaporized monomers may be recycled directly back to the suction of the reactor feed compressor. However, it is usually more convenient to take the unreacted monomers through a recycle compressor to a monomer recovery tank. The monomer can then be fed at a controlled rate from the recovery tank to the reactor feed compressor. Less volatile components in reactor efflu-

71 ent dispersion are usually not recovered in this process; they are removed in polymer drying. In semibatch polymerization processes, as shown in Fig. 4.6, the monomer is recovered after completion of the polymerization batch. It is possible to vent unreacted monomer directly from the reactor to a monomer recovery compressor and hold tank. However, control of foaming and carryover is difficult with the limited head space in the reactor. Usually, the dispersion is let down at a controlled rate to a degassing vessel maintained at a low pressure. If a polymer of a similar composition is to be made in the next reactor batch, a heel of dispersion plus a considerable fraction of the unreacted monomer may be left in the reactor. Monomer vaporized from the degasser goes through a compressor to a recovery tank. The degassing vessel may be heated to allow final monomer removal by unsteady state diffusion at low pressure. The recovered monomer is fed to the reactor feed compressor to provide a proper composition for starting the next polymerization batch.

4.8

Isolation

In fluoroelastomer emulsion polymerization processes, dispersions are stabilized by anionic soaps, oligomers, and end groups. Salts of aluminum, calcium, or magnesium are usually used to cause coagulation into particles of convenient size (about 1 mm diameter) for washing and separation by filtering or centrifuging. The coagulant metal ion is chosen for its effectiveness at low concentration and also to keep the soap in solution to facilitate its removal. Coagulation conditions (temperature, holdup, concentration) are controlled to get reliable crumb size for washing, separation, and drying. In the original DuPont continuous emulsion polymerization process for VDF/HFP/(TFE) elastomers, described in Ref. 27 and shown in Fig. 4.9, isolation is also a continuous operation. Potassium aluminum sulfate solution is added to the dispersion in an agitated tank to produce a slurry of crumb that is fed to a continuous centrifuge for removal of most soap and salts. Crumb from the centrifuge is suspended in fresh water in a second wash tank. The slurry is again centrifuged and the wet crumb is fed to a continuous-belt conveyer air oven dryer. Dry crumb is

72

FLUOROELASTOMERS HANDBOOK

Figure 4.9 Isolation by crumb washing and drying.

taken to a crumb blender, then fed to an extruder to produce the final form of pellets or sheet for packaging. Isolation of a polymer from a semibatch emulsion process is similar. Batch coagulation may be carried out by adding coagulant to the dispersion in a stirred tank. Polymer crumb may be separated by filtration or centrifuging, and washed to remove residual soap and salts before drying in an air oven or extruder. In a different version of a continuous isolation process,[48] polymer dispersion is pumped through a coagulation section to a dewatering extruder, as shown in Fig. 4.10. Coagulant is added in-line, and conditions are set to produce large polymer agglomerates. The extruder is set up in a vertical configuration with the inlet in the top section with a large diameter screw. Water containing residual soap and salts is removed from the top. The system is maintained under enough pressure to collapse vapor bubbles that could otherwise cause some polymer crumb to rise to the top water exit. The screw picks

up the polymer and compresses it in a metering section with a smaller diameter to force almost all of the water out of the top of the machine. Polymer with less than 5% water content exits the bottom outlet of the extruder. Final drying is carried out in a vented drying extruder. Since the dewatering extruder removes some 99% of the water in the original dispersion, most water-soluble soap and salts are also removed. Such a system is adequate for continuous emulsion polymerization systems using modest soap levels for dispersion stabilization. Extrusion isolation systems can also be used in semibatch emulsion polymerization processes. However, the higher soap levels used may necessitate a separate coagulation and crumb-washing step before extrusion. A major fraction of the bisphenol-curable VDF/ HFP/TFE fluoroelastomers produced is sold as a precompound, rather than a gum polymer. The isolated gum polymer from a process described above is sent to a compounding facility for incorporation of bisphenol crosslinking agent, accelerator, and optional

4 PRODUCTION OF FLUOROELASTOMERS

73

Figure 4.10 Extruder isolation system.

processing aids. The precompound compositions are usually proprietary, and are designed for specific end uses and fabrication methods. The advantage of precompounds to customers is that the supplier assures good dispersion of curatives and reproducible processing characteristics. Conventional rubber compounding equipment is used, usually an internal mixer and a sheet extruder.

4.9

Process Safety

The major hazards in fluoroelastomer production processes involve handling of toxic or potentially explosive monomer mixtures. Hazards relating to individual monomers are discussed in Ch. 3. In some cases, mixtures may be less hazardous than one or more of the monomers present. For example, the explosive potential of TFE or VDF is reduced in mixtures containing HFP or PMVE. In other cases, mixtures may be more energetic than the individual monomers (e.g., TFE with olefins such as propylene or ethylene). Explosivity testing is necessary to establish the explosion potential of various mixtures at conditions encountered in production facilities. Such testing can be used to establish ratios of required pressure relief areas to volumes of monomer under pressure. Tests can also establish ranges of

monomer composition, pressure, and temperature that can be allowed in plant operation. Systems designed for VDF/HFP copolymerization may not be suitable for TFE/propylene polymerization, for example. In addition to proper design of relief systems, it may be necessary to provide additional protection to personnel by barricading some systems to avoid consequences of possible compromising of relief devices by polymer plugs. Volumes of monomers under pressure should be minimized in monomer feed and polymerization reactor systems. This may be difficult for semibatch systems, as discussed in semibatch reactor design and operation Sec. 4.4.3. Propagation of deflagration pressure pulses from one vessel to another should be prevented by proper placement of relief devices and by minimizing line sizes. Potential ignition sources for monomer deflagration should be minimized by proper design of the system and by proper operating procedures. Electrical systems should not produce arcs or sparks, and surface temperatures should be limited. Electrical energy in instruments should be lower than levels necessary for ignition of monomer mixtures. Metal parts of moving equipment such as agitators should be designed to avoid metal-to-metal contact that could produce sparks or hot surfaces. Trace oxygen levels in monomers should be monitored, and operating steps should be taken to remove oxygen

74 and air from the systems. Trace oxygen can lead to initiation of polymerization through formation and decomposition of monomer peroxides. Polymerization in high-pressure monomer feed systems can give plastic compositions that can cause plugging or local hot spots that might initiate deflagration. Monomer piping should be as direct as possible, avoiding sharp elbows and tees to closed pipe sections, with dead volumes that cannot be readily flushed. In addition to having operating procedures set up to avoid monomer hazards during normal production operation, adequate procedures for equipment maintenance and modification are needed. A large fraction of mishaps causing injury or equipment damage have occurred during mechanical maintenance rather than production operation. Special attention must be paid to assuring adequate flushing and clearing of equipment before mechanical work is started. Similar attention is necessary when putting equipment back into service, especially in careful removal of air before introducing monomers. A number of toxic materials are present in a fluoroelastomer production facility. Very low exposure limits have been established for several major fluoromonomers. Monitoring of work areas is necessary to detect leakage of gaseous monomers, so that steps can be taken to limit exposure of operators to potentially toxic levels. Handling of minor liquid components, such as bromine- or iodine-containing cure-site monomers and transfer agents, may require special procedures and personal protective equipment. For some materials, toxicity information may be limited; these should be handled by procedures adequate to protect personnel from exposure. Peroxide initiators should be handled by procedures recommended by their suppliers to avoid potential hazards caused by decomposition in storage or contact with readily oxidized materials. Considerations for storage and handling of peroxydicarbonates are discussed in Sec. 4.5.2. Monomer compressors should be carefully monitored and controlled to avoid condensation between stages because of the potential for equipment damage or release of excessive amounts of monomers from relief devices. Maximum temperatures should be kept well below those at which monomer decomposition can occur. Trace oxygen levels should be monitored and controlled to avoid possible polymerization in compressor systems which have the potential to plug or initiate monomer deflagration.

FLUOROELASTOMERS HANDBOOK In continuous emulsion polymerization at normally high conversion, loss of reaction (e.g., by interruption of initiator feed or by introduction of a retarder) may lead to the rapid buildup of monomer mixtures with an increased explosivity hazard and with volume flows above the handling capacity of the downstream degassing equipment. Quick action is required to shut off the monomer feeds and to clear the monomers from the reactor by continuing the water feed. The reason for the loss of reaction should be established and corrected before restarting with the normal operating procedure. Proper design and operating procedures are necessary to assure the safe operation of other equipment normally present in chemical process plants, including pumps, agitated vessels, conveyors, extruders, and the like. These will not be covered here.

4.10 Commercial Process Descriptions Commercial continuous fluoroelastomer production facilities used by DuPont Dow Elastomers have the general configuration depicted in Fig. 4.5 for continuous polymerization and monomer recovery, with isolation carried out either by crumb handling as shown in Fig. 4.9 or by extruder dewatering and drying as shown in Fig. 4.10. With the wide range of VDF/HFP/TFE and VDF/PMVE/TFE compositions made, polymerization rates per unit volume vary over a wide range. To keep the overall production rate in a reasonably narrow range for good operation and control, it is convenient to have more than one reactor size available in each facility. Then, a relatively small reactor can be used for products with high polymerization rates per unit volume, and a larger reactor is available for slower polymerizing types. This arrangement also allows for optimizing reaction conditions to get the desired polymer characteristics. Other considerations for design, operation, and control of continuous emulsion polymerization systems are discussed in Sec. 4.4.2 under the headings “Continuous reactor design and operation” and “Continuous emulsion polymerization control.” Monomer recovery and isolation systems are described in Secs. 4.7 and 4.8.

4 PRODUCTION OF FLUOROELASTOMERS Less information is available on the various semibatch process facilities operated by the other fluoroelastomer suppliers. Generally, polymerization system configurations are as shown in Fig. 4.6 and as described in Secs. 4.4.3, and 4.7 and 4.8. As in the continuous process, it may often be convenient to have reactors of different sizes available to accommodate the very wide ranges of polymerization rates per unit volume exhibited by different products. Previous discussion of major monomer handling has assumed that these monomers would be

75 fed as gases at temperatures well above critical temperatures for individual components or mixtures. It is also possible to keep the feed monomers in the liquid phase, as in some processes for making plastic TFE copolymers. Feed system pressures need to be high and temperatures low to keep monomers in liquid form. Such a system may be particularly useful for a product like the Daikin perfluoroelastomer, since the perfluoroalkyl vinyl ether used as the major comonomer is a liquid with a high critical temperature.

REFERENCES 1. Dostal, H., Monatsh. 69:424 (1936) 2. Alfrey,.T., Jr., and Goldfinger,G., J. Chem. Phys. 12:205 (1944) 3. Mayo, F. R., and Lewis, F. M., J. Am. Chem. Soc. 66:1594 (1944) 4. Simha, R., and Branson, H., J. Chem. Phys. 12, 253 (1944) 5. F. T. Wall, J. Am. Chem. Soc. 66:2050 (1944) 6. Walling, C., and Briggs, E. R., J. Am. Chem. Soc. 67:1774 (1945) 7. Moore, A. L., and Tang, W. K., U.S. Patent 3,929,934, DuPont Co., (Dec. 30, 1975) 8. Apotheker, D., and Krusic, P. J., U.S. Patent 4,035,565, DuPont Co., (Jul. 12, 1977) 9. Gilbert, R. G., Emulsion Polymerization – A Mechanistic Approach, Academic Press (1995) 10. Bovey, F. A., Kolthoff, I. M., Medalia, A. I., and Meehan, E. J., “Emulsion Polymerization” (1955) 11. Khan, A. A., U.S. Patent 4,524,197, DuPont Co., (Jun. 18, 1985) 12. Lyons, D. F., Moore, A. L., and Tang, P. L., U.S. Patent 6,774,164, DuPont Dow Elastomers LLC, (Aug. 10, 2004) 13. Gilbert, R. G., op .cit., pp. 51–53. 14. Gilbert, R. G., Particle Formation, op. cit., Ch. 7, pp. 292–342. 15. Gilbert, R. G., op. cit., p. 299. 16. Fitch, R. M., and Tsai, C. H., Polymer Colloids, (R. M. Fitch, ed.), Plenum, New York (1971) 17. Ugelstad, J., and Hansen, F. K., Rubber Chem. Tech. 49:536 (1976) 18. Richards, J. R., Congalidis, J. P. and Gilbert, R. G., J. Appl. Polym. Sci. 37: 2727 (1989) 19. Overbeek, J. T. G., Colloid Science, (H. R. Kruyt, ed.), Elsevier, Amsterdam (1960) 20. Richards, J. R., Congalidis, J. P., and Gilbert, R. G., ACS Symp. Series (Computer Applications in Applied Polymer Science), (T. Provder, ed.), Am. Chem. Soc., Washington, DC 404:360 (1992) 21. Gilbert, R. G., op. cit., 314–320 22. Gilbert, R. G., op. cit., 326 23. Gilbert, R. G., op. cit., 310–313 24. Bonardelli, P., Moggi, G., and Russo, S. Makromolekulare Chemie, Suppl. 10/11 11–23 (1985) 25. Billmeyer, F. W., Jr., Textbook of Polymer Science, 79–83, Interscience Publishers, New York (1965) 26. Billmeyer, F. W., Jr., op. cit., pp. 277–279.

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27. Bailor, F. V., and Cooper, J. R., U.S. Patent 3,536,683, DuPont Co., (Oct. 27, 1970) 28. Tang, P. L., U.S. Patent 6,512,063, DuPont Dow Elastomers LLC, (Jan. 28, 2003) 29. Rexford, D. R., U.S. Patent 3,051,677, DuPont Co., (Aug. 28, 1962) 30. Moore, A. L., U.S. Patent 3,839,305, DuPont Co., (Oct. 1, 1974) 31. Tatemoto, M., Suzuki, T., Tomada, M. , Furukawa, Y., and Ueta, Y., U.S. Patent 4,243,770, Daikin Kogyo Co., (1980) 32. Arcella, V., Brinati, G., Albano, M., and Tortelli, V., U.S. Patent 5,674,959, Ausimont S.p.a. (Oct. 7, 1997) 33. Ebnesajjad, S., Fluoroplastics, Melt Processible Fluoropolymers, Vol. 2, 84-88, William Andrew Inc., Norwich, NY, (2003) 34. Dumoulin, J., U.S. Patent 4,524,194, Solvay & Cie, (Jun. 18, 1985) 35. Hayashi, K., and Matsuoka, Y., U.S. Patent 4,985,520, Asahi Chemical Industry Co., Ltd. (Jan. 15, 1991) 36. Hayashi, K., Saito, H., and Toda, K., U.S. Patent 5,218,026, Asahi Chemical Industry Co., Ltd., (Jun. 8, 1993) 37. Hayashi, K., Hashimura, K., Kasahara, M., and Ikeda, Y., U.S. Patent 5,824,755, DuPont Co. (Oct. 20, 1998) 38. Duvalsaint, F., and Moore, A. L., U.S. Patent 6,348,552 B2, DuPont Dow Elastomers, L.L.C. (Feb. 19, 2002) 39. Moore, A. L., U.S. Patent 5,032,655, DuPont Co., (Jul. 16, 1991) 40. Tatemoto, M., and Morita, S., U.S. Patent 4,361,678, Daikin Kogyo Co., (Nov. 30, 1982) 41. Moore, A. L., U.S. Patent 5,077,359, DuPont Co., (Dec. 31, 1991) 42. Moore, A. L., U.S. Patent 3,839,305, DuPont Co., (Oct. 1, 1974) 43. Ring, W., J. Polymer Science, Part B, Polymer Letters 1, 323 (1963) 44. Moore, A. L., and Tang, W. K., U.S. Patent 3,929,934, DuPont Co., (Dec. 30, 1975) 45. Tatemoto, M., Suzuki, T., Tomoda, M., Furukawa, Y., and Ueta, Y., U.S. Patent 4,243,770, Daikin Kogyo Co. (Jan. 6, 1981) 46. Tatemoto, M., U.S. Patent 5,198,502, Daikin Kogyo Co. (Mar. 30, 1993) 47. Carlson, D. P., U.S. Patent 5,284,920, DuPont Co. (Feb. 8, 1994) 48. Covington, R. A., and Ekiner, O. M., U.S. Patent 4,132,845, DuPont Co., (Jan. 2, 1979); U.S. Patent 4,408,038, DuPont Co. (Oct. 4, 1983)

5 Cure Systems for Fluoroelastomers 5.1

Introduction

Elastomer cure systems are designed to give stable networks for good mechanical properties and environmental resistance comparable to that of the base polymers. In addition, cure kinetics must be controlled to get adequate processing safety (i.e., negligible crosslinking at temperatures of 100°C to 140°C). This allows for mixing of compounds on tworoll mills or in internal mixers, and for extrusion of rod or sheet preforms. At molding temperatures of 160°C to 200°C, an adequate delay is necessary for mold flow before onset of rapid crosslinking to a high state of cure. Compounds should be designed to facilitate good mixing, smooth extrusion, and clean demolding of cured parts. These cure system characteristics are also desirable for fluoroelastomers, but the nature of the polymers makes it difficult to attain all the desirable features noted above. Fluoroelastomers are designed for outstanding resistance to high temperature and aggressive fluids, so development of crosslinking systems with comparable environmental stability is a major challenge. In a fluorinated matrix, most cure system components have limited solubility and reactivities are often quite different from those in hydrocarbon elastomers. Polymer and cure system development for the various fluoroelastomer compositions should be carried out together to obtain compounds suitable for economical commercial production of parts. In most cases, the cure system used initially for each polymer family has been replaced or modified substantially to attain better processing and curing behavior and enhanced final product properties. This chapter discusses the major cure systems developed for four fluoroelastomer families: VDF/HFP/(TFE), VDF/PMVE/TFE, perfluoroelastomers, and TFE/olefin elastomers.

5.2

VDF/HFP/(TFE) Copolymers: Diamine, Bisphenol, Peroxide

Three major systems have been used commercially for curing of VDF/HFP dipolymers and VDF/ HFP/TFE terpolymers. Two systems are based on

dehydrofluorination of reactive HFP-VDF sequences to form double bonds in the polymer chains, followed by reaction of nucleophilic diamine or bisphenol to form crosslinks. For VDF/HFP/TFE elastomers with high fluorine content, peroxide or radical cure systems have been developed utilizing bromine or iodine cure sites.

5.2.1

Diamine Cure

The first practical cure system for VDF/HFP fluoroelastomers was based on diamine derivatives with magnesium oxide. The diamine served as both dehydrofluorinating agent and crosslinker, and the magnesium oxide took up the HF formed. Diamines such as hexamethylene diamine are too reactive at low temperature, so derivatives were devised to moderate the activity and allow acceptable processing safety. The most widely used derivative was the carbamate salt of hexamethylene diamine, +H3N– (CH2)6–NH–COO–, sold by DuPont as Diak No. 1 curative. A dicinnamylidene derivative (Diak No. 3) has also been used, ΦCH=CH–CH=N–(CH2 )6 – N=CH–CH=CHΦ, where Φ represents a phenyl group. The usual acid acceptor in the compound was MgO with relatively large particle size. Compounds were relatively simple, containing polymer, diamine, MgO, inert filler, and an optional processing aid. A typical dipolymer formulation is listed below: VDF/HFP Dipolymer

100

MT black (N990)

30

MgO (Maglite Y)

15

Diak No. 1

1.5

Processing Aid

1

MT black is often used as a non-reinforcing filler in fluoroelastomers. This carbon black is produced by a thermal process, and has relatively large particles with few reactive groups on surfaces. A typical processing aid is a wax such as carnauba wax that is somewhat incompatible with the fluoroelastomer at elevated temperature so that it migrates to interfaces and acts as a flow lubricant or mold release aid. The mechanism proposed for the diamine cure[1] involves reaction of the amine base with polymer chains to eliminate HF and form double bonds, followed by reaction of the nucleophilic diamine with

78

FLUOROELASTOMERS HANDBOOK

the double bonds to form crosslinks with imine structure. The exact nature of active sites in the chains or of the resulting crosslinks was not determined. Water formed from the neutralization of HF by MgO had to be removed by postcuring in an air oven. With water present in vulcanizates at high temperature, hydrolysis of crosslinks could occur, forming carbonyl structures on the polymer chains with regeneration of the amine crosslinking agent. Except for some use of Diak No. 3 in latex compounding, the diamine cure system is little used now. The system has considerable processing deficiencies, giving premature crosslinking (scorch) at 100°C to 140°C and relatively slow cures at molding temperatures (160°C to 180°C). Vulcanizate properties are good, but high-temperature compression set resistance is mediocre, and retention of physical properties on long exposure to temperatures above 200°C is relatively poor. The chemistry of the diamine cure gives some insight into the problem of embrittlement of seals made of VDF/HFP/TFE fluoroelastomers in longterm exposure at high temperatures to automotive lubricants. Engine oils and transmission lubricants contain large amounts of metal corrosion inhibitors and dispersants that break down to form multifunctional amines. These can react to form enough additional crosslinks to lead to excessive hardness and eventual seal failure. However, actual performance of VDF/HFP/TFE elastomers in automotive oil seals has been excellent, with rare failures under extreme service conditions. The high fluorine content of the terpolymers greatly reduces swelling by oil and incursion of amines, thus minimizing additional crosslinking and giving long service lifetime of the seals.

5.2.2

Bisphenol Cure

Starting in 1970, the bisphenol cure system displaced the diamine system for curing VDF/HFP and VDF/ HFP/TFE fluoroelastomers. This system has the advantages of excellent processing safety, fast cures to high states, excellent final properties, and especially high-temperature compression set resistance in seals. While a number of aromatic dihydroxy compounds can be used as crosslinking agents, including the simplest bisphenol (hydroquinone), the preferred crosslinker is Bisphenol AF, 2,2-bis-(4-hydroxyphenyl)hexafluoropropane, HOΦ–C(CF3)2–ΦOH.[2] An

accelerator such as benzyltriphenylphosphonium chloride,[3] Φ3P+CH2ΦCl– (BTPPC), is necessary, along with inorganic bases, usually calcium hydroxide and magnesium oxide with small particle sizes. A number of other quaternary phosphonium or ammonium salts may also be used as accelerators. A typical VDF/HFP dipolymer compound used for oring seals is as follows: VDF/HFP Dipolymer MT black

100 30

MgO (Maglite D)

3

Ca(OH)2

6

Bisphenol AF

2

BTPPC

0.55

The dipolymer has to be designed to have low ionic end groups[4] to avoid interference with the accelerator, and polymer molecular weight distribution may be adjusted to get the desired rheology for processing.[5] The cure response of this compound is shown in Fig. 5.1,[6] as measured by oscillating disk rheometry (ODR). The torque sensed by the oscillating disk is a measure of the modulus of the compound at the curing temperature of 177°C. For this system, no cure occurs for more than 30 minutes at a processing temperature of 121°C, and a delay of some 2.5 minutes, sufficient to allow mold flow, is observed at the cure temperature of 177°C. Rapid crosslinking then occurs, so that a high cure state is reached within about 5 minutes. Bisphenol and accelerator levels can be adjusted to vary cure rates and states for various applications and processing methods, while retaining the general shape of the cure curve. Crosslink density is proportional to Bisphenol AF level in the range 0.5 to 4 phr (parts per hundred parts of polymer).[7] Curing and properties are shown in Table 5.1 for a VDF/HFP copolymer product[8] offered for compression or injection molding of o-rings, extruded shapes, and calendared sheet. This material is typical of available commercial products, mostly precompounds containing bisphenol and accelerator, offered by the major fluoroelastomer suppliers. The polymer has viscosity, molecular weight distribution, and end groups adjusted for excellent rheology in mold flow and extrusion with low die swell. The polymer is precompounded with curatives to assure the good dispersion necessary for reproducible cure response. Curative levels are not disclosed,

5 CURE SYSTEMS FOR FLUOROELASTOMERS but the precompound probably contains about 2 phr Bisphenol AF crosslinker and 0.5 phr BTPP+ accelerator (as a salt with the bisphenol, no chloride present) to get the high state of cure and moderately high cure rate required for this application. The precompound, VITON® A-401C, has medium viscosity, ML-10 (121°C) = 42. The compound shown meets major specifications for fluoroelastomer o-rings, including original stress-strain properties, retention of properties after aging at 275°C, low swell in fuel and lubricating fluid, and resistance to compression set at 200°C. The heat aging data are consistent with very long service life of bisphenol-cured fluoroelastomers, >3,000 hours at 232°C (450°F) and >1000 hours at 260°C (500°F). The modest decrease in tensile strength and increase in elongation at break indicate some network breakdown at 275°C. The mechanism of bisphenol curing has been elucidated by W. W. Schmiegel in a series of studies of the reactions of various VDF copolymers with a hydroxylic base, amines, and phenols in a solution, using 19F nuclear magnetic resonance (NMR) measurements to determine structural changes in the polymers.[9][10] Figure 5.2[10] shows NMR spectra of a VDF/HFP copolymer before and after treatment with a hydroxylic base in dimethylacetamide, CH3–C(:O)–N–(CH3)2,

79 (DMAC) solution. Schmiegel[10] interpreted these changes as involving the highly selective dehydrofluorination of isolated VDF units, in the chain sequence -HFP-VDF-HFP-, with eventual formation of a diene structure, as shown in Fig. 5.3. The concentration of isolated VDF units can be estimated using the monomer sequencing relationships in Sec. 4.5.3. For a VDF/HFP dipolymer containing 60 wt% VDF, the mole ratio VDF/ HFP is Y = 3.52 and the probability of VDF addition to a VDF radical end is P11 = (Y – 1)/Y = 0.716. From Eq. (4.58), the fraction Q1 of VDF sequences two or more units in length (a = 2) is 2P11 – P112 = 0.92, so the fraction of VDF in isolated units is 1 – Q1 = 0.08, equivalent to about 0.75 moles VDF in -HFP-VDF-HFP- sequences per kg polymer. In the reaction scheme shown in Fig. 5.3, attack by hydroxide results in a double bond formed by abstraction of the tertiary fluorine of HFP and the adjacent acidic hydrogen of VDF. Fluoride ion initiates rearrangement of the double bond, and the resulting allylic hydrogen is abstracted by fluoride, a relatively strong base in the dipolar aprotic DMAC solvent. The reaction sequence results in formation of bifluoride and a conjugated diene structure in the chain.

Figure 5.1 ODR – Bisphenol cure.[6] Cure response by oscillating disk rheometry (ODR) at 177°C of a compound optimized for use in o-rings. The maximum cure rate is the initial slope of the curve: ts2, the time to initiation (increase of the torque by two points from the minimum); tc90 is the time for 90% completion of the cure; and ML, the degree of the state of the cure. The recipe consists of 100 parts polymer, 30 parts MT Black, 6 parts calcium hydroxide, 3 parts magnesium oxide, 0.55 parts of benzyltriphenylphosphonium chloride (BTPPC), and 2 parts of Bisphenol AF.

80

FLUOROELASTOMERS HANDBOOK

Table 5.1 Performance of Bisphenol-Cured VDF/HFP Dipolymer[8]

Compound, phr VITON® A-401C precompound

100

Magnesium oxide (Maglite D)

3

Calcium hydroxide

6

MT Black (N990)

0

Cure, ODR at 177ºC, Microdie, 3º arc ML, in-lb

15

MH, in-lb

122

ts2, minutes

1.7

tc90, minutes

3.2

Vulcanizate Properties, Stress/Strain at 23ºC Press cured 10 minutes at 177ºC M100, MPa

4.6

TB, MPa

9.9

EB, %

57

Hardness, Durometer A

74 After heat aging 70 hours in air at:

Post cured 24 hours at 232ºC

Original

M100, MPa TB, MPa EB, % Hardness, Durometer A

200ºC

232ºC

6.4

6.9

7.2

13.4

14.0

14.0

275ºC

10.3

199

198

177

240

75

78

80

75

Compression set, %, Method B, 25×3.5-mm o-rings 70 hours at 200ºC

15

336 hours at 200ºC

29

70 hours at 232ºC

37

5 CURE SYSTEMS FOR FLUOROELASTOMERS

81

Figure 5.2 NMR of dipolymer before and after base treatment.[10] NMR spectra (94.1 MHz 19F) of VF2 /HFP polymer before (top) and after (bottom) treatment with hydroxylic base in DMAC solution at 20°C (2,5dichlorobenzotrifluoride internal standard). Arrows indicate changes in peak intensities.

Figure 5.3 Reaction of dipolymer and base.[10]

82 Schmiegel made further NMR measurements on VDF/HFP dipolymer treated with a cyclic amidine base and Bisphenol AF or its monofunctional analog to demonstrate the formation of the diene sequence shown in Fig. 5.3, and subsequent nucleophilic substitution of the phenol. NMR measurements were also made on a solvent-swollen pseudovulcanizate of a low molecular weight fluid dipolymer compounded with Bisphenol AF, BTPPC, MgO, and Ca(OH)2. From these studies, Schmiegel concluded that, in practical curing situations, a bisphenol-derived phenolate attacks the diene structure in the polymer, leading to dienic phenyl ether crosslinks, as shown in Fig. 5.4. When a phosphonium salt such as BTPPC is used as accelerator, the phosphonium ion is believed to undergo several cycles of conversion from fluoride (or bifluoride), to hydroxide, to phenoxide, to fluoride, before exhaustion of the phenol. Ultimately, the benzyltriphenylphosphonium ion is converted to triphenylphosphine oxide, which is probably removed during the oven post cure. For the oring compound described previously, the Bisphenol

Figure 5.4 Bisphenol crosslinking scheme.[10]

FLUOROELASTOMERS HANDBOOK AF crosslinker level of 2 phr corresponds to about 60 mmol/kg polymer and the BTPPC accelerator level of 0.55 phr is considerably lower at about 14 mmol/kg polymer. Thus, a number of accelerator reaction cycles are necessary to utilize the bisphenol functionality. This level of bisphenol gives about 120 mmol linkages per kg polymer, corresponding to an average segment molecular weight between links of about 8300 Daltons, or 100 mer units. For low to medium viscosity polymers with number average molecular weights in the range 80,000 to 100,000 Daltons, this relatively high crosslink density corresponds to about 10 to 12 links per chain. It should be noted that the total concentration of reactive -HFP-VDF-HFP- sequences in commercial dipolymer is far higher than that needed for curing. Schmiegel[10] found that, in the absence of free bisphenol, hydroxide attack on the diene structure could form a dienone, as shown in Fig. 5.5. This structure would be susceptible to further hydrolysis and chain cleavage. Commercial bisphenol vulcanizates contain excess calcium hydroxide, so exposure to hot water or steam can lead to eventual network breakdown. VDF/HFP/TFE fluoroelastomers with high fluorine content and greater fluid resistance than the VDF/HFP copolymers discussed above generally give slower cures. Schmiegel[10] studied reactivities in solution of such terpolymers and of several VDF/TFE thermoplastic compositions made by the author. He found that all sequences of single VDF units isolated between perfluorinated monomer units could be dehydrofluorinated readily, but ease of nucleophilic attack on the resulting unsaturated structures varied considerably. Unsaturated structures from sequences -TFE-VDF-TFE- and -TFE-VDF-HFPhad low reactivity toward nucleophiles, and thus, gave little crosslinking by bisphenols. Diene structures from -HFP-VDF-HFP- and -HFP-VDF-TFE- were readily attacked by nucleophiles and crosslinked by bisphenols. Rates of gelation by Bisphenol AF and a cyclic amidine base in DMAC solution were higher for VDF/HFP/TFE (61/17/22 mole %) terpolymer than for VDF/HFP (78/22 mole %) dipolymer. Thus, the slower terpolymer cures in practical bulk systems appear to be caused by the more highly fluorinated medium. The

5 CURE SYSTEMS FOR FLUOROELASTOMERS

Figure 5.5 Hydroxide attack on diene.[10]

terpolymer is less polar, so it is less able to support the ionic intermediates formed during curing. Also the solubility and mobility of curatives are lower in high-fluorine terpolymers. A number of accelerators have been developed for bisphenol curing as alternatives to phosphonium salts such as BTPPC. Patent cross-licensing between DuPont and 3M initially excluded Daikin and Montedison from using the preferred phosphonium accelerators. Daikin developed various bases containing nitrogen heterocyclic structures, including cyclic amidines such as 8-benzyl-1,8-diazabicyclo[5,4,0]-7-undecenium chloride. Montedison developed accelerators based on amino phosphinic derivatives[11] and bis(triarylphosphin)iminium salts.[12] Most of these accelerators were included with bisphenol as ingredients in proprietary fluoroelastomer precompounds offered commercially; exact compositions are generally not disclosed by suppliers. As noted for the DuPont compound described in Table 5.1, a useful variant of a phosphonium accelerator is its bisphenolate salt, thus eliminating the halide anion that could cause demolding problems. Quaternary ammonium salts are also effective accelerators for bisphenol cures. In particular, Schmiegel and Carlson[13] found that tetrabutylammonium hydrogen sulfate (TBAHS) gives fast cures of high-fluorine VDF/HFP/TFE terpolymers to high states with good scorch resistance. A major advantage is that compounds with TBAHS accelerator give much less mold fouling than compounds

83 with accelerators containing chloride, bromide, or iodide anions. In addition to hydrogen sulfate, other anions associated with tetrabutylammonium ion give little or no mold fouling, including fluoride, dihydrogen phosphate, acetate, methane sulfonate, toluene sulfonate, periodate, and bisphenolate. TBAHS was also shown in patent examples to work well with bisphenols other than Bisphenol AF. TBAHS and BTPPC are compared in terpolymer compounds in patent examples from Ref. 13, summarized in Table 5.2. The terpolymers have composition VDF/HFP/ TFE = 45/30/25 wt % (68.5% F) and 35/35/30 wt % (70% F), and were compounded with 30 phr MT black, 4.5 phr calcium hydroxide, and 3 phr high activity magnesium oxide, and curatives as listed in Table 5.2. Compared to BTPPC in these high-fluorine terpolymers, TBAHS gives lower compound viscosity, faster cures to higher states, better compression set resistance, and much less fouling in compression molding tests carried out for fifty molding cycles.

5.2.3

Peroxide Cure

Fluoroelastomers cured with peroxides, or free radicals, exhibit improved resistance to steam, hot water, and aqueous acids over those cured with bisphenols. Peroxide-cured compounds generally do not contain much unsaturation and inorganic bases, so they are less susceptible to attack by aqueous fluids. On the other hand, the crosslinking agents (“radical traps”) used give lower thermal stability than bisphenols. For peroxide curing, fluoroelastomers must contain sites reactive toward free radicals, usually bromine or iodine introduced within chains by incorporation of cure-site monomers or at chain ends by chain-transfer agents. In the late 1970s, DuPont offered the first commercial peroxide-curable fluoroelastomers, containing about 0.5%–0.9% bromine in cure-site monomers such as 4-bromo3,3,4,4-tetrafluorobutene (BTFB).[14] Conditions in the continuous emulsion polymerization process used can be adjusted to minimize unwanted transfer to incorporated bromine-containing units, thus avoiding excessive long-chain branching. Such transfer and branching reactions are more difficult to minimize in semibatch processes, since all the polymer formed remains in the reactor exposed to free radical activity until the end of the batch polymerization. Daikin later developed the semibatch “living radical” iodine

84

FLUOROELASTOMERS HANDBOOK

Table 5.2 Comparison of Accelerators in Bisphenol Cures of VDF/HFP/TFE Terpolymer Compounds[13]

Elastomer

Terpolymer, 68.5% F

Patent Example

Terpolymer, 70% F

4

3

Comparative 2

5

Comparative 3

Bisphenol AF

1.90

1.90

1.9

2.00

2.3

TBAHS

0.67

1.00

Curatives, phr

BTPPC

0.86 1.00

1.03

Mooney Scorch, 121°C Minimum torque

54

49

72

48

62

Minutes to 1-point rise

15

>30

>30

>30

8

Oscillating disk rhometer, ASTM D-2084, 177°C MH-ML, N·m

5.3

4.7

4.6

3.9

3.8

ts0.2, minutes

2.9

2.8

2.5

4.5

4.2

tc90, minutes

4.3

3.8

4.2

6.7

8.9

Stress/Strain, 23°C After press cure (10 min/177°C) M100, MPa

5.1

4.7

4.0

4.2

4.4

TB, MPa

12.1

11.3

10.2

11.3

10.0

EB, %

225

230

280

280

320

M100, MPa

7.0

6.7

6.1

5.4

5.7

TB, MPa

15.2

14.7

13.3

14.4

14.8

EB, %

170

180

187

210

255

After post cre (24 h/232°C)

After heat aging (70 h/275°C) M100, MPa

3.7

4.0

3.7

3.0

3.5

TB, MPa

11.2

10.4

10.4

8.9

7.2

EB, %

245

240

280

345

430

23

30

28

38

50

None

None

Heavy

None

Heavy

Compression Set, ASTM D-395-61, Method B, %, 70 h/200ºC Deposits in mold after 50 cycles

5 CURE SYSTEMS FOR FLUOROELASTOMERS

85 cyanurate (TMAIC), and triallyl cyanurate (TAC) are shown in Fig. 5.6. With its hindered allyl groups, the alternative trap TMAIC does not homopolymerize like TAIC, thus it gives slower cures. TAC gives good cure rates and states, but lower thermal stability than vulcanizates crosslinked with TAIC or TMAIC. Small amounts of metal oxides are useful for absorbing traces of hydrogen fluoride that may be generated during curing. For curing a fluoroelastomer containing about 0.7% bromine incorporated through a cure-site monomer such BTFB, a typical recipe might be:

transfer process to make peroxide-curable polymers with very narrow molecular weight distribution and iodine incorporated on most chain ends.[15] Using multifunctional radical traps to link chain ends results in uniform networks that give low compression set. Thermal resistance of such chain end-linked networks is limited, since loss of relatively few linkages results in formation of many loose long chain segments that do not contribute to elastic recovery, so that physical properties deteriorate considerably. More recently, fluoroelastomers have been made with iodine end groups and bromine- or iodine-containing cure-site monomers to get higher functionality per chain.[16] In a study of peroxide curing of bromine-containing fluoroelastomers,[17] DuPont workers obtained satisfactory cures with aliphatic peroxides 2,5dimethyl-2,5-di-t-butylperoxyhexane, and 2,5-dimethyl-2,5-di-t-butylperoxyhex-3-yne, available from Atochem as Luperco 101XL and 130XL (45% active ingredient on inert support). These peroxides have a half life of 0.8 and 3.4 minutes at 177°C, respectively. Lower molecular weight aliphatic peroxides such as di-t-butylperoxide were found to be active, but too volatile, being partially lost during compound mixing. Peroxides with aromatic substituents (e.g., dicumyl peroxide), gave variable results, probably because of excessive acid-catalyzed decomposition in the fluoroelastomer matrix. Of the radical traps tested, the most effective crosslinker is triallylisocyanurate (TAIC), as judged by cure state and compression set of vulcanizates. Other effective crosslinkers contain unhindered allyl or vinyl groups attached to N, O, or Si; all are electron-rich groups. Electron-poor traps effective in hydrocarbon elastomers, such as m-phenylene-bis-maleimide, are ineffective in fluoroelastomers. Structures of the effective radical traps TAIC, trimethallyl iso-

Fluoroelastomer

100

MT black (N990)

30

ZnO

3

Peroxide (101XL)

3

TAIC

3

This recipe would give time to 90% cure, for about 3 minutes at a temperature of 177°C. Ordinarily, an oven post cure, say 24 h/232°C, is used to develop optimum properties. The cure state of compounds based on bromine-containing fluoroelastomers increases significantly during post curing. Fluoroelastomers with iodine cure sites cure faster to higher cure states during molding, and do not require long post cures at high temperatures. In the DuPont peroxide curing study[17] cited, cure rate and state as measured by ODR modulus increase were directly proportional to the level of bromine-containing cure-site monomer in the polymer. Compression set of vulcanizates improved with cure-site content, with the effect leveling off above about 20 mmol cure-site/kg polymer. At constant cure-site monomer concentration, cure rate increases with increasing levels of both peroxide and radical trap. Cure rate also increases strongly with N

N

CH2

CR

O

C

C

O

CH 2

N

N

CH2

CH 2

CH 2

CH

CH 2

O

C

C

N CH2

CR

CR

CH 2

C

N

O

R=H R =CH 3

Figure 5.6. Radical traps for peroxide curing of fluoroelastomers.

CH2

C

O

T AlC T M AlC

O

TAC

CH2

CH

CH 2

CH

CH 2

86

FLUOROELASTOMERS HANDBOOK

increasing temperature in the range of 160°C to 204°C, with ODR cure times correlated with peroxide half life (approximately the same relationship for peroxides 101XL and 130XL). The state of cure depends mostly on the radical trap level. The cure state increases with peroxide 101XL only up to about 3 phr. Measurements of volatile materials generated during curing at 190°C give further insight into the various reactions occurring in peroxide curing of fluoroelastomers. The polymer used in the study contained about 56 mmol Br/kg polymer (about 0.45% Br). The recipe used was: Fluoroelastomer

100

MT black (N990)

30

Calcium hydroxide

4

Peroxide (101XL)

4

TAIC

4

The peroxide level corresponds to about 60 mmol/kg polymer. The measured levels of volatile products are listed in Table 5.3. No volatiles were formed from the large 2,5-dimethyl-2,5-oxyhexane radical fragment of the peroxide, but the amount of acetone formed was about 80% of the maximum possible for fragmentation of the primary t-butoxy radicals into acetone and methyl radicals. The sum of the amounts of t-butanol (formed by hydrogen transfer to t-butoxy radicals) and isobutene (formed from dehydration of t-butanol) was about eightfold lower than the amount of acetone evolved. The

Table 5.3 Volatiles Generated in Peroxide Curing[17]

Compound

Amount generated, mmoles/kg polymer

Acetone

94.5

t-Butanol

7.8

Isobutene

3.9

Methyl bromide

1.8

Methane

26.8

Ethane

2.6

Propane + propylene

4.1

Water

166

amounts of methyl bromide and volatile hydrocarbons formed from methyl radicals were low relative to the acetone level. This suggests that most of the methyl radicals react with the allyl groups of the TAIC radical trap to form radical adducts that may propagate with other allyl groups, undergo transfer reactions with bromine groups on polymer chains, or add to polymeric radicals. The TAIC level of 4 phr in the compound tested corresponds to about 480 mmoles of allyl functionality per kg polymer, far in excess of that needed for crosslink formation. The amount of water evolved amounts to about 0.3% on polymer, consistent with levels expected in isolated polymer and calcium hydroxide. Consistent with these results, Fig. 5.7 shows the probable reactions resulting from initiator decomposition in a typical compound. Most of the primary tbutoxy radicals undergo ß-scission to acetone and methyl radicals. A major fraction of the methyl radicals add to allyl functionality of the TAIC coagent to form radical adducts. Only a minor fraction of methyl radicals are involved in transfer reactions with fluoroalkyl bromide sites on polymer chains to form methyl bromide and polymeric radicals. If the radical trap concentration is reduced considerably, the amount of methyl bromide increases by up to a factor of two, still relatively low versus the total amount of methyl radicals produced. Proposed crosslinking reactions are shown in Fig. 5.8. Coagent adduct radicals react with bromine cure sites on polymer chains to form polymer radicals. Allyl groups add to these radicals to form crosslinks. The idealized structure shown for crosslinks in Fig. 5.8 is not likely for TAIC radical trap at usual levels >1 phr in compounds. The main reaction for TAIC is polymerization to form oligomers; attachment to polymer chains is a side reaction. However, TMAIC does not homopolymerize, so the structure shown is more likely for this trap. Stock and vulcanizate properties are shown in Table 5.4 for peroxide curing of VDF/HFP/TFE Viton® types containing bromine cure sites from incorporated monomer.[18] Viton® GBL-900 and GBL200 contain about 68% fluorine; GBL-200 also has iodine end groups. GF contains about 70% fluorine for enhanced fluid resistance. All compounds contain 100 Polymer, 30 MT black (N990), 3 Zinc oxide, 1 Carnauba wax, 0.75 VPA#3 processing aid, 2 TMAIC, and 4 Peroxide (Luperco 101XL). Slabs were press cured 10 min/177°C and post cured 24 h/232°C.

5 CURE SYSTEMS FOR FLUOROELASTOMERS

87

Figure 5.7 Probable reactions from peroxide decomposition.[17]

Figure 5.8 Proposed crosslinking mechanism.[17]

These bromine-containing polymers have fairly good thermal resistance, showing good retention of properties after short-term service at 232°C. Based on approximate bromine and iodine levels, and number average molecular weights, the average chain contains some 4–10 cure sites. Thus, most chains are linked into the network at several points, so degradation of linkages must be extensive to cause significant loss of mechanical properties. Mold sticking and fouling are often encountered in peroxide curing of bromine-containing fluoroelastomers. Processing and release aids are usually included in their compounds to minimize molding problems. Typical peroxide cure properties of a VDF/HFP/ TFE (70% fluorine) terpolymer with iodine end groups are shown in Table 5.5.[19] The polymer is Daikin Dai-el® G-902, which contains an average of about 1.8 iodine ends per chain. Thus chains are tied to the network at no more than two points. Generally, cured products are satisfactory for long-term service up to 200°C. At higher temperatures, thermal breakdown of a relatively small fraction of linkages results in severe loss of mechanical properties. Since the iodine sites are very reactive toward radicals, cures are very fast. Usually TAIC is used for crosslinking, since the allyl groups add readily to fluorinated radicals at chain ends. TMAIC is not satis-

factory for curing these iodine-containing polymers. The hindered methallyl groups add much more slowly to chain radicals, so that other reactions may occur and limit the efficiency of crosslinking. Good mold release is obtained when TAIC is used with iodinecontaining polymers. Good properties are obtained with little or no post cure. Only a press cure of 15– 20 minutes at 170°C was used for the compound shown in Table 5.5, with the recipe: 100 polymer (Dai-el® G-902), 20 MT black, 3 magnesium oxide (low activity grade), 3 peroxide (equivalent to 101XL), and 3 TAIC. Premature curing during processing (scorch) of peroxide compounds can be minimized, if necessary, by addition of small amounts of phenolic or amine free radical inhibitors such as 2,6-di-t-butyl-4methylphenol.[17] Long-chain aliphatic amines may also serve as processing aids. A number of peroxide-curable fluoroelastomers have been developed recently that have iodine on most chain ends and additional iodine in cure-site monomer units incorporated along chains.[20] Such polymers give fast cures to high state, excellent demolding characteristics, excellent compression set resistance, and thermal resistance comparable to that of bromine-containing polymers such as those in Table 5.4.

88

FLUOROELASTOMERS HANDBOOK

Table 5.4 Peroxide Curing of VDF/HFP/TFE Fluoroelastomers Containing Bromine Cure Sites[18]

Polymer: Viton®

GBL 900

GBL 200

GF

86

37

87

44 >30

19 >30

46 >30

21 79 2.2 7.4

10 77 1.6 6.8

18 70 2.3 7.4

5.9 20.0 220 75

4.3 19.1 315 79

7.0 20.6 261 80

5.7 21.1 227 76

4.7 19.2 267 78

7.1 21.2 228 81

8.7 20.7 178 76

8.8 15.9 146 78

8.6 21.1 201 81

17 51 66

18 68 81

18 63 72

5 65 4 3 9

5 65 6 2 9

3 4 6 2 8

–46 –15

–46 –16

<54 4

Stock Properties

Viscosity, ML-10(121ºC) Mooney Scorch, MS (121ºC) Minimum, in lb Time to 2 point rise, minutes ODR at 177ºC, Microdie, 3º arc ML, in-lb MH, in-lb ts2, minutes tc90, minutes Vulcanizate Properties Stress/Strain at 23ºC – Original M100, Mpa TB, Mpa EB, % Hardness, Durometer A Stress/Strain at 23ºC – Aged 168 h/200ºC M100, Mpa TB, Mpa EB, % Hardness, Durometer A Stress/Strain at 23ºC – Aged 70 h/232ºC M100, Mpa TB, Mpa EB, % Hardness, Durometer A Compression Set, Method B, O rings, % 70 h/23ºC 70 h/200ºC 168 h/200ºC Fluid Resistance, Volume Swell, % Fuel C, 168 h/23ºC Methanol, 168 h/23º Conc. Sulfuric Acid, 168 h/70ºC ASTM Oil #3, 168 h/150ºC Water, 168 h/100ºC Low Temperature Properties Brittle Point, ºC Glass Transition Temperature, ºC

5 CURE SYSTEMS FOR FLUOROELASTOMERS

89

Table 5.5 Peroxide Curing of VDF/HFP/TFE Fluoroelastomer Containing Iodine Cure Sites at Chain Ends[19]

Polymer: Dai-el®

G-902

Stock Properties Mooney Scorch, ML at 145ºC Time to 5-point rise, minutes

6.7

JSR Curelastometer, 170ºC tc90, minutes

1.3

Vulcanizate Properties Stress/strain – original, press cured M100, MPa

2.7

TB, MPa

16.9

EB, %

320

Hardness, JIS A

72

Compression set, % 70 h/120ºC

13

265 h/120ºC

16

Stress/strain – after 70 h/40ºC in fuel D

5.3

M100, MPa

2.1

TB, MPa

15.1

EB, %

320

Hardness, JIS A

66

Volume swell, %

5.9

VDF/PMVE/TFE Elastomers: Peroxide (Bisphenol)

When curing of VDF/PMVE/TFE terpolymer is attempted with standard bisphenol or diamine recipes, the result is formation of excessive fissures and porosity in poorly cured molded parts. Base treatment of these polymers generates a large amount of volatiles, with little crosslinking with nucleophiles. In his study of crosslinking of VDF copolymers with nucleophiles, Schmiegel[10] clarified the reactions of bases with VDF/PMVE/TFE polymers in solution, using 19NMR and specific amines to identify the resulting products. Analogous to HFP-containing poly-

mers, the most base-sensitive sites are the adjacent PMVE and VDF units in the sequences -PMVEVDF-PMVE- or -PMVE-VDF-TFE. Base attack results mostly in the removal of the elements of trifluoromethanol, HOCF3, from the chain, rather than HF. Removal of –OCF3 groups gives unsaturated structures that are unreactive toward nucleophile addition, so that little crosslinking occurs with diamines or bisphenols. Trifluoromethanol is unstable, breaking down into HF and carbonyl fluoride, which in turn hydrolyzes to more HF and CO2. Neutralization of HF with MgO or Ca(OH)2 generates additional water. The large amounts of HF, CO2, and H2O volatiles formed in the course of these reactions leads to excessive porosity in undercured vulcanizates. Typical reactions are outlined below (X = F or OCF3):

90

FLUOROELASTOMERS HANDBOOK

is readily dehydrofluorinated to form an unsaturated site,

In early attempts to attain successful bisphenol curing of this family of polymers, HFP was substituted for part of the PMVE. The resulting VDF/ HFP/PMVE/TFE tetrapolymers had to contain more HFP than PMVE to get adequate curing. Unfortunately, the low-temperature characteristics of such tetrapolymers were little better than those of VDF/ HFP/TFE terpolymers with similar VDF content. In the 1970s, DuPont introduced peroxide-curable VDF/PMVE/TFE elastomers with brominecontaining cure-site monomers.[14] Compounding and curing are the same as described in the previous section on peroxide curing of VDF/HFP/TFE fluoroelastomers. Analogous VDF/PMVE/TFE fluoroelastomers with iodine end groups and bromineor iodine-containing cure-site monomers were developed for better processing and curing characteristics. Peroxide-cured vulcanizates have the desired improved low-temperature characteristics and good fluid resistance for which this family of fluoroelastomers was developed. Peroxide cure characteristics and vulcanizate properties are shown in Table 5.6 for two fluid-resistant (67% fluorine) VDF/ PMVE/TFE fluoroelastomers, Viton® GFLT with a bromine-containing cure-site monomer incorporated, and Viton® GFLT-300 with iodine on chain ends in addition to bromine cure sites.[21] The compounds contain 100 polymer, 30 MT black (N990), 3 zinc oxide, 2.5 peroxide (Luperco 101XL), and 2.5 TAIC. Slabs were press cured for 8 minutes at 177°C and post cured for 24 hours at 232°C. Recently, Schmiegel and Bowers[22] developed practical bisphenol cures of VDF/PMVE/TFE fluoroelastomers with a specific cure-site monomer and special compounding. The cure-site monomer, usually incorporated at levels of 1%–3%, is 2-hydropentafluoropropylene (2H-PFP), CF2=CH–CF3. The incorporated monomer unit,

which is highly reactive toward addition of nucleophiles such as bisphenols. Independent of adjacent monomer units, 2H-PFP sites are more reactive than sequences of isolated VDF units flanked by perfluoromonomer units. Other components of the cure recipes are chosen to facilitate crosslinking at 2H-PFP sites while minimizing reactions involving VDF sequences. Preferably, HF generated is absorbed by molecular sieve zeolites, crystalline aluminosilicates, and by metal oxides such as MgO or CaO. Usually, calcium hydroxide is not used, since neutralization with HF would generate water, which would facilitate attack on VDF sites. While thermal black filler can be used, curing is enhanced with a modified silane-coated mineral filler, such as aminosilane-coated wollastonite (calcium metasilicate, CaSiO3). In a patent example, bisphenol curing of a VDF/PMVE/TFE elastomer (labelled 1B) containing 2H-PFP cure-site monomer is compared to peroxide curing of a similar commercial fluoroelastomer (control) with cure-site monomer 4-bromo3,3,4,4,-tetrafluorobutene (BTFB). Polymer characteristics, cure recipes, and properties are shown in Table 5.7. In other curing examples, a polymer similar to 1B was formulated with 2 phr Bisphenol AF and 45 phr of various epoxysilane- or aminosilane-coated wollastonite fillers to get much faster cures (90% cure times near 2 minutes) to somewhat higher states with better compression set resistance. No sponging was observed in these vulcanizates. This development allows application of the bisphenol cure system, with its improved processing characteristics and thermal stability, to be applied to the VDF/PMVE/ TFE family of fluoroelastomers. Resistance of VDF/PMVE/TFE vulcanizates to fluids containing organic amines is better than that of VDF/HFP/TFE vulcanizates because multifunctional amines do not readily add to unsaturated sites in the PMVE-containing polymers. Thus, they do not fail by excessive crosslinking, therefore, they do not cause the surface to crack or cause the embrittlement produced in HFP-containing polymers.

5 CURE SYSTEMS FOR FLUOROELASTOMERS

91

Table 5.6 Peroxide Curing of VDF/PMVE/TFE Fluoroelastomers Containing Bromine Cure Sites[21]

Polymer: Viton®

GFLT

GFLT-300

Minimum, in-lb

47

29

Time to 5-point rise, minutes

>30

28

ML, in-lb

24

17

MH, in-lb

89

101

ts2, minutes

1.1

0.9

tc90, minutes

5.2

4.4

M100, MPa

7.5

7.0

TB, MPa

18.7

17.9

EB, %

180

180

Hardness, durometer A

72

72

M100, MPa

7.2

5.3

TB, MPa

17.9

16.7

EB, %

200

253

33

33

Fuel C, 168 hours at 23ºC

5

4

Methanol, 168 hours at 23ºC

8

6

Glass transition temperature, ºC

-23

-25

Stock Properties Mooney Scorch, MS at 121ºC

ODR at 177ºC, Microdie, 3º arc

Vulcanizate Properties Stress/strain at 23ºC – original

Stress/strain at 23ºC – Aged 70 h/250ºC

Compression set, method B, O-rings, % 70 hours at 200ºC Fluid resistance, volume swell, %

92

FLUOROELASTOMERS HANDBOOK

Table 5.7 Curing of VDF/PMVE/TFE Elastomers with Bisphenol or Peroxide[22]

Polymer Example 1B Control Composition, wt % VDF 54.1 55 PMVE 33.9 34.8 TFE 10.0 10 2H-PFP 2.0 -BTFB -1.2 Viscosity Inherent viscosity (MEK, 30ºC) 1.10 1.3 ML-10 (121ºC) 89 90 Glass transition temperature, ºC -29 -30 Formulation Example 1B Control Polymer 100 100 MT Black (N990) 30 30 Calcium oxide 6 -Calcium hydroxide -5 Molecular sieve 13X 3 -Peroxide 101XL -4 TMAIC -2 TBAHS 0.5 -Bisphenol AF 2.5 -Cure Characteristics Example 1B Control ODR at 180ºC ML, dN·m 7.1 10.3 MH, dN·m 43.9 56.8 ts2, minutes 3.2 1.8 tc50, minutes 7.3 3.7 tc90, minutes 18.0 7.2 Vulcanizate Properties (press cure 15 minutes at180ºC, post cure 24 hours at 232ºC) Stress/strain at 23ºC M100, MPa 5.0 6.1 TB, MPa 15.1 20.1 EB, % 244 212 Hardness (shore A) 71 69 TR-10, ºC -26 -28 Compression set, pellets, % 70 hours at 200ºC 32 26

5 CURE SYSTEMS FOR FLUOROELASTOMERS

5.4

Perfluoroelastomers— Various Systems

DuPont workers developed perfluoroelastomers based on TFE/PMVE copolymers. These polymers are almost as resistant to fluids as polytetrafluoroethylene thermoplastics, and are usable at temperatures up to 315°C (600°F). A major problem in early product development was to find practical cure systems with thermal stability of crosslinks comparable to that of the polymer. The system used for the first commercial products is based on bisphenol curing of perfluoroelastomers containing the cure-site monomer perfluoro(2-phenoxypropyl vinyl ether).[23] The preferred curing system uses the dipotassium salt of Bisphenol AF (K2AF) with a crown ether such as dicyclohexyl-18-crown-6, which coordinates with potassium ion and facilitates transport of ionic species to cure sites.[24] The crosslink formation reaction presumably involves removal of a fluorine from a pendent perfluorophenoxy group and addition of bisphenolate ion at this site to form an ether linkage. To avoid excessive degradative transfer during incorporation of the perfluorovinyl ether cure-site monomer units, polymerization temperatures must be low, typically 65°C to 85°C. Persulfate-sulfite redox initiation systems are used for these polymers, resulting in mostly sulfonate end groups. Ionic clusters of these end groups are stable at temperatures over 200°C, so polymer viscosity is extremely high at processing and molding temperatures. Mixing with fillers (e.g., 10 phr SRF black) and curatives is difficult, as is fabrication of preforms for molding of parts. Little cure occurs in a press at 190°C, so the mold must be cooled before removal of parts to prevent sponging. Curing is completed in a long post cure, some two days at temperatures up to 288°C (550°F) under nitrogen. Because of the great difficulties encountered in processing and curing, DuPont decided to make and sell perfluoroelastomer fabricated parts rather than polymer.[25] Compared to parts from hydrofluoroelastomers, the resulting Kalrez® K1000 series perfluoroelastomer parts have much higher thermal stability: after 20 days at 288°C in air, 100% modulus decreases by <25%, tensile strength decreases by <15%, and elongation at break increases by 120%.[26] In a later development, Finlay found that a small amount of a hydrocarbon-containing monomer such as VDF could be incorporated in TFE/PMVE polymer in place of the high-cost

93 perfluoro(2-phenoxypropyl vinyl ether) to allow bisphenol curing.[27] Improved performance has been achieved with TFE/PMVE perfluoroelastomers containing the cure-site monomer perfluoro(8-cyano-5-methyl-3,6dioxa-1-octene), CF2=CF–O–CF2–CF(CF3)–O– CF2–CF2–CN, 8-CNVE.[28] Tetraphenyltin is used to catalyze formation of highly stable triazine crosslinks, schematically shown in Fig. 5.9.[29] The curing reaction does not require a crown ether solvent. A reasonable state of cure is obtained in the press, so that parts can be removed from a hot mold without sponging. As with the K2AF system, a long oven post cure at high temperature is necessary to develop full properties. It seems likely that the long cure time is necessary to form the triazine crosslink structures, each involving three cyano groups on polymer chains. Thermal stability of the triazine vulcanizates is high. Kalrez ® K4000 series perfluoroelastomer parts are unchanged from original post cured properties after aging 18 days at 288°C in air. They retain useful properties after similar aging at 316°C: 100% modulus decreases by <20%, tensile decreases by <40%, and elongation at break is unchanged.[26] As with VDF-containing fluoroelastomers, bromine-containing monomers may be incorporated in perfluoroelastomers to allow peroxide curing.[14] Iodine end groups may be incorporated by transfer to get faster cures.[30] Daikin applied its “living radical” polymerization technology[15] to obtain perfluoroelastomers with narrow molecular weight distribution and mostly iodine end groups. The perfluoro(alkyl vinyl ether) copolymerized with TFE in Daikin Perfluor® has a relatively long alkyl side chain, probably perfluoro(2-propoxypropyl vinyl ether). Since the iodine-containing perfluoroelastomers have excellent processing characteristics, Daikin elected to sell the gum elastomer to fabricators. Peroxide-cured

Figure 5.9 Crosslinking structure for nitrile perfluoroelastomers.[29]

94

FLUOROELASTOMERS HANDBOOK

perfluoroelastomer vulcanizates are resistant to most fluids, except oxidizing materials, and have outstanding resistance to hot water and steam. Thermal resistance is similar to that of other peroxide-cured fluoroelastomers, adequate for long-term service up to 200°C. Since the bulk of perfluoroelastomer end uses require outstanding fluid resistance, but not resistance to extremely high temperatures, peroxidecured products are satisfactory here. In a 1986 review, Logothetis[31] summarized differences in fluid and thermal resistance of TFE/ PMVE perfluoroelastomer vulcanizates cured with three different cure systems, using three different cure-site monomers. The polymers evaluated had about the same major monomer composition, and the vulcanizates had about the same initial properties after post cure: M100 = 6.5–8.0 MPa, TB = 13–16 MPa, and EB = 140%–160%; Shore A Hardness = 80. Listed in Table 5.8 are changes in tensile strength after heat-aging in air for 10 days at various temperatures and the swell in various fluids after 70hour exposures. Triazine crosslinks from –RfCN cure sites are exceptionally stable to heat-aging in air, being unaffected up to 290°C. At this temperature, tensile strength increases initially, then levels off on further exposure. This vulcanizate has reasonable service

life at temperatures up to 315°C. The hydrocarbon crosslinks of the peroxide-cured polymer with –RfBr cure sites begin to break down significantly at 225°C. The bisphenol-cured polymer is intermediate in heat resistance. Swell of these perfluoroelastomer vulcanizates is low in most fluids. However, as with other fluoroelastomers, bisphenol vulcanizates are susceptible to swell and breakdown in hot aqueous environments, while peroxide cures are resistant. Peroxide-curable perfluoroelastomers with enhanced heat resistance have recently been developed by Ausimont (now Solvay Solexis) workers, using new branching and pseudo-living radical microemulsion polymerization technology.[32] In this semibatch process, a perfluorinated diiodide modifier, I(CF2)6I, is used as described in Sec. 4.6.1 to make a narrow molecular weight distribution polymer with iodine on most chain ends. In addition, a fluorinated diolefin, CH2=CH–(CF2)6–CH=CH2, is incorporated to get significant branching. The resulting polymer has more than two iodine groups per chain and considerable pendant vinyl groups. This perfluoroelastomer, possibly precompounded with additional fluorinated diolefin, can be cured with peroxide only (no added TAIC radical trap) to produce vulcanizates with good long-term stability up to 290°C.[33]

Table 5.8 Heat Aging and Fluid Swell of Perfluoroelastomer Vulcanizates[31]

Cure Site Probable cure site monomer Curative

–RfCN

–H

–RfBr

8-CNVE

VDF

BTFB

Ph4Sn

Bisphenol

TAIC

Heat Aging (% change in TB after aging 10 days in air at temperature ) 225ºC

-3

-11

250ºC

-24

-54

275ºC

-45

-80

290ºC

+24

-36

Fluid Resistance (% swell after 70-hour exposure) Conc. nitric acid, 85ºC

3

8

9

Glacial acetic acid, 100ºC

3

32

16

13

10

14

Methyl ethyl ketone, 70ºC

6

4

4

Toluene, 100ºC

7

7

7

10

60

7

Butyraldehyde, 70ºC

Water, 225ºC

5 CURE SYSTEMS FOR FLUOROELASTOMERS A number of improvements have been reported recently for nitrile-containing perfluoroelastomers. Better processing polymers have been obtained with initiation of polymerization by persulfate thermal decomposition.[34] The resulting carboxyl (-COOH) and carboxylate (-COO-) end groups form ionic clusters that are much less stable than those involving sulfonate ends. In a further improvement, carboxylate end groups can be removed by pyrolysis at 250°C-325°C to get low-viscosity polymers that are readily mixed to obtain compounds with good flow characteristics for extrusion and molding.[35] The cyano cure sites have been found to be quite versatile, allowing curing with certain nitrogen-containing nucleophilic compounds,[36] with ammonium salts of organic or inorganic acids,[37] or with ammonia-generating compounds.[38] Apparently, in most of these cases, stable triazine crosslinks are formed after long high-temperature post cures. Nitrile-containing perfluoroelastomers are also curable with peroxide and radical trap. Ojakaar[39] discloses curing of TFE/PMVE/8-CNVE perfluoroelastomer with α,α´-bis(t-butylperoxy)diisopropylbenzene peroxide, trimethallyl isocyanurate crosslinker, and 1,8-bis(methylamino)naphthalene organic base. Cure rates are much faster than those with tetraphenyltin, and post curing can be carried out at lower temperatures for shorter times. The peroxide-cured perfluoroelastomers have better resistance to hot water and ethylene diamine than that of the same polymers cured with tetraphenyltin. Apparently, hydrocarbon radicals on TMAIC moieties add to –RfCN groups on polymer chains to form stable crosslinks.

5.5

TFE/Propylene Elastomers: Peroxide, Bisphenol

In the 1960s, workers at DuPont[40] and Asahi Glass[41] found that TFE and propylene can be copolymerized in alternating fashion to form fluoroelastomers. Early attempts to cure TFE/P elastomers with various incorporated cure-site monomers did not produce commercially satisfactory vulcanizates. Also, elastomer processors regarded the material as deficient in such properties as compression set resistance, low-temperature flexibility, and resistance

95 to aromatic solvents compared to available VDFcontaining fluoroelastomers. The excellent resistance of TFE/P elastomers to polar solvents and to amines and inorganic bases was not considered to be important enough to offset the deficiencies, so DuPont did not offer the product commercially. However, Asahi Glass continued to develop polymerization and curing systems, introducing TFE/P copolymer as Aflas® in the mid-1970s. Much of the polymer has been used in Japanese wire and cable coating applications because of its excellent electrical properties. Use in elastomer fabricated parts has been relatively low, but increasing recently because of need for base-resistant fluoroelastomers. To minimize transfer reactions to propylene (and small amounts of propane in the monomer), Asahi Glass workers developed a redox initiation system to allow polymerization at low temperature (near 25°C).[42] The initiation system, consisting of ammonium persulfate, ferrous sulfate, ethylene diamine tetraacetic acid (EDTA), and sodium hydroxymethanesulfinate, allows attainment of number average molecular weights above 100,000 Daltons. Sulfate ion radicals are formed from the oxidation of ferrous ion by persulfate in a fast reaction. Ferric ions are in turn reduced back to ferrous ions by hydroxymethanesulfinate in a rate-determining step involving hydroxide ion. EDTA forms complexes with ferric and ferrous ions, so that they do not destabilize the polymer dispersion. Perfluorocarbon surfactants and a buffer system (disodium hydrogen phosphate and sodium hydroxide, to maintain pH in the range 5.5 to 10) are used to stabilize the dispersion. Reactor pressure is maintained at about 2.5 MPa with a monomer mixture rich in TFE to attain reasonable reaction rates. The isolated TFE/P dipolymer is subjected to a heat treatment to generate enough unsaturation to allow peroxide curing.[43] The Asahi Glass heat treatment is carried out in the presence of air at temperatures high enough to start polymer degradation, typically 300°C to 360°C for 2 to 4 hours. Time and temperature are chosen to get significant modification without excessive reduction of molecular weight. Besides allowing curing, the unsaturation and carbonyl groups formed enhance adhesion of the elastomer to substrates such as metal and cloth. The efficiency of the heat treatment may be enhanced by addition of a metal oxide such as magnesium oxide. In a patent example, a copolymer with compo-

96 sition TFE/P = 55/45 mole % and number average molecular weight 180,000 Daltons was mixed with 0.5 phr MgO and heated at 300°C for 2 hours in air in an electric oven to obtain the modified fluoroelastomer. This was compounded with 5 phr a,a´-bis(tbutylperoxy)-p-diisopropyl benzene, 3 phr triallyl isocyanurate, and 25 phr MT carbon black. After a press cure of 30 minutes at 160°C and oven post cure of 1 hour at 160°C, 1 hour at 180°C, and 2 hours at 200°C, the following vulcanizate physical properties were obtained: M100 = 3.1 MPa, TB = 18.1 MPa, EB = 260%, hardness (JIS-A) = 70, and compression set = 22% after 22 hours at 200°C. Typical properties of a heat-treated TFE/P dipolymer cured with peroxide and radical trap are listed in Table 5.9.[44] The compound was press cured 30 minutes at 160°C and post cured 2 hours at 200°C. Compared to VDF/HFP/TFE fluoroelastomers, TFE/P dipolymer vulcanizates have poorer lowtemperature characteristics and resistance to compression set. With their lower fluorine content (55%–57%), TFE/P vulcanizates exhibit high swell in hydrocarbons, especially mixtures containing aromatics, but are resistant to aqueous fluids and polar solvents. To obtain higher fluorine content and better curing characteristics, terpolymers of TFE and propylene with VDF have been made. During the early 1970s, DuPont workers made terpolymers containing 5–26 mole % VDF, 50–65 mole % TFE, and 20– 45 mole % P that were curable with diamine carbamate crosslinkers and quaternary ammonium or phosphonium accelerators.[45] In later work at Asahi Glass, aqueous dispersions of terpolymers containing 25–35 mole % VDF, about 40 mole % TFE, and 25–35 mole % P were treated with sodium hydroxide before isolation of the polymer, to generate double bonds used for curing with peroxide and radical trap,[46] or with bisphenol and quaternary ammonium or phosphonium salts.[47] Further improvements in bisphenol curing of TFE/P/VDF terpolymers were made at 3M by Grootaert and Kolb,[48] who found more effective accelerators for polymers containing high levels of VDF. The preferred polymer composition is in the range 30–36 mole % VDF, 41–45 mole % TFE, and 19–28 mole % P (thus about 58%– 60% fluorine), cured with Bisphenol AF and tributyl(2-methoxy)propyl phosphonium chloride. Vulcanizate properties of a precommercial version

FLUOROELASTOMERS HANDBOOK were described at a 1989 ACS Rubber Division meeting.[49] Resistance to automotive motor oils was compared to that of bisphenol-cured VDF/HFP dipolymer and peroxide-cured VDF/HFP/TFE terpolymer; representative results are shown in Table 5.10. All polymers were compounded with 30 phr MT black filler and press cured 12 minutes at 177°C. The bisphenol compounds were post cured at 230°C, the peroxide compound at 200°C for 16 hours. Both VDF/HFP/(TFE) vulcanizates had surface cracks after this oil exposure. The bisphenol-cured TFE/P/VDF elastomer shows significantly better resistance to lubricating oils than that of VDF/HFPcontaining elastomers. In a later review of the commercial 3M product, Fluorel® II, Hull[50] recommends the bisphenol-cured TFE/P/VDF terpolymer for service in automotive engine oils, transmission fluids, and gear lubricants, but not for aqueous environments. A peroxide-cured terpolymer is recommended for service in engine coolants. These VDFcontaining terpolymers have better processing and curing characteristics than TFE/P dipolymers, but base resistance is significantly compromised by the presence of the large fraction of VDF units. Base resistance of TFE/P/VDF vulcanizates is generally similar to that of VDF/PMVE/TFE elastomers, which have better low-temperature characteristics. In the late 1990s, workers at DuPont Dow Elastomers re-investigated the TFE/P elastomer family to develop fully base-resistant products with better processing and curing characteristics. Terpolymers of TFE and propylene with small amounts of certain cure-site monomers allowing practical bisphenol cures have been developed. [51] A preferred version is a terpolymer containing 73 wt % TFE, 23 wt % P, and 4 wt % trifluoropropylene (TFP), CF3–CH=CH2. TFP is incorporated as isolated units flanked by TFE units. Dehydrofluorination results in –CF2–CF2–CH2–C(CF3)=CF–CF2– structures to which nucleophiles can attach to form crosslinks. Highly reactive accelerators are desirable to get good cure rates. A preferred compound includes as the curative/accelerator combination methyltributylammonium Bisphenol AF salt (1:1 molar ratio) along with calcium hydroxide, active magnesium oxide, and fillers. This product has much better base resistance than VDF-containing terpolymers, and better hydrocarbon fluid resistance than TFE/P dipolymers because of its higher fluorine content (58%).[52]

5 CURE SYSTEMS FOR FLUOROELASTOMERS

97

Table 5.9 Properties of TFE/P Dipolymer Vulcanizate[44]

Heat-Treated Polymer Specific gravity Mooney viscosity, ML-10 (100ºC) Appearance

1.55 85 Dark Brown

Formulation, phr Polymer

100

á,á´-bis(t-butylperoxy)-p-diisopropyl benzene

2

Triallylisocyanurate

3

MT carbon black (N-908)

30

Vulcanizate Properties Specific gravity

1.60

Stress/strain at 25ºC M100, MPa

3

TB, MPa

20

EB, %

300

Compression set at 200ºC, % After 1 day

40

After 30 days

65

Hardness, Durometer A

72

Low-temperature characteristics Brittle Point, ºC Retraction temperature, TR-10, ºC

-40 3

Volume increase after fluid immersion, % 95% Sulfuric acid, 3 days at 100ºC

4.4

Water, 3 days at 150ºC

8.7

Steam, 3 days at 160ºC

4.6

Fuel Oil B, 7 days at 25ºC

59

Benzene, 7 days at 25ºC

40

Methanol, 7 days at 25ºC

0.2

Ethyl acetate, 7 days at 25ºC

88

98

FLUOROELASTOMERS HANDBOOK

Table 5.10 Comparison of TFE/P/VDF with VDF/HFP/(TFE) Elastomers[49]

Polymer

VDF/HFP

VDF/HFP/TFE/Br-CSM

TFE/P/VDF

% Fluorine

66

70

59

Cure system

BpAF

Peroxide

BpAF

ML, N·m

1.0

3.3

1.1

MH, N·m

7.9

11.3

8.9

ts0.2, minutes

1.7

1.1

2.7

tc90, minutes

4.0

5.9

5.8

M100, MPa

3.6

5.3

5.1

TB, MPa

13.7

14.3

15.2

EB, %

286

219

235

75

76

74

ODR at 177ºC

Stress/strain

Hardness, Shore A

% Change in properties after exposure to 10W/30 SG/CC motor oil, 168 h at 160ºC M100

+29

+31

+9

TB

-63

-32

-38

EB

-59

-40

-17

In a recent update to his previous studies (discussed in Secs. 5.1.2 and 5.2, Refs. 9 and 10), Schmiegel[53] used high-resolution 377 MHz 19F NMR to study the reactions of TFE/P copolymers with the organic base DBU in solution. Treatment of terpolymer with TFE/P/VDF = 54/14/32 wt % = 39/24/37 mole % in deuterated tetrahydrofuran solution with excess DBU gives considerable reaction at VDF sites with elimination of HF, as shown in Fig. 5.10, similar to reactions observed with VDF/ TFE dipolymers in the previous study. Only part of these reactions is at TFE/VDF/TFE sites that may be usable in curing. Thus, the NMR study is consistent with the need to incorporate high VDF levels (>10%) to get acceptable curing. VDF is relatively

inefficient as a cure-site monomer in TFE/P copolymers. The remaining unsaturation formed by base attack is not susceptible to nucleophilic addition, so vulcanizates do not fail by surface cracking or embrittlement. However, such unsaturation is susceptible to hydrolysis and network breakdown, especially in hot aqueous environments. In contrast, TFE/P/TFP terpolymers show attack by DBU only at the TFP site, with little HF evolution, as shown in Fig. 5.11. The bulk of the polymer shows no change, as shown in Fig. 5.12. Thus this cure-site monomer allows curing without base attack on the bulk of the main chain of the terpolymer. The deleterious effect of increasing VDF content on oil resistance of TFE/ P copolymers is shown in Fig. 5.13.

5 CURE SYSTEMS FOR FLUOROELASTOMERS

Figure 5.10 DBU Treatment of TFE/P/VDF Terpolymer[53]

99

Figure 5.13 Base resistance of TFE/P/VDF elastomers.[53] Effect of weight % content of vinylidene fluoride on polymer base resistance: Change in Eb after aging in ASTM Reference Oil 105 @ 150°C.

5.6

Figure 5.11 Attack of DBU on TFP Site[53]

Figure 5.12 Treatment of TFE/P/TFP Terpolymer[53]

Ethylene/TFE/PMVE Elastomers: Peroxide, Bisphenol

Ethylene/TFE/PMVE (ETP) elastomers were developed during the early 1980s for severe service in oil field, aerospace, and automotive applications.[54] ETP was designed to have better resistance to polar fluids and base than that of VDF/HFP/TFE and VDF/PMVE/TFE elastomers, and better low-temperature flexibility and resistance to hydrocarbons than that of TFE/P elastomers. A bromine-containing cure-site monomer (BTFB) is incorporated in commercial ETP polymers to allow peroxide curing with TMAIC or TAIC radical trap. Patent examples[55] of polymers that appear to approximate commercial offerings have composition in the range E/TFE/PMVE/BTFB = 7.8-6.7/43.6–47.4/46.9– 44.0/1.7–1.9 wt % = 27.7–24.1/43.3–48.1/28.2–26.9/ 0.8–0.9 mole %. This composition contains about 66% fluorine and 1% hydrogen, similar to that of commercial high-fluorine VDF/TFE/PMVE/BTFB types like Viton® GFLT (see Sec. 5.3 and Table 5.6). Compounding, processing, and curing recommendations for the commercial products, Viton Extreme ETP-500 and ETP-900, are given in a recent ACS paper,[56] along with property comparisons with other fluoroelastomers. Compounding is generally similar to that for VDF-containing polymers like GFLT, with some adjustments necessary for service

100

FLUOROELASTOMERS HANDBOOK

in aggressive fluids. TAIC (1 to 4 phr) and TMAIC (0.7 to 3 phr) are recommended as radical traps. TMAIC may give somewhat better compression set and heat aging characteristics. Luperco 101XL or 130XL are satisfactory peroxides. Litharge (PbO) or zinc oxide gives good fluid and heat resistance. MT black is the filler of choice. Other carbon blacks may be used, but furnace blacks may interfere with peroxide curing and cause mold sticking. Mineral fillers such as Blanc Fixe (BaSO4) may be used; other mineral fillers may not be compatible with service in aggressive fluids such as aqueous base. Heat resistance of ETP vulcanizates is generally similar to that of other peroxide-cured fluoroelastomers, with long-term service possible at temperatures up to 230°C. ETP is compared to other fluoroelastomers in compounds with 30 phr MT black (N990), cured to give medium hardness vulcanizates with good physical strength and elongation. Molded slabs were cut into dumbbells for testing in various fluids. Results are shown in Table 5.11 as changes in tensile strength and volume from original properties after immersion for 168 hours.

These results show the good resistance of ETP vulcanizates to a wide range of fluids, including amine-containing lubricants and aqueous that degrade VDF/HFP elastomers, polar solvents which swell VDF/HFP elastomers excessively, and aromatic solvents that severely swell TFE/P elastomer. Recently, Schmiegel and Tang[57] have incorporated low levels of trifluoropropylene (TFP), CF3– CH=CH2, or 2H-pentafluoropropylene (2H-PFP), CF2=CH–CF3, into ETP elastomers to allow bisphenol curing. Effective curing is obtained with Bisphenol AF and tetrabutylammonium hydrogen sulfate or with methyltributylammonium Bisphenol AF salt (1:1 molar ratio). Calcium hydroxide and magnesium oxide are used to take up water and HF generated. Press cure and post cure conditions are similar to those used for other bisphenol-cured fluoroelastomers. The resulting bisphenol vulcanizates have better compression set resistance than that of peroxide vulcanizates of bromine-containing polymers, and retain the excellent fluid resistance of ETP.

Table 5.11 Fluid Resistance of ETP and Other Fluoroelastomers[56]

Fluoroelastomer

A401C

GF

100H

ETP-500

VDF/HFP

VDF/HFP/TFE

TFE/P

E/TFE/PMVE

66

70

57

67

Bisphenol

TAIC

TAIC

TAIC

-37

-53

-8

-6

1

3

6

2

% TB change

-40

-27

-65

-21

% Volume swell

23

11

64

9

% TB change

-91

-86

-66

-34

% Volume swell

222

183

77

19

-95

-92

+12

-8

132*

12*

1

6

Composition % Fluorine Cure

Property change after fluid exposure, 168 h 80W/90 EP gear lube, 150ºC % TB change % Volume swell Toluene, 40ºC

Methyl ethyl ketone, 23ºC

30% Potassium hydroxide, 100ºC % TB change % Volume swell *Sample disintegrating

5 CURE SYSTEMS FOR FLUOROELASTOMERS

101

REFERENCES 1. Arnold, R. G., Barney, A. L., and Thompson, D. C, Rubber Chemistry and Technology, 46:631 (Jul 1973) 2 Moran, A. L., and Pattison, D. B., Rubber World, 103:37 (1971) 3. Pattison, D. B., US Patent 3,876,654, assigned to DuPont Co. (1975) 4. Gladding, E. K., and Nyce, J. L., US Patent 3,707,529, assigned to DuPont Co. (Dec 26, 1972) 5. Moore, A. L., US Patent 3,839,305, assigned to DuPont Co. (Oct 1, 1974) 6. Logothetis, A. L., “Fluoroelastomers,” Organofluorine Chemistry: Principles and Commercial Applications (R. E. Banks, et al., eds.), p. 381, Plenum Press, New York (1994) 7. Fogiel, A. W., Polymer Symposium, J. Polymer Science 53:333 (1975) 8. DuPont Product Information Bulletin VT-220.A401C (Nov, 1992) 9. Schmiegel, W. W., Kautschuk Gummi Kunstoffe, 31:137 (1978) 10. Schmiegel, W. W., Die Angewandte Makromolekulare Chemie, 76/77:39–65 (1979) 11. Moggi, G. and Mancini, L., US Patent 4,259,463, assigned to Montedison S.p.a. (Mar 31, 1981) 12. Moggi, G., US Patent 4,501,858, assigned to Montedison S.p.a. (Feb 26, 1985) 13. Carlson, D. P., and Schmiegel, W. W., US Patent 4,957,975, assigned to DuPont Co. (Sep 18, 1990) 14. D. Apotheker and P. J. Krusic, US Patent 4,035,565, assigned to DuPont Co. (Jul 12, 1977) 15. Tatemoto, M., and Morita, S., US Patent 4,361,678, assigned to Daikin Kogyo Co. (Nov 30, 1982) 16. Moore, A. L., US Patent 4,973,633, assigned to DuPont Co. (Nov 27, 1990) 17. Apotheker, D., Finlay, J. B., Krusic, P. J., and Logothetis, A. L., Rubber Chemistry and Technology, 55:1004–1018 (Sep-Oct, 1982) 18. DuPont Product Information Bulletin VT-240.GBL-900 (May 1993) 19. Okumoto,T., Ichikawa, M., and Terashima, K., Nippon Gomu Kyokaishi, 4:248 (1985); translation in International Polymer Science and Technology, 12(8):65 (1985) 20. Bowers, S., “A New Series of Peroxide Curable Specialty Fluoroelastomers with Significant Improvements in Processability and Physical Properties,” paper given at Brazilian Rubber Congress, Sao Paulo, Brazil (Nov 6–7, 2001) 21. DuPont Product Information Bulletin VT-250.GFLT-300/301 (May, 1993) 22. Bowers, S., and Schmiegel, W. W., US Patent 6,329,469, assigned to DuPont Dow Elastomers LLC (Dec 11, 2001) 23. Pattison, D. B., US Patent 3,467,638, assigned to DuPont Co. (Sep 16, 1969) 24. Barney, A. L., and Honsberg, W., US Patent 3,580,889, assigned to DuPont Co. (May 25, 1971) 25. Schroeder, H. E., Rubber Chemistry and Technology 57:G100 (Jul–Aug 1984) 26. Carlson, D. P., and Schmiegel, W. W., “Fluoropolymers, Organic,” in: Ullmann’s Encyclopedia of Industrial Chemistry, Fifth Edition, A11:424, VCH Verlagsgesellschaft mbH, Weinheim, Germany (1988) 27. Finlay, J. B., US Patent 4,529,784, assigned to DuPont Co. (Jul 16, 1985) 28. Breazeale, A. F., US Patent 4,281,092, assigned to DuPont Co. (Jul 28, 1981) 29. Logothetis, A. L., “Novel Perfluoroelastomers,” paper given at Centenary of the Discovery of Fluorine International Symposium, Paris, France (Aug 25–29, 1986) 30. Logothetis, A. L., US Patent 4,948,853, assigned to DuPont Co. (Aug 14, 1990)

102

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31. Logothetis, A. L., “Novel Fluoroelastomers,” paper presented at International Fluorine Symposium, Paris, France (Aug 25–29, 1986) 32. Ferro, R., Arcella, V., Albano, M., Apostolo, M. and Wlassics, I , “New Developments in Polymerization Technologies and Curing,” paper presented at International Rubber Conference, Manchester, UK (Jun 1999) 33. Anonymous, Tecnoflon PFR 95 Solvay Solexis Product Data Sheet (Dec 2002) 34. Coughlin, M. C., and Manaco, C. D., US Patent 5,789,489, assigned to DuPont Dow Elastomers LLC (Aug 4, 1998) 35. Schmiegel, W. W., US Patent 5,789,509, assigned to DuPont Dow Elastomers LLC (Aug 4, 1998) 36. C. J. Bish, P. A. Morken, and W. W. Schmiegel, US Patent Application Publication No. US 2002/ 0026014 (Feb 28, 2002) 37. Kumiya, F., Saito, S., and Tatsu, H., US Patent 5,565,512, assigned to Nippon Mektron, Limited (Oct 15, 1996) 38. MacLachlan, J. D., Morken, P. A., Schmiegel, W. W., and Takahashi, K., US Patent 6,281,296, assigned to DuPont Dow Elastomers LLC (Aug 28, 2001) 39. Ojakaar, L., US Patent 4,983,680, assigned to DuPont Co. (Jan 8, 1991) 40. Brasen, W. R., and Cleaver, C. S., US Patent 3,467,635, assigned to DuPont Co. (Sep 16, 1969) 41. Tabata, Y., Ishigure, K., and Sobue, H., J. Poly. Sci., A-2:2235 (1964) 42. Kojima, G., and Hisasue, M., Makromol. Chemie 182:1429–1439 (1981) 43. Morozumi, M., Kojima, G., and Abe, T., US Patent 4,148,982, assigned to Asahi Glass Co. Ltd. (Apr 10, 1979) 44. Kojima, G., Kojima, H., and Tabata, Y., Rubber Chem. Technol. 50:403 (1977). 45. Harrell, J. R., and Schmiegel, W. W., US Patent 3,859,259, assigned to DuPont Co. (Jan 7, 1975) 46. Wachi, H., Kaya, S., and Kojima, G., US Patent 4,645,799, assigned to Asahi Glass Co., Ltd. (Feb 24, 1987) 47. Ito, Y., and Wachi, H., US Patent 4,758,618, assigned to Asahi Glass Co., Ltd. (Jul 19, 1988) 48. Grootaert, W. M. A., and Kolb, R. E., US Patent 4,882,390, assigned to Minnesota Mining and Manufacturing Co. (Nov 21, 1989) 49. Grootaert, W. M., Kolb, R. E., and Worm, A. T., “A Novel Fluorocarbon Elastomer for High-Temperature Sealing Applications in Aggressive Motor Oil Environments,” paper presented at ACS Rubber Division meeting, Detroit, Michigan (Oct 17-20, 1989) 50. Hull, D. E., Automotive Polymers & Design, pp. 18–21 (June, 1990) 51. Bauerle, J. G., and Schmiegel, W. W., US Patent Application Publication No. US 2003/0065132 (Apr 3, 2003) 52. Bauerle, J. G. and Tang, P. L., SAE World Congress, Detroit, Michigan (Mar. 2002) 53. Schmiegel, W. W., “A Review of Recent Progress in the Design and Reactions of Base-Resistant Fluoroelastomers,” paper presented at International Rubber Conference, Nurenberg, Germany (Jun 30–Jul 3, 2003) 54. Moore, A. L., Elastomerics, pp. 14–17 (Sep, 1986) 55. Moore, A. L., US Patent 4,694,045, assigned to DuPont Co. (Sep 15, 1987) 56. Stevens, R. D., and Moore, A. L. “A New, Unique Viton® Fluoroelastomer With Expanded Fluids Resistance,” paper presented at ACS Rubber Division meeting, Cleveland, Ohio (Oct 21–24, 1997) 57. Schmiegel, W. W., and Tang, P. L., US Patent Application Publication No. US 2003/0004277 (Jan 2, 2003)

6 Processing of Fluoroelastomers 6.1

Introduction

Processing methods used for other synthetic elastomers can be applied to fluoroelastomers, sometimes with considerable adjustment to take account of special characteristics of the polymers and their compounds. The slow relaxation rates of fluoroelastomers cause difficulties in mixing, extrusion, and injection processes normally run at high shear rates. Many curatives and additives are insoluble in fluoroelastomers, so special procedures may be necessary to get adequate dispersion in compounds for reproducible curing. Many fluoroelastomer compounds give problems in molding operations, including the opposite situations of undesired sticking to mold surfaces, and of inadequate adhesion to metal inserts. The relatively low volume of fluoroelastomer parts production requires that equipment used for other high-volume elastomers be adapted to fluoroelastomer processing.

6.2

Mixing

Fluoroelastomer compounding is usually carried out in relatively small batch mixing equipment, since materials costs are high and production volumes are low. However, most mixing has shifted from open rubber mills to internal mixers as volume has increased and quality control has become more stringent. A major consideration for a production facility handling several other elastomers is to avoid contamination of fluoroelastomer compounds. Strict cleanup procedures are necessary to assure that hydrocarbon elastomers, oil, grease, and other incompatible contaminants are removed from equipment before processing fluoroelastomers.

of some ingredients must be used to get adequate dispersion and curing performance. Necessary uniform dispersion of curatives is particularly difficult in compounds cured with the bisphenol system. Bisphenol AF crosslinker and quaternary phosphonium salt accelerators are high-melting solids that must be micropulverized to fine particles for dispersion in compounds. Because many fabricators would have problems in attaining the uniform dispersion necessary for reproducible curing, polymer producers offer these curatives already mixed with fluoroelastomer in the form of concentrates or precompounds. For example, DuPont Dow sells the VDF/HFP dipolymer Viton® E-60 as a gum polymer to be mixed with curative concentrates and also as a precompound, Viton® E-60C, with Bisphenol AF (BpAF) and benzyl triphenyl phosphonium chloride (BTPPC) in the proper amounts for curing. The curative concentrates VC-30, 50% BpAF in dipolymer, and VC-20, 33% BTPPC, are readily incorporated by fabricators in the amounts chosen for desired cure characteristics. Similar curative concentrates are offered by other fluoroelastomer suppliers. DuPont Dow and Dyneon also offer precompounds containing these curatives in the form of a mixture of BTPP+BpAF- salt with additional BpAF (weight ratio BpAF/BTPP+ about four). The isolated mixture is a low-melting glass that is readily dispersed (offered by DuPont Dow as VC-50). Fluoroelastomer suppliers offer a number of bisphenolcurable precompounds, often including processing aids, for various applications. These offerings give fabricators assurance of reproducible curing characteristics and considerable flexibility in compounding for particular processing characteristics and vulcanizate properties.

6.2.2 6.2.1

Compounding Ingredients

Ingredients should be kept in sealed containers stored in cool, dry areas. Particular attention should be paid to metal oxides and hydroxides that may interact with moisture and carbon dioxide in ambient air. Excessive moisture pickup by polymer, filler, and other additives may cause erratic curing and flaws such as porosity in fabricated parts. Special forms

Mill Mixing

Two-roll mills have been used for rubber compounding since the middle of the nineteenth century. Originally they were also used for mastication of natural rubber, to break down high molecular weight fractions. However, such breakdown is generally not desirable for synthetic elastomers, including fluoroelastomers, which are designed to have molecular weight distributions optimized for various process-

104 ing methods and end uses. Mills are suited to lowvolume production of specialty fluoroelastomer compounds, but have been largely replaced with internal mixers. In many production operations, mills are used for sheeting off stock from internal mixers or for warm-up of compounds for sheet feed to extruders or calenders. A typical rubber mill is shown in Fig. 6.1.[1] The mill consists of two closely spaced parallel, horizontal rolls made from hard castings supported by strong bearings in a mill frame. The counter-rotating rolls are driven at different speeds to maintain a friction ratio of 1.05 to 1.25, transporting the rubber over the top of the roll to the nip area, then through the nip with small adjustable clearance (usually 2–6 mm) to subject the stock to high shear stresses. To get good mixing, the amount of stock and mill clearances used should result in formation of a smooth band on one roll, with a rolling bank of stock in the nip. The surface speed of the slow roll is about 50 cm/s, allowing the mill operator to cut the band diagonally and fold the cut portion over the remaining band for blending. The mill rolls are hollow to allow flow of coolant for control of roll and stock temperatures. A number of safety features are incorporated into mill design, including shutoff switches and brakes to stop the rolls quickly, means to move the rolls apart, and guards to keep hands and tools away from the nip area. Stringent operator training and adherence to safe procedures are necessary to avoid the inherent hazards involved in mill operation. A typical mill mixing procedure is given in a 1975 DuPont product bulletin.[2] The fluoroelastomer described is a VDF/HFP dipolymer precompound, Viton® E-60C, containing about 2 phr Bisphenol AF and 0.55 phr BTPPC accelerator. The medium-viscosity polymer was designed with a considerable high

Figure 6.1 Rubber mixing and sheeting mill.[1]

FLUOROELASTOMERS HANDBOOK molecular weight fraction to impart enough cohesive strength for good mill mixing. A batch size of about 40 kg is recommended for a production-scale mill (about 50 cm diameter and 150 cm length). The compound recipe contains 100 phr E-60C precompound, 30 phr MT black, 6 phr calcium hydroxide, and 3 phr magnesium oxide. The clean mill is cooled to about 25ºC and the nip is adjusted to about 3 mm. The polymer is added to the mill for banding. Ordinarily, the fluoroelastomer bands on the fast roll, but may be forced to the slow roll by increasing the temperature slightly on the slow roll. The nip is adjusted to about 5 mm to get a rolling bank in the nip. The banded polymer is cut about three times from each side to get a uniform sheet on the roll. The powdered ingredients are preblended and added at a rapid uniform rate across the width of the nip. Loose filler that falls through the nip is swept from the pan and added to the batch before cutting the sheet. Further mixing is carried out by cutting and blending the sheet about four times from each side. The mixed sheet is cut off the mill and cooled. About fifteen minutes of milling time is usually adequate for the total operation described. Cooling of the slab is accomplished by dipping in a water tank, or by water spray or forced air. If water cooling is used, it is important to dry the stock with forced air before storing it. Mill mixing is difficult, especially on a production scale, for a number of gum fluoroelastomers. Polymers with narrow molecular weight distribution and low ionic end group levels may not have adequate cohesive strength to form a smooth, holefree band on a single roll. When addition of powdered ingredients is attempted, the stock and loose fillers may drop off the rolls into the pan. Subsequent consolidation of such a batch is time consum-

6 PROCESSING OF FLUOROELASTOMERS ing and messy at best. Very high molecular weight fluoroelastomers undergo significant breakdown during initial passes through a tight nip of a cold mill, with resultant deterioration of vulcanizate physical properties. On the other hand, bimodal blends (formed by latex mixing before isolation) have excellent milling characteristics, with negligible breakdown of high molecular weight fractions. High viscosity elastomers with considerable long-chain branching and gel fractions may also break down during milling, possibly improving subsequent processing characteristics (e.g., extrusion).

6.2.3

Internal Mixers

Even for modest production scales, internal mixers have largely replaced mills for fluoroelastomer compounding. Well-designed laboratory mixers have become available in recent years, allowing reliable development of compounds with small amounts of elastomers. Mixing is accomplished inside a closed chamber with rotating kneading rotors. The major type is the Banbury mixer, developed in the early twentieth century and shown in Fig. 6.2.[3] This design has tangential rotors that do not intermesh. Since the paths of the rotor tips do not touch, the rotors can be driven at different speeds. Dispersive mixing is accomplished in high-shear tapering nip regions between rotor tips and the mixer wall. Distributive mixing occurs by transfer of material from one rotor to the other and around the mixing chamber. Most Banbury mixers have two-

105 wing rotors, but four-wing designs have been developed for faster mixing. In the 1930s, mixers with intermeshing rotors were developed, such as the Shaw Intermix shown in Fig. 6.3.[3] Tangential and intermeshing rotor geometries are shown in Fig. 6.4. Intermeshing rotors provide dispersive mixing in the nip between the rotors and facilitate transfer of material from rotor to rotor. Modern internal mixers are available in a wide range of sizes and have variable speed rotors with special helical profiles and cooling for control of batch temperature and energy input.[4] Ram position and pressure can be controlled to promote optimum mixing. With the sensors and controllers provided, computer-controlled mixing lines have been developed, as shown in Fig. 6.5.[5] Such systems include controls of ingredient feeds and mixed compound takeoff equipment.

Figure 6.3 Shaw Intermix.[3]

(a)

[3]

Figure 6.2 Banbury mixer.

(b)

Figure 6.4[3] Tangential (a) and intermeshing (b) rotor designs.

106

FLUOROELASTOMERS HANDBOOK

Figure 6.5 Mixing line with computer control.[5]

Conditions for Banbury mixing of a VDF/HFP dipolymer compound are described in Ref. 2. The recipe is the same as that in the mill mixing example of Sec. 6.2.2, a Viton® E-60C precompound mixed with 30 phr MT black, 6 phr calcium hydroxide, and 3 phr magnesium oxide to get a medium hardness stock. The mixer used is a 3D Banbury with a 600-hp DC drive, mixing chamber capacity of about 80 liters, and two-wing rotor design. Total compound weight of 104 kg with specific gravity of about 1.8 results in a fill factor of about 0.75. The mixer and associated auxiliary equipment are cleaned to avoid potential contamination of the fluoroelastomer mix. Full cooling water is applied to rotors and shell, rotor speed is set at 30 rpm, and ram pressure is set at 0.4 MPa. The fluoroelastomer precompound in sheet form (75 kg) is added and the ram put down. Then the ram is raised and the blended powder ingredients are added. The ram is put down and the batch is mixed for about two minutes; measured mixer temperature increases from 30ºC to about 75ºC. The ram is then raised to allow unconsolidated material to be swept down into the mix. The ram is put down and mixing is continued for another minute, as temperature increases to 100ºC. The ram is raised to allow a final sweep, and then is put down for continued mixing for 15–30 seconds. The batch is dumped to a mill for cooling and sheeting. Total mixing time is 3–4 minutes, and final stock temperature is no more than about 120ºC.

Some modifications of Banbury mixing procedure may be necessary for other fluoroelastomer product forms, or curatives. For polymer in the form of pellets, an “upside down” charging procedure is recommended, with fillers and other powdered ingredients added first, followed by the elastomer pellets. If the curing system has short scorch times (e.g., diamine or some peroxide systems), the curatives may have to be added in a second mixing pass after incorporation of other ingredients and cooling of the stock. More detailed procedures and a trouble-shooting guide are given in a recently updated Processing Guide[6] for fluoroelastomers.

6.3

Extrusion

Extruders of varying design are used for fluoroelastomers and their compounds. As described in Sec. 4.8, dewatering and drying extruders are used in production of fluoroelastomer gums. In the DuPont continuous polymerization process, precompounds have been made by continuous feed of curatives along with isolated polymer to an extruder with high-shear mixing elements. Such compounding requires close control of all feeds on an instantaneous basis, since material goes through the extruder essentially in plug flow, with minimal back mixing. The compounding extruder, thus, provides mainly dispersive mixing, with little distributive mixing. With the growth of the precompound market

6 PROCESSING OF FLUOROELASTOMERS and resulting proliferation of products, along with requirements for close control of precompound composition, precompound production was switched to more versatile batch internal mixer systems. Short extruders may also be used to take warm isolated polymer from a dryer, or mixed stock from an internal mixer, and form it into sheet. However, the main use for extruders in fluoroelastomer processing is to convert mixed stock into forms suitable for curing. Extruded solid cord or tubing may be cut into preforms for press molding of seals. Extruded heavywalled tubing may be cured in an autoclave for hose applications. Extrusion through cross-head dies is used for coating of wire and cable, and for hose veneer layers on mandrel supports. Fluoroelastomer suppliers offer specially designed polymers and compounding for fast, smooth extrusion of profiles with good dimensional control. In Vol. 2 of this PDL Handbook Series, Ebnesajjad[7] describes many design and operating aspects of extruders used for melt-processible fluoropolymers. Parts of a typical single-screw extruder are shown in Fig.6.6.[7] Features of a typical

107 extrusion screw are indicated in Fig. 6.7.[7] However, the operating conditions used for fluoroplastics, with temperatures of 200ºC to 400ºC, are not applicable to extrusion of fluoroelastomers, except for a few specialty thermoplastic fluoroelastomer products. Since elastomers are essentially amorphous, viscous liquids, melting is not required. Extrusion of compounds must be carried out at temperatures below about 120ºC to avoid premature curing. Early screw extruders for rubber had short barrels, with length/diameter ratios (L/D) 6:1 or less, and required hot feed, using mills to break down and preheat the rubber to reduce its viscosity before extrusion. After World War II, extruder manufacturers started to develop machines with longer barrels (L/D = 12:1 or more) to handle cold feed of rubber strip.[8] Modern cold feed extruders are suitable for most synthetic rubbers, including fluoroelastomers. The following description of these extruders is based largely on a 1985 review by Kemper and Haney.[8] From Fig. 6.6, elastomer fed to the extruder is moved through the barrel by a screw to a die to get

Figure 6.6 Typical single-screw extruder with a vented barrel.[7]

Figure 6.7 Conventional screw design.[7]

108 the desired extrudate cross section. The screw is driven at controlled speed with a motor and gear reducer. The drive must be capable of supplying adequate torque over a wide speed range (up to 200 rpm) with precise speed control. In most modern extruders, a variable speed DC drive is used. Torque of DC drives decreases with increasing speed; this matches the lower torque required as polymer viscosity also decreases with increasing shear rate. The shank of the screw connects to the drive mechanism supported by a thrust bearing, which must withstand the force on the screw from the back pressure of the rubber being forced through the die at the other end of the barrel. For steady operation of a cold feed extruder, the design of the hopper and feed section must be adequate to assure uniform, uninterrupted feed. Machine features may include non-restrictive guards, roller feed assists, deep screw flights in the feed section, uniform temperature control, and alarms to warn of loss of feed. However, rubber strip with constant width and thickness must be properly introduced into the extruder. Ordinarily the strip is fed through power assist rollers to one side of the screw. The output of an extruder varies with the inside diameter (D) of the barrel. Common sizes are 60, 90, 115, and 150 mm (2.5, 3.5, 4, and 6 inches), with output approximately doubling with each size increment. Length (L) of the barrel is measured from the end of the feed throat section to the die. Cold feed extruders have L/D of at least 12:1. Extruder barrels are made of high-strength steel with thickness capable of resisting pressures of some 70 MPa (10,000 psi). Usually a high-strength steel alloy liner is provided for wear and corrosion resistance. A heating and cooling system is provided to control temperatures of the internal surface of the barrel and the external surface of the screw. The objective of temperature control is to adjust the coefficient of friction so that the rubber slips along the screw while adhering slightly to the barrel surface. Usually, a modern extruder has at least five temperature-controlled zones: three for the barrel, one for the screw, and one for the head. In most rubber extruders, an ethylene glycol/water mixture is circulated through jackets around the barrel and through the core of the screw. Electric immersion heaters and a heat exchanger for cooling are used to get a maximum temperature near 120ºC.

FLUOROELASTOMERS HANDBOOK The screw controls rubber output rate and stability, temperature rise, backpressure, uniformity of mixing, and compression of the compound into a solid mass. The ideal screw design that would accomplish all these tasks efficiently for a wide range of compounds doesn’t exist, so design compromises are necessary in practice. The simplest screw designs, such as that shown in Fig. 6.7, have three discrete sections. The feed section has a relatively deep channel with a constant pitch (helix angle). The compound is compressed in a transition zone with a reduction in channel depth and/or helix angle. Material is pumped to the die by a metering section with constant channel depth and pitch. Screw flights are only partially filled in the feed zone, but are completely filled in the metering zone. More complex screw designs have been devised to optimize output with minimal temperature rise and improved mixing of compound. These may include mixing sections with special elements or extended length, and barrier sections that promote mixing or set up regions of low pressure for venting of volatiles without loss of compound. Ordinarily, a vented barrel design such as that shown in Fig. 6.6 results in significant reduction in output. The original clearance between barrel and screw for rubber extruders is about 0.08 mm per 25 mm (3 mils per inch) of barrel diameter. To minimize wear, screw flights may be hardened or made with wear-resistant materials. As shown in Fig. 6.6, a breaker plate and screen pack are positioned at the entrance to the head to generate back pressure on the screw and to remove foreign particles from the compound. The extruder head directs the rubber through a shaping pin and die, and has a streamline design with accurate temperature control to provide uniform delivery to the die. A straight head, shown in Fig. 6.8,[8] is used for extrusion of profiles such as cord or tubing. A tubing die is shown in more detail in Fig. 6.9.[7] A crosshead die, shown in Fig. 6.10,[8] is used for coating wire or extruding veneer on a mandrel as the inner layer of fuel hose. Careful design is necessary to obtain uniform rubber flow and concentric coating of the wire or mandrel. Figure 6.11[7] is a schematic of an extrusion line for wire coating, or hose veneer, showing auxiliary equipment for feeding the wire, or mandrel, and for taking up the coated material. Dimensions of the extrudate must be monitored and controlled to get the desired shape before curing of the rubber.

6 PROCESSING OF FLUOROELASTOMERS

109

Figure 6.8 Straight extruder head.[8]

Figure 6.9 Tube die.[7]

Figure 6.11 Extrusion line.[7]

Figure 6.10 Cross-head.[8]

110 Conditions for extruding preforms of a medium viscosity bisphenol curable VDF/HFP dipolymer compound are suggested in Ref. 2. A relatively cool barrel and screw are used to keep stock viscosity high enough to minimize entrapment of air. Care is taken to ensure that the stock is dry, especially to remove any surface condensate that may have formed on material taken from cold storage. Approximate temperatures suggested are 30ºC for the screw, 55ºC for the barrel, 65ºC for the head, and 95ºC for the die. Low screw speeds are suggested to assure extrusion smoothness. As with fluoroplastics,[7] a fluoroelastomer compound shows melt fracture when shear rate through the die exceeds a critical value related to the characteristic relaxation rates of the polymer chains. Extrusion conditions must be adjusted to get the desired cross section for accurate size of preforms for compression molding. Ordinarily, the stock has sufficient scorch resistance so that startup material and stock left in the extruder head at shutdown can be recovered for reuse. Extruded cord or tubing may also be cured in an autoclave under steam pressure (0.55 to 0.70 MPa to get curing temperatures of 155ºC to 165ºC) for an hour or more. Ram extruders such as the Barwell Precision Preformer[9] are widely used to make blanks of rubber compound with suitable shape and weight for use as preforms in compression molding. Typical barrel capacities are 40, 60, or 80 liters of compound. Various die designs (usually for rod, strip, or tubing extrusion) are available for extrudate diameters up to 190 mm. Ram pressures are usually up to 35 MPa. Depending on design, rubber compound can be loaded either at the front or rear of the machine. Rear loading allows the die assembly to remain in place for more efficient resumption of extrusion. A variable speed rotary cutter at the die face allows for cutting of preforms to accurate size. With manual controls, preform accuracy of ±1.5% by volume can be attained. Machines with weigh-scale loop feedback controls can achieve ±1% accuracy. For extrusion of a medium viscosity fluoroelastomer compound, the stock is usually warmed on a mill before charging, barrel temperature is set at about 90ºC and the die at about 70ºC. A screen is used to remove large particles of contaminants and to increase pressure at the die so that air bubbles are not extruded. Barwell extruders are particularly useful for process-

FLUOROELASTOMERS HANDBOOK ing of high-cost specialty fluoroelastomers used for limited volumes of precision molded parts.

6.4

Molding

Fluoroelastomer parts may be fabricated by compression, transfer, or injection molding. All these processes are used commercially, with a number of factors determining the choice for a particular compound or application. Such choices are not always optimum, since fabricators may be forced to use available equipment because of lack of capital funds for upgrading to more modern molding processes. Some general considerations, discussed in the following section, apply to all fluoroelastomer molding operations.

6.4.1

General Considerations

Cure characteristics of rubber compounds must include a delay in the onset of crosslinking to allow sufficient time for the stock to flow at elevated temperatures to fill mold cavities. Then the cure should proceed rapidly to minimize the required time in the mold. Special measurements of scorch time at high temperature may be necessary to assure that a compound is usable for injection molding, since the stock may be subjected to high temperatures for a considerable time before injection into the mold. Compounds should be designed for good mold release, and should not leave residues on mold surfaces, which could lead to subsequent sticking of parts and unacceptable surface quality. The choice of cure system plays a large part in this. The original diamine cure systems generally give mold dirtying and poor quality surfaces on parts after a few heats, thus these systems are little used. Bisphenol cures can be formulated for good release, and are widely used for molded parts. Peroxide systems give variable results. The relatively slow cures of fluoroelastomers with bromine cure sites often give demolding problems, while the fast cures with iodine cure sites can give clean demolding. Mold release agents may be incorporated into compounds. These agents are incompatible with the fluoroelastomer at molding temperatures, so that they migrate quickly to the interfaces between stock and mold surface to facilitate release. When such internal mold release agents are

6 PROCESSING OF FLUOROELASTOMERS effective for a given compound, they are preferable to external mold release agents, which must be sprayed on mold surfaces periodically. Volatiles may be released from the cured stock when the mold is opened, so adequate local ventilation should be provided to protect operators. A concern with peroxide cures is the release of methyl bromide and/or iodide. The amounts of these materials can be minimized by keeping the ratio of radical trap (usually TAIC or TMAIC crosslinker) to peroxide high enough so that methyl radicals are intercepted by the trap, rather than by halide groups on polymer chains. Peroxide decomposition also results in significant amounts of low molecular weight organic compounds, such as acetone and isobutene, which will be evolved on demolding of the hot cured parts. In bisphenol cures, inorganic base levels should be set high enough to avoid significant hydrogen fluoride evolution. For good control of dimensions and surface characteristics of parts, molds should close tightly and cleanly at the flash line. Surfaces should be free of nicks and pits. Hard chrome plating of mold surfaces is recommended to minimize mold fouling.[6] However, chrome plating at sharp edges may show excessive wear. Molds made of nickel chrome alloy have hard wearing surfaces with good release characteristics.[10] Mold platens which hold mating mold plates should be free of distortion. The platens should be provided with heaters that allow good control of mold temperature. Compared to other elastomers, fluoroelastomers have higher thermal expansion coefficients and are cured at higher temperatures, so higher shrinkage is usually observed in cured fluoroelastomer parts. Shrinkage increases with higher molding temperatures, and decreases with higher levels of filler and metal oxides in compounds. A bisphenol-cured VDF/HFP dipolymer compound with 30 phr MT black shows 2.5%–3.2% shrinkage after molding at 177ºC–204ºC. An additional 0.5%–0.8% shrinkage occurs after post curing in an oven at 204ºC– 260ºC, as water and other volatiles are removed.[2] Shrinkage may be higher for fluoroelastomers with higher fluorine content. For close control over dimensions, shrinkage should be measured for a given compound and molding conditions, to allow proper design of mold cavities. Some fabricators may use molds designed for nitrile rubber to make fluoroelastomer parts. This may necessitate restrictions on

111 fluoroelastomer composition, filler level, and cure temperature to get finished parts within size tolerances.

6.4.2

Compression Molding

Compression molding, depicted in Fig. 6.12,[11] is the oldest and simplest way of making rubber parts, and is widely used for fluoroelastomers. In this process, a piece of uncured rubber is placed in the mold cavity. This is usually a preform with weight slightly greater than that of the finished part. The mold is then closed and held under hydraulic pressure at the desired temperature until the part is cured. Finally, the mold is opened for removal of the part and attached flash (excess rubber that is subsequently trimmed from the final part). Compression molding has several advantages for fabrication of fluoroelastomer parts. Loss of expensive material may be minimized by careful control of preform size to keep the amount of flash low. The process is advantageous for relatively small production volumes of parts of any size. Equipment costs of molds, presses, and auxiliaries are low. Compression molding works best with stocks of medium to high viscosity. Thus, fluoroelastomers with high molecular weight may be processed readily to give parts with excellent mechanical properties and environmental resistance.

Figure 6.12 Compression molding process.[11]

112 Among the disadvantages for compression molding is high labor cost, since considerable operator attention is needed for preparing and loading preforms, closing the mold, and removing cured parts. Quality of parts may be variable, largely because of variations in mold cycle time associated with manual operations. Temperature control may be compromised by variations in the length of time the mold is open, so rate and state of cure may vary considerably, affecting part dimensions and physical properties. Other molding processes may be better for high volume production of standard parts and for production of intricate parts with long flow channels in the mold. For small-scale molding, as in laboratory preparation of parts for evaluation and measurement of properties, compression molds are in the form of two plates that are removed from the press for loading and unloading. For most production operations, the mating mold plates are attached to recesses in the mold platens. In either case, mold temperature is set and controlled by the press heating system. Actual mold temperature may be significantly lower than the set press temperature, so periodic monitoring of mold temperature is desirable to avoid undercured parts. For production of high-quality compression molded parts,[6] preforms should be carefully prepared. Weight should be 6%–10% higher than that of the finished part, and preforms should be dense and free of trapped air. Proper size is necessary to assure complete filling of the mold cavity with minimal flash. Trapped air could lead to blisters in the final parts. Stock viscosity should be high enough at molding temperature to force air from the mold cavities, but not so high that backrinding occurs on demolding. Proper mold filling is facilitated by delayed bumping of the press to higher pressure after the stock has been heated to get good flow. Backrinding, rough edges on parts, is caused by expansion upon demolding, usually at the parting line of the mold cavity. Poor mold flow and backrinding may also occur if the stock is too high in viscosity or is too scorchy (curing prematurely before the mold cavity is filled). Blisters of various kinds may appear in molded parts for a number of different reasons:[6] undispersed particles, contamination by a different compound, trapped air, inadequately dispersed processing aid, entrained water (e.g., from condensate on cold stored

FLUOROELASTOMERS HANDBOOK stock), poor dispersion of curatives, or undercure. Many of these problems can be avoided by proper mixing and storage procedures for the compound, and assuring that equipment cleanup is adequate to avoid presence of small amounts of nonfluorinated rubber compounds. Parts undercured in the mold may exhibit sponging, splits, or fissures after oven post curing. Possible corrective measures include increasing accelerator level in the compound, increasing mold temperature, and/or molding time. Parts with thickness greater than 5 mm are more likely to form fissures on post curing. In addition to the corrective measures mentioned, it may be necessary to ramp up the post cure oven temperature gradually to allow escape of volatiles without blowing the parts. Multiple cavity molds should be designed to assure uniform pressure and temperature are maintained for all cavities. Loading fixtures[12] are useful when a large number of cavities must be loaded individually by a gloved operator while the mold is hot. Such fixtures must be light in weight and easy to operate. For parts such as shaft seals, metal inserts, as well as rubber preforms, may be loaded more readily with a properly designed fixture. Less complicated fixtures may be used for unloading parts from a mold. Ebnesajjad[13] describes compression mold designs in more detail.

6.4.3

Transfer Molding

The transfer molding process, shown in Fig. 6.13,[11] involves using a piston and cylinder device to force rubber through small holes into the mold cavity. A piece of uncured compound is put into a part of the mold called the pot, and a plunger then pushes the stock into the closed mold through a sprue. The mold is kept closed while the rubber cures. The plunger is then raised, and the transfer pad material is removed and discarded. The mold is opened for removal of the part; then the flash and sprue material is trimmed off and discarded. Compared to compression molding, transfer molding provides better product consistency, shorter cycle times, and better bonding of rubber to metal inserts.[11] However, considerable material is lost as scrap in the transfer pads, sprues, and flash. The stock must have relatively low viscosity and adequate scorch safety for adequate flow into the mold.[6] The rapid transfer of compound from the pot through

6 PROCESSING OF FLUOROELASTOMERS

113

small sprues to the mold cavities imposes high shear and considerable heat generation, so the stock is heated quickly to curing temperature. Sprue size should be kept as small as is practical, to minimize damage to parts on demolding and tearing from the molded parts. However, sprues must be large enough to allow adequate flow of the compound. Somewhat lower mold temperatures may be usable for transfer molding, to get cure times comparable to those for compression molding. The basic three-plate multiple cavity transfer mold is more complex and expensive than a compression mold, but is better suited to molding intricate parts or securing inserts.[14] Only a single piece of rubber is used to fill all mold cavities in a heat, so preparation of preforms is much simplified. Since the mold is closed during filling, flash is minimized through gates and vents. Several transfer molding process variants and mold designs are described by Ebnesajjad.[13]

6.4.4

Injection Molding

Ram or piston injection units are also used in the rubber industry.[6] These are somewhat similar to the transfer molding process. The rubber compound is fed to a heated cylinder, warmed to a predetermined temperature, and is then forced by a hydraulic ram through a nozzle, mold runners, and restrictive gates into the heated mold cavity. Ram injection units are lower in cost than reciprocating screw units, but are less efficient, especially for high-viscosity stocks. An alternative to the horizontal machine shown in Fig 6.14 is a vertical ram or screw type machine with a horizontal mold parting line. This may be more desirable for complex mold designs[6] requiring runner systems or metal inserts. Vertical machines also take up less floor space. Of all the molding processes, injection molding[11] provides the maximum product consistency, most control of flash, and shortest cycle times. However, injection molding is not suited for all compounds and molding applications, has the highest investment cost in molds and auxiliary equipment, and typically has considerable scrap in runners and sprues. The process is most suited to production of high volumes of standard parts. Injection molding machines have been highly developed for molding of thermoplastics, and

Injection molding is the most advanced method of molding rubber products.[11] In this process, all aspects of how the rubber gets into the mold and is cured are automated. The main steps in a typical rubber injection molding process are shown in Fig. 6.14[11] for a reciprocating screw machine. The compound is usually fed to the screw as a continuous strip, but sometimes is fed as pellets from a hopper as in plastics processing. The strip is worked and warmed by the screw in a temperature-controlled barrel. As the stock accumulates at the front of the screw, the screw is forced backward a specified amount in preparation for a shot. Screw rotation is stopped, and the screw is pushed forward to inject a controlled amount into the closed mold. While the rubber cures in the heated mold, the screw is initially held in the injection position to maintain a predetermined pressure to consolidate the stock. Then after a preset time, the screw rotates again to refill the barrel. The mold is opened for part removal, then is closed Figure 6.13 Transfer molding for the next shot. process.[11]

Figure 6.14 Injection molding process.[11]

114 are finding increasing use in molding of thermosetting elastomer compounds. Quite different temperature profiles are required for the two types of materials. For thermoplastics operation, pellets are fed to a screw that plasticizes and melts the material at high temperature. The low-viscosity melt is injected into a cold mold to crystallize and solidify the plastic part. For rubber processing, the stock is fed to the screw and warmed to a temperature high enough to reduce the stock viscosity without curing. The stock is injected into a hot mold to effect rapid curing of the parts. Careful design of relatively low-viscosity elastomer compounds for a balance of scorch safety and rapid cure is necessary, along with proper setting and control of stock temperatures in different parts of the equipment. Typical operating conditions are listed in Table 6.1 for injection molding of fluoroelastomers parts with thickness less than 5 mm.[6] These conditions are applicable to molding of low-to-medium viscosity compounds with fast-curing bisphenol systems or with peroxide curing of fluoroelastomers with iodine cure sites. Open time could be longer if parts must be removed manually or if metal inserts must be inserted prior to the next shot (e.g., for molding of shaft seals). Cure times would be longer for parts with thicker sections or for slower cure systems. Higher mold temperatures may be possible with some compounds to get faster cures. Injection molding machinery is described in considerable detail by Ebnesajjad in Volume 2 of this handbook series.[15] A typical injection molding machine, shown in Fig 6.15,[15] consists of these major components: plasticization/injection section, clamping unit, mold including the runner system, and control systems for temperatures and mechanical actions. The functions of the clamp unit are to open and close the mold halves and to hold the mold tightly closed during injection of the fluoroelastomer compound. Injection pressures are high (depending on stock viscosity) to obtain rapid filling of the mold in a few seconds. Thus the force needed to hold the mold closed is very great, with the melt pressure inside the mold exerted over the entire projected area of cavities and feed systems at the mold parting line. Required clamping pressure is a complicated function of injection pressure, projected area, and part thickness. A conservative rule of thumb for fluoro-

FLUOROELASTOMERS HANDBOOK plastics[15] is 0.79 tons per square centimeter of projected area; lower clamp pressures may be usable for fluoroelastomer compounds.[6] Clamp units must be robust to exert the required pressures, but also must open and close rapidly to minimize production time. Common types[15] are the direct hydraulic clamp (Fig. 6.16) and the toggle clamp (Fig.6.17). In either variation, the clamp unit features a fixed platen and a moving platen on which the two halves of the mold are attached. The fixed platen, with the injection half of the mold attached, is mounted rigidly on the machine base and is positioned adjacent to the nozzle of the injection unit. The moving platen carries the ejection half of the mold. The clamp also includes a tailstock platen that the pressure means reacts against to clamp the mold halves together. For this purpose, the fixed and tailstock platens are united by tiebars that also serve as guides for the moving platen. Some modern machines have been developed with other clamping arrangements with no tiebars. The injection unit consolidates the stock to form a fluoroelastomer melt with uniformly dispersed ingredients, and injects it into the mold under controlled conditions. Temperature in the feed system must be controlled well, high enough to get reasonable viscosity for rapid injection, but limited to avoid premature curing before filling the mold. Both screw and ram units are used, but the dominant form is the reciprocating screw injection unit shown in Fig. 6.18,[15] in which the screw is capable of both rotational and axial movement. For elastomers, stock is usually fed to the screw in strip form rather than as pellets from a hopper as shown. The screw should be designed for elastomer extrusion, as described in Sec. 6.3, with relatively high L/D. As indicated in Table 6.1, stock temperature in the extrusion section should be kept below about 120ºC to avoid scorch. The injection sequence was described at the beginning of this section (Sec.6.4.4) as involving four phases. In the melt preparation phase, the screw rotates and conveys the stock to the downstream end of the screw with the barrel nozzle closed by a valve or the presence of a previous molding. The accumulating stock forces the rotating screw back until sufficient melt is available for the next molding. Screw rotation then stops. In the mold filling phase, the barrel nozzle and the screw is pushed forward without rotating, to perform as a ram to inject the stock into the mold. The

6 PROCESSING OF FLUOROELASTOMERS

115

Table 6.1 Fluoroelastomer Injection Molding Conditions[6]

Machine Type

Ram

Screw

Feed zone

80–90

25–40

Middle zone

80–90

70–80

Front zone

80–90

80–100

90–100

100–110

165–170

165–170

205–220

205–220

165–170

165–170

14–115

14–115

Hold pressure

---

½ injection pressure

Back pressure

---

0.3–1

Maximum

Maximum

Total cycle

58–75

43–60

Clamp

48–65

33–50

Injection

3–5

3–5

Hold

---

10–15

Cure (includes hold)

45–60

30 – 45

Open – ejection of parts

10

10

Temperature, ºC Barrel

Nozzle Nozzle extrudate Mold Stock in mold Pressure, MPa Injection

Clamping pressure Time, seconds (for thin parts)

Figure 6.15 Typical injection molding machine.[15]

116

Figure 6.16 Typical direct hydraulic clamp unit.[15] A: Acuating plunger. B: Removable spacer. C: Mold. D: Injection nozzle. E: Fixed platen. F: Movable platen. G: Tiebar. H: Cylinder base plate. I: Clamping cylinder.

FLUOROELASTOMERS HANDBOOK

Figure 6.17 Typical toggle clamp unit.[15] A: Movable platen. B: Fixed platen. C: Mold. D: Front link. E: Rear link. F: Actuating cylinder. G:Tiebar, H: Crosshead link.

Figure 6.18 Typical reciprocating screw injection unit.[15]

high shear rates in the nozzle, sprue, runners, and gates heat the stock so that it reaches curing temperatures during the mold filling operation. In the holding phase, pressure is maintained on the filled mold. At the conclusion of the holding phase, while curing continues in the mold, the screw is again rotated to prepare melt for the next molding. In most elastomer injection molding operations, temperatures in the sprue and runners are high enough so that the stock cures and becomes scrap to be removed from the molded parts. For many of the small parts fabricated from fluoroelastomers, the fraction of such scrap is high and represents a sizeable cost. Cold runner systems have been devised to avoid such scrap losses.[8] In these systems, the sprue and runners are kept at temperatures high enough for plasticization and reasonable viscosity for

injection, but well below temperatures maintained in the mold for rapid curing. Compounds must be carefully designed for scorch times long enough to avoid significant curing during the hold times in the sprue and runners. Gates[15] are the entry points to the mold cavity from the runners. Size and position of gates control flow into the mold. Careful design is necessary to insure complete, symmetrical filling of mold cavities. The gate is usually small relative to the molding and upstream feed system for two reasons. One is that the gate serves as a thermal shutoff valve that cures quickly during the pressure hold phase and solidifies to prevent further flow. The second reason is that the small gate can be easily removed from the molded part without leaving much trace of its presence.

6 PROCESSING OF FLUOROELASTOMERS Most mold designs for injection molding are unique, depending on application, fluoroelastomer compound, and feed system (hot or cold runners). Some standard types can be distinguished, (e.g., twoplate, three-plate, or stack molds).[15] Mold designers must take into account a number of features, including venting, methods of ejecting parts from the mold, cleaning and sweeping of the mold surface between heats, heating methods, and shrinkage.[12] Power systems for injection molding machines must handle a wide range of mechanical movements with differing characteristics.[15] Mold opening is a low-force, high-speed movement, and mold closing is a high-force, low-speed movement. Extrusion involves high torque and low rotational speed, while injection requires high force and medium speed. The modern injection molding machine is a self-contained unit incorporating its own power source. Oil hydraulics have become established as the drive system for the majority of injection molding machines. In these systems, a reservoir of hydraulic oil is pumped by an electrically driven pump at high pressure, typically up to 14 MPa, to actuate cylinders and motors. High and low pressure linear movements are performed by hydraulic cylinders, and rotary movements are achieved by hydraulic motors. However, hybrid machines with the screw driven by electric motors and linear movements by hydraulic power are not uncommon. In recent years, all-electric machines using brushless servo motor technology to power the various movements have come into use. Capital cost is higher, but the electric machines have lower energy consumption, are inherently cleaner, and may have better precision and repeatability than hydraulic systems. Control systems for modern injection molding machines must be capable of handling the complex sequence of operations and necessary options.[15] The range of parameters and adjustments needed to control the process accurately and automatically is broad. Control is ultimately exercised by valves, regulators, and switches, but these are rarely under individual manual control. The norm is now electronic control with varying degrees of sophistication, ranging from partial control by programmable logic controllers up to fully centralized computer control. Injection molding machines are usually offered with choices of control options to suit a variety of end uses and budgets.

117 Troubleshooting injection molding problems[6] may be difficult, since a combination of factors may be involved. Each problem should be analyzed on an individual basis, considering the compound being used, preparation of the stock, the part being made, the injection molding machine and its operation, and the mold. Besides the general considerations noted in Sec. 6.4.1 on molding to avoid potential problems, the following problems are more specific to injection molding: • Air entrapment in the mold will prevent the mold from filling properly. Make sure the feed stock is free of air, provide sufficient back pressure at the nozzle to compress the stock in the barrel, increase injection time, lower injection pressure, and/or make sure the mold is sufficiently vented. • Distortion or rough surfaces of molded articles may result from scorched stock, too long an injection time, too hot a mold, or undersized runners and gates. • Excessive mold flash may be associated with too low stock viscosity, too high injection pressure, too long injection time, too large shot size, or a poor fitting mold. • Excessive nozzle flash may be caused by worn nozzle or nozzle bushing surfaces, too large a nozzle, too high injection pressure, or too low compound viscosity. • Long cure cycles may result from too low barrel or mold temperatures, or an inadequately formulated compound. • Poor knitting may be due to excessive mold release agent, too high mold temperature, too fast a cure rate, or inadequate stock flow.

6.5

Calendering

Uniform thin sheet of fluoroelastomer compounds (for end uses such as die cut gaskets, fabric lamination, and sheet stock) may be produced by calendering. In this operation, a stack of three or four rolls turn at the same surface speed to squeeze the elastomer stock through two or three nips to produce sheet of about 1 mm thickness per pass. A setup for making plied sheet on a cloth liner is shown

118

FLUOROELASTOMERS HANDBOOK

in Fig 6.19[2] The quality of calendered sheet depends largely on the viscosity of the fluoroelastomer compound at the calender.[6] The compound to be calendered should be uniform in dispersion, viscosity, temperature, and flow rate. The fluoroelastomer used should be high enough in molecular weight to give compounded stock with adequate green strength to form uniform bands on the rolls with no holes or tears. However, stock with too high viscosity may give difficulty in attaining consistent thickness across the width of the rolls. Within limits, stock temperature may be chosen to get viscosity in a reasonable range for good calendering characteristics. Use of internal process aids should be minimized, since high levels may lead to slipping or bagging of the stock on the rolls. Suggested roll temperatures are listed in Table 6.2 for fluoroelastomer compounds with different cure systems.[6] Mixed compound must be warmed on a mill with minimum shear to a temperature close to that of the top roll for strip feeding to the calender. The compound should be fed continuously and evenly across the width of the rolls, maintaining only a small bank in the nip between the first two rolls. Maximum roll speed should be 7–10 meters per minute; sheet thickness should be no more than 1.3 mm per pass.[2] Thicker sheet can be made by plying additional material to previously calendered sheet in successive passes, as shown in Fig. 6.19. The first pass is run to get about 1 mm thickness on a high-count cotton liner. In successive passes at lower roll speed, additional 1-mm plies are put on, with the sheet on a liner fed to the lower nip. The roll temperatures noted in Fig. 6.19 are somewhat higher than those suggested in Table 6.2; the higher temperatures are suited to a bisphenol-cured bimodal VDF/HFP dipolymer (Viton® E-60C) with higher green strength than most fluoroelastomers currently offered.

Figure 6.19 Calender operation for plied sheet.[2]

After calendering, the wrapped sheet stock should be allowed to stress relax in the liner for about 24 hours. It may then be rewrapped in the liner required to impart the desired surface texture to the cured sheet.[2] Curing is usually carried out in an autoclave with hot air or steam at temperatures near 170ºC; cure time should be long enough to assure that all the stock reaches curing temperature for an adequate time.[6] When steam is used, pressure should be raised and lowered slowly to prevent blistering. The stock should be wrapped with an outer impermeable layer (e.g., with a film such as PTFE or FEP fluoroplastic) to prevent direct contact with the steam. The liner should be stripped from the stock as soon as possible after curing. Post curing of the sheet is best done by festooning in a forced air oven. For sheets thicker than 6 mm, post cure oven temperature should be increased in steps to the final temperature to prevent blistering.

Table 6.2 Suggested Three-Roll Calender Temperatures[6]

Cure System

Top Roll (°C)

Middle Roll (°C)

Bottom Roll

Diamine (Diak #3)

45–50

45–50

Cool, ambient

Bisphenol

60–75

50–65

Cool, ambient

Peroxide

60–75

55–70

Cool, ambient

6 PROCESSING OF FLUOROELASTOMERS

6.6

Other Processing Methods

Relatively small volumes of fluoroelastomers are processed by other methods for specialty applications. Of these, latex and thermoplastic elastomers are discussed below.

6.6.1

Latex

Fluoroelastomer latex can be used for rubbercoated fabrics, protective gloves, and chemical or heat-resistant coatings. Most fluoroelastomer producers offer latex in limited quantities to processors skilled in latex applications. Typical latex products are based on VDF/HFP/TFE terpolymers (about 68% fluorine) which are readily polymerized to relatively stable dispersions containing 20%–30% solids. These dispersions are further stabilized by pH adjustment and addition of anionic or nonionic hydrocarbon soaps. A water-soluble gum (e.g., sodium alginate) is then added to increase particle size, allowing creaming (actually settling) to concentrated latex (about 70% solids); supernatant serum is discarded. The combination of added soap and gum prevents further particle agglomeration and stabilizes the latex to allow a storage life of several months. Biocides are usually added to prevent unwanted growth of microorganisms. Latex must be protected from freezing or excessively high temperatures during storage and shipping. Formulations used by processors for particular applications are proprietary. Compounding ingredients must be chosen carefully to avoid destabilizing the latex prematurely. Usually, a diamine (Diak #3) or polyamine curative is used with limited amounts of metal oxide and inert filler. Vulcanizate properties obtained from test compounds of Tecnoflon® TN Latex are shown in Table 6.3.[16] Tecnoflon TN is a VDF/HFP/TFE terpolymer (68% F); the latex is about 70% solids. In the compounding examples, a polyamine curative, triethylenetetraamine (TETA), is used with zinc oxide and, optionally, an inert mineral filler, Nyad 400 calcium metasilicate. Curing conditions are mild, chosen because curing is often necessarily carried out at a low temperature to protect substrates on which the compound may be deposited.

119 6.6.2

Thermoplastic Elastomers

Thermoplastic fluoroelastomers are offered commercially by Daikin. These products may be processed by conventional thermoplastics methods without curing. This allows flash from molding and other scrap to be recovered and reused. The materials are A-B-A block copolymers made by the Daikin “living radical” semibatch emulsion process using fluorocarbon diiodide transfer[17] as described in Ch. 4, Sec. 4.6.3. The center elastomeric B block soft segments are made in a first polymerization step. After removal of monomers and recharging a different monomer composition, the plastic A block hard segments are polymerized on the ends of the B blocks. The main commercial product is Dai-el® Thermoplastic T-530. This is described[18] as containing 85% soft segment of composition VDF/HFP/ TFE = 50/30/20 mole % or 33/46/21 wt % (70.5% fluorine) and 15% hard segments of composition TFE/E/HFP = 49/43/8 mole % or 67/17/16 wt %. The basic patent requires that hard segments have molecular weight of at least 10,000 Daltons, corresponding to a degree of polymerization (DP) of at least 140 units, sufficient for crystallization with melting point about 220ºC. Central soft blocks would then have molecular weight at least 110,000 Daltons, with DP = 110 units or more. The high fluorine content of the soft blocks gives the product excellent fluid resistance and a glass transition temperature of about -8ºC. The thermoplastic can be extruded and formed at temperatures above the melting range; after cooling, crystallization of the hard segments gives parts with good dimensional stability at temperatures up to about 120ºC. Typical applications include tubing, sheet, o-rings, and molded parts. Characteristics of T-530 are listed in Table 6.4.[19] To obtain better properties at high temperatures, the thermoplastic fluoroelastomer can be compounded with bisphenol or peroxide systems, molded, and cured at high temperature. Dai-el T-530 can also be compounded at about 90ºC, extruded or molded under high shear at temperatures below the crystalline melting point (110ºC–140ºC), then cured at higher a temperature (about 180ºC).[18] Part distortion would be difficult to avoid in such a process, however.

120

FLUOROELASTOMERS HANDBOOK

A base-resistant thermoplastic fluoroelastomer has been developed by DuPont [20] using similar polymerization techniques. In this material, soft segments are of composition E/TFE/PMVE about 19/45/36 mole % with glass transition temperature –15°C, and soft segments have composition E/TFE about 50/50 mole % with DSC melting endotherm maximum about 250ºC. The thermoplastic fluoroelastomer is readily molded at 270°C to give good physical properties and excellent resistance to

fluids including polar solvents, strong inorganic base, and amines. This composition can be readily crosslinked with ionizing radiation after molding to obtain better properties, with no compounding required. Physical properties of the base-resistant thermoplastic fluoroelastomer are listed in Table 6.5; enhanced fluid resistance is shown in comparison with Dai-el T-530. However, this material has not been offered commercially.

Table 6.3 Typical Properties of Latex Compound[16]

Compound, phr Latex (100 phr rubber) Zinc oxide TETA Nyad 400

Filled

Gum

145

145

10

10

2.5

1.5

20

--

Sodium lauryl sulfate

1

1

Cr2O3

5

5

M100, MPa

2.0

0.8

TB, MPa

4.5

2.9

EB, %

300

800

M100, MPa

2.3

1.0

TB, MPa

5.1

5.2

EB, %

250

650

M100, MPa

5.3

2.3

TB, MPa

6.1

6.2

EB, %

180

450

Physical Properties Press cure (1 h, 90ºC)

Press cure (2 h, 90ºC)

Post cure (1 h, 50ºC)

6 PROCESSING OF FLUOROELASTOMERS

121

Table 6.4 Characteristics of Dai-el® T-530 Thermoplastic[19]

Property

Value

3

Density, g/cm

1.89

Hardness, JIS A

67

Melting point (approximate), ºC

220

Pyrolysis initiation temperature, ºC

380

Thermal conductivity, cal/cm·sec·ºC

3.6 × 10-4

Specific heat, cal/g·ºC

0.3

Low-temperature torsion test, Gehman T50, ºC

-9

Tensile strength, MPa

11

Elongation at break, %

650

Tear strength, kN/m

27

Rebound resilience, %

10

Compression set, 24 h at 50ºC, %

11

Electrical properties 5 × 1013

Volume resistivity, ohm-cm Dielectric breakdown strength, kV/mm

14

Dielectric constant, 23ºC, 1 kHz

6.6

Table 6.5 Properties of Base-Resistant Thermoplastic Fluoroelastomer[20]

Base-Resistant TPE

Dai-el® T-530

M100, MPa

3.4

--

TB, MPa

14.5

--

EB, %

510

--

M100, MPa

5.3

--

TB, MPa

16.9

--

EB, %

270

--

Compression set, % (pellets, 70 h/150ºC)

37

--

Polymer Compression molded

Irradiated, 15 MRad

Chemical Resistance, % wt gain after 3 days/25ºC Acetone

3.6

87.1

Methanol

0.0

0.8

Dimethyl formamide

0.5

48.2

Toluene

1.1

2.0

100.0

48.4

Trichlorotrifluoroethane Butylamine

1.9

Decomposed

122

FLUOROELASTOMERS HANDBOOK

REFERENCES 1. Farrel Mills and Calenders, www.farrel.com (2003) 2. R. H. Burd, Processing Viton® E-60C Type Fluoroelastomers, DuPont Data Sheet V-J-3-401 (1975) 3. Tyre School, www.tut.fi/plastics/tyreschool/moduulit (2003) 4. Farrel F-Series Banbury Mixer, www.farrel.com (2003) 5. R. Bond, The Component Manufacturer – The Roles of the Raw Material Supplier and the Machinery Manufacturer, paper given at ACS Rubber Division meeting, Detroit, Michigan, October 17-20 (1989) 6. Processing Guide, Viton® Fluoroelastomer Technical Information bulletin VTE-H90171-00-A0703, DuPont Dow Elastomers (2003) 7. S. Ebnesajjad, Fluoroplastics, Vol. 2: Melt Processible Fluoropolymers, PDL Handbook Series, Chapter 8: Extrusion, William Andrew Inc., Norwich, NY, (2003) 8. D. Kemper and J. Haney, An Overview of Modern Extrusion Technology, paper given at ACS Rubber Division meeting, Cleveland, OH, October 1-4, (1985) 9. Barwell Preformers, www.barwell.com (2003) 10. Prevention of Mold Staining and Sticking, DuPont Viton® Fluoroelastomer Data Sheet V-J-1-403, 1975. 11. Molding Solutions, www.molders.com (2003) 12. D. N. Raies, Important Factors in the Design of Molds for Compression, Transfer, and Injection Molding of Rubber, paper given at ACS Rubber Division meeting, Cleveland, OH, October 1-4 (1985) 13. S. Ebnesajjad, Fluoroplastics, Vol. 2: Melt Processible Fluoropolymers, PDL Handbook Series, Chapter 10: Other Molding Techniques, William Andrew Inc., Norwich, NY (2003) 14. Rubber Molding, www.hawthornerubber.com (2003) 15. S. Ebnesajjad, Fluoroplastics, Vol. 2: Melt Processible Fluoropolymers, PDL Handbook Series, Chapter 7: Injection Molding, William Andrew Inc., Norwich, NY (2003) 16. Tecnoflon TN Latex, Solvay Solexis Product Data Sheet, www.solvaysolexis.com (2003) 17. M. Tatemoto, T. Suzuki, M. Tomoda, Y. Furukawa, and Y. Ueta, U.S. Patent 4,243,770, assigned to Daikin Kogyo Co. (January 6, 1981) 18. M. Tatemoto, U.S. Patent 5,198,502, assigned to Daikin Kogyo Co., (March 30, 1993) 19. Daikin Technical Information, Dai-el® T-530, www.daikin-america.com (2003) 20. D. P. Carlson, U.S. Patent 5,284,920, assigned to DuPont Co. (February 8, 1994)

Part III Environmental Resistance and Applications of Fluoroelastomers

7 Fluid Resistance of VDF-Containing Fluoroelastomers 7.1

Introduction

Effects of fluids on VDF-containing fluoroelastomers may be physical or chemical in nature. Fluids swell fluoroelastomer vulcanizates to varying degrees, mostly dependent on polymer composition and polarity of the fluid. Some polar solvents (e.g., low molecular weight ketones and esters) are solvents for VDF-based raw polymer and thus swell vulcanizates excessively to cause loss of useful properties. Fluoroelastomers with higher fluorine content (lower VDF content) give lower swell and permeability to most solvents. Swell in most fluids is low enough so that properties and suitability for service are not significantly impaired. Particularly at high temperatures (above 100ºC for aqueous fluids or above 150°C for organic fluids), chemical interactions with polymer, crosslinks, or compound additives may lead to loss of properties.

7.2

Fluid Resistance Data

Table 7.1 is a tabulation of chemical resistance data for VDF/HFP/(TFE) fluoroelastomer vulcanizates, taken from a previous volume in the PDL Handbook Series.[1] The exposure data are mostly based on older diamine-cured compounds with high MgO or PbO levels. While these are little used today, fluid swell mainly depends on polymer composition (VDF or fluorine content) and the polarity of the fluid, not the cure system. Thus, data on fluid swell and property changes for Viton® A (66% F) and B (68% F) are generally applicable to bisphenolcured fluoroelastomers of similar composition. Limited data are also included for peroxide-cured highfluorine types such as Viton® GF (70% F). Observations on chemical effects such as surface cracking should be carefully noted. Information on specialty VDF/PMVE/TFE types is not included. The table also includes data on VDF/CTFE Kel-F elastomers not now available commercially. PDL ratings are listed to rank suitability of various fluoroelastomers exposed to fluids at specified conditions. Rankings of 6 to 9 indicate the material should give satisfactory service under the test conditions. Rankings of 4 to 5 denote borderline perfor-

mance, with relatively high swell and/or considerable property loss. Rankings of 1 to 3 indicate unsatisfactory performance, with excessive swell and property loss. (See Appendix for a more complete description of the PDL Ratings.) In general accord with the standard ASTM designation of FKM for VDF-based fluoroelastomers, Table 7.1 denotes VDF/HFP dipolymers and VDF/HFP/TFE terpolymers as FKM and FKM/TFE respectively.

7.3

Discussion of Results

Table 7.1 lists most of the polar solvents that swell VDF-containing fluoroelastomers excessively. Only limited data on strong aqueous base (e.g., concentrated KOH or NaOH solutions) are listed, and exposure conditions were too mild to show large effects on vulcanizates. Exposure to concentrated aqueous base at high temperature causes dehydrofluorination and chain scission, leading to disintegration of VDF-containing fluoroelastomer parts. Data on exposure to motor oils indicate good resistance at temperatures up to 150ºC, but deterioration of properties at higher temperatures and long exposures. Multifunctional organic amine additives in lube oils may cause embrittlement and surface cracking of VDF/HFP/TFE vulcanizates by excessive further crosslinking and much reduced elongation at break upon long exposure at temperatures above 150ºC. VDF/PMVE/TFE vulcanizates are also attacked by lube oil additives, but the resulting double bonds are not reactive for further crosslinking. Thus embrittlement does not occur and service life is significantly extended, until chain cleavage and loss of crosslinks leads to loss of properties. Data shown in Table 7.1 for steam exposure indicates the advantage of peroxide-curable high-fluorine polymers over diamine- or bisphenol-curable fluoroelastomers. Hydrolysis of double bonds in bisphenol-curable polymers leads to chain scission, with severe property loss. Peroxide-curable high-F fluoroelastomers are also more resistant to degradation by hot water and oxidizing acids (e.g., concentrated nitric acid), but the exposures listed in Table 7.1 are too mild to show significant differences.

126

7.4

FLUOROELASTOMERS HANDBOOK

Fluid Service Recommendations

Fluid resistance of VDF-containing fluoroelastomers varies with polymer composition and cure system. For reactive fluids, exposure temperature and duration often determines whether a given fluoroelastomer compound will give adequate service. This is particularly true for service in automotive fluids. Recommendations for products best suited for specific fluid service conditions can be obtained from fluoroelastomer suppliers. Extensive fluid resistance guides are available on several internet sites maintained by suppliers. DuPont Performance Elastomers maintains an extensive Chemical Resistance Guide[2] on their web site, including fluid resistance of various families of fluoroelastomers. Dyneon includes a

Chemical Resistance Bulletin in their Fluoroelastomer Product Selection Guide section of their web site.[3] Important differences in fluid resistance of various VDF fluoroelastomer compositions and cure systems are summarized in Table 7.2, based on a DuPont Dow Elastomers Viton® Fluoroelastomer Selection Guide.[4] These results indicate the enhanced fluid resistance of types with higher fluorine content, and of peroxide cured specialty types, especially those containing PMVE in place of HFP monomer. Service in automotive fluids is summarized here, but will be discussed further in later chapters on particular applications. VDF-containing fluoroelastomers are not suitable for long-term service in amines or strong aqueous base at elevated temperatures. Some specialty types can give good service in such fluids. Enhanced fluid resistance characteristics of perfluoroelastomers and TFE-olefin fluoroelastomers are described in Chs. 8 and 9.

Table 7.1 Chemical Resistance - FKM, VDF/CTFE, FKM/TFE Fluoroelastomers™ % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time PDt, (0C) Ways) Rating (%) 23

2 1

23 100 100

7 7

6 6 8 8

6 6

149 150

7 3

5 4

g 11

150 205

7 3

9

86 104 92

Acetaldehyde Acetamide

Acetic Acid

20

7

6 0 2 2 2. 1

20 20

30 30

2 1

glacial hot, high pressure glacial

140

20

2

2 1

341

20

7

3

181

20

305

Acetone

with 50% Toluene

A9

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

brittle

26

59

A-22

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-20 A-35

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

not recommended, substantial effect 3M Fluorel (FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

unsatisfactory for use

60

3

1

120

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent 38

87

A-19

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent not suitable for service not recommended, substantial effect

(FKM) 3M Fluorel (FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

unsatisfactory for use not suitable for service

(FKM)

recommended for use <10

2

8 8

A3

not suitable for service

50

23

8

unsatisfactory for use

50

23

11

140

200 375 187

Acetylacetone Acetylene

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent not recommended, substantial effect

recommended (or use

7 7 2

8 8

A4

minor to moder. effect

1 1 1 1

Acetyl Chloride

3M Fluorel (FKM)

may cause si. visible swell/loss of prop,

1

2 1

(FKM)

0xc, resist., little or no effect

moderVsevere swell and/or loss of prop,

56

23

100

62

23 23 25 20

Acetophenone

89

may cause si. visible swett/iqss of prop.

unsatisfactory for use

7

20

(FKM)

sample disintegrated

1 1

Acetic Anhydride

Material Note

minor to moder, effect

23 70

5 30

Resistance Note unsatisfactory 1o* use

7

7

Tensile Modulus Elongation Hardness Strength Change

not suitable for service

4 6 2 8 6 2 1

23 23 25

glacial

Volume

little/no effect-severe CDnd. may cause change

(FKM)

unsatisfactory for use recommended for use <10

ftttle/no effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time POl (days) Rating ( 0 C) (%)

Material Note

38

17

8

8

20

8

2 Z

88

23 50

7

A 1

120

50 100

7 4

1 S

120 6

150

7

8 2 1

297

7

24

A-59

150

7

1

389

2

12

A-59

150

7

2 1

362

2

12

A-59

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

7

1

314

4

18

A-60

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

70

14

9

2

14 40

28

9 8 8 8 9

2 3

Monsanto, Pydraul AC

70 149 <$67 >167 70

2

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Pydraul 150, Monsanto

70

28

8

9

A-6

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Pydraul A-200, Monsanto

70 100 175 70

28 28 3 3

9 8 6 9

3 3 11

83

100

A-3 A-6

O

92

109

A2

70 70

7 14

8 9

O 1

92

113

A2

70

14

9

3

23 70 70

14 14

8 9 9

2 2

205

3

3

31

47

78

A-22

205

3

5

18

71

140

A-9

205

3

6

9

84

126

A-9

51% H2SO4 and others

Aerolube Aerosafe 2300

Aero Lubriplate

Aerosafe 2300W

Shell, aviation piston lube, mineral oil

Aeroshell 4 Air

Aircraft Turbine Fuels

Resistance Note

1

fully saturated urethane polymer

Aircraft Lubricants Aircraft Oils

Hardness Change

8 9

AdipreneL167

Air Compressor Fluid

Tensile Modulus Elongation Strength

28

Acrylonitrile

AeroshelMOO

% Retained

Volume

50

Acetylene Tetrabromide Acid Mixtures

% Change

Humble #ET025 Esso no. 100

Avtur, Shell, kerosine (25% max. arom.) Shell, Avtag, wide cut gasoline

Aircraft Turbine Oils Aeroshell 760 Shell Aeroshell 760, aviation Shell Air no. 505, MIL-L23699

T J 35, aviation, diester base, Exxon

recommended lor use A1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent unsatisfactory lor use DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent moder./severe swell and/or loss of prop,

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

not recommended, substantial effect

65

58

A-5

3M Fluorel (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use unsatisfactory lor use DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent unsatisfactory for use

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist,, little or no effect

3M Fluorel (FKM)

recommended for use

goqg'-exc. resist., moder. effect

3M Fluorel (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

little/no effect-severe cond. may cause change

(FKM)

exc< resists little or no effect

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Aircraft Turbine Oils

Alcohols

Reagent Note

T J 35, aviation, diester base, Exxon

Cone. Temp. Time Ways) ( 0 C) (%)

PDt Rating

Volume

Tensile Modulus Elongation Hardness Strength Change

Resistance Note

205

7

7

10

82

110

A-10

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

250

20

4

29

65

73

A-20

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

denatured

a a

23

recommended for use <10

little/no effect-severe cond. may cause change

6

minor to moder. effect

Alum

2

unsatisfactory for use

Aluminum Acetate

2

Alkazene

23 Aluminum Bromide

recommended for use <10

HNte/no effect-severe cond. may cause change

8

Aluminum Fluoride

a

23

(FKM)

23

a

<10

ttttte/no effect-severe cond. may cause change

23

<10

little/no effect-severe cond. may cause change

a

(FKM)

recommended lor use <10

tittle/no effect-severe cond, may cause change

8

Aluminum Salts

(FKM)

recommended: lor use

8

Aluminum Phosphate

(FKM)

recommended iat use

8

Aluminum Nitrate

(FKM)

recommended for use

a

Aluminum Sulfate

a

23

Ammonia

not suitable tor service

a

23

Amino Acids

1 a

(FKM)

8

Aluminum Chloride

Amines

Material Note

mixed

2

lactams

2

cold

2

hot

2

liquid

2

<10

littie/no effect-severe cond. may cause change

(FKM)

unsatisfactory for use

H

2 2 anhydrous

23

1

gas, cold

23

1

gas, hot

23

anhydrous

25

6

0

a sal ammoniac

8

23

concentrated saturated

20 23

saturated

25

not recommended, substantial effect

3M Fluorel (FKM)

recommended for use <10

little/no effect-severe cond, may cause change

6

concentrated

(FKM)

1 1

Ammonium Chloride Ammonium Hydroxide

not suitable For service

28

a

8

6 28

8

7.5

85

100

A-3

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent may cause si. visible swell/loss of prop,

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

Ammonium Salts

4

Ammonium Sulfate

2

unsatisfactory lor use

1

not suitable for service

8

recommended for use

23 Ammonium Sulfide

modern to severe effect

2

Amyl Acetate

(FKM)

minor to moder * etfect

(FKM)

unsatisfactory for use

20

2

1

308

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

1

280

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

56

1

319

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time PDl Ways) Rating ( 0 C) № 1 1

287

20

56

6 g

0.7

23 25 1-pentanol

21

70

2 56

100

5

9 8

38

180

8 8 8 8 8 8 8 8 9

38

730

38

1095

150

3

23

Amyl Chloride Amyl Chloronaphthalene 23

Amyl Naphthalene 23 di-ester MIL-L-7808

MIL-L-7808

Anderol L826

Anderol L829

3

175

4

175

4

204

7

205

3

8 7

205

3

205

4

oils

Resistance Note not suitable for service

Material Note (FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

minor to moder. effect DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent may cause si, visible svrelf/loss of prop, 1

good-exc. resist., moder. effect

3

(FKM) 3M Fluorel (FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

5 9

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use

<10

little/no effect-severe cond. may cause change

(FKM)

recommended for use <10

tittle/no effect-severe cond. may cause change

(FKM)

recommended for use <10

littte/no effect-severe cond. may cause change

(FKM)

recommended for use 0.7

100

105

A2

1

85

93

A-6

8

73

86

A-7

13

75

95

A-10

9

82

146

A-8

9

A-9

12

A-10

8

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

10

81

96

7

10

81

125

7 7 7

12

A-7 A-1

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-7

9

71

98

A-3

68

99

A-5

4 5

18

47

61

A-5

13

59

68

A-4

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

28

4

20

41

60

A-14

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

149

28

8 7

11

1SO

28

7

11

A-8

150

28

5

A-4

7 7

205

21

205

21

205

di-ester dyes

7 6

Hardness Change

16

205 205

140

Aniline

8 6 6 5

150

di-ester diester high temp, lube, med. viscosity

6 8 9

70

Amyl Borate

Anderol L744 Anderol L774

Tensile I Modulus I Elongation Strength

2

Amyl Alcohol 1-pentanol

% Retained

Volume

70

23

Amyl Acetate

% Change

28

8 8 6 4

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use exc. resist., little or no effect

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use 5

exc. resist., little or no effect

3M Fluorel (FKM)

mitiot to moder. effect moder, to severe effect

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time P D l Ways) Rating ( 0 C) (%)

% Change

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Change

dyes

20

2

9

0.5

20

7

9

3

20

56

9

4

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent 100

100

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

23

6

may cause si. visible swell/loss of prop,

23

4

modef ./severe swell and/or loss of prop,

25

7

8

5

70

2

7

11

70

28

6

26

70

28

3

26

56

3

55

exc. resist., little or no effect

Animal Fats

23

lard

(FKM) 3M Fluorel (FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

good-exc, resist,, moder. effect 60

150

A-29

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

70

Aniline Hydrochloride

Material Note

moder. to severe elf act

4

Aniline

Resistance Note

a

minor to moder. effect

6

may cause $1. visible swell/loss of prop,

a

recommended f of use

(FKM)

8 lard

Animal Oils Ansul's Ether

23

8

23

8

Prestone Prestone, with water

2

unsatisfactory for use

1

not suitable for service

8

recommended for use

50

122

7

7

8

50

122

14

7

10

Aqua Regia 23

Argon Aroc lor 1248

(FKM)

recommended for use

8

lard oil 23

Antifreeze

little/no effect-severe cond, may cause change <10

good-exc. resist., moder. effect

6

minor to moder. effect

6

may cause si. visible swell/loss of prop,

8

recommended for use

(FKM) 3M Fluorel (FKM)

(FKM)

8 Monsanto

8

23

<10

little/no effect-severe cond. may cause change

Monsanto

8

23

<10

little/no effect-severe cond, may cause change

8

Aroclor 1260 Monsanto

8

23

8

23

little/no effect-severe cond. may cause change

<10

8

23

little/no effect-severe cond, may cause change

<10

23 Midcontinent, 85-100

Boscan, 85-100

205

1

205

1

205

7

205

7

(FKM)

recommended for use littfe/no effect-severe cond. may cause change

<10

(FKM)

recommended for use

8

Asphalt

(FKM)

recommended for use

8

Askarel

(FKM)

recommended for use

8

Arsenic Acid

(FKM)

recommended for use

8

Aroclor1254

8

<10

9

6

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3

A-7

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

4

A-2

4

A4

8

9

Itttte/no effect-severe cond. may cause change

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Asphalt

Midcontinent, 85-100

Cone. Temp. Time PDl !days) Rating ( 0 C) (%)

ASTM Hydrocarbon Test Fluid ASTM Oil No. 1

w/8% parapoid 10-C, high aniline lube

ASTM Oil No. 2 ASTM Oil No. 3

ASTM Oil No. 3

lubricating oil

% Change

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Change

Resistance Note

Material Note

205

7

9

3

A4

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

205

7

9

3

AO

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

149

7

8

6

177

7

8

149

3

149

3

149

7

150

3

8 9 9 9 9

150

7

175

21

92

150

7

92

175

7

149

3

exc. resist., little or no effect

3M Fluorel (FKM)

1 1

3M Fluorel FLS 2330 (FKM)

2 0.2

3M Fluorel (FKM) 100

103

A1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

9 9 7

0.6 6

82

110

A3

8

83

115

AO

1.3 2 1

86

95

A-3

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

90

94

A-1

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-5 exc. resist., little or no effect

1.5

23

7

100

14

7 8 9 8 9 8

100

14

9

1

149

3 3

149

7

149

7

8 8 9 5

3.7

149

149

7

149

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use exc, resist,, little or no effect

3M Fluorel (FKM) (FKM)

exc, resist,, little or no effect

3M Fluorel FLS 2330 (FKM) 3M Fluorel (FKM)

4.5 2.5 38.75

87.5

68

A-2

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco101XL:TAIC

7

90

105

93

A-21

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoyl perox.

7

5

48

83

61

A2

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak #1

150

3

9

3

98

100

A9

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1SO

3

8

3

110

95

A5

100

7

4

95

100

A-1

U

150

14

9 7

3

87

122

A-3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

14.6

107

95

A2

14.6

9 8

4

150

4

111

95

A-1

9 6

5

106

95

A1

6

85

58

A3

5 &

10

85

40

A16

9

120

71

A7

6 4

11

107

71

A7

12

75

26

A14

150

41.7

150

41.7

150

83

150

83

150

125

150

125

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

ASTM Oil No. 3

Cone. Temp. Time P D l Ways) Rating (0C) (%)

ASTM Reference Fuel B

ASTM Reference Fuel C

50% isooctane, 50% toluene

U

ASTM Reference Fuel C

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Change

175

7

8

2

177

21

5

20

7

8 S 8 8 9

0

91

90

AO

20

7

9

-0.4

100

108

A-2

25

3

9 8 7

0.1 12

79

94

A-9

7 6

2

74

86

A-4

12

81

118

A-6

9 9

1

90

100

A1

1

96

99

A1

9 8 4

2.5

2

ASTM Oil No.4 ASTM Reference Fuel A isooctane

% Change

20

3

20

3

20

3

20

7

20

7

25

7

7

7

20

1

20

1

9 $

20

3

7

20

3

8

20

7

20

7

7 4

82

90

Resistance Note

AO

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

DuPont Viton B (FKM/TFE); 20 phr MT black 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

15

64

67

A-13

89

136

A-4

76

111

A-2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1 3 2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3

62

86

A-3

6

69

170

A-14

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

7

7

6

77

90

A-4

10

70

78

A-5

20

21

6 6

9

78

76

A-6

20

30

10

20

30

8 8

20

42

60

62

A-5

42

5 5

12

20

8

64

66

A-7

20

180

13

20

180

7 7

25

3

3

exc. resist., little or no effect

25

3

8 a

4.5

U

70

1 1 3

7 €

3M Fluorel (FKM)

recommended for use

21

70

3M Fluorel (FKM)

recommended lor use

20

70

3M Fluorel (FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

Material Note

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

10

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

15

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

16

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

16 14

3M Fluorel FLS 2330 (FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent good-exc. resist moder. effect

3M Fluorel FLS 2330 (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent ASTM Reference Fuel C

ASTM Reference Fuel C

Reagent Note

Cone. Temp. Time PDt Ways) Rating (%)

H)

50% isooctane, 50% toluene

w/15% ethanol;50% isooctane, 50% toluene

w/15% meth.; 50% isooctane, 50% toluene

w/15% ethanol;50% isooctane, 50% toluene

ASTM Reference Fuel D

Atrex

Avtag Avtur Barium Chloride

% Retained

Volume

Tensile Modulus Elongation Strength 79

Hardness Change

70

3

6

17

70

3

6

18

70

7

4

18

56

67

A-12

70

21

5

19

65

78

A-6

70

21

5

17

70

67

A-5

70

30

7

18

70

30

7

20

93

42

5

16

60

83

A-15

5

16

63

68

A-8

70

180

7

19

70

180

6

22

70

208

6

17

72

78

A-6

100

3

5

20

60

70

A-11

3

6

16

72

95

A-9

85

20

7

&

7

69

91

A-8

85

20

7

6

4

67

86

A-6

A-3

85

20

7

6

9

52

90

85

20

7

6

20

51

100

A-7

85

68

7

4

29

40

86

A-16

85

68

7

5

19

40

86

A-11

85

100

7

5

18

54

81

A-8

85

100

7

4

24

58

82

A-13

25

3

9

1.4

25

3

8

4.8

25

55

8

10

25

55

8

5

20

30

7

0.8

89

141

AO

20

30

8

0.5

99

144

A-2

$

14

9

23 23

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little Or no effect

3M Fluorel FLS 2330 (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent U

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist., little or no effect

3M Fluorel (FKM)

recommended ior use (FKM)

rBConmendBdiof use Itttfe/no effect-severe cond, may cause change

<10

3M Fluorel FLS 2330 (FKM) 3M Fluorel (FKM)

Itttte/no effect-severe cond. may cause change <10

8 8

Barium Salts Barium Sulfate

1

8 8

Barium Hydroxide

2.6

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

14

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

42

70

Material Note DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

QQQd-Qxc, xBS\st, mocJer. effect

70

77

Resistance Note

A-16

70

8 aqueous

% Change

(FKM)

recommended: for use

8 aqueous

23

8

<10

Ifttte/ho effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time (0C) Ways) (%)

aqueous

23

PDl Rating

Volume

Tensile Modulus j Elongation Hardness Strength Change

8

Barium Sulfide

a

littte/no effect-severe cond. may cause change

(FKM)

recommended fof use

a

Beet Sugar Liquors 23

8

<10

little/no effect-severe cond. may cause change

2 20

3

Benzaldehyde

3

2

67

A-17

67

ligroine

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

25

3

20

2

8

8

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

3

7

17

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

4

22

52

69

A-14

20

7

6

12

79

93

A-8

20

21

5

15

61

73

A-8

20

21

3

23

45

69

A-16

8

<10

8

Benzene

(FKM)

unsatisfactory for use

1

23

23

recommended for use

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

IRtte/no effect-severe cond, may cause change

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

8

<10

23

7

6

22

25

7

8

7

exc. resist., little or no effect

3M Fluorel FLS 2330 (FKM)

25

7

6

17

good-exe. resist, moder. effect

3M Fluorel (FKM)

25

14

6

22

70

28

4

30

23

51

85

A-17

8

Benzenesulfonic Acid

€

23

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended f of use

<10

littfe/no effect-severe cond. may cause change

8

Benzochloride

(FKM)

recommended f or use

8

Benzoic Acid

8

23

<10

litt(e/no effect-severe cond, may cause change

8

Benzophenone

Benzoyl Chloride

Material Note

recommended for use <10

8

Beer

Resistance Note

70

7

6

100

7

23

10

91

16

A-5

6

12

98

25

A-5

8

<10

8

Benzyl Alcohol 20

56

23

9

1 <10 6

56

8

121

4

8

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent littie/no effect-severe cond. may cause change

little/no effect-severe cond. may cause change

23

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

23

recommended for use

8 8

Benzyl Chloride

8

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

7 8

Benzyl Benzoate

(FKM)

recommended for use

8

70

(FKM)

recommended fof use

littfe/no effect-severe cond. may cause change <10

(FKM)

recommended for use littte/no effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'cn

Reagent

Reagent Note

Cone. Temp. Time

PDL /Havel Dafinrr

{HA

Biobor JF

oil fungicide

6

13

82

83

A-6

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

4

95

92

A-3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

9

1

92

95

A-2

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

70

14

8 8 8 8 8 8 8 8 8 8 8 2 2 2 2 2 1 3

149

7

5

37.5

87.5

68

A-1

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco101XL:TAIC

149

7

4

42.5

86

73

A-7

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoylperox.

149

7

6

42

90

61

A1

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak

5

8 8 8 8

23

solutions

23

solution, sodium borate

23

mixture 23

Boric Acid 23 automotive Delco Girling non-petroleum Wagner 21B 23

Brines Bromine

23 anhydrous 20 anhydrous

23

bromine water

23 25

5

100

5

100

5

Bromine Pentafluoride Bromine Trifluoride 23

Bromobenzene

Material Note

8

lime bleach

hydraulic; BRAKO-Bray Oil Company

Resistance Note

7

solutions

Girling crimson, Lucas lnd.

Hardness

7

Borax

Brake Fluids

Tensile Modulus Elongation Str¬h

2Q

23

Bordeaux

% Retained

Volume

20

Blast Furnace Gas Bleach

% Change

mono bromobenzene 23

8 8 8 8 6 2 2 1 8 8 8

recommended for use little/no effect-severe cond. may cause change

(FKM)

recommended for use fittle/no effect-severe cond. may cause change

(FKM)

recommended lor use littte/no effect-severe cond, may cause change

(FKM)

recommended for use little/no effect-severe cond, may cause change

(FKM)

recommended for use tittle/no effect-severe cond, may cause change

(FKM)

unsatisfactory lor use U

not suitable for service 56

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

tittle/no effect-severe cond. may cause change

(FKM)

recommended iot use 75

100

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent littte/no effect-severe cond. may cause change (FKM) exc. resist., little or no effect 3M Fluorel (FKM)

74

130

A-2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent unsatisfactory for use not suitable for service

(FKM)

recommended for use U

little/ho effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Bromochloromethane

Budium Bunker Fuel C

fuel oil

Cone. Temp. Time {days) ( 0 C) (%) 20

7

2

99

7

8

10

50

7

6

21

60

3

8

3

23 149

40

20

7

Tensile Modulus Elongation Hardness Strength Change

23 40 psi

25

Butane 23 150

Butanediol(1,4-)

28

2-Ethyl

Material Note

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

3M Fluorel (FKM)

8

littte/no effect-severe cond. may cause change

(FKM)

8

exc. resist., little or no effect

3M Fluorel (FKM)

5

minor to moder. effect 15

49

83

A-9

8 3

Resistance Note

A-19

6 monomer

6

16

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent tittle/no effect-severe eond. may cause change

(FKM)

good-exc> resist., moder. effect

3M Fluorel (FKM)

8

recommended fat use

8

littte/no effect-severe cond. may cause change

6

6

82

70

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

recommended for use

8

Butter

2

Butyl Acetate 3

1

230

20

8

1

200

3

1

1

23

Butyl Acetyl Ricinoleate 23 Butyl Acrylate 23 n-butyl acrylate

unsatisfactory for use

20

25

Butyl Alcohol

Volume

27

Butadiene

Butene

PDt Rating

3

50

3

not recommended, substantial effect

a

recommended for use

8

little/no effect-severe cond. may cause change

2

unsatisfactory for use

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM) 3M Fluorel (FKM) (FKM)

not suitable for service

(FKM)

1

190

too soft to test

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1

190

not recommended, substantial effect

3M Fluorel (FKM)

8

butanol

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

not suitable for service 230

1

50

A-24

recommended tor use

8 butanol

23 121

8 4

Butyl Alcohol (tert-) 23 Butyl Benzoate 23 Butyl Butyrate

8

IiHWnO effect-severe cond. may cause change 10

8

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use

8

littte/no effect-severe cond. may cause change

8

recommended for use

4

Butyl Carbitol 8

9

3

70

4

8

8

121

4

7

12

23 Butyl Cellosolve Union Carbide

23

(FKM) (FKM)

moder. to severe effect

20

Butyl Catechol (tert-)

(FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

recommended lor use

8

Ittife/no effect-severe cond. may cause change

2

unsatisfactory lor use

1

not suitable for service

(FKM) (FKM)

(Cont'd.)

Tahle7.1 fOont'rn % Change Reagent

Reagent Note

Cone. Temp. Time PDl (days) Rating (0C) (%)

Volume

% Retained Tensile Modulus! Elongation Hardness Strength Change

2

Butyl Ether 20

Butyl Mercaptan

7

Butyl Mercaptan (tert-) 23 Butyl Oleate 23 Butyl Stearate 23 Butylamine 23 25

3

Butylene 23 Butyraldehyde

9

Resistance Note

unsatisfactory lor use 5

A2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

a

recommended for use

8

iHtte/no effect-severe cond, may cause change

8

recommended for use

8

little/no effect-severe cond, may cause change

8

recommended iof use

8

(Htie/no effect-severe cond. may cause change

2

unsatisfactory fo; use not suitable for service

(FKM) 3M Fluorel (FKM)

8

recommended for use

8

(ittJe/no effect-severe cond. may cause change

2

unsatisfactory lor use not suitable for service mfnor to moder, effect

Calcium Acetate

2

unsatisfactory for use

8

little/no effect-severe cond. may cause change

8

recommended for use

8

Irttle/no effect-severe cond, may cause change

8

recommended for use

23 Calcium Carbonate

(FKM) (FKM)

(FKM) (FKM)

8

Calcium Chloride 23 Calcium Hydroxide 23 Calcium Hypochloride

8

Itttle/no effect-severe cond. may cause change

8

recommended lor use

8

Itttte/no effect-severe cond. may cause change

8

recommended for use

(FKM) (FKM)

8

Calcium Hypochlorite 23 Calcium Nitrate 23

8

littte/no effect-severe iond, may cause change

8

recommended for use

8

little/no effect-severe cond, may cause change

8

Calcium Phosphate Calcium Salts Calcium Silicate

(FKM) (FKM)

recommended f or use

8

H

8

U

8

Calcium Sulfide

8

23

8

Calcium Sulfite

8

Calcium Thiosulfate

little/no effect-severe cond. may cause change

(FKM)

recommended for use K

8

Caliche Liquors Cane Sugar

(FKM)

not recommended, sample disintegrated

1

23

(FKM)

1

6

Calcium Bisulfite

(FKM)

O

Butyric Acid

23

Material Note

liquors

23

Cane Sugar Liquors Caproic Aldehyde 150

Caprolactam Carbamate

23

3

8

littte/ho effect-sever© cond. may cause change

8

recommended for use

2

unsatisfactory f&r use

2

swelled and cracked

8

recommended fof use

8

IrtUe/no affect-severe cond. may cause change

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

minor to mod&r, effect

Carbitol Calgon

23

Carbolic Acid phenol

23

&

may cause si. visible swell/loss of prop,

8

recommended for use

8

trttte/no effect-severe tond. may cause change

(FKM) (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time PDL (days) Baling ( 0 C) (%)

210

7

7

55

80

98

AO

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco 101XL: TAIC

65

210

7

6

36.25

75

110

A-2

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoyl perox.

20

28

8 8

110

A-6

25 25

7

8

23 Carbon Tetrachloride 20 23 23 25 38

7

7 7 180

38 38 38

1095

ro

28

365 730

Carbonic Acid 23 70

7

Catalene 2-ethoxyethanol

20

Union Carbide

23

10

Cellosolve Acetate 20 Union Carbide

hydraulic fluid, triaryl phosphate ester

23 23

8 8 8 8 8 9 9 9 9 7 6 7 8 8 9

7 7

8

(FKM)

minor to moder, effect tittle/no effect-severe cond. may cause change

(FKM)

46

80

76

A3

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak #1

recommended lor use 2

96

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

3

3M Fluorel (FKM)

recommended for use {(ttte/no etfect-severe cond. may cause change 1

85

83

A2

4 2 1 1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent tittle/no effect-severe cond. may cause change

(FKM)

1 2

12

exc, resist,, little or no effect A-4

98

105

92

100

A-3

86

90

A-12

75

86

A-9

85

95

A-6

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use tfttle/no effect-severe pond, may cause change

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3 recommended f or use 40

1 2 3

(FKM)

recommended fof use

8 8

Castor Oil 23 200 24

recommended tor use littte/no effect-severs cond. may cause change

2

28

Carbon Monoxide

Tenneco Chemicals, phosphate esters

Material Note

65

Carbon Disuifide

Cellulube

Resistance Note

7

wet

Castral Hy Spin 55 Catalene Cellosolve

Hardness Change

23 210

dry

Caryophyllin (p-)

Tensile Modulus Elongation Strength

65

23

w/ 35% hydrogen sulfide; @ 500 psig

% Retained

Volume

8 8 6 6 8 5

Carbon Bisulfide Carbon Dioxide

% Change

fittte/no effect-severe cond. may cause change

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

320 unsatisfactory fof use DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

53

mader/severe swell and/or loss of prop,

(FKM)

unsatisfactory for use DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

140

not suitable for service

8

(FKM)

tittle/no effect-severe cond. may cause change

70

7

9

2

70

20

8

7.5

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist, little or no effect

3M Fluorel (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time ("C) Ways) Bating O)

Cellulube 550A

high temp, lube, triaryl phosphate ester high temp, lube, triaryl phosphate ester

20

70 20

20 7

8 9

7.5

24 70

7 7

9 8

2.1

70

7

9.7

205

7

8 8 6

200

3

hexadecane

dry wet dry wet dry

Chlorine

wet dry dry gas

23 23 100 100

5 5

1.3 gm/l

20

30

6.3 gm/l

20 23

30

20 23 25 ao

Chloroacetic Acid

0.02

0.5 30

1 9 5

30

2 1 2' 1 8 2 8 4

7 30

8 8 8 7

23

Chloroacetone 23

Chlorobenzene

mono mono chlorobenzene

20 23 23 23 25

8 8 7 8 2 9

Chlorine Trifluoride

Chloro-p-Toluidine (2-)

0 8 8 8 8 8 8 8 6 8 7

Hardness Change

Resistance Note

Material Note

recommended 1or use 8

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist, little or no effect

2

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc, resist., little o( no effect

3M Fluorel (FKM)

exc. resist., little or no effect

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent 3M Fluorel (FKM)

10

recommended for use 15

81

92

A-12

DuPont Viton B (FKM/TFE); 20 phr MT black 15 phr magnesia or litharge, curing agent recommended far use

6

exc. resist., little or no effect

3M Fluorel (FKM)

recommended for use U

little/no effect-severe cond. may cause change

(FKM)

may cause s i visible swell/loss of prop, exc. resist., little or no effect 81

110

8

8% Cl as NACIO2 in solution

Chlorine Dioxide

Tensile Modulus Elongation Strength

70

Cellutherm 2505A Cetane Chevron M25 Chlordane Chlorinated Solvents

% Retained

Volume

8 a 8

Cellulube 150 Cellulube 220 hydraulic fluid (high viscosity)

% Change

A-3

3M Fluorel (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use

10

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

15 Ifttle/no effect-severe cond. may cause change

(FKM)

unsatisfactory for use O

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

O

not suitable for service

(FKM)

exc. resist, little or no effect

3M Fluorel (FKM)

35

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent unsatisfactory for use not suitable for service

(FKM)

unsatisfactory for use not suitable for service

(FKM)

recommended lor use unsatisfactory for use recommended for use 10

-4 little/no effect-severe cond. may cause change

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

goad-exc. resist, moder. effect

3M Fiuorei (FKM)

8 10

(Cont'd.)

TVihlo 7 1 (C.nnrri \ % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time PDt ( 0 C) Ways) Rating (%)

Chlorobromomethane 23 25

7

minor to moder, effect (FKM)

not recommended, substantial effect

3M Fluorel (FKM)

1 8

7

25

7

Chloronaphthalene (o-) Chloronitroethane

1-chloro 1-nitro ethane 23

Chlorophenol (o-) Chloroprene

chlorobutadiene

tittte/no effect-severe cond. may cause change

8

recommended for use

5

11

7

A-17 littie/no effect-severe cond, may cause change

11

recommended for use

4

moder, to severe effect

1

not suitable for service

8

recommended for use

8

5

2

5

5

7

exc. resist., little or no effect -2 little/no effect-severe cond. may cause change

4

moder. to severe effect

4

52

57

116

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM) 3M Fluorel (FKM)

(FKM) 3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

1

23

exc. resist,, little or no effect

a

2

20

A-13

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

not suitabte for service (FKM)

8

recommended for use

8

tittle/no effect-severe cond. may cause change

8

recommended for use

(FKM)

8

littte/no effect-severe cond. may cause change

(FKM)

8

recommended for use

8

fittte/no effect-sevBre cond. may cause change

8

recommended for use

23

8

littte/no effect-severe cond. may cause change

23

8

M

Chlorotoluene 23 Chrome Alum

8

0.88

8

Chromic Acid 23 Citric Acid 23 Clorox Chlorox Coal Tar Cobalt Chloride

8

-20 23

aqueous solution

recommended for use

-20

Chlorosulfonic Acid

Chromic Oxide

99

8

23

Material Note

litHe/no effect-severe cond. may cause change

8

20

Resistance Note

$

Chlorododecane 23

Tensile Modulus Elongation Hardness Strength Change

&

Chlorobutadiene

Chloroform

Volume

6

2N

(FKM) (FKM)

recommended for use

8 23

Cobaltous Chloride Coconut Oil

8

little/no effect-severe cond. may cause change

8

recommended for use

8

23 100

7

20

7

9 8

Cod Liver Oil

9

7

8

Coffee

8

Coke Oven Gas

8 23

Coolanol 45

Monsanto

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use 4

8

23 25

Coolanol

little/no effect-severe cond. may cause change 0.7

(FKM)

4

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent little/no effect-severe cond. may cause change

(FKM)

exc, resist,, little or no effect

3M Fluorel (FKM)

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use

8

U

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time CC) Ways) (%)

Copper Acetate 23 Copper Chloride 23 Copper Cyanide 23 Copper Salts Copper Sulfate 23

Volume

Tensile Modulus Elongation Hardness Strength Change

Resistance Note

2

unsatisfactory tor use

1

not suitable for service

8

recommended W use

a

littte/ho effect-severe pond, may cause change

8

recommended tor use

8

little/no effect-severe pond, may cause change

8

recommended for use

6

H

8

little/no effect-severe eond. may cause change

10

8

recommended 1or use

50

8

Material Note

(FKM) (FKM) (FKM)

(FKM)

8

Corn Oil 23 Cottonseed Oil 23

8

tittle/no effect-severe cond. may cause change

8

recommended lor use

8

70

28

9

0.3

70

28

8

0.3

149

28

9

1.5

150

28

8

2

89

100

coal tar

8

wood

a

(FKM)

Bxp, resists little or no effect

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc, resist., little or no effect 82

93

(FKM)

tittle/no effect-severe cond. may cause change A-6

A-4

a

Creosols Creosote

PDt Rating

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use U

8 creosote oil

20

coal tar

23

creosote oil

2$

7

Cresol

methyl phenol

7

9

1

100

7

8

10

100

7

6

70

80

A-10

9

70

80

(FKM)

exp, resist* little or no effect

3M Fluorel (FKM)

A-10

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use

23

8

little/no effect-severe cond, may cause change

23

8 28

5

11

81

130

A-11

100

28

7

11

150

28

4

25

68

150

A-15

150

28

3

88

85

A-4

Cumene 23

cutting oil

8

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

a

recommended lor use

8

little/no effect-severe cond. may cause change

a

recommended 1or use

(FKM)

«

8

Cyclohexane

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc, resist»little or no effect

8

Crude Oils

isopropylbenzene

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent little/no effect-severe cond, may cause change

8

100

Cutting Fluids

1

8

Creosylic Acid Cresylic Acid

6

20

7

9

4

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

10

9

0.6

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

23

8

IHtte/ho effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. W

Cyclohexane

Temp. Time 23

7

9

4

25

7

8

4

Cyclohexanone

2

Hardness Change

71

A-32

20

10

1

271

A-33

1

350

Cyclopentanone

20

7 5

20 10

Cymene (p-) isopropyltoluene

23

silicons oil, Dow Corning

175

28

177

28

Dupont

1

272

A-30

1

280

A-32

8

recommended lor use

8

little/no effect-severe cond. may cause change

9

-2

9

-2.3

23 70

7

solutions

A2

1

100

photo 23

Developing Solutions Dextron Diacetone

23 Diacetone Alcohol 23 Diazinon Dibenzyl Ether 23 Dibenzyl Sebacate 23 Dibromoethylbenzene 23 Dibutyl Ether 23 Dibutyl Phthalate DBP

20

10

23 DBP

recommended for use

8

ifttte/no effect-severe cond. may cause change

121

8

76

8

24

A-18 recommended for use ftttte/no effect-severe cond. may cause change

3

5

80

96

A-1 recommended for use littte/no effect-severe cond. may cause change

S

recommended fpr use

2

unsatisfactory for use

1

not suitable for service

2

unsatisfactory for use

1

not suitable for service

€

minor to rnoder. effect

2

unsatisfactory for use

1

not suitable for service

6

minor to moder. effect

€

may cause si. visible swell/loss of prop,

8

recommended for use

6

may cause si. visible swell/loss of prop,

4

moder, to sever? effect

4

modet ./severe swell and/or loss of prop,

6

minor to moder. effect

?

31 modef/severe swell and/or loss of prop. 20

(FKM)

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

A

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

S

3M Fluorel (FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

8 30

(FKM)

recommended for use

8 2

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist* little or no effect

8 23

with bleach solution

9

3M Fluorel (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Itttle/no effect-severe cond. may cause change 7

Decane Delco Supreme Il

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Jittte/no effect-severe cond. may cause change

23 70

3M Fluorel (FKM)

not recommended, substantial effect

8

€

Decalin

«XQ. re$f$t.f little or no effect unsatisfactory for use

1

25

Material Note

recommended for use

5

23

Resistance Note

(FKM)

20

Cyclohexyl Alcohol

Developing Fluids

Tensile Modulus Elongation Strength

Ways)

Cyclohexanol

Detergents

% Retained

Volume

(0C)

8

DC 200

% Change PDt Rating

(FKM)

(FKM) (FKM)

(FKM) (FKM) (FKM) (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time PDl (%) CC) (days) Rating

% Change

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Change

20

8

14

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent may cause si. visible swell/loss of prop.

6

23 70

4

7

18

121

4

7

20

Dibutylamine 23

Dichloroaniline (3,4-)

7

20

30

20

3

Dichlorobenzene (o-)

unsatisfactory for use

1

not suitable for service

recommendediof use A-8

8

little/no effect-severe cond. may cause change

8

23 25

3

8

8

70

28

8

10

70

28

7

10

149

28

6

25

150

28

5

25

exc, resist, little or no effect 77

105

A-12

83

120

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM) 3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

good-exc. resist,, mocfer, effect A-15

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended fo* use

8

Dichlorobenzene (p-)

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

35

8 7

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2 5

Material Note

mfttor to moder, effect

6

Dibutyl Sebacate

Resistance Note

a 8

Dichlorobutane Dichloroethylene

£0

7

Dichloroisopropyl Ether 23

Dicyclohexylamine 23

Diesel Fuels

diesel oil

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-19

16

4

moder. to severe effect

4

modern/severe swell and/or loss of prop,

2

unsatisfactory for use

1

not suitable for service

8

recommended for use

8

23 diesel oil; Shell Rotella T 15W40

5

little/no effect-severe cond. may cause change

(FKM) (FKM) (FKM)

150

7

6

0.3

68

68

A1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

7

7

0.6

69

84

A-3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

7

7

0.3

63

80

A-4

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

42

&

0.3

56

54

AO

150

42

6

0.6

60

61

A-5

42

. 6

62

49

A2

8

Diethyl Benzene

8

23 70

7

. 23

Diethyl Sebacate 23

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended fw use ((ttte/no affect-sever&eorMt may cause cftanga

8 2

Diethyl Ether

1

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

6

unsatisfactory fof use

i &

not surtabte for service

6

may cause si. visible swell/loss of prop,

(FKM)

mtnorto moder. effect (FKM)

(Cont'd.)

Table 7.1 (Cont'cn % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time PDl Ways) Rating CC) (%)

Diethylamine 23 Diethylene Glycol

recommended 1or use little/no effect-severs cond. may cause change

7

6

29

10

1

175

7

9

Diisooctyl Sebacate

good-exc. resist,, moder. effect

Diisopropylidene Acetone

23

1

not suitable for service

23

1

23

7

Dimethyl Phthalate 20

10

Itttte/no effect-severe cond. may cause change

6

mtnor to moder. elfect

8

8 may cause si. visible swell/loss of prop.

7

1

142

23

50

A-33

1

138

22

46

A-29

20

10

7

15

110

5

4

(FKM)

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

unsatisfactory lor use

1

not suitable for service

2

unsatisfactory for use 50

(FKM)

7

1 1

not suitable for service

(FKM)

7

1

not recommended, substantial effect

3M Fluorel (FKM)

23

Dinitrotoluene 23 77

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

28

25

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

20

20

60

A-40

20

Dimethylformamide

with 40% monotoluene

19

30

23

DNT

11

6

Dimethylaniline

DMF

350

5

121

Dimethylformamide (N,N-)

1

6

23

xylidine

minor to moder. elfect

unsatisfactory lor use

methyl ether, monomethyl ether

DMT

6

2

50

DMSO

little/no effect-severe cond, may cause change recommended ior use

DMAC

3M Fluorel (FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

S

tittle/no effect'severe cond. may cause change

Diisopropyl Ketone

(FKM)

recommended tor use AO

0.8

8

23

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

a

Diisopropyl Benzene

Material Note

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

29

a

23

Dimethyl Terephthalate

8

25

20

Dimethyl Sulfoxide

not suitable for service

20

Diisobutylene

Dimethyl Ether

unsatisfactory for use

1

6

Diisobutyl Ketone

Resistance Note

2

7

20

Tensile Modulus Elongation Hardness Strength Change

a

23 Difluoroethylene

Dimethyl Acetamide (N1N-)

Volume

11

too soft to test

2

unsatisfactory for use

1

not suitable for service 375

Dioctyl Phthalate 23 Dioctyl Sebacate

6

minor to moder. effect

e

may cause sL visible swell/loss of prop,

6

minor to moder. effect

6

23

7

11

14

1

94

14

9

9

149

3

149 150

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

65

3

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(FKM)

may cause s). visible swell/loss of prop,

(FKM)

exc, resist,, little or no effect

3M Fluorel (FKM)

not recommended, substantial effect 97

94

A-4

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time PDL Ways) Bating (%)

Volume

H)

Tensile Modulus Elongation Hardness Strength Change

2

Dioxane

unsatisfactory lot use

7

2

128

34

59

A-17

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

4

52

106

185

A-19

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

25

1 3

Dioxolane 23 Dipentene 23 Diphenyl 23

biphenyl/phenylbenzene Diphenyl Oxide

1

100

not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

2

unsatisfactory for use

1

not suftabte for service

6

recommended fof use

8

(ittte/no affect-severe con
8

recommended for use

8

littWno effect-severe cond. may cause change

8

recommended fo* use

8

tittle/no effect-severe cond. may cause change

Dow Corning 11

8

recommended for use

Dow Corning 200

8

Dow Corning 220

8

23

diphenyl ether

Dow Corning 33

8

Dow Corning 4

8

Dow Corning 5

8

Dow Corning 510

8

Dow Corning 55

8

a

Dow Corning 550

8

H

8

M

Dow Corning 710 Dowtherm

oil 23

fluids, Dow Chemical

8

H

8

little/no effect-severe cond. may causa change

2

unsatisfactory for 059

solution

50

with water

50

125

7

6

40

50

125

14

4

65

with 46% water

good-exc. resist., moder. effect

54

98

3

6

12

60

74

A-1

54

98

12.5

2

31

17

14

A16

54

98

12.5

3

27

17

9

A18

20

28

9

24

28

9

2.5

100

28

7

7

8

7.3

exc. resist., little or no effect

22

good-exc. resist, moder, effect

DP 47

A-1

87

95

A-8

28 28

205

28

3

100

40

9

O

exc. resist., little or no effect

149

40

O

U

40

9

0.5

23 DV 4709

204

7

(FKM) 3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

22

51

180

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1QO

199

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc, resist,, little or no effect

204

Dry Cleaning Fluids

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Dowtherm A

heat transfer fluid

(FKM)

recommended for use

8

heat transfer fluid

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Dowtherm 209

heat transfer fluid

Material Note

20

23 Dioxane (1,4-)

Resistance Note

A-14

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent 3M Fluorel (FKM)

8

recommended 1or use

8

little/no effect-severe cond. may cause change

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

1

340

(Cont'd.)

Table 7.1 (Cont'd.) % Change Reagent

Reagent Note

121

Elco L 14374

ElcoM2C105A

ElcoM2C108A

ElcoM2C111A

ElcoM2C119A

Engine Oils

Cone. Temp. Time PDl (days) Rating ("C) (%)

engine coolant; Mack truck

Modulus Elongation Strength

Hardness Change

7

5

2

60

46

21

1

72

30

A5

3

78

21

A11

2

78

19

A12

1

83

84

A2

1

67

48

A2

2

90

47

A5

2

94

47

A10

1

90

84

A1

1

78

74

AO

2

75

47

A5

2

95

42

A10

3

59

47

A2

3

58

37

A7

4

65

45

A6

5

69

37

A11 A5

121 150 150 121 121 150 150 121 121 150 150 121 121 150 150 121 121 150 150 82

17.8

5 5 5 8 6 6 € 8 7 6 6 5 4 5 4 5 6 4 4 8

82

17.8

8

7 21 7 21 7 21 7 21 7 21 7 21 7 21 7 21 7 21

Resistance Note

Material Note DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A3

1

55

58

2

81

47

A7

4

55

21

A11

4

49

32

A11

3

85

118

A-1

2

83

102

A-4

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Engine EOG-1

175

3

8

1

85

85

A-4

Engine EOG-2

175 175 175 175 175 177 177 177 177 177 177

3

1

93

90

A-2

1

75

75

A-2

1

81

73

A-2

0.8

88

86

A-2

1

93

101

A-3

7

9 7 7 8 9 9 9 9 9 9 9 2 1 1 1

150

7

2 4

3.1

62

64

A-2.5

showed cracking/crazing

3M Fluorel (FKM); 66 wgt.% fluorine; Shore A75

150

7

7

2.8

88.4

85

A-0.5

no cracking or crazing

3M (FKM/TFE); high fluoride (70 wgt.%) peroxide cured; Shore A76

150

7

3

1.4

43

38

A-2

showed cracklrtgfcrazing

150

7

5

1.6

84

35

A-2

Engine EOG-3 Engine EOG-4 Engine EOG-5 Engine EOG-6 EOG-1 EOG-2 EOG-3 EOG-4 EOG-5 EOG-6

3 3 3 3 7 7 7 7 7 7

Epichlorohydrin 23 50 50

Epoxy EP Gear Lubricants

% Retained

Volume

7

resins factory fill mineral oil base

new thermally stable mineral oil base

1

exe. resist, little or no effect

1.1

U

1.2

H

3M Fluorel (FKM)

1.2 0.8 1 unsatisfactory for use 94

not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

94

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent unsatisfactory for use

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

EP Gear Lubricants

Reagent Note

new thermally stable mineral oil base new thermally stable synthetic base

ESEL Fuel No. 20

Cone. Temp. Time PDL {days) Bating ( 0 C) (%1 150

7

4

1.5

52.5

27

A3.5

7

3

1.2

31

30

A3

150

7

3

8

47.3

38

AO.5

15Q

7

3

1.4

48

28

A1

150

7

3

4.6

38.8

33

A-3

150

7

5

1.6

25

7

9

1

23 Ethanol mono ethanolamine

Ethers Ethyl Acetate

Tensile Modulus I Elongation Hardness Strength | Change

150

Ethane

Ethanolamine

Volume

Material Note

showed cracking/crazing

3M Fluorel (FKM); 66 wgt.% fluorine; Shore A75

3M (FKM/TFE); high fluoride (70 wgt.%) peroxide cured; Shore A76

A-3 exc. resist, little or no effect

8

recommended lor use

8

littleVno effect-severe cond, may cause change

4

moder* to severe effect

6

minor to moder, effect

2

unsatisfactory fqr use

4

moder. to severe effect

3M Fluorel (FKM) (FKM)

unsatisfactory for use

organic ester 20

1

1

A280

1

23 23

7

too soft to test not suitable for service

1

280

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

25

7

1

375

not recommended, substantial effect

3M Fluorel (FKM)

55

7

6

17

good-exc. resist., moder. effect

3M Fluorel FLS 2330 (FKM)

20

7

2

Ethyl Acetoacetate

1

unsatisfactory tor use 168

1

23

A-33 86

65

1

55

7

1

20

7

9

2

A2

20

28

7

6

A-10

A230

1

23

230

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent not suitable for service

(FKM)

not fecommended, substantial effect

3M Fluorel (FKM)

recommended for use

8

Ethyl Alcohol

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

23

4

moder/severe swell and/or loss of prop,

23

1

not suitable for service

23

7

8

6

25

7

9

2

Ethyl Benzene 23 Ethyl Benzoate 23 Ethyl Bromide Ethyl Cellosolve 23

Ethyl Cellulose 23 Ethyl Chloride 23

(FKM)

unsatisfactory tor use

7

20

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent not suitable for service

2

Ethyl Acrylate

Union Carbide

Resistance Note

exc. resist, little or no effect

8

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use

8

little/no effect-severe cond, may cause change

8

recommended for use

2

unsatisfactory for use

1

not suitable for service

2

unsatisfactory lor use

1

not suitable for service

8

recommended ior use little/no effect-severe cond, may cause change

8 97

(FKM)

3M Fluorel (FKM) (FKM) (FKM)

(FKM) (FKM) (FKM)

100

(Cont'd.)

Table 7.1 (Cont'd.) % Change Reagent

Reagent Note

Cone. Temp. Time f°C1i Idavst

Ethyl Chlorocarbonate 23 Ethyl Chloroformate 23 Ethyl Ether 20

3

3

Ethyl Formate 23 37

Ethyl Hexanol Formaldehyde (2-) Ethyl Hexyl Alcohol Ethyl Mercaptan

25

Volume

% Retained Tensile Modulus Elongation Hardness Chano© Strenoth

7

23 Ethyl Oxalate 23 Ethyl Pentachlorobenzene 23 Ethyl Silicate 23 Ethylcyclopentane

Resistance Note

8

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use

1

not suitatjfe for service

2

unsatisfactory lor use

5

97

1

97

Material Note

(FKM) (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-3

1

23 24

PDt Rating

not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

8

recommended for use

8

little/no effect-severe cond. may cause change

(FKM)

exc. resists IiHIe or no effect

3M Fluorel (FKM)

9

1

8

recommended for use

6

minor to moder. effect

6

may cause si. visible swell/loss of prop,

8

recommended iof use

8

little/no effect-severe cond. may cause change

8

recommended fQf use

8

little/no effect-severe cond. may cause change

8

recommended lor use

8

little/no effect-severe cond. may cause change

8

recommended for use

(FKM) (FKM) (FKM) (FKM)

8

Ethylene

8

23 25

gas, 800 psi

3

Ethylene Chloride 23 Ethylene Chlorohydrin 23 Ethylene Dibromide Ethylene Dichloride 23 25

7

Ethylene Glycol 23 100 with water with 50% distilled water

14

7

26

minor to moder. effect may cause si. visible swell/loss of prop,

8

recommended for use

8

tittfe/no effect-severe cond. may cause change

8

recommended for use H

little/no effect-severe cond. may cause change

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

7

16

8

recommended for use

8

little/no effect-severe cond, may cause change

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

9

2

3

9

0.8

7

7

7.5

50

100

28

8

4

80

97

50

116

30

6

3

68

87

A8

50

116

30

6

4

67

87

A7

50

150

28

7

8

74

94

Ethylene Trichloride 23

(FKM)

8

100

5

(FKM)

8

10Q

70

3M Fluorel (FKM)

6

50

23

(FKM)

exc resist., little or no effect

6

50

Ethylene Oxide

little/no effect-severe cond. may cause change

3M Fluorel FLS 2330 (FKM) good-exc. resist., moder. effect

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

unsatisfactory for use

1

not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

1

230

8

recommended for use

8

little/no effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 fCont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time PDl (days) Rating (%) (0C)

Ethylenediamine 23

Ethylhexyl Alcohol (2-)

Ethylmorpholine Stannous Octoate ET 387

2-ethylhexanol

with 50% stannous octoate

Volume

unsatisfactory for use

1

not suitably for service

7

3

>50

100

5

$

6

121

5

8

8

9

3

F 60

149

28

9

0.1

F 61

149

28

9

0.7

23 Ferric Chloride aqueous

23 14

Ferric Nitrate 23

aqueous Ferric Sulfate

23

aqueous

92

95

Fish Oil

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

AO exc. resist., little or no effect

8

recommended for use

a

little/no effecVsevere eond. may cause change

8

recommended for use

$

349

4

20

(FKM) 3M Fiuorel (FKM)

recommended for use (rttla/no effect-severe cond. may cause change

8

recommended for use

8

Ifflte/no effect-severe cond. may cause change

8

recommended for use

23

8

20

6

itttte/no effect-severe cond. may cause change 113

120

liquid 23

Fluorobenzene 23 Fluorolube Fluorosilicone

minor to moder. effect

6

may cause si. visible swell/loss of prop,

8

recommended for use

8

tittle/no effect-severe cond, may cause change

6

minor to moder. effect may cause si. visible swell/loss of prop,

€

Occidental Chemical

23 70

7

9

0.6

A-4

70

7

9

1

A-4

FS-1281, Dow Corning

Fluothane

6

FS-1280, Dow Corning

8

2$

Fluosilicic Acid 2-bromo, 2-chloro 1,1,1trifluoroethane

1

2

75

24

1

2

75

not recommended, substantial effect

20

7

8

not suitable for service 0.7

110

116

4 Formic Acid

23

(FKM) (FKM) (FKM)

(FKM)

3M Fiuorel (FKM)

unsatisfactory lor use

1

23 37

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2 Formaldehyde

(FKM)

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent little/no effect-severe cond. may cause change

20

(FKM)

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

6.9 Fluorine

(FKM)

not recommended, substantial effect

8

Fluoboric Acid

3M Fiuorel (FKM)

littte/no effect-severe cond. may cause change

8

Fish Oils

(FKM)

unsatisfactory lor use

7

Fatty Acids

Material Note

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2 205

lubricant, Dow, high temperature

Resistance Note

2 23

50

Tensile i Modulus Elongation Hardness Strength Change

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-2

moder. to severe effect

4

modef./savere swell and/or loss of prop,

(FKM)

not recommended, substantial effect

3M Fiuorel (FKM)

70

7

2

70

7

2

20

21

5

22

70

84

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

21

4

18

61

73

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

28

4

34

61

77

83

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use

8

Freon 11

A-18

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time Idavst

Freon 11 with Suniso 3G

50

with 50% Sunsiso 3G

50

23 24 149 150

7

28

8 8 6 5

7

23

Freon 113 20

20

7

6 6 e 6 6 4

20

7

5

20

7

6 6 7

23 24

7

20

28

23 25

27

Freon 114 23

Freon 114B2 Dupont

23

Freon 115 chloropentafluoroethane

Freon 12 23 24 149 160 with 50% ASTM oil no. 2

50

with ASTM Oil No. 2

50

with Suniso 4G

50

with 50% Sunsiso 4G

50

93 93 149 150

28 7 7

28

8 6 8 5

23

Freon 13B1 bromotrifluoromethane

20 23 24

28

20

7

24

7

Freon 14 tetrafluoromethane

Freon 142B Freon 152 A Freon 152B

Dupont

23

Dupont

23

€ 6 6 4

7

7 7

Freon 13 Dupont

6 6 6 5

6 6 6 4

7

Volume

Tensile

Modulus Elongation

6 6 8

18

Resistance Note

Material Note

may cause si. visible swell/loss of prop,

(FKM)

good-exc. resist., moder. effect

3M Fluorel (FKM)

16 DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

16 recommended for use little/no affect-severe cond. may cause change

(FKM)

minor to moder. effect 18

38

75

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-6

15

may cause si. visible swell/loss of prop,

(FKM)

good-exc. resist., moder. effect

3M Fluorel (FKM)

minor to moder. effect may cause si. visible swell/loss of prop,

(FKM)

minor to moder. effect 11

46

50

A-3

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

11

75

62

A-5

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent may cause si. visible swell/loss of prop,

(FKM)

minor to moder. effect DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

16

16

may cause si, visible swell/loss of prop,

(FKM)

good-exc. resist., moder. effect

3M Fluorel (FKM)

minor to moder, effect 21

46

75

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-6

21

may cause si. visible swell/loss of prop,

(FKM)

good-exc. resist., moder. effect

3M Fluorel (FKM)

20 20

36

75

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-11

25 good-exc. resist, moder. effect

25

3M Fluorel (FKM)

17 17

30

75

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-12 recommended for use may cause sJ. visible swell/loss of prop,

(FKM)

recommended: for use 19

46

75

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-6

19

may cause si. visible swell/loss of prop.

(FKM)

goQQ^exc, resist., moder, effect

3M Fluorel (FKM)

recommended f of use 0.6

9 2 1 2 1

Hardness Phanf№

Qafinn 6 € 6 7

28

Freon112 Dupont

PDl

0.6

95

98

A2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist, little or no effect unsatisfactory for use

3M Fluorel (FKM)

not suitable for service unsatisfactory for use

(FKM)

not suitable for service (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time P D l (days) Rating ( 0 C) (%)

Hardness Change

Resistance Note

Material Note

14

20

14

2

80

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

20

2

90

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

21

20

21

2 2

77 84

Freon 218 23

Freon 22

23 24 liquid

93

Frigen 22; vapor

180 1SO

20 7 14 14

unsatisfactory Io r use not suitable for service

(FKM)

recommended foruse little/no effect-severe cond. may cause change

(FKM)

unsatisfactory for use

80

DuPont Viton B (FKM/TFE); 20 phr MT black 15 phr magnesia or litharge, curing agent

31 37

54 54

A-15 A-19

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1 2 5

90 32

4

50

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3

60

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

32

50

not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Dupont

23

Dupont

23

liquid

20

14

5 2 1 2 1 6 2

20

14

4

Dupont

23

vapor

180

14

6 €

28

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

180

14

S

36

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

7

8 8 8 3 7

with ASTM Oil No. 2

50

93

7

Freon 31 Freon 32 Freon 502

Freon BF Freon C316 Freon C318

Tensile Modulus Elongation Strength

20

23

liquid

% Retained

Volume

2 1 8 8 2 2

Freon 21

Dupont

% Change

tetrachlorodifluoroethane

23

Dupont

23

Dupont

20 23

Freon MF Dupont

23

Dupont

23

Dupont

23

Freon TA Freon TC

6 6 e 4 4 8 8

good-exc. resist., moder. effect unsatisfactory for use

3M Fluorel (FKM)

not suitable for service unsatisfactory for use

(FKM)

not suitable for service mtoof to moder, effect

66

(FKM) DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

may cause si. visible swell/loss of prop,

(FKM)

recommended for use tittle/no effect-severe cond. may cause change

(FKM)

recommended for use

16

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent may cause si. visible swell/loss of prop, minor to moder. effect

(FKM)

may cause si. visible swell/loss of prop, moder. to severe effect

(FKM)

moder./severe swell and/or loss of prop, recommended for use

(FKM)

IttSe/no effect-severe cond, may cause change (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time f°CH

PDL Ways) Rating

Hardness Change

Resistance Note

Material Note

150

40

HEF-2, high energy, trialkyl pentaborane

135

3

3

HTF1 experimental high temperature

288

3

3

28

8 8 2 1 1

86

21

53

A-38

121

28 28

4 1

86 120

20

43

A-38

20

2

2 9

0.6

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

10

1

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

£0

56

70

10

Freon TMC Dupont

Freon TP35 Dupont

23 23

Freon TWD602 Dupont

23

20

Shell #6

149

acidic 23

Fumaric Acid 2$

Furfural furfuraldehyde

23 70 70

Furfuraldehyde Furfuryl Alcohol

Fyrquel Fyrquel 150

Tensile Modulus Elongation Strength

Bunker C, 6000 second fluid oil

£3

Fuels

% Retained

Volume

6 6 8 8 8 8 8 8 8 8 8 8 8 a

Freon TF

FR Fluid Fuel Oils

% Change

Stauffer Chemical

MIL-G-23652, type Il

(FKM)

recommended for use tittle/no effecteBvere cond, may cause change

(FKM)

recommended for use little/no effect-sevBre cond. may cause change

(FKM)

recommended for use

5

little/no effect-severe pond, may cause change

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

recommended for use M

little/no effect-severe cond, may cause change 87

96

A-3

11

65

9

A24

17

31

310

A-9

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

a

recommended 1cr use littte/no effect-severe cond, may cause change

(FKM)

unsatisfactory to* use not suitable for service

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

good-exc. resist,, moder, etteet

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

unsatisfactory 1or use

3

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

58

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

7

8 8 8

13

94

106

A-3

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

7

8

5

96

118

A-1

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

7

8

3

88

86

A-3

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1OO

3

8 8

4

89

105

A-4

1QO

3

8

10

89

94

A-6

100

3 3

7 8

7 4

95

128

86

89

A-1 A-1

23

Fyrquel 220 MIL-G-23652, type I

9

minor to moder. effect may cause si. visible swell/loss of prop,

100

little/no effect-severe cond. may causa change

(FKM)

recommended to* use

recommended tor use DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Fyrquel GT

Cone. Temp. Time PDt (0C) Ways) Ratino (%)

Hardness Chanoe

Resistance Note

Material Note

7

6

14

good-exc. resist., motfer. effect

3M Fluorel (FKM)

7

S

3

exc. resist., little or no effect

3M Fluorel FLS 2330 (FKM)

30

9

good-exc resist matter, effect

3M Fluorel (FKM)

100

Esso Golden

Tensile Modulus Elongation Strength

100

30

Gasoline

% Retained

Volume

100 too

Gallic Acid

% Change

23

O 19

8

recommended for use

S

little/no effect-severe cond. may cause change

8

recommended for use

(FKM)

$

super Shell

8 M 15 fuel

20

3

7

7

80

100

A-10

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

antioxidant no. 22

20

7

9

1

96

95

AO

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

automotive fuel 2B

20

28

7

automotive fuel 60

20

28

7

13

automotive fuel 6OB

20

28

30

automotive fuel RF2

20

28

6 9

Esso golden

20

28

a

4

A-6

Shell super

20

28

2

A-5

automotive fuel 2B

20

50

9 7 7 $ 8

automotive fuel 60

20

50

automotive fuel 6OB

£0

50

automotive fuel RF2

20

50

liquefied, LPG

23

a

producer

23

8

23

Gasoline

unleaded

23

7

24

7

24

7

a

16

5

17 15 30 9 !ittte/nG etfset-severe cond.rosycause change a 5

W

44

98.75

73

A-1

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco 101XL: TAIC

60

100

72

A-1

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoylperox.

42

70

80

A2

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak #1

$ & unleaded

24

7 5

automotive fuel 6OB

24

28

30

good-exc. resist., motor, effect

Esso golden

24

28

&

4

exc. resist.. little or no effect

Shell super

24

28

a

2.3

automotive fuel 6OB

24

30

30

automotive fuel 2B

25

28

automotive fuel 60

2$

28

automotive fuel RF2

25

28

automotive fuel 2B

25

50

automotive fuel 60

25

50

6 6 7 8 6 7

automotive fuel RF2

25

50

a

9

premium 51% arom.,0 .1 wt% antiox. no.22

43

3

8

premium w/26% arom. content, 2.47 g/gal regular

43

3

43

3

premium 51% arom.,0 .1 wt% antiox. no.22

43

7

9 7

(FKM)

3M Fluorel (FKM)

good*8xc resist., moder. effect

16

U

13

me. resist., little or no effect

5 17

good+exc resist* moder. effect

15

exc. resist., little or no effect

5

94

100

A-8

2

99

100

A-7

2

101

100

A-6

8

88

90

A-11

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Cone. Temp. Time PDt Ways) Rating (0C) (%)

% Change

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Change

Reagent

Reagent Note

Gasoline

premium w/26% arom. content, 2.47 g/gal

43

7

9

4

98

98

A-8

regular

43

7

3

98

95

A-11

Gasoline Additive Gear Lubricants

Gear Oils

lead, 2.03 mg/l antioxidant no. 22

43

14

8 6

6

101

100

A-10

premium 51% arom.,0 .1 wt% antiox. no.22

43

14

8

12

101

100

A-13

9 5

5

101

100

A-7

14

57

76

A-8

8 4

23

55

81

A-25

regular

43

14

M 15 fuel

54

7

Texaco Premium

60

2

M 15 fuel

65

3

gasoline antioxidant #22

24

7

GL-4A

149

3

GL-4B

149

3

lead soap-active sulfur

149

3

MIL-L-2105

149

3

SCL, sulfur-chlorine-lead

149

3

GL-4A

150

3

GL-4B

15Q

3

lead soap-active

150

3

sulfur MIL-L-2105, 15% additive meeting

150

3

SCL, sulfur-chlorine-lead

150

3

HD 90

175

7

GE 81406

177

7

HD 90

177

7

149

7

149

21

150

7

Texaco 3450

Texaco 3450, rear axle oil

150 21

Gelatin Gelatins Girling Crimson Glaubers Salt

£3 70 14 23

Glucose 23

Glues 23

Glycerin

glycerol glycerin

glycerol

20

2

20

28

20 23

56

7

Resistance Note

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

3M Fluorel (FKM) DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resists little or no effect

3M Fluorel (FKM)

9 9 9 9 9 9 9

1.3

2

96

99

AO

9 9 9

1

96

98

A1

1

99

100

AO

1

93

97

AO

9 5

2

91

99

A-1

4

60

60

A-6

9 7 6 8 7 9

O

exc. resist., iittle or no effect

3.7

good-exc. resist,, moder, ettect

9.1

exc, resist, iittle or no effect

6 8 8 2 6 8 8 8 8 8 8 9 9 9 8

Material Note

2 1 1 1 1.6 DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent 3M Fluorel (FKM)

recommended for use 3M Fluorel (FKM)

26 9

26

56

95

100

A2

78

86

A-7

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use little/no effect-severe eond. may cause change

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

minor to moder, effect ttttle/no effect-severe cond. may cause change

(FKM)

recommended for use littte/no effect-severe cond. may cause change

(FKM)

recommended for use Itttte/no effect-severe cond. may cause change

(FKM)

recommended fot use -0.4

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

0 -0.5 Ifttte/ho efleci-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Cone. Temp. Time PDt /0Ct O&*in ft

Volume

Reagent

Reagent Note

Glycerin

glycerin

70

2

9

-0.6

U

70

28

9

-0.4

70

56

9

-0.1

121

5

9

1

Glycols 23 Greases

recommended lor use

light grease

8

Shell Alvania #2

8 100

21

9

A-2

magnet

100

21

9

2

A-2

100

21

9

2

A-2

Shell Air GG-1034 WTR

175

3

6

13

85

133

A-6

Supermil ASU-06752, American Oil Co.

175

3

6

19

66

87

A-5

Shell Air GG-1034 WTR

175

7

7

17

90

80

A-1

Supermil ASU-06752, American Oil Co.

175

7

4

32

39

40

A2

Halowax Oil

lubricant; Ucon 50HB280X, Union Carbide

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

recommended for use

8

(Mla/no affect-severe cond. may cause change

8

recommended for use

8

U

(FKM)

(FKM)

8

23 175

7

7

8

205

14

9

3

76

105

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-4 A2

tittle/no effect-severe cond. may cause change

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

Helium

8

N-Heptane vinyl plasticizer, Hercules

150

14

4

13

66

133

A-11

150

14

6

17

76

100

A-14

recommended for use

N-Hexaldehyde n-Hexaldehyde

Hexane

1

swallow

Hanover MIL-H-83282

(FKM)

8

machine oil no. 120

Halothane

Hexaldehyde

B

Ifttle/no effect-severe cond. may cause change

23

Hercoflex 600

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use

8

Koppers

Material Note

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

Green Sulfate Liquor

Heptane

Resistance Note

Keystone #87HX

Sunoco; all purpose

Heat Transfer Fluids

Tensile Modulus Elongation Hardness Strength PHjinnA

23

N-Hexane-1

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

unsatisfactory for use

1

no! suitable for service

8

recommended for use

(FKM)

8 n-Hexane

20

21

Hexene Hexyl Acetate

8

1

23

7

9

1

n-Hexane

25

21

9

1

n-Hexene-1

23 5

20

10

1 1

little/no effect-sever© cond. may cause change

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

little/no effect-severe cond. may cause change

a

20

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-10

8

23

290

A-30

308

A-26

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time PDt Ways) Rating ( 0 C) (%)

Hexyl Alcohol 23 1-hexanol

HEF 2

70

7

135

3

high energy fuel

Houghto Safe 271

water & glycol base

Houghto Safe 620 HS 1010 HS 1055 HS 1120

water & glycol base

70

HS 5040 HS 620 HTF

experimental high temperature fuel

HyTran17 Hydraulic Fluids

14

70

7

1OO

14

8 4 6 6 6 6 6 7 6 9 7 3

% Retained

Volume

Tensile M&dultIS Elongation Strength

Hardness Change

recommended for use 11

not recommended, substantial eifecf

14

good-exc. resist^ moder. effect

3M Fluorel (FKM)

minor to moder. effect good-exc- resist^ mader. effect

13

3M Fluorel (FKM)

20

14 14

70

14

70

14

288

3

288

3

70

7

6 8

2 5

9.1 20 1.7

exc. resists little or no effect

7.9

good-exc. resist., moder, effect

17

31

310

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-9

17

good-exCv resist., moder. effect

3M Fluorel (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

38

1095

Shell Iris 902, water-inoil emulsion

66

28

9

Bray Oil 762

70

7

7

Cellulube, triaryl phosphate ester

70

7

9

2

CHX-604

70

7

8

3

FR fluid 20

70 70

7 7

8 7

13

Houghto-Safe 1120, phosphate ester base

70

14

8

9

A-5

Houghto-Safe 62, EF Houghton

70

14

7

8

A-9 A-1

recommended for use 64

86

A-7

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-2 84

107

78

94

80

106

A-3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-2

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

AO

2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Shell Tellus 33, petroleum base

70

28

9

0.6

Univis J-43, petroleum base, Exxon Mine Fluid 3XF, Shell, fire resistant

70

28

9

2

90

21

8

0.7

105

105

1QO

3

8

7

100

112

A-3

100

3

8

3

92

95

A-3

100

3

9

2

92

100

A-5

100

3

6

14

82

94

A-18

100

3

6

16

76

121

A-6

Houghto-Safe 520, water glycol base

3M Fluorel (FKM)

minor to moder. effect

Oronite 8200, disiloxane, high temp.

Houghto-Safe 1120, phosphate ester base

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

6

8 8 6

Houghto-Safe 1010, phosphate ester base

Material Note

recommended for use

70

Sunsafe; fire resistant

Resistance Note

little/no effect-severe cond. may cause change

100

Univis 40

Hydraulic Fluids

8 8 8

% Change

AO A-9

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

{Cont'd.)

Table 7.1 (Cont'd.)

Reagent Hydraulic Fluids

Reagent Note

% Change

% Retained

volume

Tensile Modulus Elongation Strength

Hardness Change

Resistance Note

Material Note

Houghto-Safe 520, water glycol base

100

3

7

9

89

129

A-2

Houghto-Safe 1120, phosphate ester base

1OO

7

8

8

97

118

A-1

100

7

B

4

94

116

A-3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

7

9

2

94

106

A-5

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

7

5

21

57

89

A-10

100

7

5

33

50

95

A-8

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

7

6

22

63

118

A-4

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Houghto-Safe 1055,phosphate ester base

100

14

7

20

A-5

Houghto-Safe 1120, phosphate ester base

1QO

14

6

20

A-12

Hydro-Drive MIH-50, high viscosity

100

14

9

0.3

DP 47, ICI, silicone base, fire resist.

100

40

9

O

121

180

&

15

66

105

135 149 150

7

9 8 9

3

89

100

A-1

93

100

AO

264

7

22

A-54

177

14

41

A-56

Houghto-Safe 520, water glycol base

Univis J-43, petroleum base, Exxon BP Aero no. 1

Hydraulic Fluids

Cone. Temp. Time PDl CC) Ways) Rating <%J

Oronite 8200, disiloxane, high temp.

40 7

1 1

A-2 100

100

AO

exc. resist, iittle o( no effect

3.2 2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150 150

7

Oronite Hyjet

150 150

7

15

53

A-56

7

1 1

159

Oronite Hyjet W

243

10

24

A-53

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Houghto-Safe 1120, phosphate ester base

150

14

6

7

88

150

A-6

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Houghton Vital 29 FM

150 150

14

6

6

88

140

A-8

20

a

5

150 150

40

3

75

108

A-2

40

8 9

O

95

100

AO

Shell F.R.phospate ester/Aroclor mixture BP Aero no. 1 DP 47, ICI, silicone base, fire resist. Shell Aeroshell Fluid No. 4 Oronite 8200, disiloxane, high temp.

7

A-5

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

40

8

3

75

108

A-2

175

3

8

2

85

80

A2

175

3

8

2

93

79

A3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Oronite 8515, 85%; 8200/15% high temp.

175

3

6

5

72

85

A-10

Univis J-43, petroleum base, Exxon

175

7

8

4

87

89

A-1

Oronite 8200, disiloxane, high temp.

175

21

9

2

A-1 A-2 A6

Oronite 8515, 85%; 8200/15% high temp.

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

175

21

9

4

175

28

5

-8

too brittle to test

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Hydraulic Fluids

Hydraulic Fluids

Reagent Note

% Retained

Volume

Tensile MOdtllttS Elongation Strength

Hardness Change

Resistance Note

Material Note

Versilube F-50, silicone base, GE

175

28

9

3

A2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

175

41.6

5

5

29

44

A2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

175 175

83 83

3 3

6

27 26

6 11

A13

4

Houghto-Safe1120, phosphate ester base

200

14

6

12

86

Houghton Vital 29 FM

200 205

14 3

6 9

12

63

2

205

3

9

1

Oronite 8200, disiloxane, high temp.

A16

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

140

A-9

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-11

96

100 97

105

100

A2 A-2

A-3

Oronite 8515, 85%; 8200/15% high temp.

205

3

7

4

72

85

Oronite 8200, disiloxane, high temp.

205

7

6

1

50

58

A1

Oronite 8515, 85%; 8200/15% high temp.

205

7

6

5

70

61

A1

206

7

7

4

80

68

A-1

205 205

21 21

7

43 40

29 30

AO

8

Oronite 8200, disiloxane, high temp.

205

28

Versilube F-50, silicone base, GE

260

3

100

14

62

a 4

A13

a

-3

A8

9

1

A-2

5

8

PRL-high temperature

a

petroleum base

Brayco 783, MIL-H-6083 PQ-1307, MIL-H-6083

30 30

23 $Q

7

8 8

60 30 70

7 7 5

8

Hydrazine 23 Hydro-Drive MIH 10

petroleum base

Hydro-Drive MIH 50

petroleum base

100 100

14 14

Hydrobromic Acid 23 40 40

23

saturated 3 molar concentrated miriatic acid, concentrated

20

30

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A3

2

petroleum base

Avrex 903, MIL-H-6083

Hydrocarbons Hydrochloric Acid

% Change

Oronite 8200, disiloxane, high temp.

Hydro-Drive MIH-10, low viscosity

Hydraulic Oils

Cone. Temp. Time PDt (0C) Ways) Rating W

toofrrHtlato test

recommended for use H

Irttle/no effect-severe cond. may cause chaoge 0.6

82

108

A1

0.4

84 85

100 100

A3

0.5 14

A3 A-7

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

7 2 1 8 9 8 9 8 8 8 8 a 8 8 8

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

unsatisfactory 1of use not suitable for service

(FKM)

recommended for use 1

exc, resist, little or no effect

3M Fluorel (FKM)

recommended Iqr use exc, resist., IiWIe or no effect

0.3

3M Fluorel (FKM)

recommended for use littte/no effect-severe cond. may cause change

(FKM)

recommended for USB littte/no effect-severe cond. may cause change

(FKM)

recommended for use M

3

A5

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Hydrochloric Acid

Reagent Note

Cone. Temp. Time POl Ways) Rating (%) ( , C)

Tensile MOdUlUS Elongation Strength |

20

30

7

14

concentrated

23 70

7

9

<5

cold

37

hot

37

cold

37

hot

37

muriatic acid

U

2

70

2.916 7

5

38

70

2.916 7

38

70

2.916 7

47

20

47

20

7

47

38

180

7

47

38

365

7

730

6

38 70 70

1095

7

7

3

47

70 70

7

4

3

47

70

7

8

6

70

70 70

7 7

7 7

3

70

5

70

70

7

8

4

3

S 8 1 8 4 €

47 47 47

7 3

7

3

48 48

20

7

48

20 20

21

hot, concentrated anhydrous

48

& 8

A-7

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(FKM) 103

117

little/no effect-severe cond. may cause change

(FKM)

exc. resist., little or no effect

3

3M Fluorel (FKM) 3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

118.75

87

A-14

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco 101XL: TAIC

4

52.5

114

63

A-7

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoyl perox.

5

50

110

63

A-8

100

108

A3

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak #1 DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

78

114

A2

75

107

AO

79

122

A-2

75

142

A-9

86

120

A-7

72

200

A-10

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

84

105

A-2

75

108

A-3

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent «

85

118

A-6

94

110

A-4

&

1

2

&

9 2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

9

9

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton GH; 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use Kttte/no effect-severe cond. may cause change

(FKM)

not suitable tor service littls/no effect-severe cond. may cause change

U

moder./severe swell and/or loss of prop, good-exc. resist., moder. effect

22 1

7

21

2

69

3

23 23 23 23 25 20

cold, concentrated

Material Note

may cause $J, visible sweft/loss of prop,

Hydrocyanic Acid anhydrous

Resistance Note

recommended lor use

38

47

Hardness Change

8 8 8

37

47 U

14

23 23 25 70

37

Hydrofluoric Acid

% Retained

Volume

miriatic acid, concentrated miriatic acid, concentrated

Hydrochloric Acid

% Change

3M Fluorel (FKM)

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

0.7

AO

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

A-2

2

A-4

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cnnt'J}

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Hydrofluoric Acid

Cone. Temp. Time PDt (days) Rating ( 0 C) (%)

Tensile Modulus Elongation Strength

48

25

7

7

12

23

7

9

2

Resistance Note

Material Note

exe, resist., little or no effect

3M Fluorel (FKM) (FKM)

<65

8

recommended for use moder. to severe effect

hot

<65

4

cold

>65

3

recommended for use

hot

>65

4

moder, to severe effect

75

70

5

5

81

150

A-9

75

100

5

3

60

150

A-13

gas, cold gas, hot 53

gas anhydrous

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

a

recommended for use

8

iKtle/no effect-severe cond, may cause change

8

recommended for use

8

U

8

tittle/no effect-severe cond. may cause change

2

unsatisfactory for use

19

2.1

9

20

4.1

5

82

20

4.1

9

100

24

7

9

2

in water 40

6 90% active

Hydrogen Peroxide

90

20

90

23

90

132

7

9

A-2

95

A-1

0

2 2

wet, cold

2

recommended for use 3M Fluorel (FKM)

minor to moder. effect 0

106

102

AO

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent may cause si, visible swell/loss of prop,

2

dry, hot

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist., little or no effect

6 0.08

dry, cold

58

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

unsatisfactory 1or use

2

wet, hot wet, cold

23

1

wet, hot

23

1

gas @ 2.0 MPa (300 psi) w/65% carbon dioxide; @ 500 psig

254

6

90

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

liquid, anhydrous

gaseous

Hydrogen Sulfide

Hardness Change

cold

23

Hydrogen Fluoride

% Retained

Volume

50

Hydrofluosilicic Acid Hydrogen

% Change

132 35

35

35

210

210

210

7 7

7

7

not suitable for service

(FKM)

6

50

95

A-9

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

5

46

80

76

A3

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak #1

7

55

80

98

AO

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco101XL:TAIC

6

36.25

75

110

A-2

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoyl perox.

100

3

7

7

90

137

A-1

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

3

9

4

98

106

A-5

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

3

?

6

95

135

A-2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

7

6

11

95

135

A-6

Hydrolubric120B

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time PDL o Ways) Rating (%) (

Hydrolubric120B

C)

6

92

111

A-5

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1Q0

7

€

12

83

126

A-1

DuPont Viton B (FKM/TFE); 20 phr MT black 15 phr magnesia or litharge, curing agent

Hypochlorous Acid 23

2

unsatisfactory for use

8

recommended for use

8

little/no effect-severe cond. may cause change

21

8

2

149

14

7

3

70

7

g

0.8

2

unsatisfactory ior use

1

not suitable for service

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

8

4.7

150

60

7

21

106

88

A4

150

120

6

25

107

79

A11

8

25

8

21

8

lsobutyl N-Butyrate

8

lsododecane

8

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use

1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

^ 23

1 A11

tittle/no effect-severe cond. may cause change

(FKM)

good-exc, resist,, moder, effect

3M Fluorel (FKM)

recommended for use

8

lsooctane 20

21

25

21

2

9

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1

2 1

ketone 23 with isophthalonyl chloride

9 8

23

lsophthalic Acid

DuPont Viton B (FKM/TFE); 20 phr MT black 15 phr magnesia or litharge, curing agent

28

21

3M Fluorel (FKM)

recommended for use

66

20

(FKM)

recommended ior use good-exc, resist., moder, effect

8

lsobutyl Alcohol

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

23

lsophorone

2

138

Iodine Pentafluoride

Shell

little/no effec^severe cond. may cause change

9

Univolt 35, Exxon

lsoamyl Alcohol

unsatisfactory for use

a

4.2

Iodine

Iris 902

2

180

Swan Finch

Insulating Oils

Material Note

7

Hydyne

Hypoid SAE 90

Resistance Note

7

23

Veedol

Tensile Modulus Elongation Hardness Strength Change

100

Hydroquinone

Hypoid Oil

Volume

100

4

20

7

7

AO

23 lsopropyl Alcohol

1

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

unsatisfactory for use not suitable for service

17

2

lsopropyl Acetate

little/no effect-severe cond. may cause change

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

unsatisfactory for use 290

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1

not suitable for service

8

recommended for use

(FKM)

8 isopropanol

23

lsopropyl Chloride 23 lsopropyl Ether Catalene B

20

little/no effect-severe cond. may cause change

8

recommended: for use

8

little/no effect-severe cond. may cause change

Z

unsatisfactory for use

1

23 lsopropyl Nitrate

8

7

1

not suitable for service 320

(FKM) (FKM) (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Jet Aircraft Engine Oils

DV-4709, thermally stable

Jet Aircraft Fuels

% Change

% Retained

Volume

Tensile Modulus Elongation Strength

340 1

A-1 A-2

20 20

28

9

1.7

JP 4

24

28

9

1.6

JP 5

24

28

9

1.3

JP 6

38

3

8

4.2

JP-6

38

180

9

38

365

9

38

730

8

JP 4

O

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist., little or no effect

100

95

100

95

AO

87

93

A-6

Material Note

3M Fluorel (FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A3

38

1095

6

73

86

A-7

175

3

7

13

96

91

A-10

175

3

7

8

92

117

A-5

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

175

3

9

5

99

102

A-5

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

175

14.6

7

17

75

100

A-7

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

175

14.6

4

23

63

63

A-8

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

175

41.6

5

17

89

160

A-8

175

41.6

3

20

45

160

A-14

175

83

4

26

57

79

A-10

175

83

3

39

40

40

A-7

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

200

3

7

23

79

100

200

7

3

14

67

170

A-19

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

200

7

7

8

A-3

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

200

14

6

23

204

3

7

12

exc. resist, little or no effect

7

4

gootf-exc, resist, mocter. effect

204

3

205

3

JP-4

205

3

8

12

JP 5

260 269

3

5

5.8

3

3

6

JP 5

Resistance Note

A-60

1 9

JP 5

Jet Aircraft Fuels

50

7

JP-4

Stauffer 7700

7

Hardness Change

205

28

Stauffer Jet II, MIL-L23699B

Jet Aircraft Oils

Cone. Temp. Time PDl tfays) Rating (0C) (%)

78

105

75

104

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent 3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

4 85

100

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-3

A32

not recommended, substantial effect

3M Fluorel (FKM)

too brittle to test

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc resist., little or no effect

3M Fluorel (FKM)

JP 6

288

3

7

18

JP-6

288

3

3

18

25

325

A-12

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

Turbo no. 10, petroleum base, Exxon

70

3

0.4

96

115

A-2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Turbo no. 65, petroleum base, Exxon

70

3

O

92

106

AO

Turbo no. P-16, petroleum base, Exxon

70

3

2

79

121

AO

0.3

94

121

A2

Turbo no. 10, petroleum base, Exxon

70

7

7 8

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Jet Aircraft Oils

Reagent Note

Cone. Temp. Time PDL (days) Rating ( 0 C) (%) 70

Turbo no. 65, petroleum base, Exxon

7

% Retained

Volume

Tensile Modulus Elongation Strength

8

0

92

118

77

Hardness Change

Turbo no. P-16, petroleum base, Exxon

70

7

7

127

A2

Mobil II, MIL-L-23699

150

21

6

11

74

81

A-1

200

14

3

26

29

44

A-15

200

14

5

16

61

82

A-10

205

3

6

14

71

79

AO

205

3

7

17

77

95

A-4

205

14.6

3

23

26

57

A-16

205

14.6

4

19

26

47

A-7

205

41.6

29

17

A5

205

41.6

5 4

38

7

A-12

23

8 7

9

70

7

9

0

28

7

20

2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent littie/no effect-severe cond. may cause change

(FKM)

exc. resist, little or no effect

3M Fluorel (FKM)

unsatisfactory lor use

2 20 lacquer solvents

28

1

23

1

23

1

cold

8

hot

8

cold

23

8

hot

23

8

85

158

7

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent not suitable for service 81

recommended for use little/no effect-severe cond. may cause change

7

8

Lavender Oil 23

Lead Acetate 23

Lead Suifamate 23 DTE petroleum ether of benzene benzine/nitrobenzine

(FKM)

45

21

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-30 recommended for use

8

Light Oil Ligroin

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

149

Lacquer Thinners Lacquers

Material Note

recommended for use

8 23

Resistance Note

A2

2

Kerosine

Lactic Acid

% Change

11

8

little/no effect-severe cond. may cause change

2

unsatisfactory for use

1

not suitable for service

S

recommended for use

8

little/no effect-severe cond. may cause change

a

recommended for use

(FKM) (FKM) (FKM)

8

38

(Htte/no effect-severe cond. may cause change

8

23 28

8

2

8

Lime Bleach Lime Sulfur 23

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended Io ruse

8

14

8

little/no effect-severe cond. may cause change

(FKM)

100

79

A-1

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Lindol

Reagent Note

Cone. Temp. Time PDl ( 0 C) tfays) Rating <%?

hydraulic fluid; phosphate ester type hydraulic fluids, Stauffer Chemical

23

9 9 9

121

7

8 8 8 8 7

3

U4; high viscosity

Shell Spirax HD; rear axle lube Royco 808-RH, Royal Lubricants

ET 387, Dow, high temperature

Pentalube TP-653, Heyden-Newport

Lubricating Oils

minor to rnoder. effect may cause si. visible swell/loss of prop,

(FKM)

recommended: lor use little/no effect-severe cond. may cause change O

(FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

O O 1

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use H

good-exc. resist., moder. effect

3M Fluorel (FKM)

3

8

6

87

100

AO

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3

9

3

98

105

AO

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

7

8

1

81

104

A-4

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

14

6

2

67

71

AO

205

3

5

23

59

115

A-15

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

205

3

5

18

50

100

A-20

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

205

7

9

3

92

95

AO

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20$

7

9

3

92

95

AO

DuPont Viton B; 20 phr MT black, 15 phr magnesia or litharge, curing agent

205

7

5

21

69

96

A-22

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

SAE 30

8 6 8 a 8

SAE 40

a

SAE 10 SAE 20

23 150 150

solutions

23

Magnesium Chloride 23

recommended tor use

3

8 8 7

-1

108

70

A-3

3

7

-2

81

77

A-2

SAE 50 Sun XSC 71 367

(FKM)

150

di-ester

petroleum base

Material Note

150

petroleum base

Lye

minor to moder. effect may cause si. visible swell/loss of prop,

28 56 7

H2; high viscosity

Resistance Note

€

70 70 121 LPG

Hardness Change

6

2

Linseed Oil

Shell Spirax EP90

Tensile Modulus Elongation Strength

23 70

23

Elco M2G105B; rear axle lube Sunoco X5 820 EP Lube

% Retained

Volume

6 6 8 8 9

Linoleic Acid

Liquid Petroleum Gas Liquimoly Lubricants

% Change

6 € 8 8

littte/no e|fecl+severe<mnd- may cause change

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

minor to moder. effect may cause sk visible swell/toss of prop,

(FKM)

recommended lor use litrte/no effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time PDL Ways) Rating ( 0 C) (%)

Magnesium Hydroxide 23 Magnesium Salts

% Change

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Change

Resistance Note

8

recommended for use

a

littte/no effect-severe cond. may cause change

8

recommended iat use

8

little/no effect-severe cond. may causa change

Magnesium Sulfite

a

recommended for use

Malathion

8

23

23 Maleic Anhydride 23 Malic Acid 23 Mercuric Chloride vapors

Mercury Chloride

littte/nc- effect-aevere cond. may cause change

a

recommended for use

1

not suitable for service

a

recommended for use

8

(fttte/no eWect-aevere cond. may cause change

a

recommended Iw use H

23

8

[Rtte/ho effect-severe cond. may cause change

ZZ

a 2

unsatisfactory lor use

ZZ

i

nol suitable for service

23

1

$0

3

e

$ A180 7

(FKM)

(FKM)

exc, resist,, little or no effect

3M Fluorel (FKM)

may cause si. visible swell/loss of prop,

(FKM)

too soft to fest

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

not surtabte for service

(FKM)

1 i

Methyl Acetoacetate

(FKM)

unsatisfactory fQf use

20 ZZ

(FKM)

recommended lot use 0.3

2

Methyl Acetate

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

26

a 3

gas, 500 psi 23

unsatisfactory fof use

2

Methyl Acrylate

2

20 ZZ

7

Methyl Acrylic Acid

Methyl Alcohol

8

8 a

ketone

Methacrylic Acid

Methane

(FKM)

8

Maleic Acid

Mesityl Oxide

(FKM)

a

Magnesium Suifate

Mercury

Material Note

too soft to test

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1

not suitable for service

(FKM)

4

moder. to sever© effect

ZZ

1

50

S

methanol

3

A210

1

26

20 20

methanol

7 7

unsatisfactory fof use

6

39

75

91

A-6

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

22

51

165

A-27

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

75

105

A-2

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

4

42

20

7

8

3

not suitable for service

1

23 23

7

25

7

(FKM) 3M Fluorel (FKM)

recommended far use

a 2

commercial grade

not suitable for service good-exe. resist., mocEer, eifeci

(FKM)

4 1

150

not recommended, substantial effect 3M Fluorel (FKM)

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time Ways) (0C) (%)

Methyl Alcohol with 50% isooctane

50

PDt Rating

25

7

7

6

60

1

4

42

Methyl Benzoate

3

Methyl Bromide

8

Methyl Butyl Ketone 23 Methyl Carbonate Methyl Cellosolve Union Carbide

23

Methyl Cellulose Methyl Chloride 23 Methyl Chloroformate 23 Methyl D-Bromide

Resistance Note

Material Note

good-exc. resist., motfer. effect

3M Fluorel FLS 2330 (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use

2

unsatisfactory lor use

1

not suitable for service

8

recommended lor use

2

unsatisfactory for use

1

not suitable for service

2

unsatisfactory tor use

8

recommended for use

6

may cause si. visible swell/loss of prop,

8

recommended for use

6

may cause si. visible swell/loss of prop,

8

recommended for use

dimethyl ether/monomethyl ether

23

8

methyl ether

23

8

little/no effect-severe cond. may cause change

2

MEK

MEK

(FKM)

(FKM)

(FKM)

unsatisfactory for use

7

1

458

A-51

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

1

313

A-43

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent not suitable for service

(FKM)

6

good-exc. resist., moder. effect

3M Fluorel FLS 2330 (FKM)

290

not recommended, substantial effect

3M Fluorel (FKM)

1

23 23

7

1

25

7

7

25

7

1

240

unsatisfactory for use

2 2

MIBK 80

8

20

7

1

214

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent unsatisfactory for use

2 Methyl lsopropyl Ketone MBK Methyl Methacrylate

23 20

3

23 Methyl Oleate Methylaniline

(FKM)

20

Methyl Ethyl Ketone Peroxide

1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

200

1

not suitable for service

2

unsatisfactory for use

1

too brittle to test

1

not suitable for service

8

recommended for use

23

6

may cause si visible s we it/lass of prop.

23

6

M

grease

150

40

8

0.7

110

109

A4

grease, oxidation inhib.

150

40

8

17

89

99

A3

fluid

205

40

7

4

119

90

A7

fluid, oxidation inhib.

205

40

8

4

112

85

A-3

Methylene Blue

20

4.8

Z

swelled ami cracked

Methylene Bromide

23

8

(fttte/no eJfect-severe cond. may cause change

Methylchlorophenyl Silicone

(FKM)

8

Methyl Ether

Methyl lsobutyl Ketone

Tensile Modulus Elongation Hardness Strength Change

8

Methyl Cyclopentane

Methyl Ethyl Ketone

Volume

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM) (FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time (days) (0C) (%)

mfrtof to moder, effect

2G

7

5

20

56

109

A-19

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

4

16

45

57

A-10

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

6

may cause si. visible swell/Joss of prop,

(FKM)

25

3

4

27

not recommended, substantial effect

3M Fluorel (FKM)

25

3

6

15

good-exc. resist., moder, eifec!

38

28

3

29

31

60

A18

50

7

48

37

90

A-33

3 4

40

7

-5

116

82

A5

38

180

9

0.1

100

105

A2

38

365

9

0.3

90

90

A1

38

730

9

0.3

97

110

A-6

64

88

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

38

1095

6

1

175

4

4

34

A-20

175

4

5

22

A-16

205

4

6

25

A-8

205

4

3

34

A-22

70

28

8

121

14

3

6

92

120

A-2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

121

14

8

4

103

130

A-2

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

recommended for use

135

7

8

exc. resist., little or no effect

8

recommended for use

Milk Mine Fluid 3XF

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent moder. to severe effect

205

oil

3M Fluorel FLS 2330 (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

minor to moder. effect

oil

Mil-O-5606

Material Note

25

fluid

Mil-L-23699

Resistance Note

6

monomethyl hydrazine

Mil-L-2104-B

Mineral Oils

Modulus Elongation Hardness Change

6

Methylformamide

Mil-R-83282

Strength

7

Methylene Dichloride

Mil-8200

Tensile

ao

23

Methylphenylsilicone

Volume

6

Methylene Chloride

Methylhydrazine

PDt Rating

Univolt #35

A-10 DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

3M Fluorel (FKM)

3M Fluorel (FKM)

8 8

23 100

Mobil XRM 206A

MIL-H-83282

Mobile JET Il Motor Oils

Esso Super Permalube 10W30 Synthetic, SOC-100, SAE 10W40

7

9

100

7

9

121

180

8

175

7

175

3

tittle/no effect-severe pond, may cause change 106

105

103

96

2

89

108

8

2

82

84

7

13

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

AO exc. resist., little or no effect

8

3M Fluorel (FKM)

recommended for use

149

7

8

0.5

150

3

7

2

good-exc. resist., motfer. effect 82

71

A1

3M Fluorel (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Motor Oils

Reagent Note

% Change

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Change

Esso, 2OW 50

150

7

6

0.8

66

Shell super, with STP oil additive

150

7

8

2

150

7

6

2

150

7

6

3

57

67

A1

150

7

9

4

91

100

A-1 A1

Spirax 90 EP, with STP oil additive

Resistance Note

Material Note

68

A-5

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

74

96

A-1

45

62

AO

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Synthetic, SOC-100, SAE 10W40

150

7

7

2

74

70

Shell super, with STP oil additive

150

14

7

1

73

71

AO

150

14

5

1

43

48

A1

150

14

6

2

58

76

A-1

150

14

9

3

93

100

A-1

150

14.6

7

1

63

79

A1

150

14.6

6

1

58

71

A-2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Esso, 2OW 50

150

28

5

0.8

55

56

A-3

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

American LDO , SAE 10W-30

150

125

5

2

47

63

A11

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

125

4

2

43

57

A14

10W40 SG CD

163

0.083

7

88

no cocking Qf crazing

163 163

0.17 0.17

3 9

72 97

showed cracking/crazing

163 163

0.33 0.33

8 3

163

0.67

163 163

1 1

Spirax 90 EP, with STP oil additive

American LDO , SAE 10W-30

Motor Oils

Cone. Temp. Time PDL Ways) Rating (0C) (%)

U

10W30 SG CC

10W30SGCD

10W30 SG CE

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent 3M Fluorel (FKM); 66 wgt.% fluorine; Shore A75

no cracking or crazing

3M (FKM/TFE); high fluoride (70 wgt.%) peroxide cured; Shore A76

92 60

showed cracking/crazing

3M Fluorel (FKM); 66 wgt.% fluorine; Shore A75

Z

60

no cracking or crazing

3M (FKM/TFE); high fluoride (70 wgt.%) peroxide cured; Shore A76

Z 2

55 52

showed cracking/crazing

44 48

163 163

2 2

2 2

163 163 163 163

7 7 7 7

a

2.2

4 4 3

1.7

163 163 163 163

7 7 7 7

3 3 4 6 .

0.6

163

7

4

94 69.4 44 43.1

82 60 52 47

2.6

36.8 29.4 53.3 88.3

42 25 59 70

2.9

59.2

55

1.8 1.9

1.1 1.8

3M Fluorel (FKM); 66 wgt.% fluorine; Shore A75 3M (FKM/TFE); high fluoride (70 wgt.%) peroxide cured; Shore A76 A-2

no cracking or crazing

A-1.5

showed cracking/crazing

A-1.5 AO.5

3M Fluorel (FKM); 66 wgt.% fluorine; Shore A75

A1.5 A2.5 A-0.5 A-1.5 A-2.5

» no cracking or crazing

3M (FKM/TFE); high fluoride (70 wgt.%) peroxide cured; Shore A76

showed cracking/crazing

(Cont'd.)

Table 7.1 (Cont'd.)

% Retained

% Change Reagent

Motor Oils

Reagent Note

Cone. Temp. Time PDl Ways) Rating CC) (%)

Tensile Modulus Elongation Hardness Strength Change

Resistance Note

Material Note

showed cracking/crazing

3M Fluorel (FKM); 66 wgt.% fluorine; Shore A75

3M (FKM/TFE); high fluoride (70 wgt.%) peroxide cured; Shore A76

10W30SGCE

163

7

3

1.6

35.1

33

A2.5

10W40SGCD

163

7

3

0.8

42.5

46

A0.5

163

7

3

1.1

32

26

A8

163

7

8

1.1

98

80

A-1.5

no cracking or crazing

163

7

3

2.2

49.1

42

A0.5

showed cracking/crazing no cracking or crazing

15W40SGCE

Synthetic, SOC-100, SAE 10W40

163

7

9

0.9

94.8

91

A-1.5

163

7

8

1.2

92.5

84

A-2.5

163

7

4

2.7

57.7

56

A-2.5

163

7

3

1.8

42.1

48

A3.5

17$

3

6

3

74

57

A1

175

7

5

4

20

7

8

Naphtha

23

Naphthalenic Acid

9

showed cracking/crazing

recommended lor use DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent 67

25

7

8

4

70

28

8

7

70

28

7

7

52

A3

little/no effect-severe cond. may cause change

(FKM)

exc, resist,, little or no effect

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

recommended for use

23

8

littte/no effect-severe cond. may cause change

23

8

Naphthenic Acids

8

Natural Gas

8 23

Neats Foot Oil 23 Neon

3M Fluorel (FKM); 66 wgt.% fluorine; Shore A75 DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

4

8

Naphthalene

94

113

(FKM)

A-11 recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use

(FKM) (FKM)

8

Neville Acid 23 Nickel Acetate aqueous

23

Nickel Chloride aqueous

23

Nickel Salts

8

little/no effect-severe cond. may cause change

2

unsatisfactory for use

1

not suitable for service

8

recommended lor use

8

tittle/no effect-severe cond, may cause change

8

recommended lor use

(FKM) (FKM) (FKM)

a

Nickel S u If ate aqueous

23

Niter Cake

8

little/no effect-severe cond. may cause change

8

recommended fox use

3

little/no effect-severe cond. may cause change

3 molar

a

recommended for use

concentrated

3

dilute

8

23 Nitric Acid

Volume

inhibited red fuming; IRFNA

6

minor to moder effect

red fuming; RFNA

4

mode*, to severe effect

red fuming

20

inhibited, red fuming

23

7

6 1

23

(FKM) (FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent not suitable for service

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Nitric Acid

Reagent Note

Cone. Temp. Time PDl CC) Ways) Dating (%) 7

6

23

7 7

4 3

60 60

10 10

66 66

28 28

4 5

41 41

0-50 60

23 20

7

6 9

4

60

24

7

8

4.4

70

20

3

9

0.5

70

20

3

9

0.5

70

20

7

$

2

Hardness Change

Resistance Note

Material Note

good-exc. resist., motfer. etfect

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

good-exc. resist., mocter, effect little/no effect-severe cond. may cause change

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc, resist., little or no effect

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

102

119

A2

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

70

20

7

9

4

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

70

36

180

2

22

11

475

A-24

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

70 70 70

38 70 70

365 3 3

1 2 9

38 28 5

2

510

A-35

38

375

A-35

56

A-27

49

216 405

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

70 70

70 70

7 7

2 2

21 15

70

70

7

4

12

45

138

A-10

70 70

70 70

7 14

3 2

8 8

49

165 345

A-20

35

70

70

14

4

9

79

253

A-14

90

as

7

6

22

50100

23

4

e 20 23 23

10

7

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-25

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-23

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent good-exc. resist,, motor, effect

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

moderisevere $Well and/or lass of prop-

(FKM)

mtnartomoder. effect

15 may cause si visible swell/loss of prop,

&

23 20

1

2 t 2 8 8 1

190

25

1

1

190

23 textroxide N2O4,1

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

24

7

Nitroethane

Nitrogen Dioxide

Tensile Modulus Elongation Strength

70 70

Nitrobenzene

Nitrogen

% Retained

Volume

24

red fuming

Nitric Acid

% Change

unsatisfactory for use not suitable For service

(FKM)

unsatisfactory for use recommended for use little/no effect-severe cond. may cause change

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

not recommended, substantial effect

3M Fluorel (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

% Change Reagent

Reagent Note

Cone. Temp. Time Ways) CC) (%)

PDl Baling

23

1

Nitrogen Tetraoxide

25

1

20

Nitrogen Tetroxide Nitromethane

23

7

Nitropropane

Nitrotoluene

with 60% dinitrotoluene

10 23

Octadecane 23 N-Octane n-Octane

23

Octyl Alcohol 20

35

23

Oil Additive

Z$

35

Parapoid 10-C, Enjay Chemical

150

3

Oleic Acid 23

Oleum

60

2.5

fuming sulfuric acid spirits fuming sulfuric acid

Olive Oil

1

280

Resistance Note

Material Note

not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorel (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

unsatisfactory lor use

1

not suitable for service

2

unsatisfactory for use 130

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended lor use

6 8

little/no effect-severe cond. may cause change

8

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended fw use

8

little/no effect-severe cond. may cause change

8

recommended for use

9

0.7

(FKM) (FKM) (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

little/no effect-severe cond. may cause cftange

(FKM)

exc- resist, little or no effect

3M Fluorel (FKM)

O

sampte disintegrated

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

tmot to moder. eifecf

6

may catt$$ sL visible swell/loss <sf prop,

(FKM)

2

swelled and cracked

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

S

recommended for use

1

8 23 20

7

23

8

littte/no effect-severe cond. may cause change

8

recommendedtotuse

9

4

25

7

as

3

8

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

4

exc. resist., little or no effect

3M Fluorel (FKM)

2.2

exc. resist., little or no effect

recommended <0f use

£0

7

8

3

177

21

&

1.5

177

28

6

0.5 1

not recommended, substantial effect

204

3

204

7

8

3

«

204

14

5

3

204

28

6

1.6

not recommended, substantial effect «

177

3

9

0

exc. resist., little or no effect

177

21

7

3.6

good-exc. resist., moder. effect

177

28

6

-0.8

not recommended, substantial effect

204

3

8

4

exc. resist., little or no effect

8

Oronite 8515

(FKM)

little/no effect-severe cond. may cause change

6 6

Oronite 8200

% Retained Tensile Modulus Elongation Hardness Strength Change

2

8

n-Octanol

Olein

100

8

40

Octachlorotoluene

Octane

1

1

20

Volume

exc. resist., little or no affect 3M Fluorel (FKM)

recommended for use

3M Fluorel (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Oronite M2V

Orthochloroethylbenzene Orthochloronaphthalene Orthodichlorobenzene OS 124

OS 45

n-Bis(mphenoxyphenoxy), Monsanto OS 45 type III Monsanto type IV hydraulic fluid

Monsanto type IV hydraulic fluid

Monsanto, type III hydraulic fluid Monsanto type IV hydraulic fluid

7

4

85

114

A-7

€

8

60

92

A-12

205

7

8 8 8 5

260

7

175

21

3 8 a

3

53

7

A22

6.9

3

3

204

7

a

205

3

205

7

205

7

205

7

205

21

205

21

260

3

260

3

cold cold

23

hot

23

cold

93-149 23 20

40

23

Palmitic Acid 23 149

3

23

Pentalube TP653

A-2

177

2Q4

7

8 8 8 5 5 6 9 8 8 8 8 8 8 2 8 6 6 8 8 6 8 6 8 8 8 8 8 €

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

recommended tot use -13

204

Material Note

recommended for use

O

8 8

Resistance Note

littte/no effect-severe cond. may cause change 2

21

Ozone

ParapoidiOC Peanut Oil

Hardness Change

7

OS 45 type IV

Ouco Kearsley, XyIoI base, Kearsley Varnish

Tensile Modulus Elongation Strength

7

liquid

Paint Thinners

% Retained

Volume

200

23

Oxygen

% Change

200

23

Monsanto, type III hydraulic fluid

OS 45-1 OS 70 Oxalic Acid

Cone. Temp. Time P D l CC) Ways) Rating (%)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use 9

A-3 exc. resist, littte or no effect

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent 3M Fluorel (FKM)

6

6

80

91

AO

3

82

85

A-1

3

75

98

A-2

11

62

67

A-3

4

56

48

A4

4

67

54

AO

9

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-1

9

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist,, little or no effect

3M Fluorel (FKM)

recommended for use << iHUe/no effect-severe cond. may cause change

(FKM)

recommended for use unsatisfactory lor use (tttte/no effect-severe cond. may cause change

(FKM)

may cause si. visible swell/loss of prop, mmor to moder. effect recommended (or use little/no effect-severe cond, may cause change

(FKM)

minor to moder effect 4

A-6

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent may cause si. visible stfelMoss of prop,

(FKM)

recommended foi use 9

Ifttfe/no effect-severe cond. may cause change

(FKM)

exc, resist,, IiHIe or no effect

3M Fluorel (FKM)

recommended for use 21

tittle/no effect-severe cond, may cause change

(FKM)

good-exc. rests)., moder. effect

3M Fluorel (FKM)

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time PQL ttays) Rating (0C) (%)

Volume

Tensile Modulus Elongation Hardness Strength Change

20

7

8 1

220

19

30

A-34

Pentoxone

20

7

1

284

13

18

A-37

Perchloric Acid 23 Perchloroethylene 20

7

23

Perchloryl Fluoride Petroleum

7

8

recommended for use

little/no effect-severe cond. may cause change

9

1 1

exc. resist., little or no effect

7

9

38

180

8

92

81

38

365

0

98

100

A-3

38

730

7

92

93

A-9

38

1095

6

5

87

95

A-7

70

3

8

9

86

108

A-2

70

3

7

9

82

108

A-3

70

13.9

7

9

82

108

A-6

70

13.9

7

8

88

108

A-5

8

8

87

100

A-9

89

105

A-9

70

28

1QO

28

7

11

20

7

2

73

A-2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

6

may cause si. visible swell/loss of prop,

23

8

little/no effect-severe cond, may cause change

8

3

crude

8

>121

€

Phenol 23 carbolic acid

minor to moder. effect recommended for use

8

little/no effect-severe cond. may cause change

(FKM)

exc. mi$l> JiUIe or no effect

3M Fluorel (FKM)

3

9

70

28

7

7

85

100

A-11

10

89

140

A-14

0

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

28

5

100

28

8

10

exc. resist* little or no effect

149

28

6

24

good-exc, resist,, motfer, effect

150

28

2

24

70

8

with 15% H2O

85

8

technical

65

biphenyl/diphenyl

57

210

A-19

U

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A2

8

recommended for use

a

little/no effect-sevgre cond may cause change

(FKM)

dissolved

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8 O 131

Phenylethyl Ether

unsatisfactory for use 2 1

phenetole

3M Fluorel (FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use 2

7

as

PDA

3M Fluorel (FKM)

8

with 30% H2O

Phenyl Benzene

recommended tor use

a$

66

(FKM)

exc. resist.t little or no effect

8 <121

3M Fluorel FLS 2330 (FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

23 7

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

below 250 deg

25

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-10

6

25

Petroleum Oil

Phenylenediamine

recommended for use tittle/no effect-severe cond. may cause change

above 250 deg

Petroleum Ether

Phenolsulfonic Acid

8

8

23

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8 7

Material Note

recommended lor use

Pentoxol

Pentane (N-)

Resistance Note

not suitable for service

(FKM)

23

(Cont'd.)

Table 7.1 (Cont'd.) % Retained

% Change Reagent

Reagent Note

Cone. Temp. Time PDL ( 0 C) Ways) Rating (%)

Phenylhydrazine 23 Phorone diisopropylidene acetone Phosphoric Acid

23

3 molar

Volume

Tensile Modulus Elongation Hardness Strength Change

8

recommended for use

8

little/no effect-severe cond. may cause change

2

unsatisfactory for use

1

not suitable for service

8

recommended for use

20

8

33

45 45

23

60

100

28

60

100

28

little/no effect-severe eond. may cause change

8

recommended for use

a

Kttte/no effect-^vere cpnd> may cause change

7 8

4

89

110

A-8

4.2

23 205

little/no effect-severe cond. may cause change

8 1

A

98

85

87

A19

1

5

42

75

113

A9

Pickling Solutions 23

(FKM) (FKM)

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

recommended for use (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

205 6

minor to moder. effect

6

may cause si. visible swell/loss of prop,

8

recommended for use

(FKM)

8

molten 23 Pine Oil

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc, resist,, little or no effect

8

Phosphorous Trichloride

H2O solution

(FKM)

8

20

Picric Acid

Material Note

8

concentrated

Phthalic Anhydride

Resistance Note

white

8

little/no effect-severe cond. may cause change

8

recommended for use

(FKM)

8 white

23

8

23

8 8

Pinene 70

7

Piperidine 23 Hercoflex 600, Hercules Plasticizers

(FKM)

recommended for use

8

23 Pinene flJ-)

Plating Solutions

little/no effect-severe cond. may cause change

tittle/no effectsevere cond. may cause change

8

A6

2

unsatisfactory for use

1

not suitable For service

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

150

14

6

17

76

100

A-14

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

14

4

13

66

133

A-11

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

chrome

8

others

8

chrome

23

8

others

23

8

recommended for use little/no effect-severe cond, may cause change

Pneumatic Service

8

recommended for use

Potassium Acetate

2

unsatisfactory for use

23 Potassium Chloride 23 Potassium Cuprocyanide 23 Potassium Cyanide 23

1

not suitable for service

8

recommended for use

8

tittle/no effecf-severe cond. may cause change

8

recommended for use

8

tittle/no effect-severe cond. may cause change

8

recommended for use

8

little/no effect-severe cond. may cause change

(FKM)

(FKM) (FKM) (FKM) (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

% Change Reagent

Reagent Note

Cone. Temp. Time PDl Ways) Rating {%)

Potassium Dichromate 23 Potassium Hydroxide 23 Potassium Nitrate 70

% Retained Tensile Modulus Elongation Hardness Strength Change

5

Resistance Note

8

recommended tor use

8

little/no effect-SBvere cond. may causa change

6

minor to rooder. effect

1

not suitable for service

8

recommended fof use

a

23 30

Potassium Permanganate

Volume

6

Potassium Salts

8

Potassium Sulfate

$

fitt1$/no eftect^evere cond. may cause change 28

A-11

littte/no effect-severe cond. may cause change

8

recommended lor use

Producer Gas

8

(FKM)

(FKM)

8

Propane 125 psi

3

160 psi

3 23

Propane Propionitrile

6

2

exc, resist., little or no effect

11

good-exc. resist, moder. effect

8

little/no effect-severe cond. may cause change

8

recommended for use

2

Propyl Acetate n-propyl acetate

20

8

methyl butyl ketone

1

23

not suitable for service

2

unsatisfactory for use

1

not suitable For service recommended fof use

20

8

9

0.6

20

21

8

2

23

n-propyl alcohol

25

21

8

2

70

4

8

6

20

7

2 1

140

n-propyl Nitrate

25

Propylene 23 Propylene Oxide 23 Pydraul 1OE 23 Pydraul 115E hydraulic fluid; Monsanto

23

A10

1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent Kftla/no attect-severa cond, may cause change

(FKM)

good-exc. resist., moder. affect

3M Fluorel (FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

140

A-38

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorei (FKM)

8

recommended iat use

8

tittte/no effect-severe cond. may cause change

2

unsatisfactoryioruse

1

not suitable for service

8

recommended lor use

8

littte/no effect-severe cond. may causa change

8

recommended for use

8

little/no effect-severe cond. may causa change

8

recommended tor use

23

8

litUa/no a*fect-$evera cond may causa change

23

8

little/no effect-severe cond. may causa change

8

recommended for use

Pydraul 230E U

7

(FKM)

unsatisfactory for use

1

23

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

1-propanol

Propyl Nitrate

(FKM)

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

Propyl Alcohol

3M Fluorel (FKM)

unsatisfactory for use 200

1

23 Propyl Acetate (N-)

Pydraul 29 ELT

(FKM)

recommended for use

8

Propyl Acetone

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Potassium Sulfite

23

Material Note

(FKM) (FKM) (FKM) (FKM) (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Pydraul 3OE

Reagent Note

Cone. Temp. Time PDl Ways) Rating ( 0 C) (%)

hydraulic fluid; Monsanto

23 70

Pydraul312

U

7

Pydraul 65E

118

A5

72

120

A-10

4

110

130

AO

3

104

110

AO

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

121

14

recommended for use Kttte/no effect-severe cond. may cause change

14.6

9

5

95

105

AO

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

14.6

8

6

85

103

A3

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

121 121

83

6

78

103

A-2

83

a 7

6

90

121

A-2

1

8 8 8 8 8 8 3

23 66

14 7 7

8 8 8 a 8 8 9

fittle/no effect-severe cond. may cause change fcWe/no effect-severe cond. may cause change

recommended lor use little/no effect-severe cond. may cause change

2.7

RJ 1

little/no effect-severe cond. may cause change

(FKM)

exc, resist, r little or no effect

3M Fluorel (FKM)

3 DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-1

2

recommended for use

149

7

8

5

little/no effect-severe cond. may cause change

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist., little or no effect

3M Fluorel (FKM)

unsatisfactory (or use

2

20

3

3

120

20 23 25

7

1

119

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-15 21

67

A-25

1

Pyrrole

(FKM)

recommended for use

4

23

(FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

60

8

Pyroligneous Acid

(FKM)

recommended for use

9

1

(FKM)

recommended 1or use

4

3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent little/no effect-severe cond, may cause change

23 100

oil

RJ1;MIL-F-25558B

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

121

a

RJ-1, petroleum base

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A6

121

23 82 100 70

GE hydraulic fluid

Ramjet Fuel

89

7 9

Pyranol

Pyridine

5 10

14

Pydraul 9OE

Transformer Oil, GE

Material Note

7 6

121

23

Pydraul F9

Resistance Note

118

7

hydraulic fluid; Monsanto

Pydraul A200

Hardness Change

91

28

23

Monsanto, industrial hydraulic fluid

Tensile Modulus Elongation Strength

2

1QO

Pydraul 540C Pydraul 60

% Retained

Volume

8 8 8

100

23

Pydraul 312C Pydraul 312E Pydraul 5OE

% Change

120

not suitable for service

(FKM)

not recommended, substantial effect

3M Fluorel (FKM)

2

unsatisfactory for use

1

not suitable for service

2

unsatisfactory for use

23 20

28

9

1

23 24

28

6 9

1

not suitable for service

1 A-2

little/no effect-severe cond. may cause change exc. resist., littfe or no effect

(FKM) (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM) 3M Fluorel (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time PDl Ways) Rating (%)

Rapeseed Oil 23 RD 6195

Red Oil

Monsanto, hydraulic fluid

Tensile Modulus Elongation Strength |

recommended tor use (FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

2.7

150

40

5

3

199

40

6

20

200

40

4

20

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent good-exc, resist., mader. effect

39

36

A-6

8

recommended for use

9

1

7

9

0

MIL-L-23699

205

3

a

12

6 8

A-4

130

A-6

66

96

A-14

19

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist., little or no effect 78

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use

28

MIL-H-25576 C

A-5

little/no effect-severe cond. may cause change

20

3

132

8

200

205

57

8

Shell

MIL-R-25576

Material Note

little/no effect-severe pond, may cause change

RP-1, petroleum base

RP 1

Resistance Note

8 8

MIL-F-25558

Hardness Change

8 40

MIL-H-5606

Rotella Oil Royco 899

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use

23

8

KttleAio effect-severe cond- may cause change

(FKM)

24

9

exc, resist, little or no effect

3M Fluorel (FKM)

28

Sal Ammoniac 23

Salicylic Acid 23

Salt Brine Santosafe 300

% Retained

Volume

149

23

RJ 1 Rocket Fuel

% Change

chlorinated

8

0.9

recommended for use

8

fit tie/no effect-severe cond. may cause change

8

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use

(FKM) (FKM)

8 70

7

8

1

91

118

A3

100

7

7

3

83

110

A5

8

23

Sea Water

little/no effect-severe cond. may cause change

25

30

9

1.5

100

30

8

4.5

200

3

5

24

59

100

A-14

200

3

6

16

75

90

A-11

20

6.9

7

106

120

exc, resist, little or no effect

Shinol TWS-R

Silicone Greases

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

rBcommendBd for use

23

8

tittle/no effect-severe cond, may cause change

23

a

Silicate Esters

(FKM) 3M Fluorel (FKM) 3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

recommended for use

8

Sewage Shell Turbine No. 307

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(FKM)

recommended for use

8

a

Silicone Oils

littie/no effect-severe cond, may cause change

8

23 F 60, low viscosity

1$O

28

9

0.1

A-5

F 61, high viscosity

150

28

9

0.7

A-1

DC 200, Dow Corning

175

28

9

-2

A2

Silver Nitrate 23

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

recommended for use

8

little/no effect-severe cond, may cause cfiange

(FKM)

{Cont'd.)

Table 7.1 (Cont'd.)

Reagent Skelly Solvent

Reagent Note

Cone. Temp. Time P D l (days) Rating ( 0 C) (%)

Skydrol 500B

fire resist, hydraulic fluid

aircraft hydraulic fluid

Monsanto; hydraulic fluid

Soap

7

1

174

12

45

A-54

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

7

1

171

27

61

A-22

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

121

7

2

151

23

90

A-44

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

121

7

3

45

50

81

A-20

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

121 121

14

4 1

31

62

90

A-22

92

35

60

A-27

150 150

7

139

16

61

A-56

236

13

35

A-54

14

(FKM)

good-exc. resist., moder. effect

3M Fluorel FLS 2330 (FKM)

266

11.4

22

A-52

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2OQ

3

15

36

33

A-4

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

200

3

4

12

34

61

A-5

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

200

14

17

13

30

A-1

200

14

4 4

24

14

19

A-4

1

8 8 8 8 8

88

93

AO

8 7

78

112

A-4

102

97

A-1

23

121 121

1

175

.1.

175

7

177

1

177

7

23

Sodium Bicarbonate 23 baking soda 23

Sodium Borate 23

soda ash

45

6 6 4

Sodium Acetate

Sodium Carbonate

unsatisfactory for use not suitable for service

1 1

23

Sodium Bisulfite

recommended for use

7

23

vapor, N2 atmosphere liquid vapor, nitrogen atmosphere

Material Note

150

solutions

liquid

Resistance Note

7

Soda Ash Sodium

Hardness Change

7

Skydrol 7000 Skylube 450

Tensile Modulus Elongation Strength

23 149 150

solvent E

Skydrol 500 Skydrol 500A

% Retained

Volume

8 a 8 2 1. 5 1

solvent B solvent C

Monsanto; hydraulic fluid

% Change

9 8 8

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent minor to moder. effect may cause si. visible swell/loss of prop.

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended lor use little/no effect-severe cond. may cause change

(FKM)

recommended tor use little/no effect-severe cond. may cause change

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist., little or no effect

3M Fluorel (FKM) DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist., little or no effect

2 1 8 8

little/no effect-severe cond. may cause change

a

recommended for use

8 8 8 8

littte/no effect-severe cond. may cause change

3M Fluorel (FKM)

unsatisfactory for use not suitable for service

(FKM)

recommended for use (FKM) (FKM)

recommended for use littfe/no effect-severe cond, may cause change

(FKM)

recommended for use

(Cont'd.)

Table 7.1 (Cont'd.)

% Retained

% Change Reagent

Reagent Note

Cone. Temp. Time tfays) ( 0 C) (%)

Sodium Chloride 23 Sodium Cyanide 23 Sodium Hydroxide

Volume

Tensile Modulus Elongation Hardness Strength Change

Resistance Note

8

recommended tor use

8

little/no effect-severe cpnd. may cause change

8

recommended for use

8

little/no effect-severe cond. may cause change

6

mfrtor to moder. effect may cause si. visible swell/loss of prop.

6

23

Material Note

(FKM) (FKM) (FKM)

30

70

14

5

34

53

114

46.5

20 38

7

8

2

75

100

A1

46.5

180

6

73

86

A-5

46.5

38

365

5

54

81

A-6

46.5

38

730

3

32

67

A-9

46.5

38

1095

2

17

62

A-17

50

24

7

9

2.1

exc. resist., little or no effect

50

38

180

7

-9.5

good+exc. resist., mqder. effect

50

70

7

8

0.5

50

70

14

6

-7

69

115

A3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

50

70

14

6

-8

47

120

A-2

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Sodium Hypochlorite 23

recommended for use

9

0.8

5

24

28

9

0.8

5

70

28

7

24

20

70

28

7

24

23 Sodium Peroxide 23 dibasic

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

{fttJa/no effect-severe cond. may cause change

28

23

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

20

Sodium Perborate

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-10

8 5

Sodium Metaphosphate

Sodium Phosphate

PDt Rating

exc. resist, little or no effect 89

110

exc. resist,, little or no effect

8

little/no effect-severe cond, may cause change

8

recommended: for use

8

littte/no effect-severe cond, may cause change

8

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use

8 8

a

{(ttte/no effect-sevBre cond. may cause change

Sodium Salts

8

recommended 1of use

Sodium Silicate

8

23

Sodium Sulfate 23 Sodium Sulfide Sodium Sulfite

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-6

recommendedforuse

mono

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

tribasic

3M Fluorel (FKM)

8

recommended fof use

8

[fttfe/no effect-severacond. may cause change

8

recommended lor use

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended (FKM) (FKM) (FKM)

(FKM)

(FKM)

8

Sodium Thiosulfate

8 23

Irttte/no effect-severe cond, may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time PDl {days) Rating ( 0 C) (*)

9

0.5

8 4 a 8 9

9

exe. resist., little or no effect

24

not recommended, substantial effect

Sour Gas

3

Soybean Oil 23 121

7

24

7

fuel fuel 7

and water

recommended for use 0.8

exc. resist., little or no effect

3M Fluorel (FKM)

recommended for use exc. resist., little or no effect

2.3

1

8 7

1

100 100 100 121 121

3M Fluorel (FKM) (FKM)

recommended for use

little/no effect-severe cond. may cause change

(FKM)

109

120

2

89

176

A2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

4

3

42

230

A-7

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3

9

1.3

14

1.4

7

9 9 6 9

125

50

5

14£

21

8

21

1 1 5

70

81

A-7

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

162

7

7

6

73

95

AO

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

162

7

9

1

94

105

A4

45

91

A-13

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

4

34

140

A-11

-2

82

106

A7

13

49

70

A-5

2

87

105

A2

<*49 >149 150

Steam

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

6.9

1.4MPa, 200 psig

and water

0.4

little/no effect-severe cond. may cause change

23 20

3M Fluorel (FKM)

recommended for use ItKIeA)O effect-severe cond, may cause change

8 8 8 8 7

23

Stannous Chloride

Stauffer 7700 Steam

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use

50 aqueous

8 9 a &

Material Note DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

a

Stannic Chloride

Stannous Fluoroborate

Resistance Note

7

50 24 70

aqueous

Hardness Change

7

7

24

Tensile Modulus Elongation Strength

1

50

SR 6

% Retained

Volume

9

Sodium Thiosulfate

SR 10

% Change

42 7

162

9

4

162 162

14.6

4 8

162 162

14.6 21 21

5 9

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use

exc. resist., little or no effect

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

1.8 10.8

good-exc, resist,, moder, effect

3M Fluorel (FKM)

1.5

exc. resist., Iittte or no effect

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

64

75

A-9

6

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

not suitable for service

(FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Steam

Steam

and water

Cone. Temp* Time PDl Ways) Rating ( 0 C) (%)

Styrene

styrene monomer

Sucrose

SBR polymerization modifier, Phillips

Sulfur

liquors

9

A-3

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

46

87

A-3

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

175 <177 >177 197

50

15

49

A-13

7

2 2 2 2

200 204 204

0.3 3 3

9 8 7

204

7

8

204

14

20

7

7 8 8 $ 6 8

20

28

4

7 7

6 6 5

23

23 25 50

ZZ 23 20

7

23 Sulfur Chloride

Sulfur Dioxide

23 20

wet liquid moist

2

8 8 8 8 9 8 8 8 8 8 8 9 8 2

dry liquidified; under pressure dry

Material Note

5

molten

Sulfur Oichloride

Resistance Note

4

Sulfite Liquors Sulfole

Hardness Change

6

solutions solution

Tensile Modulus Elongation Strength

170

monomer styrene monomer

% Retained

Volume

175

Stoddard Solvents white spirits

% Change

23 23 23

Sulfur Hexafluoride 23 Sulfur Trioxide 23

8 8 8 8 4 6 8 8

0.7

unsatisfactory tor use 29

49

1 O 3 1 2

A16

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-1 good-exc. resist, moder. effect

3M Fluorel (FKM) 3M Fluorel FLS 2330 (FKM); compounds w/ lead based metal oxides recommended

82

110

A-1

68

114

A-5

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended for use ffttfe/no effect-severe cond. may causa change

(FKM)

minor to modsr effect

6 11

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent -16

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent may cause si. visible swell/loss c-J prop,

11 31

good-exc, resist., moder, effect

(FKM) 3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use littte/no effect-severe cond. may cause change

(FKM)

recommended for use little/no effect-severe cond. may cause change

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

-0.1 recommended for use

(ittle/no effect-severe cond. may cause change

(FKM)

recommended for use little/no effect-severe cond. may cause change

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3 recommended for use unsatisfactory lor use recommended for use littte/no effect-severe send, may cause change

(FKM)

moder. to severe effect may cause si. visible swell/loss sf prop,

(FKM)

recommended (or use littte/no effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time CC)

Sulfuric Acid

Ways)

3 molar concentrated dilute fuming; 20/25% oleum fuming, 20% oleum

Rating

Hardness Change

recommended iat use

a

3

A-5

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

9

4

A-2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

36

6

28

A8

20

24

20

fuming, 20% oleum

8 8 8 7 7

28 12

littfe/no effect-severe cond. may cause change

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

a

92.5

102.5

123

A-1

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco 101XL: TAIC

7

6

82

123

66

AO

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak #1

24

7

7

95

127

90

A-1

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoylperox.

20

100

3

9

-2

106

A2

40

115

28

6

27

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

51

38

17

8

8

60

70

7

9

0.5

60

70

28

8

0.5

90

90

A-11

60 90

121 38

28 180

8 8

10

90 119

100 95

A-5

90 90 90 95 95

38 38 38 20 20

365 730

14 14

1 0.2 0.5

103 101 102 99 104

100 98 86 95 100

A2

1095

9 9 9 $ 9

95 98

70 20

28 7

8 9

5 7

88 101

90 108

102

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent 6KC, resist. t little or no effect

Sulfuric Acid

Material Note

7

20

dilute 25% Oleum

Resistance Note

7

36 7 7

concentrated

with 28% nitric, 4% HNOSO4,17% water

Tensile Modulus Elongation Strength

20

23 23 23 24 25 24

20% oleum

Sulfuric Acid

% Retained

Volume

8 8 8. 8 8

20% oleum

fuming

% Change

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A2

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A3 A3 AO A6

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A1 A-2

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

98

20

30

8

10

A6

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

98

20

30

8

7

A-5

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

98

100

14

6

21 good-exc. resist., moder. effect

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

(Cont'd.)

Table 7.1 (Cont'd.) % Change Reagent

Reagent Note

Cone. Temp. Time PDl tfays) Rating (0C) (%)

Sulfurous Acid 20

5% sulfur dioxide

7

23 SX 90

Mobil Oil

90

tannin

23

21

Tannic Acid 10 Tar Tartaric Acid

Tellus 33

Resistance Note

severely cracked and swelled

8

little/no effect-severe cond. may cause change

(FKM)

exc. resist., iittle or no effect

3M Fluorel (FKM)

g

recommended lor use

0.7

8

recommended Io r use

8

little/no effect-severe cond. may cause change

8

recommended lor use

8

little/no effect-severe cond, may cause change

8

recommended for use

23

8

little/no effect-severe cond. may cause change

23

1

not suitable for service

Shell

70

Tetrabromoethane

28

9

0.6

exc. resist., little or no effect

8

recommended for use little/no effeci-sevefe cond. may cause change

23

8

23

8 8

recommended for use

23

8

little/no effect-severe cond. may cause change

8

recommended lor use

Tetrabromomethane Tetrabutyl Titanate

8

23 Tetrachloroethane

Material Note

8 1

toluene diisocyanate

Terpineol

little/no effect-severe cond, may cause change

20

21

7

3

25

21

8

3

8

Tetrachloroethylene 20

14

23 Tetraethyllead

% Retained Tensile Modulus Elongation Hardness Strength Change

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(FKM)

8

bituminous 23

TDI

Volume

blend

9

A10

(FKM) (FKM) 3M Fluorel (FKM) (FKM)

(FKM) (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist., little or no effect

3M Fluorel (FKM)

recommended for use 2

8

little/no effect-severe cond. may cause change

8

recommended for use

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

8 23 Tetrahydrofuran 20

6

7

Tetralin tetrahydronaphthalene, Dupont

23

unsatisfactory lor use

1

281

1

not suitable for service recommended for use

8

little/no effect-severe cond, may cause change

7

177

7

9

177

7

9

8

recommended for use 3.1

exc, resist, little or no effect

1.4

exc. resist., little or no effect

1.9

exc. resist,, little or no effect

recommended for use

8

Texamatic Fluid 3401

recommended for use

8

Texamatic Fluid 3525

recommended io r use

8

Texamatic Fluid 3528 Kearsley thinners

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

177

(FKM)

200

8

Texamatic Fluid 1581

Thinners

little/no effect-severe cond. may cause change

1

23 23

8 2

177

7

9

2.1

24

40

8

3.5

(FKM)

(FKM)

3M Fluorel (FKM) 3M Fluorel (FKM) 3M Fluorel (FKM)

exc. resist,, little or no effect 3M Fluorel (FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time PDt CC) {days) Rating (%)

Thionyl Chloride 20

28

23

with 20% toluene -2,6 diisocyanate

Chlorextol, AINsChalmers

3 4 3 4

52

75

22

67

70

7

5

13

70

7

8

95

93 70

4 14

6 6

95

70

80

20

7

7 7

8 8 8 8 8 8 8 7

automatic type A type A; Esso Texamatic «A» type A Esso,type A

23 100 100

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent (FKM)

recommended for use

7.8 7.5 20 29

(FKM)

exc, resist.> little or no effect

3M Fluore! (FKM)

good-exc. resist, mader. effect

may cause si. visible sweff/loss of prop,

(FKM)

recommended for use

8 4.8 17

little/no effect-severe cond, may cause change

(FKM)

exc, resist., little or no effect

3M Fluorel FLS 2330 (FKM)

good-exc, resistM moder. effect

3M Fluorel (FKM)

54

72

A-12

54

72

64

86 83

A-14 A-23 A-19 A-17

59

80

A-10

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

4

73

100

A-3

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

15 17

73

100

A-14

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

61

100

A-18

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

good-exc. resist., moder. effect

not suitable for service

3M Fluorel FLS 2330 (FKM)

(FKM)

unsatisfactory for use DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent

1 8 8 6 8

Material Note

may cause si. visible swetl/ioss of prop,

26

8

23 100

A-20

1 2 9

23

Resistance Note

may cause si. visible swell/loss of prop,

5

Mobilgas WA200; Type A

Transmission Fluids

83

365 730 1095 2

Pyranol

Transformer Oils

46

38 38 38 50

TDI

Hardness Change

recommended lor use

22

7 7 14 180

trinitrotoluene

1095 7 28 20

14 Toluene Diisocyanate Toluene Diisocyanide Toluene-2,4-diisocyanate

Tensile Modulus Elongation Strength

23 23 25 25 38

23 38 177 204 250 23

TJ 15

with 5% pyridine

% Retained

Volume

6 8 6 8 7 6 6 6 S 8 8 S 6 4

Titanium Tetrachloride

TJ 35 TNT Toluene

8 4

% Change

recommended for use tittle/no effect-severe cond. may cause change

6

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended tor use a recommended lor use

3 2

77

79

A-1

little/no effect-severe cond. may cause change

(FKM)

exc, resist,, little or no effect

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'cn

Reagent Transmission Fluids

Reagent Note super 284 OS19381 Satfa EC-3686 Esso,type A

Transmission Fluids

% Change

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Chance

135

3

7

3

85

73

A3

135 149 149 150

3 3 40 40

8 9 8

4

89

80

A1

petroleum base, Ford

175

3

Texamatic Fluid 1581, Texaco

175

7

Texamatic Fluid 3401, Texaco

175

7

Texamatic Fluid 3525, Texaco

175

7

Texamatic Fluid 3528, Texaco

175

7

Sunoco Sunomatic 136 ATF

121

14

Texaco TL-8262B ATF

121 121

14.6

Sunoco Sunomatic 136 ATF

14

7

1 4

74

105

A-11

1

80

100

AO

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

90

95

A2

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

1

80

88

A-2

2

95

95

AO

2

80

82

A2

0.6

96

104

A2

9 9

1

88 95

100

A-1

100

A-4

1

100

A-4

2

92

A3

2

95 73 100

100

AO

9 8 9 8 9

1

3 3

150

3

6

2

72

65

A3

150

3

7

2

82

73

AO

Sunoco Sunomatic 136 ATF

150

14

9

1

94

109

AO

Texaco TL-8262B ATF

150 150 150

14

9 6 8

2

90 67 94

96

A-2

69

A4

3

Dexron ATF

Chevron PD-4645 ATF Sunoco Sunamatic 141 ATF WSX-8762B, Exxon factory fill type

Sunoco Sunamatic 141 ATF WSX-8762B, Exxon Chevron PD-4645 ATF ATF 1, viscosity index 134, sap. no.53

14.6 14.6

3M Fluorel FLS 2330 (FKM) 3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

3

9

9 7 9

Sunoco Sunamatic 141 ATF

Material Note DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

exc. resist, little or no effect

14.6

Dexron ATF

Resistance Note

4.2

121 150 150

Texaco TL-8262B ATF

Transmission Fluids

Cone. Temp, Time PDl ( 0 C) {days) Ratincf (%)

2 2

76

A1

98 63

86

A-1

43

A8

71

A1

68

A1

150 150

41.7 41.7

9 5

163 163

3 3

7 7

2 1

74 79

103 163

3 7

7 3

1

80

71

A2

2.8

57.9

47

A-1

163 163 163

7 7 7

4 4 3

2.5

137.9

53

AO

2.9

64.4

53

A-1

2.6

34.2

25

A4

163 163 163

7 7 7

3 3 6

1.9

35.6

38

A3.5

2.1

45.9

48

A4

2

69

59

AO

163 163 175

7 14 3

6 6 7

2

74 62 76

64

A1

3

2 3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

showed cracking/crazing

3M Fluorel (FKM); 66 wgt.% fluorine; Shore

W

61

A2

84

A-1

3M (FKM/TFE); high fluoride (70 wgt.%) peroxide cured; Shore A76

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

M

DuPont Viton A (FKM); 20 phr MT black,. 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Transmission Fluids

Reagent Note

Cone. Temp. Time PDt (%) CC) {days) Rating

% Retained

Volume

Tensile Modulus Elongation Strength

175

3

7

2

77

82

A-1

ATF 3, viscosity index 136, sap. no. 2.0

175

3

7

2

75

78

A-1

ATF 4, viscosity index 140, sap. no. 6.0

175

3

7

2

76

80

AO

ATF 5, viscosity index 147, sap. no. 3.3

175

3

6

2

53

61

A-1

Chevron PD-4645 ATF

175

3

7

2

84

73

AO

Sunoco Sunamatic 141 ATF

175

3

7

2

76

64

AO

WSX-8762B, Exxon

175 177 177 177 177 177 20

3 3 3 3 3 3 30

6 S 9 9 9

2

67

62

A2

2.1

a

1.5

20

30

25

7

8

100

7 7

2 1 8 8 8 8 8 8 2 1 1 1

150

7

AFT 2 AFT 3 AFT 4 AFT 5 trifluralin-preemergent herbicide-Elanco

with water + 5% surfactant

50

Triacetin 23

Triaryl Phosphate 23

Tributoxyethyl Phosphate 23

Tributyl Mercaptan 23

Tributyl Phosphate 23 1OO

7 7

20

7

1 4 4 8 7

20

21

7

21 28 28

8 7 5 2

7

8 8

Trichloroacetic Acid 23

Trichloroethane

23 25 1OO 100

Trichloroethylene 20

Resistance Note

Hardness Change

ATF 2, viscosity index 140, sap. no. 2.0

AFT1

Treflan

% Change

Material Note DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2.6

exc, resist* little or no effect

3M Fluorel (FKM)

2.3 2.5 3 2

83

118

AO

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

91

144

AO

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent exc. resist., little or no effect

3.5

3M Fluorel (FKM)

unsatisfactory for use not suitable for service ;

(FKM)

recommended for use

little/no effect-severe cond. may cause change

(FKM)

recommended for use tittle/no effect-severe cond. may cause change

(FKM)

recommended for use little/no effect-severe cond. may cause change

(FKM)

unsatisfactory for use not suitable for service 380

not recommended, substantial effect

380 400

3

(FKM) 3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

moder. to severe effect moder./severe swell and/or loss of prop,

(FKM)

recommended for use 11

DuPont Viton; 20 phr MT black, 15 phr magnesia or litharge, curing agent A10

3

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent little/no effect-severe cond, may cause change

(FKM)

good-exc. resist., moder. effect

3M Fluorel (FKM)

46 46

31

60

A28

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent recommended f or use

10

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent

Reagent Note

Trichloroethylene

tetrachloroethylene

Cone. Temp. Time PDL CC) tfays) Rating (%)

175

A-18

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

7

€

7

65

86

A-5

20

14

9

4

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20 23 25 25 70 70

14

8 8 8 8 6 6

6

7 7 28 28

3 180 365 730 1095 14 14

6 8 7 9 8 8 6 6 7

6

little/no effect-severe cand. may cause change

(FKM)

exc, resist,, little or no effect

3M Fluorel (FKM)

7

3M Fluorel FLS 2330 (FKM)

15 15

good-exc, resist,, moder. effect 61

95

A-12

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

minor to moder. effect 13 98

100

AO

90

90

A-3 A-12

92

98

13

72

85

A-9

21

76

106

A-13

5

83

118

A-4

tittle/no eflecf-severe cond, may cause change

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

7

7 7

21

84

104

A-7

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150

7

8

7

93

110

A-3

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

150 150

14

6 7

7

81

125

A-6

20

74

86

A-2

18

62

70

A-13

7

71

83

A-3

140 150

7

14 21 21

23 71

6

30

8 8 9

7

8 € € 6 6

7

8 8 8

Trifluoroethane Trinitrotoluene Trioctyi Phosphate 23 70 china wood oil

23 149

3M Fluorel (FKM)

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent unsatisfactory for use not suitable for service

(FKM)

minor to moder. effect may cause si, visible swell/loss of prop.

30

Triethylborane 23 71

4 6

exc. resist, little or no effect

17

2 1 6

23

Triethylaluminum

Sunamatic 137

Material Note

62

Triethanolamine

Turbine Engine Lubricant

Resistance Note

9

150 150

Tung Oil

Hardness Change

4

38 38 38 100 100

Trioxane

Tensile I Modulus Elongation Strength

7

23 38 38

TEA

% Retained

Volume

20

Tricresyl Phosphate

Tricresyl Phosphate

% Change

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

30 recommended for use little/no effect-severe cond. may cause change 5

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use minor to moder. effect may cause sJ. visible swell/loss of prop, 23

(FKM) DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use 3

little/no effect-sever* cond. may cause change

(FKM)

exc, resist., little or no effect

3M Fluorel (FKM)

(Cont'd.)

Table 7.1 (Cont'd.) % Change Cone. Temp. Time PDl ttays) Rating CC) (W

Reagent

Reagent Note

Turbine Oil

#15; MIL-L-7808A

8

#35

8

Volume

% Retained Tensile Modulus Elongation Hardness Strength Change

Resistance Note

Material Note

recommended tor use

8 8

Turpentine

8

23

Ucon50HB100

70

28

8

9

70

28

7

8.6

Ucon 50HB55

38

205

14

9

lubricant

8

8

Ucon LB300

8

recommended 1o r use 44

8

oil

8

Ucon LB400X

8

lubricant

8

Ucon LB65 unsymmetrical dimethyl hydrazine

1

23 70

Univis J43

135

28

9

1.8

7

8

2.6

2

unsymmetrical (UDMH) 24

4

8

10

24

7

8

2.6

Varnish

23 23

not suitable for service

(FKM)

exc. resist., little or no effect

3M Fluorel (FKM)

unsatisfactory lor use

Valclene

Vegetable Oils

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

Ucon LB285

Unsymmetrical Dimethylhydrazine

A2

3

8

lubricant

Ucon LB135

UDMH

recommended l o i use

8 8

Ucon LB625

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

Ucon Hydrolube J4

Ucon LB385

A-7

8

Ucon 50HB660 Ucon LB1145

3M Fluorel (FKM)

8 oil; polyacrylonitrile glycol derivative heat transfer lubricant

Ucon50HB5100

105

(FKM)

exc. resist > little or no effect

8

lubricant

Ucon 50HB260 Ucon 50HB280X

84

little/no effect-severe cond. may cause change

exc. resist., iittte or no effect

8

recommended for use

8

little/no effect-severe cond. may cause change

8

recommended for use little/no effect-severe cond. may cause change

8

(FKM) (FKM)

20

30

5

12

69

118

A-10

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

30

6

2

88

133

A-7

DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent

Vernam

Versilube Versilube F50

3M Fluorel (FKM)

23 177

28

260

3

Vinegar 23

8

recommended for use

8

little/no effect-severe cond. may cause change

(FKM)

good-exc. resist, moder. effect

3M Fluorel (FKM)

7

3

7

-3

8

recommended fo ruse

8

little/no effect-severe cond. may cause change

(FKM)

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Vinyl Acetylene

Reagent Note

Cone. Temp. Time PDl (0C) tfays) Rating (%)

% Retained

Volume

Tensile Modulus Elongation Strength

Hardness Change

-20

7

23 20

7

7

A-2 littJe/no effect-severe cond, may cause change

8

recommended for use

7

7

6

drinking

8

salt water

8

Material Note

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8 12

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

8

23 25

$

Resistance Note unsatisfactory lor use

2

monovinyl acetylene

Vinyl Chloride Vinyl Fluoride

% Change

12

tittle/no effect-severe cond. may cause change

(FKM)

good-exc. resist., moder. effect

3M Fluorel (FKM)

recommended for use

8 distilled

Water

Water

20

30

9

0.6

A5

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

20

30

9

0.8

A-5

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

180

8

3

cold

23

distilled

70

8

iittle/no effect-severe cond. may cause change 69

100

AO

80

130

A6

(FKM) DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

70

365

7

11

70

730

6

5

plus 1% soluble oil

90

4.2

9

5

and steam

100

3

9

1.3

100

7

6

59.5

90

86

A-2

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco 101XL: TAIC

100

7

8

80

105

90

A-4

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoyl perox.

100

7

3

33

140

43

A-7

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak #1

distilled

100

10

9

104

111

A-1

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

and steam

100

14

9

1.4

distilled

100

28

9

0.3

99

117

A2

100

28

6

0.7

83

125

A-18

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2

and steam

1

exc. resist., little or no effect

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended exc. resist., little or no effect

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

30

8

117

AO

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

100

30

6

50.5

68.75

95

A-2

3M KeI-F 3700 (VDF/CTFE); Shore A65; 100:10:10:1:6 - KeI-F: ZnO2: Dyphos: Luperco 101XL: TAIC

100

30

6

65

91

103

A-10

3M KeI-F 3700 (VDF/CTFE); Shore A55; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: benzoylperox.

100

30

5

31.25

97

63

A-6

3M KeI-F 3700 (VDF/CTFE); Shore A53; 100:10:10:3 phr - KeI-F: ZnO2: Dyphos: Diak #1

100

42

9

104

1.8

3M Fluorel (FKM); compounds w/ lead based metal oxides recommended exc. resist., little or no effect

(Cont'd.)

Table 7.1 (Cont'd.)

Reagent Water

Reagent Note

Cone. Temp. Time PDt (0C) ttays) Rating (%)

and steam

distilled

Water

and steam

with glysantin 1:1

Whiskey White Oil

50

Hardness Change

Resistance Note

Material Note 3M Fluorel (FKM) 3M Fluorel (FKM); compounds w/ lead based metal oxides recommended

6 9

10.8

good-exc. resist., moder. effect

1.5

8KC. resist., little or no effect

149 162

21 7

8 8

6 9

86

95

A6

162

7

8

5

86

105

A-7

162 162

21 21

S 7

5 11

94 84

121 110

A-3 A4

170 170 175 204 204

4 8 6 3 3

9 9 5 8 7

2

90

4.2

9

2

23 25 25 70 70

7 14 28 28

8 8 8 8 8 8 8 8 8 9 7 6 5

20

10

9

23

23 Xenon Xylene

mixed aromatic amines di-methyl aniline

Tensile Modulus Elongation Strength

7 7

Wolmar Salt Wood Oil

Xylidine

% Retained

Volume

121 121

& wines

Xylene (m-)

% Change

23

Zeolites 23

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton GF (Perox. Cur.); 20 phr MT black, 15 phr magnesia or litharge, curing agent DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

A-3 A4

4 O

good-exc. resist., moder. effect

3

3M Fluorel (FKM) 3M Fluorel FLS 2330 (FKM); compounds w/ lead based metal oxides recommended DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

recommended for use tittle/no effect-severe cond. may cause change

(FKM)

recommended tor use

50

tittle/no effect-severe cond. may cause change

126

(FKM)

recommended lor use

2

little/no effect-severe cond. may cause change

(FKM)

exc. resist., littte or no effect

3M Fluorel FLS 2330 (FKM)

12

3M Fluorel (FKM)

18

good-exc, resist., moder. effect

A-16

18

DuPont Viton A (FKM); 20 phr MT black, 15 phr magnesia or litharge, curing agent

5

DuPont Viton B (FKM/TFE); 20 phr MT black, 15 phr magnesia or litharge, curing agent

2 1 8 8

unsatisfactory for use not suitable For service

(FKM)

recommended for use little/no effect-severe cond. may cause change

(FKM)

unsatisfactory for use

Zinc Acetate 23 Zinc Chloride 23 Zinc Salts Zinc Sulfate 23

1 8 8 8 8 8

not suitable for service

(FKM)

recommended for use

66

85

little/no effect-severe cond. may cause change

(FKM)

recommended for use little/no effect-severe cond. may cause change

(FKM)

192

FLUOROELASTOMERS HANDBOOK

Table 7.2 Fluid Resistance of Fluoroelastomer Families[4]

Fluoroelastomer Type Composition % Fluorine

A

B

VDF/HFP 66

Cure System

F

GB

GF

VDF/HFP/TFE 68

70

67

GLT

GFLT

VDF/PMVE/TFE 70

Bisphenol

64

67

Peroxide

Typical % Volume Change, 75-durometer vulcanizate Fuel C, 7 days / 23ºC

4

3

2

5

2

Methanol, 7 days / 23ºC

90

40

5

90

5

>200

>200

>200

>200

>200

Methyl ethyl ketone, 7 days / 23ºC Potassium hydroxide, 7 days / 70ºC

Samples highly swollen and degraded

Service Rating Hydrocarbon Auto, Aviation Fuels Oxygenated Auto Fuels

E

E

E

E

E

E

E

NR

VG

E

VG

E

NR

E

Motor Oils SE-SF Grades

VG

E

E

E

E

E

E

SG-SH Grades

G

VG

VG

E

E

E

E

Aliphatic

E

E

E

E

E

E

E

Aromatic

VG

VG

E

E

E

VG

E

G

VG

VG

E

E

E

E

Amines; high pH aqueous base

NR

NR

NR

NR

NR

NR

NR

Low mol wt ketones and esters

NR

NR

NR

NR

NR

NR

NR

Hydrocarbon Process Fluids

Aqueous Fluids: Hot water, Steam, Mineral Acids

Service Ratings: E - Best choice for service; minimal volume increase or change in physical properties. VG - Good serviceability; small volume increase and/or changes in physical properties. G - Suitable for service; acceptable volume increase and/or changes in physical properties. NR - Not recommended; excessive volume increase or change in physical properties.

7 FLUID RESISTANCE OF VDF-CONTAINING FLUOROELASTOMERS

193

REFERENCES 1. Chemical Resistance Volume 2: Elastomers, Thermosets and Rubbers, PDL Handbook Series, Chemical Resistance - FKM, VDF/CTFE, FKM/TFE Fluoroelastomers, Second Edition, pp. 190–254, William Andrew Inc., Norwich, NY (1994) 2. Chemical Resistance Guide, DuPont Performance Elastomers, Viton ® Technical Information, www.dupontelastomers.com (2005) 3. Dyneon® Fluoroelastomer Chemical Resistance, Product Information Bulletin 98-0504-1316-4 www.Dyneon.com (2000) 4. Viton® Fluoroelastomer Selection Guide, Technical Information Bulletin 301794A (1998)

8 Fluid and Heat Resistance of Perfluoroelastomers 8.1

Introduction

Perfluoroelastomers are copolymers of TFE and PMVE or a perfluoro(alkoxyalkyl vinyl ether) with various cure sites incorporated, as described in Sec. 2.4. The chemical resistance of perfluoroelastomer vulcanizates approaches that of polytetrafluoroethylene (PTFE) thermoplastics. The heat resistance of perfluoroelastomer vulcanizates depends mainly on the cure system used, as discussed in Sec. 5.3. Peroxide-curable perfluoroelastomers are sold to selected fabricators by Daikin and Solvay Solexis. DuPont Performance Elastomers sells fabricated perfluoroelastomer parts, based on proprietary compounds of various polymers and cure systems. Information available from perfluoroelastomer parts suppliers does not always allow identification of the polymer composition, cure system, and compound ingredients for a given product. The original Kalrez ® perfluoroelastomer parts were based on a bisphenol cure system that gives excellent fluid and heat resistance. Later perfluoroelastomer products (e.g., Daikin Perfluor) based on peroxide cure systems have excellent fluid resistance, especially to hot aqueous media, but much lower heat resistance. Fabricated parts from Kalrez® 4079 make up a large fraction of DuPont perfluoroelastomer production. Curing is effected by catalyzed reaction of –RfCN groups to form highly stable triazine cross links. Solvay Solexis has recently developed peroxide-curable perfluoroelastomers with excellent heat resistance.

8.2

lar results. For long-term exposure to hot aqueous environments, perfluoroelastomers cured with peroxide or bisphenol are more stable than those with triazine cross links. More detailed fluid resistance information, including product recommendations for service at various temperatures, is available in the interactive Chemical Resistance Guide for Kalrez® on the DuPont Performance Elastomers website.[2] A summary of chemical resistance for perfluoroelastomers cured with various systems is shown in Table 8.2.[3] For the Kalrez compounds listed, 1050LF is cured with bisphenol, 2035 is cured with peroxide and radical trap using a bromine-containing cure site, 4079 has triazine cross links, and 6375 has a proprietary cure system probably based on –RfCN cure sites. Some differences in fluid resistance are noted in Table 8.2 that are not apparent in the Table 8.1 listing which does not contain information on compounds with different cure systems. Iodine-containing Daikin Perfluor and Solvay Solexis Tecnoflon PFR polymers cured with peroxide would have broad fluid resistance similar to that for the Kalrez 2035 compound. This includes the major fluid seal compound, Chemraz® 505, offered by Greene, Tweed & Co., apparently based on peroxide-cured Perfluor.[4] The information in these tables should be used only for initial guidance. When exposure conditions are known for a given application, suppliers of perfluoroelastomers or fabricated parts can give better recommendations for specific compounds that will give satisfactory service. In many cases, decisions should be based on performance requirements other than fluid resistance.

Fluid Resistance Data

Table 8.1 contains a tabulation of chemical resistance for perfluoroelastomer vulcanizates, taken from a previous volume in the PDL Handbook Series.[1] The standard ASTM designation FFKM for perfluoroelastomers is used in the table. All the data are for DuPont Kalrez® perfluoroelastomer vulcanizates exposed to fluids at temperatures up to 100°C. Under these conditions, the perfluoroelastomers are resistant to most of the test fluids, so PDL ratings are high (usually 8), indicating suitability for service. (See Appendix for a more complete description of the PDL Ratings.) Other perfluoroelastomers would give simi-

8.3

Heat Resistance Data

Some heat resistance data for perfluoroelastomers cured with various crosslinking systems were shown in Table 5.8, recording changes in tensile strength after ten days of exposure at several temperatures. Data such as these were used to recommend upper temperatures for continuous service of various Kalrez compounds, as listed in Table 8.3.[5] The heat resistance of TFE/PMVE perfluoroelastomers with –RfCN cure sites that form triazine cross links is outstanding, with long-term service over

196 300°C possible. Bisphenol-cured perfluoroelastomers also have excellent thermal stability. Such compounds require long press cures, followed by very long (40 hours or more) oven postcuring under nitrogen at high temperature. Most fabricators of fluoroelastomer parts do not have capability for such curing operations, so DuPont Performance Elastomers makes and sells perfluoroelastomer fabricated parts, largely through a distributor network. The upper service temperature limit for peroxide cures of perfluoroelastomers with iodine or bromine cure sites using triallylisocyanurate (TAIC) as radical trap (crosslinking agent) is the same as that for VDF-containing fluoroelastomers. Some improvement is obtained when perfluoroelastomers with –RfCN cure sites are cured with peroxide and TMAIC.[6] As noted in Sec. 5.3, Solvay Solexis has developed peroxide-curable perfluoroelastomers with enhanced heat resistance. [7] These polymers are made in a microemulsion “living radical” semibatch process, with I(CF2)6I transfer agent charged initially to get chains with iodine end groups and with CH2=CH–(CF2)6– CH=CH2 fed during the course of the polymerization to get significant branching and some pendant vinyl groups. The branched polymer chains contain more than two iodine groups per chain. Heat-aging data for two peroxide-cured Tecnoflon PFR perfluoroelastomer compounds are shown in Table 8.4. PFR 94 is cured with peroxide and TAIC trap to give vulcanizates with stability similar to that usually obtained with other fluoroelastomers containing iodine end groups.[8] PFR 95, a similar branched polymer which may contain considerable pendant vinyl groups and probably additional CH2=CH–(CF2)6–CH=CH2, is cured with peroxide only (no TAIC) to give a vulcanizate stable up to 290°C.[9] Evidently, cross links based on divinylperfluoroalkane are more stable than those from triallylisocyanurate. Recently, Greene, Tweed & Co. developed Chemraz 615 seals for high-temperature service[10] up to 324°C. O-ring compression set resistance is claimed to be better than that of compounds like Kalrez 4079. The polymer and cure systems were not disclosed. The heat resistance information in this section is for exposure to hot air and should be used for general guidance only. For exposure to other environments at high temperature, recommendations should be obtained from perfluoroelastomer parts’ suppliers.

FLUOROELASTOMERS HANDBOOK

8.4

Resistance to Special Environments

High-cost perfluoroelastomers are mainly used for seals in environments to which hydrofluorocarbon elastomers are not sufficiently resistant to give adequate service life. Perfluoroelastomers have low swell in polar fluids that excessively swell VDF-containing fluoroelastomers, and are resistant to strong organic and inorganic bases and acids that may degrade VDFcontaining fluoroelastomers. Perfluoroelastomers are also resistant to strong oxidizing agents which attack fluoroelastomers containing either VDF or olefin monomer units. Several perfluoroelastomer compounds have excellent heat stability, allowing longterm service at 275°C–320°C, well above service limits for hydrofluorocarbon elastomers. Perfluoroelastomers have mediocre low-temperature flexibility. TFE/PMVE copolymers have glass temperatures of about -5°C, while Daikin copolymers of TFE with a perfluoro(alkoxyalkyl vinyl ether) have somewhat lower Tg, about -15°C. In common with other fluoroelastomers with high TFE content, perfluoroelastomers have low brittle points, near -40°C, so static seals may function at temperatures down to about -20°C, considerably below their Tg. Thermal expansion of perfluoroelastomer compounds must be taken into account, especially for seals for high-temperature service. For compounds with medium hardness, the coefficient of linear expansion is about 3.2 × 10-4/°C.[11] For a temperature rise of 200°C above ambient, linear dimensions of a perfluoroelastomer seal would increase by 64%. Thus, an o-ring groove must be sized to allow for such a large dimensional increase so that the seal does not overfill the groove and extrude at high temperatures. Part of the reason for such high thermal expansion is that perfluoroelastomer compounds generally contain low filler levels, typically 10–15 phr of black. Hardness increases greatly at higher black levels.

8.5

Major Applications

Most perfluoroelastomers are used in high-performance seals in several application areas: chemical processing industry, oil fields, aeronautical, pharmaceutical, and semiconductor fabrication. Lower-cost fluoroelastomers are also used in many of these areas, but perfluoroelastomers have greater

8 FLUID AND HEAT RESISTANCE OF PERFLUOROELASTOMERS resistance to the more severe environments often encountered, and provide assurance of long-term performance. Perfluoroelastomers are often economical when the costs of seal failure are high, involving high downtime and replacement costs, environmental emissions or spills, safety of people, or contamination of products. In the chemical processing industry, perfluoroelastomer seals provide long-term service in most fluids and mixtures. Typical parts include o-rings, valve stem packing, gaskets, and diaphragms. With more stringent requirements for avoiding emissions and chemical spills, perfluoroelastomer use has been increasing. Service temperatures are usually below 200°C in most chemical processes, so peroxide-cured fluoroelastomer compounds, such as Greene, Tweed Chemraz® 505, are generally satisfactory. DuPont has offered several compounds with different cure systems to meet chemical processing industry requirements over a wider range of temperatures (e.g., Kalrez® 4079, 1050LF, and 2035). Recently, compounds with a wide range of fluid resistance and with very high temperature resistance have been developed, including Kalrez® SpectrumTM 6375[3] and 7075 and Chemraz® 615.[10] Characteristics of these compounds are listed in Table 8.5. Of these compounds, Kalrez® 4079 is not recommended for service in hot water, steam, or amines. Oil field applications require seals with good resistance to base-containing organic and aqueous mixtures. At depths below about 18,000 feet (5500 m), high temperatures result in significant concentrations of hydrogen sulfide and carbon dioxide. Perfluoroelastomer compounds have been developed that are resistant to the environments encountered in deep wells. Special compounds with high black loading are designed to minimize damage from explosive decompression. This phenomenon occurs when pressure is reduced on a compound which contains a high concentration of carbon dioxide (CO2 is quite soluble in perfluoroelastomers). In aeronautical applications, perfluoroelastomers may be necessary for seals against jet aircraft engine lubricants where temperatures may exceed 200°C for extended periods.[12] At such high temperatures, conventional VDF-containing fluoroelastomers and TFE/P elastomers may swell excessively in heat-resistant lube oils so that o-ring seals may overfill standard grooves, extrude, and break up. Perfluoroelastomer compounds such as Kalrez® 4079 undergo little swell in such fluids, and are resistant to temperatures up to 316°C.

197

For the pharmaceutical industry, a number of perfluoroelastomer compounds have been designed to minimize contamination from filler particles, and to withstand sterilization in steam. Usually, these are white-filled peroxide-cured compounds such as Kalrez® 2037 or Chemraz® SD585. The semiconductor fabrication industry is a major application area for perfluoroelastomer seals, and many compounds have been, and continue to be, developed for various semiconductor fabrication processes. Each new generation of semiconductor fabrication lines requires better seal performance, especially for service life in aggressive environments and for cleanliness. Perfluoroelastomer parts’ suppliers offer special compounds finished and packaged under clean room conditions. Semiconductor fabrication involves plasma and gas deposition, thermal, and wet processing operations, each with different temperature ranges and environments. [13] Plasma processes include etching and ashing in fluorine or oxygen plasmas at temperatures up to 250°C. Gas deposition processes are carried out in a number of plasmas or reactive gas mixtures at temperatures up to 250°C, often under high vacuum. Seals must exhibit very low weight loss, particle generation, and outgassing under severe conditions. Thermal processes are carried out at 150°C to 300°C, and include oxidation diffusion furnaces, rapid thermal processing, and infrared lamp annealing. Seals must have excellent thermal stability with resistance to acidic or basic gases, along with low outgassing and particle generation. Wet processing includes wafer preparation, cleaning, and rinsing; etching; photolithography developing and rinsing; stripping; and copper plating operations. Maximum temperatures for these operations are in the range of 100°C to 180°C. Seals must be resistant to a variety of aggressive fluids including organic and inorganic acids, aqueous bases, and amines. Perfluoroelastomer compound recommendations are listed in Table 8.6 for these processes based on bulletins from DuPont Dow[13] for Kalrez® and from Greene, Tweed for Chemraz® 513,[14] 550,[15] 571,[16] 639,[17] and 655.[18] The preferred compounds listed generally meet the most stringent requirements for service in the process indicated, while alternative choices may give adequate service in situations with less severe environmental resistance or cleanliness requirements. The listing is not comprehensive; many other compounds are used, and new offerings are expected for this highly competitive industry.

Table 8.1 Chemical Resistance: FFKM Fluoroelastomer[1]

Reagent

Reagent Note

Cone, Temp. Time PDL % Volume Ways) Rating Change (0C) (%)

Abietic Acid

100

6

<10

Acetaldehyde Acetamide Acetanilide Acetic Acid

100 100 100 100 100 100 100 23 100

8 8 8 8 8 8 8 9 8

<10 <10 <10 <10 <10 <10 <10 2 <10

8 8 8 8 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

glacial

Acetic Anhydride Acetoacetic Acid Acetone Acetone Cyanohydrin Acetonitrile Acetophenetidin Acetophenone Acetotoluidide Acetyl Bromide Acetyl Chloride Acetylacetone Acetylene Acetylene Tetrabromide Acetylene Tetrachloride Acetylsalicylic Acid Acids

100 100 100 100 100 100 100 100 100 100 100 100. 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 1OQ 100 . 100 100 1OQ 100 100 100 100

mixed non organic organic

Aconitic Acid Acridine Acrolein Acrylic Acid Acrylonitrile Adipic Acid Aircraft Turbine Oils Alcohols Alkanes Alkanesulfonic Acid Alkenes Alkyl Acetone Alkyl Alcohol Alkyl Amine Alkyl Arylsulfonates Alkyl Arylsulfonics Alkyl Chloride Alkyl Sulfide Alkylbenzenes Alkylnaphthalenesulfonic Acid Allylidene Diacetate Alum Aluminum Acetate Aluminum Bromide Aluminum Chlorate Aluminum Chloride Aluminum Ethylate Aluminum Fluoride Aluminum Fluosiiicate Aluminum Formate Aluminum Hydroxide Aluminum Linoleate Aluminum Nitrate Aluminum Oxalate Aluminum Phosphate Aluminum Potassium Sulfate Aluminum Salts Aluminum Sodium Sulfate Aluminum Sulfate Amines Amino Phenol Aminoanthraquinone Aminoazobenzene

denatured

olefin hydrocarbons

too 100 100 100 100 too

:

100 100 1OO 100 100 100 100 100 100 100 100 100 100

7

a 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 S 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 . 8 8 8

a 8 8 8 8 8 8 8 8 8 8

Resistance Note

Material Note

Httle/nc- effect, severs opndit. may cause sk swell/prop, toss

DuPont Kalrez (FFKM)

little/no effect, severe condit. may cause si. swell/prop, loss

M

a

a

it

a

«

it

tt

«

it

K «

if U

(t

tl it

Ii

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Aminobenzenesulfonic Acid Aminobenzoic Acid Aminobenzoic Acid (p-) Aminoethylethanolamine Aminopyridine Aminosalicylic Acid Aminosalicylic Acid (p-) Ammonia

anhydrous gas, hot

Acetate Arsenate Benzoate Bicarbonate Bifluoride Bisulfite Bromide Carbamate Carbonate Chloride Citrate Dichromate Diphosphate Fluoride Fluosilicate Formate Hydrogen Fluoride Hydroxide Iodide Lactate Metaphosphate Molybdate Nitrate Nitrite Oxalate Perchlorate Perchloride Persulfate Phosphate

sal ammoniac

concentrated

dibasic monobasic tnbasic

Ammonium Phosphite Ammonium Picrate Ammonium Polysulfide Ammonium Salicylate Ammonium Salts Ammonium Sulfamate Ammonium Sulfate Ammonium Sulfate Nitrate Ammonium Sulfide Ammonium Sulfite Ammonium Thiocyanate Ammonium Thioglycolate Ammonium Thiosulfate Ammonium Tungstate Ammonium Valerate Amyl Acetate Amyl Alcohol Amyl Borate Amyl Butryate Amyl Chloride Amyl Chloronaphthalene Amyl Cinnamaldehyde Amyl Laurate Amyl Mercaptan Amyl Naphthalene Amyl Nitrate Amyl Nitrite

Temp, Time 0

( C)

100

gas, cold

Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium Ammonium

Cone. (%)

1Q0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 1Q0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 1GO 100 100 100 100 100 1Q0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

(days)

PDL % Volume Rating Change 8

<10

a

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

8

a 8 8 B 8 8 S 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

Resistance Note

Material Note

littfe/no effect, severe condit. may cause si. swell/prop, toss

DuPont Kalrez (FFKM)

M it (I

U U

it

H

U

44

a

«

a

44

44

M ti

U

it

a a U

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp, Time W XSL (days)

PDL % Volume Rating Change

Resistance Note

Material Note DuPont Kalrez (FFKM)

Amyl Phenol

100

8

<10

littte/no effect, severe condit. may cause sf. swell/prop, loss

Amyl Propionate Anderol L774 Aniline

too 100 100 100 100 100 100

e

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

U

Aniline Aniline Aniline Aniline Animal

Hydrochloride Hydrochlorine Sulfate Sulfite Fats

Tenneco Chemicals dyes

8 6 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 6

too lard

100

too Animal Oils Anisole Anisoyl Chloride Ansul's Ether Anthracene Anthranilic Acid Anthraquinone Antifreeze

100

too too 100 100

too ethylene glycol; Prestone solutions

100 100 1Q0

too too

Antimony Chloride Antimony Pentachloride Antimony Pentafluoride

100

Antimony Tribromide Antimony Trichloride Antimony Trifluoride

100

too

ASTM ASTM ASTM ASTM

Oil No. 4 Reference Fuel A Reference Fuel B Reference Fuel C

Aurex 256 Azobenzene Barium Carbonate Barium Chlorate Barium Chloride Barium Cyanide Barium Hydroxide Barium Iodide Barium Nitrate Barium Oxide Barium Peroxide

too 100 gas Monsanto

U

too 100 100 100

too 100 100 100 100 100 100 100

too 100 100 100

too lubricating oil

100 23 100 100 100 100

50% isooctane, 50% toluene

too 100

too Mobil Corp.

aqueous

100 100 100

too too too 100 100

too

<10 <10

a

<10

8

100

Aqua Regia Arachidic Acid Argon Aroclor 1248 Aroclor 1254 Aroclor 1260 Arsenic Acid Arsenic Oxide Arsenic Trichloride Arsenic Trioxide Arsenic Trisulfide Arsenites Arsine Aryl Orthosilicate Ascorbic Acid Askarel Aspartic Acid Asphalt ASTM Oil No. 1 ASTM Oil No. 2 ASTM Oil No. 3

8 8

7

H U

Ii

littte/no effect, severe condit. may cause si. swell/prop, loss

may cause si. visible swell/loss ol physical props,

6

100

Antimony Trioxide

a

may cause si. visible swell/loss of physical props.

100

Antimony Sulfate

(i

<10

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 9 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 2 <10

8 8 8 8

<10 <10 <10 <10

8 8 8 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Ktlte/no effect, sevBra condit. may cause si. swell/prop, loss

U

a M

« a

it

(( K

littte/no effect, severe eondif, may cause si. swell/prop, loss

If

U H

U

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone, Temp. (%) (0C)

PDL

% Volume Change

Resistance Note

Material Note

8

<10

little/no effect, severe condit. may cause si. swell/prop, loss

DuPont Kalrez (FFKM)

8 8 8 8 8 8 8 8 9 8

<10 <10 <10 <10 <10 <10 <10 <10 3 <10

100 100 100 1QO 100 100 100 100 100 1QO 100 100 100 100 100 100 100 100 100 100 100 10Q 100 100 100 100 100 100 100 100 100 100 100 100 100 10Q 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100 100

6 8

<10

littfe/no effect, severe condit. may Cause sL swell/prop, loss

100 1OO 100 100

8 8 8 8

<10 <10 <10 <10

44

Time

Ways) Rating

Barium Polysulfide 100

Barium Salts Barium Sulfate Barium Sulfide Beet Sugar Liquors Benzaldehyde Benzaldehydedisulfonic Acid Benzamide Benzanthrone Benzene Benzene Hexachloride Benzenesulfonic Acid Benzidine Benzidine 3-Sulfonic Acid Benzil Benzilic Acid Benzocatechol Benzoic Acid Benzoin Benzonitrile Benzophenone Benzoquinone Benzotrichloride Benzotrifluoride Benzoyl Chloride Benzoyl Peroxide Benzoylsufonilic Acid Benzyl Acetate Benzyl Alcohol Benzyl Benzoate Benzyl Bromide Benzyl Butyl Phthalate Benzyl Chloride Benzyl Phenol Benzyl Salicylate Benzylamine Beryllium Chloride Beryllium Fluoride Beryllium Oxide Beryllium Sulfate Bismuth Carbonate Bismuth Nitrate Bismuth Oxychloride Bittern Blast Furnace Gas Bleach

aqueous

ligroine

lime bleach solutions

Borax Bordeaux Boric Acid Boric Oxide Borneol Bornyl Acetate Bornyl Chloride Bornyl Formate Boron Hydride Boron Phosphate Boron Tribromide Boron Trichloride

solution, sodium borate mixture

Boron Trifluoride Boron Trioxide Brake Fluids

automotive Wagner 21B

Brines Bromic Acid

1QO 100 100 100 100 100 100 100 23 100

7

K

a

« a u little/no effect, severe condit may cause sJ. swell/prop. loss « U

I*

U H

a U U

a

U

a tt it

« U

M

a a

U

44

u

a

a a « a a it

may cause s i visible swell/loss 6f physical props, ii

«

U

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Bromine

anhydrous

100

a

<10

bromine water

100

8

<10

Bromine Pentafiuoride

100

6

Bromine Trifluoride Bromobenzene

100 100

6 8

Bromobenzene Cyanide Bromobenzylphenyl Ether (p-) Bromoform Bromomethane Bromotoluene Brucine Sulfate Bunker Fuel C Butadiene Butane Butanediol Butyl Acetate Butyl Acetyl Ricinoleate Butyl Acrylate Butyl Alcohol Butyl Alcohol (sec-) Butyl Alcohol (tert-) Butyl Benzoate Butyl Butyrate Butyl Carbitol Butyl Catechol (tert-) Butyl Cellosolve Butyl Cellosolve Acetate Butyl Chloride Butyl Ether Butyl Glycolate Butyl Lactate Butyl Laurate Butyl Mercaptan Butyl Mercaptan (tert-) Butyl Methacrylate Butyl Oleate Butyl Oxalate Butyl Paracresol Butyl Peroxide (di-tert-) Butyl Phenol Butyl Stearate Butylamine Butylbenzoic Acid Butylene Butyraldehyde Butyric Acid Butyric Anhydride Butyrolactone Butyryl Chloride Cadmium Chloride Cadmium Cyanide Cadmium Nitrate Cadmium Oxide Cadmium Sulfate Cadmium Sulfide Calcium Acetate

100 100 1OQ 100 100 100 100 100 100 100 100 100 100 100 1OQ 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 1OQ 100 100 100 100 100 100 100 100 100 100 1OO

8 8 8

Calcium Arsenate

100

a

<10

Calcium Calcium Calcium Calcium Calcium Calcium Calcium Calcium

1OQ 100 IQO 100 100 100 100 100

8

<10 <10 <10 <10 <1O <10 <10 <10

Benzoate Bicarbonate Bisulfide Bisulfite Bromide Carbide Carbonate Chlorate

methyl bromide

fuel oil

butanoi

Union Carbide

Cone, Temp, Time PDL % Volume (days) Rating Change (0C) (%)

a 8 6

a 8 8

a a a a a 8

a 8

a a a 8 a 8

a a a a a a a a a a a 8

a 8

a a a a a 8 a a a a a 8

a a a

a a a a 8 8

a

Resistance Note

Material Note

tittte/no effect, severe condtt. may cause si. swell/prop, loss

DuPont Kalrez (FFKM)

may cause si. visible swet!/loss Of physical props,

<10

littfe/no effect, severe condil. may cau$B sL swell/prop, loss

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10

U U K « it

U

ft

41

a 41 U

41

U U

U

U

41

may causa si. visible SW«II/IQSS of physical props, iittteftio effect, severe condit. may cause si, swell/prop, loss ti

4»

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone, Temp. Time

c%) Calcium Chloride Calcium Chromate Calcium Cyanamide Calcium Cyanide Calcium Fluoride Calcium Gluconate Calcium Hydride Calcium Hydrosulfide Calcium Hydroxide Calcium Hypochlorite Calcium Hypophosphite Calcium Lactate Calcium Naphthenate Calcium Nitrate Calcium Oxide Calcium Oxlate Calcium Permanganate Calcium Peroxide Calcium Phenolsulfonate Calcium Phosphate Calcium Phosphate Acid Calcium Propionate Calcium Pyridine Sulfonate Calcium Salts Calcium Stearate Calcium Sulfamate Calcium Sulfate Calcium Sulfide Calcium Sulfite Calcium Thiocyanate Calcium Tungstate Caliche Camphene Camphor Camphoric Acid Cane Sugar Capric Acid Caproaldehyde Caproic Acid Caproic Aldehyde Caprolactam Carbamate Carbazole Carbitol Carbolic Acid Carbon Bisulfide Carbon Dioxide Carbon Disulfide Carbon Fluorides Carbon Monoxide Carbon Tetrabromide Carbon Tetrachloride

Carbonic Acid Casein Castor Oil Caustic Lime Caustic Potash Caustic Soda Cellosolve Cellosolve Acetate Cellulose Acetate Cellulose Acetate Butyrate Cellulose Ether Cellulose Nitrate Cellulose Tripropionate Cellulube Cerium Sulfate

0

(days)

( C)

8

<10

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 9 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 4 <10

100 100 100 100 100 100 100 100 10O 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100

8

<10

100

liquors

Calgon phenol

sodium hydroxide Union Carbide

Tenneco Chemicals, phosphate esters

PDL % Volume Rating Change

100 100 100 100 100 100 100 100 100 100 100 100 100 100 1Q0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 23 100

7

Resistance Note

Material Note

littte/no effect, severs condlt. may cause si. swell/prop, loss

DuPont Kalrez (FFKM)

U U

U U

U

a

a U

u

a

4*

M

U

U

U

little/no eliect, severe condit. may cause si. swell/prop, toss

(I

U a

U a

U

W

K

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp, Time PDL % Volume {days) Rating Change (%) (0C) e

<10

100 100 100 100 100 100 100 100 100 100 100 100 100 100

S 8 8 8 8 8 8 8 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Chlorine Dioxide

100

8

<10

Chlorine Trifluoride

100

a

Chloroacetaldehyde Chloroacetic Acid

100

6

100

8

<10

100 100 100 100 100 100 23 100

8 8 8 8 8 8 9 8

<10 <10 <10 <10 <10 <10 <1 <10

100 100 100 100 100 100 100 100 100 100 ^ 100 100 100 100 1OQ 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100 100

6 8

100 100 100 100 100 100 IQO 100 100 100 10Q

8 8 8 8 8 8 8 8 8 8 6

100 100

6 8

<10

100 100

8 8

<10 <10

Cerous Chloride Cerous Fluoride Cerous Nitrate Cetane Cetyl Alcohol Cextrose Chaulmoogric Acid Chloral Chloramines Chloranthraquinone Chlordane Chloric Acid Chlorinated Solvents Chlorine

100

hexadecane

dry wet

Chloroacetone Chloroacetyl Chloride Chloroaminobenzoic Acid Chloroaniline Chlorobenzaldehyde Chlorobenzene

Chlorobenzene Chloride Chlorobenzene Trifluoride Chlorobenzochloride Chlorobenzotrifluoride Chlorobromomethane Chlorobromopropane Chlorobutane Chlorobutene Chlorododecane Chloroethane Chloroethane Sulfonic Acid Chloroethylbenzene Chloroform Chlorohydrin

butyl chloride

Chloronitrobenzene Chloronitroethane Chlorooxyfluorides Chloropentafluoroethane Chlorophenol Chiorophenol (p-) Chloropicrin Chloroprene Chlorosilanes Chlorosulfonic Acid Chlorotoluene Chlorotoluene Sulfonic Acid Chlorotoluidine Chlorotrifluoroethylene Chlorotrifluoromethane Chloroxylenol Chloroxylol Cholesterol

Freon 115, Dupont

chlorobutadiene

sulfuric chlorohydrin

CTFE Freon B, Dupont

7

Resistance Note

Material Note

littte/no stfect, severe condit. may cause si. swell/prop, loss

DuPont Kalrez (FFKM)

U

may cause si. visible swell/loss Oi physical props, littte/no effect, severe condit may cause sL sw&ll/prop. foss may causa si. visible swell/loss of physical props.

e

little/no effect, severe condit. may cause st. swell/prop, toss

a

little/no effect, severe condit, may cause sL swell/prop, toss

U W

(I U

a

«

U

M

may cause si. visible swell/loss of physical props.

<10

little/no effect, severe condit. may cause si. swell/prop, toss

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10

U

may cause si. visible swell/loss of physical props. Jittte/no effect, severe condit may cause $1 swell/prop, loss U

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp, Time PDL % Volume (days) Rating Change (%)

Chrome Alum

100

6

<10

Chromic Acid Chromic Chloride Chromic Fluorides Chromic Hydroxide Chromic Nitrates Chromic Oxide Chromic Phosphate Chromic Sulfate Chromium Potassium Sulfate Chromyl Chloride Cinnamic Acid Cinnamic Alcohol Cinnamic Aldehyde Citric Acid Clorox Coal Tar Cobaltous Acetate Cobaltous Brimide Cobaltous Chloride Cobaltous Linoleate Cobaltous Naphthenate Cobaltous Sulfate Coconut Oil Cod Liver Oil Codien Coke Oven Gas Copper Acetate Copper Ammonium Acetate Copper Carbonate Copper Chloride Copper Cyanide Copper Gluconate Copper Naphthenate Copper Nitrate Copper Oxide Copper Salts Copper Sulfate Corn Oil Cottonseed Oil Creosote Cresol Cresol (m-) Cresol (o-) Cresylic Acid Crotonaldehyde Crotonic Acid Crude Oils

1QO 100 100 100 100 100 1Q0 100 100 100 100 100 1Q0 100 100 100 100 100 100 100 100 100 100 100 100 100 1Q0 100 100 100 100 100 100 100 100 100 100 100 1QO 100 100 100 100 100 100 100 1QO 100 1QO 100 100 100 1QO 100 100 100 100

3 8 8 8 8 3 8 8 8 8 8 3 8 8 8 3 8 3 8 3 8 3 8 3 8 8 8 3 8 3 3 3 8 3 8 3 8 3 8 3 3 3 8 8 8 3 3 3 8 3 8 8 8 3 3 8 3 3

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

g 3

<1 <10

Cumaldehyde Cumene Cumene Hydroperoxide Cutting Fluids Cyanamide Cyanides Cyanoacetic Acid Cyanogen Cyanogen Chloride Cyanohydrin Cyanuric Chloride Cyclohexane

alum

Chlorox

coal tar methyl phenol metacresol

sour crude

isopropylbenzene cutting oils

gas

a

too 1Q0 23 100

7

Cyclohexanone Cyclohexene

100 100

1 8

<10

Cyclohexyl Alcohol Cyclohexylamine Cyclohexylamine Carbonate Cyclohexylamine Laurate

1OQ 100 100 100

8 8 8 8

<10 <10 <10 <10

Resistance Note

Material Note

fiHFe/no effect, sever? condit. may cause $1. swell/prop, loss

m

U

U

tt it H

«

it

it

a

M

U W

U

DuPont Kalrez (FFKM) it U U

a U

it 4«

U

U

it tt
U

it 4« «

little/no effect, severe condil. may cause $U swell/prop. loss not suitable for service liMe/no effect, severe condit, may cause si. swell/prop, toss

(Cont'd.) uU

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone:. Temp. 4 ( C) (%)

Time (days)

PDL % Volume Rating Change

Cyclopentadiene

100

8

<10

Cyclopentane Cyclopolyolefins Cymene (p-) DDT

100 100 100 100

8 8 8 8

<10 <10 <10 <10

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 1OQ 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100

8

<10

100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Dicyclohexylamine

100

8

<10

Dicyclohexylammonium Nitrate Dieldrin Diesel Fuels Diethanolamine Diethyl Benzene Diethyl Carbonate Diethyl Ether Diethyl Phthalate Diethyl Sebacate Diethyl Sulfate Diethylamine Diethylaniline

100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 . 8 6 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Decalin Decane Detergents Developing Solutions Dextrin Dextro Lactic Acid Diacetone Diacetone Alcohol Dialkyl Sulfates Diallyl Ether Diallyl Phthalate Diamylamine Diazinon Dibenzyl Dibenzyl Ether Dibenzyl Sebecate Diborane Dibromoethane Dibromoethylbenzene Dibutyl Cellosolve Adipate Dibutyl Ether Dibutyl Methylenedithio Glycolate Dibutyl Phthalate Dibutyl Sebacate Dibutyl Thioglycolate Dibutyl Thiourea Dibutylamine Dicarboxylic Acid Dichloroacetic Acid Dichloroaniline Dichlorobenzene (o-) Dichlorobenzene (p-) Dichlorobutane Dichlorobutene Dichlorodifluoromethane Dichlorodiphenyldichloroethane Dichloroethane Dichloroethylene Dichlorofluoromethane Dichlorohyrin Dichloroisopropyl Ether Dichloromethane Dichlorophenol Dichlorophenoxyacetic Acid Dichloropropane Dichloropropene Dichlorosilane Dichlorotetrafluoroethane

isopropyltoluene dichlorodiphenyltrichloroeth ane Dupont solutions

sym-Diphenylethante

Union Carbide

aliphatic

Freon 12, Dupont DDD

Freon 2 1 , Dupont

methylene chloride

Freon 114, Dupont

diesel oil DEA

Resistance Note

Material Note

little/no effect, severe condit. may cause si. swell/prop, toss U

DuPont Kalrez (FFKM)

a U tt U

H it

U

»

U U

K U

Il U

U

U

K a

a

u

K

44

may cause si, visible swell/loss of physical props. little/no effect severe condit. may cause si. swell/prop, loss Il

may cause si. visible swell/loss of physical props. iittfe/no effect, severe condtt. may cause si. swell/prop, toss

U

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp, Ttoie PDL % Volume Ways) Hating Change (%) 0

Resistance Note

Material Note

( C)

Diethylene Glycol Diethylenetriamine Difluorochloroethane Difluorodibromomethane Difluorodichloromethane

100 DETA 1QO

too Freon 12, Dupont

100 100

Difluoroethane

100

Diglycol Chloroformate Diglycolic Acid Dihydroxydiphenylsulfone Diisobutyl Ketone Diisobutylcarbinol Diisobutylene Diisopropyl Benzene Diisopropyl Ketone Diisopropylidene Acetone Dimethyl Disulfide Dimethyl Ether Dimethyl Formaldehyde Dimethyl Phenyl Carbinol Dimethyl Phenyl Methanol Dimethyl Phthalate Dimethyl Sulfoxide Dimethyl Terephthalate Dimethylacetamide Dimethylamine Dimethylaniline Dimethylformamide Dimethylhydrazine Dinitrochlorobenzene Dinitrogen Tetroxide Dinitrotoluene Dioctyl Phthalate Dioctyl Sebacate Dioctylamine Dioxane Dioxolane Dipentene Diphenyl Diphenyl Oxide Diphenylamine Diphenylene Oxide Diphenylpropane Dodecylbenzene Dowanol P Dowtherm Dry Cleaning Fluids Epichlorohydrin Erucic Acid Ethane Ethers Ethyl Acetate

DMDS methyl ether, monomethyl ether

DMSO DMT DMA xylidine DMF

DNT

biphenyl/phenylbenzene diphenyl ether DPA

mixture, Dow Chemical fluids, Dow Chemical

Ethyl Aluminum Dichloride Ethyl Benzene Ethyl Benzoate Ethyl Bromide Ethyl Butyrate Ethyl Cellosolve Ethyl Cellulose Ethyl Chloride Ethyl Chlorocarbonate Ethyl Chloroformate

Union Carbide

<10

8 8 8

<10 <10 <10

<10

100 100 100 100 100 100 100 100 100 100 100

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

1QO 100 100 100 100 100 100 100 100 100 100 100 100 100 IQO 100 100 100 100 100 100 100 1OQ 100 100 100 100 100 100 100 100 100 1QO 23 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 9 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 3 <10

8 8 9 8

<10 <10 0 <10

8 8 8 8 8 8 8 8 $ 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100 100 100 100 100 100 100 100 100 100

7

7

IMIe/no effect, severe condit. may cause si. swelt/prop. toss it

may cause s i visible swell/loss of physical props,

6 8 $ 8 8 8 8 8 $ 8 8 8 8

100 100 23 100

Ethyl Acetoacetate Ethyl Acrylate Ethyl Alcohol

8

ljMe/m> *tim, seven? condft. may cause si. swell/prop, loss « it 41 « 44

it

a U

44

U

u U

a

DuPont Kalrez (FFKM)

U

U

« 4» u

M U a

4i a 44

U U

44 U

44 U

U it

4i U-

littte/no effect, severe condiL may cause si. swell/prop, toss it

liWe/no effect, severe condit. may cause si. swell/prop, foss

44.

U «

44

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp, Time 0

( C)

PDL % Volume Rating Change

Resistance Note

Material Note

littte/no effect, severe ppndit. may cause si. swell/prop, loss

DuPont Kalrez (FFKM)

100

$

<10

1QO 100 100 100 100 100 100 100 100 100 100 100 100 100 1QO 100 100 100 100 100 1QO 100 100 . 23 100

8 8 8 a 8 8 8 8 a 8 3 8 a 8 8 8 S 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100 100 1QO 10O 1OQ 100 1OQ 100 1QO 100 100 100 100 100 1QO 100 1QO 100 1OQ 100 1OQ 100

8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Fluorobenzene

100

8

Fluorocarbon Oils

1OQ

6

100 100

6 8

100 1OQ 100 100 100 100 .

6 8 $ a $ a

<10 <10 <10 <10 <10

100

8

<10

Freon 113

100

a

may cause si. visible swell/loss of physical props,

Freon Freon Freon Freon

100 100 100 100

e

V

6

it

Ethyl Ether Ethyl Formate Ethyl Hexyl Alcohol Ethyl Lactate Ethyl Mercaptan Ethyl Nitrite Ethyl Oxalate Ethyl Pentachlorobenzene Ethyl Pyridine Ethyl Silicate Ethyl Stearate Ethyl Valerate Ethylamine Ethylcyclopentane Ethylene Ethylene Chloride Ethylene Chlorohydrin Ethylene Cyanohydrin Ethylene Dibromide Ethylene Dichloride Ethylene Glycol Ethylene Hydrochloride Ethylene Oxide Ethylene Trichloride Ethylenediamine

Ethyleneimine Ethylmorpholine Ethylsulfuric Acid Fatty Acids Ferric Acetate Ferric Ammonium Sulfate Ferric Chloride Ferric Ferrocyanide Ferric Hydroxide Ferric Nitrate Ferric Sulfate Ferrous Ammonium Citrate Ferrous Ammonium Sulfate Ferrous Carbonate Ferrous Chloride Ferrous Iodide Ferrous Sulfate Ferrous Tartrate Fish Oils Fluoboric Acid Fluorinated Cyclic Ethers Fluorine

Fluorolube Fluorophosphoric Acid

aqueous

aqueous U

fluoboric acid

liquid

Occidental Chemical

Fluosilicic Acid Fluosulfonic Acid Formaldehyde Formamide Formic Acid Freon 11 Freon112

114 114B2 115 116

Dupont

Dupont chloropentafluoroethane Dupont

7

8 S 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

a

(i

K

W

U

U

H U

little/no effect, severe condit. may cause si. swell/prop, loss

a

«

«

(( U

a U

« U

a U

may cause $1. visible swell/loss of physical props.

<10

IHtttfno effect, severe eontfil may cause sL swell/prop, toss may cause si. visible swefI/loss of physical props. U

<10

Ijttte/no tffect, severe oondit. may cause si. s we If/prop, toss it Vl it

may cause si. visible swell/loss of physical props. littte/no effect, severe condit. may cause si. swell/prop, loss

«

a

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone, Temp, (%) 0

Time (days)

( C)

Freon 12

POL Rating

% Volume Change

6 100

Freon 13 Freon 13B1 Freon 14 Freon 142B Freon 152B Freon 21 Freon 218 Freon 22

tetrafluoromethane Dupont it

1QO

e

«

6 6 8

<10 <10

tt

Dupont

100

S

chlorodifluoromethane

100

6

100

8

<10

1Q0 100 100 100

8 8 8 6

<10 <10 <10

Freon BF

tetrachlorodifluoroethane

100

8

<10

Dupont

100 100

8 6

<10

Freon MF Freon TA Freon TC

100 100 100

€ 6 8

Freon TF

100

6

100

8

<10

100 100 100 100 100 100 100 100 100 100 100 23 100

8 8 8 8 8 8 8 8 8 8 8 9 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 2 <10

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 . 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Freon TP35 Freon TWD602 Fuel Oils Fuels Fumaric Acid Furan Furfural Furfuryl Alcohol Furoic Acid Fyrquel Gallic Acid Gasoline

Dupont

aromatic furfuran furfuraldehyde

Stauffer Chemical

liquefied, LPG producer

Gelatins Glaubers Salt Gluconic Acid Glucose Glues Glutamic Acid Glycerin Glycerol Chlorohydrin Glycerol Dichlorhydrin Glycerol Triacetate Glycerophosphoric Acid Glyceryl Phosphate Glycidol Glycol Ether Glycolic Acid Glycols Glycoxylic Acid Green Sulfate Liquor Halothane Halowax Oil Helium Heptachlor Heptachlorobutene Heptaldehyde

glycerol

glycol monoether

Koppers

heptanal

DuPont Kalrez (FFKM)

6

Dupont

Freon TMC

littte/no effect, sever? condit. may cause si. swell/prop, toss

e

too 100 too 100 100 100

Freon 23 Freon 31 Freon 32 Freon 502

Freon C316 Freon C318

Material Note

6

Dupont bromotrifluoromethane

Resistance Note

100 100 100 100 too 100 100 100 1OQ 100 100 100 too 100 100 100 too 100 100 100 100 100 100 100 too 100

7

HttfB/no effect, severs condii. may cause si. swell/prop, toss

may cause si. visible swell/loss of physical props, little/no effect, severe condit may cause $1, swell/prop, loss

may cause si. visible sweit/loss of physical props, littte/no effect, severe condit, may cause si. swell/prop, toss

may cause si. visible swell/loss of physical props.

<10

little/no effect, severe condit. may cause a I. swell/prop, loss may cause $] r visible swell/loss of physical props. litHe/no effect, severe condit. may cause si. swell/prop, toss

littte/no effect, severe condiL may cause si, swell/prop, loss

U

a

U

« U

a

a a « U 41

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone, Temp, Time PDL % Volume {days) Rating Change W 0

Resistance Note

Material Note

littte/no effect, severe condtt. may cause si. swell/prop, toss

DuPont Kalrez (FFKM)

( C)

Heptane

8

<10

S 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10

100

Heptanoic Acid Hexachloroacetone Hexachlorobutadiene Hexachlorobutene Hexachloroethane Hexaethyl Tetraphosphate Hexafluoroethane

100 1OO 100 100 100 100 100

Freon 116, Dupont

100

8

<10

100 100 100 100 100 100 23 100

8 8 8 8 8 8 g 8

<10 <10 <10 <10 <10 <10 <1 <10

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100

8

<10

9 8

<5 <10

8 8 8 8 8 8 9 8

<10 <10 <10 <10 <10 <10 <1

Hydrooxycitronellal Hydroquinone

100 100 100 10Q 100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 4

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Hydroxyacetic Acid

100

8

<10

Hydyne Hypochlorous Acid lndole Insulin lodic Acid Iodine

100 100 100 100 100 100

8 8 8 8 8 8

<10 <10 <10 <10 <10 .<10

Hexafluoroxylene Hexaldehyde Hexamethyldisilizane Hexamethylene Hexamethylene Diammonium Adipate Hexamethylenediamine Hexamethylenetetramine Hexane Hexene Hexone Hexyl Acetate Hexyl Alcohol Hexylene Glycol Hexylresorcinol Hydraulic Oils

n-Hexaldehyde

cyclohexane

n-Hexene-1 methyl isobutyl ketone

petroleum base synthetic base

Hydrazine Hydrazine Dihydrochloride Hydrazine Hydrate Hydriodic Acid Hydroabietyl Alcohol Hydrobromic Acid 40

Hydrocarbons Hydrochloric Acid

cold hot

Hydrocyanic Acid Hydrofluoric Acid

23 100

concentrated

37 37

anhydrous cold, concentrated hot, concentrated

50

Hydrofluosilicic Acid Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen

gas

Bromide Chloride Cyanide Fluoride Iodide Peroxide Selenide Sulfide

anhydrous

anhydrous

90 wet, cold wet, hot

100 100 100 100 100 100 23 100

7

7

7

41 A

may cause s\. visible swell/loss ot physical props, HMe/no effect, severe tondit. may cause si. swell/prop. lo§s ««

«

liute/no effect, severe condit. may cause si. swell/prop, loss

U

a

U

may cause si. visible swell/loss of physical props.

<10

littte/no effect, severe condtt may cause si. swell/prop, ioss

U

little/no effect, severe condit. may cause si. swell/prop, loss U

M

nttte/no effect, severe condft, may cause si. swell^prop. loss

moder. to severe swell and/or loss of phys. props. littte/no effect, severe condit. may cause si. swell/prop, loss «

it

(Cont'd.]

Table 8.1 (Cont'd.)

Cone, Temp. Time (days) W

PDL Rating

Iodine Pentafluoride

100

6

lodoform lsoamyl Acetate

100 100

6 8

lsoamyl Butyrate lsoamyl Valerate lsoboreol lsobutane lsobutyl Acetate lsobutyl Alcohol lsobutyl Chloride lsobutyl Methyl Ketone lsobutyl Phosphate lsobutylene lsobutyric Acid lsocrotyl Chloride lsodecyl Alcohol lsododecane lsoeugenol lsooctane lsopentane lsophorone lsopropyl Acetate lsopropyl Alcohol lsopropyl Chloride lsopropyl Ether lsopropylacetone lsopropylamine

too

a

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 23 100

8

Reagent

Isovaleric Acid Jet Aircraft Fuels

Reagent Note

isopropanol

Fuel A JP 3 JP 4 JP 5 JP6

Kerosine Lacquers Lactic Acid

lacquer solvents

cold hot

Laurie Acid Lavender Oil Lead Lead Acetate Lead Arsenate Lead Azide Lead Bromide Lead Carbonate Lead Chloride Lead Chromate Lead Dioxide Lead Linoleate Lead Naphthenate Lead Nitrate Lead Oxide Lead Sulfamate Ligroin Lime Sulfur Lindol Linoleic Acid Linseed Oil Lithium Bromide Lithium Carbonate Lithium Chloride Lithium Citrate Lithium Hydroxide Lithium Hypochlorite

molten

benzine/nitrobenzine hydraulic fluids, Stauffer Chemical

brine

8

a

7

8 8 8 8 8 8 8 8 8 8 8 8 8 . 8 8 8 8 8 8 8 8 8 8 8 8 8 8 9 8

% Volume Change

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 2 <10

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8

8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10

8 8 8 8 8 8 8 8

e

Resistance Note

Material Note

may cause si. visible swell/loss of physical props.

DuPont Kalrez (FFKM)

little/no effect, severe contfll may cause s i , swell/prop, loss

U

it «

WWeIm effect, severe condit. may cause si. swell/prop, toss

a W M

U

M

«

U

4»

it

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp, Time PDL % Volume (days) Rating Change (%) 0

Resistance Note

Material Note

little/no effect, severe condit. may cause si. swell/prop, loss

DuPont Kalrez (FFKM)

( C)

Lithium Nitrate Lithium Nitrite Lithium Perchlorate Lithium Salicylate Lithopone Lubricants

Mobil 254 Mobiljet Il

Lubricating Oils

petroleum base synthetic base

Lye Magnesium Chloride Magnesium Hydroxide Magnesium Salts Magnesium Sulfate Magnesium Sulfite Magnesium Trisilicate Malathion Maleic Acid Maleic Anhydride Malic Acid Mandelic Acid Manganese Acetate Manganese Carbonate Manganese Dioxide Manganese Gluconate Manganese Hypophosphite Manganese Linoleate Manganese Naphthenate Manganous Chloride Manganous Phosphate Manganous Sulfate Mannitol MDI Mercaptan Mercaptobenzothiazole Mercuric Acetate Mercuric Cyanide Mercuric Iodide Mercuric Nitrate Mercuric Sulfate Mercuric Sulfite Mercurous Nitrate Mercury Mercury Chloride Mercury Fulminate Mercury Salts Mesityl Oxide Metaldehyde Metanitroaniiine Metatoluidine Methacrylic Acid Methallyl Chloride Methane Methoxychlor Methyl Abietate Methyl Acetate Methyl Acetoacetate Methyl Acetophonone Methyl Acrylate Methyl Acrylic Acid Methyl Alcohol

aqueous methylene di-p-phenylene isocyanate

MBT

methanol

wood alchol

Methyl Methyl Methyl Methyl Methyl

Amyl Acetate Amyl Ketone Anthranilate Benzoate Butyl Ketone

8

<10

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 10Q 100 100 100 100 100 100 100 23 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 6 8 8 0 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <1O <10 <10 <10 <10 <10 <1O <10

6 8 8 8 8 8

<10 <10 <10 <10 <10 <10

100

100 100 100 100 100 100

7

<1 <10

U

U

U

(I

it

»

little/no effect, severe condit. may cause si. swell/prop,, toss

M U

a

{Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp, Time PDL % Volume Rating Change (%) 0

Resistance Note

Material Note

( C)

Methyl Butyrate Cellosolve Union Carbide

Methyl Methyl Methyl Methyl Methyl Methyl Methyl Methyl Methyl Methyl Methyl Methyl Methyl

Butyrate Chloride Carbonate Cellosolve Cellulose Chloride Chloroacetate Chloroformate Chlorosilanes Cyanide Cyclohexanone Cyclopentane Dichloride Ether

Union Carbide

acetonitrile

dimethyl ether dimethyl ether/monomethyl ether methyl ether

Methyl Ethyl Ketone

MEK <(

Methyl Methyl Methyl Methyl Methyl Methyl Methyl

Ethyl Ketone Peroxide Ethyl Oleate Formate Hexyl Ketone Iodide lsobutyl Carbinol lsopropyl Ketone

Methyl Lactate Methyl Methacrylate Methyl Oleate Methyl Pentadiene Methyl Phenylacetate Methyl Salicylate Methyl Sulfuric Acid Methyl Tertiary Butyl Ether Methyl Valerate Methylal Methylamine Methylaniline Methylene Bromide Methylene Chloride Methylene Iodide Methylglycerol Methylisocyanate Methylisovalerate Methylpyrroiidine Methylpyrrolidone Mil-L-23699 Mil-L-7808 Mineral Oils Molybdenum Oxide Molybdenum Trioxide Molybdic Acid Morpholine Motor Oils Mustard Gas Myristic Acid Naphtha Naphthalene Naphthalene Chloride Naphthalenesulfonic Acid Naphthalenic Acid Naphthalonic Acid Naphthenic Acids Naphthylamine Natural Gas

2-Octanone

MBK

MTBEC

MMA

100 1QO 100 100 100 100 100 100 100 100 100 100 100 100 100 100 23 100 100 100 100 1OQ 100 100 100 1QO 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

too lubricants

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

7

e

<1O

8 8 8 8 $ 8 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10

8 9 8

<10 <1 <10

8 8 8 8 8 8 8 8 8 8 $ 8 8 8 8 8 $ 8 8 8 8 8 8 8 8 8 8 8 8 8 $ 8 8 8 8 8 8 8 8 8 $ 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <1O <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <1O <10 <10

littWno tfim, severs condtt. may cause si. swell/prop, toss U

4

a

« it H

«

a

It

a

MeIm eftat. severe conctrt. may cause si. swell/prop, loss

U

DuPont Kalrez (FFKM)

n

u n

a U U

«

u 41

«

a

a

U

(I

41 it if

a

U 44 M a U

a

(Cont'd.) sour (I

U(I W

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone, Temp, Time (K)

PDL Rating

% Volume Change

Resistance Note

Material Note

litt(e/no effect, severe condit. may cause si. swell/prop, loss

DuPont Kalrez (FFKM)

Neats Foot Oil

100

8

<10

Neon Neville Acid Nickel Acetate Nickel Ammonium Sulfate Nickel Chloride Nickel Cyanide Nickel Nitrate Nickel Salts Nickel Sulfate Nicotinamide Nicotinamide Hydrochloride Nicotine Nicotine Sulfate Niter Cake Nitric Acid

too 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 3 8

8 8 8 3 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10

100 100 .23 100

8 8 9 8

<10 <10 <1 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

aqueous

aqueous

aqueous niacinamide

inhibited, red fuming white fuming

0-50

50100

Nitroaniline Nitroaniline (p-) Nitrobenzene

a 8

a

7

it

«1

ii

a a (I

liltie/no effect, severe condit. may cause si. swell/prop, loss

Nitrobenzoic Acid Nitrobenzoic Acid (p-) Nitrocellulose Nitrochlorobenzene Nitrochloroform Nitrodiethylaniline Nitrodiphenyl Ether Nitroethane Nitrofluorobenzene Nitrogen Nitrogen Oxide Nitrogen Peroxide Nitrogen Tetraoxide

100 100 100 100 too 100 too 100 100 100 100 100 100

8 8 8 8 8 8 8 8 3 8 3 $ €

Nitrogen Trifluoride Nitroglycerin

100 100

6 8

<10

littte/no affect, severe condit. may cause si. swell/prop, loss

Nitroglycerol Nitroisopropylbenzene Nitromethane Nitrophenol Nitrophenol (p-) Nitropropane Nitrosyl Chloride Nitrosylsulfuric Acid Nitrothiophene Nitrotoluene Nitrotoluene (o-) Nitrous Acid Nitrous Oxide Nonane Octachlorotoluene Octadecane Octane Octyl Acetate Octyl Alcohol Octyl Chloride Octyl Phthalate Oleic Acid Oleum Oleyl Alcohol Olive Oil Orthochloroaniline Orthochloronaphthalene Orthochlorophenol

100 100 100 100 100 100 . 100 100 100 100 100 .

3 8 8 8 3 8 8 8 8 8 8 8 8 8 8 8 8 8 3 8 8 8 8 8 3 3 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

U

too 100 100 too n-Octane

fuming sulfuric acid

100 100 too 100 100 100 100 100

too 100 100 100 too

(I

H

a U

a H

may cause s i visible swell/loss of physical props. U

«t

it

a

U

H

U

U

a

it

Il «

{Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone. Temp. Time 0 (%) ( C) (days)

PDL Rating

% Volume Change

Resistance Note

Material Note

Orthophos Acid

Chevron Chemical

100

8

<10

littfe/no effect, severs condit. may cause si. swell/prop, toss

DuPont Kalrez (FFKM)

100 100 100 100 100 100 100 100 100 100 1QO 100 100 100 100 100 100 100 100 100 100 100 100

8 8 .8 8 8 S 8 8 8 8 8 8 8 8 8 8 8 8 8 8 $ 8 6

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Perchloric Acid

100

8

<10

Perchloroethylene

23 100

9 8

2 <10

Perfluorotriethylamine

100

6

100

8

<10

8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Oxalic Acid Oxygen

cold hot

Ozone Paint Thinners Palmitic Acid Paracymene Paraffin Paraformaldehyde Paraldehyde Parathion Peanut Oil Pectin Pelagonic Acid Penicillin Pentachloroethane Pentachlorophenol Pentaerythritol Pentaerythritol Tetranitrate Pentane Pentoxone Pentyl Pentanoate Peracetic Acid

liquor

liquid

Shell Chemical

Permanganic Acid Persulfuric Acid Petrolatum Petrolatum Ether Petroleum

Caro's acid

above 250 deg below 250 deg crude

Phenol Phenolic Sulfonate Phenolsulfonic Acid Phenyl Acetate Phenyl Benzene Phenylacetamide Phenylacetic Acid Phenylenediamine Phenylethyl Alcohol Phenylethyl Ether Phenylethyl Molonic Ester Phenylglycerine Phenylhydrazine Phenylhydrazine Hydrochloride Phenylmercuric Acetate Phorone Phosgene Phosphine Phosphoric Acid Phosphorous Phosphorous Oxychloride Phosphorous Trichloride Phthalic Acid Phthalic Anhydride Pickling Solutions Picoline (ot,k-) Picric Acid Pine Oil

carbolic acid

biphenyl/diphenyl

PDA phenetole

diisopropylidene acetone

20 45 molten

white

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

7

a 8 8 8

8 a 8 8 8 8 8 8 8 8 8 S 8 8 8 8 8 8 8 8 6 8 8 8

a 8 8 8 8 8 8

K

U

U

U

M

W

may cause si. visible swell/loss of physical props, littfe/no effect, severe condit. may cause si. swell/prop, loss

liltfe/no effect, seven? pondft. may cause s i . swell/prop, loss may cause si. visible swell/loss of physical props. littteVno effect, severe condit. may cause si, swell/prop, toss

U

U

it

U

U

41

«

a U

U

44

U

U

U

a 4* « U «

U

it

it

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent Note

Reagent

Cone.

Temp, (0C)

Pine Tar

100

Pinene Piperazine Piperidine Plating Solutions

chrome others

Polyethylene Glycol Polyglycerol Polyglycols Polyolefins Polyvinyl Acetate Potassium Potassium Acetate Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium

Acid Sulfate Alum Aluminum Sulfate Antimonate Bicarbonate Bichromate Bifluoride Bisulfate Bisulfite Bitartrate Bromide Carbonate Chlorate Chloride Chromate

Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium

Citrate Cuprocyanide Cyanate Cyanide Dichromate Diphosphate Ferricyanide Fluoride Glucocyanate Hydroxide Hypochlorite lodate Iodide Metabisulfate Metasilicate Nitrate Nitrite Oxalate Perchlorate Perfluoroacetate Permanganate Peroxide Persulfate Phosphate

emulsion molten

potassium monochromate

acid alkaline di/tri basic

Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium Potassium

Pyrosulfate Salts Silicate Sodium Tartrate Stannate Stearate Sulfate Sulfide Sulfite Tartrate Thiocyanate Thiosulfate Triphosphate

Time

% Volume Change

Resistance Note

Material Note

a

<10

little/no effect, severe condil may cause si. swell/prop, toss

DuPont Kalrez (FFKM)

U

PDL

«feys) Rating

IQO 100 100 100 100 100 100 100 100 100 1QO 100

8 8 8 8 8 8 S 8 6 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10

1 8

<10

100 100 100 100 100 100 100 100 100 100 100 1OQ 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 . 100 100 100 100 100 100 10Q 100 100 100 10Q 100 100 100

8 6 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

41 it

Ii

not suitable for service iittte/no effect, severe condit. may cause 31. swell/prop, loss

a

a

tt

a

U

it

a

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone, Temp, Time PDL % Volume Rating Change (%)

Propane

100

8

<10

Propionaldehyde Propionic Acid D ropionitrile Propyl Acetate Propyl Acetone Propyl Alcohol Propyl Nitrate Propyl Propionate Propylamine Propylbenzene Propylene Propylene Chloride Propylene Chlorohydrin Propylene Dichloride Propylene Glycol Propylene Oxide PydrauMOE Pydraul 115E Pydraul 230E Pydraul 29 ELT Pydraul 3OE Pydraul 312C

1QO 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

a

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Pydraul 5OE Pydraul 540C

100 100

1 8

Pydraul 65E Pydraul 9OE Pyranol

100 100 100

1 1 8

methyl butyl ketone 1-propanol

hydraulic fluid; Monsanto

Transformer Oil, GE

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 1 8

<10

<10 <10 <10 <10 <10 <10 <10

Pyrrole

100

8

<10

Pyruvic Acid Quinidine Quinine Quinine Bisulfate Quinine Hydrochloride Quinine Sulfate Quinine Tartrate Quinizarin Quinoline Quinone Raffinate Ramjet Fuel Rapeseed Oil Red Oil Resorcinol Rhodium Riboflavin Ricinoleic Acid Rosin RP 1 Saccharin Sal Ammoniac Salicylic Acid Sea Water Sebacic Acid Selenic Acid Selenious Acid Shellac Silane Silicate Esters

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 $ 8 8 8 $ 8 8 8 8 8 8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <1O <10 <1O <1O <1O <10 <10 <10 <10 <1O <10 <10 <10 <10 <10

RJ 1; MIL-F-25558 B MIL-H-5606

MIL-H-25576 C solution

littfe/no effect, severe condit. may cause si. swell/prop, toss

DuPont Kalrez (FFKM)

M

it

H

a

U

U

littte/no effect, severs eontffl may cause Sl. swe!l/prop. loss not suitable for service littfe/no effect, severe condit. may cause s i swell/prop, loss not suitable for service

8 8 8 8 8 8 €

pyrogallol

Material Note

not suitable for service

<10

100 100 100 100 100 100 100

Pyridine Pyridine Sulfate Pyridine Sulfonic Acid Pyrogallic Acid Pyroligneous Acid Pyrosulfuric Acid Pyrosulfuryl Chloride

Resistance Note

little/no effect, severe condit. may cause si. swell/prop, loss «

may cause si. visible swell/loss of physical props. little/no effect, severe condlt. may cause si. swell/prop, toss

u

a

it H

a

a


a U

{Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Silicon Fluoride Silicon Tetrachloride

Cone, (%)

Temp. (0C) 100

dry

1OO

Time

PDL

(days) Rating 8

% Volume Change

Resistance Note

<10

littfe/no effect, severe condit. may cause si. swell/prop, toss

6

may cause si. visible swell/loss of physical props.

100 100 100

6

Silicon Tetrafluoride Silicone Grease

8

<10

Silicone Oils Silver Bromide Silver Chloride Silver Cyanide Silver Nitrate Silver Sulfate Skydrol 500 Skydrol 7000 Soap Soda Ash Sodium Sodium Acetate

100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10

wet

Sodium Acid Bisulfate Sodium Acid Fluoride Sodium Acid Sulfate Sodium Aluminate Sodium Aluminate Sulfate Sodium Anthraquinone Disulfate Sodium Antimonate Sodium Arsenate Sodium Arsenite Sodium Benzoate Sodium Bicarbonate Sodium Bichromate Sodium Bifluoride Sodium Bisulfate Sodium Bisulfide Sodium Bisulfite Sodium Bitartrate Sodium Borate Sodium Bromate Sodium Bromide Sodium Carbonate Sodium Chlorate Sodium Chloride Sodium Chlorite Sodium Chloroacetate Sodium Chromate Sodium Citrate Sodium Cyanamide Sodium Cyanate Sodium Cyanide Sodium Diacetate Sodium Diphenylsulfonate Sodium Diphosphate Sodium Disilicate Sodium Ethylate Sodium Ferricyanide Sodium Ferrocyanide Sodium Fluoride Sodium Fluorosilicate Sodium Glutamate Sodium Hydride Sodium Hydrogen Sulfate Sodium Hydrosuifide Sodium Hydrosulfite Sodium Hydroxide Sodium Hypochlorite Sodium Hypophosphate Sodium Hypophosphite Sodium Hyposulfite Sodium Iodide

Monsanto; hydraulic fluid

solutions

molten

soda ash

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 1Q0 100 100 100 100 100 100 100 100 100 100 100 100 100

too 100 100 100 1OO 100 100 100 100 100 100 100 100 100 100 100 100 100

Material Note

a

a 8 8 8 8 8 1 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

little/no effect, severe condit. may causB sk sweltfprop. loss

« not stiftabte for service

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

littfe/no effect, severe condit, may cause $1, swell/prop, foss

U

a

U a

M

it


DuPont Kalrez (FFKM)

«

a

U

U

U

(Cont'd.) it

Table 8.1 (Cont'd.)

Reagent Note

Reagent

Cone, Temp, 0

TJme

PDL % Volume Rating Change

Resistance Note

Material Note

little/no effect, severe condit. may cause si swell/prop, loss

DuPont Kalrez (FFKM)

( C)

Sodium Lactate Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium Sodium

Metaphosphate Metasilicate Methylate Nitrate Oleate Orthosilicate Oxalate Perborate Percarbonate Perchlorate Peroxide Persulfate Phenolate Phenoxide Phosphate

Sodium Piumbite Sodium Pyrophosphate Sodium Resinate Sodium Salicylate Sodium Salts Sodium Sesquisilicate Sodium Silicate Sodium Silicofluoride Sodium Stannate Sodium Sulfate Sodium Sulfide Sodium Sulfite Sodium Sulfocyanide Sodium Tartrate Sodium Tetraborate Sodium Tetraphosphate Sodium Tetrasulfide Sodium Thioarsenate Sodium Thiocyanate Sodium Thiosulfate Sodium Trichloroacetate Sodium Triphosphate Solvesso 100 Solvesso 150 Sorbitol Soybean Oil Stannic Ammonium Chloride Stannic Chloride Stannic Tetrachloride Stannous Bisulfate Stannous Bromide Stannous Chloride Stannous Fluoride Stannous Sulfate Stauffer 7700 Steam

$

<10

1OO 100 100

8 8

too

S S 8 8 8

<10 <10 <10 <10 <10 <10 <10 <1O <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <1O <10 <10

100

sodium monophosphate

Exxon

aqueous

aqueous

Stauffer Chemical

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 *149 >149

Stearic Acid Stoddard Solvents Strontium Acetate Strontium Carbonate Strontium Chloride Strontium Hydroxide Strontium Nitrate Styrene Succinic Acid Sucrose Sulfamic Acid Sulfanilic Acid Sulfanilic Chloride Sulfanilimide Sulfite Liquors

white spirits

aqueous

solution

100 100 100 100 100 100 100 100 100 100 100 100 1OO 100 100

a

a 8

a 8 8 8 8 8 8 8

a 8 8 8 8 8

a 8

a 8 8 8 8 8 8 8 8 8 6 8

a 8 8 8 8 8

a 8 8 8 8 8 8 8

a 8

a 8 8 8 8 8

a 8 8 8 8 8

a

M U U U

a

Ii

a

# a a U a

tl

<4 U

U M U

U

K « M U

it H

U

U

a

it U

((

H

8

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone, Temp. Tfme PDL % Volume Bating Change (%) 0

Resistance Note

Material Note

HtHe/no 9ftect> severe pondit. may cause si. swell/prop, toss

DuPont Kalrez (FFKM)

( C)

Sulfonated Oils

8

<10

8

<10

100

Sulfonic Acid Sulfonyl Chloride

1Q0 100

Sulfur Sulfur Chloride Sulfur Dioxide

100 sulfur monochloride

dry liquid moist

Sulfur Hexafluoride Sulfur Trioxide Sulfuric Acid

20% oleum concentrated dilute fuming, 20% oleum

Sulfurous Acid Sulfuryl Chloride Tallow Tannic Acid Tar Tartaric Acid TDI Tellone Il Terephthalic Acid Terpineol Terpinyl Acetate Tetrabromoethane Tetrabromomethane Tetrabutyl Titanate Tetrachloroethylene Tetraethyllead Tetrafluoromethane

tannin bituminous

toluene diisocyanate Dow Chemical

Freon 14, Dupont

Tetramethylammonium Hydroxide Tetramethyldihydropyridine Tetraphosphoglucosate Tetraphosphoric Acid Therminol 55 Therminol 66 Therminol FR Thio Acid Chloride Thioamyl Alcohol Thiodiacetic Acid Thioethanol Thioglycolic Acid Thionyl Chloride Thiophene Thiophosphoryl Chloride Thiourea Thorium Nitrate Tin Ammonium Chloride Tin Chloride Tin Tetrachloride Titanic Acid Titanium Dioxide Titanium Sulfate Titanium Tetrachloride TNT

tetrahydronaphthalene, Dupont

Monsanto

thiofuran

trinitrotoluene

a

100

€ 6 8 8 € 8

100 100 100 100 100 100 100 100 100 100 100 1GO 100 1OQ 100 10Q 100 100 100 100 . 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 6

100

Tetralin

8

100 100 100 100 100 100

23

Tetrahydrofuran

100 100 1OQ 100 100 100 1QO 100 1OQ 100 1OQ 100 IQO 1OO 100 100 100 100 100 10O

may cause si. visible sweWloss of physical props.

&

7

9 8 8

a

too 1OO 100 100 100

8 8 8 8 8 6 8 8 8 8 8 8 8 8 8 8 8 8 8 6 8 8 €

1OQ

8

<10

little/no effect, severe condit. may cause si. swell/prop, loss

<10 <10 <10 <10 <10 may cause s i visible swell/loss of physical props,

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

little/no effect, severe condit. may cause si. swell/prop, loss

U

U

Cl

may cause $1. visible swell/loss of physical props.

<1 <10

iittte/rio effect, severe condit. may cause si. swell/prop, toss «

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

<1O

U U

«1 «

a

U

a

a a

a a « M «

U

a may cause si. visible swell/loss of physical props, little/no effect severe condit. may cause si. swell/prop, toss

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone, Temp, Time PDL % Volume ( 0 C) (days) Rating Change (%) 9 a

<1 <10

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

100

8

<10

100 100 100 100

8

8 8 6

<10 <10 <10

Tricresyl Phosphate

100

8

<10

Triethanolamine Triethyl Phosphate Triethylaluminum Triethylamine Triethylborane Triethylene Glycol Triethylenetetramine Trifluoroacetic Acid Trifluorochloroethylene

100 100 100 10Q 100 100 100 100 100

8 8 8 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10 <10 <10

Trifluoromethane

100

8

<10

Trifluorovinylchloride Triisopropylbenzylchloride Trimethylamine Trimethylbenzene Trimethylpentane Trioctyl Phosphate Triphenyl Phosphite Tripotassium Phosphate Trisodium Phosphate Tritium Tung Oil Tungsten Hexafluoride

100 100 1QO 100 1QO 100 100 100 100 100 100 100

8 8 8 8 8 8 8 8 8 8 8 6

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Tungstic Acid

100

8

<10

Turpentine Ucon

1QO 100

8

8

<10 <10

100

8

<10

1QO

8

<10

Toluene

Toluene Bisodium Sulfite Toluene Diisocyanate Toluenesulfonic Acid Toluenesulfonic Acid (p-) Toluenesulfonyl Chloride Toluidine Toluquinone Tolylaldehyde Transformer Oils Transmission Fluids

23 100

TDl

type A automatic

Triacetin Triaryl Phosphate Tribromomethylbenzene Tributoxyethyl Phosphate Tributyl Citrate Tributyl Mercaptan Tributyl Phosphate Tributylamine Trichloroacetic Acid Trichloroacetyl Chloride Trichlorobenzene Trichloroethane Trichloroethanolamine Trichloroethylene Trichlorofluoromethane

Freon 11, Dupont

Trichloromethane Trichloronitromethane Trichlorophenylsilane Trichloropropane Trichlorotrifluoroethane

UDMH Undecyclenic Acid

chloropicrin

Freon 113, Dupont

TEA

Freon 23, Dupont

china wood oil

lubricants/fluids, Union Carbide unsymmetrical dimethyl hydrazine

7

Resistance Note

Material Note DuPont Kalrez (FFKM)

ljttte/h« eitect^^eV^e (tondlL may cause si. swell/prop, toss

a

a

may cause si. visible swell/loss of physical props. liUte/no effect, severe condiX may cause si. swell/prop, loss

may cause $1. visible swell/loss of physical props. little/no effect, severe condit, may cause si. swell/prop, loss

a M

M

Il

may cause $1 visible sweN/loss of physical props, little/no effect, severe condit may cause sL swell/prop, loss

M U

U

may cause si. visible swell/loss Of physical props.

H

littte/no effect, severe COIKHI. may cause si. swell/prop, loss a

it

U

(Cont'd.)

Table 8.1 (Cont'd.)

Reagent

Reagent Note

Cone,

Temp.

Time .M.

PDL % Volume Hating Change

Undecylic Acid

100

8

Uranium Hexafluoride

100

6

Uranium Sulfate

100

3

<10

Uric Acid Valeric Acid Vanadium Oxide Vanadium Pentoxide Varnish Vegetable Oils Versilube F50 Vinegar Vinyl Acetate Vinyl Acetylene Vinyl Benzene Vinyl Chloride Vinyl Fluoride Vinylidene Chloride Vinylpyridine Vitriol Water

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

8 8 8 8 8 8

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

white cold deionized heavy hot

White Oil Wood Oil Xenon Xylene Xylidine Zeolites Zinc Acetate Zinc Ammonium Chloride Zinc Chloride Zinc Chromate Zinc Cyanide Zinc Diethyldithiocarbamate Zinc Dihydrogen Phosphate Zinc Fluorosilicate Zinc Hydrosulfite Zinc Naphthenate Zinc Nitrate Zinc Oxide Zinc Phenolsulfonate Zinc Phosphate Zinc Salts Zinc Silicofluoride Zinc Stearate Zinc Sulfate Zinc Sulfide Zirconium Nitrate

xylol

di-methyl aniline

too 100 100 100 100 100

too 100 100 100 100 100 100 100 100 100 100 100

too

a 8 8

e 8 8

a 8 8 8 3 8 8 8 8 8 3

8 8 8 8 8 8 3 8 6 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

<10

Resistance Note

Material Note

littte/no effect, severe condit. may cause si. swell/prop, toss

DuPont Kalrez (FFKM)

may cause sj. visible swell/loss of physical props, little/no effect, severe condit. may cause si. swell/prop, loss

it

a

41 it

it

it

it

44

44

U

M U U U U

44

Table 8.2 Chemical Resistance131

Compound Kalrez 6375

Kalrez 4079

Kalrez 2035

Aromatic/Aliphatic oils

++++

++++

++++

++++

Acids

++++

++++

++++

+++

Bases

++++

+++

+++

++++

Alcohols

++++

++++

++++

++++

Aldehydes

++++

+++

++++

++++

Amines

+++

+

++

++++

Ethers

++++

++++

++++

++++

Esters

++++

++++

++++

++++

Ketones

++++

++++

++++

++++

Steam/Hot water

++++

+

+++

+++

Strong Oxidizers

++

++

++

++

Ethylene Oxide

++++

X

++++

X

Hot Air

+++

++++

++

+++

Chemical Resistance to:

Kalrez 1050LF

Ratings: Excellent

Very Good

Good

Fair

Not Recommended

Table 8.3 Upper Continuous Service Temperatures for Perfluoroelastomer Compounds[5]

Cure

Upper Service Temperature, 0C

6375

Proprietary

275

4079

Triazine

315

2035

Peroxide

210

1050LF

Bisphenol

280

Kalrez Compound

Table 8.4 Tecnoflon PFR: Heat Aging Tecnoflon PFR 95191

181

PFR 94

Compound, phr

Luperco 10IXL peroxide

1.5

1.5

TAIC, 75% dispersion

2

-

ZnO

5

5

15

15

36

32

0.68

0.45

14.4

10.4

0.9 1.7

1.5 6.5

M100, MPa

11.5

7.7

TB, MPa

19.5

19.5

EB, %

145 78

205 73

-39 -15 +66 -1

+27 +11 -9 0

MT N-990 carbon black 0

Mooney Viscosity, ML-IO (121 C) 0

Rheology

ODR, 177 C, 3° arc ML, N-m MH, N-m ts2, minutes t'90, minutes Press cured (1700C), post cured (2000C)

Hardness, Shore A Heat aged 70 hours at 275°C M100, % change

Physical Properties

TB, % change EB, % change Hardness change, points Heat aged 70 hours at 2900C

+14 +2 -2 +1

M100, % change TB, % change EB, % change Hardness change, points

Table 8.5 Perfluoroelastomer Black Compounds for Chemical Processing Industry

Kalrez

Trade Name: Compound:

Chemraz

6375

7075

4079

1050

505

615

Mioo, MPa

7.2

7.6

7.2

12.4

7.5

T 8 , MPa

15.1

17.9

16.9

18.6

13.1

EB, % Hardness, Shore A

160

160

150

125

140

75

75

75

82

80

30

12

25

35

14

275

327

315

280

Typical Physical Properties

Compression Set, % (70 h/204°C) 0

Maximum Service Temperature, C

218

324

Table 8.6 Perfluoroelastomer Compounds for Semiconductor Applications

Trade Name Kalrez®'131 Chemraz Sahara Compound

8575

8085

++

+

8002

8475

6375UP

4079

513[14]

550[15]

5 7 1 [i6]

639[17]

655[18]

Process Evironment Plasma-etching/ashing

++

Gas deposition

+ +

++ ++

Thermal Wet Color

++

+ ++

+

++ +

++

White

Beige

Clear

White

Black

Black

White

Black

White

Ivory

Off-white

300

225

250

300

275

316

210

210

210

260

315

2.5

7.5

2.9

2.2

7.2

7.2

7.2

7.9

8.5

9.0

7.2

TB, MPa

15.1

16.9

11.0

12.1

10.7

15.1

12.9

EB, %

160

150

165

140

130

144

190

0

Max. service temp., C Physical properties M100, MPa

Hardness, Shore A

74

82

69

72

75

75

80

75

80

81

82

70 h/204°C

29

42

15

23

30

25

25

25

35

34

45

Supplier recommendations

++ Preferred for service + Alternative choice

226

FLUOROELASTOMERS HANDBOOK

REFERENCES 1. Chemical Resistance, Vol. 2: Elastomers, Thermosets and Rubbers, PDL Handbook Series, Chemical Resistance – FFKM Fluoroelastomer, Second Edition, pp. 255-279, William Andrew Inc., Norwich, NY (1994) 2. Chemical Resistance Guide, Technical Information, www.DuPontElastomers.com (2005) 3. Kalrez® SpectrumTM 6375 Perfluoroelastomer Parts, Technical Information, www.DuPont-Dow.com (2004) 4. Chemraz® Compounds for fluid handling, www.gtweed.com (2004) 5. Kalrez® Technical Information, www.DuPont-Dow.com (2004) 6. L. Ojakaar, US Patent 4,983,680, assigned to DuPont (January 8, 1991) 7. R. Ferro, V. Arcella, M. Albano, M. Apostolo, and I. Wlassics, “New Developments in Polymerization Technologies and Curing,” paper presented at International Rubber Conference, Manchester, UK (June 1999) 8. Tecnoflon PFR 94, Product Data Sheet, www.SolvaySolexis.com (2002) 9. Tecnoflon PFR 95, Product Data Sheet, www.SolvaySolexis.com (2002) 10. New High Temperature Perfluoroelastomer - Chemraz® 615, Fluid Handling Products bulletin US3230-013, www.gtweed.com (September 2002) 11. Physical Properties and Compound Comparisons, Kalrez® Technical Information Bulletin KZE-H6825400-F0203, DuPont Dow Elastomers (February 2003) 12. Elastomeric Seals and Their Testing in Aircraft Engine Lubricants, Kalrez® Technical Information Bulletin, DuPont Dow Elastomers (July 2001) 13. Semiconductor Applications and Compound Selector Guide, Kalrez® Technical Information Bulletin KSE-H88232-00-E0204, DuPont Dow Elastomers (February 2004) 14. Chemraz® 513 Universal Compound for Conventional Applications, Chemraz® Technical Information Bulletin DS-US-SC-007, Greene, Tweed (February 2003) 15. Chemraz® 550 Carbon Loaded, Basic Perfluoroelastomer Seal Material, Chemraz® Technical Information Bulletin DS-US-SC-009, Greene, Tweed (February 2003) 16. Chemraz® 571 Durable Compound for Wet Applications with High Sealing Loads, Chemraz® Technical Information Bulletin DS-US-SC-011, Greene, Tweed (February 2003) 17. Chemraz® 639 Minimal Particulation and Maximum Plasma Resistance, Chemraz® Technical Information Bulletin DS-US-SC-026, Greene, Tweed (October 2003) 18. Chemraz® 655 High Temperature Perfluoroelastomer, Chemraz® Technical Information Bulletin DSUS-SC-024, Greene, Tweed (July 2003)

9 Fluid Resistance of TFE-Olefin Fluoroelastomers 9.1

Introduction

TFE-olefin fluoroelastomers (ASTM designation FEPM) are resistant to strong aqueous base and organic amines that attack VDF-based FKM fluoroelastomers (See Ch. 7). The major FEPM is TFE/ propylene copolymer, a nearly alternating polymer with a slight excess of TFE over propylene units. In the Aflas™ 100 copolymer series made by Asahi Glass, heat treatment is used to generate enough unsaturation to allow peroxide curing. The resulting TFE/P vulcanizates have excellent base resistance and exhibit relatively low swell in polar solvents. However, swell in hydrocarbons, especially aromatics, is high because of the low fluorine content (about 56%). Also, low-temperature flexibility is poor, with vulcanizate TR-10 about 0°C, and the peroxide cure limits continuous service to a maximum temperature of about 220°C. Various terpolymers of TFE/P/VDF have been developed to allow bisphenol curing, with resultant better processing behavior and improved heat resistance. Depending on VDF level, base resistance is somewhat compromised, while hydrocarbon swell is reduced because of higher fluorine content (57%–59%). More efficient bisphenol curing has been attained in TFE/P elastomers by the incorporation of small amounts of trifluoropropylene (TFP), CH2=CH–CF3. The ratio of TFE to propylene units can also be increased in these terpolymers to get higher fluorine content (58%–59%) and reduced swell in hydrocarbons, while retaining excellent base resistance. A specialty FEPM elastomer, ethylene/TFE/ PMVE terpolymer with halogen cure sites for peroxide curing, also has excellent base resistance, since ethylene units flanked by TFE or PMVE units are resistant to dehydrofluorination. Vulcanizates have better low-temperature flexibility than TFE/P, and with the nonpolar nature and higher fluorine content (67%) of the polymer, show low swell in both polar and nonpolar solvents.

9.2

Fluid Resistance of TFE/ Propylene Elastomers

Table 9.1 is a tabulation of chemical resistance data for TFE-propylene copolymer and TFE/P/VDF terpolymer, taken from a previous volume in the PDL Handbook Series.[1] The data were obtained on vulcanizates of heat-treated TFE/P Aflas copolymer made by Asahi Glass and sold in the U.S. by 3M (Dyneon), designated as 3M Aflas (TFP copolymer), or on vulcanizates of TFE/P/VDF terpolymer (probably Aflas 200 made by Asahi Glass) precompounded with bisphenol and accelerator by 3M (Dyneon), designated as 3M Fluorel II FX 11900 (TFP terpolymer). The choice of fluids in Table 9.1 gives a good picture of the suitability of these polymers for service in a wide range of environments. (See Appendix for a description of the PDL Ratings shown in the table.)

9.2.1

TFE/P Dipolymer

From Table 9.1, peroxide-cured vulcanizates of TFE/P dipolymer have excellent resistance to steam, inorganic base, motor oils, lubricants, and oil field mixtures such as sour gas. The vulcanizates have high swell in hydrocarbons and fuels, especially with aromatics present, and relatively high swell in ketones, esters, ethers, and some chlorinated solvents. A typical formulation for medium hardness is:[2] Aflas TFE/P dipolymer MT Black N990

100 30

Peroxide, Vul-Cup 40KE

4

TAIC

4

Sodium stearate

1

The peroxide often used is 2,2´-bis(t-butylperoxy)diisopropylbenzene. For higher hardness and modulus, black level may be increased (furnace black may be added), and also peroxide and/or trap may be increased. Sodium stearate is often used for better release from mill rolls or molds. Dyneon offers five grades of dipolymers differing in molecular weight.[2] In the formulation above, these give typical physical properties as listed in Table 9.2.

228

Table 9.1 Tetrafluoroethylene Propylene Copolymer and Terpolymer[1]

(Cont’d.)

Table 9.1 (Cont’d.)

229

(Cont’d.)

230

Table 9.1 (Cont’d.)

(Cont’d.)

Table 9.1 (Cont’d.)

231

(Cont’d.)

232

Table 9.1 (Cont’d.)

9 FLUID RESISTANCE OF TFE-OLEFIN FLUOROELASTOMERS

233

Table 9.2 Properties of TFE/P Dipolymer Compounds[2]

Polymer (Aflas FA):

100H

100S

150P

150E

150L

ML, in-lb

30

24

14

7

3

MH, in-lb

68

70

60

46

43

ts2, minutes

1.3

1.4

1.6

1.7

1.9

tc90, minutes

6.7

7.1

7.7

8.3

8.8

ODR, 177°C, 3° arc

Typical Physical Properties (press cure 10 min/177°C, post cure 16 h/200°C) M100, MPa

3.9

4.6

4.7

4.1

5.5

TB, MPa

15.8

16.8

14.1

12.3

11.7

EB, %

325

285

270

285

220

72

72

72

73

73

50

44

44

48

42

Hardness, Shore A O-Ring compression set, % 70 hours at 200°C

Heat aging in air at 260°C for 70 hours results in significant loss of modulus and tensile strength, as expected for peroxide-cured vulcanizates.

9.2.2

TFE/P/VDF Terpolymers

The limited data shown for TFE/P/VDF terpolymer vulcanizates in Table 9.1 indicate them to be resistant to automotive lubricants for 7 days: gear lube (150°C), motor oil (163°C), and transmission fluids (163°C). These exposures are not long enough to establish long-term usefulness. The base polymer for Fluorel II probably contains 30%–35% VDF, enough for significant reduction of resistance to amine components of these automotive fluids. An early version of Fluorel II was described by W. M. Grootaert et al., in an ACS Rubber Division paper[3] and appears to have been described in more detail in a subsequent patent.[4] The base polymer exemplified has approximate composition TFE/P/VDF = 42/28/30 mole % (about 59% fluorine) and is precompounded with a tributyl(2-methoxy)propyl phosphonium – Bisphenol AF curative complex along

with tetramethylene sulfone and dimethyl sulfone as additional accelerators and processing aids. The final compounds for curing also contain the usual ingredients 6 phr calcium hydroxide and 3 phr highactivity magnesium oxide along with filler such as 30 phr MT Black N990. Later, bisphenol-curable TFE/P/VDF terpolymers with lower VDF content (10%–15%) were developed to get better base resistance. These terpolymer products are marketed as Dyneon Base Resistance Elastomers, with lowVDF terpolymers designated as the BRE 7100 series and high-VDF terpolymers designated as the BRE 7200 series. Both are more resistant to basic fluids than VDF/HFP/TFE FKM fluoroelastomers, but less resistant than TFE/P dipolymers. Significant differences show up in extended exposures to such fluids at elevated temperatures, as shown in a recent paper by J. G. Bauerle and P. L. Tang. [5] Vulcanizates of TFE/P dipolymer and TFE/P/VDF terpolymers with varying VDF content were exposed at 150°C to an aggressive test oil, ASTM Reference Oil 105, and changes in elongation at break were reported for exposures as long as 12 weeks, as shown in Table 9.3.

234

FLUOROELASTOMERS HANDBOOK

Table 9.3 TFE/P Dipolymer and TFE/P/VDF Tripolymer Vulcanizates: Percent Change in EB after Oil Aging at 150°C[5]

% VDF in Polymer

Exposure time, hours 500

1000

2000

0

-10

-13

-22

10

-18

-26

-42

16

-40

-47

-65

30

-48

-65

-82

Thus, TFE/P/VDF terpolymers exhibit intermediate resistance to aqueous base and amine-containing fluids, so the severity of the fluid exposure conditions needs to be evaluated carefully before deciding on suitability for the service. As noted in Sec. 5.4, TFE/P/VDF terpolymers treated with strong base undergo dehydrofluorination at VDF sites. Most of the resulting unsaturated sites are not susceptible to nucleophilic attack (e.g., polyamines in hydrocarbon automotive lubricants), so vulcanizates usually do not fail by surface cracking and embrittlement. However, such sites are subject to hydrolysis and chain scission in aqueous base.

9.2.3

TFE/P/TFP Terpolymers

Elastomeric copolymers of TFE and propylene with small amounts of trifluoropropylene (TFP), CH2=CH–CF3, are curable with bisphenol and can be made with relatively high fluorine content.[6] As discussed in Sec. 5.4, W. W. Schmiegel has shown that treatment of these terpolymers with strong base results in dehydrofluorination only at TFP sites.[7] J. G. Bauerle and P. L. Tang[5] show that vulcanizates of TFE/P/TFP terpolymer are less affected by exposure to an aggressive test oil than any of the TFE/P/VDF polymers listed in Table 9.3, including the TFE/P dipolymer. In general, TFE/P/ TFP vulcanizates have fluid resistance similar to that of TFE/P dipolymer, but exhibit lower swell in hydrocarbons because of higher fluorine content. Bisphenol-cured TFE/P/TFP has better heat resistance than peroxide-cured TFE/P dipolymer or TFE/P/VDF terpolymers.

Cure characteristics, physical properties, and resistance to heat and oil are shown in Table 9.4 for compounds with various fillers in Viton® Extreme™ TBR-605CS, a precompound of TFE/P/TFP that contains a proprietary bisphenol-accelerator combination.[8] For this precompound, high activity magnesium oxide is recommended for reasonable cure rates instead of the usual combination of calcium hydroxide and magnesium oxide. Relatively high levels of low-reinforcing fillers such as thermal black (MT, N990) or blanc fixe (barium sulfate) can be used with little reduction in cure rate to get vulcanizates of reasonable modulus and hardness, and with reduced swell in hydrocarbon fluids. Reinforcing furnace blacks (FEF or SRF) can be used at modest levels to get vulcanizates with higher modulus, but with some reduction in cure rate. These fillers would have similar effects in compounds of other TFE/P elastomers. The good heat stability of bisphenol-cured vulcanizates is shown by the minimal change in properties after heat aging in air at 250°C for a week. Vulcanizates of this TFE/P/TFP elastomer also show very good resistance to an aggressive test oil, with little loss of properties after six weeks exposure at 150°C. Changes in elongation were 15% or less for these vulcanizates, comparable to that observed for peroxide-cured TFE/P dipolymer and less than changes noted for TFE/P/VDF terpolymers (See Table 9.3). In addition, the relatively high fluorine content of the TFE/P/TFP terpolymer leads to lower swell in oil and other hydrocarbon fluids. Good sealing performance at high temperature is indicated by low compression set of o-rings.

9 FLUID RESISTANCE OF TFE-OLEFIN FLUOROELASTOMERS

235

Table 9.4 Effect of Fillers on TFE/P/TFP Compounds[8]

Compound Viton® Extreme™ TBR-605CS

100

100

100

100

100

100

MgO (high activity)

8

8

8

8

8

8

MT (N990) Carbon Black

10

30

60

SRF (N774) Carbon Black

25

FEF (N550) Carbon Black

20

Blanc Fixe (BaSO4)

60

MDR 2000 at 177°C, 0.5°C ML, dN·m

1.1

1.4

2.2

1.7

1.9

1.5

MH, dN·m

12.6

18.5

30.1

18.1

17.3

16.4

ts2, minutes

1.6

1.5

1.4

2.1

2.4

1.1

tc50, minutes

2.6

3.1

3.9

4.7

5.5

2.1

tc90, minutes

5.4

6.3

8.6

10.2

12.3

4.7

Physical properties - original, press cure 10 min/177°C, post cure 16 h/200°C M100, MPa

3.1

7.2

12.6

9.5

9.9

4.8

TB, MPa

13.9

15.5

15.9

17.9

20.9

11.0

EB, %

280

240

165

175

210

275

Hardness, Shore A, points

66

77

89

79

77

75

Physical properties - heat aged 168 h/ 250°C in oven M100, MPa

2.8

7.6

14.7

8.9

8.6

5.8

TB, MPa

15.7

17.1

17.3

19.2

19.7

10.7

EB, %

285

205

120

185

180

235

Hardness, Shore A, points

64

75

88

78

75

74

Change in physical properties after heat aging M100 change, %

-10

6

17

-6

-13

21

TB change, %

13

10

9

7

-6

-3

EB change, %

2

-15

-27

6

-14

-15

Hardness change, points

-2

-2

-1

-1

-2

-1 (Cont’d.)

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FLUOROELASTOMERS HANDBOOK

Table 9.4 (Cont’d.)

Physical properties - aged 1008 h/150°C in ASTM 105 Oil (5W/30) M100, MPa

2.9

6.7

11.2

9.2

8.0

4.7

TB, MPa

12.5

13.6

13.6

19.4

20.7

11.1

EB, %

255

205

145

195

230

255

Hardness, Shore A, points

61

74

87

75

75

71

Change in physical properties after oil aging M100 change, %

-6

-7

-11

-3

-19

-2

TB change, %

-10

-12

-14

8

-1

1

EB change, %

-9

-15

-12

11

10

-7

Hardness change, points

-5

-3

-2

-4

-2

-4

Volume swell, %

5.4

4.6

3.7

5.1

5.5

4.4

After 70 h at 150°C

15

14

16

17

17

17

After 70 h at 200°C

27

29

33

31

27

31

Compression set, Method B, o-rings, %

9.2.4

Service Recommendations

TFE/P FEPMs are recommended for service in aqueous base or amine-containing fluids at high temperature, applications where VDF-based FKMs may fail in long-term service. TFE/P elastomers are resistant to automotive lubricants and oil well fluids. Peroxide-cured versions are recommended for service in aqueous base. Generally, these products are not recommended for service in automotive or aircraft fuels or other hydrocarbon fluids containing significant fractions of aromatics. Fluid swell may be relatively high in some solvent mixtures; terpolymers with higher fluorine content may be satisfactory in such environments.

9.3

Fluid Resistance of Ethylene/TFE/PMVE Elastomer

Ethylene/TFE/PMVE elastomer (ETP) is a specialty FEPM product designed to have base resistance comparable to TFE/P copolymer, but better

fluid resistance and low-temperature flexibility.[9] The fluorine content of ETP is comparable to that of Viton GFLT and GF, so ETP exhibits low swell in both polar and nonpolar organic fluids. ETP vulcanizates have higher swell in many fluids than perfluoroelastomers (FFKM), but are often usable and have the advantage of better low-temperature characteristics. Because ETP contains ethylene units, it is not resistant to strong oxidizing agents; FFKM should be used in such service. Composition and compounding of ETP elastomers, together with vulcanizate characteristics and comparison of fluid resistance with other fluoroelastomers, are described in Sec. 5.5. Table 5.11 illustrates the wider range of fluid resistance of ETP compared to TFE/P and high-fluorine VDF-based FKM.[10] The description is for the original versions, Viton® Extreme™ ETP-500 and ETP-900, with a bromine-containing cure-site monomer incorporated to allow peroxide curing. A better-processing version with iodine cure sites, Viton® Extreme ETP600S™, has been introduced recently.[11] Both versions have the same broad range of fluid resistance.

9 FLUID RESISTANCE OF TFE-OLEFIN FLUOROELASTOMERS 9.3.1

Fluid Resistance Data

ETP elastomers are resistant to a wide range of fluids.[10] With its high fluorine content, ETP is resistant to: • Aliphatic and aromatic hydrocarbons • Hydraulic fluids • Motor oils • Fuels and alcohol ETP has good resistance to base-containing fluids and polar fluids: • Strong aqueous base • EP gear lubricants • Ketones • Organic amines • Methyl-t-butyl ether (MTBE)

237 emulsion polymerization process. ETP-500 and ETP900 are cured with peroxide using triallyl isocyanurate (TAIC) or trimethallyl isocyanurate (TMAIC) as radical trap. TMAIC gives somewhat better compression set resistance, but slower cure. A new version, ETP-600S, contains iodine cure sites and is made with a semibatch process designed to give high molecular weight polymer with narrow molecular weight distribution. ETP-600S has better processing characteristics,[11] including better mold flow and extrusion characteristics, better demolding, higher modulus and tensile strength at elevated temperatures, and better compression set resistance. TMAIC is not recommended for curing of ETP-600S. The two versions are compared[11] in the same compound: Polymer 100, MT (N990) Black 30, zinc oxide 3, TAIC 3, and peroxide 3 [45% active 2,5-dimethyl2,5-bis(t-butyl peroxy)hexane on an inert filler]. Results are shown in Table 9.6.

• Complex solvent mixtures ETP is not recommended for use in: • CFC fluids, (e.g., CFC–113, CClF2–CCl2F) Effects of several classes of fluids on ETP and other fluoroelastomers are shown in Table 5.11.

9.3.2

Resistance to Oil Field Environments

ETP was originally designed for good resistance to strong base and to mixtures of fluids encountered in oil and gas wells. Extensive testing has been carried out at high temperature in fluid mixtures simulating conditions in deep oil wells. Typical results are shown in Table 9.5.[12] The last two fluids simulate oil field environments: an aqueous brine containing hydrogen sulfide and a water-soluble amine to behave like a high concentration of corrosion inhibitor; and a wet, sour oil containing an oil-soluble amine. VDF-containing fluoroelastomers are essentially destroyed and retain no usable properties under these conditions. TFE/ P dipolymer vulcanizates are also resistant to these base-containing fluids, but would swell more in oil than ETP.

9.3.3

Cure System Effects

The original ETP polymers with a bromine-containing cure-site monomer are made in a continuous

9.3.4

Service Recommendations

ETP fluoroelastomer is recommended for service in environments where lower-cost conventional VDF-based FKMs or TFE/P FEPMs are not satisfactory. This may include severe service in automotive, aeronautical, chemical processing, or oil field industries. ETP can also give satisfactory service in many environments for which FFKM perfluoroelastomers are used. However, FFKM may be necessary in applications where swell in fluids must be minimized, and in special uses such as semiconductor manufacturing operations which require both high environmental resistance and no significant contamination from elastomer parts.

Table 9.5 ETP-500 Fluoroelastomer: Exposure to Severe Environments (3 days at 150°C)[12]

Fluid

% Volume Swell

30% KOH

12

Sour brine (10% H2S, 5% amine)

17

Wet sour oil (10% H2S, 5% amine)

12

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FLUOROELASTOMERS HANDBOOK

Table 9.6 Comparison of ETP Elastomers[11]

Viton Extreme

ETP-900

ETP-600S

ML, dN·m

2.5

1.7

MH, dN·m

14.4

25.4

ts2, minutes

0.5

0.4

tc50, minutes

0.9

0.7

tc90, minutes

3.3

1.6

MDR, 177°C, 0.5° arc

Physical properties - original, cured 7 min/177°C, post cure 16 h/232°C M100, MPa

8.9

9.1

TB, MPa

18.3

19.0

EB, %

201

191

Hardness, Shore A

76

80

Compression set, Method B, O-Rings, % After 70 hours at 200°C

49

43

TR-10, °C

-6

-7

Gehman, T10, °C

-11

-11

TB, % change

-9

-14

EB, % change

12

38

Methyl ethyl ketone (MEK), 23°C

21

18

Toluene, 40ºC

9

9

50/50 MEK/Toluene blend, 40°C

17

16

Methyl t-butyl ether (MTBE)

30

28

Water, 100°C

8

5

30% Potassium hydroxide, 100°C

1

4

ASTM service fluid 105, 150°C

2

2

Wheel bearing lubricant, 150°C

3

3

Shell EP gear lube, 150°C

4

3

Low temperature properties

Physical properties - after heat aging 168 h at 250°C

Volume change, % - after aging 168 h in various fluids

9 FLUID RESISTANCE OF TFE-OLEFIN FLUOROELASTOMERS

239

REFERENCES 1.

Chemical Resistance Volume 2: Elastomers, Thermosets and Rubbers, PDL Handbook Series, Chemical Resistance – Tetrafluoroethylene Propylene Copolymer and Terpolymer, Second Edition, pp. 280-284, William Andrew Inc., Norwich, NY (1994)

2.

Chemical Resistance - Aflas™ TFE Elastomers, Dyneon Technical Information bulletin 98-0504-11515 (January 2001)

3.

W. M. Grootaert, R. E. Kolb, and A. T. Worm, “A Novel Fluorocarbon Elastomer for High-Temperature Sealing Applications in Aggressive Motor Oil Environments,” paper presented at ACS Rubber Division meeting, Detroit, Michigan (October 17-20, 1989)

4.

W. M. A. Grootaert and R. E. Kolb, U.S. Patent 4,912,171, assigned to Minnesota Mining and Manufacturing Company (March 27, 1990)

5.

J. G. Bauerle and P. L. Tang, “A New Development in Base-Resistant Fluoroelastomers,” Paper Number 02M-137, SAE World Congress, Detroit, Michigan (March 2002)

6.

J. G. Bauerle and W. W. Schmiegel, U.S. Patent Application Publication No. U.S. 2003/0065132 (April 3, 2003)

7.

W. W. Schmiegel, “A Review of Recent Progress in the Design and Reactions of Base-Resistant Fluoroelastomers,” paper presented at International Rubber Conference, Nurenberg, Germany (June 30 – July 3, 2003)

8.

Viton® Extreme™ TBR-605CS: A New, Bisphenol-Cure, Base-Resistant Polymer, DuPont Dow Elastomers Technical Information Bulletin VTE-A10197-00-A1003 (October 2003)

9.

A. L. Moore, U.S. Patent 4,694,045, assigned to DuPont Company (September 15, 1987)

10.

R. D. Stevens and A. L. Moore, “A New, Unique Viton® Fluoroelastomer With Expanded Fluids Resistance,” paper presented at ACS Rubber Division Meeting, Cleveland, Ohio (October 21-27, 1997)

11.

T. M. Dobel and R. D. Stevens, “A New Broadly Fluid Resistant Fluoroelastomer Based on APA Technology, Viton® Extreme™ ETP-S,” paper presented at ACS Rubber Division Meeting, Cleveland, Ohio (October 14-17, 2003)

12.

A. L. Moore, “Base-Resistant Fluoroelastomers Developed For Severe Environments,” Elastomerics, pp. 14-17 (September, 1986)

10 Fluoroelastomer Applications 10.1 Introduction Fluoroelastomers are used mainly in seals and other fabricated parts to provide barriers against a wide range of fluids under severe service conditions, as described briefly in Ch. 1 and in more detail in Chs. 7 to 9. About two-thirds of fluoroelastomers produced are used in automotive applications, mainly in fuel and power train systems, covered in more detail in Chs.12 and 13. Amounts of fluoroelastomers used per vehicle are small, less than 500 g and averaging only 100–200 g, but the parts are crucial for safe, reliable operation and environmental protection. Other fluoroelastomers applications are in a number of areas: aerospace, appliances, fluid power, the chemical industry, the oil field, semiconductor fabrication, and a variety of industrial uses. Some of these are covered in previous chapters describing the characteristics of various fluoroelastomer families. An example of industrial use is covered in Ch. 14 on compounds for power plant service. Other specialized applications, including fluoroelastomers use as process aids in extrusion of hydrocarbon thermoplastics, are described in Ch. 15.

10.2 Major End Uses About a third of fluoroelastomer production goes into o-ring seals used in many industries. Gaskets and molded parts consume a similar volume of fluoroelastomers. Compounding for o-rings and molded goods is covered in Ch. 11. Automotive shaft seals and valve stem seals are major applications; compounding for these is described in Ch. 13. Other end uses, such as hose, flue duct expansion joints, and process aids, are much lower in volume. In many applications, fluoroelastomers are replacing other elastomers, as performance requirements become more stringent. Fluoroelastomers give improved long-term, maintenance-free service in severe environments and more reliable protection of

the environment. The demand for better performance has also forced fluoroelastomer suppliers to develop more resistant high-fluorine polymers and improved curing systems for many applications.

10.3 Fabrication Methods Processing of fluoroelastomers is described in Ch. 6. By far the most common method of fabricating fluoroelastomer parts is molding. Compression molding is widely used, especially for making highperformance seals from fluoroelastomers with relatively high molecular weight. Transfer and injection molding are increasing in importance, to allow lowcost, high-volume production of precision parts. Since individual fabricators favor (or have on hand) different kinds of molding equipment, fluoroelastomer suppliers often must develop several polymers and compounds for satisfactory processing behavior in different molding methods for making parts for the same application. In all molding operations, short molding cycles with good release of parts from the mold are desired. However, some parts, such as shaft seals, require good bonding to a metal or thermoplastic substrate, necessitating special compounding with good bonding agents. Extrusion is widely used to make preforms for compression molding. Compounds must be designed to make extruded cross sections with reproducible dimensions over a range of extruder conditions. Extruders are also major components of transfer and injection molding equipment. Here, a major consideration is the delivery of reproducible shots of compound to the mold. For other applications, precision extruded shapes (tubing, rod, cord, and veneer) are formed for curing without additional shaping. Certain applications, such as flue duct expansion joints (Ch. 14), require calendered sheet. Other processing methods used for special applications are described in Ch. 15.

11 Compounds for O-Rings and Molded Goods 11.1 O-Rings A large fraction of fluoroelastomer production goes into o-rings used as static seals in many industries, including automotive, aeronautical and aerospace, chemical processing and transportation, oil and gas production, food and pharmaceutical, and semiconductor fabrication industries. Bisphenolcured VDF/HFP dipolymer compounds satisfy the bulk of o-ring applications. These compounds exhibit good sealing characteristics over a wide range of temperatures, from about -20°C to 250°C, and are resistant to many fluids. Compounds based on VDF/HFP/TFE fluoroelastomers with high fluorine content are used for o-ring seals against polar fluids that would cause excessive swell in dipolymer compounds. Peroxide-curable fluoroelastomers are used for service in hot aqueous environments, and VDF/ PMVE/TFE polymers provide better seal performance at low temperatures as well as excellent fluid resistance at high temperatures. For very aggressive environments, o-rings based on specialty polymers (TFE/PMVE fluoroelastomers, TFE/P and E/TFE/ PMVE FEPMs) are used. These are described in Ch. 2 (Secs. 2.4, 2.5, and 2.6), Ch. 5 (cure systems, Secs. 5.4, 5.5, and 5.6), and Chs. 8 and 9 (fluid and heat resistance), and will not be discussed here. O-rings are relatively simple shapes made by compression, transfer, or injection molding. O-ring compounds must have adequate flow characteristics for rapid filling of mold cavities, must cure rapidly to high states of cure, and the cured rings must be removed from the mold cleanly and easily. Close control of o-ring dimensions is necessary for a wide range of sizes. Many proprietary bisphenol precompounds have been developed to get optimum processing behavior and final vulcanizate properties for o-rings made by different molding processes for various end uses.

11.1.1

Specifications

The most stringent specifications for o-rings are American military and aeronautical specifications AMS-R-83248B, AMS 7276D, and AMS 7259A. All fluoroelastomer producers offer VDF/HFP

polymers compounded with bisphenol to meet these specifications. Most of the products offered are proprietary precompounds containing curative, accelerator, and optional process aids. Major requirements are listed in Table 11.1, along with a comparison with properties of a typical compound designed to meet these o-ring specifications.[1] The specifications emphasize original properties, heat stability, compression set, and resistance to hydrocarbon fuel and ester lubricant. Low-temperature flexibility (TR10) specifications can be met by VDF/HFP dipolymers with composition 60% VDF (66% fluorine), but not by VDF/HFP/TFE terpolymers with higher fluorine content. Bisphenol-cured compounds can pass 275°C heat-aging specifications; peroxide cures are not usually stable enough for this test.

11.1.2

Compression Set Measurement

Compression set tests are ordinarily used as a measure of sealing performance of o-ring compounds. ASTM tests such as D1414 for o-rings generally give reliable comparisons of compounds, but do not simulate conditions in actual applications. In this test, o-rings of standard size (25 × 3.5 mm, 1.0 × 0.139 in) are installed between flat plates stacked in a jig, not in grooves as in actual service. The o-rings are compressed by 25% using spacers between plates to give uniform strain. The assembly is then subjected to the prescribed temperature in an air oven for a specified time. After exposure, the jig is removed from the oven and the o-rings are removed and allowed to recover at room temperature for a set time (30 minutes) before measuring final thickness and degree of set (as percent unrecovered strain). O-ring specifications usually require compression set less than 20% for tests at 200°C in air for up to 70 hours. Most fluoroelastomer cure systems give cross links that are stable under these exposure conditions, so these short-term tests do not usually involve significant primary network breakdown. This protocol is convenient, but does not simulate performance of seals subjected to temperature cycling while maintained under strain. Variants of the ASTM D1414 method have been proposed and

244

FLUOROELASTOMERS HANDBOOK

Table 11.1 Specifications for Fluoroelastomer O-Ring Compound[1]

Vulcanizate Properties

Viton A-401C

Specification Limits AMS-R-83248B AMS 7276D

Stress/strain, 23°C – Original, post cured Tensile strength, MPa 13.7 9.65 min. 9.65 min. Elongation at break, % 191 125 min. 125 min. Hardness, Shore A 76 75±5 75±5 TR-10, °C -15 -15 max. -15 max Stress/strain, 23°C – After aging 70 h at 275°C Tensile strength, % change -23 -35 max. -35 max. Elongation at break, % change +21 -15 max. -15 max. Hardness, pts change 0 -5 to +10 0 to +10 Weight loss, % 4 10 max. 10 max. Stress/strain, 23°C – After aging 70 h at 23°C in TT-S-735 type III (ASTM Reference Fuel B) Tensile strength, % change -8 -20 max. -15 max. Elongation at break, % change -3 -20 max. -15 max. Hardness, pts change -1 -5 to +5 -5 to +5 Volume swell, % +1 +1 to +10 0 to +5 Stress/strain, 23°C – After aging 70 h at 175°C inAMS 3021 (Stauffer 7700 Blend) Tensile strength, % change -15 -30 max. -30 max. Elongation at break, % change -7 -20 max. -20 max. Hardness, pts change -10 0 to -15 -15 to +5 Volume swell, % +15 +1 to +20 0 to +20 Compression Set, Method B, 25 x 3.5 mm O-rings, % 70 h at 23°C 166 h at 175°C 22 h at 200°C 70 h at 200°C 336 h at 200°C

6 16 9 16 30

15 max. 20 max. 20 max. ---

---20 max. 40 max.

Viton A-401C Compound Viton A-401C MT Black (N990) Magnesium Oxide, Maglite D Calcium Hydroxide

100 30 3 6 Press cure 10 min at 177°C Post cure 24 h at 232°C

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS used to simulate service conditions better. One European auto company prescribes cooling in clamps under strain, then removal of o-rings for thickness measurement. The higher compression set observed in such tests is a measure of formation of secondary networks at high temperature under strain (e.g., polymer chain end group association, interactions of polymer with filler and metal oxide particles) or of lockedin chain conformations under strain caused by crystallinity or closer proximity to the glass transition range. Recovery from strain is much slower at room temperature than at higher temperatures. O-ring compression set testing in fluids would be much more complicated, and is rarely attempted. Minimal swell by fluids (say, less than 10%) may actually improve o-ring sealing performance under conditions where temperatures are cycled between high and low extremes. However, high swell (above 20%) could result in loss of sealing force or extrusion of the highly swollen ring from the groove. More realistic assessment of sealing performance in fluids can be obtained from compression stress relaxation measurements.[2] In this test, die-cut gaskets (2-mm thickness) are installed in Shawbury-Wallace or Jamak jigs and immersed in fluid. After the prescribed exposure, jigs are removed from the fluid and a Shawbury-Wallace load cell is used to measure retained sealing force. Typical results show an initial decrease in sealing force caused by fluid sorption, followed by trends that reflect effects of the fluid exposure on the elastomer network. Such stress relaxation results are often quite different from oring compression set results, especially for high-fluorine elastomers, which show slow recovery from strain in the o-ring tests.

11.1.3

VDF/HFP Dipolymer Compounds

All fluoroelastomer producers offer VDF/HFP dipolymer precompounds with incorporated bisphenol crosslinker, accelerator, and optional processing aids for compounds used to make high quality orings in various molding processes. A partial listing of recent recommendations is compiled in Table 11.2. Most of these precompounds are designed for full (black) compounds with composition: 100

245 precompound, 30 MT Black (N990), 6 calcium hydroxide, 3 magnesium oxide (high activity). Tecnoflon® FOR 80HS and 50HS are designed for curing with no calcium hydroxide (8 phr MgO only) and only a short post cure. All the dipolymers contain about 60% VDF, and are made under conditions which produce relatively narrow molecular weight distribution and very low levels of ionic end groups. Residual salts, soaps, and low molecular weight oligomers are kept to very low levels in the dipolymers. Precompounds are formulated with relatively high concentrations (about 2 phr) of Bisphenol AF to get high crosslink density and low levels of quaternary ammonium or phosphonium accelerators for low compression set. Processing aids are incorporated in some precompounds for improved extrusion and demolding characteristics. However, levels of fugitive additives are kept low to avoid excessive shrinkage after oven post curing. The classification of precompounds into medium to high viscosity types for compression molding and low to medium viscosity types for transfer and injection molding is somewhat arbitrary. Medium viscosity compounds can be injection molded successfully with modern equipment. Some of the precompounds are set up to allow very fast curing cycles in high-temperature injection molding. More detailed information on precompounds offered for fabrication of highquality o-ring seals is available from the suppliers. The web sites listed in the references for Table 11.2 contain suggestions for precompounds best suited to various fabrication techniques. It should be noted that the table does not include a number of older products developed in the 1970s and early 1980s for o-rings and other molded parts. These include Viton® E-60C and E-430 from DuPont Dow, and Dyneon® FC 2174, 2179, 2180, 2121, and 2110Q, which are still used by many fabricators. Fillers affect compound stock viscosity and vulcanizate properties significantly. For black compounds, thermal black with large particle size, MT Black (N990), is commonly used in fluoroelastomers. The effect of varying black level on properties of Viton® A-401C compounds is shown in Table 11.3; the compounds contain 3 phr MgO (Maglite D), and 6 phr Ca(OH)2, in addition to black.[1]

246

FLUOROELASTOMERS HANDBOOK

Increased carbon black levels give higher viscosity stocks, which cure to vulcanizates with higher hardness, modulus, and tensile strength, but lower elongation at break. Compression set increases with increasing black level. Vulcanizates with higher black level swell less in fluids, resulting in less deterioration in mechanical properties. Furnace blacks such as SRF (N774) or FEF (N550) may be used, but levels must be kept low to keep reasonable vulcanizate modulus, hardness, and EB. For many o-ring seal applications, it is necessary for fluoroelastomer seals to be readily identifiable to distinguish them from similar seals made of

different materials. This is especially necessary to avoid mistakes in installing seals in automobiles and chemical industry equipment. Because of this, end users often specify fluoroelastomer o-rings to have particular colors. Mineral fillers must be used to avoid masking pigment colors. A number of mineral fillers can be used in fluoroelastomers without significant loss of properties compared to black fillers. Levels must be adjusted to get desired hardness. Table 11.4 lists effects of several acceptable mineral fillers on properties of Viton® A-401C compounds, all of which contain 30 phr filler with 6 phr Ca(OH)2 and 3 phr MgO.

Table 11.2 VDF/HFP Dipolymer Precompounds Recommended for High-Quality O-Ring Seals

Precompounds Supplier

Trade Name Compression Molding

Injection Molding

A-401C, A-402C DuPont Dow

Viton[3]

A-601C

A-201C, A-202C

A-331C

A-275C

A-361C FE 5640Q Dyneon

Dyneon[4]

FE 5641Q FE 5660Q

FE 5610 FE 5620Q FE 5621 FE 5623

G-701 Daikin

Dai-el[5]

G-716 G-751

G-704

G-783 FOR 421/U Solvay-Solexis

Tecnoflon[6]

FOR 532

FOR 423/U

FOR 80HS

FOR 432 FOR 50HS

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

247

Table 11.3 Effect of Carbon Black Level in Viton A-401C[1]

MT Black, phr 60

45

30

15

5

2

Stock Properties Viscosity ML-10 (121°C)

115

98

80

67

62

57

ODR at 177°C, Microdie, 3° Arc ML, in-lb

23

21

15

17

15

14

MH, in-lb

164

151

122

118

102

92

ts2, minutes

1.3

1.5

1.7

1.9

2.1

2.8

tc90, minutes

2.6

2.8

3.2

3.4

3.6

4.6

Vulcanizate Properties (press cured 10 min at 177°C, post cured 24 h at 232°C) Stress/strain at 23°C – Original M100, MPa

11.9

9.4

6.4

3.7

2.1

1.4

TB, MPa

14.5

13.9

13.4

11.4

9.7

6.5

EB, %

130

156

199

216

240

239

Hardness, Shore A

90

84

75

63

57

53

Stress/strain at 23°C – Aged 70 h at 232°C M100, MPa

13.4

10.9

7.2

3.8

2.0

1.5

TB, MPa

13.8

13.7

14.0

12.7

9.3

7.3

EB, %

104

127

177

220

241

249

Hardness, Shore A

92

86

80

69

62

57

Compression Set, Method B, O-rings, % 70 h at 200°C

21

18

15

13

9

12

336 h at 200°C

38

33

29

25

25

24

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FLUOROELASTOMERS HANDBOOK

Table 11.4 Effect of Mineral Fillers on Viton® A-401C[1]

Filler Nyad ® 400

Celite ® 350

Blanc Fixe

TI-PURE® R-960

87

80

107

75

78

MT Black Albagloss Stock Properties Viscosity ML-10 (121°C)

80

ODR at 177°C, Microdie, 3° Arc ML, in-lb

15

22

20

24

19

19

MH, in-lb

122

124

122

132

113

106

ts2, minutes

1.7

1.7

1.9

1.7

2.0

1.9

tc90, minutes

3.2

3.6

3.0

2.9

3.5

4.1

Vulcanizate Properties (press cured 10 min at 177°C, post cured 24 h at 232°C) Stress/strain at 23°C – Original M100, MPa

6.4

6.5

8.4

14.4

3.4

4.1

TB, MPa

13.4

12.8

11.4

15.8

9.9

11.0

EB, %

199

153

154

110

211

176

Hardness, Shore A

75

67

67

79

63

66

Stress/strain at 23°C – Aged 70 h at 232°C M100, MPa

7.2

6.3

7.5

12.7

3.2

3.8

TB, MPa

14.0

13.2

10.8

15.1

9.7

12.8

EB, %

177

179

189

125

245

220

Hardness, Shore A

80

70

69

79

64

67

Compression set, Method B, O-rings, % 70 h at 200°C

15

18

13

18

12

12

336 h at 200°C

29

41

29

32

29

26

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

249

Compositions of the mineral fillers listed in Table 11.4 are: Albagloss (precipitated calcium carbonate), Nyad® 400 (calcium metasilicate), Celite® 350 (diatomaceous silica), Blanc Fixe (precipitated barium sulfate), and TI-PURE® R-960 (rutile titanium oxide). With some adjustment in levels of some of the fillers to get vulcanizate hardness close to that imparted by 30 phr MT Black, most of the other properties would also come into desired ranges for medium hardness parts. In a Dyneon study,[7] mineral filler levels were adjusted to get hardness near 75 durometer in Dyneon® FC 2170 compounds. As in the DuPont Dow study, Nyad® 400 and barium sulfate gave satisfactory results. Calcium carbonate gave marginally high weight loss after heat aging at 276°C. Clay, mica, and asbestos fillers gave high compression set or high weight loss

on heat aging and thus would not be generally satisfactory for use in fluoroelastomers. Cure rate and state of compounds derived from VDF/HFP dipolymer precompounds are mainly set by the levels of incorporated bisphenol and accelerator. Some adjustment in cure rate is possible by varying the ratio of Ca(OH)2 to MgO (Elastomag® 170) in the compound, as shown in Table 11.5 for a medium viscosity Dyneon® FE 5640Q precompound formulated with 30 phr MT Black.[7] Compared to the “standard” Ca(OH)2/MgO ratio of 6/3 phr in compound D, other ratios give small changes in cure rate and little change in vulcanizate properties, except for higher compression set at the highest levels of both components. For molded composite parts, which require good adhesion to metal inserts, high MgO levels are often recommended.

Table 11.5 Effect of Ca(OH)2/MgO Ratio on Dyneon® FE 5640Q[7]

Compound A

B

C

D

E

Ca(OH)2

3

3

3

6

6

MgO

3

6

9

3

9

Minimum viscosity

39

44

44

42

51

Pts rise in 30 min

<3

<3

<3

<3

<3

ML, in-lb

1.5

1.8

1.8

1.7

2.3

MH, in-lb

25.5

22.8

25.4

26.0

19.2

ts2, minutes

3.1

2.6

2.0

2.4

1.7

tc90, minutes

6.6

6.2

3.9

5.1

4.2

Composition

Stock Properties Mooney Scorch, 121°C

MDR at 177°C

Vulcanizate Properties (press cured 10 min at 177°C, post cured 16 h at 232°C) Stress/Strain at 23°C – Original M100, MPa

4.9

5.2

6.0

5.7

5.1

TB, MPa

14.0

14.3

14.6

14.3

15.0

EB, %

220

210

200

210

215

Hardness, Shore A

74

74

75

75

76

12

12

11

18

Compression set, Method B, O-rings, % 70 h at 200°C

10

250 Most fluoroelastomer suppliers emphasize precompounds with curatives incorporated at proprietary levels for various end uses and processing methods. Little information is widely available for the effects of curative levels on cure behavior and final properties of compounds based on fluoroelastomers developed in the last ten or fifteen years. However, some studies have been published on the effects of varying levels of Bisphenol AF (BpAF) crosslinker and benzyltriphenylphosphonium chloride (BTPPC) on older VDF/HFP dipolymers. These curatives are supplied by some producers as concentrated masterbatches in dipolymer. In a DuPont study, A. L. Moran[8] provides information on the effects on Viton® E-60 of varying levels of Curative 30 (50% BpAF) and Curative® 20 (33% BTPPC), as shown in Figs. 11.1 to 11.4. Curative 30 was varied from 2 phr to 6 phr (1 phr to 3 phr BpAF) and Curative 20 from 0.75 phr to 3 phr (0.25 phr to 1 phr BTPPC), approximately the ranges of interest for practical compounds. From Fig. 11.1, cure rates are mainly dependent on Curative 20 accelerator level, as indicated by ODR tc90 cure times. Very slow cures are obtained at the lowest accelerator level, corresponding to 0.25 phr BTPPC (6.5 mmoles/kg polymer), not much above the concentration of ionic end groups in E-60. Ionic end groups may associate strongly enough with quaternary phosphonium ions to keep a significant fraction of the BTPPC from being effective in accelerating the cure. This effect is minimized in more recently developed polymers, such as Viton A-500, with much lower ionic end groups, so that fast cures can be obtained with lower accelerator levels. Bisphenol AF has less effect on cure rate, except for retardation at very high ratios of BpAF to BTPPC. From Figs.11.2 to 11.4, vulcanizate properties that reflect state of cure are mainly dependent on Curative 30 (BpAF) crosslinker level. Thus, higher BpAF levels lead to higher modulus (also higher hardness) and lower elongation at break, as well as lower compression set. In bisphenol-cured compounds, very low compression sets require very high crosslink density, with elongation at break 200% or less at room temperature. For seals under compression at high temperatures, EB decreases significantly, so care must be taken in part design to avoid local failures where elongation exceeds EB. Modern polymers would give lower compression set than E-60, but other effects of BpAF level on mechanical

FLUOROELASTOMERS HANDBOOK properties would be similar to those shown in Figs. 11.2 to 11.4. For curing of modern dipolymers such as Viton A-500 and A-700, DuPont Dow offers Viton® Curative No. 50 (VC-50), a combination of Bisphenol AF with a quaternary phosphonium accelerator in a ratio of about four to one. The effects of varying VC-50 levels on A-700 curing are reported in Table 11.6[9] for a general recipe similar to that used for the E-60 curative study described in Figs. 11.1 to 11.4. With the constant accelerator to crosslinker ratio in VC-50, cure rate of A-700 as measured by ODR tc90 does not change much with VC-50 level, and is much faster than that of E-60 stocks. The main effect of changing VC-50 level is on vulcanizate properties related to state of cure. Thus, vulcanizate modulus increases, while elongation at break and compression set decrease with increasing VC-50 level. At the usual level of VC-50 of 2.5 phr recommended for o-rings, compression set is lower for A700 than for E-60 at equivalent BpAF level. VDF/HFP dipolymer gums are available from most suppliers in a range of viscosities, as listed in Table 11.7. All of these polymers contain about 60% VDF (65% fluorine), and are designed for use with bisphenol curatives. These dipolymer gums may be formulated with available curative masterbatches: Viton® Curative 30 or Tecnoflon Curative M1, both containing 50% Bisphenol AF in fluoroelastomer; and Viton Curative 20 (33% BTPPPC) or Tecnoflon Curative M2 (30% accelerator). The combined curative mixture of BpAF and accelerator, Viton Curative 50, can also be used (see Table 11.6). Low-viscosity gums may be added to compounds to obtain better flow characteristics, and high-viscosity gums may be added to obtain better green strength or modulus of compounds. Any of the gums may be mixed with precompounds to get reduced cure state and higher elongation at break. VDF/HFP dipolymer precompounds recommended for molded goods are listed in Table 11.8. Several of these are also recommended for highquality o-rings (see Table 11.2). A number of precompounds are designed with special attributes, described in footnotes to the table. Such precompounds may contain process aids for better flow, release aids, or adhesion promoters for bonded parts. Bisphenol and/or accelerator levels may be varied to get high elongation or faster cure.

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

251

Figure 11.1 ODR at 350°F (177°C) tC90, minutes.[8]

Figure 11.2 100% Modulus, psi (MPa).[8]

Figure 11.3 Elongation at break, %.[8]

Figure 11.4 Compresson set – Method B, % (o-rings), 70 hours at 392°F (200°C).[8]

252

FLUOROELASTOMERS HANDBOOK

Table 11.6 Effect of Varying VC-50 Curative on Viton® A-700[9]

Curative VC-50, phr 3.0

2.5

2.0

1.5

3.8

3.3

3.4

3.4

ODR at 177°C tc90, minutes

Vulcanizate Properties – Original (press cure 10 min at 177°C, post cure 24 h at 232°C) Stress/strain at 23°C M100, MPa

7.9

6.9

5.5

4.3

EB, %

160

200

235

290

11

14

16

20

Compression Set, O-rings, %70 h at 200°C

Table 11.7 VDF/HFP Dipolymer Gums (65% F)

Trade Name

Viscosity ML-10 (121°C)

[3]

Viton

Dyneon[4]

Tecnoflon[10]

10–15

A-100

FC 2211

N 215

20–30

A-200, E-45

FC 2145

N 535

40–60

A-500, E-60

FC 2230

N 935

70–90

A-700

FC 2178

100+

A-HV

Table 11.8 VDF/HFP Dipolymer Precompounds Recommended for Molded Parts

Supplier

Trade Name

Precompounds Compression Molding a

DuPont Dow

[3]

Viton

Dyneon

Dyneon[4]

Daikin

Dai-el[5]

Solvay-Solexis

Tecnoflon[11]

InjectionMolding

A-331C A-361Cc A-402Cd

A-201C A-202Cb A-275Cb

FC 2144 FC 2152 FC 2153Xb FC 2177Dc FC 2181c

FC 2122b FC 2123b

G-701 G-751c G-783b

G-704d

FOR 531a FOR 60Kb

FOR 5351/Ua

Notes: aHigh elongation. bExcellent mold release for complex shapes. c Good adhesion for bonded parts. dFast cure.

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

253

11.2 VDF/HFP/TFE Compounds

VDF content to get similar vulcanizate properties. Cure rates are about the same as for dipolymers when the same accelerator levels are used. The terpolymers have slightly better low-temperature characteristics, with TR-10 lower by 2°C–3°C. The curative levels for the Viton and Tecnoflon gum terpolymers in Table 11.11 correspond to 2 phr Bisphenol AF and about 0.5 phr phosphonium accelerator. Similar cure rates and states would be obtained with the Dyneon terpolymer gums or precompounds and the Dai-el® precompound with 66% fluorine content. Heat aging and fluid resistance are all about the same, and similar to dipolymer results. VDF/HFP/TFE terpolymers with somewhat higher fluorine content (about 68%, corresponding to about 50% VDF) also can be cured satisfactorily in recipes similar to those used for dipolymers. With the same levels of bisphenol and accelerators, cure rates and states are about the same as for the 66% fluorine terpolymers and dipolymers. Compression set and heat aging characteristics are similar to those of dipolymer vulcanizates. Low-temperature characteristics resemble those of dipolymer, with TR-10 values of -18°C to -19°C for medium hardness vulcanizates. Fluid swell is somewhat lower because of the lower VDF content (higher percent fluorine). Curing of typical bisphenol precompounds of medium-viscosity VDF/HFP/TFE terpolymers containing 69% fluorine is illustrated in Table 11.12. States of cure are somewhat different for these precompounds. Some are set up for low compression set with low elongation at break, while others are formulated to get higher elongation with higher set. Low-temperature characteristics are somewhat worse (TR-10 values are 4°C–8°C higher) than those of polymers with lower fluorine content. However, these terpolymer vulcanizates are more fluid resistant, especially to polar solvents. Curing characteristics and vulcanizate properties are shown in Table 11.13 for medium viscosity bisphenol precompounds of VDF/HFP/TFE terpolymers with very high fluorine content (70%–71%, corresponding to 30%–36% VDF). These precompounds contain Bisphenol AF and proprietary accelerator systems designed to get reproducible, fast cures. As noted previously, fluoroelastomer suppliers do not usually sell high-fluorine gum terpolymers, since bisphenol curing is difficult to carry

Fluoroelastomer producers offer a wide range of VDF/HFP/TFE gum polymers and precompounds, with fluorine content 66% to 71% (60% to 30% VDF). Terpolymers may be cured with bisphenol, but polymers with higher fluorine content require higher levels of accelerator or more active accelerators than used for dipolymers containing 66% fluorine. VDF/HFP/TFE elastomers with bromine or iodine cure sites may be cured with peroxide systems to get vulcanizates more resistant to hot aqueous fluids, but with somewhat lower heat stability than bisphenol vulcanizates. Gum terpolymers offered by various suppliers are listed in Table 11.9. These can be compounded with available curatives (e.g., Viton Curatives 20, 30, and 50, or Tecnoflon Curatives M1 and M2), with Bisphenol AF levels similar to those recommended for dipolymers. Higher accelerator levels (VC-20 or M2) may be necessary for high-fluorine types. Bisphenol-containing VDF/HFP/TFE terpolymer precompounds are listed in Table 11.10. These are designed with proprietary accelerators to get fast cures with reasonable scorch safety, and several contain processing aids to facilitate extrusion, mold flow, and/or mold release. Compounds of terpolymers containing 66% to 68% fluorine have good lowtemperature characteristics, equal to, or better than, those of dipolymers with 66% fluorine content. Compounds of terpolymers with higher fluorine content, 69% to 71%, have better fluid resistance, important for molded seals and other parts in automotive systems or chemical process industry service. Especially for terpolymers with very high fluorine content, precompounds from suppliers generally give more reliable cures than many fabricators can attain by compounding gums with available curatives. Several of the products listed are developmental, and may be modified somewhat based on polymer and parts production experience. These include Dyneon products designated with an X or Q suffix and DuPont Dow VTR products. All cure data presented here are from laboratory-scale work-up. Fullscale production results may differ. As shown in Table 11.11, terpolymers containing 66% fluorine (60% VDF) can be cured in recipes similar to those used for dipolymers of the same

254 out with available curatives. Precompounds such as those listed in Tables 11.10 and 11.13 give more reliable performance. Vulcanizates of these highfluorine precompounds have poorer low-temperature characteristics, but greater resistance to polar fluids than those of precompounds with lower fluorine content. Peroxide-curable VDF/HFP/TFE fluoroelastomers have been developed by all suppliers to get vulcanizates with improved resistance to steam and aqueous fluids than those from bisphenol-curable terpolymers. Thermal stability is somewhat lower for peroxide-cured vulcanizates, but all are capable of long-term service at temperatures of at least 200°C. Peroxide curing of high-fluorine polymers is somewhat easier to carry out reproducibly than bisphenol curing. Since dehydrofluorination of sites on polymer chains is not involved in peroxide curing, compounds contain little or no inorganic base. Usually zinc oxide is used at low levels, rather than the relatively high amounts of calcium hydroxide and magnesium oxide required for bisphenol curing. Available peroxide-curable VDF/HFP/TFE fluoroelastomers are listed in Table 11.14. Peroxide curing, as described in Sec. 5.2.3, is based on free radical reaction with bromine or iodine sites on polymer chains, followed by crosslink formation by interaction of a multifunctional polymerizable trap with the resulting chain radical sites. The first polymers developed, exemplified by Viton GF and GBL-900 and Dyneon FLS 2650, have bromine cure sites along the chains from incorporation of cure-site monomers. These tend to give relatively slow cures with triallylisocyanurate (TAIC) or trimethallylisocyanurate (TMAIC), and have poor demolding characteristics. The polymers have significant branching, with resultant mediocre flow characteristics. Thermal stability is fairly good, with long term service possible up to about 230°C. Daikin developed narrow molecular weight distribution polymers with iodine end groups on most chain ends. These poly-

FLUOROELASTOMERS HANDBOOK mers, typified by Dai-el G-901 and G-902, cure rapidly with TAIC and have excellent demolding characteristics. Vulcanizates have excellent compression set resistance, but upper service temperature is about 200°C. Later, DuPont developed polymers with iodine end groups and incorporated bromine-containing cure-site monomer, to get good curing characteristics and better thermal stability (Viton GBL-200 and GF300). More recent products contain iodine end groups and incorporated iodine-containing cure-site monomer to get very fast cures, excellent processing characteristics, and good thermal stability. These modern products include Viton GBL-S and GF-S; Dai-el G-912 and G-952; and Tecnoflon P 457, P 757, P 459, and P 959. Compounds based on polymers containing iodine cure sites require short or no oven post curing to develop good properties. The progression of peroxide cure characteristics and vulcanizate properties is shown[24] in Table 11.15 for the high-fluorine Viton polymers: GF, a relatively high-viscosity polymer with incorporated bromine-containing cure-site monomer giving broad molecular weight distribution; GF-300, a low-viscosity polymer with bromine cure sites along chains and mostly iodine end groups for narrow molecular weight distribution; and medium-viscosity GF-S, with iodine along chains and on nearly all chain ends to give very narrow molecular weight distribution. All are cured in the same recipe, with 30 phr MT Black (N990), 3 phr zinc oxide, 3 phr TAIC, and 2 phr peroxide (Luperox 101-XL 45). The iodine-containing polymers were given only a two-hour oven post cure, while the GF with bromine cure sites was post cured for sixteen hours after the press cure at 177°C. With the improved processing of iodine-containing VDF/HFP/TFE elastomers, combined with better resistance to aqueous and polar fluids, these products are attractive alternatives to bisphenol-cured polymers for many uses, including automotive applications discussed in the next two chapters (Chs. 12 and 13).

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

255

Table 11.9 VDF/HFP/TFE Terpolymer Gum Elastomers

Trade Name

Viton[3]

Dyneon

66% Fluorine 60% VDF AL-300 AL-600 B-70

Composition 68% Fluorine 69% Fluorine 50% VDF 45% VDF B-202 B-600 FLS 2640Q FT 2430 FT 2481

FE 5522X FE 5542X

[4]

70%–71% F 36%–30% VDF

FE 5832X

G-211 G-501

Dai-el[5] Tecnoflon[12]

L 636

T 636 T 636L

Table 11.10 VDF/HFP/TFE Terpolymer Bisphenol Precompounds

Trade Name

AL-276C AL-576C

Viton[3]

Dyneon

66% Fluorine 60% VDF

VTR-9083 VTR-9084

Dai-el[5]

G-671

[13]

B-135C B-201C B-435C B-601C B-605C FE 5730 FT 2320 FT 2350 G-551 G-558

FE 5520X FE 5540X

[4]

Tecnoflon

Composition 68% Fluorine 69% Fluorine 50% VDF 45% VDF

T 838K

FOR 5381 FOR 9381 FOR 9382

70%–71% F 36%–30% VDF

F-605C

FE 5830Q FE 5840Q G-621

FOR 4391

256

FLUOROELASTOMERS HANDBOOK

Table 11.11 VDF/HFP/TFE Terpolymer Bisphenol Precompounds

Trade Name and Type

Compound Polymer MT Black (N990) Ca(OH)2 MgO (High Activity) VC-50 M1 M2 ODR at 177ºC, 3º Arc ML, N·m MH, N·m ts2, minutes tc90, minutes

Viton[14]

Viton[14]

AL-600

AL-300

97.5 30 6 3 2.5

97.5 30 6 3 2.5

Tecnoflon[15] L 636 100 30 6 3 4 1.5

2.3 13.6 1.8 3.4

Physical Properties Press cure 10 minutes at 232ºC 177ºC, post cure 24 hours at: Stress/strain at 23ºC – Original M100, MPa 6.6 TB, MPa 13.7 EB, % 205 Hardness, Shore A 70 Stress/strain at 23ºC – Heat aged After 70 hours at 250ºC TB change, % +17 EB change, % -2 Hardness change, points +4 Fluid resistance – Volume increase, % IRM-903 Oil, 70 h at 2.5 200ºC Fuel C, 168 h at 23ºC Compression Set, O-rings, % 70 h at 200ºC 14 Low Temperature Retraction TR-10, ºC -19

0.8 10.1 1.8 3.4

1.1 11.3 2.8 4.8

232ºC

250ºC

5.6 11.7 205 73

6.0 14.5 190 72

250ºC +10 -10 +2

275ºC +24 +6 -2

2.5 5 21

20

-19

-21

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

257

Table 11.12 Curing of VDF/HFP/TFE Terpolymer Precompounds (69% F)

Trade Name and Type [16]

Viton B-601C

Dyneon[17] FT 2350

Dai-el[18] G-551

Tecnoflon[19] FOR 9381

60

56

48

40

100

100

100

100

30

30

20

30

Ca(OH)2

6

6

6

6

MgO (High Activity)

3

3

3

3

Viscosity ML-10 (121°C) Compound Precompound MT Black (N990)

ODR at 177°C, 3° Arc ML, N·m

2.7

2.1

MH, N·m

12.9

9.6

ts2, minutes

2.9

2.5

tc90, minutes

6.9

4.2

Physical Properties Press cure, min/°C

10/177

5/177

10/170

10/177

Post cure, h/°C

24/232

24/260

24/230

24/250

M100, MPa

5.9

3.7

4.4

4.5

TB, MPa

13.8

15.2

15.9

16

EB, %

232

310

210

275

Hardness, Shore A

79

75

74

78

232°C

230°

275°C

TB change, %

+14

+1

-49

EB change, %

-20

-1

+60

Hardness change, points

+2

0

+3

36

25

30

-14

-14

-13

Stress/strain at 23°C – Original

Stress/strain at 23°C – Heat aged After 70 hours at

Compression Set, O-rings, % 70 h at 200°C

21

Low Temperature Retraction TR-10, °C

258

FLUOROELASTOMERS HANDBOOK

Table 11.13 Curing of VDF/HFP/TFE Terpolymer Precompounds (70%–71% F)

Trade Name and Type [20]

Viton F-605C

Dyneon[21] FE 5840Q

Dai-el[22] G-621

Tecnoflon[23] FOR 4391

60

37

50

40

100

100

100

100

30

30

20

30

Ca(OH)2

6

6

6

6

MgO (High Activity)

3

3

3

3

Carnauba Wax

1

Viscosity:ML-10 (121°C) Compound: Precompound MT Black (N990)

ODR at 177°C, 3° arc ML, N·m

2.4

1.2

MH, N·m

11.4

11

ts2, minutes

1.5

2.6

tc90, minutes

4.3

4.8

MDR at 177°C, 0.5° arc ML, N·m

0.23

0.17

MH, N·m

3.2

2.6

ts2, minutes

1.2

1.3

tc90, minutes

3.0

2.0

Physical Properties Press cure, min/°C

10/177

5/177

10/170

10/170

Post cure, h/°C

24/232

24/260

24/230

24/250

Stress/strain at 23°C – Original M100, MPa

6.1

6.8

3.7

6.3

TB, MPa

14.9

13.8

16.2

14.5

EB, %

250

210

280

207

Hardness, Shore A

77

84

76

80

250°C

230°C

250°C

TB change, %

-2

+5

-4

EB change, %

-18

-2

+18

Hardness change, pts

-1

0

+1

Stress/strain at 23°C – Heat aged After 70 hours at

(Cont’d.)

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

259

Table 11.13 (Cont’d.)

Trade Name and Type Viton Dyneon[21] Dai-el[22] F-605C FE 5840Q G-621 Stress/strain at 23°C – Aged in fuel C/Methanol (85/15) at 23°C for time, hours 168 TB change, % -28 EB change, % +12 Hardness change, points -10 Volume change, % +9 Compression set, O-rings, % 70 h at 200°C 30 26 29 Low Temperature Characteristics TR-10, °C -7 -8 DSC: Tg, °C -8 [20]

Tecnoflon[23] FOR 4391 70 -23 +5 -6 +6 24

Table 11.14 Peroxide-Curable VDF/HFP/TFE Fluoroelastomers

Trade Name

Viton[24][25]

Dai-el

Composition 68%–69% Fluorine 70%–71% Fluorine 50%–45% VDF 36%–30% VDF GBL-900 GF GBL-200 GF-300 GBL-S GF-S

[5]

G-952

Dyneon[4] Tecnoflon[26]

11.3 VDF/PMVE/TFE Compounds As discussed in Ch. 2, VDF/PMVE/TFE polymers have significantly better low-temperature characteristics than VDF/HFP/TFE polymers. From Figs. 2.5 and 2.6, VDF/PMVE/TFE polymers have glass transition temperatures and TR-10 temperatures some 12°C to 15°C lower than those for VDF/HFP/

P 457 P 757

G-901 G-902 G-912 FLS 2650 P 459 P 959

TFE polymers with the same VDF content. It should be noted that, at the same VDF level, PMVE-containing polymers have lower percent fluorine by 2%– 3% absolute. Fluid swell correlates better with VDF content than fluorine content. Commercial VDF/ PMVE/TFE fluoroelastomers contain bromine and/ or iodine cure sites to allow peroxide curing in the same manner as that discussed above for VDF/HFP/ TFE polymers.

260 Since the main emphasis has been on low-temperature characteristics, the major VDF/PMVE/TFE fluoroelastomers have low fluorine content, (64%– 65%) with VDF near 55% to get TR-10 to about 30°C. These compounds can give satisfactory static seal performance at -40°C. Polymers with higher fluorine content are also offered to get better fluid resistance. Available commercial polymers are listed in Table 11.16. Cure characteristics and vulcanizate properties of 65% fluorine elastomers are shown in Table 11.17. The original peroxide-curable VDF/PMVE/TFE polymer, Viton GLT, has high molecular weight and cure sites distributed along chains from incorporated bromine-containing cure-site monomer. Vulcanizates have good thermal resistance (capable of long-term service at 230°C), and good low-temperature flexibility. A number of end-use specifications were based on GLT characteristics. Thus, several competitive products were developed with about the same composition, to meet these requirements. Viton GLT cures relatively slowly, and mold release is deficient. The other products in Table 11.17 are based on iodine cure sites to give faster cures and better mold release. The Daikin product, Dai-el LT-303, apparently contains iodine cure sites only at chain ends; thermal resistance is lower than that of GLT. With network tie points only at chain ends, relatively little chemical degradation of crosslinks results in considerable loss of physical properties. Polymers with more than two cure sites per chain can withstand more chemical degradation without much loss of properties. Viton® GLT-S and Tecnoflon® PL 855 exemplify such materials. All polymers with iodine cure sites cure rapidly and completely in the press; little or no oven post cure is required to develop good compression set and other physical properties. As shown in Table 11.16, peroxide-curable VDF/ PMVE/TFE fluoroelastomers are available with higher fluorine content to get better fluid resistance with good low-temperature characteristics. Highfluorine products are compared in Table 11.18. Curing and vulcanizate properties of these highfluorine fluoroelastomers are similar to those of VDF/ PMVE/TFE polymers with lower fluorine content, but fluid resistance is greater. A number of the fluoroelastomers described in this chapter are discussed further in the next two chapters on automotive applications.

FLUOROELASTOMERS HANDBOOK

11.4 Seal Design Considerations Even with the proper choice of fluoroelastomer compound for a particular seal application, including consideration of temperatures and fluid environments to be encountered, the sealing system must be properly designed to function satisfactorily. For high-temperature sealing applications, special allowance must be made for the high thermal expansion of fluoroelastomers and their considerable tendency to soften at high temperatures. When seals must function at temperatures below about -20°C, care must be taken in choosing proper compounds, since low-temperature flexibility of many fluoroelastomers is marginal. A number of mechanical design problems can lead to seal failure, as listed in Table 11.19.[33] Several general rules apply for elastomeric seals,[23] based on finite element analysis and practical experience. Compression or strain should not exceed 25%, since higher compression can lead to local strains sufficient to cause elastomer failure and cracking of the seal. Nominal o-ring compression of about 18% is sufficient for most applications. Lower compression, about 11%, is adequate for gaskets. O-rings seated in grooves should not be stretched by more than 5% of original inside diameter. These are only a few basic factors that must be taken into account for successful seal design.

11.5 Additional Fluoroelastomer Molding Compounds Curing characteristics and vulcanizate properties for a number of fluoroelastomers are listed in the appended tables from The Rubber Formulary, a previous book in the Plastics Design Series[34] Included are compounds for o-rings, molded goods, injection molding, low hardness, no post cure, and low-temperature applications. Many of these have been listed in earlier sections of this chapter; in particular, see Tables 11.2, 11.8, 11.10, 11.14, and 11.16 to determine compositions and general characteristics of the types described in the appended tables.

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

261

Table 11.15 Peroxide Curing of High-Fluorine VDF/HFP/TFE Fluoroelastomers with Different Cure Sites[24]

Viton ® GF

GF-300

GF-S (VTR-8600)

Monomer

Br

Br

I

End groups

--

I

I

ML, dN·m

2.0

0.7

1.9

MH, dN·m

13.2

22.4

30.4

ts2, minutes

0.6

0.5

0.4

tc50, minutes

1.0

0.6

0.6

tc90, minutes

3.4

1.2

0.9

16

2

2

M100, MPa

7.0

5.4

5.4

TB, MPa

20.4

16.8

20.7

EB, %

214

227

269

Hardness, Shore A

72

72

72

Cure Sites

MDR at 177°C, 0.5° arc

Physical Properties at 23°C – Original Press cure – 7 minutes at 177°C, post cure – Hours at 232°C

Compression Set, O-rings, % After 22 hours at 200°C No post cure

69

43

19

Post cured

37

27

17

TB change, %

-0.3

+10.6

-0.6

EB change, %

+15

+27

+10

Hardness change, points

+1

+1

0

Physical Properties at 23°C – Aged in ASTM 105 Oil (5W/30) After 168 hours at 150°C TB change, %

-37

-20

-34

EB change, %

-28

-19

-35

Hardness change, points

+3

+2

+1

Volume swell, %

1.5

1.3

1.1

Fuel C, 168 hours at 23°C

1.6

1.3

1.2

Methanol, 168 hours at 23°C

3.9

2.5

2.4

Water, 168 hours at 100°C

7.9

4.8

3.7

Volume swell, %, after immersion

262

FLUOROELASTOMERS HANDBOOK

Table 11.16 VDF/PMVE/TFE Fluoroelastomers

Composition

TR-10, °C

64%–65% Fluorine

66% Fluorine

67% Fluorine

52%–56% VDF

45%–50% VDF

36%–40% VDF

-30

-26

-24

Trade Name GLT Viton[3][27]-[29]

GLT-305

GFLT GBLT-S

GLT-S Dai-el[5] Tecnoflon[12]

GFLT-S

LT-302

LT-252

LT-303

LT-271

PL 455 PL 855

GFLT-301

PL 956

PL 458 PL 958

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

263

Table 11.17 Peroxide Curing of VDF/PMVE/TFE Fluoroelastomers (65% F)

Viton[27] GLT

Trade Name and Type Viton[27] Dai-el[30] GLT-S LT-303 (VTR-8500)

Recipe, phr: MT Black (N990) 30 30 Zinc Oxide 3 3 TAIC 3 3 Peroxide (100% A.I.) 1.4 1.4 Curing at 177°C MDR 2000, 0.5° ODR, 3° arc ML, N·m 0.3 0.2 MH, N·m 1.8 2.7 ts2, minutes 0.6 0.4 tc90, minutes 3.2 0.8 Physical Properties – Original Press cure, minutes/°C 7/177 7/177 Post cure, hours/°C 16/232 2/232 M100, MPa 5.9 3.6 TB, MPa 17.6 17.8 EB, % 181 267 Hardness, Shore A 67 67 Low Temperature Characteristics TR-10, °C -31 -31 Compression Set, O-rings, % 70 h at 200°C – Post cured 22 h at 200°C – No post cure 31 16 22 h at 200°C – Post cured 16 11 Physical Properties – Heat aged After 70 h at temp., °C 250 250 TB change, % -2 +5 EB change, % +11 +23 Hardness change,point +2 +1 Fluid resistance - % volume swell after immersion ASTM 105 Oil (5W/30), 168 h at 150°C 1.6 1.0 Fuel C, 168 h at 23°C 7.2 7.5 M15 (85/15 Fuel C/Methanol), 168 h at 23°C 31 33 Water, 168 h at 100°C 4.8 2.4

30 -3 1.5

Tecnoflon[31] PL 855

30 5 3 0.9 1.5 14.7 0.9 2.0

10/160 4/180 2.6 18.0 350 69

10/177 1/230 5.0 20.1 240 67

-32

-30

25

24

230 -15 -9 +1

264

FLUOROELASTOMERS HANDBOOK

Table 11.18 Peroxide Curing of VDF/PMVE/TFE Fluoroelastomers (65% F)

Trade Name and Type Viton[29] Viton[29] Tecnoflon[32] GFLT-S GFLT-600 PL 958 (VTR-8550) Recipe, phr: MT Black (N990) 30 Zinc Oxide 3 TAIC 3 Peroxide, Luperco 101 XL (45% A.I.) 3 Curing – MDR 200, 0.5° arc Temperature, °C 177 ML, dN·m 2.0 MH, dN·m 19 ts2, minutes 0.5 tc90, minutes 3.1 Physical Properties – Original Press cure, minutes/°C 7/177 Post cure, hours/°C 16/232 M100, MPa 9.5 TB, MPa 11.6 EB, % 147 Hardness, Shore A 72 Low Temperature Characteristics TR-10, °C -23 Compression Set, O-rings, % 70 h at 200°C – Post cured 22 h at 200°C – No post cure 46 22 h at 200°C – Post cured 26 Physical properties – Heat aged after 70 h at 250°C TB change, % -6 EB change, % +16 Hardness change, points -1 Fluid resistance - % volume swell after immersion Fuel C, 168 h at 23°C 4.2 M15 (85/15 Fuel C/Methanol), 168 h at 23°C 13 Methanol, 168 h at 23°C 8.4 Water, 168 h at 100°C 7.9

30 3 3 3

30 5 3 3

177 2.0 33 0.4 0.8

170 1.9 37 0.5 1.2

7/177 2/232 6.6 12.3 207 71

6/170 1/230 8.5 21.2 185 73

-24

-24 17

13 11 -6 +22 0 4.5 14 8.9 2.5

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

265

Table 11.19 Common Seal Failure Modes[33]

Common Seal Failure Modes Cause

Effect

Sharp corners, acute angles

Rupture as seal flexes under pressure or by thermal expansion

Poor surface finish

Leakage of gases

Excessive cavity tolerance

Weeping of seal

Insufficient seal compression

Leakage at low temperature; gas leakage at low pressures

High seal compression

Seal splitting at high temperature

Poor fitting technique

Twisted o-ring sections, leakage

Cavity volume inadequate for thermal and fluid expansion

Extrusion of seal

Lack of back-up rings

Extrusion of seal at high pressure

266

FLUOROELASTOMERS HANDBOOK

Table 11.20 O-Ring General Purpose, Injection Molding Molding (MIL-R-83248) - Ausimont[34]

Specification Tecnoflon FORv 423/U

Type I (-214 O-rings) 100

Magnesium Oxide (high activity)

3

Calcium Hydroxide

6

MT N-990 Carbon Black

30

Physical Properties (press cure 10 minutes @ 170°C, post cure 8 hours + 16 hours @ 25°C) Hardness, Shore A, points Tensile Strength, psi Elongation, %

75 ± 5

74

1,400 min

1,615

125 min

200

Compression Set (-214 O-rings) 22 hours @ 200°C, %

15 max

10.5

166 hours @ 175°C, %

20 max

12.5

Chemical Resistance (immersion 70 hours @ 23°C, Reference Fuel TT-S-735 Type III) Hardness Change, points

±5

-1

Tensile Change, %

-20 max

-10

Elongation Change, %

-20 max

-7

Volume Change, %

0.5 to 10

1.4

Chemical Resistance (immersion 70 hours @ 175°C, Reference Oil AMS 3021) Hardness Change, points

-15 to 0

-8

Tensile Change, %

-30 max

-20

Elongation Change, %

-20 max

+5

Volume Change, %

1 to 20

+14

Compression Set, %

10 max

4

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

267

Table 11.21 O-Ring Applications – Dyneon[34]

Formulation 1

2

3

4

Recipe Fluorel™ FE-5610Q*

100

Fluorel FE-5620Q*

100

Fluorel FE-5621Q*

100

Fluorel FE-5623Q*

100

MT Black (N990)

30

30

303

30

MgO

3

3

3

3

Ca(OH)2

6

6

6

6

Physical Properties (press cure 10 min. @ 177°C, post cure 24 hours @ 260°C) %F

65.9

S.G.

1.80

1.80

1.80

1.80

9

23

23

23

TR 10 (°C)

-18

-18

-18

-18

Tensile (psi)

1930

2240

2240

2400

Elongation (%)

210

195

195

180

M100 (psi)

800

950

950

1060

Durometer, Shore A (pts)

75

77

77

79

Compression Set, ASTM D395, Method B, 70 hours @ 200°C

21

13

13

13

Mooney Visc. (1 + 10) @ 121°C

65.9

65.9

65.9

Rheological Properties (Monsanto MDR2000™, 100 cpm, 0.5° arc, 6 min) 177°C (350°F) ML (in-lbs)

0.3

0.7

0.7

0.7

ts2 (min)

2.7

2.3

2.3

104

t´50 (min)

3.0

2.6

2.6

1.6

t´90 (min)

4.2

3.7

3.7

2.3

15.6

22.4

22.4

23.0

ML (in-lbs)

0.3

0.5

0.5

0.5

ts2 (min)

1.2

0.8

0.8

0.4

t´50 (min)

1.3

0.9

0.9

0.5

t´90 (min)

1.5

1.1

1.1

0.7

14.0

21.0

21.0

21.0

MH (in-lbs) 200°C (392°F)

MH (in-lbs) *Incorporated cure polymer

268

FLUOROELASTOMERS HANDBOOK

Table 11.22 O-Ring Applications – Dyneon[34]

Formulation 5

6

7

8

Recipe Fluorel™ FE-5640Q*

100

Fluorel FE-5641Q*

100

Fluorel FE-5660Q*

100

Fluorel FE-5840Q* MT Black (N990)

100 30

30

303

30

MgO

3

3

3

Ca(OH)2

6

6

6

Physical Properties (press cure 10 min. @ 177°C, post cure 24 hours @ 260°C) %F

65.9

65.9

65.9

70.1

S.G.

1.80

1.80

1.80

1.86

Mooney Visc. (1 + 10) @ 121°C

40

40

60

37

TR 10 (°C)

-18

-18

-18

-18

Tensile (psi)

2370

2340

2400

2000

Elongation (%)

200

185

200

210

M100 (psi)

1050

970

1150

980

Durometer, Shore A (pts)

77

76

77

84

Compression Set, ASTM D395, Method B, 70 hours @ 200°C

11

11

9

26

Rheological Properties (Monsanto MDR 1000™, 100 cpm, 0.5° arc, 6 min) 177°C (350°F) ML (in-lbs)

1.5

1.4

2.3

1.7

ts2 (min)

21

2.2

1.9

1.3

t´50 (min)

2.7

2.8

2.6

1.6

t´90 (min)

3.7

3.8

3.5

2.0

MH (in-lbs)

24.8

24.4

26.3

26.6

ML (in-lbs)

1.3

1.2

2.3

1.7

ts2 (min)

0.7

0.6

0.6

0.4

t´50 (min)

0.8

0.7

0.7

0.5

t´90 (min)

1.0

0.8

0.8

0.6

MH (in-lbs)

21.7

20.4

24.4

24.0

200°C (392°F)

*Incorporated cure polymer

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

269

Table 11.23 O-Ring Applications – Dyneon[34]

Formulation 9

10

11

12

13

Recipe Fluorel™ FC-2110Q*

100

Fluorel FC-2121*

100

Fluorel FC-2174*

100

Fluorel FC-2179*

100

Fluorel FC-2180*

100

MT Black (N990)

30

30

303

30

30

MgO

3

3

3

3

3

Ca(OH)2

6

6

6

6

6

Physical Properties (press cure 10 min @ 177°C, post cure 24 hours @ 260°C) %F

65.9

65.9

65.9

65.9

65.9

S.G.

1.80

1.80

1.80

1.80

1.80

9

23

40

80

40

TR 10 (°C)

-18

-18

-18

-18

-18

Tensile (psi)

2010

2375

2450

2475

2370

Elongation (%)

170

180

180

180

180

M100 (psi)

950

1025

1050

1100

1025

Durometer, Shore A (pts)

77

77

78

76

75

Compression Set, ASTM D395, Method B, 70 hours @ 200°C

19

14

12

10

12

Mooney Visc. (1 + 10) @ 121°C

Rheological Properties (Monsanto MDR 2000™, 100 cpm, 0.5° arc, 6 min) 177°C (350°F) ML (in-lbs)

0.3

0.8

1.5

3.6

1.5

ts2 (min)

1.5

1.4

1.1

1.3

1.3

t´50 (min)

1.7

1.7

1.4

1.9

1.5

t´90 (min)

2.7

2.4

1.9

2.5

2.1

MH (in-lbs)

16.6

23.3

25.0

28.7

25.5

200°C (392°F) ML (in-lbs)

0.7

ts2

0.5

t´50

0.6

t´90

0.8

MH (in-lbs) *Incorporated cure polymer.

21.0

270

FLUOROELASTOMERS HANDBOOK

Table 11.24 Molded Good Applications – Dyneon[34]

Formulation 1

2

3

Recipe Fluorel™ FE-5622*

100

Fluorel FE-5642Q*

100

Fluorel FE-5840Q*

100

MT Black (N990)

30

30

303

MgO

3

3

3

Ca(OH)2

6

6

6

Physical Properties (press cure 10 min @ 177°C, post cure 24 hours @ 260°C) %F

65.9

65.9

70.2

S.G.

1.80

1.80

1.86

Mooney Visc. (1 + 10) @ 121°C

22

40

37

TR 10 (°C)

-18

-18

-7

Tensile (psi)

2250

2312

2000

Elongation (%)

235

220

210

M100 (psi)

640

690

980

Durometer, Shore A (pts)

74

72

84

Compression Set, ASTM D395, Method B, 70 hours @ 200°C

18

17

26

Rheological Properties (Mossanto MDR 2000™, 100 cpm, 0.5°C, 6 min) 177°C (350°F) ML (in-lbs)

0.8

1.5

1.7

ts2 (min)

2.2

1.4

1.3

t´50 (min)

2.8

1.8

1.6

t´90 (min)

4.5

2.7

2.0

MH (in-lbs)

15.3

4

26.6

200°C (392°F) ML (in-lbs)

0.6

1.2

1.7

ts2 (min)

0.7

0.6

0.4

t´50 (min)

0.9

0.7

0.5

t´90 (min)

1.3

0.9

0.6

13.1

16.0

24.0

MH (in-lbs) *Incorporated cure polymer.

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

271

Table 11.25 Molded Goods Applications – Dyneon[34]

Formulation 1

2

3

4

Recipe Fluorel™ FC-2122*

100

Fluorel FC-2123*

100

Fluorel FC-2144*

100

Fluorel FC-2152* MT Black (N990)

100 30

30

30

303

MgO

3

3

3

3

Ca(OH)2

6

6

6

6

Physical Properties (press cure 10 min @ 177°C, post cure 24 hours @ 260°C) %F

65.9

65.9

65.9

65.9

S.G.

1.80

1.80

1.80

1.80

Mooney Visc. (1 + 10) @ 121°C

25

25

41

51

TR 10 (°C)

-18

-18

-18

-18

Tensile (psi)

1900

2350

2540

2100

Elongation (%)

310

270

260

305

M100 (psi)

520

530

550

550

Durometer, Shore A (pts)

75

71

70

73

Compression Set, ASTM D395, Method B, 70 hours @ 200°C

25

20

17

22

Rheological Properties (Monsanto MDR 2000™, 100 cpm, 0.5°C, 6 min) 177°C (350°F) ML (in-lbs)

0.9

0.9

1.5

2.2

ts2 (min)

1.2

1.2

0.9

1.0

t´50 (min)

1.4

1.6

1.2

1.3

t´90 (min)

2.1

2.8

1.9

1.8

12.1

12.2

15.2

15.6

ML (in-lbs)

0.8

0.7

ts2

0.5

0.5

t´50

0.6

0.6

t´90

0.8

1.2

MH (in-lbs)

9.4

10.1

MH (in-lbs) 200°C (392°F)

*Incorporated cure polymer.

272

FLUOROELASTOMERS HANDBOOK

Table 11.26 Molded Goods Applications – Dyneon[34]

Formuation 5

6

7

8

Recipe Fluorel™ FC-2176*

100

Fluorel FC-2177*

100

Fluorel FC-2181*

100

Fluorel FC-2530*

100

MT Black (N990)

30

30

30

303

MgO

3

3

3

3

Ca(OH)2

6

6

6

6

Physical Properties (press cure 10 min @ 177°C, post cure 24 hours @ 260°C) %F

65.9

65.9

65.9

69.0

S.G.

1.80

1.80

1.80

1.85

Mooney Visc. (1 + 10) @ 121°C

30

33

44

38

TR 10 (°C)

-18

-18

-18

-8

Tensile (psi)

2175

1965

2560

2200

Elongation (%)

240

240

240

255

M100 (psi)

600

700

690

700

Durometer, Shore A (pts)

71

75

72

77

Compression Set, ASTM D395, Method B, 70 hours @ 200°C

22

21

13

19

Rheological Properties (Monsanto MDR 2000™, 100 cpm, 0.5°C, 6 min) 177°C (350°F) ML (in-lbs)

1.1

1.6

1.6

1.4

ts2 (min)

1.1

1.8

1.0

1.5

t´50 (min)

1.3

2.5

1.2

1.9

t´90 (min)

2.0

4.3

1.7

2.6

14.5

15.1

18.5

20.2

MH (in-lbs) 200°C (392°F) ML (in-lbs) ts2 t´50 t´90 MH (in-lbs) *Incorporated cure polymer.

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

273

Table 11.27 Fluoroelastomer Molded Goods – Ausimont (now Solvay Solexis)[34]

Recipe Tecnoflon FFOR 5351/U

100

Magnesium Oxide (high activity)

3

Calcium Hydroxide

6

MT N-990 carbon black

30

Physical Properties (press cure 10 min @ 170°C, post cure 8 hours + 16 hours @250°C) Hardness Shore A, points

75

Tensile Strength, psi

2322

Elongation, %

240

100% Modulus, psi

653

Compression set (-214 o-rings) 20 hours @ 200°C, %

18

Table 11.28 Injection Moldable – DuPont Dow[34]

Recipe Viton A-200

97.5

Calcium Hydroxide

6

N-990

30

Maglite D

3

VPA #3

1

Viton Curative #50

2.5 Total

140

Expected Physical Properties - Original Tensile Strength, psi

1800

Elongation, %

190

Hardness, Shore A

77

Compression Set 70 hours @ 200°, %

12

274

FLUOROELASTOMERS HANDBOOK

Table 11.29 Low Hardness Fluoroelastomer Articles – Ausimont (now Solvay Solexis)[34]

Recipe Tecnoflon FOR LHF

100

Magnesium Oxide (high activity)

1.5

Calcium Hydroxide

1.5

Barium Sulfate

5.0

Physical Properties (press cure 10 min @ 170°C, post cure 8 hours + 16 hours @ 250°C) Hardness Shore A, points

45

Tensile Strength, psi

725

Elongation, %

360

100% modulus, psi

145

Brittle point, °C

-40

Compression Set (-214 O-rings) 70 hours @ 200°C, % Heat aging (168 hours @ 250°C Hardness change, points

-2

Tensile change, %

+5

Elongation change, %

+25

Chemical Resistance (Immersion 168 hours @ 23°C, Reference Fuel C) Volume change, %

+5

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

275

Table 11.30 No Postcure Fluoroelastomer Articles – Ausimont (now Solvay Solexis)[34]

Formulation 1

2

Recipe Tecnoflon P757

100

Tecnoflon P959

100

Luperco 101XL

3

3

TAIC, 75% Dispersion

4

4

Zinc Oxide

5

5

MT N-990 carbon black

30

30

67

71

Tensile strength, psi

2354

2454

Elongation, %

320

259

100% Modulus, psi

462

650

Compression Set (-214 O-rings) 70 hours @ 200°C, %

33

29

Physical Properties (press cure 10 min @170°C) Hardness Shore A, points

Chemical Resistance (immersion 168 hr @ 150°C, press cure 10 min @ 170°C) SH Motor oil Hardness change, points

+2.5

+5

Tensile change, %

+8

+7

Elongation change, %

+2

-3

Volume change, %

-0.7

-0.6

Hardness change, points

+0.1

-0.5

Tensile change, %

-11

+4

Elongation change, %

-9

-1

+0.1

-0.1

+2.7

+2.2

Tensile change, %

-8

-3

Elongation change, %

-9

+2

+0.1

-0.1

+0.7

+0.4

Tensile change, %

+1

+17

Elongation change, %

-3

+9

+1.2

+0.2

Engine Coolants

Volume change, % ATF Hardness change, points

Volume change, % Synthetic Gear Oil Hardness change, points

Volume change, %

276

FLUOROELASTOMERS HANDBOOK

Table 11.31 Low Temperature – DuPont Dow[34]

Recipe Viton GLT

100

Calcium Hydroxide

3

N-990

30

VPA #3

1

DIAK #8

0.8

RC-R-6156

0.2

Lupercol 101XL

3 Total

138

Expected Physical Properties - Original Tensile Strength, psi

2540

Elongation, %

180

Hardness, Shore A

70

Compression Set 70 hours @ 150°C, %

22

Table 11.32 Low Temperature Fluoroelastomer Service Seals – Ausimont (now Solvay Solexis)[34]

Recipe Tecnoflon P710

100

Luperco 101XL

3

TAIC, 75% Dispersion

4

Zinc Oxide

5

MT N-990 carbon black

30

Physical Properties (press cure 10 min @ 177°C, post cure 8 hr + 16 hours @ 230°C) Hardness Shore A, points Tensile Strength, psi

69 2760

Elongation, %

200

100% modulus, psi

815

Compression set (-214 O-rings) 70 hr @ 200°C, %

35

Low Temperature Properties TR10, °

-30

TR30, °

-26

TR50, °

-24

11 COMPOUNDS FOR O-RINGS AND MOLDED GOODS

277

REFERENCES 1. Viton® A-401C, DuPont Product Information Bulletin VT-220.A401C (1992) 2. R. D. Stevens, “Permeation and Stress Relaxation Resistance of Elastomeric Fuel Seal Materials,” paper 2001-01-1127 given at SAE 2001 World Congress, Detroit, Michigan (March 5-6, 2001) 3. Viton® Fluoroelastomer Selection Guide, DuPont Dow Technical Information (September 1998) 4. Dyneon™ Fluoroelastomers, Product Listing, www.Dyneon.com (June 2004) 5. Dai-el™ Fluoroelastomer, Product Listing, www.daikin-america.com (June 2004) 6. Tecnoflon Fluoroelastomer Product Data Sheet, Recommended Grades for Low Compression Set, www.solvaysolexis.com (November 2003) 7. Dyneon™ Fluoroelastomers, Compounding Fluoroelastomers, Dyneon Technical Information Bulletin 98-0504-1324-8 (January 2001) 8. A. L. Moran, Compounding with Viton Curative Masterbatches, DuPont Viton Bulletin VT-310.1 (1978) 9. Viton® A-700, DuPont Dow Technical Information (January 2002) 10. Tecnoflon Fluoroelastomer Product Data Sheet, Recommended Grades Non-cure Containing, www.solvaysolexis.com (November 2003) 11. Tecnoflon Fluoroelastomer Product Data Sheet, Recommended Grades for Molded Goods, www.solvaysolexis.com, November 2003 12. Tecnoflon Fluoroelastomer Product Data Sheet, Recommended Grades Low Temperature Polymers, www.solvaysolexis.com (November 2003) 13. Tecnoflon Fluoroelastomer Product Data Sheet, Recommended Grades Terpolymers, www.solvaysolexis.com (November 2003) 14. Viton® AL-600, DuPont Dow Technical Information Bulletin (February 2003) 15. Tecnoflon L 636, Product Data Sheet, Solvay Solexis (December 2002) 16. Viton® B-601C, DuPont Dow Technical Information (February 2003) 17 Dyneon™ Fluoroelastomer FT 2350, Dyneon Technical Information Bulletin (January 2001) 18. Dai-el™ Fluoroelastomer G-551, Daikin Technical Information Bulletin ER-002 AK (November 2001) 19. Tecnoflon FOR 9381, Product Data Sheet, Solvay Solexis (March 2003) 20. Viton® F-605C, DuPont Dow Technical Information (February 2003) 21. Dyneon™ Fluoroelastomer FT 5840Q, Dyneon Technical Information Bulletin (December 2000) 22. Dai-el™ Fluoroelastomer G-621, Daikin Technical Information Bulletin ER-171 AK (November 2001) 23. Tecnoflon FOR 4391, Product Data Sheet, Solvay Solexis (December 2002) 24. Viton® VTR-8600 – A New Peroxide Cured GF Polymer, DuPont Dow Technical Information (December 2002) 25. Viton® VTR-8650 – A New Peroxide Cured GBL Polymer, DuPont Dow Technical Information (December 2002) 26. Tecnoflon Fluoroelastomer Product Data Sheet, Recommended Grades Peroxide Curable Polymers, www.solvaysolexis.com (November 2003) 27. Viton® VTR-8500 – A New Peroxide Cured GLT Polymer, DuPont Dow Technical Information (December 2002) 28. Viton® VTR-8525 – A New Peroxide Cured GBLT Polymer, DuPont Dow Technical Information (February 2003)

278

FLUOROELASTOMERS HANDBOOK

29. Viton® VTR-8550 – A New Peroxide Cured GFLT Polymer, DuPont Dow Technical Information (February 2003) 30. Dai-el™ Fluoroelastomer LT-303, Daikin Technical Information Bulletin ER AK (June 2003) 31. Tecnoflon P L 855, Product Data Sheet, Solvay Solexis (December 2002) 32. Tecnoflon P L 958, Product Data Sheet, Solvay Solexis (December 2002) 33. Viton® - Excelling in Modern Automotive Fuel Systems, DuPont Dow Technical Bulletin H-82107 (March 1999) 34. P. A. Ciullo and N. Hewitt, The Rubber Formulary, PDL Handbook Series, The Formulary IX. Silicone & Fluoroelastomers, pp. 649-669, Noyes Publications/William Andrew Publishing, Norwich, New York (1999)

12 Compounds for Auto Fuel Systems 12.1 Introduction The modern automotive fuel system must meet a number of stringent requirements. The fuel system must deliver a highly flammable fluid from the fill cap to the tank, then from the tank to the fuel rail at the engine, and then back, with precision and safety.[1] Fuel losses to the environment must be minuscule. The fuel system contains many elastomeric components, including o-rings, grommets, gaskets, hose, and tubing. Each of the components must be sealed at joints with negligible leaks in a robust, longlasting design. Environmental regulations are becoming more stringent.[1] In the U.S., the California Air Resources Board (CARB) has enacted the Low Emissions Vehicle II (LEV II) program, which requires that hydrocarbon evaporative emissions be reduced to 0.5 grams in a 24-hour average in 2004. These new limits must be met for 15 years or 150,000 miles (240,000 km). The U.S. Environmental Protection Agency (EPA) has passed similar rules, requiring evaporative emissions be reduced to 0.95 grams in 24 hours. Also, the EPA has asked for certification of 10% ethanol-containing fuels as well as regular unleaded gasoline, and requires the performance be maintained for 12 years or 120,000 miles

Figure 12.1 Fluoroelastomers in fuel systems.[2]

(192,000 km). In Europe, control of evaporative emissions is becoming more stringent, with Euro IV limits starting in 2004. Fluoroelastomer components are used in many components of modern automotive fuel systems, as indicated in Fig. 12.1.[2] Fluoroelastomers are used in several fuel tank components, including the filler system and fuel pump. The fuel line includes a number of fluoroelastomer seals along with sections of fuel hose. At the engine, fluoroelastomer o-rings are used in fuel injectors, and also in seals for emission control components. Other elastomers are not sufficiently resistant to many of the fuel compositions; their high permeability would lead to excessive emissions. Also, elastomers other than fluoroelastomers do not provide adequate seal lifetime to meet the automotive service requirements noted above. Fuel compositions vary widely. Hydrocarbon mixtures contain various ratios of aliphatic and aromatic components, with volatility varying with the season of the year. Unlike hydrocarbon elastomers, fluoroelastomers are generally resistant to all hydrocarbon compositions. Oxygenated fuels contain alcohols (methanol or ethanol) or ethers (methyl tertiary-butyl ether [MTBE] or ethyl t-butyl ether) which may require fluoroelastomers with high

280

FLUOROELASTOMERS HANDBOOK

fluorine content for adequate fluid resistance. Partially oxidized fuel (“sour” fuel), containing hydroperoxides formed after air exposure, attacks hydrocarbon elastomers, but has little effect on fluoroelastomers.[1] These considerations will be discussed in the following sections on various parts of the automotive fuel system.

12.2 Fuel Line Veneer One of the first applications for fluoroelastomers in fuel systems was in fuel line hose, a composite with an inner veneer of fluoroelastomer as a barrier layer, as shown in Fig. 12.2. The fluoroelastomer veneer is coated on a mandrel (usually an EPDM cable of proper diameter) in a cross-head die and drawn to a thickness of 12–30 mil (0.3 mm–0.8 mm). Additional tie layer, reinforcement, and cover layer are then extruded before curing in an autoclave. Several low-viscosity fluoroelastomers with varying fluorine content have been developed with good veneer extrusion characteristics. Recently, bimodal polymers have been developed for outstanding extrusion performance. The cost of the fluoroelastomer veneer hose construction is relatively high, so much of the fuel line in most automobiles is metal or thermoplastic tubing, with relatively short sections of fluoroelastomer veneer hose. Elastomeric sections are required for sections with intricate bends, and reduced noise and vibrations. Fluoroelastomer seals are also required for junctions at the ends of metal or thermoplastic sections of tubing. The main requirement for the inner veneer layer of a fuel hose is permeation resistance. In permeation, fuel components dissolve at the inner surface according to solubility equilibria, and then diffuse through the thin elastomer layer according to Fick’s Laws.[3] For steady state permeation through a membrane, the following equation applies: Eq. (12.1)

q/t = QAP0/h

In Eq. 12.1, the permeation rate is q/t, usually expressed as quantity q grams of component diffusing in time t days through a membrane with surface area A in meters squared and thickness h in millimeters. The permeation coefficient Q is defined by the

Figure 12.2 Fuel line hose.[2]

product Ds of the diffusion coefficient D and solubility coefficient s. The component solubility is sP0, where P0 is the vapor pressure of the component at the high-pressure surface of the membrane. Permeation measurements are reported according to the equation rearranged in the form: Eq. (12.2)

(q/t)·h/A = DsP0

Thus the steady-state permeability reported in g·mm/m2·day depends on component diffusivity and solubility in the membrane. For amorphous elastomer compounds, the diffusivity of a fluid does not vary much with the composition of the elastomer. Permeability thus depends largely on the fluid solubility in the elastomer, so permeability correlates well with fluid swell measurements. For glassy or highly crystalline thermoplastics, diffusivity varies considerably with the membrane material composition. Since all the parameters on the right-hand side of Eq. 12.2 follow an Arrhenius relationship for temperature de-

12 COMPOUNDS FOR AUTO FUEL SYSTEMS pendence, permeability also follows a relationship of the form: Eq. (12.3) (q/t)·h/A = [(q/t)·h/A]0 exp(-Ea /RT) A plot of log(permeability) versus 1/T (with temperature T in kelvins) should yield a straight line of slope -Ea /R. Fuel permeability through rubber or plastic sheet can be measured using a modified ASTM E96-66 Thwing Albert cup permeation test method, as shown in Fig. 12.3.[2] Usually the testing is done at room temperature, but may also be carried out at elevated temperatures. While the method calls for determination of steady-state permeation rate, this is not always possible when testing fuel mixture permeation through highly permeable materials.[1] The cup is loaded with a single 100-mL charge of fuel mixture that is put in contact with the test diaphragm for a total of 21 days, with periodic determinations of weight loss. If the permeation rate is high, especially for one or more components of a fuel mixture, the fuel composition changes over the course of the test period. Thus, the test is useful for comparison of materials, but is only reliable for quantitative permeability values when the fraction of fuel lost through the diaphragm is low (i.e., the material being tested has low permeability).

Figure 12.3 Thwing Albert permeation test procedure.[2]

281 Permeation rates determined by the Thwing Albert cup test using M15 fuel with a variety of elastomers and thermoplastics used in fuel systems are shown in Table 12.1.[1] M15 fuel contains 15% methanol blended in 85% Fuel C (a 50/50 mixture of isooctane and toluene). The elastomers tested include nitrile rubber (NBR with 33% acrylonitrile content), hydrogenated nitrile rubber (HNBR with 44% acrylonitrile), fluorosilicone (FVMQ), fluoroelastomers FKM-A (66% F), FKM-B (69% F), and FKM-GF (70% F). Thermoplastics tested include nylon 12 polyamide, Dyneon® THV500 (VDF/HFP/ TFE crystalline thermoplastic), Tefzel® ETFE (ethylene/TFE copolymer), and Teflon® FEP (TFE/HFP copolymer). In these tests, the exposed diaphragm area A = 3.83 × 10-3 m2 (inside diameter of cup is 69.85 mm), and the diaphragm thickness was probably about 0.75 mm, so permeability values greater than 100 g·mm/m2·day correspond to weight losses greater than 0.5 g/day and more than 10 g total out of the initial charge of about 75 g fuel mixture. Such large losses would significantly change the composition of the fuel mixture in the course of the 21-day test. Nitrile, HNBR, and fluorosilicone rubbers have such high permeability to M15 fuel that they would not be satisfactory as thin barrier layers in fuel hose.

282 Table 12.1 Permeability of M15 Fuel in Elastomers and Thermoplastics[1]

FLUOROELASTOMERS HANDBOOK

tape over the fluoroelastomer veneer previously extruded on a mandrel) to give very low Permeability Material (g·mm/m2·day) permeability to fuels. Additional layers of the hose may inElastomers: clude a tie layer, braided reinNBR 1600 forcement, and an outer layer. HNBR 1100 The outer elastomer layers may be chlorosulfonated polyFVMQ 640 ethylene, acrylate, or nitrile FKM-A 35 rubber, and a preferred reinFKM-B 12 forcing fiber is polyaramid. Volume swell of various FKM-GF 3 elastomers to Fuel C and sevThermoplastics: eral mixtures with oxygenNylon 12 85 containing additives is shown THV500 0.5 in Table 12.2.[2] [5] [6] The elastomers tested are ETFE 0.2 the same as those in Table FEP 0.03 12.1, except for epichlorohydrin rubber (ECO). The highfluorine elastomer listed in Table 12.2 is bisphenol-cured FKM-F rather than Fluoroelastomers have much lower permeability to peroxide-cured FKM-GF. For the methanol-containthis methanol-containing fuel, but show considerable ing fuel, it should be noted that permeability (see variation with fluorine (VDF) content. Nylon 12, with Table 12.1) correlates well with volume swell (see its polar amide linkages, has relatively high permeTable 12.2), as expected from Eq. 12.2. Generally, ability to methanol-containing fuel. The crystalline if an elastomer compound swells more than about fluoroplastics have very low permeability. 20% in a fuel mixture, it would not be adequate as a It is instructive to consider what these permethin veneer barrier layer in a fuel hose. However, ability values mean for estimation of M15 fuel loss such elastomers may be useful in o-ring or gasket from a section of fuel hose, say one foot (0.3 m) seals with thicker cross sections. long with 6 mm inside diameter (area for permeBisphenol-curable fluoroelastomer precomation A = 5.65 × 10-3 m2) with a veneer barrier layer pounds (and gums designated with *) recommended thickness of 0.5 mm. For HNBR, fuel loss would be for fuel hose extrusion applications are listed in Tasome 12 g/day, well above the 2004 CARB limit of ble 12.3. Fluoroelastomers with 66% fluorine are 0.5 g/day for the entire vehicle. Even a thickness of VDF/HFP dipolymers; others are VDF/HFP/TFE 5 mm would not provide an adequate barrier. For a terpolymers. The precompounds contain Bisphenol 0.5-mm veneer of FKM-B in this section of fuel hose, AF, accelerator, and optional process aids. The polythe loss would be about 0.14 g/day of M15, somemers have low to medium viscosities. what borderline for this fuel. FKM-A is not suffiSeveral of these products are also recommendciently resistant to this fuel, but a thin veneer of FKMed for molding applications, and have been described GF or other high-fluorine elastomer would be in Ch. 11. Curing characteristics and vulcanizate satisfactory. With their very low permeability to oxyproperties of the high-fluorine types, Viton® F605C genated fuels, fluoroplastics such as THV500 are and Tecnoflon ® FOR 4391, are described in finding use in fuel-line hose. The excellent barrier Table 11.13. Characteristics of dipolymer gum, properties of high-fluorine FKM elastomers and fluViton A200, and dipolymer precompound, Tecnooroplastics are combined in a novel DuPont™ Dow [4] flon FOR 5351/U, are described in the Rubber F200 fuel hose construction. This hose has an inFormulary charts in Section 11.5. Properties of ner veneer of fluoroelastomer, then a thin layer of all of the Dyneon precompounds in Table 12.3 are fluoroplastic (usually installed by wrapping thin FEP

12 COMPOUNDS FOR AUTO FUEL SYSTEMS

283

described in the following charts from The Rubber Formulary.[11] (Table 12.4) Compounds of the fluoroelastomer gum types, dipolymer Tecnoflon N 535,[12] and terpolymer, Viton B-202,[13] are described in Table 12.5. Bisphenol curing of fluoroelastomer precompounds recommended for extrusion is described in Table 12.6. Cured properties of actual fuel hose veneer would not necessarily match those of the stocks listed in these tables, which were press cured and post cured. In practice, the fluoroelastomer veneer stock

is extruded on a mandrel along with other layers (see Fig. 12.2), then cured in an autoclave for 30-60 minutes at 150ºC–160ºC (similar to curing of Dai-el® G-558 in Table 12.6). Normally, long high-temperature oven post curing would not be carried out on this composite, which contains less heat-resistant elastomer (such as nitrile) in the cover stock. Bisphenol-containing precompounds designed especially for fuel hose applications contain accelerator packages designed for attaining good properties after autoclave curing.

Table12.2 Swell of Elastomers in Fuel Mixtures[2][5][6]

Mixtures with Fuel C % Volume Swell (168 hours/23°C) Elastomer

Fuel C

MTBE 10%

Methanol

Ethanol 10%

10%

15%

NBR

7

49

69

61

ECO

6

32

45

54

24

26

28

26

FKM-A (66% F)

6

8

13

17

31

FKM-B (69% F)

5

6

8

14

16

FKM-F (70% F)

3

3

4

5

7

FVMQ

Table12.3 Fluoroelastomers for Extrusion Applications

Trade Name

Composition, %Fluorine 66 A201C

Viton

[7]

A331C A200*

Dai-el[8]

Dyneon

G-755 FC 2120

[9]

FC 2182

69 B201C B202*

70 – 71 F605C

G-555 G-558 FE 5730 FT 2320

FE 5830

FX 11818

FOR 5351/U Tecnoflon

[10]

* designates a gum

FOR 531 N 535*

FOR 5381

FOR 4391

284

FLUOROELASTOMERS HANDBOOK

Table12.4 Hose/Extrusion Applications[11]

Formulation 1

2

3

4

5

6

Recipe Fluorel™ FE-5730Q*

100

Fluorel™ FE-5830Q*

100

Fluorel™ FC-2120*

100

Fluorel™ FC-2182*

100

Fluorel™ FT-2320*

100

Fluorel™ FX-11818*

100

MT Black (N990)

30

MgO

3

Ca(OH)2

6

Physical Properties (press cure 10 min @ 177°C, post cure 24 hr @ 260°C) %F

69.2

70.5

65.9

65.9

69.0

68.6

S.G.

1.86

1.90

1.80

1.80

1.86

1.80

Mooney Visc. (1+10) @ 121°C

32

33

23

30

23

28

TR 10 (°C)

-12

-7

-18

-18

-12

-14

Tensile (psi)

1460

1600

2140

2200

2000

1800

Elongation (%)

330

250

200

265

230

290

M100 (psi)

375

640

850

550

750

490

Durometer, Shore A (pts)

71

80

75

70

79

74

Compression Set (ASTM D395, Method B, 70 hrs. @ 200°C)

45

44

16

22

39

34

Rheological Properties (Monsanto MDR 2000™, 100 cpm, 0.5° arc, 6 min) 177°C (350°F) ML (in-lbs)

1.1

1.0

0.9

1.2

1.4

1.0

ts2 (min)

1.3

2.0

1.3

0.8

1.3

1.2

t´50 (min)

1.4

2.3

1.6

0.9

1.8

1.5

t´90 (min)

1.9

3.3

2.4

1.5

3.0

2.0

MH (in-lbs)

9.8

15.4

20.0

13.4

22.5

13.7

200°C (392°F) ML (in-lbs)

0.7

ts2 (min)

0.6

t´50 (min)

0.7

t´90 (min)

0.8

MH (in-lbs)

11.5

*Incorporated cure polymer

12 COMPOUNDS FOR AUTO FUEL SYSTEMS

285

Table12.5 Curing of Fluoroelastomer Gums Used for Extrusion

Trade Name and Type

Composition

Tecnoflon[12] N 535

Viton[13] B-202

Dipolymer

Terpolymer

% Fluorine

66

69

ML-10 (121°C)

27

20

30

30

Ca(OH)2

6

6

MgO (High Activity)

3

3

FOR M1 (50% BpAF)

4.0

FOR M2 (30% Accelerator)

1.5

Recipe, phr MT Black (N990)

Curative 50 (80/20 BpAF/Accel.)

2.5

Curative 20 (33% Accelerator)

0.5

Stock Properties Viscosity, ML-10 (121°C)

50

54

ODR at 177°C, 3° Arc ML, dN·m

9

6.8

MH, dN·m

119

104

ts2, minutes

2.3

2.4

tc90, minutes

3.7

4.1

Press cure, 10 minutes at

170ºC

177°C

Post cure, 24 hours at

250ºC

232°C

M100, MPa

6.9

5.1

TB, MPa

17

13.2

EB, %

180

240

Hardness, Shore A

76

78

10

34

Vulcanizate Properties - Original

Compression Set, %, Disks 70 hours at 200ºC Fluid Resistance, Volume Swell, % Fuel C, 70 hours at 23°C Methanol, 70 hours at 23°C

3 17

286

FLUOROELASTOMERS HANDBOOK

Table12.6 Fluoroelastomer Precompounds for Extrusion

Trade Name and Type Tecnoflon FOR 531[14]

Tecnoflon FOR 5381[15]

Viton B-201C[16]

Dai-el G-558[17]

Dipolymer

Terpolymer

Terpolymer

Terpolymer

% Fluorine

66

69

69

69

ML-10 (121°C)

46

21

20

45

30

30

30

Composition

Recipe, phr MT Black (N990) SRF Black (N770)

15

Ca(OH)2

6

6

6

6

MgO (High Activity)

3

3

3

3

84

54

36

34

ML, dN·m

21

7

11

MH, dN·m

107

94

101

ts2, minutes

1.7

2.3

3.8

tc90, minutes

3.8

3.4

5.6

Press cure, min/°C

10/170

10/177

10/177

45/160

Post cure, hours/°C

24/250

24/250

24/232

24/230

M100, MPa

5.0

5.8

6.4

2.7

TB, MPa

14.8

12.7

11.6

12.5

EB, %

260

203

189

300

Hardness, Shore A

74

80

79

68

Stock Properties Viscosity, ML-10 (121°C) ODR at 177°C, 3° Arc

Vulcanizate Properties – Original

Vulcanizate Properties – Heat Aged After 70 hours at:

250ºC

TB Change, %

-15

EB Change, % Hardness Change, points

250ºC

232ºC

230ºC

-10

-9

+2

-8

+6

-11

+1

-1

+1

+2

0

24

28

Compression Set, % O-rings, 70 h/200°C Disks, 70 h/200°C

14 22

12 COMPOUNDS FOR AUTO FUEL SYSTEMS Stocks of fluoroelastomers used for fuel hose veneer must have excellent extrusion characteristics. The veneer is extruded through an annulus at high shear rate, and must be laid down on the mandrel as a uniform layer that can be further stretched to form the final hole-free thin veneer. Fluoroelastomers used have low viscosity, typically ML-10 (121°C) = 20–35. Most of the polymers initially developed for this application have relatively narrow molecular weight distribution, with Mw/Mn = 2–3. Recently, bimodal polymers have been developed that contain relatively large fractions with molecular weight below the critical chain length for entanglement. These serve as plasticizers to facilitate highshear extrusion. A possible weakness of such products is that many of the very short chains are not tied into the cured network, and may be subject to extraction by some fluid mixtures. Extraction is less likely if the polymer fluorine content is high. Choice of fluoroelastomer composition for fuelhose veneer largely depends on what fuels are used, and on fuel emission limits for the region. All VDF/ HFP copolymer and VDF/HFP/TFE terpolymer compositions are satisfactory for hydrocarbon fuel mixtures. Dipolymers are fairly resistant to fuels containing up to 10% MTBE or ethanol (E10), but

287 terpolymers with higher fluorine content may be necessary to meet very stringent U.S. requirements. Fuels containing relatively high levels of methanol, such as M15, generally require use of terpolymers with 69%–71% fluorine content to keep permeation losses within allowable limits. Current requirements vary with region, but the trend is toward more stringent emissions limits that will require high-fluorine polymers in barrier layers.

12.3 Fuel Tank Components Many fluoroelastomer components are used in modern automobile fuel tanks; some of these are shown in Fig. 12.4.[2] Included are o-rings and other seals, diaphragms, vibration isolators, couplings, and hose. Fluoroelastomer tubing and hose inside the tank connect vapor and liquid lines to the fuel sender module. The major requirement for in-tank elastomers is resistance to swell and chemical attack by the fuel. Fluoroelastomer parts must remain functional for the life of the vehicle. Bisphenol-curable dipolymer (66% fluorine) or terpolymer (68%–69% fluorine) compounds are recommended[2] for quick-

Figure 12.4 Fuel tank cut-away.[2] Description of applications of Viton®. (1) Quick connect coupling containing oring seal. (2) Rollover valve seal. (3) Quick connect o-ring. (4) On-board-diagnostics (OBD II) pressure sensor diaphragm. (5) Fuel pump o-rings. (6) Fuel sender vibration isolators. (7) Sender unit seal.

288 connect seals and fuel pump seals, whereas in-tank tubing and hose may require terpolymer with 69%– 71% fluorine content. Seals require good compression set resistance, so the compounds listed in Ch. 11 for o-ring applications would be appropriate (see Tables 11.2 and 11.10). Filler neck hose, shown in Fig. 12.5,[2] must have low permeability to fuel liquid and vapor to minimize emissions. The hose must also be flexible and tough enough to absorb shock and resist rupture in case of a vehicle accident. A construction often specified[2] is a molded part consisting of an inner layer of fluoroelastomer and a covering of nitrile rubber. Bisphenol-curable terpolymer (69%–71% fluorine) is a suitable inner layer for filler neck hose, having low permeability and good adhesion to the cover stock.

FLUOROELASTOMERS HANDBOOK

A cutaway view of a fuel injector with o-ring seals is shown in Fig. 12.6.[2] In common with other fuel system seals, fuel injector o-rings must be resistant to compression set for very long periods. In addition, fuel injector o-rings are subject to excursions to very high temperatures (125ºC–150ºC) that occur in the engine compartment. Many seal specifications include limits on short-term compression set (e.g., 70 hours at 150ºC) which can be met by several families of elastomers (nitrile, HNBR, acrylate, fluorosilicone, and fluoroelastomers). Such tests may not be adequate to insure seal durability in very long-term service involving many hours at high temperatures.[1] When compression set or retained sealing force of seals is measured over periods of 1,000 hours or more at 150ºC, fluoroelastomers are found

to retain sealing functionality long after failure of other elastomers, as shown in Fig. 12.7.[2] Fuel becomes “sour” when exposure to oxygen leads to formation of hydroperoxides which, in the presence of trace amounts of metal ions such as copper ions, form free radicals. Attack of free radicals on rubber parts may cause reversion (network breakdown), with failure by softening, or may cause further cross linking, with failure by embrittlement and cracking of parts.[2] A long-term study[1] was carried out to determine the effect of sour fuel on orings of various elastomer families. An artificial sour fuel with peroxide number 90 was made up of Fuel C containing t-butyl hydroperoxide with a trace amount of copper ion according to a Ford specification. O-rings mounted in Jamak stress relaxation jigs were exposed to sour fuel at 60°C for up to nine weeks, with retained sealing force measured periodically in a Shawbury Wallace load stand; fuel was changed weekly. In these tests, fluoroelastomer orings retained 30% (bisphenol-cured VDF/HFP/TFE terpolymer, 70% fluorine) to 55% (peroxide-cured VDF/PMVE/TFE tetrapolymer, 65% fluorine) of their original sealing force after nine weeks’ exposure. HNBR o-rings lost all sealing force after eight weeks, while fluorosilicone (FVMQ) o-rings retained only 20% of their original sealing force. In other tests of exposure to fuel with slightly higher peroxide number,[2] ECO failed by reversion and HNBR embrittled after two to three weeks, while VDF/HFP/ TFE elastomers of various compositions cured with either bisphenol or peroxide were little affected. While these tests may not closely simulate actual service in automobiles, the results indicate that fluoroelastomers are much more likely than other elastomers to give adequate fuel seal lifetime.

Figure 12.5 Filler neck hose.[2]

Figure 12.6 Fuel injector o-rings.[2]

12.4 Fuel Injector Seals

12 COMPOUNDS FOR AUTO FUEL SYSTEMS

289

inserted into one of three cells of the test block. Openings allow a choice of radial squeeze, corresponding to 10%, 20%, or 30% compression of the o-ring. A secondary back-up o-ring is installed above the leak port. Nitrogen pressure of 1.4 MPa (200 psi) is applied to the cell. The test block is placed in a lowtemperature cabinet and temperature is reduced until nitrogen leakage is detected. The temperature is noted at which leakage amounts to 5 or 10 standard cubic centimeters per minute (SCCM). Results for several fluoroelastomers are Figure 12.7 Retained sealing force of Viton® and other elastomers.[2] shown in Fig. 12.9[6] for dry o-rings and o-rings soaked in fuel for a week before testing. The polymers tested include a number of DuPont Viton compositions: From fuel swell measurements (Table 12.2), bisphenol-cured E-60C VDF/HFP dipolymer bisphenol-cure dipolymers and terpolymers or per(66% F); VDF/HFP/TFE terpolymers B70 (66% F), oxide-cured VDF/HFP/TFE fluoroelastomers have B600 (69% F), and 6191 (70% F); peroxide-cured sufficient resistance to hydrocarbon fuels and fuels VDF/PMVE/TFE fluoroelastomers GLT (65% F) containing up to 10% ethanol or MTBE to function and GFLT (67% F). Even with some plasticization as fuel injector seals, when formulated for good after fuel exposure, the HFP-containing fluoroelascompression set resistance. For fuels containing tomers generally do not seal against nitrogen preshigh levels of methanol (15% or more), VDF/HFP/ sure at -40ºC. The PMVE-containing elastomers proTFE fluoroelastomers containing 69%–71% fluorine vide better low-temperature sealing performance. are necessary to keep swell within reasonable limits. Such polymers and compounds are listed in Tables 11.2, 11.10, and 11.14. All of these elastomers are capable of long-term service at 200°C, well above temperatures encountered in automobile fuel service. However, low-temperature flexibility of HFP-containing fluoroelastomers is borderline for adequate seal performance in colder regions of the world. To attain good static sealing performance at temperatures of -40°C or below, peroxide-cured VDF/PMVE/TFE fluoroelastomers (see Table 11.16) may be necessary. PMVE-containing fluoroelastomers with 64%– 65% fluorine are satisfactory for hydrocarbon fuels and fuels containing up to 10% ethanol or MTBE, while polymers with 66%–67% fluorine may be necessary for fuels containing methanol at high levels. Low-temperature sealing performance of fluoroelastomer o-rings has been measured in a special testing apparatus, shown in Fig. 12.8.[6] Test o-rings, conforming in size to SAE Aerospace Standard 568214 (approximately 25 mm inside diameter by 3.54 mm cross section), are installed in a test plug that is

12.5 Development Trends During the 1990s, it appeared that a trend toward extensive use of flexible fuels containing high, variable levels of methanol would occur in the U.S. market. Such fuels would require the use of highfluorine elastomers for adequate sealing and emissions control. However, advances in refining technology allow tailpipe emissions to be minimized without high levels of oxygen-containing additives. Apparently, U.S. fuels will contain no more than about 10% ethanol or MTBE additives, and fuels used elsewhere will be hydrocarbons or ethanol-containing mixtures. Thus, current commercial fluoroelastomer compositions should be capable of meeting automotive fuel system requirements, even with continuing trends toward more stringent emissions control.

290

Figure 12.8 Low temperature o-ring tester.[6]

FLUOROELASTOMERS HANDBOOK

Figure 12.9 Low temperature sealing of fluoroelastomer o-rings.[6]

REFERENCES 1. R. D. Stevens, Permeation and Stress Relaxation Resistance of Elastomeric Fuel System Materials, SAE Technical Paper 2001-01-1127, SAE World Congress, Detroit, Michigan (March 5–8, 2001) 2. Viton® - Excelling in Modern Automotive Fuel Systems, DuPont Dow Technical Bulletin H-82107 (March 1999) 3. P. Campion, Rubber Chemistry and Technology, Rubber Reviews, 76:719–746 (July-August 2003) 4. R. D. Stevens, U.S. Patents 5,320,831, issued June 14, 1994, and 5,427,831 (June 27, 1995) 5. O. Franssen and N. Bothe, Viton® Engineering Properties – Presentation for End Users, Bad Homburg, Germany (January 1997) 6. R. D. Stevens, E. W. Thomas, J. H. Brown, and W. N. K. Revolta, Low Temperature Sealing Capabilities of Fluoroelastomers, SAE Technical Paper 900194, SAE International Congress and Exposition, Detroit, Michigan (February 26 – March 2, 1990) 7. Viton® Fluoroelastomer Selection Guide, DuPont Dow Technical Information (September 1998) 8. Dai-el™ Fluoroelastomer, Product Listing, www.daikin-america.com (June 2004) 9. Dyneon™ Fluoroelastomers, Product Listing, www.Dyneon.com (June 2004) 10. Tecnoflon Fluoroelastomer Products Index, www.solvaysolexis.com (November 2003) 11. P. A. Ciullo and N. Hewitt, The Rubber Formulary, PDL Handbook Series, The Formulary IX. Silicone & Fluoroelastomers, pp. 643–644, Noyes Publications/William Andrew Publishing, Norwich, New York (1999) 12. Tecnoflon N 535, Product Data Sheet, Solvay Solexis (December 2002) 13. Viton® B-202, DuPont Dow Technical Information (March 2004) 14. Tecnoflon FOR 531, Product Data Sheet, Solvay Solexis (December 2002) 15. Tecnoflon FOR 5381, Product Data Sheet, Solvay Solexis (March 2003) 16. Viton® B-201C, DuPont Product Information Bulletin VT-230.B-201C (November 1992) 17. Dai-el™ Fluoroelastomer G-558, Daikin Technical Information Bulletin ER-291 AK (November 2001)

13 Compounds for Auto Power Train Service 13.1 Introduction Several elastomer compositions are used in automotive power train service as seals for retention of oil and other lubricants in engines and transmissions. Recent trends have gone toward more aggressive lubricant compositions, higher temperatures, and longer seal lifetimes. Suppliers have responded by developing fluoroelastomers capable of meeting these severe service requirements.

13.2 Oil Seal Requirements Operating temperatures for engine oil seals (see Fig. 13.1[1] and cross section of lip seal with garter spring in Fig. 13.2[2]) vary widely, depending on engine design and location within the engine. Typically, the rear crankshaft seal is subjected to much higher temperatures than the front seal. Oil sump temperatures vary considerably, depending on provisions for oil cooling. This allows use of hydrogenated nitrile (HNBR), silicone, or acrylic elastomers for some seals in relatively low-temperature environments (120°C–140ºC). Standard fluoroelastomers (FKM), bisphenol-cured VDF/HFP/TFE terpolymers with 68%–69% fluorine content, perform well in oil service up to about 160ºC. More resistant fluoroelastomers are necessary for reliable long-term performance in more severe environments.

Figure 13.1 Shaft seals. (DuPont Dow Elastomers.)

As can be seen from the seal cross section shown in Fig. 13.2, shaft seals are complex shapes that require advanced mold design and molding techniques (see Sec. 6.3 for discussion of fluoroelastomer molding). Until recently, most shaft seals were made in the US by compression molding. Injection molding of shaft seals is prevalent in Europe, and is being used increasingly in the US. An advantage of compression molding is that preforms (usually rings cut from extruded tubing) are used that closely approximate the amount of stock required for the final parts, so compound waste is minimized. For injection molding, the amount of cured stock in the central sprue and runner (actually a thin sheet leading to the seal lip) is often large compared to the stock required for the final part, so the waste of high-cost fluoroelastomer may be high. Such waste is reduced in modern injection molding designs. The seal shown in Fig. 13.2 is a relatively simple design; most automotive seals are more complex. Dust lips are often used to keep outside contaminants away from the oil lip seals; such seals thus have undercuts that make demolding more difficult. Fluoroelastomer compounds used for such undercut shapes must have reasonably high elongation-atbreak at molding temperatures to avoid tearing the part during demolding. The metal insert is often Ushaped, and stock may be molded to form a thin layer over the outside of the insert. Since both compression and injection molding methods are used, suppliers of fluoroelastomers for shaft-seal applications often must provide different versions of the same

Figure 13.2 Oil retention seal. (CR Industries.)

292

FLUOROELASTOMERS HANDBOOK

polymer composition—medium to high viscosity for Modern engine oils, such as the current SG clascompression molding, and low to medium viscosity sification for gasoline engines, contain a large fracfor injection molding. Different precompounds may tion of additives, many of which are detrimental to be necessary to accommodate relatively long comfluoroelastomers. The primary functions of oil-addipression-molding times at low temperature and very tive packages are to protect metal parts, avoid deshort injection-molding times at high temperature. posits in the engine, minimize oil degradation, and Obtaining adequate adhesion of fluoroelastomer adjust fluid viscosity. Little attention has been paid compounds to metal inserts is a major consideration to avoiding damage to rubber seals. Instead, elasin fabrication of shaft seals. Adhesive systems tomer producers have been expected to provide new, worked out for bisphenol-cured VDF/HFP/TFE elashigher-performing products at no increased cost to tomers often do not perform adequately for peroxauto manufacturers. Among the additives with moiide-curable fluoroelastomers and more base-resiseties that may attack fluoroelastomers at high temtant polymers that contain little or no VDF. The trend perature are detergents (phenolates), dispersants toward use of more resistant fluoroelastomers in (succinimides, alkylphenol amines), and antioxidants shaft seals has necessitated considerable effort on (amines, sulfides, hindered phenols).[4] Many of these compounding and adhesive system development to components are multifunctional, containing phenol get adequate bonding of the new materials. Silaneor amine groups that can dehydrofluorinate and type primers are often used to coat metal inserts; crosslink VDF-containing fluoroelastomers, leading these contain residual active groups such as amine to loss of elongation and eventual embrittlement. functions that interact with the fluoroelastomer comHowever, the rate and extent of reactions with seals pound to attain good adhesion, especially for VDF/ are affected by many factors, including whether air HFP/TFE elastomers. Other adhesive systems, usis present in the system. When oil is exposed to air ing epoxy compounds or tie-coats, may be necesat high temperature, additives may undergo considsary for difficult bonding situations.[3] erable changes. For example, a significant fraction of amines may be oxidized to amides, which have Metal inserts must be carefully prepared in oplittle effect on fluoroelastomers.[5] erations involving cleaning and roughening surfaces (grit-blasting or phosphatizing), stamping out parts, Vulcanizates of several fluoroelastomers, listed application of primer (usually by dipping), and curin Table 13.1, were exposed to a standard 5W30 engine oil, ASTM Service Fluid 105, for up to six ing of the primer (often by baking for a short time at weeks at 150ºC.[5] The oil was changed weekly, but moderate temperature).[3] Primer curing minimizes the possibility of wiping primer off portions of the was not aerated. Retained elongation was measured insert by stock flow during molding. The treated metal after exposure for 1, 2, 3, and 6 weeks; data are inserts must be used within a relatively short time shown in Fig. 13.3. The results indicate that bisphenol(usually a day or less), so that functionality necescured FKM-A500 VDF/HFP dipolymer, FKM-B600 sary for bonding is not lost by reaction with moisture in the air. Freshness of the Table 13.1 Fluoroelastomers Used in Oil Aging[5] primer surface is particularly important for peroxide-cured and base-resistant fluoComposition Polymer Cure roelastomer compounds. Compound forDesignation % F System mulation should be adjusted to attain good Monomers adhesion. FKM-A500 66 VDF/HFP Bisphenol For bisphenol-cured VDF/HFP/TFE polymers, calcium hydroxide level should FKM-B600 69 VDF/HFP/TFE Bisphenol be low and magnesium oxide level should FKM-GFLT 67 VDF/PMVE/TFE Peroxide be high to promote adhesion to metal inFEPM-7456 58 TFE/P/VDF Peroxide serts. Thermal black or mineral fillers generally give good adhesion.[3] For most FEPM-7506 57 TFE/P/(VDF) Bisphenol adhesive systems, it is necessary to limit FEPM-7463 55 TFE/P Peroxide post-cure temperatures to about 200ºC.[3]

FEPM-ETP

67

E/TFE/PMVE

Peroxide

13 COMPOUNDS FOR AUTO POWER TRAIN SERVICE

Figure 13.3 Oil aging of fluoroelastomers.[5] Chart shows percent retained elongation. Conditions: aged at 150°C in Service Fluid 105 (oil changed every 168 hours).

VDF/HFP/TFE terpolymer, and peroxide-cured FEPM-7456 TFE/P/VDF terpolymer lost most of their original elongation over the course of the test exposure, indicating considerable additional crosslinking occurred by reaction with amine- and phenol-containing oil additives. The other fluoroelastomers showed better retention of elongation, being much less susceptible to additional crosslinking. Note that FEPM-7456 contains a high level of VDF (about 30%), while FEPM-7506 contains a relatively low VDF level (10%–15%) to serve as cure site for bisphenol curing. The other FEPM types contain no VDF. From this kind of standard immersion testing, one would expect that bisphenol-cured VDF/HFP/ TFE fluoroelastomers would not give good service life as oil seals. Similar tests with other elastomers, such as HNBR, silicone, and acrylic rubbers, show less loss of elongation. However, it is found that, in actual service, FKM shaft seals[6] have much longer service life than seals of the other elastomers. In a Japanese study of FKM lip seals, rear crankshaft seals from high-mileage automobiles (70,000–280,000 miles, 110,000–450,000 km) were collected and examined. No serious oil leakage was found when the seals were removed from the engines. Some deposits were found around the seal lip and on the garter

293 spring holding the lip against the shaft. No surface cracks were found on the seal lip, and only minor crazing on the crankcase side of the flexure portion of the seal in some samples. The seal compositions were not noted, but most were probably VDF/HFP/ TFE elastomers with 68%–69% fluorine content. J. G. Bauerle and D. W. Bruhnke[7] found that aeration reduces the effect of oil additives on fluoroelastomer properties. Some of their data is reproduced in Fig. 13.4,[5] showing the effect of aeration of an SF-grade 5W30 oil on the retention of elongation of a VDF/HFP dipolymer (FKM-E430), a VDF/HFP/TFE terpolymer (FKM-B600), and a VDF/PMVE/TFE fluoroelastomer (FKM-GFLT). The HFP-containing polymers show much better retention of properties with aeration. A more comprehensive study of aeration by B. N. Dinzburg[8] showed that even a minimal level of aeration of an aggressive European SF oil led to protection of a VDF/HFP/TFE compound, but to severe deterioration of an HNBR compound. He notes that aeration increases the severity of aging in oil for silicone and acrylic elastomers, while decreasing the severity for FKM elastomers. For more severe oil-seal service at temperatures of 160ºC or higher for extended periods, more resistant fluoroelastomer compositions are required for long service life. High-fluorine VDF/PMVE/TFE elastomers, along with TFE/olefin FEPM elastomers, are much less susceptible to attack by oil additives.

Figure 13.4 Effect of aeration on oil aging.[5] Chart shows percent retained elongation after aging for 28 days at 150°C in Mobil 276.

294

FLUOROELASTOMERS HANDBOOK maintain contact of the lip seal with the shaft (see Fig. 13.2). Thus, shaft-seal compounds are often designed to have higher elongation-at-break, and filler levels may be set to get desired modulus and swell. Oil seals made with peroxide-curable VDF/HFP/ TFE fluoroelastomers with iodine end groups providing most cure sites generally have longer functional service life than that for seals made with bisphenol-cured terpolymers having similar compositions. Apparently, formation of new crosslinks by reaction with oil additives is largely balanced by breakdown of original crosslinks at chain ends, so physical properties change slowly and sealing force is maintained for a longer time. These products include all the Dai-el and Tecnoflon peroxide-curable products listed, as well as the Viton® GBL-S and GF-S products.

TFE/P fluoroelastomers have the requisite chemical resistance, but have low fluorine content, leading to relatively high swell and to soft vulcanizates with lower wear resistance than desired.

13.3 Compounds for Oil Seals Fluoroelastomers recommended for use in oil seals are discussed in two categories that mostly reflect the severity of service for adequate performance. FKM elastomers contain major fractions of VDF units susceptible to attack by oil additives at high temperatures, so they are suited to seals operating at temperatures below 160ºC. FEPM elastomers are more resistant to chemical attack by additives, so they may give adequate long-term performance under more severe conditions.

13.3.1 FKM Elastomers A number of VDF/HFP/TFE fluoroelastomers usable in oil seals under moderate to severe conditions are listed in Table 13.2. Only highfluorine terpolymer compositions (68%–71% F) are included. The listing includes bisphenol precompounds, bisphenol-curable gums [G], and peroxide-curable gums [P]. Dipolymers and terpolymers with lower fluorine content are more susceptible to attack by oil additives, so shaft-seal lifetime would be too short for acceptability by most auto manufacturers. Low-fluorine polymers are usable for other engine seals such as valve stem seals. Several of the terpolymer precompounds listed in Table 13.2 contain additives to promote bonding to metal inserts. Most of the products have been described in Ch. 11; see Tables 11.9, 11.10, and 11.14 and accompanying text for curing characteristics. Sealing performance is not so dependent on compression set resistance, since a garter spring is used in shaft seals to

Table 13.2 VDF/HFP/TFE Fluoroelastomers for Shaft Seals

Composition Trade Name

68% F

69% F

70%–71% F

50% VDF

45% VDF

36%–30% VDF

VTR-9083 VTR-9084 Viton[9][10][11]

GBL-900 [P] GBL-200 [P] GBL-S [P]

B-435C B-641C

F-605C

B-651C

GF [P]

B [G]

GF-300 [P]

B-600 [G]

GF-S [P]

B-202 [G] FE 5840Q

Dyneon[12]

Dai-el

FLS 2650 [P]

[13]

G-551

G-621

G-952 [P]

G-901 [P] G-912 [P]

Tecnoflon

[14]

T 838K

FOR 5381

FOR 4391

P 457 [P]

FOR 9382

P 459 [P]

P 757 [P]

FOR 9381

P 959 [P]

13 COMPOUNDS FOR AUTO POWER TRAIN SERVICE Peroxide-curable VDF/PMVE/TFE fluoroelastomers are less susceptible than VDF/HFP/TFE polymers to crosslinking by oil additives. Thus, seals made with these PMVE-containing types do not fail by surface cracking and embrittlement, as occurs with most HFP-containing polymers. Instead, the seals gradually soften as slow network breakdown occurs, and long seal life is attained. The improved oil resistance of a representative VDF/PMVE/TFE polymer, Viton GFLT, is shown in Figs. 13.3 and 13.4, compared to HFP-containing FKM types. Available VDF/PMVE/TFE products are described in Ch. 11, Sec. 11.3, and listed in Table 11.16. Cure characteristics of polymers containing 64%–65% F and 67% F are shown in Tables 11.17 and 11.18. These are premium products that are somewhat higher in cost than other polymers used for shaft seals. It should be noted that, especially in Europe, most shaft seals for trucks are fabricated using fluoroplastics (TFE homopolymer and copolymers), technology that could be applied to automobile shaft seals. This sets an upper limit on costs for fluoroelastomer shaft seals, and may limit the use of high-cost PMVEcontaining elastomers for this application. However, fluoroplastic shaft seals tend to leak when the engine is shut down, an undesirable feature for autos, since homeowners don’t like to see oil spots on their driveways and garage floors.

13.3.2

FEPM Elastomers

With the trends toward higher engine temperatures, more aggressive oils, and extended warranties, automobile manufacturers have urged suppliers to develop elastomers with greater thermal and chemical resistance for engine seals. Inherently baseresistant E/TFE/PMVE fluoroelastomer (Viton Extreme ETP, described in Secs. 5.6 and 9.3) will withstand the environmental conditions, but is higher in cost than elastomers currently used in oil seals. Aflas™ TFE/P FEPM elastomer has adequate resistance to oil additives at high temperature, but swells and softens considerably in oil, so that longterm seal wear may be inadequate. Also the TFE/P dipolymer is very difficult to process and mold satisfactorily. The peroxide cure is slow, mold sticking and fouling occur in only a few heats, and adhesion to metal inserts of shaft seals is unsatisfactory.

295 Considerable effort has focused on terpolymers of TFE and propylene with vinylidene fluoride (VDF) or other monomers to get better curing and processing characteristics, lower swell in hydrocarbons, and adequate chemical resistance. Development of these polymers and cure systems for them has been described in Sec. 5.5, and fluid resistance of the products is described in Sec. 9.2. Oil resistance characteristics of these terpolymers are in accord with the results shown in Fig. 13.3, with high-VDF (30%) terpolymers such as FEPM-7456 similar to high-fluorine VDF/HFP/TFE and VDF/PMVE/TFE FKM fluoroelastomers; low-VDF (10%–15%) terpolymers, e.g., FEPM-7506, considerably better; and TFE/P/TFP terpolymer (no VDF) FEPM-7463 much better in property retention, comparable to ETP (see Table 13.1 for polymer descriptions). Commercial versions of TFE/P, TFE/P/VDF, and TFE/P/TFP polymers are listed in Table 13.3. Peroxide-curable polymers are indicated with [P]; other products are bisphenol-containing precompounds. Until the late 1990s, all commercial TFE/P dipolymers and TFE/P/VDF terpolymers were made by Asahi Glass Company under the Aflas trade name. These products have also been sold by Dyneon and DuPont Dow directly or used as base polymers for proprietary precompounds. Another polymer with enhanced base resistance, Tecnoflon BR 9151, is also listed, although this product is not classified as an FEPM type. This is a peroxide-curable polymer with four major monomers: Ethylene, VDF, HFP, and TFE. Ethylene is incorporated to reduce the number of base-susceptible HFP-VDF sequences, and a microemulsion polymerization process is used to make the relatively slow-propagating composition.[21] As noted, the TFE/P dipolymers are unlikely to find significant use in automotive shaft seals. TFE/ P/VDF polymers containing 30% or more VDF have base resistance only marginally better than high-fluorine VDF/HFP/TFE FKMs and no better than VDF/ PMVE/TFE polymers. Several fabricators of oil seals are carrying out development work with some of the products listed in Table 13.3, but full commercial use in automobiles has not yet occurred. Further polymer and compound development will probably be necessary to get products that are readily fabricated into long-lasting seals.

296

FLUOROELASTOMERS HANDBOOK

Table 13.3 FEPM Fluoroelastomers for Oil Seals

Composition Trade Name

Aflas[5][15] Viton[5][16][17] Dyneon[18][19] Tecnoflon

TFE/P

TFE/P/VDF

TFE/P/VDF

TFE/P/TFP

E/TFE/-

0% VDF

30%–35% VDF

10%–15% VDF

0% VDF

0%, 40% VDF

55%–56% F

57%–60% F

57%–60% F

59%–60% F

67%, 65% F

100S [P]

200 [P] SZ-301

150E, P [P]

MZ-201

VTR-7463[P]

IBR

TBR-501C

VTR-7456 [P]

VTR-7506

BRE 7231

BRE 7131

FX-11900

BRE 7132

[20]

13.4 Compounds for Transmission Seals Seals in automotive transmission systems (including differential, axle, and wheel-bearing seals) operate in severe environments.[5] Gear and wheelbearing lubricants and automatic transmission fluids contain additive packages similar to those in engine oils, but usually more concentrated, since these fluids are not changed at frequent intervals. These fluids are extremely aggressive toward VDF-containing fluoroelastomers, and there is no aeration to mitigate the effects of additives. Often a seal must retain lubricants on one side, while the other side is subjected to contaminants such as water, mud, and dust, which can cause problems with corrosion and abrasion. If temperatures are low enough, hydrocarbon elastomers such as hydrogenated nitrile (HNBR) or acrylate perform satisfactorily. However, temperatures of 150ºC may be attained for considerable periods when vehicles are driven long distances at high speeds. Because of this, automobile manufacturers would like to use more heat-resistant fluoroelastomers with adequate base resistance for long-term sealing performance. Of the fluoroelastomers listed in Table 13.3, TFE/P/VDF and TFE/P/TFP elastomers with

TBR-605CS

ETP-900 [P] ETP-600S [P]

BR 9151

0%–15% VDF, and ETP elastomers have adequate base resistance for use in transmission seals. As shown in Fig. 13.5, such polymers (exemplified as FEPM-7506, 7463, and ETP) are little affected by exposure to an EP Gear Lube for six weeks at 150ºC.[5] Differences between these polymers and high-VDF elastomers are more pronounced in more aggressive wheel-bearing lubricants. Since many of

Figure 13.5 Chart shows percent retained elongation after aging at 150°C in Shell 80W90 EP Gear Lube.[5]

13 COMPOUNDS FOR AUTO POWER TRAIN SERVICE

297

these polymers have been offered only recently, seal development is still under way, and little experience has been obtained on actual performance in automotive service. Some indication of the resistance of these FEPM elastomers to aggressive auto power

train lubricants and fluids is shown in Table 13.4. Fluids and exposure times vary, so aging results are not comparable for the different polymers. The information for Dyneon BRE 7100 is generic for this family of base-resistant low-VDF polymers.

Table 13.4 Fluid Resistance of FEPM Elastomers

Trade Name and Type [17]

Cure

Viton ETP-600S

Viton[16] TBR-605CS

Dyneon[22] BRE 7100

Peroxide

Bisphenol

Bisphenol

232ºC 9.1 19.0 191 80

200ºC 7.0 15.9 245 75

232ºC 5.3 13.2 213 71

-14 +38 0 ASTM 105

+20 -20 +1 ASTM 105

-36 -17 +2 Mobil 1

168 -8 +19 -1 2 Wheel-Bearing Lube Stuarco 7061 + 7098

1008 -6 +5 -2 6 Gear Oil 80W EP

168 -17 +1 -4 3 Daimler Chrysler Gear Oil MS 9763

168 -27 +19 -3 3

1008 -13 +3 -6 5

504 -16 +4 -2 6 Daimler Chrysler MS 9602

Physical Properties—Original Post cured at M100, MPa TB, MPa EB, % Hardness, Shore A Heat Aged, 168 hours at 250ºC TB, % change EB, % change Hardness change, points Aged in 5W-30 Oil, 150ºC Time, hours TB, % change EB, % change Hardness change, points Volume swell, % Aged in Lubricant, 150ºC Time, hours TB, % change EB, % change Hardness change, points Volume swell, %

Aged in Automatic Transmission Fluid, 150ºC Time, hours TB, % change EB, % change Hardness change, points Volume swell, %

504 -16 +2 -3 4

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FLUOROELASTOMERS HANDBOOK

REFERENCES 1. Viton® Stretches the Possibilities in Powertrain, DuPont Dow Elastomers Bulletin H-85509 (March 2000) 2. Shaft Seal Application Guide, CR Industries Bulletin 457090, ca. (1980) 3. Viton® Fluoroelastomer Processing Guide, DuPont Technical Information (July 2003) 4. P. F. Vartanian, Journal of Chemical Education, 68:1018 (December 1991) 5. T. M. Dobel and J. G. Bauerle, New FKM Developments for Automotive Powertrain Applications, SAE Technical Paper 2000-01-0745, SAE World Congress, Detroit, Michigan (March 6–9, 2000) 6. Y. Masuda, M. Nakada, Y. Esaki, T. Yoshihara, and D. Yarimizu, A Simulation Test Method for Deterioration of FKM Compounds Engine Crankshaft Seals, SAE Technical Paper 922373, International Fuels and Lubricants Meeting and Exposition, San Francisco, California (October 19–22, 1992) 7. J. G. Bauerle and D. W. Bruhnke, The Effects of Aeration of Test Fluids on the Retention of Physical Properties of Fluoroelastomer Vulcanizates, SAE Technical Paper 890362 (February 27 – March 3, 1989) 8. B. N. Dinzburg, Investigation of the Effect of Aeration on Automotive Oils and Rubber Components, ACS Rubber Division meeting, Nashville Tennessee (November 3–6, 1992) 9. Viton® Fluoroelastomer Selection Guide, DuPont Dow Technical Information (September 1998) 10. Viton® VTR-8650 – A New Peroxide Cured GBL Polymer, DuPont Dow Technical Information (December 2002) 11. Viton® VTR-8600 – A New Peroxide Cured GF Polymer, DuPont Dow Technical Information (December 2002) 12. Dyneon™ Fluoroelastomers, Product Listing, www.Dyneon.com (June 2004) 13. Dai-el™ Fluoroelastomer, Product Listing, www.daikin-america.com (June 2004) 14. Tecnoflon Fluoroelastomer Product Data Sheet, Recommended Grades Terpolymers, www.solvaysolexis.com (November 2003) 15. Aflas™ TFE Elastomers – Chemical Resistance, Dyneon Bulletin 98-0504-1151-5 (January 2001) 16. Viton® Extreme™ TBR-605C – A New, Bisphenol-Cure, Base-Resistant Polymer, DuPont Dow Technical Information (October 2003) 17. Viton® Extreme™ ETP-600S – A New, Peroxide-Cured ETP-S Polymer, DuPont Dow Technical Information (March 2004) 18. Dyneon™ Base Resistant Elastomers – 7000 Series, Dyneon Technical Information, www.Dyneon.com (January 2001) 19. P. A. Ciullo and N. Hewitt, The Rubber Formulary, PDL Handbook Series, The Formulary IX. Silicone & Fluoroelastomers, p. 668, Noyes Publications/William Andrew Publishing, Norwich, New York (1999) 20. Tecnoflon BR 9151, Product Data Sheet, www.solvaysolexis.com (December 13, 2002) 21. V. Arcella, M. Albano, E. Barchiesi, G. Brinati, and G. Chiodini, Development of New Nucleophile Resistant Vinylidene Fluoride Fluorocarbon Elastomers, ACS Rubber Division Paper 65, Louisville, Kentucky (May 19-22, 1992) 22. Dyneon™ Base Resistant Elastomers—Fluid and Heat Resistance Guide, www.Dyneon .com (March 2001)

14 Compounds for Power Plant Service 14.1 Introduction As in other industrial plants, fluoroelastomers are used in seals in power generation facilities where high temperatures are encountered and fluid leakage must be minimized. However, especially in coalfired power plants, a special application of fluoroelastomers is in expansion joints in the large ducts used to carry flue gases from furnaces to pollution control equipment and vent stacks.

14.2 Flue Duct Expansion Joints Elastomeric expansion joints are necessary to allow for differential expansion and contraction of large metal flue duct sections, while containing hot, corrosive flue gases in the system. In coal-burning plants, flue gases contain sulfuric and other acids, steam, carbon dioxide, air, and particulates (ash). The flue duct system carries this mixture to equipment for removing some of the pollutants, mainly ash and sulfur, then to vent stacks. The elastomeric expansion joints must withstand high temperatures and be resistant to steam and acid. High-fluorine (68%– 70%) VDF/HFP/TFE fluoroelastomers meet these service requirements. The low to medium viscosity polymers used are designed for the good calen-

dering characteristics necessary to form the large sheet structures. Calendering of fluoroelastomers is discussed in Sec. 6.5. The main market for fluoroelastomers in flue duct expansion joints has been in the U.S,, as part of required efforts to reduce power plant pollution. Initial U.S. installations required considerable fluoroelastomer, but long service life results in a minimal replacement market. As better pollution control is required for power plants in Europe and Asia, some demand may build up for fluoroelastomers in this application.

14.3 High-Fluorine Terpolymers Bisphenol-cured VDF/HFP/TFE fluoroelastomers containing 69% fluorine have been used successfully in flue duct expansion joints. Calendering compounds offered by DuPont Dow and Dyneon™ are described in the appended Tables 14.1 and 14.2 from The Rubber Formulary.[1] A number of VDF/HFP/TFE fluoroelastomers containing 68%–70% fluorine are recommended by suppliers for calendering, and should be usable in flue duct expansion joint service. Most are bisphenol-containing precompounds; bisphenol-curable gums [G] and peroxide-curable gum polymers [P] are also included in the listing in Table 14.3.

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FLUOROELASTOMERS HANDBOOK

Table 14.1 Calendering Compound (DuPont Dow)[1]

Recipe Viton B-600

96.3

Calcium Hydroxide

6

N990

30

Maglite D

3

Carnuba Wax

1

Viton Curative #20

2.5

Viton Curative #50

1.2 Total

140

Expected Physical Properties—Original Tensile Strength, psi

1835

Elongation, %

225

Hardness, Shore A

71

Compression Set, 70 hours @ 100°C, %

31

14 COMPOUNDS FOR POWER PLANT SERVICE

301

Table 14.2 Fabric Composite/Calendered Sheet Applications (Dyneon™)[1]

Formulation 1

2

Recipe Fluorel™ FC-2120

100

Fluorel FT-2350

100

MT Black (N990)

30

30

MgO

3

3

Ca(OH)2

6

6

Physical Properties (press cure 10 min @ 177°C, post cure 24 hr @ 260°C) %F

65.9

68.6

S.G.

1.80

1.80

Mooney Visc. (1+10) @ 121°C

23

56

TR 10 (°C)

-18

-14

Tensile (psi)

2140

2210

Elongation (%)

200

310

M100 (psi)

850

540

Durometer, Shore A (pts)

75

75

Compression Set (ASTM D395, Method B, 70 hr @ 200°C)

16

36

Rheological Properties (Monsanto MDR 2000™, 100 cpm, 0.5° arc, 6 min) 177°C (350°F) ML (in-lbs)

0.9

2.8

ts2 (min)

1.3

0.9

t´50 (min)

1.6

1.2

t´90 (min)

2.4

1.7

MH (in-lbs)

20.0

15.8

200°C (392°F) ML (in-lbs) ts2 (min) t´50 (min) t´90 (min) MH (in-lbs)

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FLUOROELASTOMERS HANDBOOK

Table 14.3 VDF/HFP/TFE Elastomers for Calendered Sheet

Composition Trade Name

68% Fluorine

69% Fluorine

70% Fluorine

B-201C B-435C

Viton

GBL-200 [P]

[2]

GBL-205LF [P]

B-601C

F-605C

B-641C

GF-300 [P]

B-651C

GF-205NP [P]

B-401 [G] B-600 [G] Dyneon[3]

FT 2350

FE 5832X FOR 4391

Tecnoflon

[4]

T 838K

FOR 5381

P 459 [P] P 959 [P]

REFERENCES 1. P. A. Ciullo and N. Hewitt, The Rubber Formulary, PDL Handbook Series, The Formulary IX. Silicone & Fluoroelastomers, pp. 662 and 667, Noyes Publications/William Andrew Publishing, Norwich, New York (1999) 2. Viton® Fluoroelastomer Selection Guide, DuPont Dow Technical Information (September 1998) 3. Dyneon™ Fluoroelastomers, Product Listing, www.Dyneon.com (June 2004) 4. Tecnoflon Fluoroelastomer Product Data Sheet, Recommended Grades Terpolymers, www.solvaysolexis.com (November 2003)

15 Other Fluoroelastomer Applications and Processing 15.1 Introduction Many fluoroelastomers end uses have not been covered in this book, but most of these are based on processing methods already described. Applications discussed below involve low volumes of fluoroelastomers, but some may become more important in the future.

15.2 Latex and Coatings Latex processing, including compounding and curing, is described in Sec. 6.6.1, using Tecnoflon TN Latex[1] as an example. This is a typical VDF/ HFP/TFE terpolymer latex, concentrated to about 70% solids by creaming after stabilizing the dispersion (20%–30% solids) from the polymerization reactor. The latex is compounded with a diamine for curing at low temperature (see Table 6.3). A similar latex has been developed by DuPont Dow Elastomers, but is offered only on a limited basis to chosen customers. Dyneon® Fluoroelastomer FX 10180 is a terpolymer latex for coating applications.[2] This latex is essentially a low solids (20%) reactor effluent dispersion that has been stabilized by soap addition and pH adjustment. Customers would usually cream such a latex to get sufficiently high solids for obtaining coatings of reasonable thickness.

Several low-viscosity fluoroelastomers are offered for solution coating applications. Customers dissolve such polymers in ketones or esters to form solutions with concentrations high enough to lay down coatings of acceptable thickness. Solution coating operations involve handling volatile, flammable solvents with attendant safety and environmental issues. Most of the polymers recommended for solution coatings are VDF/HFP dipolymers (66% fluorine); several are listed in Table 15.1. These fluoroelastomer gums may be cured with bisphenol or diamine systems; fillers and metal oxides may be dispersed and suspended in solutions before coating. Suitable solvents include low molecular weight esters, such as ethyl acetate, butyl acetate, or amyl acetate; and ketones, such as acetone, methyl ethyl ketone, or methyl isobutyl ketone.

15.3 Thermoplastic Processing Fluorinated thermoplastic elastomers (FTPEs) of the A-B-A block type have been described in Sec. 6.6.2. The main commercial product is offered by Daikin as Dai-el® Thermoplastic T-530,[8] which has central (B) VDF/HFP/TFE elastomer segments and outer (A) plastic segments of E/TFE/HFP terpolymer. Characteristics of this FTPE are described in Sec. 6.6.2 and Table 6.4. The major melting en-

Table 15.1 Low-viscosity Fluoroelastomers for Solution Coatings

Trade Name

Viton[3]

Composition VDF/HFP VDF/HFP/TFE 66% Fluorine 70% Fluorine Type [ML-10 (121ºC)] A-100 [12] A-200 [22]

Dyneon[4][5]

FC 2211 [20] FC 2230 [38]

Tecnoflon[6][7]

N 215 [10] N 535 [27]

FE 5832X [28]

304 dotherm is at about 220ºC, but softening occurs at lower temperatures, so that the practical upper use temperature is about 120ºC. Above this temperature, creep leads to poor dimensional stability, and loss of sealing force for parts used as seals. A higher melting, base resistant, developmental FTPE is also described in Sec. 6.6.2. This polymer can be cured by irradiation after molding to get useful properties at 150ºC or higher, as shown in Table 6.5. FTPEs may become more attractive to automotive seal suppliers, since scrap loss can be reduced greatly, compared to thermoset elastomers. Some improvement in high-temperature performance may be necessary, however. Dyneon offers a family of THV fluorothermoplastics,[9] terpolymers of TFE, HFP, and VDF, which are crystalline plastics rather than elastomers. As discussed in Sec. 2.2 and shown in Fig. 2.3, these compositions have high TFE content (45%–70%) and low HFP content (<15%). Melting ranges vary from about 120ºC to 185ºC,[10] depending on TFE content. Flexural modulus also increases with TFE content. These terpolymers are used in extruded tubing and hose, film and sheet, and molded seals.[9] These high-fluorine plastics are resistant to many fluids, and are partially replacing fluoroelastomers in automotive fuel hose. Dyneon® THV fluorothermoplastic terpolymers are further described in a previous volume in this Plastics Design Library series.[11]

15.4 Fluoroelastomer Caulks Low-viscosity fluoroelastomers such as those listed in Table 15.1 with ML-10 (121ºC) below 30 can be formulated as caulks for application by lowpressure extrusion. To get lower viscosity, very low-molecular weight VDF/HFP dipolymers (66% fluorine) are available for blending at levels up to about 20% in other fluoroelastomers. These dipolymers are pastes at room temperature and viscous liquids at elevated temperatures. Available products are Dai-el® G-101[12] and Dyneon FC 2210X.[13] Since these polymers have number-average molecular weights of only a few thousand, they serve as plasticizers to reduce stock viscosity, modulus, and hardness. However, at usual levels of curatives, most of these very short chains are not incorporated into

FLUOROELASTOMERS HANDBOOK cured networks, and are susceptible to extraction by polar components of fluids (e.g., methanol in fuels). Recently, DuPont Dow Elastomers has developed technology for cured-in-place gaskets of highperformance elastomers.[14] Cured-in-place part fabrication has mainly been the domain of two-part liquid systems, either silicone or polyurethane. The DuPont Dow Vertex™ seal technology utilizes robotic equipment similar to that used for hot melt adhesives to extrude a patented compound on a metal or plastic surface, then effects curing with ultraviolet light. The first compound offered commercially is based on ethylene acrylic elastomer, but fluoroelastomer compounds are under development.[15] Compounds are translucent solids that must be heated before dispensing as a low-viscosity melt. The compounds contain an incorporated cure system, with curing initiated by exposure to UV light after the material is dispensed into place. The technology, offered for licensing, is expected to be advantageous for automotive engine and transmission gaskets. Compared to standard elastomer molding processes, the cured-in-place technology results in less scrap and lower installation costs.

15.5 Processing Aids for Hydrocarbon Plastics Small amounts (50–1000 ppm) of fluoropolymer (elastomer or plastic) dispersed in hydrocarbon thermoplastics can greatly improve their extrusion characteristics, reducing melt fracture and die buildup. These improvements are especially important in film extrusion of high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) resins. To serve this market, DuPont Dow Elastomers offers Viton® FreeFlow™ additives, and Dyneon offers Dynamar™ Polymer Processing Additives (PPAs). These processing aids form a non-stick fluoropolymer coating on the inside of the die, reducing friction so that the resin flows freely and more rapidly through the die to produce an extrudate with smooth surfaces.[16] The die coating forms as the resin containing process aids is fed to the extruder, and removal of the coating by polymer flow is balanced by renewal from process aid dispersed in the continuing feed. Processing aid technology has evolved over the last twenty years, with original fluoroelastomer

15 OTHER FLUOROELASTOMER APPLICATIONS AND PROCESSING products replaced with synergistic blends and additives containing optimized polymers and interfacial agents.[17] Various additive formulations have been developed for different resin types and extrusion processes.[18] Additives are recommended for resins other than polyethylene, including polypropylene, polyvinyl chloride, nylon, acrylic, and polystyrene, mainly for higher throughput and elimination of die buildup. Extrusion processes for which additives are recommended include film, tubing, filament sheet, and wire and cable. Powdered additives may be added to thermoplastic resin powders being fed to an extruder,[19] or may be dispersed as a concentrate (2%–5%) in a resin before adding to the final thermoplastic.[20] A recent patent[21] assigned to DuPont Dow teaches the use of fluoropolymer processing aids with average fluoropolymer particle size greater than 2 microns in the melt as it reaches the die entrance. This is a departure from previous practice, which

305

emphasized dispersion of the fluoroelastomer to smaller particle sizes. In examples, additives containing fluoroelastomer particles of 4–7 microns eliminate melt fracture in shorter conditioning times and lower die pressure in LLDPE than additives with smaller particle size. Apparently, larger particles transfer fluoropolymer mass to the die surface more quickly. Polycaprolactone of molecular weight 2,000–4,000 is found to be better at maintaining the desired particle size than the poly(oxyalkalene) interfacial agents often used. A relatively high-viscosity VDF/HFP dipolymer with controlled rheology (probably Viton A-700) is particularly effective at low levels, since the polymer resists breakdown to very small sizes under shear in the extruder. A new family of process aids based on this technology has been introduced.[22] The new products show improved performance in difficult situations and have better thermal stability than other additives.

REFERENCES 1. Tecnoflon TN Latex, Solvay Solexis Product Data Sheet, www.solvaysolexis.com (December (2002) 2. Dyneon™ Fluoroelastomer FX 10180, Dyneon Technical Information, www.dyneon.com (January 2001) 3. Viton® A-100, DuPont Dow Elastomers Technical Information (February 2003) 4. Dyneon™ Fluoroelastomer FC 2211, Dyneon Technical Information, www.dyneon.com (January 2001) 5. Dyneon™ Fluoroelastomer FE 5832X, Dyneon Technical Information, www.dyneon.com (June 2001) 6. Tecnoflon N 215, Solvay Solexis Product Data Sheet, www.solvaysolexis.com (December 2002) 7. Tecnoflon N 535, Solvay Solexis Product Data Sheet, www.solvaysolexis.com (December 2002) 8. Dai-el T-530, Daikin Technical Information, www.daikin-america.com (2003) 9. Dyneon™ THV Fluorothermoplastics, Product Catalog, www.dyneon.com, (2004) 10. Dyneon™ Fluorothermoplastics, Product Information, Dyneon Technical Information, www.dyneon.com (December 2000) 11. S. Ebnesajjad, Fluoroplastics, Volume 2: Melt Processible Fluoropolymers, Sec. 6.7, Plastics Design Library, William Andrew, Inc., Norwich, New York (2003) 12. Dai-el G-101, Daikin Technical Information, www.daikin-america.com (2004) 13. Dyneon™ Fluoroelastomer FC 2210X, Dyneon Technical Information, www.dyneon.com (December 2000) 14. Simplify Seal Production, Improve Performance with Vertex™ Seal Technology, DuPont Dow Elastomers Technical Information (July 2003) 15. T. M. Dobel and C. Ruepping, New Cured-In-Place Gasket Technology Using UV-Cured High Performance Elastomers. SAE Technical Paper, Detroit, Michigan (March 2004) 16. Viton® FreeFlow™ Advantage: How It Works, www.dupont-dow.com (August 2004)

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17. Viton® FreeFlow™ Technical Info, www.dupont-dow.com (August 2004) 18. Dynamar™ Polymer Processing Additives: Selecting the Optimal PPA for Various Resin Types, www.dyneon.com (August 2004) 19. Dynamar™ Polymer Processing Additives: Direct Addition During Resin Manufacture, Dyneon Technical Information (December 2000) 20. Dynamar™ Polymer Processing Additives: Concentrate Preparation, Dyneon Technical Information, (December 2000) 21. G. R. Chapman, Jr., and S. R. Oriani, U.S. Patent 6,642,310, assigned to DuPont Dow Elastomers, LLC (November 4, 2003) 22. Viton® FreeFlow™ Z200, DuPont Dow Technical Information (July 2003)

16 Fluoroelastomer Safety and Disposal 16.1 Introduction Different safety issues predominate in the various stages of the fluoroelastomer life cycle. Production of fluoroelastomers involves handling of a number of hazardous raw materials under conditions that must be closely controlled. Processors must carry out compounding and curing operations involving additional components with reactions at high temperatures that may generate hazardous by-products. Fabricated fluoroelastomer products are often used in severe environments where failures may have dangerous consequences. Disposal of fluoroelastomer products at the end of useful service life may be complicated by possible presence of contaminants and hazardous components.

16.2 Safety in Production In production of fluoroelastomers, safe handling of monomers is a major concern, largely because of potential for explosion of various mixtures. Polymerization process safety has been discussed in some detail in Sec. 4.9, and hazards of various monomers are covered in Ch. 3. Explosion hazards are minimized by eliminating possible ignition sources (e.g., electrical arcs, trace amounts of oxygen, and hot spots in equipment). Consequences of a deflagration are lessened by putting limits on compositions of monomer mixtures, and on temperatures and pressures in the process, so that explosion containment or relief is possible without harm to personnel or serious damage to plant equipment. Most major monomers are not highly toxic, but minor components such as cure-site monomers, modifiers, surfactants, and initiators often require special handling procedures to protect personnel. Monitoring systems are often necessary to detect low levels of hazardous materials that may come from small leaks. Adequate ventilation should be provided to protect workers from exposure to airborne contaminants. Besides engineering controls, operating and maintenance procedures must be carefully set up and followed by trained personnel. Process changes must be carefully evaluated for potential hazards. If possible, new polymerization process conditions

should be investigated on a small scale by the research and development staff, especially if the new conditions are outside the range of variables previously used in the plant. Plant tests should be carefully supervised and documented, preferably with participation of technical staff involved in the development of the new product or process change. Processing of fluoroelastomers involves compounding, forming, and curing operations. Equipment used for mixing, extrusion, and molding of elastomer compounds requires adequately trained operators safely following procedures designed to produce high-quality finished parts. Some of the curing ingredients are quite reactive and may be toxic. All must be well dispersed in the elastomer matrix for good results, including avoiding hot spots from excessive local reactions. Care must be taken to insure addition of proper amounts of curatives according to well-designed recipes. Wrong ratios of some components may lead to runaway reactions or production of excessive amounts of toxic by-products. Adequate ventilation should be provided to protect operators from toxic fumes, especially where hot stock is present (e.g., around mills, at the discharge of internal mixers and extruders, and in the vicinity of openings of hot presses). Material Safety Data Sheets are available from suppliers of fluoroelastomer gums, precompounds, curatives, and processing aids; these cover potential hazards and handling precautions for particular compositions. Several general precautions for handling fluoroelastomers are listed by all suppliers: store and use fluoroelastomers only in well-ventilated areas; avoid eye contact; do not smoke in areas where fluoroelastomers are present; and after skin contact, wash with soap and water. Also note that potential hazards, including evolution of toxic vapors, may exist during compounding, processing, and curing of fluoroelastomers, especially at high temperatures.[1] More detailed handling precautions are provided in a DuPont Dow bulletin.[2] Measurements of volatile products evolved during curing of fluoroelastomers by bisphenol and amines have been reported.[3] For a bisphenol-cured polymer, Viton® E-60C, the weight loss during press cure at 193°C was about 0.3%, with about 1.5% additional weight loss after post curing 24 hours at 232°C in an air oven. Most of the

308 weight loss (about 95%) was water, with minor amounts of carbon dioxide and fragments from curatives. Very small amounts of hydrogen fluoride were detected, amounting to about 80 ppm based on fluoroelastomer compound. Volatiles generated from peroxide curing are discussed in Sec. 5.1.3, and data from a bromine-containing stock is shown in Table 5.3. Most of the volatiles are water and hydrocarbon fragments from peroxide decomposition, but small amounts of methyl bromide are evolved (methyl iodide would be present when the polymer contains iodine cure sites). Small amounts of hydrogen iodide or hydrogen bromide may be given off during peroxide curing of fluoroelastomers.[4] Finely divided metals should not be used in fluoroelastomer compounds, since stocks containing them may undergo vigorous exothermic decomposition at high temperature.[2] Aluminum and magnesium powder are particularly sensitive. Some metal oxides such as litharge, dispersed at high levels in fluoroelastomer, may undergo exothermic decomposition at about 200°C. However, litharge is no longer recommended for compounding because of toxicity problems. Fires have occurred in air ovens during fluoroelastomer post curing for various reasons.[5] Fluoroelastomer parts should not be cured in the same oven with other elastomers. Silicones are a particular problem, because of chemical interactions between silicone rubber and the small amounts of HF generated by fluoroelastomer compounds. Adequate fresh air should be supplied, to allow removal of volatiles from the mainly recirculating flow. Parts to be post cured should be placed evenly around the oven, and not piled too deeply, to allow adequate air flow around the parts. Small pieces of flash and accumulated residues of processing aids may also serve as ignition sources for oven fires. Combustion products from fluoroelastomer compounds burned in a deficiency of oxygen (as is likely

FLUOROELASTOMERS HANDBOOK in an oven or building fire, or from fluoroelastomer dust on a cigarette) have been determined.[2] Besides major amounts of water and carbon dioxide, combustion products include carbon monoxide, hydrogen fluoride, carbonyl fluoride, fluoroform, and traces of fluorocarbon monomers.

16.3 Safety in Applications Applications of fluoroelastomer parts often involve contact with hazardous fluids at elevated temperatures. Failure of parts such as seals may result in personal injury in some cases. Care should be taken by users of parts to assure that the proper fluoroelastomer composition is chosen for the application. This is not always easy to determine, since many parts’ suppliers may not disclose the type of fluoroelastomer used. Information in Chs. 7–9 may be helpful in choosing the proper fluoroelastomer for particular service conditions. More detailed information can be obtained from fluoroelastomer suppliers.

16.4 Disposal Disposal of fluoroelastomers can be carried out by recycling, incineration with energy recovery, or by burying in a landfill.[6] Recycling is generally possible with uncured stock. Incineration is preferable for most material, including parts contaminated by absorbed fluids. However, the incinerator must be capable of scrubbing out acidic combustion products. Fluoroelastomer compounds burned in excess oxygen give off water, carbon dioxide, and hydrogen fluoride as volatile products.[2] The landfill is an option for most solid fluoroelastomers and parts, if they are not contaminated by toxic fluids.

16 FLUOROELASTOMER SAFETY AND DISPOSAL

309

REFERENCES 1. Viton® Fluoroelastomer Selection Guide, DuPont Dow Elastomers Technical Information (September 1998) 2. Handling Precautions for Viton® and Related Chemicals, DuPont Dow bulletin VT-100.1 (originally issued November 1980) 3. L. F. Pelosi, A. L. Moran, A. E. Burroughs, and T. L. Pugh, The Volatile Products Evolved from Fluoroelastomer Compounds During Curing, Rubber Chemistry and Technology, 49, No. 2 (May-June 1976) 4. Viton® GFLT-S Fluoroelastomer (VIT128) Material Safety Data Sheet, DuPont Dow Elastomers LLC (October 2002) 5. Viton® Fluoroelastomer Processing Guide, DuPont Dow Elastomers Technical Information (July 2003) 6. Viton® A-401C Fluoroelastomer (VIT007A) Material Safety Data Sheet, DuPont Dow Elastomers LLC (June 1999)

Appendix: PDL Ratings PDL Resistance Ratings Several tables in this book include PDL Ratings (Tables 7.1, 8.1, and 9.1). The PDL Resistance Rating is determined using a weighted value scale developed by PDL and reviewed by experts. Each of the ratings is calculated from test results provided for a material after exposure to a specific environment. It gives a general indication of a material’s resistance to a specific environment. In addition, it allows the users to search for materials most likely to be resistant to a specific exposure medium. After assigning the weighted value to each field for which information is available, the PDL Resistance Rating is determined by adding together all weighted values and dividing this number by the number of values added together. All numbers to the right of the decimal are truncated to give the final

result. If the result is equal to 10, a resistance rating of 9 is assigned. Each reported field is given equal importance in assigning the resistance rating since, depending on the end use, different factors play a role in the suitability for use of material in a specific environment. Statistically, it is necessary to consider all available information in assigning the rating. Supplier resistance ratings are also figured into the calculation of the PDL Resistance Rating. Weighted values assigned depend on the scale used by the supplier. The table on the next page gives the values and guidelines used in assigning the PDL Resistance Rating. The guidelines—especially in the case of visual observations—are sometimes subject to an educated judgement. An effort is made to maintain consistency and accuracy.

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Table. PDL Resistance Rating Guidelines Mechanical*2 Property Retained

Weighted Value

Weight Change

Diameter Length Change

10

0–0.25

>0–0.1

0–0.25

0–2.5

≥97

9

>.25–0.5

>0.1–0.2

>.25–0.5

>2.5–5.0

94 to <97

>1 to ≤2

8

>0.5—0.75

>0.2–0.3

>0.5—0.75

>5.0–10.0

90 to <94

>2 to ≤5

7

>0.75–1.0

>0.3–0.4

>0.75–1.0

>10.0–20.0

85 to <90

Slightly discolored, slightly bleached

>5 to ≤10

6

>1.0–1.5

>0.4–0.5

>1.0–1.5

>20.0–30.0

80 to <85

Discolored yellows, slightly flexible

>10 to ≤30

75 to <80

Possible stress crack agent, flexible, possible oxidizing agent, slightly crazed

>30 to ≤120

70 to <75

Distorted, warped, softened, slight swelling, blistered, known stress crack agent

>120 to ≤240

60 to <70

Cracking, crazing, brittle, plasticizer oxidizer, softened swelling, surface hardness

>240 to ≤480

>480 to ≤960 >960

5

4

3

>1.5–2.0

>2.0–3.0

>3.0–4.0

>0.5–0.75

>0.75–1.0

>1.0–1.5

Thickness Change

>1.5–2.0

>2.0–3.0

>3.0–4.0

Volume*1 Change

>30.0–40.0

>40.0–50.0

>50.0–70.0

Visual*3 Observed Change No change

2

>4.0–6.0

>1.5–2.0

>4.0–6.0

>60.9–90.0

50 to <60

Severe distortion, oxidizer and plasticizer deteriorated

1

>6.0

>2.0

>6.0

>90.0

>0 to <50

decomposed

0

solvent dissolved, disintegrated

BTT*4 (min.) ≤1

Permeation Rate (µg/cm2/min) ≤0.9

Hardness Change (Units) 0–2 >2–4

>0.9–9

>4–6 >6–9

>9–90

>9–12

>12–15

>90–900

>15–18

>18–21

>900–9000

>21–25

>25 >9000

*1 All values are given as percent change from original. *2 Percent mechanical properties retained include tensile strength, elongation, modulus, flexural strength, and impact strength. If the % retention is greater than 100%, a value of 200 minus the %property retained is used in the calculation. *3 Due to the variety of information of this type reported, this table can be used only as a guideline. *4 Breakthrough time: time from initial chemical contact to detection.

Glossary A Abrasion Resistance - Wear rate or abrasion rate is an important property of materials during motion in contact with other materials. Abrasion or wear resistance is measured by a number of methods such as ASTM D3389, also known as the Taber Test. Accelerator - Ingredient of an elastomer compound which facilitates or speeds up crosslinking reactions. In bisphenol curing of fluoroelastomers, quaternary ammonium or phosphonium salts are used as accelerators. Acrylate Rubber - Specialty elastomer family based on polymers of methyl, ethyl, or other alkyl acrylate esters, CH2=CH–COOR. These elastomers have heat resistance better than all other elastomers except silicones and fluoroelastomers. Acrylate rubbers formulated for good heat and oil resistance have poor low-temperature flexibility and poor water resistance. A copolymer of ethylene and methyl acrylate (DuPont Vamac®) has better heat stability than polyacrylate rubber. Vamac vulcanizates are resistant to motor oils at temperatures up to 150ºC. Adhesion Promoter - A coating applied to a substrate prior to adhesive application, in order to improve adhesion of the material, such as plastic. Also called a primer. Adhesive - A material, usually polymeric, capable of forming permanent or temporary surface bonds with another material as-is or after processing such as curing. Used for bonding and joining. Some of the classes of adhesives include hot-melt, pressure-sensitive, contact, UV cured, emulsion, etc. Adhesive Bonding - A method of joining two plastics or other materials in which an adhesive is applied to the parts surfaces. Bonding occurs through mechanical or chemical interfacial forces between the adhesive and adherend and/ or by molecular interlocking. Surface preparation of the adherends and curing of the adhesive may be required. Adhesive Bond Strength - The strength of a bond formed by joining two materials using an

adhesive. Bond strength can be measured by a technique such as extensiometry. See also Adhesive Bonding. Adhesive Failure - Failure of an adhesive bond at the adhesive-adherend interface. An example is an adhesive failure that leaves adhesive all on one adherend, with none on the other adherend. Adhesive failure is less desirable than cohesive failure because it is indicative of a joint with lower adhesive strength. See also Cohesive Failure. Adhesive Joining - See Adhesive Bonding. Agglomerates - Clusters of small particles formed in various processes, including agglomerates formed from association of particles during polymerization, from coagulation as part of polymer isolation, or from lumping together of particulate ingredients of an elastomer compound. Amorphous Phase - See Amorphous Polymer and Semicrystalline Plastic. Amorphous Polymer - Amorphous polymers are polymers having noncrystalline or amorphous supramolecular structure or morphology. Amorphous polymers may have some molecular order, but usually are substantially less ordered than crystalline polymers. Amorphous thermoplastics are glassy at use temperatures; these often have mechanical properties inferior to those of crystalline thermoplastics. Amorphous polymers with glass transition temperatures below use temperatures are elastomeric when molecular weight is sufficiently high. Crosslinking of polymer chains is usually necessary to impart recovery from deformation of fabricated elastomeric parts. Annealing - A process in which a material, such as plastic, metal, or glass, is heated then cooled slowly. In plastics and metals, it is used to reduce stresses formed during fabrication. The plastic is heated to a temperature at which the molecules have enough mobility to allow them to reorient to a configuration with less residual stress. Semicrystalline polymers are heated to a temperature at which retarded crystallization or recrystallization can occur.

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Asbestos - Fillers are made from fibrous mineral silicates, mostly chrysotile. Used in thermosetting resins and laminates in fibrous form as reinforcements and in thermoplastics such as polyethylene in finer form as a filler. Asbestos fillers resist heat and chemicals while providing reinforcement, but pose health hazards and therefore their use has been declining. Attractive Intermolecular Forces - Also see Van der Waals Forces. Autopolymerization - Spontaneous polymerization of a monomer in the absence of an added initiator that usually occurs in monomer storage tanks and transport lines. Inhibitors can be added to prevent autopolymerization. For example, tetrafluoroethylene autopolymerization can be prevented by the addition of α-pinene or Terpene B. Autopolymerization Inhibitor - A variety of terpenes, such as α-pinene, Terpene B, and d-limonene are useful to inhibit the polymerization of tetrafluoroethylene or other monomers in an uncontrolled manner during storage and transportation. The inhibitor is removed prior to polymerization in the reactor.

B Ball Mill - The function of a ball mill is the reduction in size of solid ingredients of dispersion. This media mill is in the shape of a cylinder made of metal or ceramic. It contains a media usually in the form of pebbles made from glass, steel, or zirconium oxide. The ball mill is loaded with the liquid and solid ingredients. Banbury Mixer - An internal mixer used for efficient mixing of rubber compounds. The machine has non-intermeshing rotors with close clearances between rotors and walls of the mixing cavity, so that high shear forces are applied for dispersion of ingredients in the elastomer matrix. A number of sizes are available for mixing laboratory to production scale batches of compound. Bar - A metric unit of measurement of pressure equal to 1.0 × 106 dynes/cm2 or 1.0 × 105 Pascal, or equivalent in more common units to 0.1 MPa or 14.5 lb/in2. It has the dimension of a

unit of force per unit of area. Used to denote the pressure of gases, vapors, and liquids. Barrier Material - Materials such as plastic films, sheeting, wood laminates, particle board, paper, fabrics, etc., with low permeability to gases and vapors. Used in construction as water vapor insulation, food packaging, protective clothing, etc. Billet - Refers to a solid or hollow cylindrical object made from fluoropolymers; billets of fluoroelastomer compounds are often charged to ram extruders used for making preforms for compression molding of parts. Bisphenol AF - A fluorinated bisphenol, 4,4´(hexafluoroisopropylidene)diphenol, used for curing fluoroelastomers containing vinylidene fluoride or other sites susceptible to nucleophilic attack (also see Bisphenol Cure). Bisphenol Cure - Cure system used for most vinylidene fluoride/hexafluoropropylene/(tetrafluoroethylene) fluoroelastomers. This system gives fast cures to high state with excellent processing safety; vulcanizates have excellent compression set resistance and high temperature stability. Components of the cure system include a bisphenol crosslinker (usually Bisphenol AF), a quaternary ammonium or phosphonium salt as accelerator, calcium hydroxide and magnesium oxide. Steps in curing include dehydrofluorination of active sites to form double bonds in the polymer chains; nucleophilic addition of phenolate to the double bonds, with the two phenol groups of the bisphenol forming crosslinks between chains; and sequestering of HF by the inorganic bases. All the cure system components must be finely dispersed as solid particles at processing temperatures (about 120°C); little reaction occurs at processing temperatures. At usual molding temperatures (170°C–200°C), rapid cure occurs after a short delay allowing adequate mold flow. Although cure is essentially complete in the mold, parts are post cured in an air oven at 200°C–240°C to remove volatile materials and enhance interaction with fillers. Bisulfite Initiator - Bisulfite or sulfite salt is a component of a redox initiator system for free radical emulsion or dispersion polymerization; the other major component is usually persulfate.

GLOSSARY A small amount of an activator, usually a copper or iron salt, may be used to obtain practical initiation rates at low polymerization temperatures. Persulfate/sulfite redox systems were used in polymerization of the first fluoroelastomer products, but are little used for fluoroelastomers developed more recently. Blender - This is the name of a family of equipment used for blending combinations of solid and liquid ingredients. A specific variety is Vcone blenders which may be used for producing mixtures of particulate compounding ingredients and optional liquid ingredients. Some blenders have a cylindrical shape, with blending achieved by tumbling, rolling, or a slowly moving agitator with plow or ribbon impellers. The latter type may be used for blending of fluoroelastomer crumb formed in the process of isolation from aqueous dispersion. Braiding - The name of the process in which fluoropolymer tubes, wires and cables are reinforced. Strands of metal and plastic and other thin wire shape materials are formed into braids and wrapped around the fluoropolymer tube or wire to improve pressure rating and wear and puncture resistance. Branching - Formation of long-chain branches on polymer chains, usually by transfer reactions to form free radicals at sites along chains, followed by propagation by monomer addition at the reactive sites. Long-chain branching results in broadened molecular weight distribution, with increased polymer bulk viscosity and vulcanizate modulus. Excessive branching may lead to poor flow and processing characteristics of the elastomer compound. Branching level in a polymer can be estimated from calculations based on SELC and intrinsic viscosity measurements. See SELC, Solution Viscosity. Breaking Elongation - See Elongation. Bromotetrafluorobutene (BTFB) - A cure site monomer incorporated in some fluoroelastomers to allow free radical curing; BTFB is 4-bromo-3,3,4,4-tetrafluorobutene-1, CH2=CH–CF2–CF2Br. Burst Strength - The pressure at which a tube fails mechanically (i.e., breaks open) is called burst strength.

315 Bursting Strength - Bursting strength of a material, such as plastic film, is the minimum force per unit area or pressure required to produce rupture. The pressure is applied with a ram or a diaphragm at a controlled rate to a specified area of the material held rigidly and initially flat but free to bulge under the increasing pressure.

C C8 - An alternative name for perfluoroammonium octanoate. Calender - This is the equipment by which a lower thickness is obtained from a thicker bead of polymer. The equipment consists of a stack of two to four rolls with adjustable gaps. Roll speeds are the same, so that stock is not subjected to shear on passing through the nip between rolls. The thicker sheet is fed into the calender opening where it is squeezed by the force of the rolls into thinner sheet. Fabric may be fed to the calender along with elastomer compound to make coated or impregnated fabric sheet. Capture Velocity - The air velocity that generates sufficient air flow to remove contaminated air being given off from the source and force it to flow into an exhaust hood. Carbon Black - A black colloidal carbon filler made by partial combustion and/or thermal cracking of natural gas, oil, or other hydrocarbons. Depending on the starting material, carbon black can be called acetylene black, channel black, furnace black, or thermal black. For example, channel black is made by impinging gas flames against steel plates or channel irons, from which deposits are scraped at intervals. The properties and uses of carbon black types can also vary. Thus, furnace black comes in high abrasion, fast extrusion, high modulus, general purpose, and semireinforcing grades among others. Furnace blacks are commonly used as reinforcing fillers for hydrocarbon elastomers, but are less used for fluoroelastomers. Thermal blacks made by pyrolysis of hydrocarbons in the absence of air are usually used for fluoroelastomer compounds. Thermal black consists of relatively large spherical particles (about 100 to 500 nm diameter) with few oxygen-containing groups on surfaces. MT Black

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FLUOROELASTOMERS HANDBOOK

(N990) is a thermal black which can be used in fluoroelastomers at levels up to about 40 phr without imparting excessively high hardness and modulus to compounds. Carbon Filler - Carbon fillers are a family of fillers based on carbon in various forms, such as carbon black and graphite. It is used as a black pigment, to improve lubricity, and to increase electrical conductivity of plastics. Also called powdered carbon, carbon powder. Carbonyl Fluoride F

C

F

O

Carbon Powder - See Carbon Filler. Carboxylic Acid COO H O

Cast Film - Film produced by pouring or spreading resin dispersion, resin solution, or melt over a suitable temporary substrate, followed by curing via solvent evaporation or melt cooling, and removing the cured film from the substrate. Casting - Method to produce a cast film. See also Cast Film. Chain Transfer Agent - A modifier added to a free radical polymerization system to limit and control molecular weight. Chain transfer involves capping off a growing free radical chain, with transfer of the radical activity to the residue of the chain transfer agent so that a new growing radical chain is started. Chemical Mechanical Polishing or CMP - It is a process that uses an abrasive, corrosive slurry to physically grind flat the microscopic topographic features on a partly processed wafer (planarization) so that subsequent processes can begin from a flat surface. Chemical Resistance - Degradation of a material caused by chemical reaction. Chemical Vapor Deposition or CVD - It is a process for depositing thin films from a chemical reaction of a vapor or gas. Chlorotrifluoroethylene (CTFE) - CF2 = CFCl

Coagulation - This is an initial step in an isolation process for separating fluoroelastomers from aqueous dispersions produced by emulsion polymerization. The polymer dispersion is broken (destabilized) to form large crumb particles. Usually the fluoroelastomer dispersion is diluted to 20% solids or less before adding an inorganic salt (alkali, alkaline earth, or aluminum salt) to coagulate the polymer. Coalescence - This refers to the mechanism for melting and consolidation of small uncured elastomer particles into large particles, films, or other formed shapes. Cobalt 60 (Co60) - One of the unstable isotopes of Co used widely as a source of gamma radiation. Coefficient of Linear Thermal Expansion - The change in unit of length or volume that occurs due to a unit change in temperature. The expansion and contraction of a material with changes in temperature depend on its coefficient of linear thermal expansion, and movement of a part that is attached to another part with a lower CLTE value may be restricted. Cohesive Failure - Failure of an adhesive bond that occurs within the adhesive leaving adhesive present on both adherends. Optimum failure is 100% cohesive failure when both shear areas are completely covered. See also Adhesive Failure. Cold Flow - See Creep. Cold Plasma - Plasma is used for treating material surfaces. It is made of a stream of ions, free radicals, and other atomic particles produced by introducing a gas into a vacuum chamber, followed by radiofrequency or microwave excitation of the gas. The energy dissociates the gas into ions and other particles. Plasma treatment modifies surfaces to make them harder, rougher, more or less wettable, and more adherable. Compression Molding - Method of forming and curing elastomer parts. A compression mold consists of two heated platens with one or more mold cavities of the shape desired for the part. Elastomer compound, usually preformed in the amount required to fill a cavity, is loaded into cavities in the lower half of the mold. The upper mold section and platen is then lowered and

GLOSSARY

317

the mold closed by hydraulic pressure for the time required for the part to cure. The mold is then opened for removal of parts. Compressive Strain - The relative length deformation exhibited by a specimen subjected to a compressive force. See also Strain, Flexural Strain, Tensile Strain. Conditioning - Process of bringing the material or apparatus to a certain condition (e.g., moisture content or temperature) prior to further processing, treatment, etc. Also called conditioning cycle. Conduction - In heat transfer, migration of energy due to a temperature gradient. Heat energy is transferred by the movement of molecules at hotter or colder temperatures, with different degrees of thermal motion, into colder or hotter regions, respectively. Configuration - Configuration refers to compounds with the same chemical structure (formula and constitution) but which differ in the disposition of the atoms in space, also called stereoisomers, as shown below.

Cl

H C

trans

C

H

Cl

Cl

Cl C

cis

C

H

H

Contact Adhesive - An adhesive that will adhere to itself on contact. When applied to both adherends, it forms a bond after drying, without sustained pressure on the adherends. Composed of neoprene or, less commonly, nitrile elastomers. See also Pressure Sensitive Adhesive. Contact Angle - The angle that the droplet or edge of the liquid forms with the solid plane is called the contact angle. Continuous Polymerization - A polymerization process in which the reaction medium (water for an emulsion polymerization), monomers, initiator, modifier, and dispersant are fed continuously to the reactor, and the resulting polymer dispersion or solution along with unreacted monomer and other ingredients are continuously withdrawn. Ordinarily, the reactor is a wellstirred tank, and a constant volume is maintained in the reactor by allowing the vessel to fill completely, with effluent leaving the reactor through a valve set to maintain constant pressure in the reactor. In such a reactor, with temperature and pressure maintained constant and with constant feed rates of reactants, polymerization proceeds at steady state conditions so that polymer characteristics do not change with time. Convection - The mass movement of particles arising from the movement of a streaming fluid due to difference in a physical property such as density, temperature, etc. Mass movement due to a temperature difference results in heat transfer, as in the upward movement of a warm air current. Copolymer - See Copolymerization.

Conformation - Refers to the relative positions of atoms to each other in a chain. A good example is the relative positions of methyl and hydrogen groups bonded to carbons number 2 and 3in butane. One could envision a number of combinations for the positions of two methyl groups. The barrier to the rotation of the groups around the carbon-carbon bond is so low that the individual conformations can be isolated. CH3 H

C H

H C

CH3 H

Copolymerization - A polymerization where more than one monomer takes part in the reaction and form the polymer chain. Corona Discharge Treatment - In adhesive bonding, a surface preparation technique in which a high electric potential is discharged by ionizing the surrounding gas, usually air. The gas reacts with the plastic, roughening the surface to provide sites for mechanical interlocking and introducing reactive sites on the surface. Functional groups such as carbonyls, hydroxyls, hydroperoxides, aldehydes, ethers, esters, carboxylic acids, and unsaturated bonds

318 have been proposed as reactive sites. Commonly used for polyolefins, corona discharge increases wettability and surface reactivity. In processing plastics, treating the surface of an inert plastic such as polyolefin with corona discharge to increase its affinity to inks, adhesives, or coatings. Plastic films are passed over a grounded metal cylinder with a pointed highvoltage electrode above it to produce the discharge. The discharge oxidizes the surface, making it more receptive to finishing. Also called corona treatment. See also Plasma Arc Treatment. Corona Treatment - See Corona Discharge Treatment. Corrosion - It refers to chemical reaction of metal surfaces with oxygen, acids, and bases. The properties of corrosion products are vastly different from those of metals, thus causing difficulties for the operation of the equipment. Covalent Bond - A bond formed by the sharing of two or more electrons between two atoms. Covalent bonds can be single (two electrons shared), double (four shared electrons), or triple (six shared electrons). Cracking - Appearance of external and/or internal cracks in the material as a result of stress that exceeds the strength of the material. The stress can be external and/or internal and can be caused by a variety of adverse conditions: structural defects, impact, aging, corrosion, etc., or a combination thereof. Also called resistance to cracking, grazing, cracking resistance. Creep - Nonrecoverable deformation in a part subjected to a continuous load. Creep is dependent on temperature and the duration and amount of the load. Critical Cracking Thickness - The maximum thickness which can be coated in a single layer (pass) of fluoroelastomer latex without crack formation. The thickness is measured after film coalescence has been completed. Critical Micelle Concentration - Concentration at which molecules of surfactant aggregate to form ordered clusters with molecules oriented so that lipophilic ends are inside the cluster and hydrophilic ends are largely near the interface with the water phase. Micelles are

FLUOROELASTOMERS HANDBOOK effective in taking up organic liquids, and may serve as sites for polymerization with formation of stabilized particles in some emulsion polymerization systems. Critical Shear Rate - Fluoropolymers, and generally thermoplastic materials, must be processed below the velocity at which melt fracture occurs, referred to as the critical shear rate. Melt fracture in molten plastics takes place when the velocity of the resin in flow exceeds the critical velocity, the point where the melt strength of the polymer is surpassed by internal stresses. Critical velocity of most fluoropolymers is usually much lower than most thermoplastics. Crosslinking - Formation of covalent bonds between chain-like polymer molecules, usually by reaction with multifunctional low molecular weight compounds. As a result of crosslinking, polymers such as thermosetting resins may become hard and infusible, and elastomers can recover to original shapes after large deformations. Crosslinking may be induced by heat, radiation (UV, electron beam, gamma rays), oxidation, or a number of the chemicals reactions. Crosslinking can be achieved either between polymer molecules alone as in unsaturated polyesters or with the help of multifunctional crosslinking agents such as diamines that react with functional groups of the polymers. A number of crosslinking systems have been developed for fluoroelastomers to get thermal and chemical resistance approaching that of the polymer itself. The most used crosslinking systems for fluoroelastomers are based on nucleophilic addition of diamines or bisphenols to reactive sites on polymer chains, and on addition of multifunctional “radical traps” to free radical sites formed on polymer chains. Crystalline Form - See Crystalline Phase. Crystalline Melting Point - The temperature of melting of the crystalline phase of a crystalline polymer. It is higher than the temperature of melting of the surrounding amorphous phase. Crystalline Phase - This is an organized structural arrangement for polymer molecules. In this arrangement, polymer chains are aligned into a closely-packed ordered state called crystalline phase.

GLOSSARY

319

Crystalline Plastic - See Semicrystalline Plastic. Crystallization Temperature - Temperature (or range of temperatures) at which polymer chain segments crystallize. Chain segments which were randomly distributed in the molten state become aligned into a close-packed ordered arrangement during the crystallization process. Most curable elastomers are largely amorphous, and contain less than about 5% segments which can crystallize at relatively low temperatures. Thermoplastic elastomers may contain up to about 25% segments which crystallize at high temperatures. Crystallinity - Crystalline content of a polymer expressed in weight percent. See also Crystalline Phase. CTFE See Chlorotrifluoroethylene. Curing - Term commonly used to describe crosslinking of elastomers to form useful parts. Curing of fluoroelastomer compounds usually is done in two steps: press curing for a short time in a closed mold to carry out the main crosslinking reactions; and post curing for an extended time in an oven to complete crosslinking and to remove volatile additives and by-products in order to obtain better physical properties and environmental stability of the parts. Cure Site - A site in a polymer chain that can be activated to allow crosslink formation between chains after the compound has been formed into the shape desired for the molded part. Cure Site Monomer - A monomer with a reactive group, ordinarily incorporated in elastomer chains at low levels, capable of undergoing crosslinking reactions at curing temperatures. The reactive sites should not react to a significant extent during polymerization and processing of the elastomer prior to curing.

D Deflagration - A violent reaction whereby fluorocarbon monomers, especially mixtures containing tetrafluoroethylene, are degraded. Reaction products include carbon and tetrafluoromethane.

Deflection Temperature Under Load - See Heat Deflection Temperature. Deformation Under Load - See Creep. Degradation - Loss or undesirable change in plastic properties as a result of aging, chemical reactions, wear, use, exposure, etc. The properties include color, size, strength, etc. Dehalogenation - Loss of a halogen atom (such as fluorine and chlorine) from a molecule is called dehalogenation. For example, alkaline metals like sodium can abstract fluorine atoms from fluoropolymers upon contact. Dehydrochlorination - See Dehydrohalogenation. Dehydrofluorination - Removal of HF from reactive sites on fluoroelastomer chains, usually as the first step in bisphenol or diamine curing of vinylidene fluoride / hexafluoropropylene / (tetrafluoroethylene) elastomers. See Bisphenol Cure, Diamine Cure. Dehydrohalogenation Removal of a hydrohalogen such as hydrogen chloride or hydrogen fluoride from a molecule is called dehydrohalogenation. This reaction usually takes place at elevated temperatures or by assistance from a catalyst. Density - The mass of any substance (gas, liquid or solid) per unit volume at specified temperature and pressure. The density is called absolute when measured under standard conditions, (e.g., 760 mm Hg pressure and 0°C temperature). Note: for plastics, it is the weight in air per volume of the impermeable portion of the material measured at 23°C according to ASTM D792. Also called mass density, absolute gravity, absolute density. Diamine Cure - Cure system used for crosslinking early vinylidene fluoride/hexafluoropropylene/ (tetrafluoroethylene) elastomer products, now largely replaced with the bisphenol cure system. Components of the diamine cure system include a partially blocked diamine such as hexamethylene diamine carbamate and low-activity magnesium oxide with large particle size. The diamine acts to dehydrofluorinate reactive sites in polymer chains and then forms crosslinks by nucleophilic addition to the double

320 bonds formed. Magnesium oxide takes up the HF removed from the chains. Compared to the bisphenol system, the diamine cure system has poorer processing safety (premature curing, “scorch,” occurs in a few minutes at 120ºC), slower curing in the mold, and poorer compression set resistance. Vulcanizates of vinylidene fluoride/hexafluoropropylene/(tetrafluoroethylene) elastomers are susceptible to further crosslinking and embrittlement upon exposure at high temperatures to fluids containing moieties which form diamines (e.g., automobile shaft seals exposed to engine oils containing amine additives). Die Cone Angle - The angle that the wall of the convergent section of the die forms with the axis of the paste extruder barrel (parallel to extrusion direction). Die Land - The part of the die (orifice) that is downstream from the convergent section where both cross-sectional area and shape are constant. Dielectric - A material that conducts no current when it has a voltage across it; an insulator. Two dielectrics commonly used in semiconductor processing are silicon dioxide (SiO2) and silicon nitride (SiN). Dielectric Breakdown Strength or Voltage The voltage (minimum) required to break down through the thickness of a dielectric (insulation material)(i.e., create a puncture). ASTM D149 is used to measure dielectric breakdown strength of plastic insulation material. Dielectric Constant - The dielectric constant of an insulating material is the ratio of the capacitance of a capacitor insulated with that material to the capacitance of the same capacitor insulated with a vacuum. Dielectric Dissipation Factor - The ratio of the power dissipated in a dielectric to the product of the effective voltage and the current; or the cotangent of the dielectric phase angle; or the tangent of dielectric loss angle. Note: measured according to ASTM D150 for plastics. Also called tan delta, permittivity loss factor, dissipation factor, dielectric loss tangent. Dielectric Loss Tangent - See Dielectric Dissipation Factor.

FLUOROELASTOMERS HANDBOOK Differential Scanning Calorimetry - DSC is a technique in which the energy absorbed or produced is measured by monitoring the difference in energy input into the substance and a reference material as a function of temperature. Absorption of energy produces an endotherm; production of energy results in an exotherm. May be applied to processes involving an energy change, such as melting, crystallization, resin curing, and loss of solvents, or to processes involving a change in heat capacity, such as the glass transition. Diiodoperfluoroalkane Modifier - A chain transfer agent used in “living” free radical semibatch emulsion polymerization to produce fluoroelastomers with very narrow molecular weight distribution and with iodine on most chain ends. The elastomers can be crosslinked by a free radical system, usually a peroxide plus triallylisocyanurate crosslinking agent. Resulting vulcanizates have excellent compression set resistance. Dip Coating - This method is the most popular way to coat cloth and fibers with fluoroelastomer or polytetrafluoroethylene dispersion. Typically, the substrate is dipped in the dispersion and excess dispersion is removed by a device such as a doctor blade. The wet coated substrate is then further processed. Viscosity of the dispersion determines the initial thickness of the wet coating immediately after removal from the dip tank. Dispersing Agent - See Surfactant. Dispersion - A dispersion is often defined as a uniform mixture of solid particles and a liquid. It may contain other agents such as a surfactant or a resin soluble in the liquid. Many dispersions are stable enough so that little settling of solid particles occurs. Aqueous dispersions of fluoroelastomers are typically less stable, and the dense polymer particles settle in a relatively short time unless mild agitation is maintained. Dispersion Polymerization - A polymerization system characterized by formation of a dispersion of relatively large polymer particles in water. A water-soluble surfactant is typically used to stabilize the particles and minimize coagulation. Free radicals are formed from

GLOSSARY initiator dissolved in the aqueous phase, but polymerization of monomer occurs in (or on the surface of) the polymer particles. In polymerization of crystalline fluoroplastics, little monomer is present in particles. Monomer diffuses through the aqueous phase, and polymerization takes place at or near particle surfaces. Temperature and agitation control are easier in this mode than in suspension polymerization. Polytetrafluoroethylene fine powder and dispersion are produced by this technique. Many fluoroelastomer polymerizations are better characterized as dispersion polymerizations than as emulsion polymerizations, the term usually used. Since the monomers are soluble in fluoroelastomers, polymerization takes place in monomer-swollen particles. See Emulsion Polymerization. Dissipation Factor - See Dielectric Dissipation Factor. Dopants - An impurity added in a controlled amount to a material in order to modify some intrinsic characteristic, such as resistivity/conductivity or melting point. Doping - Adding a controlled amount of impurities to a material in order to modify some intrinsic characteristic ( i.e., resistivity/conductivity, melting point). DSC - See Differential Scanning Calorimetry. Durometer Hardness - Indentation hardness of a material as determined by either the depth of an indentation made with an indentor under specified load or the indentor load required to produce a specified indentation depth. The tool used to measure indentation hardness of polymeric materials is called a durometer (e.g., Shore-type durometer). Dyne - Solutions made from a mixture of two chemicals that produce liquids with surface tension in the range of 30–70 dynes/cm used to estimate surface energy of plastics treated to enhance adhesion bond strength. The test consists of placing droplets of the various “dyne” liquids on the treated surface and observing the spreading of the drops in two seconds. Successive liquids with different surface tensions allow narrowing of the surface tension range of the web.

321

E ECTFE - See Ethylene Chlorotrifluoroethylene Copolymer. Elasticity - Property whereby a solid material changes its shape and size under action of opposing forces, but recovers its original configuration when the forces are removed. Electro Chemical Plating - A deposition process in which metals are removed from a chemical solution and deposited on a charged surface. Electron Beam - See Electron Beam Radiation. Electron Beam Radiation - Ionizing radiation propagated by electrons that move forward in a narrow stream with approximately equal velocity. Also called electron beam. Electronegativity - Electronegativity is defined as the capability of an atom of attracting/pulling electrons towards itself in a chemical bond; fluorine (F) is the most electronegative element. This concept is somewhat imprecise and can only be understood by an in-depth study of the atomic structure of elements. Electrophilic Attack - Electrophilic attack refers to the reaction of an electron deficient group with an electron rich group. For example, reaction of ethylene (CH2=CH2) with hydrofluoric acid (HF) is an electrophilic attack in which H+ approaches the electro rich double bond, forming a carbocation followed by nucleophilic attack by H-, as shown below. CH2 =CH2 + H+ → CH2+—CH3 + F→ CH2F—CH3 Elongation - The increase in gauge length of a specimen in tension, measured at or after the fracture, depending on the viscoelastic properties of the material. Note: elongation is usually expressed as a percentage of the original gauge length. Also called ultimate elongation, tensile negation, breaking elongation. Elongation at Break - The increase in distance between two gauge marks, resulting from stressing the specimen in tension, at the exact point of break. Measurement taken at the exact point of break according to ASTM D638. Emulsion - Stable dispersion of very small droplets of an immiscible liquid in another liquid, for

322 example, an emulsion of an organic liquid monomer in water stabilized by a surfactant. The term emulsion is often applied to an aqueous dispersion of fluoroelastomer particles which may have limited stability. See Dispersion. Emulsion Polymerization - Term used for a polymerization system characterized by initiation in the aqueous phase and polymerization in monomer-swollen particles stabilized by surfactant (added or formed in situ by aqueous-phase oligomerization). Monomer may be present as a separate liquid or vapor phase. Ordinarily, no true emulsion exists, but the name persists. Fluoroelastomers are produced by this polymerization technique, which limits termination by mutual reaction of growing radical chains and thus allows attainment of high molecular weights, necessary for good mechanical properties. Also see Dispersion Polymerization. Encapsulation - This term means to enclose as in a capsule. Polytetrafluoroethylene or fluoroelastomer compounds can be used to encapsulate metal articles to impart chemical resistance to them. Examples include encapsulated metal gaskets and butterfly valve gates. The metal provides mechanical strength and resistance to creep. End Groups - The functional groups appear at the ends of polymer chains and, in effect, “end” the chain growth. Environmental Stress Cracking - Cracking or crazing that occurs in a thermoplastic material subjected to stress or strain in the presence of particular chemicals or weather conditions or as a result of aging. Also called ESC. Epi or Epitaxy - A process technology used in some semiconductor designs where a pure silicon crystalline structure is deposited or “grown” on a bare wafer, enabling a high-purity starting point for building the semiconductor device. Epichlorohydrin Rubber (ECO) - Rubber based on an ethylene/epichlorohydrin copolymer. Vulcanizates are resilient, have intermediate heat resistance, good low-temperature flexibility, and good oil resistance. A rubber based on epichlorohdrin homopolymer has poor low-temperature characteristics, but is less permeable to gases.

FLUOROELASTOMERS HANDBOOK Epichlorohydrin is:

O H2

CH CH2Cl

Epoxides - Organic compounds containing threemembered cyclic group(s) in which two carbon atoms are linked with an oxygen atom as in an ether. This group is called an epoxy group and is quite reactive, allowing the use of epoxides as intermediates in preparation of certain fluorocarbons and cellulose derivatives and as monomers in preparation of epoxy resins. Etch - A process for removing material in a specified area through a chemical reaction. Etching - In adhesive and solvent bonding, a process used to prepare plastic surfaces for bonding. Exposure of the plastic parts to a reactive chemical, such as chromic acid, or to an electrical discharge results in oxidation of the surface and an increase in surface roughness by removal of surface material. ETFE - See Ethylene Tetrafluoroethylene Copolymer. Ethane - An alkane (saturated aliphatic hydrocarbon) with two carbon atoms, CH3CH3. A colorless, odorless, flammable gas. Relatively inactive chemically. Obtained from natural gas. Used in petrochemical synthesis and as fuel. Ethylene - An alkene (unsaturated aliphatic hydrocarbon) with two carbon atoms, CH2=CH2. A colorless, highly flammable gas with a sweet odor. Autoignition point: 543°C. Derived by thermal cracking of hydrocarbon gases or from gas synthesis. Used as monomer in polymer synthesis, refrigerants, and anesthetics. Also called ethene. Ethylene Acrylic Rubber - See Acrylate Rubber. Ethylene Chlorotrifluoroethylene Copolymer Thermoplastic comprised of an alternating copolymer of ethylene and chlorotrifluoroethylene. It has good impact resistance and good abrasion resistance, chemical resistance, weatherability, and electrical properties. It can be molded, extruded, and powder coated with uses in tubing, cable and wire insulation, valves, pump parts, wraps, and tower packing and chemical equipment applications.

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323

Ethylene Polymers - Ethylene polymers include ethylene homopolymers and copolymers with other unsaturated monomers, most importantly olefins such as propylene and polar substances such as vinyl acetate. The properties and uses of ethylene polymers depend on the molecular structure and weight. Ethylene Tetrafluoroethylene Copolymer Thermoplastic comprised of an alternating copolymer of ethylene and tetrafluoroethylene. Has high impact resistance and good abrasion resistance, chemical resistance, weatherability, and electrical properties approaching those of fully fluorinated polymers. Retains mechanical properties from cryogenic temperatures to 356°F. Can be molded, extruded, and powdercoated. Used in tubing, cable and wire products, valves, pump parts, wraps, and tower packing in aerospace and chemical equipment applications. Also called ETFE. Extrusion - Process for converting an ingot or billet into lengths of uniform cross section by forcing material to flow plastically through a die orifice; a product form produced by this process. Many variations of this process are used widely in working metals and processing plastics and elastomers.

F Fab - A facility for manufacturing semiconductors. Fatigue - Process of progressive localized permanent structural change occurring in a material subjected to conditions that produce fluctuating stresses and strains at some point or points and that may culminate in cracks or complete fracture after a sufficient number of fluctuations, according to ASTM E1150. See also Flexural Fatigue, Tensile Fatigue. Fatigue Life - Number of loading-unloading cycles of a specified type of material that can endure before failing in a fatigue test. Fatigue Strength - The limiting value of the median fatigue strength as the number of loading cycles sustained before failure becomes very large. Fatigue strength, here, is the maximum stress that can be sustained without failure at this number of loading cycles.

FEP - See Fluorinated Ethylene Propylene Copolymer. FEPM - See Fluoroelastomer. FFKM - See Fluoroelastomer. FKM - See Fluoroelastomer. Fibrillation - This phenomenon occurs when polytetrafluoroethylene fine powder particles are subjected to shear usually at above its transition point (19°C). For example, when fine powder particles rub against each other, groups of polymer chains are pulled out of crystallites. These fibrils can connect polymer particles together. They have a width of less than 50 nm. Filament - A filament is a small individual strand that is melt-extruded during fiber spinning. Bundles of filaments are called fiber or yarn. Film - A product (e.g., plastic) that is extremely thin compared to its width and length. There are supported and unsupported films such as coatings and packagings, respectively. Flame Retardant - A substance that reduces the flammability of materials such as plastics or textiles in which it is incorporated. There are inorganic flame retardants such as antimony trioxide (Sb2O3) and organic flame retardants such as brominated polyols. The mechanisms of flame retardation vary depending on the nature of material and flame retardant. For example, some flame retardants yield a substantial volume of coke on burning, which prevents oxygen from reaching inside the material and blocks further combustion. Also called fireproofing agent. Flash - In molding thermoplastics and elastomers, surplus material attached to the molding along the parting line. Flash must usually be removed before parts are considered finished. Flash from cured elastomer compounds is usually scrap; little can be reprocessed and blended into subsequent production. Flex Life - Flex fatigue life is the total number of cycles that a specimen can be “flexed” in a prescribed manner before failure occurs. Failure is defined as physical breakdown of the specimen material. A number of methods such as MIT, Ross and De Mattia are used to measure flex life. See also Fatigue Life.

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Flexural Fatigue - Progressive localized permanent structural change occurring in a material subjected to cyclic flexural stress that may culminate in cracks or complete fracture after a sufficient number of cycles. Flexural Fatigue Strength - Maximum stress that can be sustained for a specified number of bending cycles without failure. Flexural Modulus of Elasticity - The ratio, within the elastic limit, of the applied stress on a test specimen in flexure to the corresponding strain in the outermost fibers of the specimen. Flexural Properties - Properties describing the reaction of physical systems to flexural stress and strain. Flexural Strain - The tensile elongation on the surface of a cross section opposite to that experiencing a locally impinging force in bending at any time of the test. See also Strain, Compressive Strain, and Tensile Strain. Flexural Strength - The maximum stress in the extreme fiber of a specimen loaded to failure in bending. Note: Flexural strength is calculated as a function of load, support span, and specimen geometry. Also called modulus of rupture, bending strength. Flexural Stress - The maximum fiber stress in a specimen at a given strain in a bending test. The maximum fiber stress is a function of load, support span, and specimen width and depth. It depends on the method of load application relative to the supports and on the specimen geometry. It has to be calculated. Note: Flexural stress is calculated as a function of load at a given strain or at failure, support span, and specimen geometry. Fluid Energy Mill - A mill that utilizes high speed air to reduce the size of solid particles. Fluorinated Ethylene Propylene Copolymer A random copolymer of tetrafluoroethylene and hexafluoropropylene: [

CF2

CF2

CF2

CF2

CF

CF2

CF2

]n

CF3

Fluorinated Ethylene Propylene Terpolymer Refers to FEP containing a third fluorinated

monomer. See also Fluorinated Ethylene Propylene Copolymer. Fluorine Sheath - An analogy comparing the molecule of (PTFE) polytetrafluoroethylene with a wire. Fluorine atoms form a sheath around the carbon backbone of PTFE, rendering it impervious to chemicals, resembling the function of an insulation around a conductor. Fluoroadditives - These are the finely divided low molecular weight polytetrafluoroethylene powders added to other products to impact some of the fluoropolymer properties to the host systems. Fluoroalkenes - Unsaturated linear perfluorinated hydrocarbons containing at least one double bond are called fluoroalkenes. Fluoroalkoxyphosphazene Elastomer - Fluorine-containing elastomer based on inorganic –P=N– chain linkages, with fluoroalkoxy side chains attached to P atoms. These elastomers give tough vulcanizates with excellent low-temperature characteristics, but are not currently offered commercially. Fluorocarbon Rubber - Any of several families of elastomeric copolymers with chains containing carbon-carbon linkages. See Fluoroelastomer. Fluoroelastomer - Broadly, any elastomer containing significant fluorine content. In this book, fluoroelastomer is taken as synonymous with fluorocarbon elastomer, any elastomeric copolymer with carbon-carbon chain linkages, excluding elastomers based on inorganic chain linkages (e.g., polysiloxanes or polyphosphazenes). Major monomers used for fluoroelastomers are: vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluoro(methyl vinyl ether)(PMVE), propylene (P), and ethylene (E). A number of cure site monomers or other active moieties are incorporated to facilitate curing to vulcanizates with outstanding heat stability and fluid resistance. Fluoroelastomer families are classified in ASTM categories based on major monomer compositions: FKM, copolymers of VDF/HFP/ (TFE) or VDF/PMVE/TFE; FFKM, copolymers based on TFE/PMVE or other perfluoro(alkyl vinyl ether); and FEPM, copolymers based on TFE/P or E/TFE/PMVE.

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325

Fluorohydrocarbon Resin - See Fluoropolymer. Fluoromethanes - These are methane compounds in which one or more hydrogen has been replaced by fluorine (e.g., CH2F2). Fluoroplastic - See Fluoropolymer. Fluoroplastic Homopolymer - A fluoropolymer entirely compiled of one monomer is called fluoroplastic homopolymer. Examples include polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl fluoride. Fluoropolymer – A polymer containing fluorine in one or more of its constituent monomers. The general term includes fluoroplastics and fluoroelastomers, but fluoroplastics industry usage is to consider fluoropolymers as synonymous with fluoroplastics. In fluoropolymers, some or all of the hydrogen is replaced with fluorine. Fluoropolymers are characterized by excellent chemical resistance, thermal stability, antifriction properties, antiadhesive properties, weather resistance, and low flammability. Disadvantages of fluoroplastics include low creep resistance and strength and difficulty of processing. The properties of fluoropolymers depend on fluorine content. Processing is achieved mostly by extrusion and molding. Uses include chemical apparatus, bearings, seals, tubing, films, coatings, and containers. Also called fluoroplastic, fluoroelastomer, perfluoroelastomer, fluorocarbon resin or elastomer, fluorohydrocarbon resin or elastomer, polyfluorocarbon, polyfluorohydrocarbon. Fluorosilicone (FVMQ) - See Silicone. Free Radical - An atom or group of atoms with an odd or unpaired electron. Free radicals are highly reactive and participate in free radical chain reactions such as combustion and polymer oxidation reactions. Scission of a covalent bond by thermal degradation or radiation in air can produce a molecular fragment named a free radical. Most free radicals are highly reactive because of their unpaired electrons, and have short half lives. R–R´ → R· + R´ FTIR - Fourier transform infrared spectroscopy (FTIR), is a spectroscopic technique in which a sample is irradiated with electromagnetic

energy from the infrared region of the electromagnetic spectrum (wavelength ~0.7 to 500 mm). The sample is irradiated with all infrared wavelengths simultaneously, and mathematical manipulation of the Fourier transform is used to produce the absorption spectrum or “fingerprint” of the material. Molecular absorptions in the infrared region are due to rotational and vibrational motion in molecular bonds, such as stretching and bending. FTIR is commonly used for the identification of plastics, additives, and coatings.

G Gamma Radiation - Ionizing radiation propagated by high-energy protons (e.g., emitted by a nucleus in transition between two energy levels). Gamma Ray Irradiation - A technique for crosslinking certain fluoroelastomers and perfluoroelastomers by exposing molded or extruded parts to gamma rays from a source such as 60Co. As with fluoroplastics such as polytetrafluoroethylene, high gamma ray dosage may reduce molecular weight substantially. Generator - An electronic device that converts standard 120/240 volt, 50/60 Hz line voltage into high-frequency electrical energy. Glass Transition Temperature - Temperature at which a material changes from the amorphous glassy state to an elastomeric or liquid state. As a glassy material is heated through the glass transition range, chain segment mobility increases greatly. This is a second order transition involving a change in heat capacity, often determined by Differential Scanning Calorimetry (DSC) measurements. Glow Discharge - Plasma or glow discharge is sometimes referred to as the fourth state of the matter. It is produced by exciting a gas with electrical energy. It is a collection of charged particles containing positive and negative ions. Other types of fragments such a free radicals, atoms, and molecules may also be present. Plasma is electrically conductive and is influenced by a magnetic field. Plasma is intensely reactive which is precisely the reason that it can modify surfaces of plastics.

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GPC - See SELC. Graphite Filler - A crystalline form of carbon in powder form. Graphite occurs naturally and also is produced by heating petroleum coke, carbon black, and organic materials. Used as a lubricating filler for nylons and fluoropolymers. Also called powdered graphite, plumbago, graphite powder, carbon graphite, black lead. Graphite Powder - See Graphite Filler.

H Halogenated Solvents - Organic liquids containing at least one atom of a halogen (Cl, F, I, Br) are called halogenated solvents. HDT - See Heat Deflection Temperature. Heat Affected Zone - In welding, the region of the part that is affected by heat used to melt the joining surface. Microstructure of the heat affected zone is an important determinant of the mechanical strength of the weld. Also called HAZ. Heat Deflection Temperature - The temperature at which a material specimen (standard bar) is deflected by a certain degree under specified load. Also called tensile heat distortion temperature, heat distortion temperature, HDT, deflection temperature under load. Heat Distortion Temperature (HDT) - See Heat Deflection Temperature. Heat Stability - See Thermal Stability. Heat Stabilizer - Also called thermal stabilizers or thermostabilizers. Compounds that help avert and/or neutralize the factors damage a polymer as a result of heating during its preparation, compounding, fabrication, or use. The purpose of heat stabilization is to maintain the original properties/characteristics of the product and assure its desired service life. Hexafluoropropylene, (HFP) - CF3 — CF = CF2 HFP - See Hexafluoropropylene. Hold Time - In welding, the length of time allotted for the melted plastic to solidify. In process engineering, the residence time of an individual ingredient in reaction vessel or other

processing apparatus. Also called holding time, holdup time. Homogeneous Nucleation - Mechanism of formation of polymer particles in an emulsion polymerization, wherein monomer propagation in the aqueous phase leads to oligomeric radicals of sufficient size to coagulate into precursors of particles which grow by continued propagtion and entry of other radicals from the aqueous phase. Homopolymer - A polymer that contains only a single type of monomer (i.e., propylene). Hot Melt Adhesive - An adhesive that is applied in a molten state which forms a bond after cooling to a solid state. Acquires adhesive strength through cooling, unlike adhesives that achieve strength through solvent evaporation or chemical cure. Hydrocarbon - A chemical compound that contains only hydrogen and carbon atoms. Hydrofluoric Acid - HF is a highly corrosive acid. Hydrogenated Nitrile Rubber (HNBR) - A modified version of nitrile rubber (NBR) in which most of the double bonds of the butadiene/acrylonitrile copolymer are removed by hydrogenation, leaving only a small fraction to allow curing. HNBR has improved thermal resistance over NBR, while retaining toughness and oil resistance. Hydrophilic Surface - Surface of a hydrophilic substance that has a strong ability to bind, adsorb or absorb water; a surface that is readily wettable with water. Hydrophilic substances include carbohydrates such as starch. Hysteresis - Lack of retraceability of a property of a material. For example, after a fluoroelastomer vulcanizate is subjected to tensile stress, the induced strain may not completely disappear when the stress is removed. Hysteresis Loop - A plot showing the effect of retarded response of a material property to changes in forces acting upon a body. For example, the trace of strain on a fluoroelastomer vulcanizate versus applied stress may not be the same for initial increasing stress as for subsequent decreasing stress. Often the material retains significant strain (“set”) after removal of the stress.

GLOSSARY

327

I Impact Strength - The energy required to break a specimen, equal to the difference between the energy in the striking member of the impact apparatus at the instant of impact with the specimen and the energy remaining after complete fracture of the specimen. Also called impact energy. Impregnation - A term applied to filling or saturating a porous material such as glass cloth or fabric with a polymer dispersion. Infrared Oven - An oven equipped with infrared lamps where heat is generated by infrared rays. Initiation – Initial step in free radical polymerization, which involves formation of free radicals and addition of monomer units to start growing chains. Ordinarily, free radicals are formed by thermal decomposition of a peroxide or reaction of a peroxide with a reducing agent. In emulsion polymerization, the usual initiator is a water-soluble persulfate which decomposes to form radicals in the aqueous phase; these grow into oligomeric radicals which enter monomerswollen polymer particles for further propagation to high polymer. In solution or suspension polymerization, oil-soluble peroxides are used to generate radicals in the solution or monomer-swollen polymer particles. Injection Molding - A molding procedure in which a heat-softened plastic or elastomeric material is forced from a cylinder into a cavity which gives the article the desired shape. The process is used for all thermoplastics, with the mold cavity cooled to harden the part. It is also used for thermoset elastomers, with the mold cavity heated to induce curing (crosslinking) of the part. Insulator - Nonconductive dielectric films used to isolate electrically active areas of the device or chip from one another. Some commonly used insulators are silicon dioxide, silicon nitride, borophospho-silicate glass (BPSG), and phosphosilicate glass (PSG). Interference Fit - A mechanical fastening method used to join two parts, such as a hub and a shaft, in which the external diameter of the shaft is larger than the internal diameter of the hub. This interference produces high stress in the

material and must be determined carefully to avoid exceeding the allowable stress for the material. Stress relaxation can occur in interference fits, causing the joint to loosen over time. Also called press fit. Integrated Circuit (IC) - A fabrication technology that combines components of a circuit on a wafer. Intermolecular Forces - See also Van der Waals Forces. Internal Mixer – One of a family of batch mixers used to masticate rubber and disperse fillers and cure system ingredients in rubber compounds. These mixers have rotors with close clearances to impart high shear to the rubber. See Banbury Mixer. Iodotetrafluorobutene (ITFB) - A cure site monomer incorporated in some fluoroelastomers to allow free radical curing; ITFB is 4iodo-3,3,4,4-tetrafluorobutene-1, CH2=CH– CF2–CF2I. Elastomers containing this monomer are susceptible to branching by transfer reactions involving iodine of ITFB monomer units incorporated in polymer chains. Ion Implantation - A process technology in which ions of dopant chemicals (boron, arsenic, etc.) are accelerated in intense electrical fields to penetrate the surface of a wafer, thus changing the electrical characteristics of the material. Ionic Strength - This is a property of solutions containing ions. An increase in the concentration and the number of soluble salts in water increase the ionic strength of the solution. For a solution containing salts each with a molarity of mi , (i = 1, 2, …, k) and a valence of Zi , ionic strength (I ) is calculated from the following expression:

∑ (m Z ) k

i

2 i

i =1

Irradiation - See Gamma Ray Irradiation. Isoparaffinic Hydrocarbon - A hydrocarbon that contains branches in its chemical structure. Izod - See Izod Impact Energy. Izod Impact Energy - The energy required to break a v-notched specimen equal to the

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difference between the energy in the striking member of the impact apparatus at the instant of impact with the specimen and the energy remaining after complete fracture of the specimen. For metals, it is measured according to ASTM E23. Also called notched Izod strength, notched Izod impact strength, Izod v-notch impact strength, Izod strength, Izod impact strength, Izod, IVN. Izod Impact Strength - See Izod Impact Energy. Izod Strength - See Izod Impact Energy. Izod v-Notch Impact Strength - See Izod Impact Energy.

Linings or liners are either inserted or formed in-place and are usually thicker than coatings fabricated from a dispersion. LOI - See Limiting Oxygen Index. Low Pressure CVD or LPCVD - It refers to systems that process wafers in an environment with less than atmospheric pressure. LPCVD systems may be furnaces that process wafers in batches, or single-wafer systems Lubricants - Oils or greases used to reduce friction between moving surfaces (e.g., between metal parts in engines or transmissions).

M J Joining - See Adhesive Bonding.

L Lap Joint - A joint in which one adherend is placed partly over the other adherend; overlapped areas are bonded together. Laser - A device used to produce an intense light beam with a narrow band width. Laser is an acronym for light amplification by stimulated emission of radiation. Lewis Base - A substance that donates a pair of electrons in a chemical reaction to form a bond with another substance. Limiting Oxygen Index (LOI) - LOI is defined as the required minimum percentage of oxygen in a mixture with nitrogen, which would allow a flame to be sustained by an organic material such as a plastic. Linear Polyethylenes - Linear polyethylenes are polyolefins with linear carbon chains. They are prepared by copolymerization of ethylene with small amounts of higher alpha-olefins such as 1-butene. Linear polyethylenes are stiff, tough and have good resistance to environmental cracking and low temperatures. Processed by extrusion and molding. Used to manufacture film, bags, containers, liners, profiles, and pipe. Linings - Inserts, usually made from plastics to protect metallic or nonmetallic substrates.

Macroscopic Flaws - Defects such as cracks or inclusions in fluoropolymer parts which can be detected visually or by the use of a simple magnifying glass. Mandrels - Hard parts (normally metallic) which are inserted in mold to obtain desired part geometries. For example, a solid metal mandrel is placed inside an isostatic cylindrical mold in order to obtain a polytetrafluoroethylene liner. Mark-Houwink Equation – Empirical relation between intrinsic viscosity [η] and viscosity average molecular weight Mv: [η] = KMvα, where the parameters K and α depend on solvent-polymer interaction. For vinylidene fluoride-based fluoroelastomers dissolved in a polar solvent such as methyl ethyl ketone or dimethylacetamide, α is in the range 0.6 to 0.8, increasing with vinylidene fluoride content of the elastomer. This relationship, valid for linear polymer chains, is the basis for calibration of SELC for measurement of molecular weight distribution. See SELC, Molecular Weight Distribution. Mask - A flat, transparent plate that contains the photographic image of wafer patterns to define one process layer. MDR - Moving Die Rheometer, developed by Monsanto for characterization of cure rate and state of elastomer compounds. Sample size used in MDR measurements is smaller than that used in ODR machines, so onset of curing is faster and MDR simulates curing in an injection molding process better than ODR.

GLOSSARY

329

Melting Point - The temperature at which the solid crystalline and liquid phases of a substance are in thermodynamic equilibrium. The melting point is usually referred to normal pressure of 1 atm.

Microporosity - Defects such as small voids or inclusions in fluoropolymer parts which can be detected by a microscope or the use of a fluorescent dye.

Melt Processible Polymer - A polymer that melts when heated to its melting point and forms a molten material with definite viscosity value at or somewhat above its melting temperature. Such a melt should be pumpable and flow when subjected to shear rate using commercial processing equipment such as extruders and molding machines.

Microprocessor - An integrated circuit that contains the basic arithmetic, logic, and control circuitry required for processing.

Metallization - The deposition of a layer of highconductivity metal such as aluminum used to interconnect devices on a chip by CVD or PVD. Metals typically used include aluminum, tungsten, and copper. Methylene Iodide - A chain transfer agent used to control molecular weight and incorporate iodide end groups reactive for free radical curing of fluoroelastomers. In one family of fluoroelastomers, methylene iodide is used along with another cure site monomer. Mica - Mica is a crystalline platy filler made by wet or dry grinding of muscovite or phlogopite, minerals consisting mainly of aluminum and potassium orthosilicates, or by chemical reaction between potassium fluorosilicate and alumina. Used as a filler in thermosetting resins to impart good dielectric properties and heat resistance, and in thermoplastics such as polyolefins to improve dimensional stability, heat resistance, and mechanical strength. Mica fillers also reduce vapor permeability and increase wear resistance. Mica fillers having increased flake size or platiness increase flexural modulus, strength, heat deflection temperature, and moisture resistance. Surface modified grades of mica are available for specialty applications. Micellar Nucleation - Mechanism of formation of polymer particles in an emulsion polymerization, wherein small oligomeric radicals and monomer are taken up in surfactant micelles, and subsequent propagation leads to particles containing high polymer. Micron - A unit of length equal to 1 × 10-6 meter. Its symbol is Greek small letter mu (µ).

Milling - A process for masticating rubber or mixing rubber compounds, using a two-roll mill. The mill rolls are arranged side by side with a variable small space (nip) between the parallel rolls. The rolls are driven in opposite directions, with 15%–30% differential speed to impart high shear to rubber passing through the nip. Part of the rubber is in a rolling bank above the nip, and the rest is in a tight band around one roll. The band may be cut diagonally and the sheet folded back to facilitate mixing. For compounding, the elastomer is usually banded first, then other ingredients are added by feeding into the nip area. The mixed compound is removed as a sheet from the mill for further processing. Mineral Filler - Mineral fillers are a large subclass of inorganic fillers comprised of ground rocks or natural or refined minerals. Some fillers, so-called commodity minerals, are relatively inexpensive and are used mostly as extenders. A good example of these is ground limestone. Other fillers, so-called specialty minerals, are usually reinforcing fillers. These are inherently small particle size fillers, such as talc, and surface chemically modified fillers. See also Organic Filler. Modifier - An additive that alters the properties of the host system. In free radical polymerization, a chain transfer agent which reduces polymer molecular weight is often referred to as a modifier. Moisture Vapor Permeation - Refers to permeation of water vapor through films and membranes which can be measured by a number of standard methods (e.g., ASTM). Mold Shrinkage - The difference between the dimension(s) of the mold cavity at 23°C and the dimension(s) of specimen molded. Measured for plastics after cooling the molding to room temperature according to ASTM D955. Molecular Weight - The molecular weight (formula weight) is the sum of the atomic weights

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of all the atoms in a molecule (molecular formula). Also called MW, formula weight, average molecular weight. Molecular Weight Distribution - The relative amounts of polymer chains of different molecular weights that comprise a given sample of polymer. Molecular weight distribution is usually measured by Size Exclusion Liquid Chromatography (SELC; see entry). Molecular weights are expressed in units of g/mole or dalton (for high polymers, sometimes expressed in this book as kg/mole or kdalton). Molecular weight distribution (polydispersity) is often characterized in terms of the ratio of weight average to number average molecular weight, Mw/Mn. However, this measure of distribution may not be adequate to characterize important characteristics of an elastomer. Several molecular weight averages, obtained from different types of measurements on dilute polymer solutions, may be used as measures of various polymer characteristics, as listed below. Number average molecular weight Mn, total mass per mole of all species, is defined as

measured by light scattering, and is influenced mainly by the fraction of high molecular weight chains present. Bulk viscosity of elastomers correlates well with Mw. A higher moment of the molecular weight distribution, the z-average molecular weight Mz, is defined by ∞

∑N M i

Mz =

3 i

i =1 ∞

∑N M i

2 i

i =1

and is measured by sedimentation equilibrium using an ultracentrifuge. Mz is influenced by the fraction of very long chains present; the presence of significant high molecular weight tail in the distribution may lead to high green strength and modulus of an elastomer. Viscosity average molecular weight Mv is defined from intrinsic viscosity measurements (see Solution Viscosity) using the Mark-Houwink equation (see entry) as

∞

∑ Mn =

NiMi

∞ α M v =  w i Mi    i =1

∑

i =1 ∞

∑

Ni

i =1

where Ni is the number of moles of species i with molecular weight Mi. Mn is measured by colligative properties in dilute solution, usually by osmotic pressure. Mn is influenced largely by the fraction of low molecular weight chains present; elastomers with low Mn may be difficult to cure adequately for acceptable mechanical properties. Weight average molecular weight Mw is defined as ∞

∑N M

∞

Mw =

∑w M i

i =1

i

i

=

2

∑

1/ α

∑

where the parameter α depends on the polymer-solvent system, usually having a value of 0.6 to 0.8 for VDF-containing fluoroelastomers in polar solvents. Mv is usually slightly lower than Mw. Monomer - The individual molecules from which a polymer is formed. For fluoroelastomers, major monomers include vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, perfluoro(methyl vinyl ether), propylene, and ethylene.

i

i =1 ∞

∑N M i

1/ α

 ∞ 1+ α   Ni Mi   =  i =1∞   Ni Mi    i =1 

i

i =1

where wi is the weight fraction of species “i” with molecular weight M i . M w is usually

Mooney Viscosity - A measure of bulk viscosity at low shear rate of an elastomer or uncured rubber compound. The elastomer is contained in a cavity formed between two platens maintained at a set temperature, and is molded around a serrated disk rotor. Rotation is delayed

GLOSSARY

331

for a set time after closing the platens, then started at a low rate. Torque is recorded versus time; the Mooney viscosity is the torque reading in arbitrary units after a chosen time. Measurement temperature is chosen to be high enough to break down crystallinity or ionic associations, so the final torque reflects the molecular weight and chain structure of the elastomer. A typical Mooney viscosity of a fluoroelastomer would be denoted as ML (1 + 10) at 121ºC or ML-10 (121ºC), referring to a Mooney torque value measured after 1 minute delay followed by 10 minutes of rotation with a stock temperature of 121ºC. Such relatively long rotation periods are necessary for fluoroelastomers, since their long relaxation times result in long times for establishment of steady flow around the rotor and nearly constant torque readings. Mooney viscosity values are reliable over a range of about 10 to 100 units; different temperatures may be chosen for very low or very high molecular weight elastomers to get readings in this range. MTBE - Methyl tertiary-butyl ether, an oxygenated gasoline additive used to boost octane number while reducing tailpipe emissions. Multilayer Coating - A coating that is produced by multiple passes of the substrate through the coating process. After each pass the thickness of the coating increases. Multilayer coating is a means of overcoming critical cracking thickness when relative thick coatings are required.

N Nanometer - A unit of length equal to 1 × 109 meter. Often used to denote the wavelength of radiation, especially in UV and visible spectral region. Also called nm. Newtonian Fluid - A term to describe an ideal fluid in which shear stress and shear rate is proportional (e.g., water). The proportionality coefficient is called viscosity, which is independent of shear rate, contrary to non-deal fluids where viscosity is a function of shear rate. Paints and polymer melts are examples of nonNewtonian liquids. Nitrile Rubber (NBR) - Rubber family based on copolymers of butadiene with acrylonitrile;

NBR with high acrylonitrile content is oil resistant. Sulfur-cured NBR vulcanizates are characterized by good physical properties and intermediate heat resistance. See Hydrogenated Nitrile Rubber (HNBR). Nonpolar - In molecular structure, a molecule in which positive and negative electrical charges coincide. Most hydrocarbons, such as polyolefins, are nonpolar. Notch Effect - The effect of the presence of specimen notch or its geometry on the outcome of a test such as an impact strength test of plastics. Notching results in local stresses and accelerates failure in both static and cycling testing (mechanical, ozone cracking, etc.). Notched Izod Impact Strength - See Izod Impact Energy. Notched Izod Strength - See Izod Impact Energy. Nuclear Magnetic Resonance (NMR) – A physical phenomenon involving the interaction of atomic nuclei placed in a static external magnetic field with an applied electromagnetic field oscillating at a particular frequency. Magnetic conditions within the material are measured by monitoring the radiation absorbed and emitted by the atomic nuclei. NMR is used as a spectroscopic technique to obtain detailed information on composition and structure of polymers. Only nuclei with non-zero magnetic moment (odd number of protons or neutrons) can undergo NMR; of these, NMR measurements based on 1H, 13C, and 19F are useful for fluoroelastomer analysis. NMR is useful for determining the relative amounts and sequencing of certain structures, but is not usually used for routine, accurate composition analysis of fluoroelastomers. Nucleation – Formation of precursors to polymer particles in emulsion polymerization. See Homogeneous Nucleation, Micellar Nucleation. Nucleophile - Nucleophiles or Nucleophilic reagents are basic, electron-rich reagents. Negative ions and chemical groups can be nucleophiles, in addition to neutral compounds such as ammonia and water. Both ammonia and water molecules contain a pair of unshared electrons.

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Nylon - Nylons are thermoplastic, mostly aliphatic polyamides prepared usually either by polymerization of dicarboxylic acid with diamine, or polymerization of amino acid, or ring opening polymerization of lactam. Nylons have good resistance to solvents, bases, and oils; to impact; abrasion; and creep. They have also high tensile strength and barrier properties, and a low coefficient of friction. The disadvantages include high moisture pickup, light degradation, and high mold shrinkage. Processing is achieved by injection, blow, and rotational molding; extrusion; and powder coating. Uses are automotive parts, electrical and electronic devices such as plugs, machine parts such as gears and pumps, housings for appliances and power tools, wire and cable jacketing, pipes, films, and fibers.

O ODR - Oscillating Disc Rheometer, used for characterizing rate and state of cure of elastomer compounds. Peak torque measured by an oscillating disc in contact with a rubber compound is recorded versus time at a set cure temperature. Parameters usually reported are the minimum torque obtained before the start of cure and maximum torque obtained at the end of curing, along with the time required for the onset of curing and the time required to reach 90% of the increase in torque. Cure times observed by ODR often approximate cure times required in compression molding of parts. Organic Compound - A chemical compound that contains one or more carbon atoms in its molecular structure. Organic Filler - Organic fillers are made from natural or synthetic organic materials. Natural material derived organic fillers include wood and shell flours. Synthetic material derived fillers include fluoropolymer spheres and milled polymer waste. Organic fillers are characterized by relatively low cost and low density. They might increase the flammability and decrease the moisture resistance of plastics. See also Mineral Filler. Orientation - A process of drawing or stretching fibers, films, or tubing to orient polymer mol-

ecules in the direction of stretching. The process is used mainly for thermoplastics to get enhanced mechanical properties, but may be applied to semicrystalline elastomers. Oriented Film - See Orientation. OSHA - Occupational Safety and Health Administration Oxygen Sensor - A sensor in automobiles senses the oxygen content of the exhaust gas. Ozone - O3.

P Paraffins - Linear saturated hydrocarbons with the general chemical formula of CnH2n+2. Passivation - The final layer in a semiconductor device, that forms a hermetic seal over the circuit elements. Plasma nitride and silicon dioxide are the materials primarily used for passivation. Pascal - An SI unit of pressure, abbreviated as Pa, equal to the force of one Newton acting uniformly over an area of one square meter. Used to denote the pressure of gases, vapors, or liquids and the strength of materials. In elastomer technology, the unit MPa, equal to 145 psi, is useful for expressing process pressures and vulcanizate modulus and tensile strength. PCTFE - See Polychlorotrifluoroethylene. Peel Strength - The bond strength of a film adhered by an adhesive to a substrate is measured by different techniques and is called peel strength. An extensiometer can be used to measure peel strength. Pendant Methyl Group - A methyl (CH3) functional group attached to the main chain of a polymer molecule. Perfluorinated Fluoropolymers - Polymer consisting of only carbon and fluorine (and an occasional oxygen atom) atoms are called perfluorinated fluoropolymers. Perfluorinated Paraffins - Refers to a linear saturated hydrocarbon where all hydrogen atoms have been replaced with fluorine, with the general chemical formula of CnF2n+2.

GLOSSARY

333

Perfluoroalkoxy (PFA) Polymer - Rf represents a perfluorinated alkyl group containing one or more carbon atoms, typically a maximum of four carbon atoms. CF2

CF2

CF

CF2

O

centrations and death. Wheezing, sneezing, difficulty breathing and deep or rapid breathing are among the symptoms. Animals that survived twenty four hours after exposure recovered with no after-effects. Perfluoromethyl Vinyl Ether - See Perfluoroalkyl vinyl ether. CF3—O—CF=CF2

Rf

Perfluoroalkyl Vinyl Ether (PAVE) Rf —O—CF=CF2

Perfluoropolymer - See Perfluorinated Fluoropolymer. Perfluoropropylvinylether (PPVE) -

where Rf is a perfluorinated alkyl group containing one or more carbon atoms, typically a maximum of four carbon atoms.

CF3

CF

O

CF

CF2

CF3

Perfluoroammoniumoctanoate - (C8).

O CF3

(CF2)6

C

O

NH4

Perfluoroelastomer – A fluoroelastomer (ASTM designation FFKM) based on perfluorinated major monomers. FFKM elastomers made by DuPont Dow and most other suppliers are copolymers of tetrafluoroethylene (TFE) with perfluoro(methyl vinyl ether) (PMVE); Daikin FFKM is a copolymer of TFE with a higher molecular weight perfluoro(alkyl vinyl ether). Environmental resistance of FFKM vulcanizates approaches that of perfluoroplastics such as polytetrafluoroethylene. Several cure systems have been developed to obtain high heat stability (long service life up to 300°C) and chemical resistance approaching that of the base polymer. Perfluoroethyl Vinyl Ether - Also see Perfluoroalkyl Vinyl Ether. CF3—CF2—O—CF=CF2 Perfluoroisobuthylene (PFIB ) CF3C

CF2

CF3

Animal studies of PFIB inhalation indicate occurrence of severe adverse including pulmonary edema as a result of exposure to high con-

Permeability - The capacity of material to allow another substance to pass through it; or the quantity of a specified gas or other substance which passes through under specified conditions. Peroxydicarbonate Initiator – An oil-soluble initiator such as diisopropyl peroxydicarbonate suitable for generating free radicals in a fluoroelastomer suspension polymerization at temperatures of 40°C to 60°C. The general structure of this type of initiator, where R is an alkyl group such as isopropyl, is:

R O C O O C O O

R

O

Persulfate Initiation - This is in reference to the action of water-soluble persulfates such as ammonium persulfate in generating free radicals in the emulsion polymerization of elastomers or in dispersion polymerization of fluoroplastics. Peroxide Cure - Cure system based on free radicals generated by thermal decomposition of a peroxide at curing temperatures. The primary free radicals generated, typically methyl radicals, react with an unsaturated radical trap such as triallyl isocyanurate. The radicals on the trap undergo transfer reactions with sites (usually I or Br) on polymer chains to form in-chain radicals which add to allyl groups of trap molecules to form crosslinks. Polymerization of the multifunctional trap also occurs, as well as some reaction of primary radicals with sites on chains.

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Petroleum Solvents - A solvent that is derived from processing petroleum. PFA - See Perfluoroalkoxy Polymer. PFIB - See Perfluoroisobuthylene. Photolithography - A process by which a mask pattern is transferred to a wafer, usually using a “stepper.” Photoresist - A light-sensitive organic polymer that is exposed by the photolithography process, then developed to produce a pattern which identifies some areas of the film to be etched. Physical Vapor Deposition or PVD - Also called sputtering, is a process technology in which molecules of conducting material (aluminum, titanium nitride, etc.) are “sputtered” from a target of pure material, then deposited on the wafer to create the conducting circuitry within the chip. Plasma - Ionized gases that have been highly energized-for example, by a radio frequency energy field. See also Glow Discharge. Plasma Arc Treatment - In adhesive and solvent bonding, a method for treating the surfaces of parts prior to solvent and adhesive bonding, in which an electrical current between two electrodes in a gas at low pressure excites the gas particles, producing free radicals. Contaminants are stripped from the surface of the part, and wettability is increased by reduction of the contact angle. Also called plasma discharge, plasma treatment. See also Corona Discharge Treatment. Plasma Enhanced Chemical Vapor Deposition or PECVD - It is a process where plasma is used to lower the temperature required to deposit film onto a wafer. Polar - In molecular structure, a molecule in which the positive and negative electrical charges are permanently separated. Polar molecules ionize in solution and impart electrical conductivity to the solution. Water, alcohol, and sulfuric acid are polar molecules; carboxyl and hydroxyl are polar functional groups. Polychlorotrifluoroethylene (PCTFE) [—CF2—CFCl—]n

Thermoplastic prepared by radical polymerization of chlorotrifluoroethylene. It has good transparency and great barrier properties. Dielectric properties and resistance to solvents, especially chlorinated, of PCTFE are somewhat lower than those of perfluoropolymers, but tensile strength and creep resistance are higher. Processing is difficult, because of high melt viscosity, but possible by extrusion, injection molding, compression molding, and coating. Uses include chemical apparatus, cryogenic seals, films, and coatings. Also, PCTFE spheres are used as fillers and PCTFE oil is used as a lubricant in various plastics. Polyethylene (PE) - A family of polyolefins consisting of linear and branched polyethylenes. Polyethylenes are thermoplastics but can be cross-linked by irradiation or chemically and then show improved strength and dielectric properties. All linear polyethylenes, except the high density grade, are prepared by copolymerization of ethylene with higher olefins. Branched polyethylenes are prepared from ethylene alone or together with polar comonomers such as vinyl acetate. The density, melt index, crystallinity, degree of branching, molecular weight, polydispersity, and related properties of polyethylenes vary widely depending on the catalysts and methods of polymerization and on modifying comonomers and treatments. Polyethylenes have good impact resistance at low temperatures, good chemical resistance, and good moisture resistance, but high thermal expansion, poor weatherability, poor thermal stability and resistance to stress cracking. They are readily processible by all thermoplastic methods but are flammable and difficult to bond. Food grades are available. Processed by extrusion, blow and injection molding, thermoforming. Used very broadly as films, coatings, in containers and consumer goods, electrical insulation, and piping. Also called PE, expandable polyethylene bead, EPE bead. Polymer - Polymers are high molecular weight substances with molecules resembling linear, branched, cross-linked, or otherwise shaped chains consisting of repeating molecular groups. Synthetic polymers are prepared by polymerization of one or more monomers. The monomers comprise low-molecular-weight reactive

GLOSSARY substances, often containing more than one reactive molecular bond or chemical bond. Natural polymers have molecular structures similar to synthetic polymers but are not man made, occur in nature, and have various degrees of purity. Also called synthetic resin, synthetic polymer, resin, plastic. Polymer Fume Fever - A condition that occurs in humans as a result of exposure to degradation products of polytetrafluoroethylene and other fluoropolymers. The symptoms of exposure resemble those of flu and are temporary. After about twenty-four hours, the flu-like symptoms disappear. Polyolefin - Polyolefins are a large class of carbon-chain elastomeric and thermoplastic polymers usually prepared by addition (co)polymerization of olefins or alkenes such as ethylene. The most important representatives of this class are polyethylene and polypropylene. There are branched and linear polyolefins and some contain polar pendant groups or are halogenated. Unmodified polyolefin are characterized by relatively low thermal stability and a nonporous, nonpolar surface with poor adhesive properties. Processed by extrusion, injection molding, blow molding, and rotational molding. Other thermoplastic processes are used less frequently. This class of plastics is used more and has more applications than any other. Also called olefinic resin, olefinic plastic. Polypropylene (PP) - PP is a carbon chain thermoplastic comprised of propylene homopolymer prepared by stereospecific polymerization in the presence of Ziegler Natta catalysts. The majority of PP is isostatic. PP has low density and good flexibility and resistance to chemicals, abrasion, moisture, and stress cracking, but decreased dimensional stability, mechanical strength, and resistance to UV light and heat. PP is flammable. Processed by injection molding, spinning, extrusion, and film techniques. Used as films for pressure sensitive tapes, packaging, liners, and shrink films, and as fibers in textiles. Also called PP homopolymer, PP, polypropylene homopolymer, expandable polypropylene bead, EPP bead.

335 Polysilicon - Polycrystalline silicon; extensively used as conductor/gate materials in a highly doped state. Poly films are typically deposited using high-temperature CVD technology. Polytetrafluoroethylene - Thermoplastic prepared by radical polymerization of tetrafluoroethylene. It has low dielectric constant, superior chemical resistance, very high thermal stability, low friction coefficient, excellent antiadhesive properties, low flammability, and high weatherability. Impact resistance of PTFE is high, but permeability is also high whereas strength and creep resistance are relatively low. The very high melt viscosity of PTFE restricts its processing to sinter molding and powder coating. Uses include coatings for cooking utensils, chemical apparatus, electrical and nonstick items, bearings, and containers. Also, PTFE spheres are used as fillers and PTFE oil is used as a lubricant in various plastics. Also called TFE, PTFE, modified PTFE. Polytetrafluoroethylene Compounds - Material obtained by intimate mixing of fillers (metallic and nonmetallic) with polytetrafluoroethylene. One or more of polymer properties such as cold flow, wear, and surface hardness are altered by the addition of fillers. Polyvinyl Chloride (PVC) - PVC is a thermoplastic prepared by free-radical polymerization of vinyl chloride in dispersion (emulsion), bulk, or suspension processes. A small amount of comonomer is sometimes added to enhance adhesion or other properties. Unmodified PVC is rigid and requires plasticizers to make it more flexible. The main end forms of PVC are rigid and flexible. The flexible form is often made from plastisols, suspensions of PVC in liquid plasticizers. PVC can be chlorinated to increase its heat deflection temperature and tensile strength and to reduce flammability and smoke generation. PVC is dimensionally stable, largely nonflammable, and resistant to weathering, but has limited thermal stability, high density, and is attacked by many solvents. Processed by injection molding, calendaring, extrusion, powder coating, blow molding, extrusion coating, and film techniques. Used very widely as films, fabric coatings, wire coatings, toys, bottles, and pipes.

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Polyvinyl Fluoride (PVF) [—CH2—CHF—]n Thermoplastic prepared by free radical polymerization of vinyl fluoride. It is extruded into thin (<100 µm) films as a plastisol (dispersion in a polar solvent). PVF is known for its weather resistance, release, adherability, and mechanical strength. Polyvinylidene Fluoride (PVDF) [—CF2—CH2—]n Thermoplastic prepared from vinylidene fluoride. It has substantially higher strength, wear resistance, and creep resistance than other fluoropolymers but relatively high dielectric constant and loss factor. PVDF is nonflammable, resists most solvents, and has excellent weatherability. Its service temperature limit and chemical resistance are lower than those of perfluoropolymers. PVDF is processed readily by extrusion, injection molding, transfer molding, and powder or dispersion coating. Uses include electrical insulation, pipes, chemical apparatus, coatings, films, containers, and fibers. Also called VF2, PVF2, PVDF. Porosity - Porosity is defined as the volume of voids per unit volume of a material or as the volume of voids per unit weight of material. Post Cure - Curing of crosslinked molded parts in an oven (air or nitrogen atmosphere) for an extended time, ranging from 1 to 40 hours depending on the fluoroelastomer system involved. Post curing completes the crosslinking reactions, and removes volatile by-products and additives to obtain enhanced, stable physical properties. Preform - A shape produced by the compaction of an elastomer or its filled compound. The preform is subsequently molded and cured to form a useful part. Preforming - The process of producing a preform of an elastomer compound, usually involving milling to form a sheet or extruding to form a rod or tube which can be cut to the size desired for placing in mold cavities for subsequent curing into useful articles. Press Cure - Curing in a closed mold to effect crosslinking of an elastomer compound into a part of desired shape.

Pressure Hoses - Reinforced hoses composed of elastomer tube and reinforcement, usually in the form of single or multiple elastomer plies with metal or fiber braiding, for super-atmospheric pressure end uses. Pressure Sensitive Adhesive - An adhesive that requires applied pressure on the parts for bonding to occur. Usually composed of a rubbery elastomer and modifying tackifier, pressure sensitive adhesives are applied to the parts as solvent-based adhesives or hot melts; curing does not usually occur. They adhere tenaciously under slight pressure and are highly thixotropic. Disadvantages include limited temperature capability and susceptibility to oxidative degradation. These adhesives do not undergo progressive viscosity increase like other adhesives but instead they are in a permanent tacky stage. They are usually coated on paper, plastic films, foam or cloth and applied with pressure to the adherend, as their name implies. Most pressure sensitive adhesives contain a blend of elastomers like SBR or natural rubber with low or medium tacky fibers. See also Contact Adhesive. Primer - In adhesive bonding, a reactive chemical species dispersed in a solvent that is applied to the part surface by spraying or brushing. After the solvent is flashed off, the part surface may be bonded immediately, as in polyolefin primers for cyanoacrylates, or may require time to react with atmospheric moisture, as in silane and isocyanate-based primers used for silicone and polyurethane-based adhesives, respectively. Primers generally contain a multifunctional chemically reactive species capable of acting as a chemical bridge between the substrate and the adhesive. Primers are commonly used with acetals, fluoropolymers, polybutylene terephthalate, silicone, polyurethane, and polyolefins. In coatings, coatings applied on a substrate prior to subsequent coatings or topcoat in order to seal the pores, improve adhesion of the topcoat, improve corrosion protection, hide surface imperfections or color, etc. Usually based on polymers with functional additives. Applied by the same techniques as coatings. Also called primer coating. Process - A group of sequential operations in the manufacture of an integrated circuit.

GLOSSARY

337

Process Chamber - An enclosed area in which a process-specific function occurs during wafer manufacturing. Propagation - Addition of monomer units to a growing free radical chain, usually a fast reaction. In a copolymer, reactivity of a given monomer toward propagation depends on the nature of the last unit added to the chain. PTFE - See Polytetrafluoroethylene. PTFE Fiber - This is a polytetrafluoroethylene (PTFE) yarn produced by spinning of a blend of PTFE and viscose followed by chemical conversion, drying, and sintering. PVC - See Polyvinyl Chloride. PVDF - See Polyvinylidene Fluoride. PVF - See Polyvinyl Fluoride.

Q Quaternary Ammonium Accelerator - A salt such as tetrabutylammonium hydrogen sulfate used as an accelerator in a bisphenol cure. See Bisphenol Cure. Quaternary Phosphonium Accelerator -A salt such as benzyltriphenylphosphonium chloride used as an accelerator in a bisphenol cure. See Bisphenol Cure.

R Radiation Dosage - See Radiation Dose. Radiation Dose - Amount of ionizing radiation energy received or absorbed by a material during exposure. Also called radiation dosage, ionizing radiation dose. Radiation Resistant Materials - Materials that resist degradation on long- and medium-term or repeated exposure to ionizing radiation (e.g., steel grades designed for nuclear reactors). Radiation damage to materials includes swelling, radiolysis, blistering, changes in electrical and mechanical properties, etc. There are different mechanisms of radiation damage but most can be linked to free-radical reactions. The resistance of materials to radiation can be improved by stabilizing them with agents that can neutralize free radicals, such as dimethyl

sulfoxide, carbohydrates, and various reducing agents. Also called radiation stabilized material. Radicals - See Free Radicals. Ram Extrusion - Ram extrusion is often used for producing rod or tubing which is cut into preforms of fluoroelastomer compounds for loading into molds for curing. The elastomer compound is usually milled into a thick sheet which is rolled into a billet of suitable size for charging to the ram extruder. The billet is heated and compacted with venting of air prior to extrusion through the die. Ram extruders may also be used to feed controlled amounts of elastomer compound to mold cavities as part of an injection molding process. Rapid Thermal Processing or RTP - It is a process in which a wafer is heated to a specified temperature for short periods of time. Reactive Ion Etch or RIE - A combination of chemical and physical etch processes carried out in a plasma. Reactivity Ratio - Relative reactivity toward propagation of a radical ending in one monomer with the same monomer compared to that of a different monomer adding to the radical. For a copolymer of monomers 1 and 2, the reactivity ratio r1 is the ratio of the propagation rate coefficient k11 for addition of monomer 1 to a radical chain ending in monomer 1 to the rate coefficient k12. Likewise, reactivity ratio r2 = k22/k21. Use of reactivity ratios allows correlation of copolymer composition with monomer ratios required to make the composition, and also allows calculation of monomer sequence distributions (see Ch. 4, Secs. 4.3.2 and 4.6.3). Relaxation Time - Maxwell proposed a model in the 19th century to describe the time-dependent behavior of viscous materials such as pitch or tar. This model has also been applied to plastics and polymers. A parameter has been defined in this model called relaxation time that is a characteristic of the plastic material. Relaxation time is the ratio of viscosity to the Young’s modulus of elasticity. Repro - This is short for “reprocessed” and is applicable to recovery of scrap compound

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FLUOROELASTOMERS HANDBOOK

generated during processing of fluoroelastomers. Uncured scrap may be blended back into compound of the same composition for subsequent molding. Cured scrap may be ground and mixed into uncured compound at low levels prior to molding. Use of repro is limited because of deleterious effects on key properties of fluoroelastomer parts. Repulsive Intermolecular Forces - Forces generated when atoms or molecules approach each other closely. Reticle - A flat, transparent plate used in a stepper, that contains the photographic image of wafer patterns to be reproduced on a wafer. Rheology - A science that studies and characterizes flow of polymers, resins, gums, and other materials.

S Scorch - Premature crosslinking of an elastomer compound during processing. It is desirable for crosslinking to be negligible for time periods of 20 minutes or more at temperatures near 120ºC. SELC - Size Exclusion Liquid Chromatography, also known as Size Exclusion Chromatography (SEC) and Gel Permeation Chromatography (GPC), is a chromatographic method in which molecules are separated based on their size in solution relative to pore size of the column packing material. With proper choices of packing material, solvent, operating conditions, and careful calibration for a given polymer composition, SELC can be used to calculate molecular weight distribution. For determination of molecular weight distributions of vinylidene fluoride-based fluoroelastomers, a range of pore sizes of the packing (usually crosslinked polystyrene) must be used to cover molecular sizes corresponding to molecular weights of 103 to 107 daltons. Molecular size in solution is proportional to the product of molecular weight M and intrinsic viscosity [η]. For given operating conditions, elution time corresponds to a specific molecular size value of M [η]. A refractometer detector measures the relative concentrations of various polymer fractions in the column effluent. For calculation of molecular weight, a relationship between M and [η] must

be established by independent measurements. The Mark-Houwink equation is satisfactory for linear polymers: [η] = KMα. For fluoroelastomers dissolved in a given solvent at a set temperature, K and α vary considerably with copolymer composition, considerably complicating the calculation of molecular weight distribution and often causing significant errors in reported results. For branched polymers, a separate measurement of intrinsic viscosity [η] is necessary to allow molecular weight determination. Intrinsic viscosity may be measured on the whole polymer, or in modern SELC systems, on separated fractions by a second detector to measure effluent solution viscosity. Presence of branching leads to higher values of Mw and Mz. For low levels of branching, reproducibility of calculated results is often poor. See Molecular Weight Distribution, Branching, and Mark-Houwink Equation. Semibatch Polymerization – Polymerization system in which water, stabilizer, and monomer are charged initially to a reactor, followed by initiator addition at the desired reaction temperature, then by monomer feed at the rate at which polymerization proceeds. Other components, such as more initiator, chain transfer agents, and cure sites may also be added continuously or at intervals. No material is removed from the reactor until polymerization is complete. Semiconductor - A material whose electrical conductivity is intermediate between that of metals (conductors) and insulators (non-conductors) and can be modified physically or chemically to increase or decrease its conductivity from a “normal” state by “dopants.” Semicrystalline Plastic - A plastic (polymeric) material characterized by localized regions of crystallinity. See also Amorphous Polymer. Shear - Displacement of a plane of a solid body parallel to itself, relative to other parallel planes within the body; deformation resulting from this displacement. Shelf Life - Time during which a physical system such as material retains its storage stability under specified conditions. Also called storage life. Shore A - See Shore Hardness.

GLOSSARY Shore D - See Shore Hardness. Shore Hardness - Indentation hardness of a material as determined by the depth of an indentation made with an indentor of the Shore-type durometer. The scale reading on this durometer is from 0, corresponding to 0.100" depth, to 100 for zero depth. The Shore A indenter has a sharp point, is spring-loaded to 822 gf, and is used for softer plastics. The Shore D indenter has a blunt point, is spring-loaded to 10 lbf, and is used for harder plastics. Also called Shore A, Shore D.. Silane (SiH4) - A gas that readily decomposes into silicon and hydrogen, silane is often used to deposit silicon-containing compounds. It also reacts with ammonia to form silicon nitride, or with oxygen to form silicon dioxide. Silicon - A brownish crystalline semimetal used to make most semiconductor wafers. Silicon Dioxide (SiO2) - The silicon/oxygen film most often used for dielectric applications; can be deposited via silane or TEOS; often called “oxide.” Silicon Nitride (SiN2) - A silicon/nitrogen film dielectric deposited using plasma-enhanced or LPCVD. Silicon Wafer Production - The first step in semiconductor manufacturing begins with production of a wafer—a thin, round slice of a semiconductor material, usually silicon. In this process, purified polycrystalline silicon, created from sand, is heated to a molten liquid. A small piece of solid silicon (seed) is placed on the molten liquid, and as the seed is slowly pulled from the melt the liquid cools to form a single crystal ingot. The surface tension between the seed and molten silicon causes a small amount of the liquid to rise with the seed and cool. The crystal ingot is then ground to a uniform diameter and a diamond saw blade cuts the ingot into thin wafers. The wafer is processed through a series of machines, where it is ground smooth and chemically polished to a mirror-like luster. The wafers are then ready to be sent to the wafer fabrication area where they are used as the starting material for manufacturing integrated circuits.

339 Silicon Wafer Fabrication - The heart of semiconductor manufacturing is the wafer fabrication facility where the integrated circuit is formed in and on the wafer. The fabrication process, which takes place in a clean room, involves a series of principle steps described below. Typically it takes from 10 to 30 days to complete the fabrication process. Thermal Oxidation or Deposition - Wafers are pre-cleaned using high purity, low particle chemicals (important for high-yield products). The silicon wafers are heated and exposed to ultra-pure oxygen in the diffusion furnaces under carefully controlled conditions forming a silicon dioxide film of uniform thickness on the surface of the wafer. Masking - Masking is used to protect one area of the wafer while working on another. This process is referred to as photolithography or photo-masking. A photoresist or light-sensitive film is applied to the wafer, giving it characteristics similar to a piece of photographic paper. A photo aligner aligns the wafer to a mask and then projects an intense light through the mask and through a series of reducing lenses, exposing the photoresist with the mask pattern. Precise alignment of the wafer to the mask prior to exposure is critical. Most alignment tools are fully automatic. Etching - The wafer is then “developed” (the exposed photoresist is removed) and baked to harden the remaining photoresist pattern. It is then exposed to a chemical solution or plasma (gas discharge) so that areas not covered by the hardened photoresist are etched away. The photoresist is removed using additional chemicals or plasma and the wafer is inspected to ensure the image transfer from the mask to the top layer is correct. Doping - Atoms with one less electron than silicon (such as boron), or one more electron than silicon (such as phosphorous), are introduced into the area exposed by the etch process to alter the electrical character of the silicon. These areas are called P-type (boron) or N-type (phosphorous) to reflect their conducting characteristics. Repeating the Steps - The thermal oxidation, masking, etching and doping steps are repeated

340 several times until the last “front end” layer is completed (all active devices have been formed). Dielectric Deposition and Metallization - Following completion of the “front end,” the individual devices are interconnected using a series of metal depositions and patterning steps of dielectric films (insulators). Current semiconductor fabrication includes as many as three metal layers separated by dielectric layers. Passivation - After the last metal layer is patterned, a final dielectric layer (passivation) is deposited to protect the circuit from damage and contamination. Openings are etched in this film to allow access to the top layer of metal by electrical probes and wire bonds. Electrical Test - An automatic, computerdriven electrical test system that checks the functionality of each chip on the wafer. Chips that do not pass the test are marked with ink for rejection. Assembly - A diamond saw typically slices the wafer into single chips. The inked chips are discarded, and the remaining chips are visually inspected under a microscope before packaging. The chip is then assembled into a package that provides the contact leads for the chip. A wirebonding machine then attaches wires, a fraction of the width of a human hair, to the leads of the package. Encapsulated with a plastic coating for protection, the chip is tested again prior to delivery to the customer. Alternatively, the chip is assembled in a ceramic package for certain military applications. Silicide - A film compound of silicon with a refractory metal. Common silicide semiconductor films (used as interconnects) include tantalum, tungsten, titanium, and molybdenum. Silicone - Silicones are polymers, the backbone of which consists of alternating silicon and oxygen atoms. Pendant organic groups are attached to the silicon atoms. They are usually made by hydrolyzing chlorosilanes, followed by polycondensation and crosslinking. Depending on the degree of crosslinking and the nature of pendant groups, silicones can be liquid, elastomeric, or rigid. Liquid silicones or silicone fluids such as dimethylsiloxane have very good

FLUOROELASTOMERS HANDBOOK antiadhesive properties, lubricity, resistance to heat and chemicals, and are used as release agents, surfactants, and lubricants in plastics. As lubricants, they improve wear resistance of plastics. Silicone elastomers have high adhesion, resistance to compression set, flexibility, good dielectric properties, weatherability, low flammability, good moisture barrier properties, and thermal stability, but somewhat low strength. Optically clear grades are available. Fluorosilicones contain 3,3,3-trifluoropropyl pendant groups in place of about half the methyl groups attached to the polymer backbone. Fluorosilicones have better fluid resistance and thermal stability than silicones, and have better low-temperature flexibility than fluorocarbon elastomers. Silicones and fluorosilicones are processed by coating and injection molding. They are used as optical fiber coatings, electronic connector encapsulants, printed circuit board coatings, seals, diaphragms, fabric coatings, medical products, adhesives, sealants, and glazing compounds. Rigid silicone resins offer good flexibility, weatherability, dirt release properties, dimensional stability, and are stronger and harder than silicone rubbers. The resins are attacked by halogenated solvents. They are processed by coating, casting, injection molding, compression molding, and transfer molding. Silicone resins are used as coatings, adhesives, sealants, bonding agents, and molded parts. Also called siloxane, polysiloxane, silicone fluid, silicone rubber, silicone plastic, VMQ, and FVMQ. Sliding Velocity - The relative speed of movement of one body against the surface of another body (counterbody) without the loss of contact as in a sliding motion during wear and friction testing of materials. In the sliding motion, the velocity vectors of the body and the counterbody remain parallel and should be unequal if they have the same direction. Slitting - This is a process to cut film and webs into narrower width than the starting material. A roll of the wide film is unwound and passed over sharp knives positioned to obtain the required cut widths. The narrower films are wound up on separate cores. Special machines are available for slitting films.

GLOSSARY

341

Sodium Etching - Sodium etching is a process by which the surface of fluoropolymers is rendered adherable. During etching the fluoropolymer surface is brought into contact with a sodium solution (1:1) in naphthalene dissolved in tetrahydrofuran or an anhydrous solution of sodium in liquid ammonia. Sodium Naphthalenide - See Sodium Etching. Softening Point - Temperature at which the material changes from rigid to soft or exhibits a sudden and substantial decrease in hardness. Solubility - The solubility of a substance is the maximum concentration of a compound in a binary mixture at a given temperature forming a homogeneous solution. Also called dissolving capacity. Solubility Parameter - Solubility parameter characterizes the capacity of a substance to be dissolved in another substance (e.g., of a polymer in a solvent). It represents the cohesive energy of molecules in a substance and determines the magnitude and the sign of the heat of mixing two substances in given concentrations. The magnitude and the sign of the heat of mixing determine the sign of the free energy of mixing. The solution occurs when the sign of the free energy of mixing is negative. Solution Viscosity - High-viscosity concentrated fluoroelastomer solutions are used for a few coatings applications. However, viscosity of dilute solutions is much used as a measure of fluoroelastomer molecular weight and for monitoring and controlling polymerization process conditions. Polymer concentration in solution must be low enough to avoid significant interaction between chains, so that solution viscosity reflects contributions of individual macromolecules. For vinylidene fluoride-based fluoroelastomers, typical viscosity measurements may be made on solutions with approximate concentration c = 0.1 g/dL at 30°C, using a capillary viscometer. Important viscosity parameters are described below. Relative viscosity ηr is the ratio of viscosity of a polymer solution to that of the base solvent, typically determined from the ratio of capillary viscometer efflux times: ηr = tsolution/tsolvent

Inherent viscosity ηinh or logarithmic viscosity number, usually calculated from relative viscosity determined at concentration c = 0.1 g/dL at 30ºC, is defined by: ηinh = (ln ηr)/c Intrinsic viscosity [η] or limiting viscosity number is defined as the limit of inherent viscosity as polymer concentration is reduced to zero: [η] = lim (ln ηr)/c c→0

Intrinsic viscosity is related to molecular weight by the Mark-Houwink equation, used for SELC calibration for determination of molecular weight distribution. Ordinarily, inherent viscosity is only slightly lower than intrinsic viscosity. Thus, inherent viscosity is most often used for monitoring polymer characteristics during production. See Mark-Houwink Equation, SELC, and Molecular Weight Distribution. Spherulite - In plastics, a rounded aggregate of radiating lamellar crystals with amorphous material between the crystals. Has the appearance of a pom-pom. Spherulites exist in most crystalline plastics and usually impinge on one another to form polyhedrons. Range in size from a few tenths of a micron in diameter to several millimeters. Steric Hindrance - A spatial arrangement of the atoms of a molecule that blocks reaction of the molecule with another molecule. Stick Slip - This is a jerking action that occurs in a moving part such as a bearing in overcoming a higher static coefficient of friction than a dynamic coefficient of friction before movement begins. Strain - The per unit change, due to force, in the size or shape of a body referred to its original size or shape. Note: Strain is nondimensional but is often expressed in unit of length per unit of length or percent. Also called mechanical strain. See also Flexural Strain, Compressive Strain, Tensile Strain. Stress Cracking - Appearance of external and/or internal cracks in the material as a result of stress that is lower than its short-term strength. See also Environmental Stress Cracking.

342 Stress Relaxation - Time-dependent decrease in stress in a solid material as a result of changes in internal or external conditions. Also called stress decrease. Substrate - A wafer that is the basis for subsequent processing operations in the fabrication of semiconductor devices. Supercritical Carbon Dioxide - Refers to carbon dioxide that has been heated to above its critical temperature and pressure. Supercritical CO2 is a potent solvent for great many organic substances. It is also a suitable medium for polymerization of fluorinated monomers. Surface Energy - See Surface Tension. Surface Roughening - In adhesive bonding, a commonly used surface preparation technique in which the substrate surface is mechanically abraded. The roughened surface increases bondability by dramatically increasing the number of sites available for mechanical interlocking. Surface Roughness - The closely spaced unevenness of a solid surface (pits and projections); can be quantified by various methods (e.g., by using a profilometer in coatings).

FLUOROELASTOMERS HANDBOOK elastomers and thermoplastics with low crystallinity, monomers and oil-soluble initiator are dissolved in the polymer particles, so that bulk polymerization kinetics apply. With some highly crystalline fluoroplastics, little or no monomer is dissolved in particles and a water-soluble initiator is used, so polymerization occurs mainly at or near particle surfaces. An advantage of suspension polymerization is high purity of the polymer product compared to that made by emulsion polymerization.

T Talc - Talc is a filler made by dry or wet grinding of mineral magnesium silicate. Talc improves stiffness, dimensional stability, flexural modulus, creep resistance, flow, surface smoothness, moisture resistance, tensile strength, and wear resistance of plastics. It also increases heat deflection temperature and decreases vapor permeability. Can be used as a film antiblock agent. Used mainly in polypropylene but also in thermoplastic and unsaturated polyesters and epoxy resins at low levels. Surface-modified grades are available.

Surface Tension - The surface tension is the cohesive force at a liquid surface measured as a force per unit length along the surface or the work which must be done to extend the area of a surface by a unit area (e.g., by a square centimeter). Also called free surface energy.

Tempering - Homogeneous tempering refers to minimization of the mold surface temperature between the inlet and outlet of the cooling fluid. Wall temperature differences could cause warping of the part.

Surfactant - Derived from surface active agent. Defined as substances which aggregate or absorb at the surfaces and interfaces of materials and change their properties. These agents are used to compatibilize two or more immiscible phases such as water and oil. In general, one end of a surfactant is water soluble and the other end is soluble in an organic liquid.

Tensile Fatigue - Progressive localized permanent structural change occurring in a material subjected to cyclic tensile stress that may culminate in cracks or complete fracture after a sufficient number of cycles. See also Fatigue, Flexural Fatigue.

Suspension Polymerization - Refers to a heterogeneous polymerization regime in which the product is a suspension of relatively large polymer particles in the liquid medium (usually water) of the reaction. Little or no surfactant is added to the aqueous phase. Particles are usually stabilized by addition of a small amount of water-soluble gum and by relatively high agitation rate. In suspension polymerization of

Tensile Elongation - See Elongation.

Tensile Heat Distortion Temperature - See Heat Deflection Temperature. Tensile Properties - Properties describing the reaction of physical systems to tensile stress and strain. Tensile Strain - The relative length deformation exhibited by a specimen subjected to tensile force. See also Flexural Strain, Strain. Tensile Strength - The maximum tensile stress that a specimen can sustain in a test carried to

GLOSSARY failure. Note: The maximum stress can be measured at or after the failure or reached before the fracture, depending on the viscoelastic behavior of the material. Also called ultimate tensile strength, tensile ultimate strength, tensile strength at break. Tensile Strength at Break - The maximum load per original minimum cross-sectional area of the plastic specimen in tension within the gauge length when the maximum load corresponds to the break point. Measured according to ASTM D638. See also Tensile Strength. Tensile Strength at Yield - The maximum load per original minimum cross-sectional area of the plastic specimen in tension within the gauge length, when the maximum load corresponds to the yield point. Measured according to ASTM D638. Tensile Stress - The force related to the smallest original cross-section of the specimen at any time of the test. Termination - In free radical polymerization, a free radical is terminated by reaction with another free radical to form a neutral molecule. This is usually a very fast reaction which occurs quickly when radicals come into close proximity. In fluoroelastomer polymerization, termination by reaction of two chain radicals usually results in combination to form a dead chain with molecular weight equal to the sum of that of the chain radicals. In many heterogeneous polymerization systems, mobility of long-chain radicals is low, so most termination of long chains occurs by reaction with small, mobile radicals. Thermal Conductivity - The time rate of heat transfer by conduction across a unit area of substance at unit thickness and unit temperature gradient. Thermal Expansion Coefficient - The change in volume per unit volume resulting from a change in temperature of the material. The mean coefficient of thermal expansion is commonly referenced to room temperature. Thermal Properties - Properties related to the effects of heat on physical systems such as materials and heat transport. The effects of heat

343 include the effects on structure, geometry, performance, aging, stress-strain behavior, etc. Thermal Recycling - A plastics recycling method in which mixed plastic waste undergoes controlled combustion, producing heat that can be used as a substitute for oil, gas, and coal or for the generation of energy at power plants. Thermal Stability - The resistance of a physical system such as material to decomposition, deterioration of properties, or any type of degradation in storage under specified conditions. Also called oven stability, heat stability. Thermoforming - The process of heating a thermoplastic sheet to a point at which it softens and flows, then applying differential pressure to make the sheet conform to the shape of a mold or die. Thermoplastic - Thermoplastics are resin or plastic compounds which, after final processing, are capable of being repeatedly softened by heating and hardened by cooling by means of physical changes. There are a large number of thermoplastic polymers belonging to various classes such as polyolefins and polyamides. Also called thermoplastic resin. Thermoplastic Elastomer – A polymer, usually a block or graft copolymer, containing a major fraction of amorphous chains with low glass transition temperature to impart elastomeric properties, and also a fraction of glassy or crystalline polymer chains which serve as tie points to maintain the shape of the matrix. Thermoplastic elastomers may be processed and molded into parts by usual thermoplastic handling techniques. They behave as elastomers after molding or extrusion, but, unlike thermosetting elastomers, they can be reprocessed by melting and remolding. Commercial thermoplastic fluoroelastomers are A-B-A block polymers with a central elastomeric block (B) attached to shorter crystallizable plastic chain segments (A). Thermoplastic Resin - See Thermoplastic. Thermoset - Thermosets are resin and plastic compounds which, after final processing, are substantially infusible and insoluble. Thermosets are often liquids at some stage in their manufacture or processing and are cured by

344 heat, oxidation, radiation, or other means often in the presence of curing agents and catalysts. Curing proceeds via polymerization and/ or cross-linking. Cured thermosets cannot be resoftened by heat. There are a large number of thermosetting polymers belonging to various classes such as alkyd and phenolic resins. Also called thermosetting resin, thermoset resin. Thermoset Resin - See Thermoset. Thermosetting Elastomer - A large class of essentially amorphous polymers with low glass transition temperatures; vulcanizates of these polymers can be stretched at room temperature to at least twice their original length and, after having been stretched and the stress removed, return with force to approximately their original length in a short time. To attain these elastic properties, the elastomers must be crosslinked or vulcanized into a network, usually by heating in the presence of various crosslinking agents and accelerators. There are natural and synthetic rubbers. The most important synthetic rubber families are olefin rubbers, diene rubbers (nitrile, butadiene, neoprene), silicone rubbers, urethane rubbers, and fluoroelastomers. TR-10 - In a low-temperature retraction test, the temperature at which a cured elastomer specimen recovers 10% of the tensile strain imposed before cooling to a very low temperature, then releasing the stress and heating while observing recovery. For a fluoroelastomer vulcanizate with medium hardness, TR-10 is close to the glass transition temperature of the base fluoroelastomer. Transfer - In free radical polymerization, a reaction which involves reaction of an active moiety with a free radical to cap off growth of that radical while transferring radical activity to the residue of the transfer agent. Many types of transfer reactions may occur, including transfer to an active chain transfer agent, monomer, polymer, or adventitious impurity. Typical transfer agents useful in controlling molecular weight in emulsion polymerization of vinylidene fluoride-based fluoroelastomers are low molecular weight alcohols, esters, and ketones. These are soluble in both water and polymer particle phases, and react with free radicals by

FLUOROELASTOMERS HANDBOOK transferring active H atoms on C atoms adjacent to hydroxyl or carbonyl groups. The resulting O-containing transfer radicals are reactive to subsequent propagation of new chains. Iodo or bromo alkanes and fluoroalkanes are also active as transfer agents. Long-chain hydrocarbons are less active toward transfer and subsequent propagation, but may be useful in slower polymerizing systems such as perfluoroelastomer or tetrafluoroethylene/propylene polymerization. Cyclic alkanes and aromatics undergo transfer, but the resulting radicals are so unreactive that these materials act as inhibitors in fluoromonomers polymerization. Transfer Molding - An elastomer molding process in which uncured compound is placed in a pot and then forced through a sprue into the mold by a plunger. The mold is kept closed for curing; the plunger is then raised, and transfer pad material is removed and discarded. The mold is opened for removal of the part; flash and sprue material is trimmed and discarded. Triallyl isocyanurate (TAIC) - Multifunctional trap used as crosslinking agent for free radical curing of fluoroelastomers. See also Peroxide Cure. Tribological Characteristics - These characteristics deal with friction or contact related phenomenon in materials. Coefficient of friction and wear rate are the most important tribological characteristics of a material. A block polymers with a central elastomeric block (B) attached to shorter crystallizable plastic chain segments (A). Two-Roll Mill - See also Milling.

U Ultraviolet Light - See Ultraviolet Radiation. Ultraviolet Radiation - Electromagnetic radiation in the 40– 400 nm wavelength region. Sun is the main natural source of UV radiation on the earth. Artificial sources are many, including fluorescent UV lamps. Ultraviolet radiation causes polymer photodegradation and other chemical reactions. Note: UV light comprises a significant portion of the natural sun light. Also

GLOSSARY

345

called UV radiation, UV light, ultraviolet light. See also Ultraviolet Radiation Exposure. Ultraviolet Radiation Exposure - In adhesive bonding, a surface preparation technique in which the substrate is irradiated with high intensity UV light. Exposure to UV radiation results in chain scissions, cross-linking, and oxidation of the polymer surface. The effectiveness of this technique is dependent on the wavelength of radiation used. It is commonly used for polyolefins. Also called UV exposure.

V Vacuum Forming - Vacuum forming is a type of thermoforming process consisting of preheating the plastic sheet prior to forming. The sheet is formed into the female mold by application of vacuum through holes in the mold. van der Waals Attraction - See van der Waals Forces. van der Waals Forces - Weak attractive forces between molecules, weaker than hydrogen bonds and much weaker than covalent bonds. VDF - See Vinylidene Fluoride. Vinyl Chloride (VC) - Monomer for polyvinylchloride, CH2=CHCl. Vinyl Fluoride (VF) - Monomer for polyvinylfluoride, CH2=CHF. Vinylidene Fluoride (VDF) - Monomer for polyvinylidene fluoride thermoplastics and major monomer for a number of fluoroelastomer compositions, CH2=CF2. Vinylidene Fluoride/Hexafluoropropylene Copolymer - Copolymers of vinylidene fluoride with less than 25 wt % hexafluoropropylene are crystalline thermoplastics. These have good thermal stability; antistick, dielectric, and antifriction properties; and good thermal resistance. Mechanical strength and creep resistance are somewhat poorer than other fluoroplastics. Processing by conventional thermoplastic techniques is difficult due to its high melt viscosity. Uses include chemical apparatus, containers, films, and coatings.

Copolymers of vinylidene fluoride with about 40 weight % hexafluoropropylene are amorphous elastomers which can be cured with diamines or bisphenols to form seals and other parts which are resistant to most fluids and retain useful properties in long-term service up to about 250°C. Copolymers with this composition comprise the largest family of fluorocarbon elastomers. Vinylidene Fluoride/Hexafluoropropylene / Tetrafluoroethylene Terpolymer - A family of fluorocarbon elastomers, generally with high fluorine content than vinylidene fluoride / hexafluoropropylene copolymers. Depending on composition, the terpolymers have enhanced fluid resistance and heat stability compared to dipolymers. Terpolymers are used in seals, diaphragms, tubing, and a variety of molded parts, especially for use in automotive fuel and power train systems. Viscosity - The internal resistance to flow exhibited by a fluid, the ratio of shearing stress to rate of shear. A viscosity of one poise is equal to a force of one dyne/square centimeter that causes two parallel liquid surfaces one square centimeter in area and one centimeter apart to move past one another at a velocity of one cm/ second. Viscoelasticity - A property of a material that exhibits both elastic and viscous behavior. Viscoelastic materials have both solid-like characteristics – elasticity, strength, and stability of form – and liquid-like characteristics, such as flow that depends on time, temperature, and stress. All elastomers and some plastics exhibit viscoelasticity. Voids - See Porosity.

W Wafer - The thin, circular slice of pure silicon on which semiconductors are built. The largest wafer in current use is 200 mm (8-inch) diameter, with 300 mm wafers emerging as the next wafer size. Up to 200 individual semiconductor devices, or “chips,” can be fabricated on each wafer, depending on the chip and wafer size. Warpage - See Warping.

346 Warping - Dimensional distortion or deviation from the intended shape of a plastic or rubber article as a result of non-uniform internal stress (e.g., caused by uneven heat shrinkage). Also called warpage. Wear - Deterioration of a surface due to material removal caused by any of various physical processes, mainly friction against another body. Wear Rate - See Tribological Characteristics. Welding - A method for joining fluoroelastomer parts using a thermoplastic fluoropolymer which is placed between fluoroelastomer surfaces, melted, then cooled to effect the weld. This method is used for splicing together cured fluoroelastomer cord sections to form large O-ring seals. The parts are clamped together and the joint is heated with a heater band. Weld Strength - Strength of a welded plastic part at a seam that has been welded is called weld strength. It is measured by methods similar to those for measuring the strength of adhesive bonds. See also Adhesive Bond Strength. Wettability - The rate at which a substance (particle, fiber) can be made wet under specified conditions. See also Wetting. Wetting - The spreading out (and sometimes absorption) of a fluid onto (or into) a surface. In adhesive bonding, wetting occurs when the

FLUOROELASTOMERS HANDBOOK surface tension of the liquid adhesive is lower than the critical surface tension of the substrates being bonded. Good surface wetting is essential for high strength adhesive bonds; poor wetting is evident when the liquid beads up on the part surface. Wetting can be increased by preparation of the part surface prior to adhesive bonding.

Y Yellowing - Developing of yellow color in nearwhite or near-transparent materials such as plastics or coatings as a result of degradation on exposure to light, heat aging, weathering, etc. Usually is measured in terms of yellow index. Yield Deformation - The stain at which the elastic behavior begins, while the plastic is being strained. Deformation beyond the yield is not reversible. Young’s Modulus of Elasticity - In the elastic region, the relationship between stress and strain of a polymer, undergoing tensile or compressional strain, is linear (Hooke’s Law). In this relationship, stress is proportional to strain. The coefficient of proportionality in this stressstrain relationship is called Young’s Modulus of Elasticity.

Trademarks Trademark

Property of

Trademark

Property of

Aflas®

Asahi Glass Co.

MDR 1000™

Monsanto Monsanto

Chemraz®

Greene, Tweed & Co.

MDR 2000™

Dai-el®

Daikin Corp.

Spectrum™

DuPont Co.

DuPont™

DuPont Co.

Tecnoflon®

Solvay Solexis DuPont Co.

Dyneon™

3M Co.

Teflon®

Elastomag®

Rohm and Haas

Tefzel®

DuPont Co.

ETP-600S™

DuPont Co.

Tyvek®

DuPont Co.

Fluorel®

3M Co.

Viton®

DuPont Co.

DuPont Co.

Viton GLT®

DuPont Co.

Kalrez®

Index

Index terms

Links

Index terms Analysis methods

A

Links 15

Applications

Accelerators phosphonium quaternary phosphonium salt Accumulator Acetone

78

83

253

aeronautical

8

automotive

103 55

57

111

organic and inorganic

Additives engine oils

chemical processing

197

seals semiconductor fabrication industry

293

Aqueous brine

Addition reactions tetrafluoroethylene

296

pharmaceutical industry

291

Acrylic rubbers oil seals

automotive transmission

of perfluoroelastomers

Acrylic elastomers seals

291

oil fields

196

9 6

237 50

292

Aqueous phase termination

46

Aromatic dihydroxy compounds

78

Adhesive systems

292

Autoclave curing

Adiabatic reactor

52

3 283

Automotive

Aeration 293

126

fuel system requirements

279

fuel tanks

287

196

Air entrapment

117

lubricants

78

85

shaft seals

241

Alkylphenol amines engine oil additives Amine-free radical inhibitors

292

197

fluids service

Aeronautical applications Aliphatic peroxides

196

197

Aqueous phase oligomerization rates

ASTM classification

19

3

305

292

308

197

47

to metal inserts

11

197

Aqueous oligomeric radical growth

27

Adhesion

effect on oil seals

3

automotive power train

of fluoroelastomers

Acids

197

Automotive seals

291

Automotive shaft seals

295

87

B

Amines engine oil additives

292

oil-soluble

237

water-soluble

237

Backbone perfluoroelastomer

8

Backrinding

112

Amino phosphinic derivatives

83

Banbury mixer

105

Aminosilane-coated wollastonite

90

Barwell Precision Preformer

110

Amorphous elastomer compounds

280

Base-resistant fluoroelastomers

32

349

350

Index terms Base-resistant product

Links

Index terms

96

Bases organic and inorganic Benzyltriphenylphosphonium chloride Bifluoride

196 250 79

Links

excessive

33

Breaker plate

108

Brittle point

17

Bromine cure sites

18

Bromine-containing cure-site monomers

90 85

Bimodal blends

105

Bromine-containing fluoroelastomers

Bimodal polymers

287

Bromine-containing monomers

Biocides

119

Bromine-containing olefins

32

BTFB monomer

33

2,2’-Bis(t-butylperoxy)diisopropylbenzene

83

C

Bisphenol

77

Ca(OH)2/MgO ratio

bulk systems

82

Calcium hydroxide level

commercial

82

precompounds

adhesion effect

16 78 111

32 79 195

253

283

vulcanizates

82

Bisphenol AF

8

Bisphenol curing

293

Bisphenol precompounds

294

Bisphenol-containing precompounds

295

dipolymers

287

gums

299

polymers

125

precompounds

282

terpolymers

287

VDF/HFP

110

61 110 227

249 292

Calendering

117

Carbon black levels

246

Carbon dioxide environment

197

299

Carbonyl fluoride for synthesis of PMVE

250

Bisphenol-curable

Bisphenol-curable gums

9

227

Bis(triarylphosphin)iminium salts

curing

8

110

282

Caulks

31 304

Chain branching

59

Chain-transfer agents

37

55

Charging

57

59

Chemical attack by additives

294

Chemical processing applications 288

294

Chemical resistance engine seals

295

vulcanizates

195

Chlorotrifluoroethylene

Bisphenol-cured

copolymers

compounds

6

fluoroelastomers

3

79

Bisphenol-cured elastomers

291

292

Bisphenol-cured terpolymers

294

Black compounds

245

Blisters

112

Branching

254

196

6 7

Clamp unit

114

Coagulants

38

Coal-fired power plants

299

Coatings latex

303

Coefficient of linear expansion

196

Cold feed extruder

108

197

58

351

Index terms

Links

Index terms

Combustion products from fluoroelastomer compounds Commercial elastomeric products Commercial fluorocarbon elastomers Commercial fluoroelastomers

Copolymers 308 16

elastomeric

234

TFE-propylene

227

VDF/HFP

5

vinylidene fluoride

37

Counter-rotating rolls

Components addition of

Links

78 7 104

Cracking products

57

tetrafluoroethylene

Composition

29

determination of

15

Creaming

119

determines characteristics

13

Creep

304

Compounding

99

Compression

260

241

Critical length

45

Critical micelle concentration (cmc)

45

Cross linking agent

Compression molding advantages

111

radical trap

196

disadvantages

111

Cross-head die

108

shaft seals

291

Crosslinker

250

Compression set

246

250

resistance

254

288

tests

243

245

Bisphenol AF 289

288

reactions

86

temperatures

77

245

Crosslinks

Computer-controlled mixing lines

105

Crystalline aluminosilicates

Continuous emulsion polymerization process

79

Crystalline plastics

243 90 304

Crystallinity 40 47 50

43 48

Continuous reactor control of

52

design and operation

50

operation

37

51

49

50

Continuous stirred tank reactors (CSTR)

280

103

Crosslinking

Compression stress relaxation measurements Conjugated diene structure

303

44 49

affected by monomers CSTR

117

Cooling jackets

51

54

Copolymer composition relationship

39

41

Copolymerization

39

with ethylene

15

with propylene

15

54

monomer feeds

51

polymerization systems

52

shutdown

51

startup procedures

51

steady states polymerization systems

52

CTFE-based plastics

Control systems

13

7

Curative masterbatches

250

Curatives

106

dispersion of Cure characteristics Cure kinetics Cure rates Cure-site monomers

103 295 77 253 32 61

37

59

352

Index terms Cure sites

Links 6

8

Index terms 17

Difluoroacetamides

Links 27

monomers

32

Diiodide transfer

perfluorophenyl

18

Dimethylacetamide

79

Dipolymer compositions

14

Cure systems bisphenol characteristics

195

119

Dipolymers

77

commercial

82

peroxide

195

curing of

250

Cure times

250

gums

250

Cured stock

111

heat-treated TFE/P

Curing characteristics

14 20

fluoroelastomers

32

by irradiation peroxide systems

TFE/P

260

ETP

VDF/HFP

96 227 77

engine oil additives

292

Dispersion

systems

8

stability

51

Cyano FVE

33

stabilizer

44

Cyclic amidine base

82

volume

56

Disposal of fluoroelastomers

D

308

Divinylperfluoroalkane 304

®

260

Dai-el LT-303

crosslinks DLVO model of colloid science

Decomposition rate first order Dehydrofluorination Demolding

52 79

234

254

Detergents engine oil additives Deuterated tetrahydrofuran solution

98 106

Diamine

119

Diamine cure system

77

254

DuPont Dow Vertex™ seal

304

Dust lips

291

Dynamar™ Polymer Processing Additives

304

Dyneon FC 2210X

304

Dyneon® Fluoroelastomer FX 10180

303

®

Dyneon precompounds 78

properties of

282

®

304

Dyneon THV fluorothermoplastic

304

Die entrance

305

E

Die-cut gaskets

245

E/TFE/PMVE elastomers

Diels-Alder adducts

29

Elastomeric behavior

Dienic phenyl ether crosslinks

82

Elastomeric seals

Dienone

82

Elastomers

15

46 106

Die coating

Differential scanning calorimetry (DSC)

196

Drying extruder

®

292

Dewatering

104

Dispersants

14

Dai-el G-101

282

303

304

®

15

20 5 260

cure systems

77

definition

15

53

106

353

Index terms

Links

Index terms

Elastomers (Continued)

Links

elastomers

100

ethylene acrylic

304

fluid resistance

236

ETP

100

fluoroelastomers

237

extrusion

114

vulcanizates

100

fluorinated thermoplastic

303

Exothermic decomposition

308

pellets

106

Expansion joints

299

synthetic

103

elastomeric

299

VDF/HFP/TFE

253

flue duct

241

Elastoplastics Elongation at break Embrittlement Emissions Emulsion polymerization

254

16

Explosion hazards

250

tetrafluoroethylene

307 27

78

288

Explosion potential

288

289

Explosive decompression

197

41

42

Exposure to severe environments

237

44

34

free-radical

37

Extruder barrels

108

soapless

47

Extrusion

241

Extrusion characteristics

287

End groups iodine

59

ionic

52

sulfonate

43

53

78

Engine oil additives Engineering controls for engine seals

Feed zone

108

307

FEPM elastomers

295

Fick’s Laws

280

Filler neck hose

288

Filler system

279

Fillers

245

Fires during post curing

308

295 197

in deep wells

197

fluid

260

harsh

196

temperature

260

Epichlorohydrin

282

Fissures seals FKM shaft seals

90 15

flammability

34

properties

32

curing

291 293

Flammability

copolymerization

ETP

89

FKM elastomers

Ethylene

Ethylene/TFE/PMVE

241 108

aggressive

tetrapolymer

Fabrication Feed section

Environments

Epoxysilane

F

292

Environmental conditions

6 99 237 20

227

236

236

ethylene and propylene

32

hazards

34

Flash

111

Flexible fuels

289

Flexural modulus

304

Flow characteristics

254

Flue duct expansion joints

241

283

237

354

Index terms

Links

Index terms

Links

Flue duct system

299

thermoplastic

119

Flue gases

299

VDF-based FKM

227

Fluid resistance

6 100

HK classification vulcanizates

8

9

3 195

VDF/HFP VDF/HFP/TFE

243

VDF/PMVE/TFE

289

veneer stock

283

Fluorinated matrix

77

without ionic end groups

Fluorinated monomers

25

worldwide production

Fluorinated vinyl ethers

33

Fluorine content affects chemical resistance

14 253 19

varying

14

254

60 3

Fluoromonomers 15

16

toxicity

33

Fluoroplastics production volumes

294

TFE/P elastomers

77

25

Fluoropolymers melt-processible

107

7

processing

305

Fluorocarbon elastomers

13

Fluorosilicone

Fluorocarbons

41

Fouling

87

Fluoroelastomers

13

Fourier Transform Infrared (FTIR)

15

applications

9

Free radicals

83

288

6

8

14

37

38

Fluoroalkoxyphosphazene

base-resistant thermoplastic

120

bisphenol-curable

282

characteristics

32 polymerization

77

components

279

compounding

103

copolymerization

curing

7

9

Fuel

15

compositions

279

emission limits

287

gums

303

methanol-containing

282

high-fluorine

260

oxygenated

279

partially oxidized

280

incorporated iodine units

59

latex

119

low-viscosity

303

o-rings

Fuel hose 304

279

additional layers of

282

279

estimation of M15 fuel loss

282

operating conditions

114

veneer

287

peroxide-curable

243

PMVE-containing

289

polymerization processing methods used

42 103

producers

11

sales

13

for seals setting and controlling TFE-olefin

291 48 227

254

Fuel injector o-rings

288

Fuel permeability

281

Fuel pump

279

seals

288

Fuel sender module

287

Fuel swell measurements

289

Fuel tank components

279

280

355

Index terms

Links

Full (black) compounds

245

Furnace blacks

246

Index terms Heat of reaction TFE deflagration Heat resistance

FVE cyano FVMQ o-rings

HK classification

33

Heats of fusion

288

Helix angle

G Gas deposition processes Gaskets cured-in-place Gates Gelation Glass transition temperature

Links 29 195 3 15 108

Hexafluoropropylene

13

in fluoroelastomers

25

10

properties

29

304

synthesis

29

197

Hexamethylene diamine

116

HFP-based fluoroelastomers

82 5

6

9

77 7

HFP-containing fluoroelastomers adequate seal performance

289

E/TFE/PMVE

20

fluoroelastomers

10

HFP-containing polymers

293

Green strength

250

High-fluorine elastomers

289

Grit-blasting

292

High-fluorine product

260

Grooves in seals Gum fluoroelastomers Gum polymer VDF/HFP/TFE

High-VDF elastomers 19

chemical resistance

104

Halogenated vinyl monomers

properties

38 253

6

288

oil seals

293

seals

291

Hoses automobile fuel

307

Handling procedures 34

Hard chrome plating

111

Hazardous monomer mixtures

o-rings

Homogeneous nucleation

32

fluoromonomers

3

HNBR

Handling precautions fluoroelastomers

296

HK classification

H Halogen cure site

30

34

Hazards

45

46

241 60

Hydraulic clamp

114

Hydrocarbon fuel mixtures

279

Hydrocarbon swell

227

Hydrocarbon thermoplastics

304

287

Hydrocarbons

explosion

54

safety

52

56

resistance to Hydrogen sulfide

Heat

environment

exchange limits

56

of polymerization

50

removal of

51

13

Hydropentafluoropropylene 52

56

197 90

Hydroperoxides

288

Hydroxides

103

20

356

Index terms

Links

Index terms

I

Links

L

Ignition sources Immersion testing Initiation

34

Latex processing

293 43

303

Lips seals

45

291

by thermal decomposition

49

Liquid feeds

51

constant rate

58

"Living radical" polymerization

93

Initiator

37

decomposition

86

molar feed rate of

53

Injection molding

78

55

57

113

Loading fixtures

112

Low-fluorine polymers

294

Low-pressure extrusion

304

Low-temperature characteristics

machinery

114

Low-temperature flexibility

shaft seals

291

Lube oils

troubleshooting

117

Injection unit

114

Inorganic acids

196

Inorganic backbones

196

Intermeshing rotors

105

Intrinsic viscosity

48

Iodine cure sites

18

Iodine groups Iodine-containing transfer agents

8

M15 fuel loss estimation adhesion effect 9

59

125

281 282 292

Maintenance procedures

307

Mandrel

280

Masterbatches

250

196

Material Safety Data Sheets

307

Melt fracture

305

Melt-processible fluoropolymers

107

Melting endotherm

303

33 58

Melting points

FTPE

304

Isobutene

111

of elastomers THV Metal oxides Metering zone

Jamak stress relaxation jigs

288

Jigs

243

245

245

K Kinetic analysis

38

Kinetic models

47

15

Melting temperature

33

J

Shawbury-Wallace

19

294

Irradiation curing

ITFB monomers

6

Magnesium oxide level

Ionic end-group level. See end groups optimizing

17

M

7

Inorganic bases

Iodine end groups

amine additives

14

48

53

304 90 108

Methyl bromide

86

Methyl radicals

86

Methyltributylammonium Bisphenol AF salt

96

Micellar entry

45

mechanism

46

Microemulsion process Mineral fillers

103 111

59 100

249

20

357

Index terms

Links

Index terms

Mixed stock

107

Nonionic radical

Modulus

250

Nozzle flash

Mold

Links 43 117

Nuclear magnetic resonance (NMR)

15 90

79

cavities

110

Nucleophiles

closing

117

Nucleophilic attack

designs

117

Nucleophilic diamine

77

flash

117

Nylon

12

fouling

111

opening

117

O

platens

111

O-ring compounds

243

precision extruded shapes

241

O-ring seals

110

3 288

10

release sticking

87

O-rings

287

289

Molded composite parts

249

specifications

Molding 241

injection

241

of shaft seals

291

temperatures

77

Molecular sieve zeolites

cracking product

Monitoring systems Monomer

cracking product ODR modulus

241

44 37

charge

59

combinations

5

compositions

50

concentration

47

CSTR feeds

51

fugacity

48

gaseous

51

recovery and recycle

49

57

Oil resistance

295

Oil seals

291

testing

293

hydrogenated

281

Nitrogen leakage

289

32

Operating procedures

307

Organic acids and bases

196

Oscillating disk rheometry

197

34

78

Oxidizing agents resistance to

196

P Particles

77

13

85 196

Olefin monomers

N Nitrile rubber

29

applications

307 13

29

Oil fields

90

affect on characteristics

MT black

243

Octafluoroisobutylene

Molecular weights controlling

282

Octafluorocyclobutane

compression

transfer

234

281

by secondary nucleation

47

determining number

48

determining number of

44

entry into

45

formation

47

formation and growth

44

55

241

358

Index terms

Links

Index terms

Particles (Continued)

Peroxide-cured vulcanizates

formation by homogeneous nucleation

45

Peroxides

micellar entry mechanism

46

Persulfate-sulfite redox initiation

polymerization rate

47

precursor

45

PDL Ratings

125

Pendant vinyl groups

196

2H-Pentafluoropropylene

100

Perfluorinated polymer backbone

Peroxide-initiated curing

25

Perfluoro(methyl vinyl ether) (PMVE)

14

Perfluorocarbon diiodides

58

Perfluoroelastomers

6 51

FFKM Perfluorophenyl cure sites

18

Peroxide curing

Phosphatizing

25

31

14 77

40 236

14

86

93 227

95 254

195

85

vulcanizate properties of

86

Peroxide level Peroxide systems Peroxide-curable fluoroelastomers Peroxide-curable gums Peroxide-curable perfluoroelastomers

110 8

32

294

299

Peroxide-curable products

294

Peroxide-curable VDF/HFP/TFE fluoroelastomers

294

197

292 292 83

Phosphonium salts

83

Piston injection unit

113

Plant tests

307

Plasma processes

197

Plasticization

289 304

Polar fluids

196

resistance

20

Polyamine curative

119

Polycaprolactone

305

high density

304

linear low density

304

Polymer

86

94

196

Polyethylene

6

study

83

93

Phosphonium accelerators

high-fluorine

281

86

77

Plastics

280

fluoroelastomers

applications engine oil additives

Permeation test method Thwing Albert cup

6

Phenolates

237 28

Permeation rate

311

19

Perfluoroisobutylene

90

Pharmaceutical 195

8

Perfluoro(alkyl vinyl ethers)

applications

systems

Links

87

composition

54

degradation

95

desired composition

57

dispersion

37

estimates of composition

53

formed in the reactor

37

isolation

38

optimizing viscosity

58

pellets

106

radical propagation of particles

46

radicals

86

scale-up

56

Peroxide-curable VDF/PMVE/TFE elastomers

90

VDF/HFP/TFE

259

Peroxide-cured terpolymer

96

VDF/PMVE/TFE

243

259

359

Index terms

Links

Index terms

Polymer (Continued)

Links

Properties

viscosity control

53

Polymeric peroxide

27

Polymerization

42

by varying composition

13

Propylene copolymerization

55

15

commercial production

39

copolymers

9

conditions

49

flammability

34

emulsion

37

properties

32

heat of

50

inhibitors

29

products

28

living radical

58

tetrafluoroethylene

30

process safety

307

rate in a CSTR

52

Q

removal of heat

51

Quaternary ammonium salts

shutdown

55

Quaternary phosphonium accelerator

250

Quick-connect seals

287

Polymerization rate

44 54

second stage

61

semibatch reactors

56

Polymerization systems

39

Polytetrafluoroethylene thermoplastics

93

52

47 56

56

53 59

83

R 42

Radial squeeze

289

Radical adducts

86

Radical growth aqueous oligomeric

Post cure temperatures adhesion systems

Pyrolysis

Radical trap 292

47 83 237

195

196

48

52

57

Post curing

118

Radical-generation rate

Pot

112

Radicals

Power generation facilities

299

determining number of

44

Power systems

117

entry efficiency

53

Power train systems

241

estimating cumulative

58

flux

43

lost by recombination

43

nonionic

43

propagation

46

Precompounds ®

Dai-el

253

VDF/HFP

245

VDF/HFP/TFE

253

249

250

Premature crosslinking (scorch)

78

rate of conversion

39

Premature curing

87

ratio of

39

summation of generated

58

Press heating system

112

Primer curing

292

Ram injection units Random copolymerization

Production worldwide

41

Propagation reactions

39

41

Rate

3

Propagation rate coefficient

113

44

of aqueous-phase oligomerization

50

of constant initiation

58

57

360

Index terms

Links

Index terms

Rate (Continued)

Links

mill

104

Runners

116

conversion

39

of decomposition

42

determining

48

S

goals for monomer feed

53

Safe handling

of incorporation of monomers

39

of polymerization

44

52

of monomers 56

See also Polymerization

307

Safety fluoroelastomer life cycle

307

of radical-generation

57

handling of monomers

33

of transfer

49

tetrafluoroethylene

27

Ratio of radical types

39

Salt removal

Reaction temperature vinylidene chloride

26

Reactions

38

Scorch

112

Screen pack

108

Seals

chain transfer-to-polymer

59

for aggressive fluids

197

kinetics relationships

39

application

260

Reactive fluids

126

automotive

295

Reactivity ratios

40

automotive transmission

296

FTPE

304

estimating

40

Reactor

41

groove geometry

19

dynamics

53

for high-temperature

jacket cooling of temperature

51

o-rings

jacketed cylindrical

55

oil retention

volume

56

performance at low temperature

17

shaft

10

Reciprocating screw injection unit

114

Secondary nucleation

Recovery from strain Redox initiation persulfate-sulfite

5 95 18

Redox initiator

42

Redox rate

43

Relative viscosity

Reversion

Semibatch reactors

47 42

43

47

50

53

55

57 54

design and operation

55

48

design considerations

56

48

limitations

54

operation

37

scale-up

56

5 288

Semiconductor applications

Rubber cure characteristics

110

injection mold

113

10

291

57

Relaxation from strain

control of

3

charging

Relationships dependence

Semibatch emulsion polymerization

196

196

Service temperatures in chemical processes

197

197

361

Index terms

Links

Index terms

Set resistance o-ring Shaft seals

engine oil additives 196 3

10 295

295

Shaw Intermix

105

291

engine oil additives Supernatant fluoroelastomer Surfactants

245

load cell

245

load stand

288

Silane primers

292

fluorinated anionic Suspension polymerization advantages bisphenol-curable

oil seals

293

Sustained particle nucleation

seals

291

Swell

Soap

107 37

119 11 46 44 39 59

varies with fluorine

60 50 14

44

concentration

46

Sodium alginate

119

TAIC radical trap

86

Solubility equilibria

280

Tangential rotors

105

T

Solubility limit

53

Tecnoflon FOR 4391

282

Solution coating

303

Tecnoflon FOR 50HS

245

Tecnoflon FOR 90HS

245

Solvent ozone-depleting Sour fuel effect of

61

Tecnoflon N 535

283

288

Tecnoflon TN Latex

303

288

Temperature

Sprue

112

Static seals

243

cycling

260

jacket-coolant

performance Steady state permeability

280

Sterilization steam

197

Stock

116

control systems

severe

293

106

Tensile strength

108

Stress

Succinimides

296

Temperature stability

temperature

Strip feeding

57 291

vulcanizate

relax

243

seals

104

recovery from

52

Temperature environment

to rolls Straight head extruder

60

Suspension products

Silicone

Single-screw extruder

292

Suppliers

Shawbury-Wallace jigs

292

Sulfides

294 automotive

Links

5 118 118

196

and heat resistance

195

Termination reactions

43

Terpenes polymerization inhibitors Terpolymers bisphenol-curable

29 96 254

287

362

Index terms

Links

Index terms

Terpolymers (Continued) composition ethylene/TFE/PMVE TFE and PMVE TFE/P/VDF VDF/HFP/TFE

chemical resistance 15

TFE/P/VDF

227 41

Test block

96 234

chemical resistance

296

14

87

119

TFE/P/VDF terpolymers

295

243

253

282

TFE/PMVE

39 289

Tetrabutylammonium hydrogen sulfate

83

Tetrafluoroethers

27

Tetrafluoroethylene

26

copolymers

296

9

cracking

29

epoxide

27

explosive hazards

27

in fluoroelastomers

25

properties

27

synthesis

27

Tetraphenyltin

93

17

TFE/propylene

227

Thermal black

245

Thermal expansion

196

Thermal resistance

8

engine seals

295

TFE/PMVE

94

Thermal stability

254

Thermoplastics

281

THV fluorothermoplastics

304

Thwing Albert cup

281

Tie-coats

292

Toggle clamp

114

fluoromonomers TR-10 test Transfer agents

particle formation

45

semibatch reactor

49

TFE/olefin elastomers

77

Transfer coefficient

49

Transfer mold

293

three-plate multiple cavity

293

113

Transfer molding process

112

96

Transfer pad

112

FEPMs

236

Transfer rate

49

fluid resistance

236

Transfer reactions

48

peroxide-cured

234

Transition zone

TFE/P dipolymer

295

Triallyl cyanurate

85

TFE/P fluoroelastomers

294

Triallyl isocyanurate (TAIC)

85

chemical resistance

294

dipolymer vulcanizates

6

TFE/P/TFP bisphenol-cured

234

vulcanizates

234

TFE/P/TFP elastomers

9

14

33

TFE/P

93

33

explosion potential

chemical resistance

233

Toxicity

TFE

TFE/olefin FEPM elastomers

227

TFE/P/VDF elastomers

234

Terpolymers and tetrapolymers compositions of

Links

9

19

radical trap

108 237

254

93

94

196

Triazine crosslinks

18 195

Triethylenetetraamine

119

Trifluoropropylene

100

227

363

Index terms

Links

Trifluorovinyethers

27

Trimethallyl isocyanurate

85

Triphenylphosphine oxide

82

237

Index terms 254

Links

iodine-containing

254

latex

303

peroxide-curable

254

Tubing die

108

peroxide-curable fluoroelastomers

Two-part liquid systems

304

precompounds

Two-roll mills

103

terpolymers

60 253 15

243

253

287 vulcanizates

V Variable speed DC drive VDF copolymers

108 6 51

44

49

90

VDF/HFP/TFE elastomers

291

VDF/HFP/TFE terpolymers

293

seals VDF/PMVE/TFE

291 31

commercial

48

continuous emulsion polymerization

50

peroxide-curable

particle formation

45

products

50

with soap

48

ternary diagram

17

systems

44

terpolymers

89

VDF homopolymer

59

vulcanizates

90

VDF production

26

VDF-based fluoroelastomers

18

VDF-containing fluoroelastomers effects of fluids VDF/HFP

VDF/PMVE/TFE elastomers chemical resistance VDF/PMVE/TFE fluoroelastomer

296

VDF/TFE copolymers

125 13

118

260

293 293 293 41

Veneer barrier layer

282

Vent stacks

299

Vented barrel design

108

Ventilation

307

Vertical ram machine

113

bisphenol-cured

111

copolymerization

40

copolymers

78

82

dipolymers

77

304

elastomers

96

Vinyl ethers

33

fluoroelastomers

77

Vinyl groups

196

287

precompounds

104 250

245

VDF/HFP/(TFE)

60

77

polymerization

49

products

50

Viscosity

90

inherent

48

VDF/HFP/PMVE/TFE VDF/HFP/TFE

bimodal polymers

249

Vinyl monomers

33

Vinylidene fluoride

13

physical properties

25

production volume

25

77

78

82

intrinsic

48

119 259

243 299

253

polymer

52

relative

48

stocks

246

60

bisphenol-cured

299

gum

253

high-fluorine

299

®

Viton polymers high-fluorine

292

254

243

259

364

Index terms Viton® B-202 Viton® Curative No.

Links 283 50

®

104

®

234

®

Viton F605C

282

Viton® Fluoroelastomer

126

Viton E-60C Viton Extreme™ TBR-605CS

®

304

®

260

®

Viton type nomenclature

16

Volatile materials

86

Viton FreeFlow™ additives Viton GLT

Index terms

250

Volatile products measurement of

307

Volume swell elastomers

282

Vulcanizates chemical resistance

195

ETP

100

fluid resistance

195

heat resistance

195

peroxide-cured

227

properties

86

250

260 temperature stability

196

with varying fluorine

14

VDF/HFP/(TFE)

96

Z Z-mer

45

47

254

Links