Environmental Impact of Textiles

Environmental impact of textiles

Environmental impact of textiles Production, processes and protection Keith Slater

CRC Press Boca Raton Boston New York Washington, DC

Cambridge England

Published by Woodhead Publishing Limited in association with The Textile Institute Woodhead Publishing Ltd Abington Hall, Abington Cambridge CB1 6AH, England www.woodhead-publishing.com Published in North America by CRC Press LLC 2000 Corporate Blvd, NW Boca Raton FL 33431, USA First published 2003, Woodhead Publishing Ltd and CRC Press LLC © 2003, Woodhead Publishing Ltd The author has asserted his moral rights. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. Reasonable efforts have been made to publish reliable data and information, but the author and the publishers cannot assume responsibility for the validity of all materials. Neither the author nor the publishers, nor anyone else associated with this publication, shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming and recording, or by any information storage or retrieval system, without permission in writing from the publishers. The consent of Woodhead Publishing and CRC Press does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from Woodhead Publishing or CRC Press for such copying. Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. Library of Congress Cataloging in Publication Data A catalog record for this book is available from the Library of Congress. Woodhead Publishing ISBN 1 85573 541 5 CRC Press ISBN 0-8493-1778-9 CRC Press order number: WP1778 Typeset by Ann Buchan (Typesetters), Shepperton, Middlesex Printed by TJ International, Padstow, Cornwall, England

Contents

Preface

ix

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10

Structure and stability of the ecosystem The ecosystem Life Necessities of life Other species Land hazards Dust Atomic radiation The Earth’s environment Environmental balance The textile industry References

1 1 1 2 4 6 6 7 7 7 8 8

2 2.1 2.2 2.3 2.4

The health of our planet Planetary stability Natural factors Human interference Changes occurring

9 9 9 10 14

3 3.1 3.2 3.3 3.4

The nature of textiles Properties Textiles as engineering materials Principles of textile manufacture Energy

17 17 17 18 18

4 4.1 4.2 4.3 4.4

Textile fibre production Scope of the industry Natural fibre production Artificial fibre production Alternative fibre sources

23 23 23 31 34 v

vi

Contents

4.5 4.6 4.7

Inorganic fibres Microbiologically stable fibres Effects on the planet References

34 37 37 37

5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 5.13 5.14 5.15

Yarn production Starting material state Washing Scouring Bleaching Carbonising Drying needs Baling Transportation Opening Carding Blending Combing and gilling Drawing Spinning Noise and dust References

40 40 42 42 44 46 48 48 49 52 53 53 53 54 54 55 59

6 6.1 6.2

Fabric production Traditional fabric production methods Other methods References

61 61 63 68

7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9

Fabric treatment processes Starting material Finishing categories Mechanical finishing Chemical treatments Other finishes Colouration Pollution aspects Printing Drying and shipping References

69 69 69 70 71 74 81 82 85 87 88

8 8.1 8.2

Use of textiles Primary and secondary production Types of use

90 90 90

Contents

vii

8.3 8.4 8.5 8.6

Normal uses Environmental aspects Household textiles Industrial and medical uses References

91 92 93 94 97

9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10

Environmental protection Commitment Protective applications Legislation Future prospects Financial benefits Costs Drawbacks Recycling Pollution measurement problems Environmental auditing References

98 98 99 100 101 101 102 102 107 109 109 112

10 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12 10.13

Effects on textiles of natural exposure Influences Degradation Atmospheric influences Radiation Changes occurring Infrared radiation Other types of radiation Mechanical action Mechanical stress in manufacture Mechanical stress in use Prediction of effects Degradative combinations Magnitude of textile environmental damage contributions References

115 115 115 117 119 121 122 122 123 126 127 128 130 134 138

11 11.1 11.2 11.3 11.4 11.5 11.6 11.7

Thermal exposure Intensity Static drying Stenters New equipment Problems Novel approaches Flammability References

139 139 140 141 144 144 145 146 151

viii

Contents

12 12.1 12.2 12.3 12.4

Chemical and microbiological attack Reagents Fibre type Planned attack Microbiological attack References

152 152 153 154 155 160

13 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9

Protection of, or by, textiles from environmental damage Aspects Maintenance Degradation during use Chemical treatments Protection of humans Modern developments Non-clothing protective needs Protection for the environment Desirable properties References

161 161 162 162 163 163 166 169 171 174 175

14

Conclusions

178

Appendix Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 Section 7 Section 8 Section 9 Section 10

Cotton scouring with enzymes Wool scouring with enzymes Bleaching with peroxide Sizing and desizing Pollution reduction in dyeing Medical applications of textiles Textile filters Sporting goods and other uses Effluent treatment Recycling References

Index

183 183 187 189 190 191 194 196 196 197 201 203 207

Preface

A piece of clothing, or any other textile article, is a very difficult and expensive product to manufacture. But not only does it cost a lot of money – our usual way of estimating how much inherent value should be placed on an item – it is expensive in another, more important, way, one which might conceivably make even money ultimately redundant. It harms the environment, the protective envelope under which we all live. If the environment is destroyed, then so are we. Let me hasten to add that the manufacture of textile goods does not provide the only, or even the most severe, stress to which our planet is subjected. There are many other products that can damage the Earth’s well-being, but the textile industry is often blamed (perhaps unfairly) far more than it deserves. The reasons are, I believe, two-fold. First, textiles are a widespread, virtually universal product, familiar to practically the entire population of the world. Second, the kind of undesirable effect that textile manufacture has on the planet is often very tangible. We see dyestuffs colouring rivers or black clouds of smoke rising from the chimney over a finishing plant. We hear the cacophony emerging from a weaving shed, twisting room or spinning mill as machines shriek noisily at us. We see the remnants of discarded clothing littering a street or rubbish dump. We see diesel trucks belching fumes as they are driven into or out of a textile plant to deliver raw materials or shipped goods. So we need to investigate the actual relationship between textiles and the environment. It is important to note from the beginning that this investigation has a double-edged meaning. The manufacture and use of textile goods can have an adverse effect on the environment, but the environment can also have, in an ironic twist, an adverse effect on textile goods. The former of these effects we normally lump together under the term ‘pollution’ and the latter we describe as ‘degradation’ of the materials. Before we can start our investigation, though, we need to be clear about what we mean by the environment. All the evidence that I have observed on the subject leads me to believe that there is not really any widespread understanding of what is actually meant by this nebulous term. We hear references to the social environment, or to the physical one, or to other such differentiations of the word into a range of individual aspects. At the outset, then, I intend to define what aspects of the environment I shall be including in this book. ix

x

Preface

In simple terms, what I hope to do is to examine what effects all phases of textile production and use have on the Earth around us, from growing or making fibres to discarding a product after its useful life has ended. I shall look at the physical environment, including the air, the water and the land. I shall also look briefly at the biological environment by considering what happens, as a result of manufacture, to other species on the planet, as well as to human beings. The effects I will be considering are not only those on our bodies, but also on our minds. The social environment as it impinges on our psychological, physical and physiological comfort will be part of the discussion, as also will our financial well-being. In short, I regard the environment as encompassing all aspects of every part of our lives. To the best of my knowledge, this comprehensive approach has not been undertaken before and has never previously been associated with textile production and use. In a sense, then, this book is a pioneering one, yet it is not strictly a new one. All it does is pull together a wide range of examples drawn from a diverse collection of sources and integrate them to form a new and coherent set of ideas. If it informs, educates or amuses you in the process, I shall be delighted. My approach might seem odd for a book that is supposed to be about textiles. I intend to deal first with the environment itself in some detail, to ensure that my starting position is understood. In this way I hope to persuade you to accept the truth, as I believe it, of the situation we, as a species, find ourselves in today and what the textile industry has contributed to this position. I intend to be entirely honest so that, if I feel that the industry is to blame for some harmful aspect or condition, I shall lay the blame squarely. Conversely, if I feel that the textile community is the victim of accusations that are giving it an undeserved reputation, or if some of its practices are not receiving the praise that is due to it, I will be equally conscientious in pointing out these facts. For this reason, I shall begin the book with chapters dealing with our fragile environment and our dependence, together with that of all the other species occupying the Earth, on its well-being. I shall examine the conditions needed to ensure a healthy, stable planet and look at what any deviation from these conditions can do to a range of species. I shall then take a closer look at how the human race, in general, has brought about undesirable changes in the planet’s health. Aspects of resource depletion, pollution and energy use will be covered. In all of these areas, to keep the focus on textiles, I shall try to find suitable examples of where the industry fits into the overall picture. Then, in the rest of the book, I shall focus more directly on textile matters. I hope first to provide a complete survey of how developments in the industry and consumers of its products have affected the planet’s health in the past. Then I will look at modern solutions that have often been proposed by ‘experts’ in areas other than textiles but adopted by the industry in the hope that some alleviation of problems can be achieved without sacrificing high textile production targets. After showing that this aim is unrealistic, I shall discuss the real ways in which the

Preface

xi

industry is responding to the challenge of keeping our planet healthy and conclude with my view of the future. In this, I hope to persuade readers that the planet can indeed be saved without abandoning all our cherished lifestyle, but that we need to be vigilant in every step we take, as individuals as well as representatives of a great and essential industry, to ensure that unfair blame is not allocated to us by outside observers. Each chapter will be divided into sections allowing subjects to be kept separate and cross-references to a specific topic to remain simple. I hope to engage both the general reader who is interested in the subject as a whole and the specialist reader who would like to follow in more detail the particular points on which I focus. With this in mind, in some chapters, I will only deal with the highlights of a topic, but will make reference to further relevant work in the Appendix, where the more technical aspects are summarised. There, I will provide references, to enable readers interested in each specific point to obtain more detailed information. Categories of pollution production, as listed in Table 1.1, will be identified by an asterisk, in parentheses and bold, italic type. My ultimate aim is to address and correct some of the fallacies shared by many people, both within and outside the industry, about the real effects of textile manufacture and use on the environment. If I am successful, we should see a more caring, clean and respected industry (which will also, almost certainly, be a more profitable one) emerging in the future.

1 Structure and stability of the ecosystem

1.1

The ecosystem

What does the term ecosystem actually mean? One dictionary gives the meaning as ‘a system formed by the interaction of a community of organisms with their environment’1 with an encyclopaedia giving the proviso2 that the assembly of organisms can be of any size and level, provided they are all free to interact together in a single complex whole and are in close relationship with the environment. In a sense then, all life, everywhere on the Earth, can be seen as a single ecosystem, or our planet’s entity can be divided into a range of ecosystems. Typical examples of such subdivision could include, say, an ocean, or the atmosphere, or a tropical forest or an urban city, and all of them would then be combined together with a host of other ecosystems to form the biosphere as a whole. What these all share in common is that they are a location where life is supported and where all forms of that life are living together in equilibrium.

1.2

Life

Next, how is ‘life’ defined? Most people could recognise a dead body when it appears on the television screen, so this familiar scenario can be used to focus attention on the differences between an ‘alive’ and a ‘dead’ state. The investigating officer can be recognised as representative of the living and the corpse is definitely a dead object. Underneath the corpse, however, is a myriad of creatures, existing in a wide range of shapes and minute sizes, some too small to be seen by the naked eye. There may, for instance, be worms, insects or vegetable matter. All of these would be unhesitatingly accepted as examples of life, but there will also be bacteria and perhaps lichens or fungi. Now, the borderline between living and non-living creatures is less certain. Further down the scale are the amoebae, washed out of the victim’s bloodstream; where do these belong in our interpretation of life? And what about the fragment of yeast, left by a final glass of wine residing in the victim’s stomach; where does that fit into the grand scheme of things? 1

2

Environmental impact of textiles

Most people would agree that the sheep that provided the wool used to make winter garments worn by the two human examples, and the cotton plant that provided the raw material for their underwear or shirts, were alive. But what about the wool or the cotton fibres after they had been harvested? And, if we accept the validity of the well-known Gaia Hypothesis3, is the Earth itself really a living creature, holding its breath to deceive us into thinking it is not alive and lurking in wait to send us all to destruction as soon as we become too much of a nuisance? In scientific terms, many of these (with the possible exception of the fibres and the entity of the Earth) are examples of living organisms. For the purposes of this book, whether or not we agree to accept the Gaia Hypothesis, the whole planet, together with its atmospheric envelope and everything inside that envelope, will be considered as a ‘living’ ecosystem. After all, if any portion of this entity is destroyed or ‘killed’ by any action of ours, then the entire system is likely to go into a tail spin and end up as a lifeless hulk, along with any residual bits and pieces of all its inhabitants, including us.

1.3

Necessities of life

For a healthy existence, there are certain necessities that must be widely available. Not all the ‘living’ parts of the ecosystem require all of them and some ‘living’ units may be able to survive without any of them, but the vast majority of this planet’s inhabitants need four commodities for their survival. These are, in order of frequency of need for humans and other higher animals, clean air, clean water, food and protection from external or internal ambient conditions.

1.3.1 Air If human beings are considered to be the typical example of the most developed of the inhabitants of the planet, we can examine each of the necessities of life in turn as they relate to humans. The oxygen contained in air is needed to allow the cells of the human body to effect its continuing existence. Blood carries oxygen to remote parts of the human body where it oxidises impurities and transports the products of this reaction as waste to the lungs (or other appropriate places) for removal. In order to survive, oxygen is needed on a more or less continuous basis; in its absence, survival will only be maintained for about four minutes without experiencing irreversible brain damage and clinical death will follow in about six minutes. Unfortunately, the air has to be pure. Nitrogen can be tolerated as a diluent for oxygen, and to some extent carbon dioxide, but in modern times there may be other constituents of air that are much less acceptable to the human system. If there are toxic materials or an excessive quantity of carbon dioxide present, then human beings are likely to succumb to the hazards of these impurities and to suffer illness, or even death. Other lower organisms in the biological kingdom share this

Structure and stability of the ecosystem

3

regrettable inability to survive in a poisonous atmosphere, but there are some recipients who might thrive on such compounds. The most obvious example is plant life, which absorbs carbon dioxide and converts it into oxygen, replenishing the supply of this vital (to animals) gas. This happy coincidence will be discussed further, later in the book. There are also certain bacteria that can be trained to gobble up oil slicks or other forms of pollution when an emergency spill takes place.

1.3.2 Water The second need is for water, a substance that constitutes over 90% of the human body. Again, the water must be pure; the slightest trace of bacterial contamination can bring on a marathon attack of various illnesses that manifest themselves as vomiting and diarrhoea. The cause of this reaction is a protective mechanism that reacts to get rid of the offending impurity as quickly as possible, especially if the immune system involved has not developed natural arrangements to give it the ability to deal with the contamination. The need for the actual water, though, is much more critical. Human beings could survive the bacterial invasion, and do so on a regular basis, but cannot survive the absence of the water that carries these bacteria. The human body consists of millions of cells, each of which includes water. The 90% figure mentioned above results from water being taken up by these cells and combined to make some form of chemical compound that is an essential component of the specific cell or of its ability to function. Cells are living organisms, so change constantly. Impurities arising as a result of their operation are removed, usually in aqueous solution, so the water that washes away the waste products has to be replenished to allow the cell to continue living. A fresh supply of water has to be available for the cell to recharge itself and this is where the need for water arises. Without water, the cell would dry up and die, then be rejected as waste in its own turn by the body. Obviously, if there is no water, there can be no healthy cell replacement, and if every cell is rejected as waste, there will not be much left of the body to keep life ticking over. One small consolation is that the person would not know much about such a disaster, because brain cells, which require replenishment very frequently, are lost early on in the dehydration process and madness quickly sets in if water is denied. Lack of water can drive human beings insane in a matter of a few days. Death does not take much longer.

1.3.3 Food A human body needs vital chemical substances to sustain its existence. Nutrition is the process by which the body takes up these chemicals and converts them to muscle, fat, blood, energy and all the other important bits and pieces that are needed to continue functioning in a healthy manner. Without food, we become

4

Environmental impact of textiles

angry, impatient, listless and eventually unable to sit up and retain an awareness of life around us. Most human beings can survive for weeks without food (as long as water is available) before succumbing to starvation. People can also survive for years without adequate nutrition, as evidenced by the grim pictures shown on our television screens from time to time when famine strikes in some of the less fortunate regions of the planet.

1.3.4 Protection The last crucial need is one that humans have continually and considerably refined over the last few millennia. As primitive creatures, our forebears were able to survive in the wild, just as animals do today, with little or no help from artificial (i.e. non-natural) sources. In modern times, that ability has been lost, mainly as a result of our determination to cosset ourselves with all kinds of luxury. The consequence is that now humans cannot survive without some form of protection. This is of two broad types: shelter as a shield from other forms of life and from the elements and textiles as protection from these same elements and from the harmful effects of abrasive or wounding contact with objects that are encountered throughout life. The textiles also provide mental protection in hiding our bodies from the gaze of other people, a subject that will be discussed again later. In both types of protection, the primary purposes are to keep the body’s integrity intact and to allow its built-in mechanisms to remain functioning without unduly overloading them. We continue to exist and move about because our hearts pump blood around the body, our gastrointestinal systems convert food energy to a useful form, our thermoregulatory systems keep our bodies within a satisfactory temperature range, our cardiovascular systems continue to supply fresh oxygen and remove excess carbon dioxide and our muscles continue to operate without getting wasted away or suffering from spasms. Without any of these advantages, we would run a grave risk of dying. One of the purposes of textiles is to support the body in retaining them.

1.4

Other species

What can be said of animals and plants? The larger animals that provide us with textile fibres, such as sheep, goats, camels, and so on, have similar needs to our own. They need air, water and food to survive. They are, though, not as dependent as we are on pure water, because they are able to tolerate pollution of various kinds without harm. They generally also do not need external protection, since they already have warm coats (which are, of course, the bits that humans take for textile raw materials) to fill this role. Smaller creatures that produce textile fibres, such as silkworms or spiders, are even less demanding in their vital requirements, though the silkworm produces poorer quality fibres in the absence of an optimum diet. The plants that are used to make our textiles will thrive to some extent even if

Structure and stability of the ecosystem

5

Table 1.1 Categories of pollution production Code

Type

Emission

Effects

A-1 A-2 A-3 W-1

Air Air Air Water

Carbon dioxide Toxic gases Smoke Heat

Greenhouse gases Poisoning of species Visibility loss Fish stress

W-2 W-3

Water Water

Colour Toxic liquids

L-1 L-2

Land Land

Salts Toxic solids

L-3

Land

N-1

Noise

N-2 N-3 V-1 V-2 V-3

Noise Noise Visual Visual Visual

Microbiological hazards Moderate HF and LF Loud HF Loud LF View obstruction Discarded garbage Smog

Typical example

Burning wood Burning rubber Tenter exhaust Power station effluent Potability concerns Dyehouse effluent Poisoning aqueous Chemical plant species effluent Plant growth stunted Ice salt Food chain poisoning Agricultural chemical discharge Disease or death Manure discharge

Psychological nuisance Deafness Building damage Aesthetic loss Landfill overload Limited visibility

Rock music Spinning frame Weaving shed Hoardings Textile waste Coal fires

HF and LF represent high and low frequency, respectively.

adequate conditions are not provided. Thus, cotton, linen or bast fibres will continue to grow even in poor soil, though the fibre quality is, once more, lower in the absence of good nutrition. Like all plants, they will benefit from excess carbon dioxide, even in amounts that would be fatal to human beings. In many cases, too, pollution of certain kinds may actually be advantageous. Manure, for example, is highly beneficial for a plant to thrive, in direct contradiction to its toxic behaviour as a source of the potentially dangerous (to human beings) E. coli organism. Where they lack endurance is in the matter of temperature and light tolerance; plants will die in cold or dark ambient conditions that would be accepted with little trouble by human beings or other animals. There are some chemical compounds that are harmful to plants as well as to animals. These substances will be brought into sharp focus in the later parts of this book. They can be loosely classified into various categories, as shown in Table 1.1, where they are grouped according to the harmful effects they produce in different living species. There are, naturally, many more substances than are shown in Table 1.1. The list is intended only to illustrate the type of harmful behaviour that can be produced. Later in the book, one or more of these types will be referred to wherever a compound that is environmentally undesirable in some way is derived from a textile-related activity. The occurrence of pollution will be identified by an asterisk

6

Environmental impact of textiles

with the specific category code placed in parentheses, bold-faced and italic (see Table 1.1). Thus, a toxic gas poisonous to any species, whether animal or plant, will be referred to as (* A-2) in the text. The need of flora and fauna for a non-toxic environment is the root cause of the importance of cleanliness in air and water. Even if the contamination is a very small proportion of the air or water, it can still be harmful. To recognise the truth of this statement, imagine breathing a sample of air, or swallowing a glass of water, containing an almost insignificant quantity of cyanide. Thus, both the nature and the amount present of a pollutant should be taken into account in determining the potential harm of each substance. This approach is used by governments in arriving at legislation defining the permissible level of contamination of harmful substances, as will be discussed in a later chapter. Amounts exceeding these levels may not be fatal, but are likely to cause sickness in a species susceptible to their harmful effects. Other consequences that should be considered may include genetic changes, fertility loss, lower survival rates or lifetimes and the onset of diseases that would not exist in the absence of the contaminant.

1.5

Land hazards

It is not only in the air or water ingested that caution has to be observed. The land itself can also be a source of harm to those living on or feeding from it. Toxic agents in water may be washed into the soil and find their way into growing plants. Harmful substances in the air may be deposited onto the ground, or may be absorbed by components of the soil, again being transferred into plants. The harmful chemicals will eventually be washed out of the soil and into drinking water supplies, so it is virtually impossible to take adequate precautions against the unpleasant consequences of land pollution. The effects of this movement are that the toxins enter the food chain, either via plant absorption or after animals have drunk them. Eventually, as a result of the predator–prey relationship, they end up in the bodies of many other species, including our own, where their adverse effects will ultimately make themselves known in the all-too-familiar forms of food poisoning. Aquatic species, whether fish or plant, are particularly rapidly susceptible to this type of harm, since they are totally dependent on water (which may be heavily contaminated by the chemicals washed off from the land at an early stage of the distribution process) for their successful functioning.

1.6

Dust

We should not ignore various miscellaneous types of activity that can prove harmful to the planet or to its inhabitants. The first of these is the dust that is present everywhere, in large or small amounts. Dust is formed by microscopic-sized particles produced when some larger object breaks down. The larger object may be a soil crumb, or the skin on an animal’s body or portions of a plant. In the context

Structure and stability of the ecosystem

7

of this book, it may be the textile fibres being processed in a mill or the solid residue after a substance (such as a starch or finish) has been applied to a fabric. Dust, of whatever kind, is responsible for a number of ecological problems. If its origin is soil, then the disappearance of that soil means that plants dependent on it will not grow as well. If it is from an animal or plant, then the effects of its presence may include setting up allergic reactions in other creatures (including humans) nearby. If it is from a textile fibre, or other substance in the mill, then workers in the vicinity may suffer from serious illnesses, in the form of severe lung diseases from breathing it in too high a concentration. Dust can also cause deterioration of nearby objects, either by abrasion (as on buildings, for example) or, in the textile case, by producing a dirty product or by bringing about wear in a fabric structure or machine component.

1.7

Atomic radiation

Atomic radiation should be included in this survey of environmental contaminants. If a radioactive substance comes into contact with a living cell, the radiation emitted can bring about harmful changes in the structure of a cell. These may confer on cells an inability to divide in a healthy manner, or (for larger organisms) prevent the organism from reproducing correctly. The result may be unhealthy offspring, a failure to operate correctly or, in the limit, an inability to survive. Even low-level radiation, such as that present in equipment designed to measure thickness, evenness or static electricity in textiles, is now suspected of being dangerous on long exposure, so precautions have to be taken to shield human beings from its presence. Power stations are an obvious modern source of atomic energy. The accidents that have happened internationally over the past few decades are a constant reminder of the dreadful destructive power of atomic radiation.

1.8

The Earth’s environment

It would not be ethical to omit the Earth’s own environment from our list of origins of problems. Virtually all the harmful sources that have been specified as being risky in this chapter occur in nature. The Earth is constantly being bombarded by cosmic radiation from the universe. Dust storms arise in dry seasons. Volcanoes spew out toxic fumes. Forest fires, started by lightning strikes, increase the concentration of toxic chemicals and of carbon monoxide or carbon dioxide in the air. Water is contaminated by animal excrement. Natural sources of radium or uranium bring about genetic modification in animals living near them. Solar radiation can cause skin cancer in animals or loss of water from natural habitats that provide shelter, food and drink.

1.9

Environmental balance

Environmental balance is delicate and sensitive. Without human interference, the

8

Environmental impact of textiles

Earth has, over the millions or billions of years of its existence, managed to bring about a stable equilibrium, so that all natural creatures can survive in harmony with the planet. Unfortunately, the presence of humanity, especially since the days of the Industrial Revolution, when mechanical aids were found that enhanced the meagre powers of human beings, has changed matters in drastic ways. Nature can now be overridden and harnessed at will. We can take all we want from the planet and pay no heed to the effects that our behaviour might have. Or so we used to believe. Now, though, there are signs that the planet’s ecosystem is responding in a way that bodes ill for the future and even for the survival of human beings on Earth. Environmental harm is increasing. The adverse effects that human behaviour can have on nature and, in the limit, on humanity itself are beginning to be noticed. Indeed, some scientists believe that we are on the brink of causing such adverse reactions and that we are already on, or possibly past, the threshold of destroying our prospects for survival. We appear to be happily acquiescing to our own self-destruction; we rush to buy the latest car or computer or furniture or household appliance or other such gimmick long before we need to do so for utilitarian purposes. Our motivation is often purely to display status or wealth, not taking account of the enormous environmental costs incurred.

1.10

The textile industry

In this headlong rush towards self-extinction, the textile industry, because of its major and ubiquitous presence on the Earth, must share some of the blame. The exact amount of its responsibility has never been established (and, indeed, may be impossible to establish). Thus, the first aim of this book is to identify which textile processes are harmful to the health of the Earth and to arrive at an estimate of the extent to which their contribution may be guilty. The second aim is to attempt to judge how much of the harm being done is fairly attributable to the textile industry and how many of the accusations levelled against it are unfair. In the following chapters, the textile production process will be examined, stage by stage, comparing the textile industry briefly with other industries with respect to environmental harm. It will then be shown how the environment itself can turn the tables by being harmful to textile goods. By the end of the book the reader should have been provided with a factual and realistic assessment of what problems are associated with textiles and how the industry, or consumers, can help to reduce them.

References 1 Fleamer, S.B. and Harch, L.C. (eds), Dictionary of the English Language, 2nd edn, New York, Random House, 1987. 2 Parker, S.B. (ed), Concise Encyclopaedia of Science and Technology, 2nd edn, New York, McGraw-Hill, 1978. 3 Lovelock, J.E., Gaia: A New Look at Life on Earth, Oxford, 1979.

2 The health of our planet

2.1

Planetary stability

Now that what factors constitute a stable ecosystem have been examined, the factors that maintain stability and, if stability is not maintained, what factors bring about perturbations in the environmental equilibrium that disrupt the desired state can be addressed. The first point to make is that any equilibrium is temporary in nature. We live on a planet that is doomed. Even if we were not and had never evolved, the Earth would not survive for ever. It may take a long time to disappear all on its own, but its disappearance as we know it will take place in due course. The sun, like all stars, will either expand or shrink before reaching its final state of oblivion. Depending on which of these two takes place, the Earth will either be swallowed up (with everything on it charred) or be lost to outer space because gravitational attraction can no longer keep it in thrall as a planet. In that case, it will become just another dead piece of rock floating in space. The Earth, moreover, is limited in its ability to support life and no miracles are available to change this, either in the short or the long term. The demise of the dinosaurs provides proof that no species can expect to survive for ever. The balance that allows the Earth and all its inhabitants to continue to exist is a very delicate one, established over aeons of time. It involves an equilibrium between all the elements present here, especially the air, the water and the land, which has been achieved by natural processes too complex to consider in any detail here, but which have brought about the miracles of planetary stability and life. If an imbalance occurs in the equilibrium existing on Earth, then survival of more than just people can be jeopardised. Unfortunately, imbalance can arise from natural causes, as well as from the habit of humanity of inflicting on the planet the kind of interference that is the subject of this book.

2.2

Natural factors

As can be seen from the examples introduced briefly in the previous chapter, there 9

10

Environmental impact of textiles

are many natural factors than can disturb, or even (in the course of millennia) destroy completely, the stability of the planet. Geological and fossil records show that, over the long period since its creation, the Earth has only been able to sustain recognisable life forms for a minute fraction of its existence. The basic structure of the planet has been ripped apart many times by natural sources of change that include plate tectonics, volcanic eruptions, solar radiation and, more recently, the existence of weather variations. The former two bring about massive changes, causing continents to shift and mountains to be lifted or destroyed. Solar radiation may cause droughts that can alter the appearance of the countryside, changing it from green to brown, and can initiate melting of the ice caps, with severe flooding of the land as a consequence. Extreme weather conditions, where excessive amounts of rain fall or winds blow, can also produce flooding capable of washing away trees, removing topsoil or bursting the banks of rivers to redefine the landscape. Even relatively small amounts of rain are capable of washing away topsoil, reducing plant growth, leaving the land more barren and, once more, changing the face of the Earth. The sun has other potentially harmful side effects. Cosmic, ultraviolet or infrared rays can accelerate changes in the process of mutation, causing organisms to become modified at a far greater rate than would normally be expected on theoretical grounds. Protective arrangements are in place to prevent some of these changes, consisting of such checks as the filtering effect of the atmosphere or the compensating factor of tree growth for volcanic gas emissions. Ever since they have evolved, animal and plant species have acted as prey or predator for each other, maintaining numbers of each type of creature at an approximately constant level. Chemical reactions (the neutralisation of excess acidity by the solution of limestone, for instance) keep the Earth’s soil in a state that will permit plant growth to continue. All of this means that the Earth’s environmental balance is in an extremely delicate and sensitive state.

2.3

Human interference

Sadly, one group of the planetary family does not seem to fall in with the system of checks and balances that should keep things plodding along happily; human interference has constantly upset this ideal situation. As a species, we have interfered with nature virtually since the day we began to exist. Our entire aim has been to adapt the world around us to enhance our own stature, comfort, wealth or other state that is perceived to be desirable. Of the myriad reasons why we carry out such changes, many depend on some form of textile assistance. These reasons should be carefully examined in preparation for the investigation of textile importance in environmental changes. They can be broadly categorised into three distinct types: survival or protection, war or weaponry and desire for possessions.

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2.3.1 Survival First and probably most obvious is the matter of survival. Animals are content (or so it must be assumed) to live their allotted life span without any effort to prolong it. This is in direct contrast to the human animal. If we can, we will prolong our lives to the last instant, often after natural death should have taken place, and have always had the desire to do so. Our distant forebears developed tools to defend themselves against animals of superior speed and strength. They banded together to outwit prey that would otherwise have escaped, leaving the human beings without food. Once the food was killed, they dragged it home to their kinsmen with the aid of twisted strands of grass, vines or other units that formed the earliest ropes (and probably the earliest true textiles). The only animals they could not easily defeat were those too small to be seen, like bacteria, or those of comparable size and intellect, other human beings. Against the former, they began to practise simple medicine, using the Earth’s resources to produce healing foodstuffs, drugs, balms or ointments. They also used textiles in the form of primitive cloth coverings that kept a wound clean to aid in the healing process. As time passed, they developed means of protecting themselves against dangerous sources of infection, often by adopting textile structures to prevent damaging contact with sharp rocks or other surfaces. Today, we use medical technology to protect us against disease by means of inoculations that have a history dating back to Edward Jenner in the 17th century. If this fails, we try, with an intensity that has accelerated enormously during the last 50 years or so, to conquer the disease by using cures that have slowly evolved since ancient times. If even the drugs fail, surgical intervention may be attempted, dating back at least to Ancient Egypt and evolving slowly in distinct steps since that time. Finally, if surgery is not immediately effective, a patient may be attached to machinery that takes over completely the body’s functions, so that the person can stay alive indefinitely in a state of suspended life. In a modern hospital, textile products are omnipresent, appearing as implants, tissue engineering, hygiene and health care products, protective covers for wound operation sites, bandages, uniform clothing, bedding items, operating room gowns, packaging for surgical instruments or in a host of other applications.

2.3.2 Conflict In the second broad category of how humanity has changed the environment, and in the face of competition from each other, human beings have adopted the art of fighting, aided by the evolution of weaponry. The earliest weapons, made of flint, took a long time to prepare, so fatalities must have tended to be less numerous. Human ingenuity then brought about improvements in weapons by the development of newer materials, such as copper, bronze and, ultimately, iron. Protection against some of these could be achieved by means of clothing, so the techniques of

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Environmental impact of textiles

textile production evolved alongside those of attack against animals or human beings. It has always been the author’s contention (though it is unlikely ever to be proved) that skill in making textile materials is the major, or even sole, reason of the survival of any specific group of human beings. For instance, a clan using the optimum size of spinning whorls would probably defeat one using whorls of inferior size. The reason is obvious; an optimum whorl produces a better (that is, stronger) yarn because it provides better twist, evenness and fineness. If the yarn is better than that of your rival, then so is the fabric. If the fabric is stronger, then two results inevitably follow. First, it will give better protection, allowing the wearer to enjoy an increased chance of survival in combat. Second, it will not need replacing as often, which means that the people spinning the yarn and weaving the cloth can devote the time saved to other tasks, such as food gathering or child care, that will aid the survival of the clan. In our own day, and at close quarters, we have devices that can injure or kill an opponent by a simple movement of a finger on a trigger or button. We have weapons that can destroy our enemy at a distance, even as far away as the other side of the world. These weapons can be attached to vehicles that can cross rough terrain, travel on top of the sea, fly through the air or even venture outside our Earth’s atmosphere before returning to deliver their burden of death. Once again, textile products support these activities in the shape of uniforms, parachutes, camouflage, webbing, seat cushions or other aids to enhance the effectiveness of the battle unit.

2.3.3 Possessions But survival and protection are not the only aims of human existence. Another powerful driving force is the desire to acquire and keep possessions or goods. Since about 7000 BC, when the first civilisations appeared, human beings have been concerned with ensuring that their possessions stay with them as long as they are alive. On their death, apart from the grave goods buried with them as necessities for their comfort in the afterlife, all their possessions had to be passed on to their legitimate offspring to be kept as a part of the wealth of their true descendants. Anthropologists assure us that modesty, the refusal to expose the human body to other people not permitted to view it, began as a means of preventing illicit sex between the wife of one man (her ‘owner’) and another man, so helping to ensure that any child born to the woman did indeed have her ‘owner’ as its father and could inherit his wealth. With the passage of time, this characteristic for acquiring goods, which modern humans tend to equate with status, has become so entrenched that we now clutch fiercely to all we own. Despite our protestations to the contrary, our laws, religious beliefs and social standards do not regard all people as being equal. We happily heap adulation on the chosen few who have obvious wealth, even though that wealth may be built on what many people would regard as spurious worthiness.

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This wealth has to be displayed to all and sundry, and one manifestation of this is the wearing of elaborate, conspicuous clothing made from the richest cloths and the most up-to-date fashions, just to let people know that we have, indeed, acquired ‘eminence’ in the world. At the same time, we casually ignore the plight of millions of our fellow creatures who are on the verge of extinction because they have insufficient food, or water, or money for medical supplies. The need for possessions is not confined to individuals. Countries or regions, too, can exhibit an acquisitiveness that can be harmful to our planet. Disputes flare up on a regular basis over land, often of such poor quality that it seems pointless to bother about. Access to water, or the rights to extract oil, or coal, or gold and other precious metals, or diamonds, or a whole host of similar valuable minerals, are also frequent causes of disagreement between nations. In our pursuit of the wealth represented by these displays of ostentation, we almost invariably make use of textile products. The protective clothing worn by prospectors or workers in hostile climates, the cloth used in filtration processes to extract or purify the minerals, the tarpaulins covering the area or sheltering examination sites; all of these are examples of textiles that simplify, or sometimes even make possible, the extraction of the minerals. So too are the uniforms and camouflage of the armed forces whose presence is necessary to defend the land once it is annexed in order to keep possession of it.

2.3.4 Curiosity We must not forget the other related acquisitive human trait of curiosity. From their first days, our distant ancestors had an urge to investigate and to explore. The earliest human migrations, spreading the new species over the entire surface of the globe, may have been the result either of curiosity about new terrain or a need for self-preservation in the fight for scarce food resources, but later movements were certainly motivated by inquisitiveness. From explorers looking for new markets or new routes to existing ones in ancient times and in the age of discovery that took place principally in the 15th to 19th centuries, to the modern family going abroad for a holiday, human beings have been driven to spread their presence far away from their place of origin. Once again, textiles in the form of clothing (for personal wear or for trading), sails, or tents, or seating and tyre cords in transportation, have played a vital role in ensuring the success of these excursions. Indeed, without them it is entirely possible that our species would never have survived the rigours of the inhospitable climates they must have met on their early migrations, so that it can be fairly claimed that we owe our very existence to these ubiquitous materials. Our curiosity does not end with travel around the planet. We are now exploring parts of the universe outside our planetary limits and in the not-too-distant future we will probably begin to embark on journeys beyond our own galaxy. For all of these pursuits, textiles have been called into service. Space suits, isolation garments,

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Environmental impact of textiles

filter fabrics and other such refinements can be added to the list of uses already summarised. We also explore the Earth about us in ever more increasing detail, from the plants or animals that surround us to the minute particles from which they and we are made. We extend our enquiries into the very bodies, or even minds, of our own species, trying to discover what makes us work. In the immediate future, it will almost certainly be possible to make a copy of ourselves, once we have overcome (or ignored) the ethical scruples we have that deter us from creating life by artificial means. Textile structures are often used as a framework for culturing replacement organs and body parts, so may well play a significant part in prolonging life and increasing the planet’s population burden. In all of these many characteristic traits of modern human existence, our motivations closely reflect those of our ancient ancestors, enabling the route by which we have arrived at our current attitudes to be easily traced. One issue that will be explored in the rest of this book is the effect that all this activity has had on the health of our planet, and what can still be done (especially in the context of textile production or use) to keep it in as healthy a state as possible. In general, there are two overall planetary problems brought about by the consumption created by our determination to survive, enjoy luxury and investigate our world. They are, respectively, the depletion of resources and the production of pollution.

2.4

Changes occurring

The changes occurring when resources are used up by our activities may be inert or damaging ones. It is not particularly important for the future of the Earth, for instance, if all the coal or oil is extracted from the ground. It may well be important for the survival of humanity, which is what is usually meant when the survival of the Earth is discussed, but the presence or absence of these particular materials will not affect the survival of the remainder of its inhabitants. On the other hand, if the resource used up is oxygen, or pure water or the vegetative cover, then a different conclusion would have to be drawn. True, the barren planet would continue to rotate around the Sun (until that source of energy disappeared), but the remainder of the living ecosystem would be altered so drastically that no stable conditions could be expected to remain. There may be a reinvention of evolution once the system had stabilised again, but whether that evolution would bring about the existence of animals or human creatures is by no means certain.

2.4.1 Pollution The other major effect, that of pollution, can sometimes be a more serious matter. When unwanted items are discarded on the surface of the Earth, their presence there tends to be forgotten. The end result of their being jettisoned, though, may be harmless or serious, depending on their nature. In the main, any substance derived

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15

from a natural source, without chemical treatment in its production, will bring about no physical harm to the Earth (though it may be objectionable to view), but a chemical treatment will, on the whole, make the discarded object harmful. Thus, a piece of wood thrown into a field will fairly quickly decompose back to organic products that can be absorbed into the soil with no ill effects, but a piece of plywood or paper made from wood that has been treated with resins or bleaching and printing compounds can contaminate the soil (* L-2) (see Table 1.1 for explanation of codes) with the resultant decomposition products. Any chemical substances thrown away can have a range of undesirable environmental effects. First, they may leach into the ground where they are dissolved into the subterranean water and hence reach streams, rivers and springs, from which animals (including humans) get their drinking water. A steady diet of these compounds is not recommended for healthy existence and can indeed accelerate the mutational changes by which a species evolves. The probable consequence, though, is for evolution to be retrogressive, rather than advantageous. The second problem is much more tangible. The use of chemical compounds can quickly lead to the destruction of the soil crumb structure. Soil particles become finer and can be washed or blown away as dust in rainy or windy weather. The topsoil, in which most of the nutrients are stored, is then lost, making the ground less fertile. This increases the need for artificial fertilisers, which then compound the erosion problem. Finally, the chemicals applied in this act of compensation can blow about during application, to be inhaled by any local population, causing health problems that may, in the worst-case scenario, be fatal. Crops not destined for treatment can also be contaminated (and hence damaged or even destroyed), though geotextiles now available can help to prevent this problem and can also restrict to a considerable extent the occurrence of soil erosion.

2.4.2 Side effects Harmful human activities do not consist exclusively of discarding chemically modified consumer goods. In our wish to survive, acquire, explore, conquer and so forth, we produce a wide variety of other side effects, too numerous to describe in detail. Suffice it to say that the end results of our actions in producing or using energy, medical products and agricultural crops, or in excessive hunting, overfishing and destruction of forest cover, tend to be entirely negative from the viewpoint of global health. While we continue to replace land by buildings, roads or other of the appendages of our ‘civilised’ way of life, we can expect to bring about a loss of free space and hence a loss of habitat for animals and a loss of species diversity. If we add to this noise or visual pollution, then we induce terror, behavioural changes and possibly even physical damage into the equation, not to mention a reduction in aesthetics that can bring about emotional distress. Our electromagnetic onslaught, compounded by excess power use and by the current state of information overload to which we subject ourselves may, according to

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Environmental impact of textiles

some experts, cause other physical changes, such as damage to the brain, that will not improve our existence. Add to these problems the effects of compounds released to the atmosphere. Gases that are poisonous to humans or that remove oxygen can bring about drastic harm to individuals, either directly or by increasing climate change effects, such as global warming, tornadoes, floods, and so on. Liquids or gases discarded may also be toxic (* A-2, W-3) to animals, plants and fish, as well as to human beings. Oily liquids can change flotation properties of birds or can be carcinogenic. Detergents may alter the balance of aquatic species. Toxic solids at microscopic size (* L-2) can impede breathing or stunt plant growth. Thus, water damage, biodestruction and other effects can be devastating to the Earth’s health. Here again, textiles are invaluable aids in many of the filtration systems used to minimise the spread of pollution. Finally, there are the other actions of human beings that must be tolerated by the ecosytem. Outbreaks of fire, accidents, explosions of bombs and dust production from such events as erosion or blasting operations are all likely to have some adverse effect on planetary health and hence on our survival. Clearly, there is much more damage caused to the Earth’s health than that from the actions of the textile industry, even though the industry has some part in many of the causes of harm described above. In particular, it should be noted that textiles intended to provide protection against environmental problems may bring about such problems during the course of their manufacture. However, no quantitative or even qualitative survey has yet been carried out of what blame can be squarely attributed to the textile industry, in contrast to the blame allocated to the industry solely as an auxiliary operation connected to some other cause of harm. It is time to take a closer look at what real problems the industry can legitimately be accused of causing.

3 The nature of textiles

3.1

Properties

Before trying to get any idea of how textile production can affect the environment, there are some basic facts that have to be recognised. These stem mainly from the nature of textile materials themselves and bring about the need for special consideration that is not always realised by people even closely involved in the industry. The first fact that needs to be accepted is that textiles are unusual. This may seem strange at first, considering the number of pieces of cloth, strands of yarn or fibre bundles lying around in every corner of the planet, but, despite their ubiquitous nature, textiles are an extremely odd type of substance. To be useful, they have to combine a wide range of properties, such as adequate strength, high flexibility, the ability to accept many different chemical treatments, optical, thermal or electrical characteristics of a variable nature as desired by the user and ease of maintenance. It is difficult to imagine any other engineering material that could achieve half of these necessary attributes.

3.2

Textiles as engineering materials

It is important to appreciate that textiles are indeed engineering materials in the true sense of the term. A textile product is manufactured by carrying out a range of treatments, which may be any combination of mechanical, chemical or physical in nature, just as happens with any other engineering material. The difference in textiles lies in the basic starting unit, the fibre. Fibres, though, are not typical engineering components. If you compare a fibre with a metal rod, a wooden beam, a slab of concrete, a brick or any other solid material used in engineering applications, there is an obvious difference. If any of the other solids are pushed, they move away in the direction of the push. A push on a fibre, yarn or fabric, though, does not move it away in a simple straight line. It makes it distort and fold up on itself. This is the basic cause of the difficulties that have existed in the manufacture of textile materials throughout history. 17

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Environmental impact of textiles

The problem is two-fold. First, because the fibres, yarns and fabrics have such low rigidity, it is not possible to put them into a specific position and expect them to stay there. As soon as they are left unsupported, they will collapse under the influence of gravity, even if there are no more forces acting on them, and lose the shape they had before they were released. Second, the basic unit is so small that it is impossible to work with individual components of textiles. It is necessary to operate, literally, on thousands or even millions of fibres at a time. Each of them will behave in a slightly different way from what might be expected when considering the forces acting on it. This creates problems of a special kind. The solutions that have been adopted over thousands of years of textile production all have in common the fact that operations are carried out on the fibres in large quantities in a manner that attempts to control most of them, while accepting the inevitable need to recognise that some will behave in an undesirable way.

3.3

Principles of textile manufacture

For the reason noted above, the machinery needed to produce textiles cannot be simple. Few portable pieces of textile production equipment exist today, with the exception of hand production equipment such as knitting needles, embroidery frames, looms and drop spinning equipment still used by craft workers or indigenous people. As a direct consequence of this, in the vast majority of cases textile production equipment is massive, complex, expensive and difficult to use effectively in its aim of manipulating millions of tiny particles of flexible units at a speed high enough to satisfy the demand for its products. From the ecological perspective, this has two major consequences. First, textile production uses vast amounts of energy. The high demand and the large size of machinery forces the use of a lot of power in all parts of the world to keep the flow of materials going. Second, because of its complexity, the actual production of the machinery is environmentally very costly. The steel for stable framing, supports, protective covers, shafts, bearings and so on, has to be mined and refined. So too do the various non-ferrous metals used in reducing weight, improving electrical or corrosion resistance properties or providing more durable gears in the equipment. Plastic products used to enhance electrical, thermal or acoustic insulation have to be derived from oil, once it has been extracted from great depths below the surface of the ground or sea, by complex chemical reactions. All of these processes use energy, consume raw materials and produce waste matter as pollution discarded to the air, water or land once the intermediate product of the particular stage has been made.

3.4

Energy

As a result of this high environmental cost (and, even more of a spur, the cost of wasted energy), there have been many attempts to produce energy in less costly ways. The use of coal, oil, gas and electricity has been tried, in turn, over the 200

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years or so that have elapsed since the Industrial Revolution first introduced the use of power in textile production.

3.4.1 Coal Coal, the fuel that drove the Industrial Revolution, is rapidly disappearing from use for electricity generation in the developed nations. It creates too many problems, from those encountered during its extraction to those produced by its combustion. Miners working in risky underground locations are constantly in danger of mine collapse, fire, poisonous gases or lung problems and it is not unusual to read of major disasters in those places where coal faces are still worked. The residual piles of waste make a hideous mess of unsightly scars on the face of the Earth. Burning coal gives rise to smog or other atmospheric pollutants (* V-3, A-2, A-3) (see Table 1.1 for explanation of codes) and to health problems induced by breathing the toxic by-products resulting from the combustion of impurities in the coal. However, there are still coal-powered energy generation plants in operation in many parts of the world, to the detriment of our environment and the health of people living on the planet.

3.4.2 Oil The combustion of oil is currently a popular form of energy production. Oil itself is cleaner-burning than coal, but can cause major problems for the environment in its production. The oil wells that proliferate in those parts of the world where ‘black gold’ is extracted fill the air with fumes (* A-2) from the burning oil that appears at the top of each well. The scars on the land left after sinking a well are as ugly (* V-1) as those left by coal mining, and the pipes must often be sunk to a greater depth than these mines in order to reach the oil site. Drilling operations also produce ecological disturbances, from the displacement of wildlife and the arrival of unsightly equipment to the burning of the fuel used to power the rigs. When the oil is moved, too, the spills (* W-3) that are so common in our modern world can each kill or maim literally thousands of living creatures.

3.4.3 Gas For reasons of cleanliness and economy, many textile factories have adopted gas as the source of at least a part of their energy. Coal gas, the original fuel in this category, merely transferred the pollution from the point of use to the point of production, since it was manufactured by burning coal. It was also notorious for its toxic (* A-2) nature. More recently, coal gas has been replaced by natural gas, extracted from the ground along with oil, which is cleaner burning and not toxic. Unfortunately, gas of any kind cannot be carried around easily, so pipe lines or pressurised containers are needed to be able to make use of this fuel. It also has to

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Environmental impact of textiles

be refined to some extent to keep it clean and has an odour that can be objectionable to some people. More to the point, even if it is completely pure, it still produces considerable amounts of carbon dioxide when it burns, adding a significant contribution to the global warming problem.

3.4.4 Electricity All of this brings us to consider the most common source of energy in textile plants, electricity. At first glance, it is the ideal fuel. It is clean, convenient, versatile and has all those other attributes that we seek to make our lives easier. Examine the situation more closely, though, and a different perspective begins to emerge. All those benefits, it is true, are experienced by the user, but the way in which electricity is actually produced is far from ideal. It may be the result of burning coal or oil, with the drawbacks already mentioned. It can also be generated by burning all kinds of waste material, much of which is domestic pollution, with the consequent release into the atmosphere of carbon dioxide (* A-1) and even more undesirable substances created as by-products of the chemical combustion process (* A-2). In an attempt to give electricity generation a better image, modern production has relied heavily on hydroelectric generation techniques. These involve allowing a large quantity of water to flow from a higher to a lower level through a pipe in which turbines are caused to rotate by the rushing motion of the water. Apart from the need to produce the equipment, potentially an environmentally costly process in itself, there is often a need to create artificial height differentials so that the water has somewhere to flow from and to. This can mean diverting rivers or streams, building dams, flooding valleys and excavating tracts of land, ecologically expensive ways of providing a flow of water.

3.4.5 Nuclear power The proliferation of nuclear power plants over many parts of the world is an indication of how much promise this technique was once believed to have as an alternative means of producing energy. The unfortunate truth, of course, is that there are drawbacks to nuclear energy that were either not foreseen or were mistakenly assumed to be trivial. The first of these to surface was the difficulty in disposing of spent fuel. Nuclear fuel rods contain highly concentrated radioactive elements. Their activity cannot just be turned off once the fuel is spent. At the end of its useful life in terms of an energy source, there is still a dangerously high level of radiation left in the atoms of the radioactive element. This is not enough to make it possible to take advantage by generating electricity, but certainly enough to kill off a few thousand people by radiation sickness if it were to be left lying about (* L-2). The solutions adopted to overcome this drawback include reprocessing and storage, but these, especially the latter, remain problematic in view of the costs

The nature of textiles

21

involved and the risk of leakage over the enormous storage time needed. Even if the material is encased in concrete or stainless steel containers and buried in deep water, cracking or corrosion can occur, so that the nuclear waste (* W-3) can spill out into the sea. From there, fish and other aquatic life can become contaminated, or air currents, water flow and earth tremors can distribute the harmful material around the surface of the planet. Sadly, the radioactivity is likely to last for a much longer time than the encasing materials, so the results of our careless discarding of radiation are being bequeathed for future generations to inherit. A second side-effect has been brought to our attention in a dramatic way. Sellafield, Pickering and Chernobyl are names that conjure up images of nuclear power plants that went wrong. The latter, especially, taught us that one careless act at a nuclear plant can bring about a disaster capable of destroying the livelihood, and lives in many cases, of thousands or millions of people. The margin of error between nuclear fuel that reacts fast enough to create energy at a reasonable pace, and that reacting fast enough to blow its container apart, spreading devastation over the face of the earth, is not all that great. Even when the fuel cells are controlled properly, there are still undesirable consequences of the process. Electricity generation takes place because the nuclear energy heats water to steam, which is then used to drive turbines. The spent water is hot and has to be discarded somewhere, often into the nearest river or lake water. Although it has cooled down sufficiently to avoid boiling any nearby fish in the water, it is still warm enough to make the area uninhabitable for them (* W-1). Other species, both fish and plant, can take over and change the balance of nature in the region downstream of the plant discharge site. The consequences for the environment and for the people living in the area are not yet understood, but the changes already occurring as a result of this nuclear warming give us cause to reflect that our energy comes at a tremendous cost to our planet’s natural health.

3.4.6 New energy sources One consequence arising from our realisation of the risks of nuclear mishap is the effort to find new ways to provide energy. Solar, tidal and wind energy have all been proposed as ways in which electrical energy can be produced. The hydrogen cell has been suggested as a means of powering devices in place of intermediate electricity generation. At first sight, again, all these methods of providing supposedly unlimited energy seem impressive. They are natural, reliable (with certain fairly obvious limitations, such as location or time of day) and, more importantly, free. There will almost certainly be unexpected drawbacks, as the lessons of history have shown. Before we find them, however, there are obvious ones that can be predicted even without experiencing them, all resulting from the nature of energy supply. Energy production is complicated. The natural source has to be collected, harnessed, converted into electricity and distributed to its point of consumption. In

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Environmental impact of textiles

all of these steps, equipment is essential. This equipment, like that used to make textiles, is generally large, heavy, complex and made of many different materials, making it environmentally costly to produce. Its manufacture and operation produce pollution, because waste material is generated in the former case and lubricants are needed in the latter, contaminating the air, water or land. It also has a relatively short life, because materials subjected to heat and mechanical action from sun, weathering, water or wind will eventually corrode or suffer fatigue fracture. As a safety precaution if for no other reason, they will have to be replaced by new equipment roughly every 20 to 30 years, thus producing a continual environmental cost that never ends. More importantly, perhaps, is the mental attitude that will be engendered by the use of these ‘revolutionary’ energy sources. If energy is cheap (free?) and appears to be clean, then we should be able to use it in unrestricted amounts. We can waste it without any qualms of conscience and need not concern ourselves with the consequences of our actions, because neither the environment nor our pockets are being harmed in the process. It is only when we look at the entire cycle, from starting to make the power generation equipment to the end results of using it, that we can begin to realise how wrong our assumptions might be. The actual energy consumed in making or using a product is a minor fraction of its overall environmental impact, because the extraction of materials to manufacture the equipment designed to make the energy or to use it, and the pollution resulting from such extraction, must also be taken into account. Unlimited energy use means unlimited equipment production and hence unlimited ecological degradation. So the textile industry, like most others, is unlikely to find any sop to its collective conscience with respect to power consumption in the foreseeable future. Unfortunately, this is not the only way in which the environment suffers for the sake of the industry. Every stage of manufacture, from fibre production or harvesting to shipping, inevitably involves damage (considerable in some cases) to the environment. The following chapters will summarise how this damage arises, looking briefly at its consequences and examining the ways in which it can be alleviated. In addition, the way in which textiles can themselves be harmed by the environment in the process of degradation will be considered.

4 Textile fibre production

4.1

Scope of the industry

When the actual ways in which textile goods are made are put under close scrutiny, plenty of instances of environmental concern can be found. These will be looked at in sequence, following the various stages in turn, from growing or manufacturing the starting materials, the fibres, to the point at which an end product is shipped to the final consumer in readiness for use. First, though, the potential magnitude of any problem is examined briefly by estimating the size of the industry. An anonymous author1 records annual world production of textile fibres at about 60 million tonnes, of which over 50% is synthetics. This is in agreement with another writer,2 who quotes a value for world production of textile fibres of almost 58 million tonnes, with chemical fibres amounting to 31 million tonnes. Any growth likely to take place will probably be in the latter type of textiles; Schenek3 surveys comprehensively the state of natural fibre production and notes that, although the cotton harvest grew by almost 50% in the last few decades of the 20th century, the production of other natural fibres is likely to remain more or less steady. His estimate of total natural fibre production is in slight disagreement with the figures quoted above, since he records it at only about 26% of world total. Vishwanath4 presents an outline of the history of silk production, with figures giving details of the share from each country, quoting current production at 81 000 tonnes, worth $6.5 billion, and examining the factors that could determine whether or not production will increase from its present level.

4.2

Natural fibre production

Having gained some idea of the extent of production figures, the fibre-growing industry will be examined. As examples of typical raw materials, cotton (a plant seed-hair fibre), linen and the similar (bast) fibre jute, silk (an extruded animal fibre) and wool (an animal hair fibre) will be considered. Wool and linen almost 23

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Environmental impact of textiles

certainly predated the other two historically, but history does not have to be followed slavishly, so the vegetable fibres, cotton and linen, will be dealt with first, followed by silk and then wool before looking finally at the artificial (man-made) fibres. Other examples of each type of category exist, but their production techniques resemble those described below for the archetypal ones.

4.2.1 Cotton Cotton is grown on a bush, 0.6 to 6 metres high, in a field. Good growth of a high quality fibre requires a minimum of about 150 days of sunlight each year and plenty of fresh water. Cotton can therefore only be grown in a relatively narrow belt of the Earth’s surface, within about 35 degrees latitude of the equator, and in one or two other areas of the planet where local conditions are atypical for the latitude. The quality varies greatly in different locations, with Sea Island and Egyptian cotton generally considered to be the finest and Pakistani, Russian or Indian inferior. In order to achieve the optimum quality, efforts are usually made to enhance growth conditions. Fertilisers, insecticides and herbicides are commonly applied during the growing season. A considerable part of an international conference5 held in 1998 was devoted to this topic. Pertinent subjects discussed include enhancing quality by adjusting growth or soil treatment conditions and control of pests to increase yield. Daniell6 suggests that genetic engineering provides the best possible way of achieving both of these, since natural breeding has reached its limit because of species incompatibility and the small range of properties that can be incorporated into a plant by natural selection. This view is echoed by Wilson,7 who reviews current and future biotechnology, suggesting (among less fanciful ideas) the possibility of developing blue cotton plants to avoid the need to dye cotton for jeans. Although this may appear to be a good idea at first sight, it is appropriate to wonder how environmentally costly the process will be, both in the short term, because of the technology needed, and in the long run when different shades of blue are demanded by fickle consumers or when cross-fertilisation by wind distribution has eliminated all bushes bearing natural white cotton fibres. There is also the concern, a notable one at the moment, regarding contamination by genetically modified plants of other plants, not modified by this technology, in the vicinity. Other contributors at the 1998 Beltwide Conference, such as El-Lissy et al.8 give information about a scheme to eradicate insects, such as boll weevils or budworms, indicating that significant declines took place between 1995 and 1997. However, a conflicting note is sounded by Williams,9 who estimates that insect losses still represent 9.42% of the crop, the equivalent of 2.5 million bales of cotton and almost $1.5 billion dollars in financial losses. Many papers at the same conference deal with combination of biological and chemical controls to achieve sound management of insect pests, including aphids, leaf whitefly or sweet potato

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whitefly. Yet other contributors concentrate on soil tillage and methods of actually adding fertilisers to improve yields. Another important aspect of cotton growth is the need for a plentiful supply of water. Drought conditions can bring about a reduction in the quality of the cotton not only because of the lack of waterborne nutrient flow but also as a consequence of changes in fertiliser effects.10 For this reason, irrigation water must be pumped to the cultivation site if natural water supplies are insufficient for satisfactory growth. The chemical additives used have adverse effects on the land (* L-1, L-2) (see Table 1.1 for explanation of codes), as discussed in Chapter 2, and the need to irrigate the plants also brings about problems, though usually not quite such serious ones. First, unless gravitational flow can be harnessed, water must be pumped mechanically to the site, which involves manufacturing and powering machinery for the purpose. This machinery, like all the mechanical aids mentioned already, is itself environmentally costly. Second, the flow of water can exacerbate erosion and chemical leaching problems. Third, unless applications are carefully coordinated, the flow of water can remove some of the chemicals before they have accomplished their purpose, necessitating the application of more of them to control the growth of pests for which they are needed. Once the plant has produced its crop and the seed hairs are open, harvesting must take place. In these days, despite the fact that hand picking can yield a better quality of product, harvesting is almost invariably done by machine, simply because the cost of labour is too high to make the relatively slight improvement in fibre quality worth the extra cost involved. This machinery adds an environmental load to the process. The timing of picking, too, is less easily controlled when mechanical picking takes place. Manual methods can allow selection of just-ripe bolls to be made, but no machine currently in existence has this capability. Another conference, this time in Bremen,11 included details regarding the means for carrying out standard tests for measuring maturity, along with stickiness, dust or trash levels, fibre length and high volume instrument (HVI) testing. One method suggested12 for estimating the time at which cotton reaches its optimum maturity uses image analysis of fibre bundle tests. The next stage in cotton fibre production is the ginning operation, frequently taking place in the field in the immediate vicinity of the crop and designed to separate the cotton fibres from the seed fragments. Vizia and Anep13 claim that ginning is the weak link in cotton processing in India, because it suffers from poor efficiency and problems with cleaning and storage. They outline proposals for improvement in the future. Lugachev,14 in an effort to improve quality, has devised a new energy-saving technique for doffing fibres in sawtooth ginning by making use of a reflected air flow. Anthony and Byler15 are more optimistic on behalf of American producers; they suggest that careful control of the ginning process (especially in the matter of moisture uptake and machine type), together with a mechanism that includes computer measurement, improves fibre quality, gives higher yield and produces fewer short fibres and neps. The scheme they recommend

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is one in which moisture content, colour and foreign matter are measured by standard methods, after which this information is fed forward or back, so that ginning can be increased if necessary or omitted completely if it is not needed, thus providing better separation of seed-coat fragments with minimum fibre damage. These fragments are often regarded as useless but, in a notable example of environmental responsibility, Bader et al.16 use them for cattle feed and as replacement for pine chips in poultry barns.

4.2.2 Leaf and stem fibres Perfectly satisfactory textile fibres can also be obtained from other parts of plants than the seed hairs, notably the stem and the leaf. Stem, or bast, fibres tend to be less ecologically harmful than seed-hair ones. Linen, a typical example, can grow with virtually no attention or fertilisers, as long as water is available. Tarres17 discusses the cultivation of flax in the past and predicts how it might change in the future, also describing pretreatments and textile uses. Mackie18 carries out a similar task with regard to hemp, another stem fibre. For best quality fibres from both sources, a relatively small amount of care needs to be taken. The climate must be very moist but mild. The selection of optimum quality fibres has traditionally been done by hand in many countries. This makes the process more costly financially, but is environmentally beneficial. In recent times, though, mechanical methods of harvesting have been introduced, with adverse effects on the environment and a reduction in the quality of the fibre produced. Once harvested, the flax must be treated to release the usable fibres from the surrounding woody stalk and interior pith. The most important part of this process is the retting, or soaking, that allows slow decomposition of the woody parts to take place. Schulze19 notes the impact of flax fibre properties on spinnability. He investigates the performance of flax blended in turn with cotton, viscose, polyester and aramid components, finding that the importance of retting is paramount for successful yarn production. Traditionally, retting was done in pools or ditches, which tend to give a better quality of product, because the advantageous moist conditions are preserved longer in their shelter. If the flax plant is cut by hand and left to ret in the ditch, then the environmental load on the planet is minimal. Jute has similar advantages; Chattopadhyay20 outlines the retting process and describes the physical characteristics of the fibre, mentioning its chemical composition, sensitivity to alkalis and the need to take precautions to avoid yellowing if bleaching is attempted. Sadly, modern technology cannot accept such a beneficial solution. Dew retting or tank retting is more frequently used today, using mechanical devices to turn the stalks, maintain high temperatures and remove seeds. Lennox-Kerr21 reports the development of a new mechanical treatment process for flax to produce linen fibres that resemble cotton in their properties and structure and can be processed on equipment designed for cotton.

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4.1 Effect of pH on flax retting (source: see ref. 22).

Mechanical harvesting speeds up the cutting process and chemical agents reduce the retting time from two or three weeks to a few days or even less. Henriksson et al.,22 for instance, propose an oxalic acid-based system for chemical retting of flax that compares favourably with the more common enzymatic retting. Figures 4.1 to 4.4 (showing the effects of pH, oxalic acid concentration, sodium dodecyl sulphate concentration, time and temperature on retting) indicate that higher pH conditions bring about better retting, which is highly temperature dependent. The authors find that retting is virtually complete if treatment is continued at 75oC for as short a time period as a mere two hours. The presence of a detergent is needed to obtain satisfactory retting. Tests of tex, tenacity and elongation properties again indicate that the fibre can be processed on cotton production equipment. Although there are continuing arguments about whether the fibre quality is enhanced or reduced by the change from manual to mechanical or chemical processing, it is the economic aspect that really plays the most important part in the debate. The end result is, once again, a damaged planet.

4.2.3 Silk Silk production brings about a different set of considerations. The process involves rearing the silkworm grubs to the chrysalis stage, then unwinding the silk filaments from which the case enclosing this chrysalis is formed. Most commercially

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4.2 Effect of oxalate concentration on flax retting (source: see ref. 22).

4.3 Effect of sodium dodecylsulphate concentration on flax retting (source: see ref. 22).

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4.4 Effect of temperature and incubation time on flax retting (source: see ref. 22).

produced silk is of the cultivated variety, depending on feeding the worms a carefully controlled diet of mulberry leaves grown under special conditions. This need gives rise to the environmental costs of establishing controlled atmospheres and employing rigid growth conditions. Wild (‘tussah’) silk production, conversely, involves minimal interference with nature, so there is a great deal of interest in developing the fibre commercially. Akai23 surveys the available techniques, focusing on the main points of manufacture and on predicting the importance of commercial manufacture of wild silk in the 21st century. Jahagirdar24 feels that marketing is the main constraint, in view of the lower quality (compared with cultivated silk), but stresses that the fibre can provide a major source of income for millions of tribal people in India. Krishna Rao et al.25 agree, noting that the income is year round rather than seasonal, and point out that the forest cover is an easy source of food and plants, so constituting a base for commercial development. Ghosh26 describes improved techniques for enhanced quality and productivity and mentions the slow transition to better working conditions and higher incomes for workers, describing advances in powered machinery for reeling and spinning. In the context of this book, an important point is made by Nadigar,27 who notes that wild silk is exceptionally ecofriendly, since it uses no hazardous chemicals and encourages the socially beneficial activity of preserving the forests. He sounds a note of caution in that the dyeing and printing chemicals currently used are toxic substances (* W-3), but maintains that ecofriendly dyestuffs can readily be substituted for them. Shetty and Samson28 describe the production of silk without the need for traditional mulberry leaves, an obscure craft of tribal and hill

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peoples up to the time of writing, but suggest it as a potentially important commercial crop. Problems shared by all types of silk are brought to light in the literature. The first of these is the need to control reeling in automatic processing, a need that Hu and Suzhou29 discuss in some detail. Second is the importance of understanding the effects of cocoon shape or quality on filament uniformity, a topic reviewed by Singh et al.30 Maribashetty and two colleagues31 analyse why silkworms fail to produce satisfactory cocoons, dividing them into pathological, physiological, environmental and genetic reasons. They discuss abnormal development in the silk gland, spinneret and nerve malfunctions, and hormonal or disease causes, noting that control of both temperature and relative humidity is critical during the larval period. Cultivated silk, in addition, needs other special conditions. Selected mulberry trees are grown to act as homes for the silkworms and their leaves are hand picked daily. The trees, like cotton plants, require fertiliser and pesticide applications, though they tend to have lesser demands than cotton plants. They also have to be selected carefully, as the silk quality is highly dependent on the diet fed to the worms. One major problem that has emerged is the need to protect them from poisoning; Patil32 outlines the sources of contamination of mulberry leaves, describing the symptoms of poisoning (* A-2, L-2) by agricultural fertilisers, tobacco, factory exhaust gases and biopesticides, with a list of precautions to be taken in order to minimise the effects of these modern toxins. Thus, the carefully controlled conditions needed for silkworms to work their ‘miracles’ are environmentally expensive to maintain. Establishing the perfect atmosphere for the grubs needs a supply of clean air, apparatus to heat or cool to the correct conditions and power to operate the entire system. Extraction of the fibres by steaming to kill the silk chrysalis requires steam. The unwinding step depends on sensitive machines that are designed not to break the fragile threads. The cleaning process, necessary to prevent the newly wound threads from sticking to each other, uses hot water (often with detergents) to remove the silk from the gum, and the waste liquor is usually discarded to the ground water, acting as a pollutant (* W-3) once more. All of these components of the production process are environmentally costly. Silk, however, is not the only animal fibre grown directly or indirectly from insects; spiders can also produce a similar filament, though their ability has not yet been adopted with any commercial success because of the difficulty of unwinding the thread without breakage. However, there is one piece of work in this general area that deserves to be mentioned as it may represent the type of future development that can be expected in the industry. Smith33 notes that genetic engineering has enabled a Canadian company to insert a gene from a spider into the DNA of a goat so that the goat’s milk contains a spider silk protein that can be extracted and made into a filament with extremely high strength. Projected uses include medical sutures, vascular grafts, military and law enforcement protective clothing, structural engineering and packaging.

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4.2.4 Wool Wool is a natural animal fibre of a different kind, made from the inner fine hair of the sheep or goat. Again it is responsible for a new set of constraints. It is often advertised as the ‘perfect’ fibre, as a result of its desirable properties and is indeed at first glance worthy of that compliment. As we shall see later, though, its perfection is considerably reduced when its overall ecological impact is taken into account. Its production nowadays is complicated by a multitude of chemical treatments that add considerably to the environmental cost of achieving a fibre that is satisfactory to fussy modern consumers. The sheep is, admittedly, a beneficial asset to the planet. Not only does it provide us with the warm fabrics that have kept out cold climates since time immemorial, but it is also a source of meat. Unfortunately, the animals that provide the best wool tend to produce poor quality meat, and vice-versa. Sheep can thrive on marginal land where virtually nothing else will grow; the moorlands of northern England where these hardy beasts make their home have only to be seen in order to appreciate just how useful they actually are in converting scrub grass into vital end products. They also provide manure to fertilise the ground on which they graze or for sale to avid gardeners. Harvesting the wool consists of shearing the animal on a yearly or twice-yearly (depending on climate) basis. Hand shearing has virtually disappeared today, to be replaced by the use of electric shears. These do not consume a great deal of power, so are not too costly in environmental terms. But perhaps the most significant aspect of sheep growth, from the point of view of this book, is the use of sheep dip, an antiseptic agent, to prevent infection or to remove insects and other pests from the animal’s coat, which (depending on the exact formulation used) may seriously contaminate (* W-3) water supplies.

4.3

Artificial fibre production

The discussion so far of types of production has given a brief overview of most of the natural fibre concerns. However, natural fibres currently represent less than half of world textile production and we must turn our attention to the other major source, artificial fibres. These can be classified into three types, true synthetic polymers, regenerated materials and modified natural ones. Production figures for synthetic fibres during the year 2000 were quoted at 31.3 million tonnes,34 a figure that has been more or less constant in recent years; this should be compared with the world total of about 45 million tonnes if natural fibres are also included35 to give some indication of the disproportionate amounts of the two types in use nowadays. In the first two classes of artificial fibre types, the true synthetics and the regenerated ones, there are three main production techniques, dry (or solvent) spinning, melt spinning and wet spinning, details of each of them being found in

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standard books of textile technology. All of these have an impact on the planet that can be appreciated readily by an examination of what happens in each case. Before we look at these processes, though, we should consider the way in which a polymer is created.

4.3.1 Polymer preparation The usual, almost exclusive, source of raw material for polymer preparation is oil. As mentioned in Chapter 3, the extraction of this raw material is environmentally very costly and the production of polymers from it is not much less so. The oil is first ‘cracked’ (separated into various segments of a limited small range of molecular weights), usually with the aid of specific gravity or boiling point as indicator. The appropriate segment for making polymers is then converted into a form able to produce the starting material for the polymerisation step. This involves a chemical reaction between two precursors, often with heat, to produce a white solid that is then chopped up into chips for convenience in handling. The entire operation, as can readily be envisaged, uses large amounts of energy, produces waste in the form of gas, liquid or solid by-products (* A-2, W-3, L-2), and may often be quite a messy activity for the people engaged in it. Thus, the actual acquisition of the precursor for polymer manufacture is environmentally costly before any further processing is carried out. The chips that emerge are relatively clean and easy to handle, however, and can readily be passed on to the next stage, the actual fibre production step.

4.3.2 Dry spinning In dry spinning, a solution of the polymer in a suitable solvent is extruded, or forced, through a spinneret, a disc containing many fine holes through which the jet of polymeric liquid passes. The result is a set of multiple strands of filament, which are then drawn to strengthen them by means of a godet, a device exerting a force of traction on them. As the solution emerges from the spinneret and falls away from the solidification zone under the influence of gravity and the tension exerted by the godet, a stream of heated air is allowed to flow upwards around the newly formed filaments. This warm air increases the rate of evaporation of the solvent, ensuring that the filaments are stable enough to be drawn without breaking. The evaporated solvent is drawn upwards by the air stream, for collection and recycling. A paper36 describing the production of acetate from wood indicates that better absorbency and a closer approximation to the properties of silk can be achieved in this way; the paper describes in detail many aspects of the machinery needed and summarises the properties that are inherent in the fibres. Apart from the usual concerns regarding energy and complex equipment, there is an obvious pollution problem inherent in this method of production. No matter how carefully the operator may adjust the rate of air flow, it will be almost

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impossible to contain all the evaporated solvent within the system. In order to allow the filaments to pass down to the godet, there must be an exit aperture. If it is big enough to allow a solid filament to pass, then it will not prevent a gas from escaping. Even if the rate of input of air is very high, diffusion will ensure that not all the solvent vapour is swept along by the air stream. In the limit, the rate of flow of air needed to attempt to control vapour loss would have to be so great that the filaments would be blasted out of existence before they even reached the exit from the enclosed space, thus defeating the entire object of the technique. As solvents consist of harmful vapours from chemical agents such as acetone (* A-2), there is clearly a need for concern regarding the safety of the nearby workers, as well as that of the ambient surroundings in general.

4.3.3 Wet spinning In wet spinning, used most often in conjunction with regenerated fibres, a chemical reaction is carried out on the starting material to create a solution viscous enough to allow it to be extruded without disintegrating on leaving the spinneret. Immediately after extrusion, a second chemical reaction is carried out on the emerging liquid to convert it into a solid that can be drawn, as before, to form the polymeric filament. In this system, the presence of the chemicals, which may include acids, alkalis, reducing or oxidising agents and bleaches, may well pose a threat (* W-3) to environmental safety. In addition, the initial chemical reaction is likely to be a source of toxic or otherwise harmful agents (* A-2). All these chemical compounds need to be manufactured, again at ecological cost in terms of equipment, energy, raw material extraction and the various other cumulative factors encountered earlier.

4.3.4 Melt spinning Melt spinning, the final spinning method to be considered here, uses heat to melt the polymer, extrudes the resulting liquid through a spinneret, then immediately cools it to a solid form by means of a stream of cold air. Because the melting point of most polymers is not too far below the decomposition temperature, great care must be taken to avoid overheating the material. As these polymers are almost invariably poor thermal conductors, it is a difficult task to arrange for uniform melting to take place at a reasonable rate, without finding a mixture of still-solid chunks and blackened waste product in the apparatus. The risk is compounded if the rate of extrusion is not exactly right, since the polymer will then spend too long or short a time in the heating chamber, and may well clog the spinneret if production is halted to adjust anything. A further difficulty that may subsequently be encountered, applicable to all three of these production methods, is the need to dispose of a large quantity of waste if a careless operator makes a mistake and ends up with a mound of nasty stuff that cannot be used for anything.

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4.4

Alternative fibre sources

One development is the idea of using alternative sources for the starting point of manufacture instead of oil. An anonymous author37 describes the production of polylactic acid, a fibre that has the advantage (unlike virtually all other synthetic ones) of being biodegradable. This matter of biodegradability is extremely important, as will be discussed shortly, and the capacity to exhibit such a property has inspired other fibre research workers. Another anonymous writer38 suggests using a blend of natural cellulosic and thermoplastic polymers to yield a new fibre that can be blended with cotton, while a second paper39 in the same vein claims that a biodegradable polyester can be produced as a block copolymer with other units to give a material that can be used for most practical purposes. In both cases, though, the examples listed do not seem to belong to the type of compound that disappears into the Earth without trace. The usual problems with synthetic fibres that are supposedly biodegradable is that, when they break into tiny pieces, toxins resulting from their breakdown remain in the soil contaminating the surrounding land and hence water (* L-2). Better ‘biodegradability’ usually implies a faster rate of disintegration, but the increased surface area thus produced increases the rate of release of toxins and so makes the presence of these materials even more undesirable. The act of trying to recycle polyester, to be mentioned later, is suggested as an environmental cure, with a note that the efforts to carry out this type of operation for producing fibres are increasing rapidly.

4.5

Inorganic fibres

Another type of fibre that is becoming more important is in the inorganic category. Fibres of this type are produced from materials that are present in the Earth’s crust (or can easily be made from naturally occurring materials there) and that are inorganic rather than polymeric. Examples currently being used or considered as sources of fibre include glass, metals, carbon, asbestos and ceramics.

4.5.1 Glass fibres Glass, existing in a wide range of types for various end uses, is usually made by melting silica (the material of which sand is constituted) at very high temperatures and adding to the melt the necessary materials (oxides of various metals, etc., that impart the desired characteristics to the glass) before extruding the molten glass through a spinneret. Uses of the material are summarised by an anonymous author40 together with a description of the special machinery needs and mechanical properties. High temperatures always incur large energy costs. The extraction of the metal oxides from the ores in which they are present in the ground (plus their purification) is a matter for concern regarding the use of energy, the need for heavy extraction or refining equipment and the production of large quantities of pollution

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(* L-2). The process itself is obviously environmentally expensive and the slag heaps remaining after the metal oxides have been extracted can leave scars (* V-1) on the surface of the Earth that may take years to be assimilated back to provide any semblance of a harmonious landscape. The same factors also have to be taken into account in the production of metal fibres, since ores are essential as their starting materials. In addition, problems can be more serious, because their purification is usually more difficult than that of the oxide. Metals, too, need high temperature manipulation by complex heavy machinery that is environmentally difficult both to make and to operate.

4.5.2 Basalt fibres Basalt fibres made from rock solidified from volcanic lava are suggested by one author41 as an alternative to glass. Until recently, they were used solely in the form of basalt ‘wool’ for thermal insulation purposes, but the article describes new technology for making them into filaments. In comparison with glass, they are more stable to strong alkali, but less resistant to strong acids and can be used in the temperature range of – 200 to + 800oC. The filaments produced are apparently even enough to be used in normal textile structures. One suggested application is as sewing threads for fabrics exposed to high temperatures or adverse chemical environments. Thus, the ecological expense of producing these fibres, stemming mainly from the high temperatures needed in their production, is partly offset by their ability to resist heat, imparting a more extended existence in thermally degrading situations.

4.5.3 Carbon fibres The use of carbon fibres has only become widespread over the past couple of decades or so, but their growth has been rapid since their inception. Gurudett42 traces the development of a type of recently produced, activated carbon fibres, summarising their advantages over earlier ones and lists applications that depend in many instances on an improved adsorptive ability. Again, the complex series of processes and the inert atmospheres needed for carbon fibre production tend to make them expensive from the environmental standpoint.

4.5.4 Ceramic fibres Ceramics are the latest in a series of new materials earmarked for use as fibres. Many of them are oxides, with the same properties and drawbacks as mentioned above, but they usually have a very high melting temperature, which increases the difficulty of manufacture and hence the ecological impact. Others are chemically more complex, requiring difficult techniques of manufacture that are again unlikely

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to improve the Earth’s chances of recovery from their impact if production becomes as commonplace as is generally predicted by their proponents. A typical modern ceramic is silicon carbide, produced in one case43 by melt spinning of chlorine-containing polysilanes under an argon atmosphere, followed by crosslinking with ammonia as a curing agent, then subjecting this precursor to pyrolysis. This produces an Si–N–C system, with properties which the authors compare with those of the simpler Si–C fibre system. A second method of production44 involves infiltrating liquid silicon into carbonised wood at 800 to 1800oC. At 1600oC, rapid liquid infiltration occurs and the resulting ceramic fibre takes on the pore structure of the original wood, so that different properties are obtained when different types of wood are used as starting materials. From the descriptions of these two processes, it is clear that silicon carbide is an environmentally expensive fibre to produce. Apart from the high temperatures required, the need to produce polysilanes or silicon demands complex chemical reactions that place a huge demand on the planet’s capacity to recover from environmental stress, as also does the establishment of an inert gas atmosphere. Indeed, all these new fibres are ecologically very damaging in comparison with the more traditional ones. Their production is deemed to be necessary because of their highly unusual properties, such as heat resistance or their inert nature, which find invaluable applications in satisfying the demands of the space industry or the military that could not be met in any other way. Once again, it seems that the environment is being sacrificed to meet a need that would not be regarded in many quarters as strictly essential.

4.5.5 Asbestos fibres The fourth example of modified natural fibres, asbestos, has a special place in the environmental debate. Long regarded as a wonder material for its good thermal and electrical insulation abilities, it has been recognised as a dangerous substance because of its tendency to cause lung cancer (* L-3). It differs from the other materials in this group in that it does not need any heat or chemical reactions to produce it, merely a sequence of crushing and cleaning operations after it is dug out from the ground. At first sight, then, it would appear to be a desirable product, apart from its carcinogenic nature. Nevertheless, the equipment needed for these purposes is heavy, so that its use, even without its inherent danger, should not be regarded as wholly desirable. In 1999,45 acrylic sulphide was touted as a replacement for asbestos, because it is tough, resistant to alkalis, non-flammable and has high tenacity. It can thus be used as a filter medium for hot gases, as a reinforcing medium for concrete and in other applications where asbestos has been considered to be the only suitable material, as in firefighters’ uniforms, foundry clothing and similar protective garments.

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37

Microbiologically stable fibres

One direction in which research is making progress is in the attempt to produce fibres that are resistant to microbiological agents, thus prolonging their life and benefiting the planet. Jou and Liaw46 set down the conditions for a successful fibre of this type, pointing out that it should be non-toxic, non-allergenic, durable and non-carcinogenic and, if the antibacterial action is effective, it should reduce odour to make a safe, comfortable and healthy garment. Takeda47 claims to have developed such a fibre, with the incorporation of a tetravalent metal phosphate (such as titanium or zirconium), a divalent hydroxide (usually of copper or zinc) and a photo-semiconductor like titanium dioxide. Service48,49 describes Amicor, another new material based on an acrylic fibre, with the same type of behaviour, noting that the antimicrobiological agent can resist a wide range of bacteria, fungi and larger pests, such as dust mites, because it is incorporated into the matrix and can migrate from there to the surface to replace any agent lost by abrasion, weathering, and so forth during use. Stevenato and Tedesco50 make use of a new organic substrate with very fine particle size to provide effective antimicrobial activity without affecting fibre properties adversely. Rhovyl51 add an acaricidal (mite- and tick-destroying) agent to their fibre before extrusion to give long-term action in a fabric that not only destroys dust mites but also prevents subsequent reinfestation. Ward52 also suggests the premanufacturing insertion of an agent for mattresses and other bedding products.

4.7

Effects on the planet

Despite these attempts to increase longevity and safety, however, fibre production of any type is likely to be harmful to the planet in the long term. Costs of producing the fibres must include costs of making the chemical agents or precursors that are needed for growing or manufacturing them, costs of the chemical activity necessary for their production and costs of their handling or transportation around or away from the plant where they are made. These auxiliary costs are seldom, if ever, recognised, yet they exert a considerable influence on the planet that cannot be ignored in any comprehensive consideration of its long-term survival prospects. After the fibres are produced, of course, their adverse influence on the planet does not magically cease. There are still ecological costs that have to be paid. The next two chapters will consider what happens when they are made into further textile products in the form of yarns or fabrics.

References 1 2 3 4

Anon., Melliand Textilber., 2001, 7 (Sep), 156. Anon., Melliand Int., 2001, June, 84. Schenek, A., Int. Textile Bull., 2002, May, 8–17. Vishwanath, S., Int. Textile Bull., 2002, May, 20–21.

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5 Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999. 6 Daniell, H., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 595–598. 7 Wilson, A., Int. Dyer, 1998, 83(9), 35–36. 8 El-Lissy, O., Patton, L., Frisbee, R. et al., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 1001–1006. 9 Williams, M.R., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 957–959. 10 Mullins, G.L, Burmester, C.H. and Schwab, G.J., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 615–618. 11 Proceedings Int. Comm. on Cotton Testing Methods, Bremen, March 10–11, 1999, International Textile Manufacturers Federation, Zurich, 1999. 12 Schneider, T. and Rettig, D., ITMF, Proceedings International Conference on Cotton Testing Methods, Bremen, March 10–11, 1999, International Textile Manufacturers Federation, pp. 71–72. 13 Vizia, N.C. and Anep, G.R., Asian Textile J., 1998, 7(7), 68–74. 14 Lugachev, A.E., Tekh. Tekst. Promysh., 1998, 2, 19–21. 15 Anthony, W.S. and Byler, K., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 703–708. 16 Bader, M.J., Bramwell, R.K., Stewart, R.I. and Hill, G.M., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 1698–1699. 17 Tarres, X., Revista Ind. Textil, 1998, 360, 32–48. 18 Mackie, G., Textile Month, 1998, October, 47–51. 19 Schulze, G., Melliand Textilber., 1998, 79(5), 310–312 and E 77–78. 20 Chattopadhyay, D.P., Colourage, 1998, 45(5), 23–26. 21 Lennox-Kerr, P., Textile Month, 1998, October, 52–54. 22 Henriksson, G., Eriksson, K-El., Kimmel, L. and Akin, D.E., Textile Res. J., 1998, 68, 942–947. 23 Akai, H., Indian Silk, 1998, 37(6–7), 18–20. 24 Jahagirdar, D.V., Indian Silk, 1998, 37(6–7), 65–69. 25 Krishna Rao, J.V., Singh, R.N. and Singh, C.M., Indian Silk, 1998, 37(6–7), 79–83. 26 Ghosh, S.S., Indian Silk, 1998, 37(6–7), 51–52. 27 Nadigar, G.S., Indian Silk, 1998, 37(6–7), 71–73. 28 Shetty, K.K. and Samson, M.V., Indian Silk, 1998, 37(6–7), 21–25 plus 53–64. 29 Hu, Z. and Suzhou, J., Int. Silk Textile Tech., 1998, 18(5), 29–35. 30 Singh, R., Kalpana, G.V., Sudhakara Rao, P. and Ahsen, M.M., Indian J. Sericulture, 1998, 37(1), 85–88. 31 Maribashetty, V.G., Chandrakala, M.V. and Ahamed, C.A.A., Indian Silk, 1999, 38(3), 11–13. 32 Patil, C.S., Indian Silk, 1999, 38(3), 7–8. 33 Smith, W.C., Textile World, 2001, 151(2), 34. 34 Anon., Int. Textile Bull., 2002, March, 6–8. 35 Anon., Melliand Int., 1998, 3, 146–148. 36 Anon., Tinctoria, 1998, 95(9), 36–39. 37 Anon., High Perf. Textiles, 1999, March, 4101.

Textile fibre production 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

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Anon., High Perf. Textiles, 1999, March, 2–3. Takasago International, High Perf. Textiles, 1999, February, 2. Anon., Bull., Sulzer and Ruti, 1998, 36, 4–5. Anon., Textiles Mag.,1998, 27(4), 20–21. Gurudett, K., Man-Made Textiles in India, 1998, 41(8), 345–347 and 41(11), 481–485. Kurtenbach, D., Martin, H-P., Muller, E. et al., J. Eur. Ceramic Soc., 1998, 18(13), 1885– 1891. Greil, P., Lifka, T. and Kaindl, A., J. Eur. Ceramic Soc., 1998, 18(14), 1961–1973 and 1975–1983. Anon., High Perf. Textiles, 1999, January, 2. Jou, C.H. and Liaw, H.J., J. China Textile Inst., 1998, 8(4), 371–379. Takeda Chemical Industries Ltd, Med. Textiles, 1998, October, 2. Service, D.F., Chemical Fibres Int., 1998, 48(6), 486–489. Service, D.F., Revista Ind. Textil, 1999, 364, 49–56. Stevenato, R. and Tedesco, R., Chem. Fibres Int., 1998, 48(6), 480–485. Rhovyl, Med. Textiles, 1998, December, 2. Ward, D.T., Int. Textile Bull., 1999, 45(1), 44–45.

5 Yarn production

5.1

Starting material state

5.1.1 Vegetable fibres At the end of the fibre production process there are millions of tiny units, ready to be transformed into a yarn or some other type of fibre assembly in the next stage of the textile manufacturing operation. Their actual state depends very much on the type of fibre involved. In the case of vegetable fibres, the product is a dirty, tangled, contaminated mass that may contain a variety of plant or animal by-products. The former will be governed by the efficiency of selecting only fibres, rather than including other traces of the cotton, linen, and so on, plant in harvesting, or the number of local weeds infesting the area that have also been gathered. There may also be animal remains, either from insects that made their homes on the plant, or from larger creatures that were caught up in the harvesting process. Stroiz1 examines various types of contamination on cotton fibres and associates them with geographic location, pointing out that significant differences can arise for other than obvious reasons. Peters and Söll2 outline a new scheme for the automatic determination and removal of trash from cotton. Figures 5.1 and 5.2 show how the trash and dust contents are reduced between sliver and yarn by use of the technique.

5.1.2 Wool When wool is considered, more or less the same animal life residues can be expected, for similar reasons, but the vegetable content will represent the remains of grass, twigs or other plant fragments which the sheep has picked up before the shearing operation. There will also be considerable amounts of grease, since sheep exude a fatty combination of organic compounds in the form of a substance known as wool wax. Ryder3 examines the properties of this grease in detail, finding that its presence protects the sheep’s hair from drying out and reduces damage to it from 40

Yarn production

5.1 Reduction of trash content from sliver to yarn (source: Zellweger Ustar).

5.2 Reduction of dust content from sliver to yarn (source: Zellweger Ustar).

41

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weathering, sunlight or rain. It also delays the passage of water through the sheep’s skin, in either direction, and is instrumental to some extent in killing bacteria. Nevertheless, its presence in wool fibres intended for use in textile articles is undesirable and it must be removed; it is, however, described by Ryder as a valuable commodity in its own right.

5.1.3 Silk Silk, in keeping with its luxury image, is altogether a different matter. The fibres, lovingly produced by pedigree worms and cossetted by caring hands, are much cleaner in nature. They make their appearance in the form of a skein of fine fibres (although they may previously have been washed or scoured to remove the silk gum).

5.1.4 Synthetic fibres Synthetic fibres which have never been anywhere near animals or vegetables are scrupulously clean of such contamination right from the start. They may, though, have been subjected to the whims of a careless operator, who has allowed them to overheat, or they may contain residual chemicals from the extrusion stage if they are regenerated, wet-spun or solvent-spun in nature.

5.2

Washing

From the foregoing discussion, it is possible to infer that some elements of cleaning are often needed before fibres can undergo further processing. Washing is the usual way in which this is accomplished, either with water only or, more often, with some form of detergent. Hickman4 reviews the washing stage in the production of cotton and its blends, including materials in the yarn or fabric state, as well as in the fibre stage. He explores the history of cleaning, with an examination of energy, water, steam and labour requirements, and feels that all of these are reaching their limiting values. For this reason, he predicts that the time is ripe for closed water systems as a likely area for imminent innovation. Ripley and Ripley5 suggest that lasers can be used for cleaning and to enable the removal of trash to be accompanied by a bleaching operation, thus reducing a step that can be costly both financially and environmentally.

5.3

Scouring

When more severe cleaning is necessary to remove, for example, persistent dirt from cotton, then scouring is adopted. In this process, an additional agent is added to enhance the cleaning operation, sodium hydroxide being the traditional substance

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used. Lately, the disadvantages of this chemical, both in harming the fibres and in producing environmental contamination (* W-3) (see Table 1.1 for explanation of codes), have been recognised and other approaches have been tried. The most common of these is the addition to the wash liquor of an enzyme, a natural product that is less harmful to the environment and able to bring about cleansing more effectively as well as more rapidly. Section 1 of the Appendix describes some of the many variations of this treatment currently in use. In the case of wool, an alkali is also commonly added to aid in the removal of the greasy matter (politely referred to as ‘suint’), and Section 2 of the Appendix deals with the use of a number of additives used to improve the action of this type of treatment. Even silk has received some attention in the attempt to improve the environmental load of scouring. Krasowski et al.6 recommend the adoption of ultrasound to degum silk, in conjunction with standard degumming methods such as the techniques using Marseille soap, tartaric acid or papain. They report a significant increase in the mass of impurity material removed, with no obvious harm done to the filaments. Some vegetable fibres can suffer from the presence of gum that has to be removed. Bhattacharya and Das7 degum ramie with sodium metasilicate, alone or with other alkalis such as sodium carbonate or trisodium phosphate, instead of using sodium hydroxide. They determine optimum conditions, evaluating the performance of a trial by weight loss, whiteness index and colour strength of the degummed fibres. The new technique is so much better than the older one that bleach may not be needed in many cases, fibres also being much more lustrous and soft. Because the cost is comparable, there is obviously potential for commercial application, as well as for environmental benefits. The conclusion to be drawn from all this work is clear. This cleaning process is responsible, especially in the case of wool, for a serious assault on the environment. The effluent liquors from the plant have often been allowed, until relatively recently in the West and on a still-continuing basis even now in some parts of the world, to flow into rivers without any effort to treat them. The range of chemicals can be extensive and may include toxic, corrosive or biologically modifying reagents (* W-3). As can readily be appreciated, the enormous scope of the textile industry, and the need to remove some kind of impurity from virtually every fibre produced, have been of great concern to environmentalists over many decades. Unfortunately, there is little that can be done to avoid the problem, as we will see later, because most efforts to reduce the damage only lead to an alternative category of pollution. The only real solution is to avoid carrying out the washing or scouring in the first place, but this would inevitably lead to a product that would be totally unacceptable to consumers. Thus, even if a textile manufacturer exerts the utmost care, there is little hope of creating an effluent from the cleaning stage that can be discharged into the local water system without treatment. The types of treatment used and the relative effectiveness of each one are discussed in Chapter 9, Section 7.5.

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5.4

Bleaching

Often, the steps described above are insufficient to bring the fibres to an adequate state of ‘cleanness’ (defined in this instance as whiteness) for consumer satisfaction. In such cases, yet another process must be added, that of bleaching. This consists of a chemical reaction between a reagent (usually an oxidising or reducing agent) that destroys the molecular bonds responsible for the pigmentation that is the source of the coloured, or off-white, state of the fibres. It can be carried out at various points in the manufacturing process, from fibres to fabrics, but the principles of the reaction are identical no matter what the state of cohesiveness of the fibres. Thus, they will be discussed here, at the earliest point in the production line where bleaching can normally take place.

5.4.1 Chlorine bleaching Bleaching can be used for any fibre type, but is not often needed for synthetic ones unless they are blended with natural ones. Traditionally, chlorine has been preferred as a bleaching agent. Huikma8 describes its use, with an account of the effects on fibre and effluent properties of the various chemicals used. He also considers the possibility of reducing liquor ratio and enhancing safety factors, both important in ecologically driven manufacturing, and provides the diagrams shown in Figs 5.3 and 5.4 to illustrate the changes in pH, alkalinity, peroxide and fibre whiteness during batch bleaching. As can be deduced, there are problems with the use of chlorine. First, it tends to be extremely damaging to protein fibres, so that wool and silk are destroyed if left in contact with the reagent at too high a concentration or for too long a time. Second, of more importance from our viewpoint, chlorine is a major cause of environmental harm. The chlorine itself can be dangerous if ingested, can bring about skin irritation or disease on contact, and, even more critically, can produce very dangerous by-products (* W-3), such as dieldrins, during oxidation reactions.

5.4.2 Hydrogen peroxide bleaching Thus, much work has been aimed at finding an alternative means of whitening fibres. The earliest successful substitute was hydrogen peroxide, which, as well as being much milder in its behaviour to proteins, also leaves only water as a residue after reaction is complete. Gürsoy and Hall9 carry out a series of experiments designed to optimise hydrogen peroxide bleaching, in an effort to overcome its disadvantages of slowness and the catalytic degradation of cellulose in the presence of iron, nickel, copper, cobalt or lead ion impurities. They investigate the effects of a range of chemicals at different concentrations and arrive eventually at an optimum bleach recipe. Moe10 provides an overview of the mechanics of the bleaching detergents known as peroxyacids that contain hydrogen peroxide and a

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5.3 Changes in pH and alkalinity during batch bleaching; -----, pH; ––––, alkalinity (source: originally published in Textile Chemist and Colorist, Vol. 31, No 1, January 1999, pp. 17–20; reprinted with permission from AATCC).

5.4 Changes in peroxide concentration and fibre whiteness during batch bleaching; -----, % reflectance; ––––, H2O2 used (source: Textile Chemist and Colorist, Vol. 31, No 1, January 1999, pp. 17–20; reprinted with permission from AATCC).

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Environmental impact of textiles

bleach activator. These compounds are able to remove stains without affecting dyes (unlike chlorine bleaches) because the dyes inside the fibres are inaccessible to them; they are effective against such difficult stains as grass, wine, tea, grape juice and tomato-based foods, yet are compatible with enzymes or optical brighteners, and possess the useful attribute of being able to bleach dye colours produced on bleeding from one fabric to another.

5.4.3 Ozone bleaching Unfortunately, peroxide is very unstable, so can easily lose its effectiveness as an oxidising agent before the bleaching process is complete. A few ways of attempting to overcome this disadvantage are summarised in Section 3 of the Appendix. Ozone is also suggested as a potentially useful bleaching agent. Prabaharan and Rao11 stress that, in the ozone bleaching of grey cotton, moisture and pH level are both very important. They find that optimum conditions, with a compromise between best whiteness and minimum damage, are present at a moisture content of 24% and a pH less than 7, and provide details of the design of a suitable chamber. Figure 5.5 illustrates the effects of moisture content on treatment time and strength loss, both exhibiting a minimum value at about 32% moisture content. Figure 5.6 shows the effects of pH on whiteness, indicating that the value is constant at a pH below about 4.5, then diminishes slightly to pH 7 and subsequently falls off fairly rapidly as pH rises.

5.4.4 New approaches A more recent approach uses an activator, tetra-acetyl ethylene diamine (TAED), commercially sold as Warwick-T, which is recommended by several authors12–15 because it enables bleaching to take place more effectively under milder conditions. Yet another suggestion16 is to adopt ultrasound in the oxidative bleaching of wool to break down various bonds, so accelerating the effect of any oxidising agent used and giving increased whiteness in a lower time with no loss of chemical or physical properties. Lorenz et al.17 use the enzyme protease to bleach wool in an environmentally friendly brightening step, but find that the characteristic canary yellow of wool is not removed.

5.5

Carbonising

Yet another type of ‘cleaning’ (defined as removal of contamination in this case) often used with wool is the process of carbonising. This consists of adding concentrated sulphuric acid to wool, an action which destroys any cellulosic impurities rapidly but is not too drastically harmful to the wool if exposure time is kept short. Developments in the process include the application of a radiofrequency (RF) field to the wool, as described by Baltina et al.18 They claim that with RF

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5.5 Effect of moisture content on treatment time and strength loss in ozone bleaching of cotton;
, strength loss;
, treatment time (source: published in Color. Technol. 117 (2001), p. 100. Reprinted with permission from the publisher, the Society of Dyers and Colourists, Bradford, UK).

5.6 Effect of pH on whiteness index in ozone bleaching of cotton (source: published in Color. Technol. 117 (2001), p. 101. Reprinted with permission from the publisher, the Society of Dyers and Colourists, Bradford, UK).

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irradiation, wool can be carbonised at 100oC, instead of the more usual 120 to 130oC, thus reducing the tendency towards decomposition and yellowing, together with a reduction in energy use, while keeping acid concentration below dangerous (to wool stability) levels. Zanaroli19 suggests applying perchloroethylene to the wool to convert it into a more hydrophobic material and protect it from acid attack, so that the acid that penetrates and destroys the hydrophilic cellulosic impurities leaves the fibres unscathed. The solvent is recovered and recycled, an essential step for successful adoption of a new process in environmentally sensitive areas, though some solvent escape (* A-2) must be expected to take place. The same (Carbosol) process is also described elsewhere20 with the comment that it is not harmful either to the wool or (a claim that perhaps needs to be questioned!) to the environment.

5.6

Drying needs

The fibres need to be dried after cleaning in readiness to be moved to the next stage of production. If the drying equipment is immediately next to the washing or scouring plant, this is simply a matter of a conveyor belt, or its equivalent, to carry them the short distance necessary. This drying step requires large quantities of energy, as mentioned already, and may also produce impurities, such as vaporised solvent (* A-2), decomposition products (* A-3) from the leftover reagents present in small quantities, excess waste detergent and its by-products (* W-3), or other similar substances that are discharged into the air or water. The heat load produced at the outlet from the dryer must also be dissipated, usually by releasing it into the atmosphere inside or outside the plant, with consequent waste of heat energy and contamination of the surrounding area by the above-mentioned impurities. The same need for movement arises when the dried fibres have to be transferred yet again to another location for further processing. At some point, unless the plant is a mammoth one that carries out all stages in an enormous vertically integrated superfactory, there will be a need to transport fibres over a distance too great for them to be shifted piecemeal. Movement in loose form is difficult if not impossible, since fibres would be scattered widely if an attempt was made to ship them in this fashion. To achieve loss-free transportation of fibres in a suitably constrained manner, a baling process is normally carried out.

5.7

Baling

Baling is accomplished by using a large machine to squash down the fibres into a compact package that can easily be transported over long distances. Apart from the usual environmental costs of large machinery, there is little in the way of harm done, but this process represents the first significant occasion on which dirt and noise are a product of textile manufacture. As we will see later in this chapter, in parts of the process where they become more of a nuisance, these can be major

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sources of harm of a type different from any we have met to date, and can cause difficulties of an unusual kind for human beings, as well as for other species. Teutrine21 claims that there is a distinct tendency to move towards automation in baling, and forecasts a time, in the relatively near future, when the industry will insist on only one standard packing method to ensure that highly automated procedures for the opening of bales can be established. In readiness for baling, or indeed for any other stage in the manufacturing process, there is often a need to store the fibres or other textile goods. Because of their chemical nature, storage may occasionally create problems, either of disintegration from mould or other hazards (that will be discussed in Chapter 12) if there is too much moisture, or of cracking if the fibres are too dry. For instance, Brashears et al.22 note that various results produced at the harvesting step can change during subsequent storage in a way that can affect fibre properties and list the needs for successful use of storage conditions. Chun and Brushwood23 point out that storage in moist conditions can reduce stickiness in cotton, but that there is a limiting moisture content of up to about 15% that must not be exceeded if fibre properties (especially strength and reflectance) are to be maintained. Figures 5.7 to 5.9 show changes in strength and colour, sugar content or stickiness taking place as storage time is increased; clearly, it is the effect of moisture content, rather than the storage period, which has greatest influence on these properties.

5.8

Transportation

Textile materials have to be transported by vehicles during and after production. Vehicles are environmentally costly, but they also have a more sinister part to play in the planet’s degradation. Like textile machinery, they are large and complex, with the customary resultant costs, but there is also the matter of fuel combustion to take into account. Exhaust gases, whether from diesel or petrol engines, contain a multitude of harmful emissions (* A-1, A-2, A-3). Many of these are toxic or carcinogenic and compulsory legislation has been introduced in many parts of the world to ban some components (notably lead) by modifying fuel chemistry. Approximately half of all the air pollution today is caused directly by vehicle emissions24 and, although the textile industry is admittedly not responsible for all of these, it must bear a fair share. The exhaust gases that remain after removing (if this is possible) all toxic and carcinogenic products cannot yet be eliminated, and attempts are still being made to reduce their harmful presence by developing improved fuel economy of engines. This improvement, however, is being rendered ineffective as a result of tremendous increases in the number of vehicles being produced annually. The most critical emission gases, in terms of immediate damage, may include compounds of sulphur, heavy metals and organic by-products of combustion, all environmentally undesirable (* A-2). Even if these could all be removed by some miracle of science, the unavoidable production of carbon dioxide, a greenhouse

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Environmental impact of textiles

5.7 Effect of storage time on strength and colour of cotton (source: ref. 23).

gas, would still make the exhaust by-products a source of harm in the long term. Transportation also uses oil extensively, as a lubricant as well as a source of fuel. How harmful this substance can be has already been noted.

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5.8 Effect of storage time on sugar content of cotton (source: ref. 23).

Not only the shipping of goods, but also the transportation of people to and from work, has a contributory effect. Vehicles cannot travel without roads, whose establishment is a major cause of environmental difficulties, from the extraction of the raw materials to the mechanical devices used to lay them down. Their presence also eliminates land on which plants for food (or textile production) can be grown, or on which animals could graze, thus introducing a different category of environmental factor. The topic could merit a separate chapter (or even a whole book), but the fact that it is not exclusively related to the subject of textiles prevents more than a brief commentary at this point. However, its contributory addition to the net ecological cost of textile production cannot be ignored and should be borne in mind.

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Environmental impact of textiles

5.9 Effect of storage time on stickiness of cotton (source: ref. 23).

5.9

Opening

Once the bale reaches its destination, either in another part of the plant or after a longer journey, it has to be opened. The opening process consists of cutting or breaking the baling material, of metal or string, then beating the compacted fibres until they burst apart, sometimes in a near-exploding mass. Nakamura et al.25 define the purpose of an opener in terms of producing fine, uniform tufts and investigate the mechanism at this point in the opening sequence. They find that good tuft formation can have advantageous effects on processability and can

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improve yarn quality greatly. There is often a partial cleaning action accompanying this stage, as impurities are threshed out of the bales so as to be eliminated before the rest of the textile processing occurs. Large quantities of dust are likely to be produced in both of these activities and the surrounding air, in the worst situation, may be filled with a haze that obscures (* A-3) the light.

5.10

Carding

The next step in the sequence, carding, really starts to cause serious dust and noise problems. The potential for pollution can be envisaged from the report of a range of work in progress26 on non-wovens, concerned with carding, air-laying and hydroentanglement, in which a large quantity of fabrics intended for medical textiles, geotextiles, filtration and fluid transmission is concerned. An anonymous author27 provides a chart of cards currently available, with comparisons made of their performance, efficiency and quality of output product, while Merg et al.28 review previous investigations of fibre movement in the carding process. Carding machinery (usually referred to as carding engines) consists of large, complex equipment, with the usual ecological load, but the complexity this time also has the added drawback of making an enormous din and throwing off plenty of dust. The dust may be particles of fibre or may be the trash (waste substances left in contact with the fibres) left over after the partial cleaning of the previous stage. In addition, lubricating oils are often used to reduce this dust production, but these can then bring about their own problems. At some subsequent point, they have to be removed, since they would be undesirable in a finished product and carding oils are yet another undesirable load (* A-2, W-3) on the environment.

5.11

Blending

Blending, the mixing of different fibre types, may take place as an independent step or may be a part of the carding operation. It is carried out either by throwing the different fibre types up in a closed container until they are thoroughly mixed, or by passing them repeatedly through machinery that mixes them intimately by separating individual fibres and replacing them in a different position relative to each other. The net effect in both cases may include some dust production and some waste fibres that are thrown out from the fibre assembly, creating disposal or breathing problems (* A-2).

5.12

Combing and gilling

After carding and blending, fibres may be combed (usually for fine cottons) or gilled (for high quality worsted goods). These processes are essentially similar in nature, in that they both operate by the passage of a number of tines through the

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Environmental impact of textiles

fibre assembly to straighten it and to remove short fibres or impurities. Lubricating oils are used in many cases to prevent fibre breakage as well as to reduce dust. In the same way as those in carding, these oils are removed, becoming an ecological burden (* L-2, W-3). Considerable amounts of waste fibres may also be produced, though they are often recycled to make poorer quality goods. The now-familiar problems associated with large, complex machinery are again evident.

5.13

Drawing

The next step in the yarn production train is the drawing process. In this, thick fibre assemblies are pulled out to make finer ones, known either as tops, slivers or rovings, depending on their final size and (to some extent) the personal preferences of the observer. Essentially, individual fibres or groups of fibres are made to slide past other fibres so as to extend and thin down the rope-like structure in which they are situated. Drawing (or drafting, as it is often known) is usually achieved either by rollers that accelerate each part of the fibre assembly in sequence to bring about the sliding, or by some kind of tine insertion, similar to that used in combing or gilling, for the same purpose. In both types of drawing, energy is used, dust (* L2) and waste fibres may be created, and noise levels (* N-2) can be high, so that the step is the cause of environmental damage of various kinds.

5.14

Spinning

After drawing for one or more stages, the fibre assembly is ready for the last step in yarn production, spinning. This consists of three distinct operations, further drawing to thin the yarn out to the final desired size, twisting of the fibres together to give the assembly stability and winding up to keep the finished product tidily organised. One factor that should always be considered in regard to environmental aspects is that of moisture, because the availability of atmospheric water is crucial for successful spinning, producing better quality yarns that are not likely to be rejected. Price29 investigates the effects of relative humidity on the properties of cotton rotor-spun yarns and his work illustrates the importance of this matter. Several methods of machine spinning have been developed in modern times, the most common ones being the mule (now virtually extinct), ring, cap, flyer and open-end techniques. In all of these, energy is used, waste fibres or dust (* A-3) are produced, lubricating oils (* W-3, L-2) are used to reduce fibre losses, and considerable noise (* N-2) is generated, so involving once more the combination of financial costs with the environmental ones that are the subject of this book. In addition to the simple spinning of a yarn, twisting two singles yarns together to form a plied one is a common operation. The process of twisting uses machines with similar characteristics, as far as environmental costs are concerned, to those used in the initial spinning. So also does the texturing operation, in which yarns are given unusual characteristics that add interest by such steps as false twisting,

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crimping or the knit-deknit process. Each of these adds the extra environmental loading of another machine to the yarn production. Artune and Weinsdorfer,30 in producing a textured polyester yarn, additionally make use of a high-temperature heater to increase the speed of the operation by 20 to 30%. One noteworthy feature of twisting and texturing machinery is the extremely high speed of operation, which can cause very high noise levels (* N-2) and increased dust production (* A-3) compared with those of the spinning operation.

5.15

Noise and dust

Noise and dust are common problems. Both of them will appear again frequently, later in the book, but will be examined closely here. They both cause difficulties for human beings, as well as for the environment, but are distinctly different in nature from any factors so far considered, and as such should be given special recognition.

5.15.1 Noise Of the two, noise is the more difficult to classify with any quantitative accuracy. Noise can be defined as any sound which, because of particular characteristics (such as volume, frequency, speed or harmonic content), produces a sensation of discomfort or pain in the listener. The vagueness of this definition provides plenty of scope for ambiguity, especially in some of the more common sounds heard every day. For instance, the faint buzz of a mosquito in a bedroom, with its potential threat of blood loss, is a guarantee of a night’s insomnia, but for an entomologist, the sound of a mosquito humming to give away its presence may be like music to the soul. Music, too, comes into this category in its own right. The deafening rock music so beloved by some students is an anathema to many other members of society, who prefer to retain their hearing into old age. Similarly, the classical music enjoyed by the author may well be regarded as a special kind of torment by those same students. There are, however, some sounds that are undeniably and universally classed as noise. An explosion, a pneumatic drill, an aircraft taking off, or heavy traffic surrounding a car driving along a high-speed road with open windows, will always be so regarded, no matter what the acoustic tastes of the listener. There are two criteria that should be used in deciding where the sound fits into the desirable/ undesirable continuum used to establish a definition of noise: that of intensity (or volume) and that of ability to please. The two (as for students at a rock concert) may occasionally be in conflict, so that a sound which should be classed as noise because it is painfully loud may be acceptable because it stirs some deep inner emotional chord. Textile equipment can also be included in such a list. If the machine is running smoothly, with a quiet and steady, gentle hum, its sound might be regarded as pleasant by the engineer responsible for its maintenance. If its volume is extremely

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high, to the point where it is painful to the hearing, or if it is emitting a shrill, highpitched note, then pleasure disappears and excessive noise is eventually, if reluctantly, associated with its operation, even by the most dedicated engineer. The test of volume and frequency can thus be applied to any textile machine to determine its position on the noise spectrum. A measure of sound intensity, expressed in decibels, is used to quantify this property. The basis of the measure is an arbitrary allocation of 0 dB(A) as the intensity which is just barely perceptible to the healthy hearing of a young person, where the (A) suffix refers to a system of filters used in electronically weighting the measuring instrument to make its sensitivity comparable to that of the average human ear. As sound intensity rises, the measure increases and, again arbitrarily, the scale is defined in such a way that an increase of 3 dB(A) represents a doubling of volume. The net result of this allocation is that a sound intensity of about 30 dB(A) represents a comfortable conversational tone and one of about 140 dB(A) is loud enough to cause physical damage instantaneously to the ears of somebody exposed to it. In most industrial countries, the danger of subjecting people to high intensity sound has been recognised and legislation exists to limit the exposure time of workers. A typical example uses a derating scale, illustrated in Table 5.1, to define the time a worker may spend in an environment where high noise levels exist. From this can be derived the information that people are not legally allowed to remain in a noisy area at 90 dB(A) for more than eight hours in the working day, and may not be allowed to enter the area at all if sound intensity is 115 dB(A) or higher, with intermediate times being permitted at levels between these two. The legislation also includes the possibility of permitting exposure at higher levels if approved hearing protection is worn, although there are two problems with this loophole. The first is that brain damage can occur via skull bone transmission of vibration even if the ears are protected, which means that the only suitable protection should include a helmet with acoustic insulation incorporated into its structure. The usual hearing protection, earplugs, is useless in preventing harm, even though it meets the requirements of the law. The second problem is that of the machismo image. Because it is regarded by many textile plant operatives as ‘soft’ to protect their hearing, they simply refuse to wear the appropriate devices unless forced to do so by supervisors. So why spend such an inordinate amount of time dealing with the topic of noise? And why are we hearing more and more about the subject of noise pollution? Is it that we have begun to care about the quality of life, lowered by the unpleasantness of noise, or have we suddenly become concerned about the welfare of our workers? Have the level and quantity of noise increased drastically as a result of the modern development of larger, faster, or more complex machinery? There is considerable truth in all of these possibilities, but there is also another reason, much closer to the heart of the true textile manufacturer, the fact that noise costs money. The cost may be direct or indirect, but it is considerable and should be recognised as a genuine environmental reason as well as a financial one.

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Table 5.1 Permissible noise exposure Noise level dB(A)

Permitted unprotected human exposure time (hour)

less than 85 85–90 90–92 92–96 96–98 98–100 100–102 102–105 105–110 110–115 more than 115

No restriction 8 6 4 3 2 1.5 1.0 0.5 0.25 No exposure permitted

The direct cost concerns the nature of noise. It arises as a result of a process taking place in a machine. The process may be a small explosion, as in the internal combustion engine, or frictional contact between two surfaces in a gear train or other type of mechanism. Noise is a form of energy and as such must be generated from a power source. The electricity (or other type of fuel) used up in the process cannot then be harnessed to carry out work, so is wasted. Money is paid out to generate electricity, so the money used to pay for this waste is irretrievably lost from any chance of creating profits. As a final point, the generation of electricity is environmentally costly, and again the waste cannot be reversed. Indirect costs are more subtle. Work carried out in various industrial premises, including textile plants, has brought to light the suspicion that the hearing damage brought about by noise exposure can cause workers to suffer social harm. They may experience increased boredom and loneliness or become withdrawn from social contact as their deafness worsens. In some cases, they may blame the machines that have caused their deafness and deliberately take revenge by harming these perceived sources of a disintegrating lifestyle. Neglect of maintenance, slow correction of operating faults, or even deliberate sabotage, may occur in senseless acts of vengeance. All of these cost the manufacturer money and can exert a cost on the environment in the form of wasted energy or raw materials and excess exhaust gases. The noise that seemed to be of minor importance to our Victorian ancestors has become of crucial significance now that fuel prices have begun to constitute a noticeable proportion of a manufacturer’s costs.

5.15.2 Dust Dust consists of extremely tiny particles of solid materials that are produced when the larger units of these materials break into fragments as a result of mechanical, chemical or biological action. Because of their small size, they are easily blown

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about by air currents or may float in the air for long periods of time without settling. In textile production, they are of two types, the extraneous matter brought into the factory because of its contact with the original fibre sources (as packaging, for instance), and the fragments of the actual fibres themselves produced by the high forces exerted on them during the various stages of production. Once dust particles are released into the ambient air, their subsequent behaviour can cause a variety of problems. The most obvious one is the formation of an undesirable film on every surface in the vicinity. This necessitates frequent cleaning to keep the factory (or the house, because dust is also a domestic problem) looking neat and tidy, requiring extra labour. When the particles fall onto the moving parts of machinery, they can interfere with its successful operation, bringing about an increase in the frictional force between components or an increase in the viscosity of lubricants and, eventually, a breakdown if they are not removed by maintenance. If they fall on the product, of course, they can make it appear dirty, so that it has to be washed, or may even be rejected. All this brings about an additional burden on the environment, from the need to use either detergents, fresh lubricants or cleaning materials and from increased energy consumption. Significant increases in the cost of production can also be caused, a matter that may encourage some manufacturers to take the efforts to reduce dust production more seriously. The second type of problem caused by dust is its health hazard, mainly for human beings but also, to a lesser extent, for other species. Some types of dust are harmful because of their chemical composition, others merely because of their particulate size. Cotton dust, for instance, has long been associated with brown lung (* A-2), a degenerative disease of the pulmonary system in humans and animals, caused by chemical impurities in the fibres, usually with debilitating or even fatal consequences. Asbestos dust, which has a slightly larger particle size, has been shown to be responsible for lung cancer, purely (as far as is known) from the actual dimensions of the asbestos particles lodging in the lungs (* A-2), interfering with their function of cleansing the blood and themselves. Other, less harmful difficulties include the fact that wool dust can set up allergenic reactions and other types of dust can cause sneezing attacks, asthma and related diseases. Apart from any purely humanitarian concerns arising from these health problems, the increased absenteeism brought about as a consequence is, once again, of significance to the thinking manufacturer. Finally, dust can also interfere with the health of growing plants by coating their leaf surfaces (* L-2), so preventing them from absorbing carbon dioxide from the air and releasing oxygen back into it. For all these reasons, limits of permissible dust production are slowly being established in the industrial world and applied to textile processes. Chellamani and Chattopadhyay31 stress the need for workers’ health, to reduce fly and fluff production, and suggest control measures such as moisture addition, infrared lamps at strategic points, floating condensers, acid treatment of roller cots and use of overhead cleaners. Schmitz et al.32 measure dust levels in the German woollen

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industry quantitatively, distinguishing between respirable (total airborne) and alveolar (finely divided) dust. They find that the permissible limit of 6 mg/m3 of total dust is not exceeded in any part of the factory where their testing is performed and that new proposals to limit production to 4 mg/m3 of total and 1.5 mg/m3 of alveolar dust are achievable without any major effort. Van Nimmen and van Langenhoven,33 noting a sharp increase in contamination of fibres by foreign matter, such as plastics or wrongly coloured stray fibres, give an overview of proposed solutions to the problem, with benefits and problems of each one. Kuratle34 distinguishes between dust and trash for cotton, including in the latter term seed-coat fragments and all foreign materials not originating in the actual fibres (such as pieces of cloth, plaster or string), then suggests means of recognising them by optical techniques, followed by mechanical removal. Kechagia and Xanthopoulos35 describe new electronic devices that permit objective evaluation of such quality characteristics as dust or trash content in cotton, noting that their successful detection and removal are crucial in maintaining spinnability, quality, and hence the economic value of the products. We can see that yarn production can be a source of environmental problems from many angles. Human beings are a species that has consistently and deliberately, and to its own detriment, used oxygen to create carbon dioxide, in contrast to plants, which do exactly the opposite. If common sense is to prevail, we need to minimise dust production, as well as to deal with all the other undesirable ecological effects of yarn production as effectively as we possibly can!

References 1 2 3 4 5 6 7 8 9 10 11 12 13 14

15 16

Stroiz, H.M., Melliand Textilber., 1998, 3, 153–156. Peters,G. and Söll, W., Textile Horizons, 2000, March, 19–23. Ryder, M.L., Textiles Mag., 1998, 27(4), 14–15. Hickman, W.S., Rev. Progr. Coloration Rel. Topics, 1998, 28, 39–60. Ripley, W.G. and Ripley, D.A., High Perf. Textiles, 1999, May, 8. Krasowski, A., Muller, B., Fohles, J. and Hocher, H., Melliand Textilber., 1999, 86(6), 543–545 and E 144–145. Bhattacharya, S.D. and Das, A.K., J. Soc. Dyers Colourists, 2001, 6, 342–345. Huikma, W.S., Textile Chem. Colorist, 1999, 31(1), 17–20. Gürsoy, N.C. and Hall, M.E., Int. Textile Bull., 2001, September, 80–86. Moe, K.D., Textile Chem. Colorist, 2000, 8, 79–81. Prabaharan, M. and Rao, J.V., Color. Technol., 2001, 117(2), 98–103. Anon., Int. Dyer, 1999, 184(2), 17. Mathews, A.J. and Scarborough, S.J., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 732–734. Duffield, P.A., Mathews, A.J. and Turner, N.A., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 816–822. Holme, I., African Textile, 1999, June–July, 17–18. Quadflieg, J., Schafer, K. and Hocker, H., DWI Rep., 1999, 122, 544–549.

60 17 18 19 20 21 22

23 24 25 26 27 28 29 30 31 32 33 34 35

Environmental impact of textiles Lorenz, W., Heine, E. and Hocker, H., DWI Rep., 1999, 122, 509–513. Baltina, I., Brakch, I. and Vinovskis, H., Int. J. Clothing Sci. Tech., 1998, 10(6), 89–90. Zanaroli, P., Textiles Panamericanos, 1998, 58(6), 114–120. Anon., Tinctoria, 1998, 95(9), 70–75. Teutrine, D., Chem. Fibres Int., 1998, 48(5), 418–419. Brashears, A.D., Jahn, R.I., Bremer, J.E. and Valco, T.D., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 434–437. Chun, D.T.W. and Brushwood, D., Textile Res. J., 1998, 68, 642–648. Ross, R.D. (ed), Air Pollution and Industry, New York, Van Nostrand Reinhold, 1972. Nakamura, M., Matsuo, T. and Nakajima, M., Int. J. Clothing Sci. Tech., 1998, 10(6), 27– 28. Anon., Nonwovens Rep. Int., 1998, 329, 44–45. Anon., Int. Textile Bull., 1998, 44(5), 43–47. Merg, J., Seyan, A.M. and Batra, S.K., Textile Res. J., 1999, 69, 90–96. Price, J.B., Int. Textile Mfrs. Fed., 1999, 225–228. Artune, H. and Weinsdorfer, H., Int. Textile Bull., 1999, 45(1), 46–52. Chellamani, K.P. and Chattopadhyay, D., Asian Textile J., 1998, 7(11), 86–91. Schmitz, V., Schafer, K. and Hocker, H., Melliand Textilber., 1999, 80(7), 596–600 and E 151–3. Van Nimmen, E. and van Langenhoven, L., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 723–725. Kuratle, C., Proceedings Int. Comm. on Cotton Testing Methods, Bremen, March 1999, pp. 139–142. Kechagia, U.E. and Xanthopoulos, F.P., Int. Textile Mfrs. Fed., 1999, 143–146.

6 Fabric production

6.1

Traditional fabric production methods

Once the yarn has been produced, there are several ways in which it can be made into a fabric. The traditional ones include weaving, knitting and minor techniques such as crocheting, tatting, lace-making and net-making. In addition, fabrics can be made directly from fibres, without passing through the intermediate stage of yarn production. The oldest such technique is felting, but others have been developed in recent decades. These include non-wovens, fibre-to-fabric and film fibrillation. We have also seen the advent of newer techniques, such as laminating, needle-punching, bonding, tufting, stitch-knitting and braiding. Each of these can be examined in turn to assess any influence it may exert on the Earth’s health. In every case, virtually without exception, there is an involvement of mechanical action, creating the risk of dust production, fibre breakage and hence waste. In some of the techniques, though, particularly those carried out by hand, these drawbacks are minimal, solely because the mechanical action is considerably reduced by the slow nature of the process and the consequent reduction in highspeed contact between fibre assemblies and abrasive surfaces. The price paid for this reduction is, naturally, a much lower output.

6.1.1 Knitting Knitting machines are a relatively recent invention, dating originally from the 1400s and developed into a mechanical form in 1598, when Rev. William Lee first produced his replacement for the hand knitting that had been used up to that time. Whether it brought about an increase in attendance at his place of worship, because it provided his parishioners with more leisure time to enable them to take Sundays off, is not recorded, but it certainly improved the speed at which knitted goods could be produced. His work was subsequently improved until, by the middle of the 19th century, the circular machine was invented. In terms of environmental effects, the familiar factors of machine size and 61

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complexity, and of energy consumption, still exist. The need for a lubricant (* W-3) (see Table 1.1 for an explanation of codes) to reduce frictional contact between needle eye and yarn, thus reducing breakage (and hence waste), is also regarded as essential for today’s high-speed machines.

6.1.2 Weaving Weaving, the oldest of the techniques used to make fabrics from yarns, dates from prehistoric times. In those ‘good old days’ it was, presumably, possible to make goods without doing much harm to the planet, but making the same assumption today would be a sad distortion of the truth. Weaving no longer simply happens by shoving a yarn through two other sets of yarns previously strung on a frame between two trees. Nowadays, the warp has to be produced first, by using a winding operation known as beaming to place the warp yarns in the correct location on a beam in readiness for feeding into the loom. In addition, the weft yarns have to be wound onto a shuttle (or other weft insertion device) so that they can be threaded into the fabric in the correct sequence without tangling the entire system so badly that it cannot function. All of these steps require relatively complex machinery, with the associated environmental costs we have already met, and involve such factors as transportation between them or storage facilities that have to be added. Once these preliminary matters are arranged, the loom proper has to be set up in advance of its operation, with its yarns in the correct sequence for production, a process that can be lengthy and tedious. Operation in traditional looms is very damaging from the point of view of the planet and its inhabitants. Vast amounts of force are needed to hurl the shuttle repeatedly and reliably through the shed but, at the end of its travel, the device still retains almost all of the energy originally provided for its propulsion. This energy is then absorbed, with an enormous emission of noise, by allowing the shuttle to slam into a housing at the end of the race. As a consequence, the sound pressure level can reach 110 to 125 dB(A), making the weaving shed notoriously dangerous (* N-2) for the hearing of workers. Noise pollution, however, is not the only disadvantage to bedevil weaving. In modern looms, higher speeds are sought to enhance production rates, bringing about an increase in frictional contact between heddles and yarns and between adjacent yarns themselves. As the warp yarns are only moved in very small steps of progression through the loom, it is clear that they will suffer many such abrasive contacts before finally reaching the point at which they become embedded in the fell of the fabric. This brings about a great reduction in the fabric manufacture rate as a result of the need to keep stopping the machine to repair broken yarns, also increasing the amount of dust or broken fibres produced. In order to eliminate the rubbing, fibre breakage and dust production as much as possible, sizing is used as a means of lowering the effects of frictional contact. Sizing is the application of a size, or binding agent, onto the warp yarns, usually

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before they are wound onto the beam. The effect is akin to a glue that holds the fibres in place. The size may be made of natural materials, principally starch, or may be of a synthetic nature, made from polyvinyl or polyacrylic compounds. Sadly for the planet, neither of these two classes of compound can be allowed to remain on the fabric, because they are very stiff and create bulky regions in the yarns. These would not only be unacceptable to the consumer, but would also create difficulties in subsequent processing steps, such as dyeing or finishing. For this reason, they have to be removed in a desizing operation after the fabric is woven. This step is not easy to carry out, as the size is usually bound fairly firmly to the fibres in order to act successfully. Scouring or solvent extraction are used respectively to remove the two kinds of size and the by-products of these operations are an environmental hazard of the same type as those mentioned earlier in discussing scouring and solvent spinning. Water pollution is especially of concern, since the balance of aquatic species can be totally distorted by the presence of these substances (* W-3). In an effort to reduce pollution, Min and Huang1 describe a one-step design to desize, scour, bleach and mercerise cotton; they study the dyeing kinetics but find that dye absorption is not as good as with the conventional sequence of processes. As a result of these concerns, considerable interest has been shown in sizing and desizing operations. Stöhr2 notes that an ideal size would be one that could be reused repeatedly, indefinitely and without limitation, and deliver optimum sizing results. He feels that such a compound exists, developed in a manner that allows both the size and the water associated with the process to be recycled. The new material, coded as UCF-4, can be removed easily from the fabric with hot water, with no chemicals and reused as long as ultrafiltration is carried out to isolate its synthetic polymer molecules. Figure 6.1 compares the results of using the new size with those from more traditional ones, indicating that it has superior strength and elongation even though it possesses lower hardness. Reports of conference proceedings and of extended research programmes appear in the literature (see Appendix). When the need to remove the size arises, there are suggestions of how best to carry out this step, with enzymatic desizing appearing at first sight to be one of the most promising of these. Some of the relevant papers, both for sizing and desizing, are summarised in Section 4 of the Appendix.

6.2

Other methods

6.2.1 Felting In the methods of producing fabric without passing through a yarn-making stage, felting has to be considered first, not merely because it too predates history, but also because it creates major ecological difficulties in the modern manner of production. Felting occurs because wool fibres, with their sawtooth edge profile, can lock together under conditions of pressure, moisture, heat and agitation, to

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6.1 Comparative behaviour of UCF-4 and traditional sizes; (a) size film performance, (b) cost savings (source: ref. 2).

produce a dense, thick mat that provides an efficient thermally – or acoustically – insulating barrier. In modern machines the process is accelerated beyond the early simple one in order to reduce the time of production from days or weeks to a few hours. This is accomplished by the addition of detergents to the fibres and by the use of mechanical agitators plus superheated steam to enhance fibre contact and heating rates. The result is an unpleasantly hot atmosphere for workers in the production area, a waste of heat energy and an effluent that contains harmful substances (particularly detergent and fibrous matter) that have to be released into the water system (* W-3). As before, the large complex machinery and the high temperatures needed are both expensive environmentally, while the release of the chemicals in the effluent brings about secondary effects in the form of problems for species dwelling in the waterways.

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6.2.2 Non-wovens Non-wovens (often lumped together with fibre-to-fabric) is a term used to describe a number of similar techniques. All of them have in common the fact that they start from a bed of fibres, laid in a parallel, random or crosswise manner and then treated in some way to allow them to be held together in a stable lattice. Techniques for maintaining their integrity include using a glue (* W-3), using heat to melt some of the polymeric components added for this purpose or merely using high pressure to squeeze them together. Some may also use the felting of wool fibres as a binding device, though there must be at least 50% of the bulk in the form of wool to enable successful adhesion to take place. An anonymous author3 describes a spunbonding and spunlacing process using a single-step water-jet method, claiming that this represents an ecologically harmless cost-saving technology with minimum energy consumption, water circulation and downtimes, as well as providing good entanglement. Despite this claim, though, the usual hidden environmental costs are inevitably present.

6.2.3 Minor methods The remaining minor methods of fabric production may be divided into two categories, those in which hand production is carried out and those in which machines are used. Some of the techniques lend themselves to both categories, with a gradually increasing transition to the mechanical methods as old skills are lost by the attrition of the practitioners able to use them. Of the methods quoted, to the best of the author’s knowledge, only tatting is still carried out solely by hand, though embroidery (not strictly a fabric production technique) is done by hand in a slightly diffrent manner from machine embroidery. This technique is currently beginning to enjoy a renaissance, as described by Selm et al.,4 because it is ideally suited to production of the complex structures needed for certain medical implants. Techniques formerly carried out by hand but now converted to machine production, including net-making, braiding, crocheting and lace-making, all need the now familiar complex machinery that pervades the entire industry, with the inherent essential losses to the environment. None of the techniques uses any significant quantity of chemicals in the actual production equipment, though it must not be forgotten that the yarns, which are raw materials of each stage, have already accumulated significant ecological costs before the process begins. In addition, even the techniques carried out by hand need these raw materials and this should be borne in mind when assessing any advantages and drawbacks of a process. The issue of carrying forward a ‘debt’ is one that is often overlooked in attempting to produce an environmental audit. This is a timely place in which to consider the matter.

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6.2.4 Environmental aspects At any stage in a production train, there are factors that do not strictly belong to the step being considered. All the raw materials, for instance, are assumed to be present, as are the items of equipment needed to carry out the step. Nevertheless, each of these components has an environmental cost associated with it that should be taken into account if a complete evaluation of the step is required. The analytical procedure has been described in detail elsewhere5 and leads to a complicated process of iterative calculation that can trace the costs back to the initial step of extracting the minerals for the production of metals or polymers used in manufacturing the equipment from the Earth. Additionally, the costs of acquiring and using the sources of energy necessary to operate the machinery at all stages in the overall production train, from fibre and iron ore, to working equipment and yarns, can be derived. The net result is that no process is entirely free of environmental cost. If one is strictly pedantic, even the production of carbon dioxide by the people breathing can be considered an environmental cost, since this gas is an important source of global warming. When the need to provide them with food, housing, transportation, working space and all the other luxuries they use at the expense of the planet are also taken into account, it becomes more and more clear that human beings are a major source of environmental cost whether or not they even operate any textile operating machinery. The crucial point about this method of analysis is that, if the production at any stage is faulty, the cost to the environment does not just include that of wasting the product of the step where it is discarded, but also the entire production train up to that point. The later in the overall process a rejection occurs, the more cost to the environment is involved. Fortunately, this is a parallel cost to the financial one, leading manufacturers to try to avoid such waste by finding an alternative use for substandard materials instead of rejecting the goods totally.

6.2.5 Stitch-knitting The next production technique, stitch-knitting, is one which is never carried out by hand. There are several versions of the method, including ones with names such as malimo, maliwatt and arachne. In all of these, a layer of fibres is placed on a horizontal carrier plate and is then passed through a piece of equipment that is, essentially, a sewing machine. The machine places stitches into the fibre layer, holding the individual fibres together to form a loose, thermally insulating batt that is soft to the touch. From the environmental perspective at least, needle-punching may be regarded as a modification of this type of manufacture, since it involves the piercing of a fibre layer by barbed needles to bring about entanglement, but this time with no yarns in the needles. In all of these techniques, apart from the cumulative ones incurred and those resulting from the complexity and power consumption of the machinery used, there are normally no added costs to be debited specifically to the method of production.

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6.2.6 Coating and laminating Coating is usually understood to involve the application of a polymeric layer to the surface of a fabric, while laminating consists of the combination of two layers of material, previously produced by another method, by the application of a third layer in the form of a glue or binder. Both techniques are described in comprehensive detail by Fung,6 with an account of their newer methods of production and their many uses. Again, the machinery in both cases is large and complex, with the accompanying environmental costs. In addition, the bonding agent (normally some kind of polymer) has to be manufactured and heated, while the waste products are more than usually inconvenient as they are a combination of different materials (* W-3) that cannot easily be recycled. Bonding, in which the same kind of glue is applied to a fibre batt, has similar drawbacks in ecological terms.

6.2.7 Tufting Tufting, the major method of carpet manufacture nowadays, consists of the insertion of a pile yarn into a premanufactured layer of fabric. The machinery used, as may be expected when a large piece of fabric like a carpet is being produced, is very large in size, requiring high energy consumption and thus placing an environmental load on the planet once more. In addition, chemical compounds (* W-3) are applied to the system to stabilise the relative juxtaposition between the yarn and the fabric and heating is used to set this bonding agent.

6.2.8 Film fibrillation The final means of making a fabric, relatively new but increasing in popularity, is film fibrillation, a process described, for instance, by an author from the Kuralay Company.7 In this process, a polymeric film is produced by extruding the raw material in sheet form onto a flat bed, piercing it with mechanical or ultrasonic energy and simultaneously applying a high tensile force, in order to stretch the film rapidly in the crosswise direction at an unusually large rate of extension. As a consequence of this action and because of the high speed of application of the force, there is no opportunity for the energy applied to be dissipated into the layer and large numbers of local breaks occur. This gives the layer the appearance of a fabric, with many small holes interspersed throughout a continuous solid matrix. Clearly, the environmental costs incurred here, apart from the usual machine operation ones, will be mainly those of making the polymer, as already discussed when the production of polymeric filaments was considered in the Chapter 4. Thus we now have our textile goods in the form of fabrics, whether made via yarns or by a more direct process. Serra-Verdaguer et al.,8 looking at the whole picture, develop bases for eco production and finishing of textiles made from all natural and chemical fibres, and propose criteria for extending a labelling system,

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together with a survey of the main ecological aspects of fabric production and processing. The fabric itself is not yet ready for the consumer. A considerable amount of work must be carried out on it to make it acceptable to our modern tastes. The types of costs incurred by these subsequent treatments are the subject of the next chapter.

References 1 2 3 4 5 6 7 8

Min, R.R. and Huang, K.S., J. Soc. Dyers Colourists, 1999, 2, 69–72. Stöhr, K., Int. Textile Bull., 2002, March, 54–55. Anon, Melliand Textilber., 2001, 7(Sep) 228. Selm, B., Bischoff, B. and Seidl, R., ‘Embroidery and smart textiles’, in Smart Fibres, Fabrics and Clothing, Tao, X. (ed), Cambridge, Woodhead, 2001. Slater, K., J. Textile Inst., 1994, 85, 67–72. Fung, W., Coated and Laminated Textiles, Cambridge, Woodhead, 2002. Kuralay Company Ltd., High Perf. Textiles, 1999, February, 2–4. Serra-Verdaguer, J., Korner, A., Muller, R. et al., DWI Rep., 1999, 122, 579–584.

7 Fabric treatment processes

7.1

Starting material

Modern standards in textile use seldom, if ever, allow a fabric to be sold to the ultimate consumer exactly as it appears immediately after being manufactured. This greige state, as it is known technically, is unacceptable for various reasons and further treatments are required to bring fabrics to the point where they can be used. In modern mills, the foremost aim is to minimise the financial costs of finishing (and all other operations), so it is common for a plan to be drawn up to control the entire train. Arang and Fernandez1 describe a computer program aimed at management, with applicability throughout the entire factory and with emphasis on environmental protection. The treatments carried out after manufacture may be broadly classified as either finishing or colouring. It is also not uncommon for a fabric to need washing before attempting any other processing. Washing, either in detergent or merely in water, has already been discussed at the fibre stage, but may be used at various stages in the manufacture and should be considered as having the same potential means of bringing about environmental damage wherever it takes place.

7.2

Finishing categories

Once a clean fabric is available, the finishing treatment can begin. The type of finishing selected depends on the fibre content of the fabric and the end use to which it will be put. Finishing is usually divided into two types, mechanical and chemical. These can be distinguished by considering the way in which they are carried out. Usually, it is assumed that a treatment is mechanical if it only involves the use of some kind of mechanical action, but it is often accepted that the use of heat and moisture may also be a part of mechanical finishing. Examples of this category of finishes commonly adopted include calendering, beetling, fulling, decating, brushing, raising, shearing, moiré, shrink-proofing and steaming. Wool and synthetic-fibre fabrics are often considered to be the ones needing least 69

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finishing, because of their ability to be produced with many of the desirable features already incorporated. Wool cloths, though, are frequently given a range of both mechanical and chemical finishes, the mechanical ones of most interest being principally aimed at changing thermal insulation characteristics. Fulling is akin to felting and is achieved by subjecting the cloth to heat, moisture and agitation. Its purpose is to close up the tightness of the weave, so that the fabric retains heat better and is less likely to permit air to pass through and cause wind chill. As in felting, environmental costs result from machinery and energy factors, as well as from the discarded wash liquors (* W-3) (see Table 1.1 for an explanation of codes).

7.3

Mechanical finishing

7.3.1 Brushing, raising and shearing Brushing, raising and shearing are usually considered together; Korner2 explains the objectives and principles of the processes, together with discussion of the factors influencing them and the requirements for their successful operation. Brushing is, as its name implies, the passage of the fabric over a surface that brushes the fibres to lift them slightly out of the bed of the fabric. In this way, the amount of air enclosed is increased and, because trapped air holds heat well, so is the thermal insulation. Raising takes the process one step further, lifting the fibres still more by brushing them so roughly that the actual weave pattern is obscured. This not only increases insulating capability still further, but can conceal a sleazy cloth to some extent, so an open weave, with its inherently lower strength, can be disguised as a better one. Unfortunately, one side effect of this degree of raising can be an even greater reduction in strength, as the integrity of the fabric cohesion may be disturbed, thus shortening the life expectancy of the fabric. In such cases, there is another kind of environmental cost, that of the premature scrapping of the fabric, to add to the familiar ones of machinery and power consumption. There may also be a cost associated with the breakage of individual fibres, producing a certain amount of waste that cannot be reclaimed for any really valuable or useful practical purpose in view of the extremely short lengths of the fibre segments removed. After raising, the appearance of the fabric tends to be rather ragged, because of the rough treatment it has received. For this reason, shearing is then carried out. This is a means of cutting off some of the fibres, so that they are all at a uniform height above the fabric surface, by passing the cloth through blades resembling those of a cylinder lawn mower. The side effect, which is a large quantity of waste fibre, is obvious and produces an inevitable environmental cost.

7.3.2 Moiré In moiré finishing, in which a fake watermark is embedded into a synthetic fabric in an attempt to make it look like a silk, heat and pressure operations take place,

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with one portion of the fabric being forced to run counter to another by passage around suitably arranged cylinders, so that a frictional effect is produced that marks both of the contacting sections of the cloth. Decating, calendering and beetling can also be considered in the same category. Each of these treatments involves the application of pressure, with or without heat and/or moisture, to a fabric. The purpose and the fibre types to which the respective finish is applied are different, but the basic principles (and the ecological effects) are the same in each case. Machinery and energy factors are present once more and, when steam is used, some waste heat is evident when it is allowed to escape onto the cloth.

7.3.3 Mechanical shrink-proofing Shrink-proofing as a mechanical finish uses the overfeed principle, in which damp fabric is pushed onto the pin frame of a tenter (described in Chapter 11, Section 11.3) then subjected to sideways tensile stress while drying occurs. Energy losses are high, as described later, but the resultant fabric tends to be stronger and is less likely to be discarded. The fabric is also unlikely to be thrown away as waste prematurely, as it would be in the absence of shrink-proofing when a garment made from it might no longer fit after washing.

7.4

Chemical treatments

7.4.1 Chemical shrink-proofing Chemical treatments associated with shrink-proofing are normally used in modern plants and can be considered as the first example of a chemical finishing process. The mode of operation of such a process is to fill the interstices between the yarns of a fabric with a reagent that blocks the spaces so that the yarns cannot move into a closer juxtaposition. The process adopted may vary, either using impregnation with various resins, or by cross-linking with (for instance) dialdehyde, glyoxal and urea–formaldehyde. In both of these types of treatment, waste effluent of one or more of these chemicals (* W-3) is inevitable, and its subsequent discarding into the water environment will, just as inevitably, create a pollution problem. Xu et al.3 apply durable press to cotton in a one-step (and hence less polluting) method and compare the outcome to the more usual two-step process. They test results by crease recovery angle and strength measurements, finding that the two-step technique is better for crease recovery, but not as good for strength retention because of the longer curing times needed. These will, naturally, also increase environmental costs, offsetting to some extent the benefits imparted by this modification of the processing train. Optimum conditions for the two-step treatment are quoted as 4.3% citric acid and then 1.7% butane-tetracarboxylic acid. Cheng et al.4 attempt to improve the easy-care finishing of silk by using a multifunctional epoxide that reacts with the tyrosine in the silk to reduce the

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chemical activity of the fibre. Little or no change in wetting properties is evident, but the rate of hydrolysis in alkaline solution is very much lower after treatment. An anonymous writer5 reports the production of washable wool by easy-care finishing using oxidative or cross-linking techniques, noting that the process reduces shrinkage from about 30% to about 2%.

7.4.2 Water resistance A similar end result occurs in the various methods used to provide water resistance. The type of reagent involved depends on the degree of resistance needed, whether merely for protection against light showers, or against heavy storms, or to prevent all aqueous liquid entry in, say, a garment for protection against chemical or biological warfare reagents. In addition, there is considerable interest in the development of finishes that are resistant to liquid water, but allow moisture vapour to pass through. This treatment compensates to a considerable extent for the main disadvantage of traditional storm-resistant fabrics, the tendency for the people wearing them to be wetter from their own perspiration than they would be from the actual rain being kept off their bodies. The types of chemical used (and the resulting effect on the environment) vary, but are typified by insoluble metallic compounds, paraffin or waxes, bituminous materials, linseed or other drying oils and combinations of all these substances. Application in each case is usually achieved by padding, or passage through pressure rollers under or near the surface of the treatment liquid. Again, the inevitable machinery and energy factors must be accepted, but there is also the added problem of disposal of the chemical reagents. Paraffin and similar waxes are relatively harmless and can usually be reused easily, but some metallic compounds, oils and bituminous materials may be highly toxic (* W-3) and should only be released after considerable dilution. Even then, all of them are harmful in some degree and should be regarded as undesirable. In this context generally, the industry has begun to sound warnings. Lal6 expresses concern about the effects of pollution on the environment and Soljacic et al.7 propose that a system for ecoacceptable finishing ought to be developed. Gulrajani8 feels that the Indian chemical finishing system is already environmentally sound, but is antiquated. Mathew9 suggests that the use of ultrasound in all applicable wet processing steps, such as the preparation of sizes, emulsions, dye dispersions and thickeners for printing, would be beneficial to the planet’s well-being because it can reduce the amount of reagent needed. Duschek10 describes the mode of action of fluorocarbon polymers and the ability, by using a new technique, to apply such a finish in a lowemission manner (about 90% lower) to maintain emissions well below legislative standards and with no thermal after-treatment. How well the rest of the industry follows strictures for ecological responsibility is not too encouraging, as we will shortly see, but all the chemical finishes currently in vogue will be considered here first. In an unusual approach, Barton11 reports the

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possibility of ‘intelligent fabrics’ being developed. These would have fragrances, moisture, antibacterial finishes or thermal modifications incorporated into their structure to provide continuing effects. Until they are commercially realisable beyond the relatively few underwear applications presently available, the industry has to rely on more familiar techniques. Moisture vapour permeability, in conjunction with liquid water resistance, is currently ardently sought as a kind of ‘philosophers’ stone’ in textile science. The elusive ability to allow complete moisture comfort with the total exclusion of all liquid water and the total capability of perspiration moisture to escape, has not yet been developed. The principle on which a successful technique can be expected to operate is a simple one, the fact that there is a significant difference between the molecular sizes of liquid and vapour aggregates of water. Unfortunately, we do not yet have the ability to control the size of fabric apertures to the necessary degree of accuracy. The methods of approach currently in vogue include hydrophobic finishes, coatings, and laminations of microporous films or membranes. More details of the latter two are provided by Fung.12

7.4.3 Durability Hydrophobic finishes tend to suffer from a serious defect, in that the finish slowly disappears during extended use. Thus, a raincoat which gives adequate protection against showers when bought may, after a few laundering or dry cleaning treatments, be less than satisfactory and leave the unfortunate wearer soaked. In terms of environmental damage, the application of the water-resistant finishing agent, usually consisting of a reagent similar to those mentioned above in connection with liquid water resistance, is a problem both at the manufacturing stage, when the surplus chemicals are flushed into the drain (* W-3), and after use if the garment is thrown away prematurely because it is no longer of any value for its intended purpose. The type of finish will be governed by the degree of water resistance required, but all of those currently in use tend to be slowly lost with time and this approach is not now regarded as having any real future. Because of this, other solutions have been attempted. One of the earliest of these was the traditional oilskin often used by seamen and cyclists. This consists of a topcoat made from a fabric of cotton which has been saturated with an oil (usually linseed or some related substance) and heated to bake, and hence polymerise, the oil. The actual extraction of the oil, as with all oils, carries the environmental cost mentioned already, and the baking process is likely to produce toxic gaseous byproducts (* A-2) as a result of the high temperatures needed for polymerisation. The garment, too, is usually not completely satisfactory, as anyone who has cycled in one will attest. The inside of the oilskin after pedalling strenuously up a steep hill leaves the cvclist in a sad state of drenched discomfort from perspiration that stays with him, entrapped by the impermeability of the oilskin, for the remainder of the journey.

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7.4.4 Membranes The next type of solution to be discussed is the membrane, specifically described in a waterproof and breathable application by Bajaj;13 the technique is most familiarly typified for the general public by Gore-tex products. In these, a thin membrane of microporous material of polytetrafluoroethylene (PTFE) is sandwiched between two layers of fabric, usually polyester, to reinforce the fragile membrane and prevent it from shredding. The production step involves making PTFE and polyester fabrics, accompanied by all the usual difficulties in polymer manufacture, and in producing an adhesive substance to hold the layers together. The adhesive will impose an environmental cost, as will the subsequent process of applying it by machinery. The approach is not completely satisfactory, as the excellent barrier performance preventing water ingress is not accompanied by a total capability to allow perspiration to escape. In addition, the fabric itself can suffer from delamination, leading to premature rejection. The author has experienced both of these drawbacks, having used such a fabric and redesigned the construction of the sandwich material to minimise the latter problem, in a design for the surgical operating theatre gowns illustrated in Fig. 13.2. As always, prematurely discarding a product is an added load on the ecological equilibrium, so the use of this type of material in water-resistant garments is not to be recommended unreservedly.

7.4.5 Coatings A compromise between the techniques of using a microporous membrane and a finish is the adoption of coatings. In these, a microporous material is applied to the external surface of a fabric (usually polyester again) and is adsorbed directly onto the fibres. This method of production still depends on manufacture of the polymeric materials, but does not involve any separate adhesive, any separate application process or any risk of delamination. It has been shown to be more satisfactory from the ecological perspective. Steps are in progress to bring about further technical improvements to allow it to compete adequately on the basis of performance and financial factors. Kubin14 traces the development of coating technology and provides detailed information on recipes, process operation and properties imparted for a range of types.

7.5

Other finishes

A wide range of other finishes should also be considered. These may be categorised in the areas of treatment designed to modify the nature, appearance or feel of the surface for aesthetic reasons, those designed to lengthen the life of the fabric and those intended to provide enhanced consumer satisfaction. The first type includes softening, stiffening and antistatic finishes, while the second may be exemplified

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by abrasion resistant or antimicrobial finishes. The third category has become of much greater importance and includes such attributes as a built-in resistance to creasing, flame, oil and stains. It can be deduced that there is likely to be some form of crossover between advantages imparted by the three types.

7.5.1 Softening and antistatic treatments Softening and antistatic treatments both use the same type of reagents, such as quaternary ammonium compounds, to achieve their effect. These substances are manufactured in a process that has the customary environmental costs of chemical agent production. Application is seldom, if ever, completely perfect and quantities of the reagents are washed (* W-3) into the discard stream from the plant, affecting the local water purity. An anonymous author15 stresses the enormous need for softeners and discusses problems of sewability, yellowing and shearing stability that can arise from softener use.

7.5.2 Stiffeners Stiffeners, such as starch or vinyl compounds, need to be produced, either by extraction from cellulosic plant sources or by a chemical reaction and again are to some degree discarded in the waste stream (* W-3). A related type of finish is that of mercerisation, the process by which cotton is made more lustrous and stronger by short-term immersion in concentrated sodium hydroxide. The alkali is potentially an environmentally harmful agent if discarded into water or onto land (* W-3, L-2), so alternatives would be useful. Min and Huang16 provide details of a one-step process that includes desizing, scouring and bleaching as well as mercerising, but find that poorer dyeing results are produced by its application. Figure 7.1 shows the graph they derive for their cotton fabrics relating dye concentration (a) to dyeing time (t) on logarithmic axes. The colour level after a given time, but not the slope of the curve, is influenced by temperature, as may be seen in the diagram. Rathi,17 using enzymes, and Ramaswamy et al.,18 with simultaneous bleaching, also provide suggestions for mercerising, but imply no loss of properties as a consequence of the action. Figure 7.2 shows bar charts derived by the latter authors indicating the effects of bleaching and mercerising on dye uptake. Abrasion resistance is imparted by the application of some form of lubricating agent to the surface of the fabric. The substance chosen may be an oil, wax or a thermoplastic resin, with results and side effects comparable to those mentioned above in connection with these types of finishing agent. In extending fabric life by enhanced biological resistance, some consideration must be given to the hazards likely to be encountered by the fabric in use. There may, for instance, be a risk of insect damage, especially if wool fibres are present. If the fabric is likely to come into contact with the ground, or is to be used in a damp place, then the chances of rotting may be of concern. If it is to suffer long periods of exposure to the elements,

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7.1 Relationship between dye concentrations (a) and dyeing time (t) for cotton fabrics; dip temperatures:
, 20ºC; ∆, 40ºC;
, 80ºC; ¸, 100ºC (source: JSDC 115 (1999), p. 70. Reprinted with permission from the publisher, the Society of Dyers and Colourists, Bradford, UK).

especially where bright sunlight is present, then degradation by ultraviolet radiation is a possibility. Finishes have been designed for all of these and are frequently applied in the modern textile industry.

7.5.3 Microbiological-resistant treatments Resistance to biological agents, ranging in size from insects down to the smallest bacteria, can be introduced into textiles in the finishing process. Insect resistance is incorporated into a fabric by germicides (such as metallic salts), resins or organic mercury compounds, with the optimum substance toxic to the specific insect or mildew, and so on, being chosen to minimise damage in comparison with that suffered by an unprotected fabric. The most usual example of a harmful insect is the wool moth, which can degrade large quantities of fabrics by making holes in them. The moth operates by feeding on the disulphide links in the protein of the wool and has traditionally been combated by the use of dieldrin. This substance has been designated as harmful to humans because of its toxic and carcinogenic nature and is now banned in many countries. More recent techniques rely on less effective (in the opinion of many experts) substances, such as fluorides, compounds of antimony or chromium, dyestuffs (mitins or eulans) or formaldehyde to protect the wool (* W-3).

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7.2 Effect of bleaching and mercerising under various conditions on dye uptake of cotton fabrics (source: Textile Chemist and Colorist, Vol. 31, No 3, March 1999, pp. 27–31; reprinted with permission from AATCC).

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All of these compounds, from dieldrin to its modern substitutes, constitute a load on the ability of the planet to renew itself in a healthy manner. The chemical agents (especially the more modern ones, which must be used in far higher concentrations than dieldrin) can produce adverse effects in many species and are toxic to humans. Other insects, such as carpet beetles, are dealt with in a similar manner, with comparable results. The protection of textiles against insect damage is not without effect on the world around us, and the extended life of garments made from susceptible fibres (allowing them to be kept for longer periods instead of being thrown away as a load on the environment) should be weighed against the risks of danger or harm to the various affected species of the planet. An exactly similar argument also applies to rotproofing agents, such as metallic salts, condensation resins or cellulose acetate, which function in the same way to prevent damage by microbiological agents, such as moulds or mildew that are present in soil or damp locations. These treatment substances, which operate either by preventing contact between cloth and the harmful agent or by inhibiting microbiological growth, also create hazards to planetary species when they are discarded (* W-3). Efforts are made to minimise the amount of all of these reagents sent to waste, but the best processing conditions, unfortunately, can still bring about appreciable risk of damage from effluent chemicals. These smaller-scale undesirable biological entities have aroused interest because, if they cannot be removed, they can either destroy the fabric or can make it unacceptable, both of which lead to environmental stress as a result of premature discard. In general, the same types of chemical reagent have been used in the past to deal with problems on this scale as have been adopted for controlling larger pests.

7.5.4 Ultraviolet resistance Ultraviolet resistance is imparted to fabrics by protecting them with an agent that absorbs radiation in the relevant portion of the electromagnetic spectrum. Instead of attacking the chemical structure of the fibres, the incident radiation uses its energy to bring about an increase in the vibration of specific bonds in the absorbent molecule, thus allowing the fabric to survive unscathed. Once more, these substances (including amines, sulphonated or benzoyl compounds and other complex organic reagents) are unsafe (* W-3) if released into the water system and impose difficulties on ecological protection capabilities.

7.5.5 Easy-care finishes The third category of treatment purposes is that of consumer satisfaction (including protection). When it is of importance, easy-care finishes such as crease-resistance, soil or stain resistance or repellency and flame resistance are crucial. Crease-resistance depends on the application of an agent capable of allowing the fabric to retain a preset shape by ‘locking’ the molecules into a

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7.3 Bonding changes during crease-resistant treatment. (a) Original fabric with unstretched bonds, (b) crease in fabric; bonds stretched, (c) bonds broken chemically, (d) bonds reformed chemically in less stressed positions, (e) flattening of crease produces restoring stresses in bonds.

particular conformation, as illustrated in Fig. 7.3. The initial molecular structure is placed into the desired form (a crease, pleat or a flat surface, for instance) and a reagent (or its precursor mixture) selected from urea–formaldehyde, melamine– formaldehyde, epoxy resin or a vinyl compound, is spread onto the cloth. The combination is then heated to bring about the essential reaction, so that either the molecular interstices are filled by the polymerised substance or there are added cross-linkages formed between molecular chains. When a potentially creasing force is applied to the fabric in use, the resulting distortion of the fabric is resisted by the blocking action of the space-filling layer or the stretching of the bonds, and the set shape of the fabric is quickly restored once the distorting force is removed. Formaldehyde is a familiar carcinogenic agent, so that any residual amounts of this substance that remain uncombined with the urea and are discarded are dangerous on being released (* W-3) into the environment. In addition, the baking process can bring about the production of gaseous toxic substances (* A-2), released into the atmosphere as part of the emissions from the treatment process. Saraf and Alat19 address this particular concern with their paper on new developments in the search for alternatives to formaldehyde as a cross-linking agent in resin-finishing of cotton and of cellulose/polyester blends. They investigate the effectiveness of natrium at various temperatures on crease recovery and yellowing.

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Vukusiae et al.20 recommend the use of polycarboxylic acid with a mixed catalyst as an ecologically sound alternative, but find that it is too costly and discuss means of overcoming this defect. The ability to repel oily stains is provided by the application of compounds such as silicones or organofluorochemicals to the fibres. These materials function by preventing any permanent attachment between the hydrophobic molecules of the oil and the fibre molecules by interposing an oleophilic layer between the two. As usual, the substance is a toxic agent, so its effects are felt if disposal (* W-3) in waste water is attempted, and its manufacture also involves environmental risks. Scott21 provides details of a coating treatment that can make fibres resistant to water, oil, grease and solvent staining and which is durable in use. The coating has been applied successfully to cotton, synthetic and glass products, at the fibre, yarn or fabric stage, by gas plasma techniques. An anonymous writer22 also mentions a water-resistant coating that can be used as an alternative to polyvinyl chloride (PVC), based on a copolymer of polyolefin and ethylene vinyl acetate, that is claimed to be ecofriendly on the basis of using no chlorine or bromine. Vohrer23 notes that, as a result of societal demands for textiles produced by environmentally sound methods, plasma treatment (the application of an electrical discharge in a gaseous medium) is likely to become more common in the near future.

7.5.6 Flame resistance Flame resistance is a topic that has occupied the attention of textile scientists for several decades. It is an inevitable end result of exposure to an open fire that a material which, like many textiles, contains a large amount of carbon in its molecule, may well burst into flame. If it does, the person wearing the material is likely to suffer burns, while others in the vicinity may be overcome by the fumes emitted or may be trapped in a building because they are unable to see through the smoke evolved. The methods adopted by the industry as far as possible to counteract these risks are, unfortunately, somewhat suspect. The principle involved, as a result of legislation enacted in many countries, is one of preventing ignition or, more often, slowing down the rate of spread of any flame occurring. The first of these approaches, though apparently unimpeachable, is seen to be flawed on practical examination. The finishing agent used, usually a compound of phosphorus, nitrogen and/or a halogen, may (as is normally the case for most finishes of any kind) be removed by extended care procedures, such as washing or dry cleaning. Thus, after a period of use, an article thought to be resistant to ignition can in fact burn and a false sense of security may be engendered in the owner. Finishes designed to slow down the rate of spread of flame, in the same chemical categories, suffer from the same defect, but are also dangerous from another, more important, perspective. If, say, a cotton fabric ignites, it burns quickly and there is little time for intense heat to be produced in any one location. If it has been treated to slow down the rate of flame spread, the hot flame remains in contact with the

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fabric for a longer period of time, so heat buildup can occur in a small area. The resultant damage to an arm covered by the cotton will be more severe and can include third degree, rather than superficial, burns that will leave permanent scars at least and may well damage the arm so badly that a skin graft is necessary. If, alternatively, the flame spread rate reduction is achieved by blending with a (less rapidly consumed) synthetic fibre fabric, this fibre can melt and stick to the skin, causing even greater problems. Both categories of finish are inherently undesirable in the ecological sense. The reagents themselves are harmful when discharged into the waste water stream (* W-3), and may also cause skin reactions in some people. Disposal of the garments after prolonged use will allow leaching of any residual finish to take place, with further harm resulting once it reaches the underground water table. The end products of the combustion reaction if burning does take place are more dangerous for a treated fabric than for an untreated one, since there is an additional evolution of harmful chemicals such as hydrogen cyanide, halogen compounds or oxides of nitrogen, as well as a higher concentration of carbon monoxide as a result of incomplete combustion induced by the presence of the finish (* A-2). In addition, smoke density increases significantly in the presence of flame-retardant finishes, a factor that not only increases danger from a fire by preventing people from seeing an escape route (* A-3) but also adds to the pollution resulting from the combustion.

7.6

Colouration

One of the most troublesome current areas of concern in the textile industry is the pollution brought about by the colouration processes of dyeing and printing. Although they are not, strictly speaking, finishes in the generally accepted sense of the word, colouring agents are normally dealt with in this category. The main problem with the compounds used for applying colour is the fact that they are almost always, especially with reference to the original synthetic dyestuffs developed in the 19th or 20th centuries, highly toxic (* A-2), carcinogenic or (for good measure) both. Until fairly recently, they were released freely into the waste waters from the plant and could be seen boldly proclaiming their presence to all and sundry as a brightly coloured, but somewhat nasty, area of water. Of late, however, the industry has been trying valiantly both to reduce the effluent emerging from its dyehouses and to develop less harmful dyes but, although there has been some success in both of these aims, there are still large amounts of dangerous quantities of rejected dyes (* W-2, W-3) released from the washing treatment used to remove excess colour before continuing the fabric production train. Benisek24 provides a summary of ecofriendly dyes and packaging materials, while an anonymous author25 reviews a seminar devoted entirely to environmental issues, with particular reference to natural dyes, thickeners for printing paste and ecofriendly finishing.

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7.6.1 Dyeing with natural dyes The use of natural dyes, as opposed to synthetic ones, is often touted as a means of reducing environmental damage. Bhattacharyya and Acharekar,26 for instance, feel that the dyeing of jute with natural dyes to eco-specifications is now commercially feasible. There are, according to one author,27 benefits in lowered energy use, water consumption and allergenic effects, accompanied by easier biodegradation, though the problems of availability and colourfastness are noted. More serious concerns are voiced by Achwal,28 who points out that colour variation in natural dyeing can be so great that redyeing is needed, thus increasing the use of energy and water, with a consequent increase in both financial and ecological cost. Other writers29 add the observation that the necessary amount of dyes required would denude nature to an unacceptable extent, thus offsetting any possible advantages.

7.6.2 Synthetic dyes For all these reasons, recent work has tended to seek new means of adopting synthetic dyeing techniques with lower planetary loading, a matter of increasing importance according to one writer,30 who notes that the initial cost is high enough to discourage many manufacturers. However, the long-term savings in water, dyestuff, energy and waste treatment costs are appreciable. A crucial change in dye chemistry is being sought by several authors, mainly as a result of the harmful effects of certain dyestuffs, while a second approach suggested31,32 is the use of plasma treatments (low-temperature electrical gas discharges, such as those that can be achieved with a corona glow) to accelerate dyeing, increase brightness or improve penetration and hence fastness. Figure 7.4, taken from the former paper, shows the effects of plasma treatment on the dyeing rate (for various natural dyes) associated with the use of oxygen, ammonia and carbon tetrafluoride sources. It can be seen that there is virtually no change between treatments as a result. Similar plasma treatments have been used to increase fibre quality in wool combing (with less waste water),33 or to modify wool surfaces in other applications,34 and thus are worth examining as a technique for improving dyeing. Detailed information on all of these areas can be found in papers summarised in Section 5 of the Appendix.

7.7

Pollution aspects

The discharge of pollution from colouration processes occurs in two critical ways. First, when the dye is applied to the fabric (or to some other fibre assembly if dyeing is carried out at an earlier stage of the production), the colouring agent is not all picked up by the fibres. There are inevitably some residual amounts of dyestuff that cannot be adsorbed and, although efforts are currently made to recycle them (as detailed in Chapter 13 and the Appendix), there are large quantities that cannot

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7.4 Effects of different types of plasma treatment on dyeing time of wool with various natural dyes;
, untreated; ∆, oxygen plasma;
°, ammonia plasma; , carbon tetrafluoride plasma (source: ref. 31).

be reused, either because the particular shade is no longer applicable for the next fabric batch, or because the dilution is too great to make recovery economically viable. It is possible to distinguish to some extent between the different types of dye used, in order to allow some estimate of the relative harmful effects of each one to be made and a comparison of the chemistry of various dye types is of value in this exercise.

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7.7.1 Acid and cationic dyes The simplest dye types are probably the acid and cationic (or basic) ones. These are applied directly to the fabric and are obtainable in a wide range of colours. However, they tend to have poor fastness, bringing about premature rejection of the dyed product (and hence early pollution) and many of them are carcinogenic or otherwise toxic (* W-3). More recently, substantive direct dyeing has been introduced with the aim of increasing fastness and hence reducing waste, a beneficial step from the ecological as well as financial point of view. Azoic dyes generally need low temperatures (for which energy is expended) and use toxic (* W-3) chemicals for their production. Mordant dyes, which depend on an auxiliary compound to provide fastness to light and washing, suffer from the fact that most mordants are heavy metals (notably chromium) that can bring about serious environmental problems once the excess reagent is discarded. Recognising this drawback, Parton35 suggests that alternative dye types should be sought and recommends reactive dyes with an increased range of colours without the chromium effluent. These combine chemically with the fibre, tending to be exhausted reasonably effectively. Disperse dyes, used in colouration of synthetic fibres, tend not to be as wasteful as are some other types, because the dye is insoluble in water but soluble in the fibres, so is less of a problem to extract once the process is complete. Sulphur dyes, also insoluble in water, can similarly be removed from waste liquors slightly more easily than most other types. Thus, both of these provide a means of reducing pollution. Vat dyes are applied as a colourless precursor and need the presence of oxygen to develop their colour; they may therefore be more difficult to control (since the precise depth of shade cannot be seen until dyeing is complete), with the resulting possibility of increased chances of rejection of the dyed goods. Finally, solution dyeing, in which the colour is developed by solubility of the dyestuff directly inside a synthetic fibre, is possibly even more easily prevented from polluting the water supply.

7.7.2 Relative hazards In all cases it must be remembered that the actual chemicals from which the dyes are made may be harmful in varying amounts, so that the escape of a small quantity of an efficiently applied dye type may be more dangerous than the leakage of a larger quantity of one that cannot be controlled as well. The human factor, too, should not be ignored. If the technologist carrying out the dyeing operation makes a miscalculation or fails to follow instructions properly, even the most efficient dyeing process can lead to disastrous production of large quantities of dangerous waste material. Shukla36 derives a list of the chemicals used in textile auxiliary treatment in 1997, noting that there is a shift towards environmental concerns in the selection of chemical agents used. His list incorporates not only dyeing and printing auxiliaries, but also those used in softening, flame resistance, oil repellency,

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antifoaming agents and fibre-protective substances of various types. Efforts to reduce the emission of harmful agents are in evidence, as found in material also included in summarised form in Section 5 of the Appendix.

7.7.3 Supercritical dyeing Other approaches are being sought. Lennox-Kerr37 discusses new developments in dyeing with supercritical fluids, especially in attempts to reduce the current high cost that makes the process not economically viable. The theory behind this approach is that, if a substance that is normally a gas at room temperature is subjected to extremely high pressure, it can be liquefied. In this state, if it happens to be a suitable solvent, it can dissolve the chemical in question (a dyestuff in this case) and, when pressure is released, the liquid will evaporate, leaving the dissolved substance behind in the position to which it has been carried (i.e. the interior of a fibre in this example) while in solution. Lennox-Kerr notes that, in place of the most commonly used supercritical fluid, carbon dioxide, others like alkanes, ammonia, carbon monoxide and nitrous oxide, should be or are being tried and gives a summary of the process. Kawahara et al.38 examine the behaviour of a new type of polyester, made by a high-speed spinning technique, during supercritical dyeing with carbon dioxide. In comparison with conventionally produced fibres, the new polyester (which has comparatively large crystallites and low birefringence) is superior to the conventional one in dye uptake at low temperatures, but not very different at higher ones. The reason deduced for this behaviour is that fibre swelling in the supercritical fluid needs to reach a certain level, after which the dye diffusion is promoted and the larger crystallites mean that the new fibre reaches that level at a lower temperature.

7.7.4 Plasma treatments Özdogan et al.39 use plasma polymerisation to increase the dyeability of cotton in low temperature media. The treatment introduces to the anionic surface a cationic phase, and the resulting enhanced dyeability reduces water consumption, pollution and amount of dye needed. The authors suggest that there may be a benefit from developing modified dyestuffs to take advantage of the new technique when commercial applications are in progress.

7.8

Printing

In turning to printing, we should note first that virtually all printing processes use the same reagents as do dyeing treatments. Thus, the identical potential for harm exists in printing and the same relative risks for each type of dye used are also present. There are, though, added problems involved in printing and, in partial compensation, some minor benefits too.

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7.8.1 Principles Printing involves the localised application of dyestuffs to selected areas of a fabric. In order to prevent the dyes from straying outside the desired area, some means of lessening the ability to move must be incorporated. The aid used is a printing paste, a thick substance such as starch, gum or resin that increases greatly the viscosity of the colouring agent applied. This thickener is, of its own accord, a pollutant and can cause water pollution (* W-3) when excess amounts are discarded after the printing process is complete and the equipment is washed in readiness for the next batch, of a different colour. There is an awareness of the problem; Galgali40 proposes, for example, that ecofriendly pigments (ones causing no evolution of carcinogenic formaldehyde) should be adopted, a step that appears slow to be accepted. Zacharia41 collects kerosene from printing by using a cool chimney effluent and separates the substance from water in order to lower pollution. In compensation for the increased pollution risks, though, is the fact that a printing paste can often be more easily collected, with lesser amounts lost, than can a dye liquor. In addition, because the whole purpose of a printing step is to force colours into fibres, there is often less need to wash out the excess colour, so leading to lower quantities of discarded pollutants.

7.8.2 Direct methods As in dyeing, there are several variants of printing methods, including block, roller, screen, resist, discharge, flock and transfer. In the first three of these, classed together as direct methods, the colouring agent is merely applied to the fabric surface and pressure (derived from a wooden block, a metal roller or a rubber squeegee, respectively) is used to force the dye paste into the body of the fabric for absorption by the fibres.

7.8.3 Resist printing In resist printing, a protective coating is first applied to the surface to prevent contact or attachment between the dye and the fabric in that region. The resist paste is applied in exactly the same manner as a printing paste, using chemical agents that block either the physical access of print paste to the fabric or the ability to form a chemical bond between fabric and colouring agent. Substances used (in addition to thickeners, which are needed to restrict movement away from the area that is to be prevented from becoming coloured, in the same way as direct methods) include paraffin and various resins. Each of these, but especially the latter, can be responsible for environmental risks (* W-3) after the excess is discarded. Once the resist paste is in place, the fabric is piece-dyed. The problems involved in the step exactly match those used in piece-dyeing itself.

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7.8.4 Discharge printing In discharge printing, the order of operation is essentially reversed. The fabric is piece-dyed initially, then a discharge agent (one that destroys the colour of the dyestuff) is applied to selected areas to create a pattern of a white zone on a coloured one. The latter two methods are both used as a means of obtaining a richer colour in the dyed areas, since piece-dyeing gives a much greater intensity of shade than does printing. From the environmental perspective, the processes combine the worst aspects of printing and dyeing, because the disadvantages of using paste are supplemented by those of piece-dyeing, and the need to add extra reagents in the form of the resist or discharge agents compounds the problem still further.

7.8.5 Flock printing Flock printing consists of the application of short dyed fibres to the surface of a fabric, either over the entire surface or in specific areas, with permanent attachment to the fabric being achieved by the use of a resin or other type of glue. Again, the ecological aspects of dyeing (of the fibres) have to be considered, in addition to those of the fixing agent when excess amounts are discarded to the environment (* W-3).

7.8.6 Heat-transfer printing Heat-transfer printing is an attempt to decrease pollution problems. It is most easily applied to polyester fabrics, using a dye-impregnated sheet of paper as an intermediate medium to contain the dye in readiness for application. The paper and fabric are placed in close contact, heat is applied to cause sublimation of the solid dye to a vapour phase, which is transferred across to the fabric as a result of the temperature gradient. The dyes (of acid or cationic class where dyeing of natural fibres is attempted and disperse dyes which are used to best advantage for synthetic fibres) provide a wide range of deep colours (thus preventing to some extent early discard of fabrics that have faded) and are able to attach themselves readily to the fibre molecules, with moderate to good permanence. The effect is to remove completely all need for liquids and printing pastes, omitting the washing, steaming or drying steps in conventional drying, so reducing the ecological harm. However, the need to make special paper and for a separate printing stage when applying dye to it, together with the disposal of the paper (* V-2), reduce considerably these advantages.

7.9

Drying and shipping

One further process needs to be considered, fabric drying. Again, it is not strictly a finishing treatment, but virtually all of the fabrics undergoing a finishing stage

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need to be dried at least once, and often more times, at some point in manufacture. The process is considered in Chapter 11, but is mentioned here because it is so important in finishing. The fabric has to be packed for shipment. This step, which is essential for protection from the elements, needs some form of outer coating, such as kraft paper or plastic, that has to be manufactured, with the usual environmental cost. In modern factories, it also involves the use of machinery, incorporating its costs. Finally, the matter of transportation should be considered. As before, this may be necessary during all parts of the production train, but the shipping of finished cloth is probably the largest single use of the operation. These then, are the harmful effects on the planet associated with the manufacture of textile fabrics. Unfortunately, the problem does not end here. After the finished articles are passed on to the consumer, there are still more costs incurred as a consequence of their use. These will be the subject of the next chapter.

References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Arang, T. and Fernandez, J., Revista Quim. Textil, 1998, 139, 47–55. Korner, C., Melliand Textilber., 1999, 80(1–2), 73–76 and E 21–24. Xu, W., Cui, W., Li, W. and Guo, W., J. Soc. Dyers Colourists, 2001, 6, 352–355. Cheng, H., Yejuan, J. and Kai, S., J. Soc. Dyers Colourists, 2000, 7/8, 204–207. Geubtner, M. and Hannemann, K., Melliand Textilber., 2001, 7(September), 245–248. Lal, R.A., Colourage, 1998, 45(annual), 61–70. Soljacic, I., Katoric, D., Marija Granaric, A. et al., Int. J. Clothing Sci.Tech., 1998, 10(6), 98–101. Gulrajani, M.L., Asian Textile J., 1999, 8(2), 28–30. Mathew, M.R., Man-Made Textiles in India, 1999, 42(3), 97–101. Duschek, G., Melliand Textilber., 2001, 7(September), 240–244. Barton , J., Int. Dyer, 2001, 6, 11–12. Fung, W., Coated and Laminated Textiles, Cambridge, Woodhead, 2002. Bajaj, P., ‘Thermally sensitive materials’, in Tao, X. (ed), Smart Fibres, Fabrics and Clothing, Cambridge,Woodhead, 2001, p. 70. Kubin, I., Melliand Int., 2001, June, 134–138. Zyschka, R., Melliand Textilber., 2001, 7(September), 249. Min, R.R. and Huang, K.S., J. Soc. Dyer. Colourists, 1999, 155(2), 69–72. Rathi, D., Man-Made Textiles in India, 1999, 42(6), 231–234. Ramaswamy, G.N., Wang, J. and Socharto, B., Textile Chem. Colorist, 1999, 31(3), 27– 31. Saraf, N.M. and Alat, D.V., Colourage, 1998, 45(9), 27–34. Vukusiae, S.B., Katoviae, D. and Soljaeiae, I., 79th World Conference of Textile Institute, 10–13 Feb 1999, Chennai, India, Vol 2, pp. 51–59. Scott, I., World Sports Activewear, 1998, 4(4), 24–25. Anon., Textiles Mag., 1998, 27(4), 4. Vohrer, U., Asian Textile J., 1998, 7/8, 93–96. Benisek, L., Textile Horizons, 1999, 19(1), 24–25. Anon., Colourage, 1998, 45(12), 47–49.

Fabric treatment processes 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

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Bhattacharyya, N. and Acharekar, S., Br. Textile Res. Assoc. Scan, 1998, 29(2), 18–25. Anon., Knitting Tech., 1998, 20/4, 170–171. Achwal, W.B., Colourage, 1998, 45(1), 45–46. Doraisamy, I. and Janakiraman, K.P., 79th World Conference of Textile Institute, 10–13 Feb 1999, Chennai, India, Vol 2, pp. 29–32. Anon., Int. Dyer, 1999, 184(5), 28–30. Wakida, T., Cho, S., Choi, S. et al., Textile Res. J., 1998, 68, 848–853. Anon., Textile Dyer and Printer, 1998, 31(21), 17. Ganssauge, D. and Thomas, H., DWI Rep., 1999, 122, 451–455. Morse, V., Thomas, H. and Hocker, H., DWI Rep., 1999, 122, 514–519. Parton, K., Int. Dyer, 1999, 184(4), 14–17. Shukla, S.R., Colourage, 1998, 45(annual), 175–186. Lennox-Kerr, P., Int. Dyer, 2000, 5, 29. Kawahara, Y., Kikutani, T., Sugiura, K. and Ogawa, S., J. Soc. Dyers Colourists, 2001, 5, 266–269. Özdogan, E., Saber, R., Ayhan, H. and Seventikin, N., J. Soc. Dyers Colourists, 2002, 3, 100–103. Galgali, M.R., Colourage, 1998, 45(7), 20–22. Zacharia J., Br. Textile Res. Assoc. Scan, 1998, 29(3), 1–2.

8 Use of textiles

8.1

Primary and secondary production

Once a textile fabric has been manufactured, its potential for causing damage to the environment does not end. A fabric, no matter how high its quality or how well it is finished, coloured and generally enhanced, is of little or no use unless it is made into something. The possible products of this further processing include such widespread objects as clothing, upholstery, drapery, bedding and industrial goods. We normally tend to regard the primary (i.e. fabric production) and secondary (i.e. products made from fabrics) textile industries as separate ones, but the environment makes no such distinction; pollution is pollution no matter what its source may be. One of the major problems facing the entire industry today is a lack of communication between these two different areas, since there is often a misinterpretation of the needs of the secondary sector by members of the first one, as well as a misunderstanding of the capabilities of the primary industry by the secondary one. Nature may benefit substantially by the development of a closer connection between the two, reducing the number of discarded materials that result from these failures to match needs, abilities and production.

8.2

Types of use

In view of the nature of this book, a distinction is proposed here between different types of use in a way not normally adopted. Those uses intended to protect the environment in some way will be separated from the others and treated in Chapter 13. This is obviously not a simple matter, because there will be immense grey areas where the two cannot readily be distinguished. A geotextile barrier designed to prevent flooding of houses in an area inundated with water from a burst river bank, for instance, is clearly intended to keep the human inhabitants of the threatened region safe and alive. A geotextile used to contain polluted substances in a landfill site from leaching out into the water table is intended to protect the environment. Yet, the flood barrier also prevents erosion of land by water flow, while the 90

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contained pollution is also prevented from poisoning human beings, so that both end results are met in each case. The distinction here (which is totally arbitrary and personal) is to determine what seems to be the more important criterion for use and to allocate the application to the section that makes most sense in that case. In this chapter, the ‘normal’ uses will be dealt with and the ‘environmental protection’ uses will be deferred to Chapter 9.

8.3

Normal uses

8.3.1 Clothing The most obvious normal use of textiles is in making clothing, a use that has been around for thousands of years. For the purpose of this chapter, products of the garment sector will include only clothing and accessories. As always, the machines needed to make them are complex, though usually much smaller in scale than those used in textile yarn and fabric manufacture. Cutting, sewing, pressing and other machines all need to be made and operated, at the now-familiar cost to the planet. There are frequently excess pieces of fabric that are cut away in making clothing to be discarded. It is, admittedly, possible to recycle these scraps, as will be discussed in the next chapter, but large, complex machinery is needed to put them back into the production train. Although such scraps may be too small anyway to make recycling worthwhile, one author1 describes yarns made with fibres recovered from the garment industry, noting that they avoid excess pollution by eliminating the need for fertilisers and dyes. Uses as socks, blankets and upholstery materials are mentioned specifically, a point that gives the key to this over-optimistic attitude. These articles differ from most textile end uses in that colour is not critical, unlike virtually all other applications. In more usual recycled goods, especially as they are almost invariably coloured, some process for removing all the dyestuffs is always needed. This involves chemical reactions in which bleaching agents or dye strippers are used to destroy the dye molecules or change their molecular structure to render them colourless. These substances are waste products that can harm the Earth once discarded into the environment (* L-2, W-3) (see Table 1.1 for an explanation of codes).

8.3.2 The fashion industry One of the most powerful driving forces influencing the manufacture of clothing is the fashion industry, which has increased considerably in importance in the centuries since the Industrial Revolution. Clothing is one of the easiest ways to display wealth conspicuously, so it is now accepted among people in many parts of the world (and particularly in the developed nations) that new outfits should be purchased at every season of the year. Seasonal variations in climate are an added major incentive for these expenditures and, in practice, the resulting annual

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production of clothing may be regarded as too great to be justified as environmentally responsible. Few people actually wear more than one outfit at a time, which means that many garments are stored in environmentally destructive plastic bags for a great proportion of their useful life. After the season ends, it is currently fashionable, in a kind of lip service to planetary well-being, to ‘recycle’ the articles via alternative outlets, such as second-hand clothing stores or factory shops selling designer clothes at reduced prices. Even this gesture is not entirely altruistic in terms of the Earth’s welfare; the loss of an article of clothing invariably leaves a gap that must be filled by something new in the wardrobe of the person making this supreme sacrifice. The premises where the unwanted garments are resold also need to be built, heated, lit, staffed and so on. Unfortunately, the pressures of the fashion industry appear to be increasing rather than declining, as would be preferable for ecological welfare. The problem, as always, lies in commercial interest. Modern people, especially in the developed world, are accustomed to the need to follow a fashion cycle on an annual or even seasonal basis, so that the fashion industry (and those connected with it) has a vested interest in ensuring a regular turnover of garments. It is inevitable that a large reduction in sales would lead to a major loss in employment, because it is not only the textile and clothing manufacturers who would be out of work, but also the designers, alteration staff, marketing specialists, transportation personnel, retailers, magazine editors or artists, and anyone else with an ancillary interest in the fashion world. The cumulative psychological effect on Society of the need of all these people to be kept in employment is difficult to resist, meaning that the relentless drive to be up-to-date will continue for as long as we (or our planetary home) are prepared to tolerate it.

8.4

Environmental aspects

8.4.1 Laundering The renewal of the fashion requirement per se does not merely cause environmental problems in the debate regarding recycling versus disposal. As a consequence of our modern lifestyle and technology, dust and dirt are omnipresent, and soiling necessitates emergency procedures in the form of laundering or dry cleaning. Both of these can cause environmental difficulties. Laundering involves exposing the textile article to the combined effects of water, heat, agitation and detergent. Often, an optical bleach or a fabric softener is added to the mix, and machine drying is frequently used. Both of these procedures give a much more luxurious feel than do an untreated wash and outdoor drying on a clothing line. The energy needed to heat the water and operate the machinery, together with the chemicals (* W-3) discarded into the drain, are a source of harm, as also are the heat needed to operate and the polluted exhaust emitted (* A-2) from the dryer. The thermal load from both washing and drying can also affect the surrounding air or water (* W-1), making

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it unsafe for other species to exist in the neighbourhood of the discard point unless precautions are taken to reduce the rise in temperature occurring on discharge.

8.4.2 Dry cleaning Dry cleaning also has ecological consequences. The machinery needs to be built and operated, while the solvents used for extracting the dirt are often toxic or carcinogenic. Even though strenuous efforts are made to contain them and recycle them for later use, there is still an inevitable loss (* A-2) because of entrapment in the fibres or escape into the air via the garment transport path. Jipp2 describes nontoxic stain removal using solvents without chlorocarbons, so that the chemicals can be regarded as being kind to both fibre and environment. Nevertheless, all of the reagents used in maintenance, even these more harmless ones, have to be manufactured, with expensive loading on the environment.

8.4.3 Maintenance chemicals The actual chemical substances used in maintenance can be examined in more detail to ascertain their potential for harm. As a consequence of our current fascination for cleanliness, garments are washed or cleaned far more often than is necessary for the sake of health or even hygiene. For this reason, the quantities of detergent, softeners, bleaching agents, dry cleaning solvents or other chemicals expelled are enormous. Detergents contain alkalis and organic chemicals that act as pollutants (* W-3). They also often contain phosphates, used as ‘builders’ to enhance the effectiveness of the washing action, which are known to encourage the growth of algae in large bodies of water. These can take over the oxygen available in the water, preventing other species (both animal and vegetable) from having access to it, As a result, fish can die and the balance of the local aquatic plants can be disturbed seriously, bringing about major changes in the locality and eventually resulting in a dead body of water where fish no longer exist and weeds choke the entire surface. Fabric softeners, usually quaternary ammonium compounds, are becoming more and more popular. These bring about water pollution (* W-3). They are produced by relatively complex chemical reactions, with the usual environmental concerns and their disposal brings about harmful changes in the local water supply.

8.5

Household textiles

In the home, textiles find widespread use, from household furnishings such as carpets, cushions and table linens, to towels, bath mats or dish cloths. David Rigby Associates3 give an overview of the various types of textile applications in home furnishing products, suggesting that the largest growth in the foreseeable future will occur in non-wovens or fibrefill categories, rather than in the more traditional

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woven or knitted fabrics. Two unusual applications in the household category have been reported in the literature; one author4 writes of the usefulness of wool tightly woven and attached to gypsum board (in the form of decorative panels) as a means of combating the relatively new hazard of sick building syndrome by absorbing the formaldehyde reputedly responsible for this problem. The second application5 consists of a system used to wrap houses during construction to maintain acceptable working comfort, for craftsmen operating on the outside walls of the house in adverse weather conditions, with enough moisture vapour permeability to ensure that breathing comfort can be retained.

8.6

Industrial and medical uses

8.6.1 Technical textiles Bhonde6 gives an overview of textiles used in applications beyond those of clothing or household purposes, while Legler7 examines technical textiles from the perspective of recent advances. Both authors more or less agree on the list of end uses, including geotextiles, agrotextiles, industrial products (including composite reinforcement), automotive, space, protective and medical ones. Not mentioned specifically in this list is the use of textiles in building, which may be extended to the subject of architectural fabrics. Their adoption, according to Hill,8 reduces building time significantly and saves natural resources (a valuable advantage from our point of view!), while providing long life and cost-effective, aesthetically pleasing appearance. Swedberg9 describes applications of tent structures using PTFE-coated fibreglass with steel tubing and cables and, in a later paper,10 the use of air-inflated beams for supporting massive structures in high wind or loading conditions with potential applications in aerospace or nautical projects. Other interesting applications are the use of a composite of high-tensile glass with epoxy resin to make a reinforcement beam as protection against earthquake collapse11 and wrapping corroded bridge columns with carbon fibre12 to prevent further damage.

8.6.2 House construction House construction can also be aided indirectly by fibres, when used as reinforcement for concrete or in other aspects of building. In such applications, the environment is preserved by preventing premature failure of the material, allowing it to last longer. Peter13 recommends Kevlar for concrete reinforcement, because it imparts low density, non-catastrophic failure (and resistance to repeated impacts) to the concrete. In addition, because the fibres are electrically insulating, Kevlar permits building to take place more safely near high-voltage power lines. Komatsu et al.14 assess the durability of geotextiles in reinforcing asphalt concrete, noting that this process increases viscosity of the material and reduces the stress

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concentration of wheel loading. Locatelli15 reports the production of a stretchable roofing felt that can be installed and maintained without shrinkage when used in a layered system. A French company16 is marketing a woven structure that can be laid across soft, sandy or swampy ground, allowing vehicles to pass safely. In temporary houses, such as tents, fabrics are invariably used for their combination of light weight, easy folding ability, weather (especially wind) resistance and versatility.

8.6.3 Motor vehicles Fung17 provides a detailed description of the many applications of textiles, in the form of coated or laminated fabrics, in vehicles. He includes in his listing seat materials, headliner structures, other interior coverings, air bag components, convertible coverings, liners for bonnets or wheel arches, carpeting, noise control items and drive belts. In view of current traffic hazard concerns involving motor vehicles, the air bags used to enhance safety in crashes have received particular attention. One writer18 recommends the use of nylon 4.6 in making them, because of its better thermal stability. Barnes and Rawson,19 after devising a new test to assess the efficiency of coated fabrics for this end-use, find that nylon 6.6 is better than either nylon 6 or polyester in this regard. They also report that a silicone-based coating should be applied to the fabric to increase thermal resistance still further. Gutlein et al.20 recommend a polyurethane bladder in a textile net for making sideimpact bags, while yet another author21 would like to see needle-punched construction methods used to increase permeability in a controlled manner and describes conditions for achieving optimum gas transfer characteristics.

8.6.4 Medical textiles Medical uses of textiles should also not be ignored, as they constitute a major area of advance for the industry. They are summarised in Section 6 of the Appendix, where more information regarding applications (such as in surgical uses of clothing and inserts into the body, or general medical clothing and health care) can be found.

8.6.5 Industrial applications The widespread use of textiles in industrial applications, however, is not generally discussed in any detail. Various authors17, 22 write articles dealing with the many valuable attributes of technical fabrics, including those intended for space activity, automotive filtration, airbags, composites, marine uses, laminating, seismic protection and resistance to harmful agents. Applications range widely in type and some consideration of representatives of all the varieties of application should be

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included. They may be divided into those used directly by industry, those used in leisure or sport activities and those in which heavy duty use is needed in everyday life. Textiles used directly in industry include such diverse items as tarpaulins, filters, acoustic or thermal insulation and protective garments for workers.

8.6.6 Other uses Three specific types of more interesting use can be identified. First, transport via heavy lorries is rendered less perilous (and has a lower risk of polluting the road or causing accidents by losing part of the material being shipped) by the use of a new kind of tarpaulin,23 knitted from stretchable textured polyester, that conforms to the shape of a load, reducing flapping as the vehicle moves. Second, filters appear to be popular subjects for research, an occurrence caused at least in part by the need for a cleaner environment. Third, leisure or sport applications are rapidly increasing and include items such as tentage, sleeping bags, boat sails, mooring ropes or other marine cordage, aircraft skins, parachute fabrics, climbing ropes, bungee cords, balloon fabrics or guy ropes. Little attention appears to have been paid to most of these applications, although there are some papers worth mentioning in the literature. The work taking place in each of these areas is summarised in Sections 7 and 8 of the Appendix. Finally, one or two less obvious uses may be mentioned. Newberry24 reviews new developments in the use of composites in corrosion-resistant applications such as piping, lamp poles, and tanks to contain hot brine or for use in deionised brine service. Risks of harm from mobile phones, reportedly causing brain damage from electromagnetic radiation, are supposedly counteracted25 by the use of a flexible metal-coated fibre, preferably an acrylic one coated with copper or nickel. Plates used to press boards of plywood, or those for printed circuits, lined with textile cushions designed for high-temperature use, are reported,26 while Marsh27 discusses the use of fibre-reinforced plastics for improving under-sea oil extraction; the smooth surface, chemically inert nature and low weight mean that lower losses from corrosion and oil escape will occur, so providing an ecological benefit. Kotliar28 uses textile and carpet waste to produce a low-cost, wood-like material by incorporating them in a high-modulus phenol/formaldehyde matrix. Other heavy-duty uses in everyday life include tyre cords, seat belt webbing, vehicle upholstery, carpeting, wall hangings, conveyor belts, drive belts, tow ropes, isolation suits, protective clothing, space suits, architectural fabrics and geotextiles. In addition, cleaning cloths, surgical clothing or drapes, bandages or other dressings should also be added to the list. Many of these will be dealt with later in the book but, as a final general comment here, we should note that all of them, in common with all the cases mentioned above, have a production process that tends to be an expensive one from the environmental perspective and, in many cases, create difficulties in disposal.

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References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Anon., Amer.Textile Int., 1998, 27(8), 84. Jipp, M., Bekleidung Wear, 1998, 50(20), 48–49. David Rigby Associates, Textile Horizons, 1999, 19(1), 12–15. Anon., Wool Record, 1999, 158/3657, 20. Bay Mills Ltd., High Perf. Textiles, 1999, August, 6–7. Bhonde, H.U., Synthetic Fibres, 1999, 29(1), 17–19. Legler, F., Textile Horizons, 1998, 18(5), 10–13. Hill, D., Tech. Textiles Int. 1998, 7(6), 17–23. Swedberg, J., Ind. Fabric. Product Rev., 1998, 75(4), 16–18. Swedberg, J., Ind. Fabric. Product Rev., 1998, 75(4), 52–55. Hexcel-Fyfe Co., High Perf. Textiles, 1999, June, 6–7. Ma, G., Adv. Comp. Bull., 1998, December, 1–12. Peter, E., High. Perf. Textiles, 1999, August, 5. Komatsu, T.et al., Geot. Geom., 1998, 16(5), 257–271. Locatelli, A., High. Perf. Textiles, 1999, August, 6. Societé à Responsabilité Limitéé Deschamps, High. Perf. Textiles, 1999, July, 7–8. Fung, W., Coated and Laminated Textiles, Cambridge, Woodhead, 2002. Anon., High Perf. Textiles, 1998, December, 4–5. Barnes, J.A. and Rawson, N.J., Textiles Asia, 1998, 29(11), 37–40. Gutlein, U., Schaper, J. and Von Dreyse, J.S., Textiles Usages Techniques, 1998, 29, 62– 64. Anon., High Perf. Textiles, 1999, January, 6–7. Various authors, Textile Month, 2000, March, 6–22. Wagner, J.E., High. Perf. Textiles, 1999, August, 7–8. Newberry, A.L., Reinforced Plastics, 1998, 42(8), 34–38. Daiwabo Co. Ltd., High. Perf. Textiles, 1998, October, 4. Du Pont Taiwan Ltd., High. Perf. Textiles, 1998, September, 5–6. Marsh, G., Reinforced Plastics, 1998, 42(11), 32–36. Kotliar, A.M., Polymer Plastics Tech. Eng., 1999, 38(3), 513–531.

9 Environmental protection

Now that we have examined the way in which textile production and use can harm our planet, it is time to look at the steps we are taking as a society to minimise that harm. In this chapter, we will look at the ways in which governments attempt to compensate for the damage caused within their jurisdiction, how successful they are and how we can evaluate their success (or lack of success) in stopping environmental damage. We should not forget that other industries, besides the textile one, are guilty of causing the same pressures on planetary health, but this book must concentrate on how textile manufacturers and ourselves, as textile consumers, should be judged. In particular, what steps are being taken by the industry to minimise the onslaught that textile production makes on the health of the planet and how effective are these steps?

9.1

Commitment

The most critical point is a distinct lack of commitment on the part of many governments to do anything but pay lip service to the environmental lobby. There are plenty of examples to support this admittedly pessimistic viewpoint. The most recent one, at the time of writing, is the refusal of the USA to ratify the Kyoto Accord, on the grounds that it is likely to be ineffective. It seems to the author that any move towards restricting toxic emissions, even if ineffective, is better than agreeing to permit virtually unlimited pollution by industry to continue unabated, presumably because curbing the polluting activities would be economically harmful. The Earth Summit in Rio de Janeiro in 1992, too, is looking more and more like a waste of time as the years pass by without any tangible action on its recommendations. The ready availability of weapons of destruction to both sides in a war, as long as there is money to pay for them, also appears to reflect a somewhat cynical attitude to preserving our planet unharmed. So does the willingness to ship oil to every part of the globe without much long-term concern whether a tanker is wrecked and spews its polluting cargo over pristine beaches. Environmentalists are regarded as antisocial creatures determined on a course of action intended to wreck the economy, rather than as conscientious citizens trying to save their 98

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planet. The time has surely come for governments to be more responsible in investing for the future welfare of the Earth, rather than in trying to maintain high living standards for a favoured few citizens.

9.2

Protective applications

There are many published references in the area of environmental protection in the textile context, including some general ones dealing with the need for the industry to attack pollution problems. Germany establishes regulations1 to limit or eliminate environmental and health hazards for textile and leather processing industries. Japanese textile firms2 emphasise harmony with the environment, mentioning, for example, the possibility (well known for many years in the West) of recycling used clothing. They also introduce industrial consumers to the ideas of producing environmentally friendly products, saving energy and reducing water pollution. Orzada3 carries out a survey to discover the degree of development of environmental responsibility regarding products and processes in the USA apparel industry, looking at types of environmentally friendly products, environmental policies, fabric waste disposal and reduced packaging waste. Cunho et al.4 carry out research relevant to environmental aspects of textile materials, such as the impact of some environmental parameters on fibre properties and the evaluation of products on the basis of their environmental safety. Muirhead5 considers the development of environmental awareness, touching on emission controls, water charges, landfill tax and packaging regulations as opportunities to increase profits and reduce costs.

9.2.1 Ecologically beneficial practices Benisek6 reports on a conference in which ecologically beneficial practices are one of the major areas of focus and on a later one7 with a strong emphasis on the ‘green’ future of textiles, including replacement of harmful catalysts or other reagents and improved dyeing or finishing conditions. Smith8 discusses the greening of the textile supply chain, noting that cleaner products and better waste management are essential. Gale et al.9 produce a regular column dealing with environmental matters and include in this particular one reports or suggestions such as (a) water pollution should be limited by water quality, not individual discharges, (b) some new dyes and pigments may change in classification regarding toxicity and (c) benign chemicals (in a wet processing stage, with special procedures to prevent dimensional changes in fabrics) are being sought as an alternative to perchloroethylene in dry cleaning. In another general review article of environmental issues, Gale and Bide10 report a recommendation to limit the ammonia content in effluent (* W-3) (see Table 1.1 for an explanation of codes) with reference to early life stages of fish. They mention, too, concerns about tributylin as an antibacterial agent that, even though it is not supposed to be used because of its hazard to health, has

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nevertheless been found on certain football shirts that have now been withdrawn from the market; it is entirely possible that other examples of this kind of irresponsible manufacturing may exist. In the same article, the authors also summarise work dealing with dye decolourisation with oxides of zinc or titanium, or with hydrogen peroxide in conjunction with ultraviolet radiation, then discuss the aerobic treatment of dye waste water. The same two authors, in yet a further article,11 record the move towards replacing regulatory control of pollution with voluntary responsibility based on incentive, an apparently dangerous precedent in view of the tendency of many manufacturers to ignore environmental concerns totally until forced to take them into account. They also note revived interest in low-wet-pick up techniques in dyeing (such as the use of foams) to reduce the amount of water needing to be removed in drying, so decreasing costs. The recycling of water, they feel, is becoming more attractive as disposal costs rise and they mention water-saving techniques such as filtration and the use of membrane, biological or ozonation procedures, as well as a new method to allow recycling of solvents by low-pressure steam. Barton12 examines the rise of the ‘organics’ market, especially as it pertains to textiles. She discusses the establishment of units to influence development and marketing of the technology in an effort to achieve sustainable solutions. However, she notes that banned compounds can still be found in clothing, possibly lowering safety levels. As a kind of compensation, she then reports a new initiative to produce organic textiles for clothing and household uses at prices comparable to those of standard (i.e. non-organic) goods.

9.3

Legislation

It is true that some legislation to reduce planetary harm exists. Arias13 describes the criteria that a manufacturer must meet in order to use the European Union’s ecolabel. There are 34 separate standards to be considered, relevant for all types of fibres, processes, chemical products and suitability for end use. The objective of the programme is to reduce air and water pollution and increase both human health and public awareness of the problems existing, as well as lowering water and energy consumption. McCarthy and Burdett14 introduce details of an ecolabelling production chain, discussing the effluent issue. They describe product disposal and review label types, including in their article a consideration of the relevance of the labelling regulations to the textile industry and the benefits of environmental awareness. Achwal15 feels that the ecolabel guarantees environmentally friendly production. He discusses background use and criteria for its adoption and provides a list of banned azo and carcinogenic dyes, plus a list of permissible limits of other harmful chemicals, with each process hazard criterion identified. McKenzie16 warns of the dangers of assuming that natural fibres are less environmentally harmful than synthetic ones.To support her contention, she provides a comparative analysis of the ecologically relevant steps in the production of natural, regenerated and synthetic fibres. In a later paper,17 she observes that, although the demand for

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organic cotton has grown recently, consumers are not prepared to pay higher prices for the benefits of environmental conservation. She also notes18 that ecofashion costs more until mass production output is attained, but there can be no mass production until demand rises, which will only happen when cost decreases. Consumer education is needed, but she remains adamant in her conviction that natural fibres cannot automatically be assumed to be inherently ecologically friendly. Elsasser et al.,19 in a paper dedicated to clear processing in the recycling of textile waste, include many legal aspects of shredded fibre use. European Union directives on integrated pollution prevention and control are reviewed by Shaw,20 who also provides a prediction of the effects they might have on wet processes in wool production.

9.4

Future prospects

Future prospects in an age of environmental concern are also considered by Dixit,21 who feels that there may be a risk of some companies being closed because of an inability to meet the ecological challenge. He emphasises the need for safer and better treatments for reducing pollution to satisfy the newly emerging regulations. Shaver22 stresses the need for companies to enhance their management of environmental responsibilities because of the projected increase in costs and liabilities. He recommends an environmental management system as a cost-effective way to establish level of commitment, developing plans, programmes, or controls and correcting problems. By its adoption, he feels, the environmental effects of production will become obvious and a reduction in costs will be accompanied by a gain in recognition for the company.

9.5

Financial benefits

Financial benefits of ecological responsibility are also predicted by several other workers. Battersby23 suggests that the expenditures for environmental protection may be of great advantage to a company, because they can give major tax deductions, a nice surprise at the fiscal year end. More tangible benefits are reported by Moore et al.24 who find that environmentally driven action can actually improve production and that more than three-quarters of the companies they investigated made changes to their production techniques with environmental conservation in mind, often surpassing government regulations. Wakeling25 suggests that water recycling, currently regarded as a burden by manufacturers trying to meet environmental standards, can be an opportunity for saving money. He calculates that annual operating costs for water recycling are about £104 800 (after meeting capital costs of £300 000, but that savings amount to some £248 700, so that capital payback time is only 25 months, a period that should be regarded as better than merely acceptable. Hohn26 outlines ecological and environmental

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methods for waste water treatment, comparing and contrasting several techniques, and finds that the most ecologically beneficial one is also the most profitable. An anonymous author27 describes a new energy-saving stenter capable of reducing consumption by about 20% as a result of using a redesigned chamber and preheating incoming air with heat recovered from exhaust gases in a manner that also cuts emissions significantly.

9.6

Costs

There are, though, costs that cannot be ignored. Russell28 discusses the proposed EU tax on energy consumed, noting that textile producers will be heavily penalised in comparison with those from other industries because the processes are energy intensive, so the industry is likely to suffer high increases of up to 15% in fuel costs. Phillips29 brings to light a little-known source of both environmental and financial cost in the form of steam traps. Failure of one of these can involve a loss of about US $2000 and, with 100 to 200 in use in a typical textile plant, with a failure rate that often reaches 20%, total annual cost can approach $80 000. He advises manufacturers to select steam traps carefully, paying special attention to their suitability for the purpose intended, the condensate loads that each one is expected to sustain, any relevant safety factors and the differential pressure under which they will operate in comparison with their maximum allowable pressure.

9.7

Drawbacks

Despite all the regulations and the interest in them, however, it is my belief that they can never be satisfactory in providing environmental protection, simply because they are neither effective nor severe enough. It is true that there are many laws, differing in each jurisdiction, about what can and cannot be done in releasing compounds, or engaging in activities with ecologically undesirable effects, to the environment. These, for instance, usually set quantitative limits for each harmful substance or activity, regarding how much can be tolerated in a specific time period. They include laws about such matters as emission of air or water pollutants, and display of advertisements, signs or other types of visual pollution, as well as specifying the intensity of a sound level that may be released. A particular example of the noise pollution laws is the legislation that limits exposure of workers to ambient noise levels, summarised in Table 5.1 of Chapter 5. All of these laws are excellent in their intention but there are, unfortunately, five drawbacks that make them considerably less than ideally effective in practice. These are the nonuniformity of standards, the lack of enforcement of standards, the relatively insignificant penalties for flouting the law, disagreement on what is considered to be pollution and the lack of quantitative measures applicable to pollution violation assessments.

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9.7.1 Variation in standards The first of these arises from the fact, noted above, that different standards are adopted in different areas. It is not too long ago, for instance, that North American textile producers were shipping goods to Mexico or south-east Asia, where laws were much more lax, to have finishing carried out there that would have been illegal in their own countries. The finished goods were then returned to the original manufacturer to be sold as ‘domestically-produced’. It is true that some authorities are trying to improve the situation; the example given above is no longer applicable, mainly because the changes in laws in the former ‘dumping’ countries make it economically not worthwhile to pay the transportation costs involved, even though the standards there are still lower than in the host countries. Legislators are slowly responding to pressure from constituents to enact laws that enhance ecological responsibility, but changes tend to be of the ‘too little, too late’ variety. The attitude of many otherwise responsible scientists, who discuss endlessly whether the Earth is actually suffering from the presence of human activities, or whether the disturbances we observe are merely the result of natural climate cycles, is not helpful. What is clear (but often ignored) is that, even if the cyclic explanation is the true one, our behaviour will add to, rather than reduce, the ecological burden placed on the planet. The example of air pollution is probably the best known and several workers are active in carrying out research to improve the situation in an effort to meet more and more stringent laws. Baker et al.30 summarise air quality research in relation to cotton production, with special reference to ginning, discussing the removal of trash and potential means of improving the situation by the use of preseparators, modifications and improvements to equipment or procedures before emission to the atmosphere in the cyclone method. Rey31 provides guidelines on the technology available for controlling smoke and odours from textile finishing. Holme32 recommends a three-faceted method (considering emissions, efficiency and economy) for pollution reduction or prevention. In it, he looks at processes, identifies potential for improvement and assesses the effects (in comparison with other techniques), finding that cost reduction, lower emission and higher efficiency can result. The main objection to these lines of approach is that they are applied unevenly in specific regions. Smoke stacks still pour out noxious fumes, but the traditional solution that is still tolerated has always been to build the stack higher to allow the toxic effluent gases to be discarded further into the atmosphere and thus become dissipated. Legislation tends to accept this compromise, yet it is not an effective means of lowering pollution, as is becoming more and more obvious, as the number of stacks and the amount of gas discharged from them increase steadily. Air pollution is not localised; harmful gases are carried by wind or air currents to other regions and, eventually, to all parts of the world. Thus, a toxic reagent released into the air in one country can eventually bring harm to people in other

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locations. The most familiar instance of this kind is perhaps the Chernobyl disaster, in which a nuclear power station released harmful radiation into the air in the Ukraine; animals as far west as Great Britain were subsequently deemed unfit for consumption because they had ingested radioactive airborne particles. There are many other, less famous, examples of this kind of global dissipation of environmentally dangerous substances. Dioxins and furans, arguably the most toxic types of chemical known because they can bring about poisoning or adverse genetic mutations in extremely small concentrations, can be emitted (* W-3) from textile finishing treatments. Their discharge is, in theory, strictly forbidden in most developed countries, yet there are frequent reports in these very countries of their appearance in waste streams; it is cheaper to discard them, as long as the source of this crime is not detected, than to deal with them effectively and responsibly, simply because their destruction is, technically speaking, relatively difficult and hence costly. Sedlak et al.33 find that they arise mainly after treatment has been carried out, forming in chimney depositions. Carroll et al,34 on the other hand, estimate that textile treatments involving chlorinated organic compounds (the most important source of these toxins) only account for about 1% of the total dioxin and furan emissions in the USA. The industry, then, is by no means the only or even major culprit in this dangerous activity. Notwithstanding this assurance, the emission of any compound as harmful as these is undesirable and the lesson to be learnt from such comments is a simple one. Because emissions may not be different in different regions of the earth, standards of safety or of environmental protection need to be harmonised over the entire planet if they are to be effective. If there is a difference, then unscrupulous manufacturers will merely move their ‘dirty’ production activities to a part of the world where standards are less severe, if they can take advantage of the lax laws there by so doing, and will thus continue to pollute the planet excessively rather than clean up their production methods. The lower standards may arise because a country is eager to attract manufacturers to its territory and will offer greater latitude in environmental standards for the sake of financial gain, but the net effect on the planet is an adverse one that will harm the original country of the manufacturer in two ways; first, in the economic loss of the production and second because the pollution may eventually reach that region of the Earth anyway. As this pollution has the potential to be far greater because of the lax laws, the entire planet clearly suffers as a direct result of the differing standards in different locations.

9.7.2 Lack of enforcement The second problem is the lack of enforcement of standards even where they exist. There are several underlying reasons for this failure. First, there may be too few inspectors to carry out an effective policing operation, usually as a result of shortage of money. A manufacturer can pollute for a considerable period of time

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before there is any risk of being caught and, if the visit of an inspector is predictable, can take steps to ensure that laws are not being broken on the specific day when an inspection takes place. This lack of funding can only be rectified if society accepts that environmental protection is a vital feature of its continued healthy existence and applies pressure to its government to reflect this fact in providing adequate monitoring of potentially polluting activities. Lack of enforcement, however, can arise from other causes. The manufacturer may be part of a political lobby that threatens withdrawal of essential support if a government is too diligent in providing ecological protection, or there may be a system of ‘financial encouragement’ in operation that convinces inspectors to turn a blind eye to contraventions of the law. There may also be conflicts of interest, where the manufacturer’s activities are profitable for specific legislators, who thus have no wish to curb the harmful proceedings and can persuade their colleagues to agree with or accept their own lenient judgement. For all of these reasons, the planet will suffer if enforcement is neglected.

9.7.3 Penalties Even where enforcement is evident, though, there is still another reason why planetary damage continues to take place. In many cases, the penalty applied for flouting pollution laws is a relatively minor one that amounts to little more than a slap on the wrist. If manufacturers know that, even after being prosecuted successfully, they will only be assessed with a small financial penalty, they will continue to pollute and pay the insignificant fine on a regular basis. If the frequency of conviction is low, the fines can be written off as a business expense to be added to production costs and passed on to the end purchaser of the goods.

9.7.4 Non-standard definitions A further problem is the lack of agreement on what should actually be classed as illegal pollution. In most Western nations, heavy emissions (* A-1, A-2, A-3) from motor vehicles or from factories are regarded as unacceptable. The owner of the offending source of pollution is fined or, in the limit, forced to cease operation of the vehicle or plant. At the same time, the authorities in many countries of Eastern Europe, Africa, South America or Asia exhibit a total disregard for this type of source of harmful chemicals. Some cities in these developing nations are almost invariably shrouded in a toxic layer of fumes that would close down an entire municipality in the less tolerant countries. The excuse usually offered is that such nations are still catching up with their Western trade competitors and will not be able to afford the extra cost of dealing with the problem until their economies are considerably stronger.

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9.7.5 Emissions Emissions to water are the most obvious example of harmful substances released into the environment during textile production. Their importance can best be judged by the amount of work focused on this particular subject. A report35 confirms that textile mill effluents that are waste water discharges from wet processing such as scouring, neutralising, desizing, mercerising, carbonising, fulling, bleaching, dyeing and printing are indeed toxic (* W-2, W-3) and are likely to have immediate or long-term harmful effects on the environment. As a consequence of publication of this report, mills will face tighter effluent control regulations in Canada. Bradbury et al.36 suggest that ‘smart rinsing’ with careful attention to the location of inlet and outflow water in kier (a type of vat) dyeing can reduce rinsing times and provide more effective use of waste. Care in the selection of volume, flow rates and temperature is also needed. Reife and Freeman37 summarise the possibilities of pollution prevention by waste minimisation and source reduction in producing dyes or pigments. They include process optimisation, the substitution of toxic metals by less harmful ones and the replacement of toxic inorganic pigments containing calcium, lead, nickel or copper by other substances, then recommend the reuse of pollutants (such as aniline or phenols). Included in their article are comments regarding energy saving, safety and recycling opportunities that take advantage of reverse osmosis, ultrafiltration or hyperfiltration to produce reusable water. Other research papers tend to fall into one of two categories, the majority dealing with purification before release into streams or rivers and others in which the water is purified for reuse in processing operations. Frangi38 includes both areas from the viewpoint of environmental health and economics, noting four separate factors (management of reserves, quality of cleanliness for textile use, industrial treatment techniques and purification of waste) in the context of European Union regulations and the specific needs of particular processes. Peralta-Zamora et al.39 feel that extensive use of organic dyes is the main cause of textile environmental problems because they are recalcitrant carcinogenic (* W-2,W-3) materials. They study three processes for degradation of an anthraquinone dye: ozonation, enzyme and photocatalytic degradation with oxide of zinc or titanium. Ozone use produces complete decolourisation quickly, but no mineralisation; enzyme treatment gives quick decolourisation, but is limited to about 30% mineralisation. Photocatalysis produces complete decolourisation and mineralisation in about 60 minutes. Alho40 describes seven steps that can improve colour control in dyeing, thus avoiding unnecessary retreatments or premature discarding of goods. Holme41 suggests decreasing emissions at source by process optimisation. Kearns42 feels that tighter effluent controls must be adopted, while Porter43 recommends process automation as the key to waste water recycling and conservation of water and energy. Purification before discharge is attempted (often with only partial success) by using mechanical, chemical or biological treatments, alone or in combination.

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Bischefberger et al.44 provide an overview of the possibilities of waste treatment, avoidance and utilisation. Perhaps the simplest techniques for purifying effluents are represented by the work of Canziani and Bonono,45 who merely use a sand filter to achieve decolourisation, filtering and denitrification of dye effluent and work by Ibrahim et al.,46 who use a composite made from cross-linked wood sawdust for the same purpose. Papi c/ et al.47 use a coagulation/flocculation process to treat reactive dye waste water with ferric chloride as coagulant. They observe colour removal greater than 99.5% and determine that there is an optimum pH, in each case, which depends on the amount of coagulant added and the type of dye, but is within the range pH 2.55 to 2.70 for the conditions used in their test. Gonçalves et al.48 remove colour from waste by using an upflow anaerobic sludge blanket reactor, commenting that some azo dyes are readily reduced (with an average removal efficiency of 80 to 90%) but that the technique is ineffective for disperse dyes. Baughman49,50 finds that 91% of the copper ions from 12 direct dyes are removed from solution in 4 hours by sorption on a suitable sludge. Slater and Barclay51 investigate the possibility of using inorganic clays with other materials to absorb dyestuffs and other environmentally harmful substances from dye discharge liquors before discharge. They test 20 to 30 combinations and establish removal efficiencies from very low to over 90%. Although such chemical and biological techniques are relatively more common, there are, nevertheless, also a few miscellaneous instances of attempts to remove pollutants before discharge. All of these are described in Section 9 of the Appendix. Air emissions should also be mentioned briefly. These can arise from many segments of the industry and are dealt with to some extent elsewhere in this book, but their removal is often attempted before discharge to air or water takes place. One author52 describes an exhaust clearing system that provides recovery of waste process heat, reducing the need for fuel and hence lowering production costs. Another anonymous author53 reviews the needs for a satisfactory air cleaning installation for use in filtration, waste handling and air conditioning requirements. Freiberg54 notes that, until recently, it was impossible to operate air cleaning systems efficiently because they suffered either from external high energy consumption, or from high water consumption, or from considerable maintenance needs. He claims that it is now possible to operate modern cleaners efficiently and at lower costs, because they include an option to omit exhaust air cleaning where it is not needed. He then describes three types of successful cleaners.

9.8

Recycling

A contemporary preference in many industries is to try to minimise resource depletion and pollution production as much as possible by reusing or recycling materials. Several efforts in this direction are described in Section 10 of the Appendix. As may be seen there, the matter of recycling can be extended beyond

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water treatment to all materials used by the industry. Benisek55 reports a conference in which a separate section is devoted to recycling, emphasising the importance of environmental concerns in textile processing. Papers presented include those dealing with biological treatment of waste water, digestion techniques, neutralisation of alkaline effluents, reduction of mothproofing effluents, spray dyeing and fibre identification. One of the current aims in the attempts at cutting down pollution is to recycle (or remove from another recycling operation) chemical agents, many of which include compounds that are notoriously difficult for the environment to handle. The recycling of actual fibre or fabric materials is also being regarded as a useful course of action. Kohler et al.56 report that there are 127 000 tonnes of waste generated by the German textile industry annually, then deal with the topic of recycling edge strips, or the whole article, from quilted goods. Raje and Rekha57 review work carried out on the regeneration of silk polymer from waste or otherwise unusable silk fibres, while Diounn and Apodaca58 even suggest using the internet to arrange for exchanges of cotton waste, thus reducing disposal costs. Polyester seems to be of interest, too, as several papers are devoted to the fibre. One possible reason is the report, publicised by Methner-Opel,59 that old clothing is to be treated as refuse in proposed German legislation, which means that manufacturers will either be required to ‘pay’ (meaning pass on to the consumer) the cost of future disposal or establish a returns policy. Roberts60 also states that second-hand clothing might possibly become designated as waste and laments the potential loss of exports and jobs as well as the overflowing landfills, the absence of cheap clothing for developing nations and the revenues lost by charity shops. Mannhart61 gives details of the technology for recycling polyester bottles into filament yarn and Hansler62 notes that the recycling of polyester containers in Europe increased by over 40% in one particular year. Goynes63 describes a process of recycling polyester fibres and, after blending them with greige cotton, using them to manufacture non-woven blankets by needle-punching. Measurements of air permeability, thickness, weight, stiffness, bending and compressive rigidity, tensile strength and flammability are carried out, as also are evaluations of thermal conductivity or transmission, differential thermal analysis and thermogravimetric analysis. The results confirm that the technique can yield a low-cost lightweight blanket with good handle in a heather shade that can be deepened by dyeing if desired. The blend used, of 30% cotton and 70% reprocessed polyester, produces an acceptable cover for military, medical or recreational use on a short-term basis. One report64 indicates that yarn-dyed fabrics from recycled polyester bottles can be made into uniforms. Biodegradation, also mentioned in the Appendix (Section 9), is currently in the ascendancy as a means of combating pollution. However, the main thrust in the recycling effort currently appears to revolve around the idea of recovering new raw materials from carpets. This is reportedly a big issue;65 it is obvious why when one considers the magnitude of the problem, because the rate of disposal is reported66 at four billion pounds (that is, about 1.8 million tonnes) per

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year in the USA alone. Again, Section 10 of the Appendix should be consulted for further details of research taking place in this topic area.

9.9

Pollution measurement problems

An important reason why environmental efforts may not be as effective as we would like is the fact that the inability to measure pollution accurately may lead to lenient sentences. It is a fundamental tenet of the justice system of most countries that innocence is to be assumed until guilt is proved. If the legislation depends on a quantitative assessment of the amount of pollution produced, and this amount cannot be measured precisely, there is no point in taking an offender to court unless the amount of pollution occurring is so far in excess of the legal limit that there can be no possibility of a mistaken measurement being used as a defence. Thus, pollution that exceeds considerably the amount permitted may well be overlooked, rather than risking losing a case on insubstantial legal grounds.

9.10

Environmental auditing

In an effort to minimise the difficulty mentioned above, the technique of environmental auditing has been developed. The major benefit of this action is that it enables changes that were unexpected to be detected and, once the difference has been explained, it can pinpoint a part of the process where pollution is being produced or undesirable additives are being taken up by the textile goods. An investigation can then be carried out to detect the source of the problem, which can subsequently, it is hoped, be corrected. There are, however, some difficulties that can arise.

9.10.1 Theory In theory, the environmental audit process measures (by weighing) every component that enters a process and every one that leaves it. Thus, if (say) six raw materials are used to make some type of product, then the weight of all six materials entering is compared with the weight of product obtained. There will, in general, be a difference in the two readings. It represents the occurrence of one or more of several possibilities. If there is a negative difference (i.e. the weight of the product is less than the sum of the weights of the components), then an unexplained loss of material has taken place. This could be accounted for by an evolution of a byproduct (an undetected gas, liquid or solid that has escaped the measurement process) resulting possibly from burning of fabric, evaporation of water or a difference in atmospheric conditions at the times the two sets of measurements were taken, or fibrous material that has been lost in the form of fly. If, on the other hand, there is a positive difference (i.e. the weight of the product is greater than the sum of the weights of the components), then an unexplained gain of material has

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taken place. Possible reasons for this include (as before) a change in measurement ambient conditions, a chemical reaction with the air or with moisture or the accumulation of foreign matter (such as dirt or an adsorbed chemical) on the fibres. Smith and Lee67 identify trace impurities that can cause pollution, such as fibres, metals, volatile organic compounds (VOC) or toxic organics. The determination of trace impurities is difficult and one important outcome of the work is the evaluation of analytical methods for cotton, wool, polyester, acetate and nylon 6 to determine how effective they are. Kalliala and Nousiainen68 develop an environmental index model based on life-cycle assessment to determine the total environmental impact for a comparison that includes energy in laundering a range of fabrics. They find that, for instance, 100% cotton needs 20% more energy in laundering than does a 50/50 cotton/polyester blend.

9.10.2 Eco-balances Schmidtbauer69 recommends the increased use of eco-balances as a tool for comparing the environmental impact of regenerated polymers, using viscose rayon as an example. He demonstrates its usefulness by tracing the impact of rayon production from beech trunk to fibre, thus achieving a life-cycle balance for rayon from its forest origins to the final product and establishing the ecological aspects of rayon manufacture. He describes special processes to reduce pollution and protect the environment and notes how waste can be converted to valuable secondary materials. In his presentation, he includes a material and energy balance for pulp and viscose production, quotes emission parameters (such as chemical or biological oxygen demand, adsorbable organohalides, sulphur dioxide and hydrogen sulphide emission) and discusses the environmental impact of forestry. He concludes that viscose production is relatively clean in comparison with that of natural or synthetic fibres.

9.10.3 Accuracy The first drawback of the practical aspects of an environmental audit process concerns the matter of accuracy. The technique demands very precise measurement of the various components to ensure that the materials present in all parts of the process are detected. If an operator fails to note the existence of one type of material, or fails to measure its presence accurately in a quantitative assessment, then an error is introduced that indicates the presence of pollution in the form of lost or acquired mass. Much time can then be wasted in the effort to find this nonexistent pollution, adding to the cost of production. It is possible, too, for workers to falsify the results in the belief that management representatives want to hear good news, or may blame the workers for the existence of a large quantity of pollution. The discrepancy may not come to light until an inspector checks the audit figures, finding that unreported defects are in fact present. He is then likely

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to levy on the company a fine or other penalty that may cost them more than would have been needed to pay for fixing the problem in the first place if they had been made aware of it.

9.10.4 Inevitable pollution There may also be situations where, no matter how good the audit may be, the detected presence of pollution cannot be rectified. If, for example, a vital process inevitably produces large quantities of an undesirable by-product, the government (or society) may be faced with the choice of either accepting the harmful substance or agreeing not to need the actual product. If the consumer or society stipulates that the product is indeed essential (as in military or space applications, for example), then no amount of auditing or imposition of fines will be able to solve the problem.

9.10.5 Pollution quotas It is for situations of this kind that the idea of trading or buying pollution quotas has been developed. The principle of this activity is that a company producing less than its permitted quota of pollution can ‘sell’ the remainder of its unused quota to a company with excessive pollution. The latter company is then allowed to exceed its own pollution quota and is thus paying for the privilege of producing this excess pollution. This arrangement exempts the ‘dirty’ company from prosecution and enriches the ‘cleaner’ company, but does little or nothing in the way of helping the environmental overload. One of the worst aspects of this trade is that, as more companies are developed, there is a need for added pollution permits to be issued; we never think of compensating for the extra load by reducing the quotas issued to existing companies to ensure that the overall level of pollution does not increase. The effect on the planet needs no amplification; a sane society would abandon without hesitation this sacrifice of ecological preservation in favour of economic gain.

9.10.6 Vigilance A further difficulty is the need to maintain constant vigilance on processing to ensure that new problems (or the same ones) do not crop up at a later date. This monitoring tends to be an expensive activity and one in which there is seldom, if ever, any payback to add to the profit side of the books. If detection of a problem leads to a solution that saves money for the manufacturer, then the results are welcome. If, on the other hand, all that is found is a need to remove the pollution (at a cost, naturally) without any financial benefit, then the manufacturer is likely to be much less willing to participate in the altruistic activity of helping to save the planet! One point that is never made, however, is the fact that the cure for an

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environmental problem may in fact be environmentally harmful in itself. If, for instance, a specific machine or reagent is needed to remove a pollutant, then the cost of manufacturing that machine or reagent provides an ecological burden that is usually ignored. The result of its use, too, may leave a pollutant of a different kind; absorbing an acid gas in a mill chimney stack by means of scrubbing through a water trap, for instance, leaves an acidic solution to be discharged to the local water system. If an alkaline medium is used to absorb the acid gases, or to neutralise this solution, then a salt is produced, to be deposited on the land. In other words, we are not removing the pollution, but merely changing its form by disguising it, usually to meet some form of restrictive legislation. Thus, because the total effect on the planet is undiminished by this change in form, many of the efforts put forth are ecologically useless. This is true at all stages in the manufacturing process; wherever a problem is ‘solved’ by any method other than reduction of consumption or production, the ‘solution’ adopted leaves behind a residue that often creates an ecological nightmare when disposal is attempted. Another aspect needs to be considered. The fact that a short life expectancy for a textile product can add to the pollution load for which the textile is responsible has been mentioned several times. In the remainder of this book, the ways in which such a reduction in usable life can occur are examined. Once again, environmental factors are of crucial importance.

References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Anon., Colourage, 1998, 45(9), 67–69. Anon., Japan Textile News Weekly, 1998, 24(34), 1–2. Orzada, B.T., Int. J. Clothing Sci. Tech., 1998, 10(6), 10–12. Cunho, R., Andrassy, M., Pezelj, E. et al., Int. J. Clothing Sci. Tech., 1998, 10(6), 96–98. Muirhead, S., J. Soc. Dyers Colourists, 1998, 114(9), 236–237. Benisek, I., Textile Horizons, 1999, February, 24–25. Benisek, L., Textile Horizons, 2000, February, 22–24. Smith, B., Am. Dyestuff Rep., 1998, 87(9), 28–34. Gale, M.E., Shin, J. and Bide, M., Textile Chem. Colorist, 2000, 1, 28–31. Gale, M.E. and Bide, M., Textile Chem. Colorist, 2000, 4, 32–35. Gale, M.E. and Bide, M., Textile Chem. Colorist, 2000, 8, 75–78. Barton, J., Int. Dyer, 2000, 10, 24–26. Arias , J.M.C., Revista Quim. Textil., 1999, 142, 52–55. McCarthy, B.J. and Burdett, B.C., Rev Prog. Coloration Rel. Topics, 1998, 28, 61–70. Achwal, W.B., Colourage, 1998, 45(9), 43–45. McKenzie, J., Textile Horizons, 1999, March, 16–17. McKenzie, J., Textile Horizons, 2000, May–June, 10–12. McKenzie, J., Textile Horizons, 1999, March, 16–17. Elsasser, N., Maetshke, O. and Wulfhorst, B., Melliand Textilber., 1998, 79(10), 768 771. 20 Shaw, T., J. Soc. Dyers Colourists, 1998, 114(9), 241–246. 21 Dixit, M.D., Colourage, 1998, 45(12), 43–44 and 46(2), 45–46.

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Shaver, J.A., Textile Chem. Colorist, 1999, 31(5), 27–30. Battersby, M.E., Am. Textile Int., 1999, 28(3), 96–98. Moore, M.A., Money, A. and Orzada, B., Textile Chem. Colorist, 1999, 31(4), 27–31. Wakeling, A., Int. Dyer, 2001, 9, 32–33. Hohn, W., Textilveredlung, 1998, 33(9–10), 24–28. Anon., Int. Dyer, 2000, 12, 3. Russell, E., Int. Dyer, 2001, 5, 6–9. Phillips, J., Textile World, 2002, 152(2), 36–38. Baker, R.V., Highs, S.E. and Parnell, C.B., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 463–468. Rey, I., Textile World, 1998, 48(11), 4–9. Holme, I., Int. Dyer, 1998, 183/(2), 63–64. Sedlak, D., Dumler-Gradl, R., Thoma, H. and Vierle, O., Chemosphere, 1998, 37(9–12), 2071–2076. Carroll, W.F., Berger, T.C., Borelli, F.E. et al., Chemosphere, 1998, 37(9–12), 1957– 1972. Anon., Can. Textiles J., 2000, September/October, 8. Bradbury, M., Collishaw, P. and Moorhouse, S., J. Soc. Dyers Colourists, 2000, 5/6, 144– 147. Reife, A. and Freeman, H.S., Textile Chem. Colorist, 2000, 1, 56–60. Frangi, C., Tinctoria, 1998, 95(10), 38–44. Peralta-Zamora, P., Kunz, A., Gomas da Moraes, S. et al., Chemosphere, 1999, 38(4), 835–852. Alho, E., Textile Horizons, 2001, May–June, 17–20. Holme, I., Int. Dyer, 1998, 183(12), 63–64. Kearns, G., Can. Textiles J., 2000, 5, 10–16. Porter, J.J., Textile Chem. Colorist, 1998, 30(10), 9–15. Bischefberger, C., Wille, G., Heindorf, W.-E. and Pawlitha, D., Melliand Textilber., 1999, 80(4), 308–309. Canziani, R. and Bonono, L., Water Sci. Tech., 1998, 38(1), 123–132. Ibrahim, M.A., Abo-Shosha, M.H., El-Sayed, M.Z. and El-Alfy, E., Colourage, 1998, 45(annual), 159–164. v / c, A.L., J. Soc. Dyers Colourists, 2000, 11, 352–358. Papic,/ S., Koprivanoc, N. and Bozi Gonçalves, I.M.C., Gomes, A., Brás, R., Ferra, M.I., Amorim, M.T.P. and Porter, S., J. Soc. Dyers Colorists, 2000, 12, 393–397. Baughman, G.L., Textile Chem. Colorist, 2000, 1, 51–55. Baughman, G.L., Textile Chem. Colorist, 2000, 9, 48–53. Slater, K. and Barclay, S., Int. J. Clothing Sci. Tech., 1998, 10(6), 73–74. Anon., Int. Dyer, 1999, 184(3), 33. Anon., Textile World, 2002, 152(4), 42–44. Freiberg, H., Am. Dyestuff Rep., 1998, 87(8), 23–27. Benisek, L., Textile Month, 1999, August, 32–34. Kohler, F., Nendel, W., Vetterman, G. and Wagenbreth, C., Melliand Textilber., 1999, 80(6), 554–555. Raje, S.S. and Rekha, V.D., Man-Made Textiles in India, 1998, 41(6), 249–254. Diounn, M.M and Apodaca, J.K., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 373–379. Methner-Opel, B., Bekleiding Wear, 1998, 50(20), 44–46. Roberts, S., Wool Record, 1999, 158(1), 45.

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Mannhart, M., Synthetic Fibres, 1998, 27(3), 9–12. Hansler, H., Textile Horizons, 1999, March, 24–25. Goynes, W.R., Textile Chem. Colorist, 2000, 1, 40–45. Anon., Japan Textile News Weekly, 1999, 25(19), 4–5. Anon., Int. Carpet Bull., 1998, 292, 2. Reallf, M.J., Ammons, J.C. and Newton, D., Polymer-Plastics Tech. Eng., 1999, 38(3), 547–567. 67 Smith, B. and Lee, J., Am. Dyestuff Rep., 1998, 87(8), 9–17. 68 Kalliala, E. and Nousiainen, P., 79th World Conference of Textile Institute, 10–13 Feb 1999, Chennai, India, Vol 2, 37–49. 69 Schmidtbauer, J., Asian Textile J., 1998, 7(10), 59–69.

10 Effects on textiles of natural exposure

10.1

Influences

If this were a work of science fiction, the remainder of the book would have a title like The Revenge Of The Planet to express its focus. Until now, we have seen how the production and use of textiles affect the environment. This section is intended to illustrate the way in which textiles and their production are influenced, in turn, by the environment. The first survey will involve the degradative effects impinging on a textile used under normal circumstances in the natural environment. This will include exposure to air or moisture in the atmosphere, radiation striking the fabric from its surroundings, mechanical stresses and combinations of two or more of these effects.

10.2

Degradation

When a textile product is placed into service, it has a specific set of attributes, designed for its intended end use. From that point on, however, it is subjected to the effects of the ambient conditions under which it is used. In virtually all cases, these conditions bring about adverse changes in the product, a process usually classed under the general term of degradation. All textiles (and almost all other materials) are victims of this type of change. The normal course of events includes a decrease in properties, which may be gradual or sudden, depending on the circumstances, to make the material less suitable for its intended purpose. This process continues until, after a period of time during which the changes occur sporadically as a result of the continuing presence of the sources of degradation, the material reaches a state of unsuitability at which it can no longer be used at all for that purpose. There are so many feasible reasons why the changes might occur that it is almost impossible to allocate any specific change to one source of harm. What has to be recognised is the fact that a variety of degradative mechanisms, all operating in conjunction, will always be present in a particular situation and will bring about the 115

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loss of properties that results in failure of the textile product. All that can be done is to examine in turn each of the potential sources of harm and establish how its effects are produced, then decide which combination of mechanisms is present in each specific situation and predict what the overall effects of exposure to the combination will be. We should also not forget that degradation may affect the equipment used to produce the textile product, not merely the product itself. Environmental factors can be harmful to all materials, not just textile ones, and some of those affected may indeed be a part of the production process.

10.2.1 Molecular characterisation Degradation occurs because of the destruction of a part of the molecule of which the structure is made. In general, the region in which change takes place is governed by the level of energy applied to the structure. If a small amount of energy is absorbed in the molecule, the effect observed will most probably be in the side chains. These may be modified chemically to alter, for instance, the type of end group present in them. The molecular structural consequences may or may not be detected as a loss of a specific property, but there will normally not be too major a change observed. If higher energy levels are encountered by the structure, then the entire side chain in which the end groups are located may be split off from the rest of the molecule, with a more obvious loss of property. Finally, if the impinging energy level is even higher, there may be a scission of the entire main chain, with a massive loss of properties that automatically renders the product useless. The actual level of energy that governs where changes occur and what their magnitude is likely to be will naturally depend on individual circumstances, with an energy level that would bring about total decomposition in one type of molecule causing only minor loss in another, more tightly bonded one.

10.2.2 Time dependence We have to recognise that textile degradation can take place at many different points in the lifetime of the material. Even during the manufacturing process itself, there may be adverse changes that occur. Once the textile is made, losses in property can be evident merely as a result of storage. It is, though, during use of the product that the most significant changes are brought about, mainly because the textile would be rejected as a failure if too much degradation had resulted from the former two stages (production and storage) of its life. Whenever and wherever degradation happens, it should be stressed that, if a major loss of property occurs prematurely, the product will be discarded prematurely, thus bringing about an early load on the environment, leading squarely back to the same situation of an adverse ecological effect being created once more.

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Atmospheric influences

10.3.1 Oxygen The first and most obvious source of potential harm is the atmosphere to which a textile product is exposed. There are two crucial components that are always present, air (especially oxygen) and water in the form of moisture vapour. Both are omnipresent and likely to impinge on the textile goods no matter where they are used (unless their function is in a space application). For the textile product to be a successful one, the effects of exposure to atmospheric air should be negligible. If oxygen is going to have any effect at all, it must be by the process of oxidation, in which a change in structure takes place. There are many examples that can be quoted to illustrate the type of reaction that could occur. The change may be one in which an oxygen atom is added to the molecule (e.g. when an aldehyde side chain in a molecule is oxidised to an acidic one) or in which a valency state is changed (e.g. when a ferrous ion in a side chain is converted to a ferric one) or in which a side chain undergoes scission (e.g. when combustion also takes place).

10.3.2 Moisture Somewhat surprisingly, oxygen at normal concentrations in the atmosphere has virtually no effect on textile products, or on the machinery used for their manufacture as long as moisture is absent. In the presence of water, though, the situation can change drastically. We should accept without question that moisture is almost always present in textile (or other biological) products; the exceptions are those in which the structure is completely hydrophobic, textile examples including such fibres as carbon and polyolefins. For those fibres that are hydrophilic, excess moisture can enter the structure from an atmosphere of high humidity and cause molecular bonds to break open. Even fibres with very low moisture regain can be affected, because moisture can be adsorbed (i.e. held on the surface of the fibres) so that its presence is potentially able to bring about changes. There are two common types of effect in textiles that can occur as a direct result of moisture in the atmosphere. If relative humidity is high, the added moisture within the structure can cause dimensional changes. Cockling and swelling may take place, adversely affecting the shape of a fabric and rendering its use in making garments or other products limited. Conversely, in conditions of low humidity, some of the natural moisture within the structure may be lost, leading to possible brittleness or cracking of fibres during mechanical handling. Other effects associated with water in non-textile materials, such as loss of water-soluble components or the freeze–thaw phenomenon, can occasionally arise in textile products, but the frequency and importance of these unusual occurrences are so small that it is safe to ignore them in normal use on the Earth’s surface. In some applications (protective clothing for space, fire-fighting or marine oil-rig uses, for instance) they may possibly become crucially important and so should not be forgotten completely.

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The type of effect that results from atmospheric exposure depends, as always, on the situation. There may be a loss of colour, manifested as fading, or a spoilage of colour as a consequence of the running of dyestuffs not intended for exposure to large quantities of moisture. There may be watermarking of a fabric as a result of salts or other chemical reagents present that are allowed to stain it by the sequential evaporation and rewetting of the textile surface. Weakening of the structure, or swelling to distort a fabric, are also possible consequences. In textile production machinery, the combined effect of air and moisture can be drastic. Corrosion of metals is one of the most pervasive and troublesome problems that structural or mechanical engineers have to face. The most usual example, the rusting of iron, is a leading cause of forced early scrapping of machinery which then despoils the land. In an effort to prevent corrosion, literally millions of pounds are spent annually in making special materials, such as alloys that can resist the effects of air and moisture, as well as in developing and using protective coatings such as paint, varnish or other agents of surface isolation. Even before rejection as a result of corrosion is necessary, problems can be encountered. The existence of machine rust can bring about staining on a textile product, staining that may be difficult or impossible to remove; even if the soiling can be eliminated, a considerable cost is added to the goods by the removal process. Corrosion can also bring about dimensional changes as a result of a metal axle or shaft warping and wear on a bearing or other component. This flaw will cause defects to arise in the material being processed, thus bringing about the need to discard or scrap it.

10.3.3 Chemical substances There are other chemical substances present in the atmosphere in addition to oxygen and water. Nitrogen is the main constituent of air, carbon dioxide is universally present, and there are various gaseous, liquid droplet or particulate impurities derived from human household or industrial sources that can affect materials exposed to them. Nitrogen is an inert gas and has little or no effect on non-reactive materials like textiles. Carbon dioxide and the impurity materials are generally of a type that falls into one or other of the substances to be covered in the remainder of this book (such as acids or solvents), so can be omitted at this stage. We should not forget the simple matter of dirt present in the air. Grime from industrial air pollution or from coal-burning fires has long been the bane of many a washing day, when clothes are hung out to dry and come into contact with air that is contaminated by tiny particles. These may also gather on the skin near an air/ fabric interface, especially where garments come into contact with the body tightly, and produce soiling of the cloth there. Chrobaczek et al.1 note that the interaction between soil and textile depends on many physical and chemical properties. They discuss the processes involved, the various parameters influencing soiling behaviour and the topic of antisoiling finishes, including the classic ones

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with fluoropolymers, the application of silicone-based softeners and the use of combinations of the latter two types of substance.

10.3.4 Other sources Textiles in the normal atmosphere almost inevitably encounter other sources of degradative stress besides the ones mentioned above, the most notable being that of radiation, first from the sun and then from other sources. Exposure to heat can occur, either accidentally or as a deliberate part of the function of the textile use, as also can contact with chemicals. Each of these subjects will therefore be considered separately in the remainder of the book.

10.4

Radiation

Radiation is a term given to electromagnetic energy emanating from various sources (light, sound, ultraviolet, etc.) over a wide spectrum of frequencies. Not all of them have an effect on textile materials or on other materials used in the production of textile goods, although we are beginning to suspect that some relatively small-scale effects may exist where none were believed to do so by former investigators.

10.4.1 Frequencies The range of frequencies that can be attributed to radiation extends from about 1023 Hz (i.e. at a wavelength of about 3 × 10–15 m) to about 1 Hz (a wavelength of about 3 × 108 m). In this range, the regions of most importance to textile degradation are approximately in the middle of the range, including the optical (at frequencies of about 4.3 × 1014 to 7.5 × 1014 Hz), ultraviolet (at frequencies of about 7.5 × 1014 to 3.8 × 1017 Hz) and infrared (at frequencies of about 1.5 × 1011 to 4.3 × 1014 Hz) frequencies. The mechanisms of change are similar in all cases; the radiation impinges on the object and its energy is absorbed by the latter, bringing about some kind of degradation. The amount of energy contained within a unit particle (a photon in the case of electromagnetic radiation) is given by the expression E = h.ν where E is the mean energy of a photon in electron volts (eV), ν is the frequency of radiation in hertz and h is Planck’s constant, with a value of 6.63 × 10–34 J-s. It follows that energy is proportional to frequency, so that an ultraviolet photon has higher energy than an optical one, which in turn has higher energy than an infrared one. Therefore, we can expect that ultraviolet radiation will be more damaging than optical radiation, other things being equal, and this is generally borne out in practice. There are two additional considerations to take into account. The first of these is the amount of radiation falling on the textile material. Clearly,

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if a fabric is exposed to a higher dosage of radiation (of whatever kind) it is likely to experience higher degradation than it would if it were exposed to a lower level of the same radiation. A piece of cloth stored in the dark, for example, is likely to deteriorate less rapidly than one exposed to bright sunlight. Millington2 compares the effects of ultraviolet and gamma radiation on wool keratin. At high gamma radiation levels, burst strength is decreased by about 15%, but no change is evident with comparable high levels of ultraviolet exposure. There is a complex colour change with gamma radiation, but an easily explicable one with ultraviolet exposure. In addition, gamma radiation causes yellowing that is difficult or impossible to remove with peroxide bleaching and produces, as Millington expects, no permanent set (irreversible change of shape or form). With ultraviolet radiation, peroxide bleaching brings about an increase in colour yield on printing. The author suggests as explanation for these phenomena the fact that gamma radiation causes damage to the whole fibre, while ultraviolet rays cause damage only on the surface.

10.4.2 Resonance The second contributory factor is more complex. Energy absorption takes place at specific sites within the molecule, these usually being identifiable as certain bonds. All bonds are in constant movement at temperatures above absolute zero and these movements occur at fixed frequencies. If the frequency of oscillation of a particular bond happens to coincide with the frequency of the radiation falling on the material, then the bond will be forced into enhanced oscillation (a process known as resonance). This is because the ‘kick’ caused by the arrival of every photon of energy will coincide with the beginning of a period of oscillation and each ‘kick’ will add some impetus to the motion. This situation is analogous to the way in which a child’s swing can be made to go higher by means of a small push applied at the crucial moment when the swing begins to reverse its direction. By chance, the frequency of oscillation of many carbon–carbon double or triple bonds happens to coincide with the natural frequency of radiation in the optical or ultraviolet region of the electromagnetic spectrum, so that energy at the characteristic frequency of this portion of the radiation is absorbed heavily and is likely to to be very damaging. Textile materials tend to contain a lot of carbon–carbon bonds, many of them (especially in the structure of dyestuffs) being compound bonds. Thus, in essence, the total energy level absorbed by a textile product may often be greater than the molecular structure of the fibre or dyestuff molecules can tolerate without suffering some bond breakage. In general, the three types of radiation mentioned above occur in nature, since they are all derived from sunlight. The amount of solar energy falling on our planet3 (taking into account the fact that there is some loss by absorption in the atmosphere) is about 1 kW/m2 over the entire surface of the earth, averaged on an annual basis. Bonding energies generally lie4 in the range from 600 to 1500 kJ/mol for molecules commonly found in textiles, so exposure to solar radiation (assuming

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all the energy falls uninterrupted on the fabric) might be expected on average to break all the bonds in a mole of material every second. Obviously, this does not happen, or textiles would disintegrate at a rate almost as fast as we could make them. The explanation is simple; the energy does not all impact exclusively on the bonds, but is absorbed by all parts of the structure, including those regions where there are no bonds that can be broken by the specific radiation falling on them. Nevertheless, the concept does give some indication of the high rate at which damage can potentially be done by incident radiation.

10.5

Changes occurring

10.5.1 Visible In practical terms, the changes can be categorised in two different types of observation, a visible one and a mechanical one. When bonds break, the first indication that damage has occurred is often a colour change. A dyestuff may fade, for example, or a fabric may turn yellow. These symptoms arise because the chemical substance that has been damaged has undergone a change in bonding type. Bonds that originally absorbed a particular region of the optical spectrum (and hence gave rise to a colour representing the portion of the light not absorbed) have been destroyed, so the preferential absorption no longer occurs and the material’s colour is lost. Rastogi et al.5 study the photofading of reactive dyes on silk and cotton, finding that fading depends on the interaction between fibres and dye molecules, in that better interaction produces better fastness. They propose explanations in molecular terms for the fact that reactive dyes are better for cotton but poorer for silk in comparison with unreactive ones. Oda6 tries to improve the light fastness of natural dyes with nickel sulphonate complexes used as singlet oxygen quenchers, which he finds to be much more effective than conventional ultraviolet absorbers, especially in the presence of hydroxyl groups. Alternatively, the change may produce new types of bond that absorb preferentially in other regions of the spectrum. If absorption is greatest in the blue region, for example, the remaining non-absorbed colour, yellow, is emitted and can be seen in the shade of the fabric viewed.

10.5.2 Mechanical The second type of change is usually representative of more intense bond destruction, as discussed earlier in this chapter. When a bond breaks, the material loses a minute amount of its mechanical integrity and, if enough bonds are destroyed by the incident radiation, the strength imparted to the structure as a whole by the bonds can deteriorate. In consequence, tensile, tear or burst strength can be reduced, so that the material breaks if a load is applied to it. In general, textile goods tend to wear out most frequently under the influence of abrasive

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force, as a result of the lowering of abrasion resistance resulting from the accumulation of small fabric integrity losses over an appreciable surface area. The fabric may also become brittle as a consequence of the molecular changes induced by the radiation, again causing it to disintegrate, this time by a cracking process.

10.6

Infrared radiation

The third type of radiation (in addition to visible and ultraviolet) emitted in large amounts by the sun, infrared, tends to be much less damaging to textiles. This is for a combination of two reasons: first, the frequency (and hence the energy) is much lower and second, it does not coincide with the natural vibration frequencies of bonds present in the molecules, so the material is much less susceptible to destruction from this source. Infrared radiation, in fact, is used as a source of drying energy for textiles; it is, though, not entirely harmless, as will be shown in detail later in the book.

10.7

Other types of radiation

These are not, however, the only types of radiation present in the output from the sun that falls on the Earth. Evidence is slowly accumulating to show that there are many other different types of radiation within the solar electromagnetic spectrum that are a constituent of the overall emission output from our star. They include (in descending order of frequency and hence of energy) γ-rays, X-rays, microwaves and radiowaves; the former two are at higher frequencies than the three common solar ones already mentioned, while the latter two are at lower ones. There are also present minute nuclear units such as α-particles, neutrinos and other exotic products of nature, currently of interest only in the realms of high energy physics. Fortunately for the long-term stability of terrestrial materials (and hence for a healthy environment) all of these occur naturally only in insignificantly small amounts, or are of frequencies not causing major damage to materials, or pass through all objects (including the earth itself and even its human inhabitants) without leaving any trace of their passage or bringing about any detectable change. They would not be worth a mention in the context of this book at all if it were not for the fact that they have been harnessed by human beings in textile usage and thus become less insignificant. Microwaves are used, for instance, in drying equipment, and will be discussed again later, while X-rays, α-rays, β-rays and γ-rays are finding applications as diagnostic tools for elucidating textile structures. Ultrasonic vibrations, too, though not usually defined as radiation, are used to disintegrate fibre samples into fragments for analytical purposes. To date, radiowaves and neutrinos have not been harnessed by the industry, but this situation could change as knowledge about their production, properties and control is accumulated.

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10.7.1 Diagnostic uses The diagnostic uses of some of these types of radiation can be mentioned briefly at this point. X-ray diffraction is a familiar means of identifying crystal structures in polymers, while γ-rays are eventually likely to take over this function completely, in view of their higher frequencies (and hence energy capabilities and higher resolving power) at some time in the not-too-distant future. One of the uses of α-rays and β-rays is to bring about radioactive labelling of goods and there are some devices (such as textile thickness testers, electrostatic measurement equipment or evenness monitors) that have found application, at least in experimental situations, by dint of such labelling. All of these energy sources are artificially augmented above their naturally occurring levels, simply because the sensitivity of the apparatus making use of them would not be sufficient otherwise. As a result, there are precautions that have to be taken to prevent damage to the textile goods exposed to all of them, as well as (in some cases) to the human beings working in the local environment. Any exposure at too high a level would tend to degrade the textiles, in the same kinds of way as those discussed above in connection with the more conventional forms of radiation, because bond disintegration could occur, if the material happened to be susceptible to the amount of energy falling on it. Finally, it is vital to note that exposure to radiation is virtually inevitable for textile materials, even where they are not placed into service. Fabrics cannot easily be isolated from natural sources, except by sealing them into a light-proof chamber, and degradation cannot be avoided in any other way. In all other forms of degradative decomposition (thermal, chemical, mechanical, microbiological) to be dealt with in this book, it is necessary for the textile goods to be placed into service in some way before changes occur; radiation is thus unusual in this respect and should be recognised as such. In fact, this is an almost impossible situation to envisage; textiles are seldom, if ever, encountered in total isolation from their surroundings and everyday use normally subjects them to other stresses, of which the most obvious is mechanical action.

10.8

Mechanical action

10.8.1 Mechanical stresses Textile materials are subjected to mechanical stresses throughout their lives, during production as well as during use. Stresses may be imposed in any of several modes, as shown in Fig. 10.1; in all the diagrams, the manner of application of the force changes the object under stress from its initial (shown by dotted lines) position to its final (full lines) one. The application of tensile force (Fig. 10.1a) stretches the fibres or fibre assemblies in a lengthwise direction. Compressive force (Fig. 10.1b) pushes them together in a crushing manner. Torsional force

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10.1 Modes of mechanical stress application. (a) Tension, (b) compression, (c) torsion, (d) bending, (e) shear.

(Fig. 10.1c) applies a twist that causes rotational movement to take place. Bending force (Fig. 10.1d) brings about a bowing of a component which had previously been linear. Shear force (Fig. 10.1e) causes a distortion in the plane that deforms a material sideways. These forces are seldom, if ever, applied in isolation. Most mechanical action involves the presence of two or more stresses, or even types of stress. In the tearing process, illustrated in Fig. 10.2, possibly the simplest example of compound force application, tensile forces are applied in a non-collinear manner to a fabric, with the result that the direction of deformation, and hence destruction, is perpendicular to the line of application of the two forces. In bursting, there are many forces involved, the main ones being tensile ones applied sideways to the surface of a fabric under stress combined with compressive forces normal to this surface, possibly with the addition of shear, tear and bending ones as well, so resulting in its near-violent collapse.

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Directions of force application

Direction of tearing

10.2 Mechanical forces present in tearing.

Abrasion is a more complex, but very common, mode of mechanical action. In it, a textile material in contact with the surface of another material is gradually or rapidly destroyed by having fibres dragged out or broken as a result of frictional resistance to movement. As is obvious by elementary consideration of the process of abrasion, the types of force applied can be any of the five listed in the opening paragraph of this section. A fibre may be snagged on the foreign surface and be pulled out of the structure by tensile force. It can be squashed between the foreign surface and the body of the textile. It can be subjected to torsion, bending or shear as the textile twists, bends or is pulled sideways in a specific zone during its passage across the surface. It should always be remembered that, when mechanical action destroys a fabric, the mechanism is the familiar one we have already encountered earlier in this chapter. Minor application of small levels of force will cause a distortion of the structure, but the latter will recover its original state on relaxation of the stress. If the applied force is somewhat larger, then changes in the end-group chemistry are potentially able to occur, with atoms or groups being released from the molecule. Still more stress can cause loss of the entire side chain and very high-level stresses can bring about chain scission in the carbon–carbon backbone of the fibre molecules.

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One important factor not usually present in other methods of degradation, however, is the matter of rate of application of stress, as opposed to the level of stress. When a force is applied gradually, the stress is distributed evenly throughout the structure, so that breakage may be resisted or take place at a low level in a gradual manner, to leave a weaker area in the fabric that is not actually a physical break. If stress application takes place at very high speed, however, there is not time for the forces to be distributed, so that all the stress is borne by a single small area of fabric and catastrophic failure occurs virtually instantaneously. A large hole or rupture results, even though the force is only of the same magnitude that caused a relatively small weakening of the fabric in the low-speed application. Thus, rate of application of the source of potential harmful change is of much greater importance in the case of mechanical action than in that of other types of degradation.

10.8.2 Force application In considering the manner in which the forces are applied to textiles during production, it should first be noted that literally millions of fibres are being moved, often at very high speeds, by machinery that changes the position of the fibres relative to each other and to the surfaces with which they are in contact. Again, it is much more common to impose a variety of types of force, rather than merely a single one, on the fibres. During the opening of bales, tensile forces are used to separate individual fibres, but there is a certain amount of compression, bending, torsion or shear also implicit in the process as the opening device forces its way through the bale. Similarly, in carding, the card clothing that applies tensile force (as it removes clumps and dirt) also squashes, twists or bends the fibres as it passes through their grouped masses. Drawing by means of rollers teases out the fibre assembly into a finer strand, but does so only by squeezing the individual fibres against the rollers or against one another. The twisting action of spinning inevitably applies a torsional force to fibres while drawing them out against the surfaces of neighbouring fibres to reduce the cross-section of the strand.

10.9

Mechanical stress in manufacture

Even after the yarn is made, its individual fibres are still subjected to mechanical action. In weaving or knitting, the strand must pass through the small holes present in the healds or the needles, so that the outer fibres are compressed and abraded. The yarn is subsequently forced to move against adjacent yarns as the process continues, with the same effect on the outer fibres. In any winding operation, a yarn is bent, pulled and abraded as it is passed around or over guides, through rollers, or onto the cone or spindle on which it is being wound, so that the fibres are again subjected to various forces.

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10.10 Mechanical stress in use Mechanical action continues to occur after the fabric is manufactured. As cloth is pulled through various types of machinery for finishing, dyeing, printing or drying, tensile force is frequently applied to maintain the forward motion of the fabric. In other types of cloth transport mechanisms, rollers are used to carry the goods forwards, and frictional force (which automatically involves compression and at least some slight amount of abrasion) must be present for the motion to occur successfully. In cases where mechanical force is a necessary part of the cloth treatment process, such as in felting or some types of dyeing and printing, then compressive stress, often at high rates of application, will be experienced by the fibres. In a tenter, the drying operation is accomplished by drawing the fabric through the heated zone by means of a pin feed, so that small holes are made as the pins penetrate through the cloth. In this step, then, burst force is present at the same time as the fibres are subjected to the lateral tensile force that draws the material through the machine. Again, guide rollers are often an essential part of the dryer, applying compressive and abrasive actions to the surface fibres. At different stages in the fabric manufacture, too, there will be a variety of rolling or folding operations, all of which impart some type of mechanical stress to the cloth. The stresses imposed during manufacture, however, are more or less controlled and known. Usually, their magnitude is taken into account in setting up the process conditions. Calculations are carried out to ensure that the amount of force imposed is not sufficient to cause any significant damage to the material. The same cannot be assumed during use of the textile goods made from the fabric, since there is no means of controlling or, in many cases, even predicting the way in which external forces are applied to an article.

10.10.1

Apparel

An apparel item, for instance, is subjected to force every time it is used. As the body moves, the garments fitted to it will rub against the surface of the skin, or against another garment, or against an external surface (a chair or a wall, etc.), thus experiencing compressive and abrasive forces. As a garment is pulled off, it will be subjected to a tensile force until the resistance caused by frictional contact against some other part of the body is overcome. Compressive and abrasive actions will again occur at the same time, especially if the shape of the part of the body across which it is being pulled is of such a nature that impedance to movement is high. Contact with another surface can cause pilling, the phenomenon by which short fibre lengths are broken within the structure but in which the force applied is insufficient to pull the broken portions out of the yarn immediately. Zarens7 deals with the subject in some detail, describing pilling as taking place in three stages. The first of these is the formation of fluff, after which balls (the pills) are produced and, finally, detachment eventually occurs. Early discard speed and intensity are

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governed, he feels, by many factors and he discusses in outline the effects of fibre type, yarn construction, knitting or weaving parameters and finishes. Even the storage of clothing, on hangers or in drawers, needs the application of some force to get the article into place or to remove it in readiness for wearing.

10.10.2

Non-apparel uses

Commercial, industrial or sporting goods fabrics are notoriously prone to mechanical action. A tarpaulin or other covering material is blown about, often while in contact with sharp edges, so that tensile, compressive, torsional, shear, bending and abrasive forces are all being applied to it, at different times, as the cargo it covers is transported at speed on a road or rail vehicle. A conveyor belt is compressed at the region of reversal and abraded or compressed where it contacts the drive mechanism or, in a moving staircase application, by the feet of the people walking over it. Tents and sails are stressed constantly as the wind blows them, again with the potential for all the different modes of application of force to them. A rope used for climbing, or harness, or mooring purposes, will be under tensile stress, and may also be compressed or abraded against the surface of a dock or cliff or metal mooring ring. Cushions and curtains in the home, or in commercial space, are frequently in contact with a wall or a sofa or chair, and may be handled roughly by people moving them. Carpeting in the same location will endure the abrasion of shoe soles carrying particles of grit that increase the wear. Tyre cords on a vehicle are invariably subjected to high compression forces as the tyre bounces on the road and to tensile force as the rotational effect is imposed on them. Geotextiles are abraded by soil particles as rain washes over the fabric surface, or subjected to the stress of wave motion if they are in use as tidal barrages, or to the action of wind if they are part of a roofing system. Flags waving in the breeze are similarly abraded against the pole and pulled as air currents move them about.

10.11 Prediction of effects In many cases, efforts are made to predict the magnitude of the forces applied, in an attempt to design fabric properties to ensure satisfactory life. Cloth used for most purposes, for instance, is tested in laboratories to make sure that it will not fail when used or handled in a reasonable manner. Industrial, sporting and commercial fabrics are designed with a healthy margin of error to provide a reasonable life expectancy even under extreme conditions. Unfortunately, conditions of use are not always reasonable and testing cannot always be carried out in a way that will simulate every stress to which the cloth will be subjected. A rough child (or a badtempered adult) may subject a fabric to extreme forces that the manufacturer cannot reasonably assume will be present. A storm or high wind can impose on a material forces that cannot possibly be withstood, given its structure. Carpets or

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10.3 Effects of weathering time on
, tensile strength; ×, tear strength and +, abrasion resistance of nylon (source: ref. 8).

upholstery treated with the utmost disrespect will wear out far more rapidly than might be expected in a normal household situation. One major difficulty is the fact that inappropriate testing may be carried out. If, say, a rope needs to be tested, its resistance to tensile force is often measured. In use, though, the tensile mode may not be the critical one that is likely to cause failure. A nylon climbing rope, for example, will be subjected to high abrasive force at the edge of rough surfaces. Figure 10.38 indicates the possible unpleasant effect of assuming that a tensile test is adequate to predict rope safety. As is obvious from the graphs relating the change in resistance to tensile, tear and abrasive forces to the time of use, tensile failure is still unlikely to take place even after prolonged use, but resistance to abrasive failure, as a result of molecular changes brought about by exposure to the ultraviolet radiation in sunlight, is lost very quickly. Thus,

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the poor climber will plunge to his death because of the failure of a rope that could still appear to be satisfactory and safe by tensile stress measurement standards. The problem, of course, is an economic one. Higher quality goods are likely to withstand stresses better than inferior ones, but they cost more to produce. Manufacturers must therefore aim to provide their customers with goods of a quality that will give satisfactory service, for a reasonably lengthy period of time, at a reasonable cost. Dishonest manufacturers can disguise poor quality goods (e.g. by heavy raising of a fabric to hide a sleazy weave) but will not keep their customers long if a practice is made of this, and the conscientious manufacturer who eschews such fraudulent treatments will eventually outlast the cheating one. As long as the stresses imposed on the material are not excessive, an article of good quality will last in a manner that satisfies the customer. Indeed, in clothing, it is often a change in fashion that makes a garment redundant, rather than any mechanical failure. If a fabric does fail prematurely, though, there is the economic cost of replacing it, either for the manufacturer or, if the guarantee is not valid for the treatment it has received, for the consumer. In addition, no matter who pays financially for the loss, it is our long-suffering planet that once again has to deal with the extra environmental load when the article is thrown away before its intended date of disposal. Finally in this section we should recognise that isolated stresses are virtually unheard of, because a textile material is always simultaneously subjected to more than one type of degradative effect. Combinations of stresses should be considered next and, since there are so many potential permutations of the various effects present, it will be possible to select only a few representative samples of the more obvious ones to examine.

10.12 Degradative combinations It is relatively rare for any textile product to be exposed only to one single type of environmental challenge. Far more common is attack by two or even several different potentially degradative mechanisms at the same time. In practice, there is often a synergistic effect, where the combination of attack methods leads to a more rapid loss of properties than would be expected from a summation of the changes occurring in each case separately. As a result, it is usually impossible to allocate specific levels of the change taking place to any one type of attack and hence to predict exactly how a fabric will actually behave when it is put into service. All that can be done is to assume that the changes occurring will be at least the sum of those that would be expected from laboratory tests of individual types of environmental attack, and to design properties with a wide safety margin that, it is hoped, will allow the goods to function satisfactorily.

10.12.1

Maintenance

The most familiar common example of combination degradation, at least in terms

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of clothing, is regular maintenance. When a garment is dirty, it is washed or dry cleaned. In the former procedure, the textile is subjected to the action of water and chemicals in the form of detergent or fabric softener. At the same time, it undergoes mechanical stress as a result of the agitation given by the machine and, normally, a thermal loading. Afterwards, it is usually dried, either in a machine (with mechanical action and heat again) or in the open air, with exposure to ultraviolet radiation, movement as a consequence of wind and (on a really bad washing day) water and chemicals from acid rain. In dry cleaning, which is less severe on the textiles, only agitation and a chemical, the dry cleaning solvent, are involved, though elevated temperatures may occasionally be present.

10.12.2

Outdoor clothing

Clothing used outdoors in adverse conditions may suffer the consequences of enhanced attack. The simplest example of this is the existence of sweating during hard work, which brings about chemical or microbiological attack in conjunction with ultraviolet or water (possibly acidic) exposure. There is, too, an increased chance that mechanical degradation caused by abrasive force will also occur, since hard work frequently involves vigorous activity, such as climbing or fast movement. In such cases, less care of clothing is also common and contact with abrasive surfaces can be expected to result.

10.12.3

Weathering

Outdoor applications are also notoriously likely to subject other types of fabric to a range of mechanisms. Indeed, perhaps the most common and widespread of the possible cases of combinations of degradative mechanisms is the process of weathering. This will take place in any article that is used outdoors, whether as clothing, as industrial fabric or as sporting goods. Oxygen in the air and water in the form of solid snow, liquid rain or moisture vapour make contact with the material. So too do any chemical substances dissolved in the water, such as acidic material like carbon dioxide (also present as free gas) or, especially in industrial regions, components of acid rain. Together, these represent a combination of oxidation, water and chemical attack, but to them must be added ultraviolet degradation from sunlight. Sunlight (except on the above-mentioned bad laundry day) is always a potentially damaging agent and will add to the burden caused by the air and acid rain, subjecting the fabrics also to ultraviolet degradation. In addition, the textile may be subjected to mechanical stress if it abrades against a nearby surface. This may be a wall, the ground, trees, metal railings or any similar obstacle, but it may also be a human body or another textile product. These will add mechanical stress to the aqueous, ultraviolet and chemical ones already present. Textiles that will clearly be included in this category, apart from clothing,

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10.4 Effect of weathering on a nylon flag.

include tents, sails, tarpaulins, geotextile roofing or ground fabrics, flags or bunting, and garden plant protective materials, all of which inevitably involve outdoor exposure as a part of their useful existence. In addition, other marine uses (e.g. hammocks, sails and ropes) may also expose the textile fibres to salt water or to water that is contaminated with other chemicals. Figure 10.4 shows the flag that has been flying at the farm of the author’s daughter in Canada for only two years; the way in which it has been severely attacked and degraded in that relatively short period is clearly visible. Fabrics used in gardening applications will be especially likely to degrade rapidly, as a consequence of coming into contact with soilborne micro-organisms at the same time as abrasive, chemical and radiative contacts occur. Typical of this use is the grass-catcher bag attached to a lawn mower, or the fabric placed over tender plants as rainwater falls on them or wind blows across them. A piece of sacking used for this purpose is shown in Fig. 10.5 after outdoor exposure for about six months in the author’s garden, where it was used to protect tender plants against winter damage. There may also be some chemical attack arising from the presence of garden chemicals, such as fertilisers, weedkillers or insecticides, that enhances the risk of overall property loss when this type of degradative source is added to those already inherently present in the situation.

10.12.4

Indoor hazards

In indoor situations, multiple environmental hazards can also exist. Upholstery, curtains or carpeting in the home, at a workplace, or in a vehicle, are subjected to

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10.5 Effect of weathering on a jute garden fabric.

abrasion by contact with human beings, or by movement of furniture or drapery across the fabrics. At the same time, light falling on the textiles and liquids or fumes from sources inside the home (such as heating gas, cooking effluent, spilt foodstuffs and cleaning solvents or animal activities) likely to cause fading will add their contribution to the overall change in properties of the materials. It should also be remembered that the initial application of chemicals (such as dyes or finishes) to the materials may, in time, cause chemical attack to take place as a result of long-term changes in the substances used for such treatments; the same consideration holds true for many of the other examples provided in this chapter. Some fabrics, such as towels, tea towels or dishcloths, will inevitably suffer damage from abrasion as well as from the presence of water (and heat in many cases) during normal use, apart from that arising from their frequent laundering. Towels and bedding textiles will also be exposed to microbiological challenges as a result of their contact with the human body. Fabrics used in lamp shades are subjected to thermal stress as well as some of the ones already mentioned.

10.12.5

Tyre cords

A well-known instance of inevitable exposure to more than one type of degradative source occurs with tyre cords. These must be designed to withstand high temperatures during use at normal road speeds, as well as abrasion from movement of the wheels and should be resistant to burst tendencies arising during use, as a result of contact with nails or bouncing on uneven roads. In summer and winter

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conditions, they will undergo changes in dimension arising from expansion or contraction and must retain their adhesion to the tyre body despite this movement.

10.12.6

Other sources of degradation

More esoteric examples of degradation can be identified. A filter fabric may be exposed to chemical attack as well as mechanical force when it functions as part of a chemical process. Acoustic or thermal insulation material may come into contact with abrasive dust in the walls of a house (or even in the air itself), or with oil in the engine compartment of a vehicle. Protective clothing of the body from biological or chemical hazards, deep space exposure, deep sea diving hazards or merely from contact with oil or dirt, will suffer abrasion because of movement of the body at the same time as degradation from exposure to the element from which protection is sought. It should be noted particularly that virtually all of the examples given in this chapter involve normal operating conditions. The exposure of the textile goods to different types of attack is, indeed, expected as a result of the specific intended end use. This points up sharply the fact that environmental attack is a pervasive phenomenon, one that cannot often be avoided. It therefore becomes necessary to accept its existence and to try, as far as possible, to minimise its effect. This aim is demanding, and the ways in which attempts are made to accomplish it are the subject of the next chapter.

10.13 Magnitude of textile environmental damage contributions Before embarking on this survey, though, an effort will be made here to estimate just how large the actual problem of environmental damage related to textiles might be. We have seen how the production of fabrics or secondary products can be accompanied by ecological damage and how the industry tries to reduce the harmful effects as far as possible. We have also seen how degradative changes to textiles in manufacture or in use can lead to their premature discard, so that they contribute a further load on the environment that may merely be unsightly or may be toxic as well. How does this damage fit into the overall planetary harm we are causing as a species?

10.13.1

Assumptions

One way in which to estimate this parameter is to try to discover what place textile production and use take in the overall consumption of goods by humanity. In this approach, several assumptions will be made. The first is that the environmental harm caused by any process is directly proportional to the amount of product yielded by that process. Thus, if we double the production of a material in the second year of a two-year development stage, we will also double the ecological

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damage caused. This is not strictly true; the initial environmental costs of setting up the operation are not taken into account, nor is the fact that economies of scale can have an ecological, as well as economic, effect. Nevertheless, as will shortly be seen, the assumption is accurate enough for our purposes here. The second assumption is that the activities involved in making textiles are not the most highly damaging ones that humans can effect, nor are they the least damaging ones to the planet. The action of extracting metal ores from the Earth’s crust or that of launching a spacecraft, for example, will probably bring about much more profound changes (especially on an individual event basis) and lead to more environmental harm than does making a textile fibre or finished product. On the other hand, growing foods would be expected to be less damaging per unit of product than the manufacture of a textile article. The net effect of this assumption is that we need not make any special allowances (in the form of abnormally high weightings) in allocating an environmental harm figure to textile activities. The third assumption is that, if a product is made, it will be consumed or used and will contribute to ecological damage. Again, this may not be strictly accurate, because products may be kept in storage, but a large production base will render such exceptions relatively insignificant.

10.13.2

Statistics

With these three assumptions provisionally taken as valid, it is time to examine the facts. In the United Nations (UN) statistics for world production figures9 for the latest complete year available, 1999, it is possible to discover what quantities of a wide variety of products are actually made. Table 10.1 is a summation of what may be classed as raw material production, in which category fibres may be included. There is a discrepancy between the UN statistics and those reported in the textile literature, so the latter (larger) figure has been taken as the more accurate one to avoid biasing the conclusions drawn here favourably towards a reduced textile contribution to environmental harm. Even with this handicap, the textile contribution is minuscule, a mere 50 million tons out of almost 19 billion tons, or less than 0.3% of the total figure. Table 10.1

Annual production: raw materials (× 1000 tonnes)

Chemicals (organic) Coal and lignite Metal ores Petroleum and gas Non-metallic minerals Chemicals (inorganic) Fertilisers and agricultural chemicals Plastics and polymers Textile fibres Total

5000 431 4880 720 3777 868 3510 180 1014 344 382 487 217 971 105 977 50 872 18 940 850

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Table 10.2

Annual production: secondary materials (× 1000 tonnes)

Fuels Refined metals Non-metallic products Food Paper products Painting materials Wood products Hardware Textile products

3093 962 2166 451 2096 727 1521 504 503 423 53 485 36 455 22 557 10 114

Total

9504 678

Fibre production is not the only factor to be taken into account. Textile products must also be included in our calculations. Table 10.2 summarises the production figures for goods manufactured from raw materials. The secondary products of the textile industry, which can logically be included in this category, constitute an even lower proportion, 10 million tons out of over 9 billion tons, or just over 0.10% of the total. Finally, we must not forget that equipment used in making textile goods, or their end products, can have a large effect on the environment. In Tables 10.3 and 10.4, the annual 1999 production figures of heavy machinery and light equipment, respectively, are summarised. From the former table, it can be seen that textile production equipment, at 30 million tons in over 17 billion tons, is dwarfed by other machinery (agricultural, industrial and construction units, for instance) of comparable size to less than 0.2% of the total. Similarly, Table 10.4 shows that sewing machines are only responsible for some 0.05% of the total, or about 0.3% if very small items (notably writing instruments) are removed from the total to make a fairer size comparison. Thus, the average contribution of the textile industry and its products to world production figures is something like 0.25% of the global total. This estimate, of course, cannot be regarded as an accurate one. There are, for example, agricultural machines used for cultivating or harvesting cotton, and these are included in the agricultural category of the listing, not as textile machinery. In addition, the life expectancy of textile machines may be greater or less than that for other ones, leading to a higher or lower, respectively, effect on the planet per machine. Finally, the production of textile machinery appears to have declined markedly since the early 1980s, so the 1999 figure quoted may not accurately represent the current environmental impact of textile processing. Even allowing for this kind of error and even if the various other assumptions are faulty, however, the deduction that the entire textile industry represents a total of well below 1% of world commodity production figures is a very reasonable one to make. Thus, it is not fair to allocate more than about 1% of the world’s total environmental impact to the industry, a figure which is highly satisfying given the enormous contribution made by textile

Effects on textiles of natural exposure Table 10.3

Annual production: heavy machinery (number of units)

Agricultural machinery Industrial engines Construction and load-moving equipment Transportation machines Printing machinery Textile production machinery

11227 126 4776 276 994 252 237 092 672 666 31 526

Total

17 938 938

Table 10.4

Annual production: light equipment (thousands of units)

Writing instruments Small consumer goods Entertainment equipment Domestic appliances (large) (small) Metal and wood working machinery Office machines Sewing machines Musical instruments Electrical distribution Total

137

9540 651 1136 033 589 229 416 304 114 462 39 251 23 560 6805 4651 745 11 871 691

goods (and summarised at appropriate places elsewhere in this book) both to human survival or comfort and to environmental protection. So we can continue to use textile products with reasonable certainty that we are harming our planet far less than is the case with the application of other consumer goods. The best means of minimising adverse planetary effects, though, is to be careful about how we handle materials, taking good care of products to avoid any premature need to discard them and so cause pollution. This is to some extent an idealistic view, though, because textiles are not always restricted to normal conditions of everyday use and are, indeed, often intended for applications in which stresses far greater than those discussed in this chapter are present. The most crucial factors relevant to textile exposure, but not normally encountered under natural conditions of use, will be considered in the next two chapters. These are, respectively, devoted to the effects of high levels of heat and to chemical or microbiological agents.

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References 1 Chrobaczek, H., Dirschl, F. and Ludedrmann,S., Melliand Textilber., 1998, 80(3), 175– 177 and E 48–50. 2 Millington, K.S., J. Soc. Dyers Colourists, 2000, 9, 266–272. 3 Flammarion, G.C. and Danjon, A. (eds), Flammarion Book of Astronomy, New York, Simon and Schuster, 1964, p. 178. 4 Callister, W.D., Materials Science and Engineering, 5th edn, New York, Wiley, 2000, p. 21. 5 Rastogi, D., Sen, K. and Gulrajani, M., J. Soc. Dyers Colourists, 2001, 4, 193–198. 6 Oda, H., J. Soc. Dyers Colourists, 2001, 4, 204–208. 7 Zarens, D.Y., Geotextiles Mag., 1998, 53(12), 31–33. 8 Barnett, R.B. and Slater, K., J. Textile Inst., 1991, 82, 417. 9 United Nations, Industrial Commodity Statistics Yearbook, New York, 1999.

11 Thermal exposure

The effects of heat on textile products merit a separate chapter, because they are so important in determining whether the material can be regarded as a durable one. Heat is so frequently encountered by fabrics that it is almost automatically considered as an integral part of the list of constraints imposed on a fibre product, no matter what the intended end use.

11.1

Intensity

The actual results of exposure to heat, however, are entirely dependent on the intensity of the thermal source to which the textile material is exposed. These heat sources can include hot air (heated by any of the conventional means, such as electricity, gas, steam pipes, etc.), infrared, microwave or ultrasonic devices. No matter which source is used, though, the effects on the textiles are similar. The differences between the sources are restricted to the way in which the energy reaches the fabric, and the efficiency of conversion to actual usable heat, not to the way in which the heat generated reacts with the material.

11.1.1 Exposure levels At the lowest level of exposure, no detectable thermally damaging effects can be observed. There must, though, be some molecular modifications occurring, since changes in the fabric do indeed take place, but they are generally regarded as being insignificant in comparison with other changes brought about by exposure to air, moisture or other agents. Heat energy, however, reaches the fabric, increasing the molecular movement, a change that implies the possible modification of some bonds. These are most likely to be in the side chains where, as mentioned earlier, small incident energy first affects the target. The tangible result that we do observe is the phenomenon of thermal insulation. A heat source on one side of the textile emits energy that does not penetrate instantly through the material, so that some of it must be retained within the fibrous structure. The degree of this retention is governed by the actual structure present. Zhang1 and Bajaj2 discuss in detail the 139

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phenomenon of heat retention in textile materials in their contributions to a book dealing with the development of the new so-called ‘smart’ textile products.

11.1.2 Insulation The arrangement of textile material may vary from very open to very closed. We speak of the degree of openness of a structure with reference to open- or closed-cell arrangements. The two are illustrated schematically in Fig. 11.1. In Fig. 11.1(a), it is obvious that there are many passages from one side of the fabric to the other. Thus, air heated on the upper side of the fabric can pass through to the lower side, the rate at which passage takes place being governed by the ease of movement of the air. A very open structure will provide less impedance to flow, so allowing air (and hence heat) to move through relatively rapidly, while a more closed structure will delay the passage more effectively. In the limit, when the structure is extremely close, we reach the point at which there are no passages left through the material, a situation equivalent to the closed-cell structure of Fig. 11.1(b). In this case, the air in a cell near the surface on the upper side of the fabric is heated by the source, but the air contained inside the cell is trapped there and cannot pass on its energy directly across the fabric by convection. Instead, it heats the cell wall, which in turn heats the air on the other side of the cell, so that the next cell also begins to heat up. This process continues until all the cells, from the upper side to the lower side, have been heated. The consequence is a temperature gradient from top to bottom that is much greater than was the case in the open-cell structure. Two results follow from this fact. The first is that the closed-cell structure produces a much better thermal insulator than the open-cell one. The second is that the energy concentration in the portion of the closed-cell structure near the heat source (which is still receiving energy throughout the slow heat transfer process) will quickly reach a high temperature, one that matches that of the heat source in due course. Thus, if the source temperature is high, the closed-cell structure will be at a much greater risk of suffering damage than the open-cell one if damage is a possible end result of the heating procedure. As the amount of heat energy reaching (or retained within) the fabric rises, the potential for damage occurring becomes larger. Perhaps the most familiar case where this risk occurs routinely in the textile industry is in the drying of fabrics. Drying can be used at many other stages in textile processing (notably after washing or scouring of fibres, or dyeing of fibres or yarns) and the factors included here also relate to those alternative places in the production line where drying is incorporated.

11.2

Static drying

Fabric drying can take place in a variety of ways. Historically (and even today in primitive societies) drying was accomplished merely by leaving the fabric exposed outdoors in sunlight. This technique has long been abandoned in Great Britain,

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11.1 Thermal insulation in open and closed cell structures. (a) Open-cell structure, (b) closed-cell structure.

though the possible advent of a balmy climate may tempt manufacturers to revert to it in an attempt to reduce pollution if global warming creates a desert of the entire northern hemisphere. In other societies, though, the loop or festoon dryer, the drum dryer and the stenter (or tenter) are normally preferred. In the first of these, cloth is hung from a rack in an enclosed room in which warm air is circulating and is left there until the drying process has been accomplished, an exactly comparable analogy to the drying taking place in front of a fire in homes of a bygone age. The drum dryer, as is implied by its name, uses a heated metal drum, around which the fabric is tightly passed, to remove the water. In a drying oven, where the textile material is exposed to high temperature, it is usual to arrange for the goods to be moving relative to the heat source, either by establishing an airflow around the fabric or (as in the stenter) by drawing the fabric through a heated region of the machine.

11.3

Stenters

11.3.1 Process details Modern efforts to reduce financial losses and ecological loading have led to research into more efficient dryers. This has focused mainly on the stenter, which

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is felt to have the most potential for savings to be achieved. In it, the fabric is stretched between pins or clips at either side of the machine and drawn through a box inside which hot air is being blown. If drying is carried out correctly, the only significant change is the fact that water is slowly evaporated from the surface of the fabric, reaching there by a wicking process from deep within the fibrous mass. As a fabric dries, the moisture evaporates from its surface, to be replaced by fresh supplies of water moving from the interior of the cloth, setting up an equilibrium condition as long as there is any water remaining in the material. In this (steadystate) region of the drying process, the cloth remains at a constant temperature, at a fixed interval below that of the air in contact with it. Once loose moisture has been consumed, then bound water from inside the fibre begins to be extracted, and the cloth temperature slowly rises because this water is more difficult to remove. The final stage, in which molecular water is removed from the actual fibre structure, can bring about damage to the cloth in the form of scorching, and a rise in temperature is observed in both air and cloth. The aim of the dryer operative is to ensure that the fabric emerges before this stage is reached, but after all the loose water has been removed. Ideally, the fabric should leave the stenter at its equilibrium regain moisture content to minimise the chance of scorching or cockling, resulting from over- or under-drying, respectively.

11.3.2 Drying equilibrium Figure 11.2 shows the situation at equilibrium during drying. The air surrounding the cloth (no matter how the air has been heated) has a temperature Ta, while the cloth is at a lower temperature, Tc. The latter temperature remains constant (the socalled wet-bulb temperature) as long as the moisture content at the surface remains constant, fed by the moisture moving to the heated surface from within the cooler depths of the fabric. As soon as the flow rate falls, depriving the surface of moisture, the same amount of heat energy is no longer required to evaporate the water. Thus, temperature increases and the formerly constant wet-bulb temperature curve changes to one in which the temperature is rising gradually (the so-called fallingrate region of the drying curve). In this region, some of the heat is actually absorbed by the fabric molecules, rather than by the water molecules, so that internal changes in the molecular structure of the textile begin to occur. If the evaporation continues to occur to the point at which all the moisture has been removed before exposure to the thermal source is discontinued, then the fabric temperature rises to that of the heated-air source, as indicated at the right-hand side of Fig. 11.2. The level of this temperature will determine the type of change that can now take place in the textile structure. Vallier3 outlines all methods of drying yarns, woven fabrics and non-wovens, comparing warm air with steam transfer in imparting heat to the material, with an examination of systems in which warm gas, warm metal and radiation (infrared or

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11.2 Temperature changes during fabric drying.

microwave) dryer types are used. Giessmann4 describes a high-speed jet dryer for coatings, listing the needs for successful operation as (a) enough fresh air to dilute solvents, (b) controlled recondensation to avoid drips that could mark the coating, (c) controlled air flow to avoid any change in coating conditions, such as coat thickness or strength and (d) a continuously adjustable heat supply to 225oC for better dryer control.

11.3.3 Environmental problems Each type of dryer system has its particular environmental problems, though many of them are shared in common by all of them. The obvious one universally relevant is the matter of energy use. The heat needed to dry the fabric is not entirely used for this purpose, because a considerable portion of it escapes to the surrounding air. Various attempts to reduce the waste are made; the temperature may be lowered and the fabric left in contact with the heated area for a longer period of time, for example, but the economics of reduced production speed and the inability to prevent heat loss over a long time period both mitigate against taking this ‘solution’ too far. In the stenter, division of the heated box into sections, each at a different temperature, is often used, though there is, of course, no means of accomplishing total isolation of any one area in view of the need for cloth to be allowed to travel between them via open slits. Cantrell5 reviews developments in dryer technology, noting that better control of temperature and relative humidity, the key to successful drying, occupies the attention of many manufacturers, together with an increased trend towards automation. Schwartze6 revives the idea of using superheated steam, first proposed over 40 years ago, to avoid the risk of all water being lost from the fabric. He notes

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that, at 130 to 150oC and a cloth travel rate of 1 to 1.5 m/s, high and reproducible drying rates can be achieved. The absence of total dryness would eliminate the objections of Hughs and Price,7 who find that cotton quality is significantly reduced if high-temperature drying on ‘dry’ (6% moisture content) cotton is carried out, but no ill effects are observed if the initial moisture content is fixed at 18% during the drying. Gogoi et al.8 working with silk, note that deterioration by heat is more rapid if light is present, so it follows that valuable silk articles (such as historic fabrics in museums) should be stored in an enclosed airtight space under controlled temperature conditions.

11.4

New equipment

New equipment also features prominently in literature. Rydergren9 describes a tumble dryer capable of measuring the moisture content actually in the cloth, not merely in the air, a need reported many years ago (and met) by the author and some of his students.10–12 Hartmann13,14 introduces a new stenter design, in which quality and output are both increased while energy consumption is reduced. The same benefits are claimed by an anonymous author15 with regard to a multilayer stenter, which also occupies less floor space and needs less supervision. Olsen16 suggests the use of a laser beam for yarn drying, noting that it is capable of heating any fibre type at very high speeds.

11.5

Problems

11.5.1 Emissions A further common problem is the fact that the heating may cause evolution of harmful agents (* A-2, A-3) (see Table 1.1 for an explanation of codes) to take place. If the fabric is not completely free of chemical reagents used in a previous stage, for instance, the effect of the heat may bring about some decomposition and toxic material may be emitted. One such example is the production of hydrochloric acid or a cyanide when drying of incompletely removed excess antistatic, flameretardant or softening compounds occurs.

11.5.2 Damage The fabric, too, may decompose if the temperature is too high. The familiar sight and smell of scorched cloth, well known in the above-mentioned bygone homes, is duplicated in industry when an operative uses the wrong heat setting or allows the fabric to travel through the tenter too slowly. The result is a costly one for the environment as well as for the manufacturer’s pocket, since all the steps undertaken up to that point, from production of the fibre, are totally wasted if the fabric has to be scrapped. Any attempt to prevent such loss, by only partially drying and

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allowing the fabric to emerge still wet, may backfire if the damp cloth begins to rot or to cockle as a result of the excess residual moisture. The most risky aspect of this type of problem occurs in heat-setting, where an extremely high temperature is used to ‘set’ or ‘cure’ a finish (notably a permanent press one) on the fabric. In such cases, the time of exposure to the intense heat is of the order of seconds, but underexposure may mean that the finish is not properly set and can wash out, while overexposure can bring about destruction of the finish as well as the cloth. The first indication that changes have occurred is the way in which the fabric becomes harsh to the touch. This brittleness, or denaturing, results from the removal of all or most of the natural moisture normally present in the textile structure. Clearly, if water has been removed, then bonds must have been broken. Some of these will be in the side chains, where substitutional changes have taken place, but others (especially at higher levels of exposure) may well represent side chains that have been broken off from the main chain. As this denaturing becomes more pronounced, the next observable change, one in which colour modification is visible, begins to take place. The initial symptom is usually a yellowing, on the assumption that a white fabric is the one originally under consideration. This may again represent a change in the structure within a side chain, where specific types of bond are either converted from double to single or vice-versa. The vibrational energy being absorbed is at a different frequency as a consequence, so that absorption in the visible region now takes place, as is evident by the changed appearance. Further increase in energy brings about still more evidence of destruction. The colour change will now begin to be much more noticeable, being orange, brown and black in turn as increased energy absorption brings about increased destruction of the molecular structure. At the same time, dimensional changes are commonly seen; the fabric shrinks, twists or distorts in a non-reversible manner. These changes represent an exceptionally high level of thermal exposure, with mainchain scission being at least partly responsible for them, and would obviously be the result of a major error in commercial drying. Similar changes can be seen, however, if domestic ironing or drying before an open fire is done without due care.

11.6

Novel approaches

It was partly in an effort to reduce or eliminate these damaging changes that novel techniques for fabric drying were introduced into the textile industry. When fabric drying brings about this much damage, it is not only the environmental harm of discarding the fabric (together with the work carried out, energy used and raw materials or chemicals wasted in all the previous stages of its production) that is of concern, but also the immense financial loss that has been incurred in all these stages. If some safer (i.e. less damaging) way to expose fabrics to thermal energy can be devised, then clearly the margin of error before destruction takes place will

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become much wider. The earliest heating procedures, using hot air circulating around the tenter, suffered from the fact that a change could not be made rapidly enough to correct the situation if excess heating was taking place. There is a distinct time lag after noticing a harmful situation (and operating the correction control) before the faster-moving fabric can emerge or the air flow shut-off valve can stop hot air from being present in close contact with the cloth. The earliest simple modification was to use gas or electric heat in close proximity to the cloth as the source of energy. In theory (but not always in practice) these sources can be reduced to a low level at a very fast rate, so minimising the damage brought about in an error situation. Unfortunately, both are relatively expensive sources of energy and tend to heat the air as well as the fabric, leaving a residual high temperature in the vicinity of the cloth that can cause damage as before. For this reason, radiant heating from an infrared source was the next type of energy exposure system tried. This is far superior, especially as the energy is only absorbed when contact with a tangible target (i.e. the fabric) occurs, not during passage through the air. Thus, the surrounding air remains at a relatively low temperature, so preventing cloth damage by exposure to it. Other types of energy sources for drying, investigated subsequently, include microwave and ultrasonic ones. These last mentioned sources are still, to a certain extent, at an experimental stage of investigation. They appear to be effective (in terms of minimising both cost and cloth damage), but some drawbacks are beginning to emerge. Ultrasonic energy is used elsewhere in the industry, as mentioned earlier, to shred fibre samples for analysis by X-ray spectroscopy, so there must be some potential for mechanical damage to occur if a high level of exposure (as may well be needed for satisfactory drying to take place) is adopted. There has also been the suggestion of some evidence to indicate that the mere presence of microwave radiation (in the vicinity of overhead high-voltage electrical power supply lines, for example) may adversely affect materials in the area, including those of which the human body is composed, so there is reason (but so far no factual evidence) to suspect that textile degradation may also occur as a side product of its use in the drying process.

11.7 Flammability Environmental factors become most noticeable in the most severe application of thermal energy. If the heat applied to certain textile materials is extremely high, they can ignite and burn. The flammability of a textile (on the assumption that no flame-retardant finish or other treatment has been applied to it) is determined in the main by its molecular structure. A fibre that contains large quantities of oxygen, in conjunction with the carbon commonly present, for instance, is in general more likely to ignite and to continue burning after the flame source has been removed than one in which there is little or no oxygen. A fibre in which there are flameretardant atoms (such as nitrogen, phosphorus or a halogen) inherently present in

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the structure is less likely to ignite than one in which they are absent. Smith17 summarises the information needed to judge the ability of a number of fibres to resist high temperatures by providing a table of properties of high-performance and high temperature-resistant fibres.

11.7.1 Effects There are many sources of information about flammability; indeed, it is a subject on which vast amounts of literature have been written. For the purpose of this book, it is thus pointless to recount all the details of its many aspects. There is, however, one area that needs to be brought to light, that of the connection between flammability and the environment. The waste involved, the toxic emissions and the environmental cost of treatments are all important factors in the contribution of thermal attack to ecological damage, while the lack of resistance of many textiles to heat also needs to be taken into account. In other words, flammability is one of the instances where there is a two-way relationship between textile products and the environment. Kearns18 reviews the topic of flammability, giving details of test methods and factors affecting the phenomenon, such as fibre content, fabric construction, oxygen accessibility, weight, dyes and finishes. Indushekar et al.19 investigate the development of finishing treatments that could impart resistance to flame, water and oil to fabrics for chemical warfare protective clothing, but do not give any information to determine how much environmental risk is associated with such treatments. Sicratt Powell20 reviews the use of phosphorus-based flameretardant reagents for textiles, without mention of any new compounds that resolve the difficulties. Flame-resistant treatments have been of major concern as a result of a number of fires that have taken their toll on the life of human beings, especially those in the very young or very old age ranges. These people are unable to react quickly to an emergency, so can be engulfed by fire before they have any chance to escape from or extinguish the flames. It is not usually the flame which is fatal, though, but the toxic gases present as a result of combustion. These gases include carbon monoxide and hydrogen cyanide, so it is hardly surprising that survival times in atmospheres surrounding a fire are not usually too long. There is also a grave risk that anybody in a burning building has to contend with large quantities of smoke, so that clear sight is not usually possible and escape is thus hampered. The shock, too, of being confronted by flames can bring about a heart attack or a bout of panic that can prevent escape from the fire. Cantrell21 and an author from a French organisation22 independently focus on aspects of the latest developments in treatment of home furnishings against fire, while Nakanishi and Hashimoto23 compare the effectiveness of compounds of nitrogen, phosphorus, sulphur, halogens and boron, the traditional materials used in this area, singly or in paired combinations. Figures 11.3 to 11.5 show how limiting oxygen index (LOI) and various stages of the drying progress are related.

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11.3 Correlation between TDOP and LOI for a cotton fabric (source: ref. 23).

11.4 Correlation between MDRP and LOI for a cotton fabric (source: ref. 23).

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11.5 Correlation between the difference (FP–TDOP) and LOI for a cotton fabric (source: ref. 23).

TDOP (thermal degradation onset point), MDRP (maximum degradation rate point) and the difference between TDOP and FP (flash point) are all crucial indicators of thermal changes and their interdependence with limiting oxygen index can readily be seen. An anonymous writer24 reports a flame-retardant process that reduces the formaldehyde emissions frequently observed in combustion products to 5 ppm, well below the maximum permissible standard of 20 ppm, with no change in fabric qualities.

11.7.2 Textile impact Flammability can have an enormous impact on textiles, since a flame can destroy a fibrous material completely. When ignition occurs, the molecules begin to undergo a major change, with total destruction of main-chain bonds taking place as combustion continues. Charring, the transformation of a whole piece of fabric into a twisted, black, shapeless lump that has lost all semblance of its original form, is succeeded by the disappearance of part or all of the textile, leaving behind a small mass of ash or a bead of molten residue. In short, flammability utterly destroys a fabric, rendering it totally useless and unfit for any attempt at recovery. Thus, the environment suffers, by having a burnt piece of rubbish discarded into it. In addition, the actual side effect of this burning is the production of substances harmful in themselves to the environment. Combustion of a textile can yield not

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only carbon dioxide (* A-1), the obvious product of the oxidation of carbon, but also a whole range of undesirable substances (* A-2), ranging from simple ones like carbon monoxide or sulphur compounds to more complex (and highly toxic) ones like cyanides or furans. These can bring about all kinds of secondary problems for the ecological health of the planet and the species in it.

11.7.3 Benefits and risks In a conference report Holme25 balances the benefits of flame-retardant textiles against their environmental risks. As noted by several speakers, flame retardation saves lives and several of the substances used to retard fire spread, such as oxides of aluminium and antimony, together with various organic compounds, supposedly cause no significant risks to humans. The suggestion is made of using life-cycle analysis, rating the environmental impact from 0 (no impact) to 90 (maximum impact). Application of this principle shows that most compounds are similar in rating. Concerns remain, however; there is some suspicion that the incineration of bromine-containing flame retardants may produce dioxins (* A-2), though no evidence has been obtained to confirm or refute this hypothesis as yet. A list of acceptable compounds and of ones needing further studies regarding exposure risks is provided. Barton26 reviews new studies in flame-retardant compounds, pointing out that their toxicity is often lower than had been predicted. She notes, though, that more studies are needed on compounds of antimony or molybdenum, organophosphorus compounds and chlorinated paraffins. She quotes a promising line of research involving intumescent materials, ones that char on ignition and can thus form a barrier against further flame spread. Lin et al.27 investigate the effectiveness of nine new boron flame-retardant compounds, finding the results of their study to be encouraging. They state that the flame retardancy is enhanced by increased amounts of boron, the addition of halogens to the boron compound and the presence of coordinated bonds between boron and phosphorus or nitrogen. The latter factor also enhances wash fastness of the finish. The effects of exposing textiles to thermal energy range from near-undetectable to the most severe ones, depending on the level of exposure. Though the natural thermal environment, in general, produces little harm in contrast to that brought about by shorter electromagnetic radiation, like light or ultraviolet exposure, we must not forget that, as a consequence of the presence of our species on the planet, higher-than-natural levels of heat are evident at many stages in the life of a textile. The augmented natural environment, changed by human activities, is one in which textile products are forced to exist and to suffer the degradation resulting from their interaction with it. Thermal degradation is indeed a tribulation of tremendous importance to the useful life of a textile material. The only other degradative sources even remotely comparable in their widespread applicability and effects are the chemical and microbiological ones. These will be considered in the next chapter.

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References 1 Zhang, X., ‘Heat-storage and thermo-regulated textiles and clothing’, in Tao, X. (ed), Smart Fibres, Fabrics and Clothing, Cambridge, Woodhead, 2001. 2 Bajaj, P., ‘Thermally sensitive materials’, in Tao, X. (ed), Smart Fibres, Fabrics and Clothing, Cambridge, Woodhead, 2001. 3 Vallier, P., Tinctoria, 1999, 96(3), 52–60. 4 Giessmann, H., Int. Dyer, 2001, 3, 26–27. 5 Cantrell, M., Int. Dyer, 1999, 184(4), 28–30. 6 Schwartze, J.P., Wool Res. Org. NZ Rep., 1998, R 215, 1–22. 7 Hughs, S.E. and Price, J., Proceedings 1998 Beltwide Cotton Conference, San Diego, USA, National Cotton Council of America, Jan 5–9, 1999, pp. 1637–1641. 8 Gogoi, S., Baruah, B. and Sarkar, C.R., Colourage, 1999, 46(2), 23–30. 9 Rydergren, S., Textile Tech. Int., 1998, 7(6), 5. 10 Crow, R.M., Gillespie, T. and Slater, K., J. Textile Inst., 1974, 65, 75–81 and 228–230. 11 Crow, R.M. and Slater, K., Textile Res. J., 1974, 44, 309–378. 12 Chakravarty, R.K. and Slater, K., J. Textile Inst., 1978, 69, 370–378. 13 Hartmann, W., Melliand Int., 1998, 3, 206–208. 14 Hartmann, W., Colourage, 1998, 45(7), 49–54. 15 Anon., Knitting Tech., 1998, 20(6), 262–263. 16 Olsen, D.E., High Perf. Textile, 1999, February, 6–7. 17 Smith, W.C., Textile World, 1998, 148(10), 53–64. 18 Kearns, C., Can. Apparel, 1998, 22(2), 22–23. 19 Indushekar, R., Abo-Shosha, M.H., El-Iayel, M.Z. and El-Alfy, E., Man-Made Textiles in India, 1998, 41/5, 208–216. 20 Sicratt Powell, C., Am. Dyestuff Rep., 1998, 87/9, 51–53. 21 Cantrell, M., Int. Dyer, 1998, 183(10), 17. 22 Filature de L’Avesnois, High Perf. Textiles, 1999, June, 3. 23 Nakanishi, S. and Hashimoto, T., Textile Res. J., 1998, 68, 807–813. 24 Anon., Textile Month, 1998, May, 48–49. 25 Holme, I., Int. Dyer, 2001, 1, 34–37. 26 Barton, J., Int. Dyer, 2000, 7, 16–20. 27 Lin, M., Zheng, L., Mao, Z. and Jiang, H., Can. Textile J., 2001, 1, 71–73.

12 Chemical and microbiological attack

Textile fabrics are often subjected to attack by chemical agents, during both production and use. The effect produced will depend on a range of factors, notably the type of fibre, the type of reagent, the temperature at which contact between the material and the reagent occurs and the concentration of the reagent.

12.1

Reagents

Reagents that can be expected to come into contact with textiles on a regular basis include acids, bases, salts, bleaching agents, other oxidising agents and organic materials such as solvents or more complex molecules. The effects to be expected range from undetectable ones, through colour change and change in handle or dimensions, to partial or complete destruction. Whether the effects are enough to warrant discarding the textile material, thus putting a load on the environment prematurely, depends almost entirely on the type of product involved. A slight change in property (such as a fading of colour or a roughening of the surface) may render unacceptable an evening dress, or one component of a two-piece set or a portion of a carpet faded differentially by light. The same degree of change, though, may not be regarded as critical in an everyday dress or in car upholstery. Even very noticeable changes in appearance, which would cause an everyday garment to be rejected for further use, may be tolerated in working clothing and would certainly not be of any importance whatsoever in an industrial application, such as a tarpaulin, conveyor belt or geotextile. Conversely, a small hole worn in a fabric may be accepted in working clothing, especially if it happened to be in some part of the body where its presence is not obvious, but such a flaw would be very objectionable in, say, protective clothing, because it would allow harmful substances to penetrate to the human skin and cause illness or injury. A small hole would also not be tolerated in a container bag, as it would allow the contents to leak out, or in a conveyor belt, where it could snag and lead to a catastrophic failure, or in a tarpaulin protecting delicate materials from adverse weather conditions. 152

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153

Fibre type

12.2.1 Protein fibres Thus, the undesirability of the presence of chemical substances, even though their contact with textiles may be inevitable, is dependent on the precise situation. The importance of fibre type should be considered first. In production, for example, acids are regularly used to treat wool in carbonising or scouring and, on occasion, in bleaching, dyeing or finishing. As long as the acid is in dilute form, there is virtually no harm done to the fibres, so the treatments are regarded as highly desirable and safe. In the case of alkalis, though, making the same assumption would be dangerous for a wool fabric. Alkalis are indeed used in the production of wool, as in alkaline scouring, bleaching (notably with hydrogen peroxide), fulling, dyeing or finishing. However, these treatments are always carried out with extreme caution because of the risk of damage. The same is true of bleaching agents, many of which are also harmful to wool. Chlorine bleaches are so damaging that they simply must not be used. Wool is very seldom bleached to a white shade (but is more usually left in a creamy white). Even less severe bleaching agents, such as permanganate or peroxide ones, are potentially able to lower the quality of wool, so must be used with caution. All of these comments, incidentally, are generally true for other hair fibres and silk as well as for wool, though silk is slightly less susceptible to some of the harmful reagent types and more so to others.

12.2.2 Cellulosic fibres The reverse situation generally holds for cellulosic fibres, such as cotton, linen or viscose. These are relatively immune to alkaline damage, but much more susceptible to harm from contact with acids. Alkaline treatment is used, for instance, to produce mercerised cotton; the sodium hydroxide is applied to the cotton at a very concentrated level (about 38%), yielding a stronger and more lustrous fibre. It is true that, if exposure is prolonged, the fibre can disintegrate, but the time needed for such a drastic change is quite lengthy and does not constitute a real drawback to successful operation of the mercerising step. Acids, though, are so damaging that it is not possible to use acid dyes on cotton without risking harm. Despite this sensitivity, however, acid treatments are sometimes used in special cases. Organdy, for example, is made by treating cotton (usually after dyeing with a colour that will help to resist acid damage) with sulphuric acid at relatively high concentrations to render the fabric partially transparent. The treatment, though, is carried out under split-second timing conditions, the acid is washed off immediately, and the fibre surface is treated with an alkali to ensure that all the remaining acid is neutralised to avoid any lasting continuing reaction.

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12.2.3 Synthetic fibres In the case of synthetic fibres, especially the true synthetic ones, a different set of conditions applies. Most of them are totally impervious to attack by acids, alkalis or bleaching agents. They can be left immersed in quite strong solutions of any of these liquids for prolonged periods of time and will suffer only minimal, if any, damage. On the other hand, some of them (notoriously the acetates) are highly susceptible to the action of certain solvents that leave natural, and many synthetic, fibres totally unharmed. The more robust synthetic materials, such as nylon, polyester or olefin fibres, indeed, are undamaged by any but the most severe treatments with unusual organic compounds. Exposure to the same classes of compounds also takes place during use, though in this case application of the degradative agent is often not deliberate. Acids potentially able to cause damage can include common household liquids, such as fruit juices, some wines and vinegar, all of which are usually spilt onto clothing only by accident. Acid rain, the ubiquitous by-product of our modern industrial civilisation, can reach clothing or outdoor sporting and industrial fabrics with little note taken of its presence, when fabrics used for tentage, boat sails, geotextile soil stabilisers or coverings for loads are used outdoors. Alkalis coming into contact with fabrics might include baking or washing soda, detergents and garden lime, all of which can easily be spilt accidentally to contaminate clothing, household linens, marquees or garden coverings. Bleaching agents, similarly, can be accidentally scattered when carrying out laundry tasks, or when maintaining a swimming pool, again providing a risk of damage to indoor or outdoor fabrics. Solvents that can come into contact with textile articles might include nail varnish (or its removers), paint thinners, stain removal fluids, tile cement or electronic component cleaning fluids. In the latter cases, there are more risks than the chance of dissolving the fibres, a risk that is relatively low, given the tolerance of most textile-forming molecules to solvent action. It is more likely in many cases that the fabric will suffer damage because of impurities in the solvent, which will bring about a deposit onto the surface of the textile in the form of a stain so difficult to remove that the article may well be discarded before its useful life is completed, again producing an adverse ecological load. In the same way, salts likely to be encountered by the fabric may include spilt table salt, sodium or calcium chloride used to melt ice in winter road conditions, garden fertilisers or salt spray on a beach. All of these constitute a risk to the textile, simply because, when the liquid in which they are dissolved dries up, they will again leave on a clothing, industrial or sports fabric unsightly stains that cannot easily be removed.

12.3

Planned attack

In many cases reagents of a similar type to all of the above may be applied

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deliberately to textiles under conditions of normal use. Regular laundering or dry cleaning cycles are necessary by our modern standards and will expose the fabrics to alkalis, bleaching agents or solvents. In industrial applications, the textile product may actually be intended for deliberate exposure to corrosive or otherwise harmful chemicals. Filtration fabrics, for instance, will inevitably be subjected to hot oil, acids and bases or to organic compounds. Even though the filter cloth is made from a fabric especially selected for its resistance to the liquid impinging on it, there is every possibility that degradation will eventually take place, so that the filter must be replaced in due course to avoid its potential failure and as a consequence destruction of the equipment in which it is a vital component. Textiles can also find application as industrial container linings, included to resist the destruction of the outer container by contact with the liquid contained. Doublebagging of corrosive materials (though usually in solid, rather than liquid, form) is a common practice in many agricultural or environmental situations. In transportation, goods may be wrapped in textiles to prevent contact with harmful liquids, such as acid rain or mud, and the packaging material must be resistant to these contaminants. Textile roofing fabrics and ground-level geotextiles, in the form of erosion or tidal flow control systems, are deliberately exposed to water in the form of rain, polluted effluent or saline solution. In all of these cases, the textile material forms a vital part of the system in which it is used. Its resistance against the chemicals to which it is exposed is the main reason why it is selected in the first place. Chemical damage, although undesirable, is ever-present and virtually inevitable. Dyestuffs can be affected by the reagent contacting the fabric, or the textile itself may undergo some change in colour, dimension or surface handle. More critical damage, up to and including total destruction, is often a result of chemical exposure but the textile material may also be used to provide protection against such damage to other, more valuable, surfaces which it is designed to cover for this purpose.

12.4

Microbiological attack

Microbiological agents with the potential ability to harm textiles, making them unusable, can be classified into two distinct types, those which are insects (or insect-related) in nature and those which are derived from spores, bacteria or similar minute entities. In general, damage caused by insects tends to be localised and that caused by spores tends to be diffuse.

12.4.1 Insects Of the insects, the most familiar are moths and carpet beetles. The clothes moth is a much smaller creature than the moths seen flying freely around outside the home, being only about half a centimetre in size, with a greyish-yellow or brown body and darker brown spots on the fore-wings. It lays eggs in dark places, as the larvae that

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hatch from them cannot tolerate exposure to sunlight. One convenient dark place is, of course, the inside of a storage area where textile garments are located. When the eggs hatch, the larvae eat enormous amounts and are easily able to digest wool. In general, it is the cystine or disulphide linkages that provide food for the larvae and, as these are eaten, the integrity of the wool structure is destroyed. As a result, the fibre disintegrates, with the resulting familiar holes that ruin the appearance of the article and render it unwearable. If necessary, though, the larvae will eat (but not always digest) other materials. Thus, in order to reach the supply of food represented by a tasty wool snack, the larvae will eat their way through other fibres in a blend, or through an outer layer that protects an inner (wool) one. The carpet beetle behaves in a similar manner. It is about twice the size of the clothes moth, distinctively coloured with black, red and white markings on its back and white scales on the underside. Once again, it is the larvae, hatching from eggs laid in floor cracks under the carpet, that actually eat the wool. The larvae are spindle-shaped, with tufts of stiff bristles along the sides and ends of their bodies, but are less fussy about their diet than are clothes moths. The carpet beetle larvae, in fact, will eat a wider range of materials of animal origin, including meat proteins from (say) spilt gravy, as well as keratin from the hair of other animals than sheep, such as domestic pets. The damage tends to be characterised by long slits, rather than round holes, as the beetle larvae follow the line of the threads in a carpet instead of simply eating their way through the material from one surface to the opposite one, as the clothes moth larvae do. Barton1 claims that carpets are the most critical area in which to apply mothproofing agents, since a colony of moths can form there easily and can subsequently spread to less accessible sites, such as closets or drawers. She notes that research is in progress on means of lowering environmental contamination by increasing fixation levels, improving containment of finish chemicals and reducing water use.

12.4.2 Moulds and fungi The second type of microbiological agent, classified together under the name of mould or fungus, is actually represented by a wide range of creatures. Schatz2 states that mould and mildew not only cause unpleasant odours, but can also leave stains on fabrics and bring about problems, such as discolouration, strength loss, reduced elasticity and tensile strength, which can shorten the life of the fabric, or lung problems such as allergies or diseases harmful to the user. He notes that washing is often unable to remove these defects and describes a finish that is effective and that is not incompatible with either human skin or the environment. He then demonstrates the importance of antimicrobial protection by giving a comparison between protected and unprotected fabrics. Fungi in general obtain their nutrient supply by direct absorption, rather than by oral consumption, in a process of assimilation aided by the secretion of enzymes excreted by the fungi. There are over 100 000 types of fungi, of which several

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hundred may be active in causing damage in textile goods. They spread either by airborne distribution, by transmission on the bodies of animals or by a creeping process from a parent mass. When attack by enzyme-assisted absorption occurs, food in the form of carbohydrates is usually sought and textile fibres (especially cellulosic ones) can act as a rich source of this nutrient. The remaining portion of the textile is a fragile residual mass of the destroyed molecules with the carbohydrate removed. It often has an unpleasant odour resulting from the end products of decomposition. The transfer process is also aided by moisture, so that decay is accelerated in damp conditions. Many fungi are present in the soil, a fact that explains why goods such as tents or other sporting equipment are prime candidates for the rotting produced. Other chemical substances, such as nitrogen, sulphur or phosphorus, may also be the target of a fungal search for food, so that other fibres, like wool, silk or even nylon, may also suffer damage from this form of attack.

12.4.3 Bacteria The final type of microbiological agent that can cause problems for textile goods is the bacterial one. Bacteria are again of a wide variety, though the number causing destruction of textiles is smaller than in the case of fungi. They occur in virtually all parts of the Earth, but especially (in the context of this book) in soil, in the human body and even in air or water. The problematic ones are capable of decomposing molecules into their constituent atoms, leaving behind virtually nothing tangible if the process of damage is allowed to continue unabated. This activity is the reason why very few textile samples are available from antiquity, or even from relatively recent times, and why textiles disappear totally after periods of time of immersion in the soil. The need of water for the survival of bacteria is illustrated by the fact that we do actually have a few representative textile samples from Ancient Egypt. The arid climate there and the fact that the fabrics have been buried away from light have allowed the materials to survive because bacterial growth has been inhibited under these dry and dark conditions. There are also textile grave goods from Scandinavian burials of the first few centuries that have survived to the present time, simply because they have been immersed in peat and the conditions produced by the peat (acidic, dark and moist) have prevented bacteria from growing and have preserved the wool samples virtually intact. Soil bacteria are not the only ones likely to damage textiles. The bacteria present in the human body, excreted in such host habitats as perspiration, urine or other secretions, are a ready source of microbiological agents that can bring about damage. Clothing can often be seen to disintegrate into holes in areas where excretions of this type have taken place. Tendering into a weak region is quite common in such places as the underarm or crotch portions of the body. Again, darkness and moisture, both of which are characteristic of these regions, allow bacteria to thrive and multiply there in the absence of any preservative conditions (such as the acidic content of peat soil that prevents wool from rotting, as just

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described), thus making them a significant source of harm for the cotton clothing worn over the area. Bacteria can also exist in food or drink. Normally, textile fabrics are not left in contact with foodstuffs for any length of time, but occasionally (as, for instance, when a cloth used to wipe up milk spills or to protect cheese from drying out is lost behind a sink or under a refrigerator) fabrics that are in contact with bacteria may be overlooked. A problem may also occur if a house is empty for some time and a piece of cloth has accidentally been left in contact with some kind of beverage; when the householders return, an unpleasant odour arising from a rotted cloth is likely to greet them at the door. However, the bacterial problem is slowly being overcome, thanks to new finishes being introduced into textile production (as described briefly in Chapter 7). An anonymous author3 introduces the topic of antimicrobial fabrics, with effective elimination of microbiological agents for the life of a garment, that can be used for underwear and socks. Ibrahim et al.4 introduce antibacterial activity into cellulose-containing fabrics in conjunction with an easy care finish and a range of treatments that then combine to make the fabrics rotproof as well as providing other desirable properties. Yang et al.5 carry out work intended to increase the durability of antibacterial treatments, examining four methods with fabrics of cotton, polyester, acrylic and other fibre types present in hosiery. All the agents they test use the controlled release mechanism, although they recognise that other methods (such as renewal by laundering and the bonding of cationic substances to fibres) also exist. They use two common bacteria, Staphylococcus aureus and E. coli, as challenges and assess the influence of various conditions of application on the effectiveness of their test substances. As shown in Fig. 12.1, increased concentrations of antibacterial agent above a critical level and different curing times have no effect on the bactericidal activity, and this activity remains potent for at least 50 launderings. There are, though, still drawbacks to be overcome. Mansfield6 discusses antimicrobial agents, noting that traditional ones are an environmental hazard. In modern agents there are three different types of operational mode: (a) those functioning by controlled release, (b) those in which regeneration by a chlorine bleach reactivates their effectiveness and (c) those forming a barrier. He notes that hydrophobic fibres, such as polypropylene, polyester and nylon, only need surface protection, while hydrophilic ones, such as cotton, rayon or lyocell, have to be protected in all regions of the textile where water can come into contact with the fibres. The requirements of a good antimicrobial agent include safety (i.e. low toxicity to people or the environment and a non-allergenic, non-irritant nature), compatibility (i.e. having no negative impact on textile properties or processing) and durability to multiple launderings. In addition to the destruction of bonds, there are also instances where bacterial or fungal action can bring about discolouration of the fabric. Even textile fibres that are immune to attack by microbiological agents, such as the synthetics, can suffer

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12.1 Bactericidal activity of cotton fabrics finished with 2% (a) and 4% (b) PHMB against S. aureus. The number of laundry cycles in each group (left to right) is 0, 1, 5, 10, 25 and 50, respectively (source: Textile Chemist and Colorist & American Dyestuff Reporter, Vol. 32, No 4, April 2000, pp 44–49; reprinted with permission from AATCC).

visual damage that makes them unacceptable. The usual cause of this is the death or decay of some of the microbiological agent on the cloth surface, leaving residual stains that cannot be removed by normal maintenance procedures. In such cases, laundering and dry cleaning are ineffective. The only possible means of solving the problem is by resorting to chemical treatment with a bleaching agent or an acid that can destroy the invasive entity, although even these are sometimes ineffective. When this is the case, there is no alternative but to discard the article, with the end result of an adverse ecological load. New work is abundant in trying to devise more environmentally friendly alternatives. Sun and Xu7 note that durable finishes for antibacterial activity without adverse effect on fabric properties are indeed available and explain8 antibacterial action in simple terms. Benisek9 reports on a conference devoted to the topic, extending also to combating fungi, static electricity and ultraviolet radiation. Vigo et al.10 suggest the use of various magnesium compounds with hydrogen peroxide as antibacterial agents and show various fibre types before and after treatment with antibacterial agents and laundering. Lin and Wong11 prefer to recommend quaternary ammonium compounds because they are non-toxic and not carcinogenic. Anonymous authors in two journals mention finishes effective against bacteria plus either fungi12 or static electricity,13 respectively. Lee et al.14

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report a finish using chitosan and fluoropolymers that makes fabrics resistant to blood, as well as bacteria. Another worker15 provides details of an unusual antibacterial treatment based on pure metallic silver dyed into nylon yarns. Toray Industries16 report a finish that can withstand industrial washing and is effective against many different types of bacteria. No matter which of the microbiological agents discussed above is responsible for attacking the textiles, the final result is the same. The fabric is made useless by weakening, by staining or by actually disintegrating into holes. The tendency for this to happen with insects is much lower than it used to be, thanks to the modern methods of approaching the problem already discussed, but the omnipresent nature of the smaller agents, mould, fungi and bacteria, make it difficult to guard against damage from these sources. Careful maintenance can help, but it is necessary to keep a continual watch for the presence of these harmful substances and to prevent them from thriving if textile preservation is required.

References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Barton, J., Int. Dyer, 2000, 9, 14–16. Schatz, K., Int. Dyer, 2001, 6, 17–19. Anon., Int. Dyer, 2001, 6, 28. Ibrahim, N.A., Abo-Shosha, M.H. and Gaffer, M.A., Colourage, 1998, 45(7), 13–19 and 30. Yang, Y., Corcoran, L., Vorlicek, K. and Li, S., Textile Chem. Colorist, 2000, 4, 44–49. Mansfield, R.G., Textile World, 2002, 152(2), 42–45. Sun, G. and Xu, X., Textile Chem. Colorist, 1999, 31(1), 21–24. Sun, G. and Xu, X., Textile Chem. Colorist, 1999, 31(5), 31–35. Benisek, L., Textile Month, 1998, December, 12–17. Vigo, T.C., Danna, G.F. and Goynes, W.R., Textile Chem. Colorist, 1999, 31(1), 29–33. Lin, M.Y. and Wong, W.W., J. China Textile Inst., 1999, 9(3), 285–294. Anon., Int. Dyer, 1999, 184(2), 36–38. Anon., Knitting Int., 1999, 106/1257, 46. Lee, S., Cho, J-S. and Cho, G., Textile Res. J., 1999, 69, 104–112. Anon., Med. Textile, 1999, March, 2. Toray Industries Inc., Med. Textile, 1999, January, 3–4.

13 Protection of, or by, textiles from environmental damage

13.1

Aspects

There are three aspects of protective practices that concern textiles. The first is the matter of protecting textile materials from degradation as a result of exposure to environmental hazards. The second concerns the use of textile materials to provide protection for people or objects against environmental hazards. The third involves the provision of protection, in the form of textile components, for the environment against hazards resulting from natural or human causes. All three are important, but differ in their manner of action, and all three need to be considered in this chapter. We have already seen how a wide range of environmental factors can bring about damage to textiles. Protection against these has to take place at all stages in the existence of the materials, from their initial harvesting to their final use. Storage and maintenance should not be forgotten in the list of stages to be included in any survey of the subject. Care to avoid damage from incorrect moisture balance, excess temperature fluctuations and chemical or microbiological hazards during storage is crucial for many fibre types, but especially for those of natural origin. In moist conditions, as mentioned elsewhere in this book, cotton, wool, silk, linen and various other less frequently used natural materials can suffer damage from exposure to mildew, mould or other microbiological hazards. They (and many synthetic materials) can also be degraded by exposure to ultraviolet radiation. Thus, if a textile product is to be stored for a long period of time (more than a few weeks, for example), it should be wrapped or located in such a manner that humidity cannot come into contact with the fibres. Moisture in the form of liquid water or in the gaseous phase (in very high humidity conditions, for instance) should be excluded completely. The more severe the moisture conditions, the less time should be allowed before storage in waterproof wrapping is achieved, and the more resistant a fibre type is to microbiological or chemical attack, the longer the delay that can be permitted before taking this precaution. 161

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On the other hand, a totally dry storage medium can bring about embrittlement over a period of time, so a reasonable amount of moisture should be present in the air that is in contact with the textiles. Ideally, the conditions should approximate those of standard temperature and moisture content, 21oC and 65% relative humidity, respectively. Under such conditions, storage for a prolonged period can be expected to produce little or no change in the material, as long as light is also excluded. Other harmful chemical agents, of the types summarised in the previous chapter dealing with chemical and microbiological attack, must also be prevented from coming into contact with the goods, or they may suffer damage.

13.2

Maintenance

In the need to maintain materials, there are steps that should be adopted for their protection. Care should be taken to avoid using incorrect reagents for specific fibre types. The obvious example of this is the need to avoid chlorine bleaching agents in connection with wool or silk, or in a dyed fabric that will not tolerate this reagent without loss of colour. High alkalinity in detergents can also bring about destruction of some fibres and decolourisation of certain types of dyestuff over a period of time. Other fibres (notably acetates) are very sensitive to specific solvents, such as acetone and chloroform, and can be destroyed rapidly even on brief contact with these substances. Thermal attack can create difficulties for heat-sensitive fibre types, so precautions need to be taken during drying or ironing of, say, nylon, polyester, olefin or other synthetic fibres.

13.3

Degradation during use

Although the storage and maintenance of textiles can influence to some extent the effect of the environment on their longevity, it is normally the degradation taking place during use that is the crucial consideration when considering protection of fabrics. There are, in general, two distinct methods of achieving such protection, the exclusion of the harmful material and the deflection or neutralisation of its effects. Typical examples of the former technique include coating of the fibres in some way. Waterproof or oil-resistant fibre or fabric coatings, for instance, are used to prevent staining of household goods such as table linens, carpets or furnishing fabrics if contact with a spilt foodstuff or some kind of contaminant (perspiration, hair cream, deodorants, etc.) present on a human body occurs. Fabrics intended for use in sensitive areas, where contact with microbiological agents can occur (in gardening or filtration applications, for example), are often covered with a plastic film or fibre coating to delay rotting. Surface friction can be reduced, where mechanical action is likely to bring about premature wear into holes, by the use of coatings of, say, polytetrafluoroethylene (PTFE) on fibres or cloth to provide low-abrasion contact. Resins may be placed on the surface of fibres to control shrinkage that could make the fabric ineffectual for its particular end use.

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Chemical treatments

Alternatively, a comparable degree of protection can be achieved by using chemical treatments that are absorbed into, or adsorbed onto, the fibres. Water-repellent or oil-resistant finishes can also prevent staining on household fabrics and often have a much less noticeable presence because they are not detected as easily by touch as a plastic coating. This second technique, for this and other reasons, is usually greatly preferred to the coating one, and is by far the more common of the two approaches. It is applicable, too, to other types of protection. Flame-resistant finishes are commonplace nowadays and are compulsory in many jurisdictions for specific end products, such as children’s nightwear, theatrical curtains or set decorative pieces, and wall coverings or upholstery in public buildings. Softening agents, to reduce wear by abrasive contact as well as to make a fabric more comfortable to the touch, are regularly applied to clothing or household materials. The same reagents, usually of the quaternary ammonium class, are also effective against static electricity discharge that can cause shock. Microbiological attack is prevented or drastically reduced by finishes to combat rot, mould or insects such as carpet beetles or moths. Chlorination treatments are used to prevent wool shrinkage which, as mentioned above, can make a fabric unusable.

13.5

Protection of humans

The second part of the topic of protection, that of using textile goods to reduce hazards to human beings, can overlap some aspects of the first one. People prefer to remain dry, for instance, so the means of providing the ability to keep a textile from rotting in water can be modified to keep human beings dry in a rainstorm. Again, coating or chemical finishing methods are both applicable in this aim. People do not like electric shocks or garments that stick to them as a result of static electricity generation or discharge, nor do they like the feel of harsh fabrics in contact with their skin, so the use of quaternary ammonium compounds as softeners to protect fabrics from abrasion may also provide comfort to the wearer of garments made from them by preventing electrical discharges or static cling. The same treatment on carpets or furnishing fabrics can reduce the chances of an accident if a shock causes somebody to drop a glass object or to suffer a heart attack. An anonymous author1 reviews protective garments, taking into consideration fibre types, safety needs, survival factors, weather-resistant or other specialised applications, health, medical, military and defence uses. Hilden2 reports a conference dedicated entirely to health, safety, operative protection and environmental technology.

13.5.1 Prehistoric protection Although the protective nature of specially designed clothing has become of paramount interest, we must not overlook the original uses of textiles by our

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prehistoric ancestors. These early humans covered themselves to prevent death or injury from the cold climate of ice ages, or from overexposure to the harmful ultraviolet radiation from the sun, once the hairy outer coating of the prehuman creatures had been lost. The coverings also reduced the risk of injury from abrasive contact with stones, trees, hard ground and other such hazards that they must have encountered at least as frequently (and probably even more often, given their roving pedestrian lifestyle) as do their modern descendants. Garments to reduce the effects of weapon thrusts would also be a contributory factor to success in battle, and hence to survival, in those distant days. Subsequently, at a later time in history, uniforms must have played a part in making sure that a friendly warrior did not accidentally wound or kill somebody on the same side as himself in mistake for an enemy. Even today, we continue to seek protection from the natural environment by using clothing to provide thermal insulation in a cold winter, or radiation protection in strong sunlight, or water resistance in a heavy storm.

13.5.2 Ultraviolet protection Auger and Nantel3 carry out a general review of the factors associated with ultraviolet exposure, discussing the risks involved with regard to skin cancer and the various types of the disease. Prevention and protective factors, measured with the aid of ultraviolet analysers, are considered in the fabric context. The authors note that construction, the presence of liquid moisture (which reduces protective ability) and colour (dark ones provide better protection than light ones) are all of crucial importance in establishing the overall protective ability of a fabric. Kaspar et al.4 compare the effectiveness of solar protective fabrics in laboratory tests and in use, finding that, for low values of SPF (solar protection factor), the level of practical protection is less than expected from the test results, but that at high SPF values the tests accurately predict field trial results. An author from Deutsche Telekom5 and De6 suggest that ultraviolet radiation should be given more attention as a harmful hazard. De mentions the consequences of excessive exposure, such as sunburn, skin burn damage, ageing and cancer, and emphasises the need for a correct choice of clothing to protect against the harmful rays. He also examines the effects of different fibre structures, weaving patterns, dye shades and finishes, providing definitions of various factors able to express ultraviolet protection properties quantitatively. Similar work is reported by Jedrzejewski et al.,7 who include the effects of construction, porosity, density, raw material composition, bleaching and delustring on ultraviolet absorption. One author8 carries out a series of tests and recommends that a knitted structure made from a blend of synthetic fibres with Lycra offers the best protection against solar radiation. Percival9 tests the effects of several factors, including colour and fibre content, but feels that there is a need for more research to take place before definitive conclusions can be drawn. One writer10 finds that warp-knitted blinds are able to screen up to 80% of the

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13.1 Effect of an ultraviolet-absorbent finish on absorption at different wavelengths (source: ref. 11).

sun’s radiation to aid in the preservation of eyesight from bright glare and of thermal comfort in a solar-heated indoor location. Rupp et al.11 present a detailed survey of the topic of solar protection by textiles, noting that special constructions, finishes and ultraviolet-absorbent fibres are all used in this application. Transmission varies with wavelength, fibre type and presence of dyestuffs; Fig. 13.1 indicates how a special finish can block the harmful UVB rays while allowing most of the beneficial UVA rays to pass through the fabric. An anonymous author12 reviews the development of ultraviolet-protective fabrics, and notes that three factors may be involved, the fibre type, the finish applied and the method of fabric construction (or any combination of the above). He reports new finishes capable of providing up to 90% reduction in ultraviolet radiation in the critical 400 to 200 nm wavelength region on any fibre type, with no toxicity, irritation or effects on desirable fabric properties such as handle or softness. He also mentions a fabric that can absorb in the infrared region as well as the ultraviolet, so is cooler to wear. Cantrell13 surveys the problem of increasing solar radiation and notes that fabric advances allow consumers to select from a range of materials for protective coverings or garments. One article14 points out that the performance of polyester as the best available apparel fibre for solar protection is confirmed by the level of sales of outdoor garments made from it. Algaba and Riva15 measure the ultraviolet-protective factor of textile

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fabrics in vitro by using a measurement of transmission through a screen (a fabric or chemical) with the aid of a spectrophotometer. Solar protection factor (SPF, defined as the ratio of the time taken for a patch of skin to develop erythema, or reddening, in comparison with and without protection) is corrected for the nature of the solar spectrum in comparison with instrumental characteristics and to compensate for the fact that not all portions of the spectrum are actually harmful. The authors then provide a table showing the expected consequences of various skin types on exposure to a range of ultraviolet index conditions. Djani et al.16 describe a quick and simple method for assessing the solar protection capacity of textiles, based on the use of radiometers to measure the transmittance of specimens in the UVB (280 to 315 nm) and UVA (315 to 400 nm) regions. They present a summary of the comparative abilities of various fabrics as protective agents, ranking their specimens (best to worst) in the order polyester, wool, polyamide, polyester/cotton and cotton. ASTM standards17 for sun-protective clothing are now under development for consistency in labelling purposes.

13.6

Modern developments

13.6.1 Protective clothing More modern developments currently provide most interest in the subject of protection of humans from harm as a result of exposure to environmentally dangerous agents. Fung18 deals with the topic of protective clothing for sports or industrial purposes in some detail and provides specific information on medical and military types of application. He deals with resistance to infection, adverse weather conditions and nuclear, chemical or biological agents. A survey of some of the latest work19 includes information on combined flame-retardant and ultraviolet-resistant fabrics, finding (as might be expected) that different types of cloth give different levels of protection. The requirements of protective clothing under new European Union regulations are listed in one paper,20 and Nieves21 suggests that the evolution of protective clothing may be driven by government regulations as well as by the market; he also feels that heat stress, comfort and barrier isolation are the most critical factors in any type of protection and examines the issue of disposable versus reusable garments. In modern times, chemical warfare must also not be forgotten as a hazard. Indushekar et al.22 give information regarding this topic, testing several fabrics designed to incorporate protection against flame, oil and water in addition. Finishes are suggested23 as a means of controlling dust mites to relieve asthma, though complete eradication is felt to be impossible. A word of caution is sounded by Kuhn and Paulus,24 who feel that there is a need for a simple but reliable indicator of the presence of harmful substances (including chemical agents) on textile materials, from fibre to finished fabric state (especially in connection with the ecolabelling scheme) and propose adopting luminescent bacteria for the purpose.

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13.6.2 Protective gloves Protective gloves have occupied the attention of various workers. Performance, comfort and wear factors are examined in one case,25 while another author26 presents standards for gloves designed against thermal risks of contact, convection or radiant heat and against the small or heavy splashes of molten metal encountered by welders. Bontemps27 suggests that the use of a core of long-staple fibres wrapped with short staple ones can give a very abrasion-resistant yarn especially suited to protective glove construction.

13.6.3 Surgical gowns Perhaps the most familiar use of protective clothing is that of the surgical gown which, at least in theory, prevents the surgeon from coming into contact with bacterial infections as he or she carries out surgery (and, incidentally, prevents bacterial transfer in the reverse direction). In practice, traditional surgical operating theatre gowns of cotton are only effective as barrier cloths for a limited period of time (about 20 minutes, according to some experts), although a laminated gown developed by the author some years ago,28 illustrated in Fig. 13.2, can increase the protective ability considerably. It includes a seamless, water-resistant but breathable front panel, wide under-arm spaces to improve perspiration mobility, knitted structures at collar and cuffs to eliminate abrasion there, and ventilation arrangements, by means of bellows effect airflow, in the rear of the garment. The design provides an additional advantage in that the gown’s ability to resist the transfer of liquid water spares surgeons (who often wear a plastic apron over the top of cotton operating theatre gowns) mental worry about their safety, as well as eliminating physical discomfort arising from splashes of blood, irrigation water or other fluids frequently released in operating procedures. With the current notoriety of such diseases as AIDS and Ebola fever, mental comfort is also enhanced by the improved protection offered by such gowns.

13.6.4 Protection against other risks Protective clothing against other potentially harmful or fatal risks can also be identified easily. Firemen wear suits made from heat-resistant fibres to safeguard them against burns as they fight conflagrations at close quarters. Dirat29 describes clothing used in the French air force to minimise heat stress and resist exposure to fire or ultraviolet radiation, because he feels that safety and comfort are both closely related to lowered stress levels. Torvi and Hadjisophocleous30 summarise research into protective clothing for firefighters, with particular reference to the matter of estimating useful life and developing test standards, two areas potentially critical in a fire situation. They also consider the part played by moisture transfer, heat stress, design criteria and chemical protective clothing, recommending future

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13.2 A surgical gown with improved effectiveness.

research directions in these topics. Halls31 summarises the work of the British Textile Technology Group (BTTG) in clothing against heat and flame and the use of sunblinds against both of these is also explored.32 Police officers don bullet-proof vests made from Kevlar or other energyabsorbing fibres when there is any risk of being shot. Spider silk is being recommended33 for use in antiballistic garments because of its high energy absorption capabilities, four times as great as the strongest synthetic fibre currently available. ISO safety standards34 are published for protective clothing against stabs by hand knives, listing requirements for design, penetration resistance, ergonomic, water permeability and maintenance factors. Another paper35 gives more details regarding protection against ballistic impact, including information on resistance to bomb fragments using a polyethylene cloth that can also be adapted for armouring cars or heavy-duty marine uses and is stronger than steel or aramid. Thomas36 provides information of a practical application of this type, and Bell37 describes garments that protect against knives, guns and hypodermic needles for use by police officers, while Squire and Gaspar38 provide details of current military protective clothing designed for environmental as well as attack hazards, including aspects that still need attention to enhance protection. Machinists put on tough overalls to protect themselves against flying pieces of metal, as discussed by Slater,39 while tree trimming experts use similar materials to cover their legs in case a chain saw slips. In a nuclear power station, operatives working close to the reactors are covered in impermeable layers of cloth or plastic so that radiation leaks cannot reach their skins. Agricultural workers clothe themselves in garments40 made from fabrics impervious to the toxic chemicals they

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frequently spray onto their crops; in all of these applications, moisture vapour escape to maintain comfort and heat balance is essential. Ko et al.41 describe the development of a textile that can detoxify pesticides on the surface of agricultural clothing but is still breathable and biodegradable. Detoxification is achieved by means of new functional polymeric materials and these authors examine their effectiveness and the durability of their activity. In a test experiment, methonyl and aldicarb are neutralised by a halamine grafted onto a polyester/cotton fabric and the ability to function is still present after 50 machine washings. In a paper designed to illustrate the extent of skin absorbent poisoning risks, Klasmeier et al.42 investigate the transfer of toxic agents from textiles to the skin. Clarke43 discusses trends in health and environmental regulations, stating that we need to reduce our exposure to dyes by (for example) enforcement of legislation, risk assessment, black listing defaulting companies, better use of ecolabelling and the banning of skin-sensitive dyes.

13.6.5 Space exploration Space exploration demands complete isolation from the environment to allow the astronaut to leave the protection of the spaceship and carry out a walk in the total void of space. Employees likely to be exposed to dangerous chemical or microbiological agents, in a laboratory or production plant, use protective clothing to prevent harm from coming to them. The advent of biological warfare has brought this kind of need to the forefront of our consciousness. Even the simple use of fabrics to prevent sunburn, discussed already, should not be forgotten in this category. Telephone repair staff are provided with garments and equipment designed to protect them against environmental hazards (such as foul weather) as well as against injury,

13.7

Non-clothing protective needs

Protection of human beings in industrial or other non-domestic situations by textile articles that are not clothing should also be considered. Filtration of solids or liquids is an essential part of some processes and may be the deciding factor in establishing whether specific premises can be occupied by humans. In a factory, removal of dust (a problem discussed in detail in Section 5.15.2 of Chapter 5) from the air by filtration allows people to breathe more comfortably and can prevent or lower the risk of lung diseases. Contamination of spaces or samples, in a testing facility or a surgical operating theatre, for instance, can occur if bacteria or impurities that can harm people or invalidate test results are recirculated in the ventilation system. Such an occurrence could produce the impression that danger levels might be greater than they actually are, so leading to an erroneous report on safety, and so on. Filter fabrics again reduce the possibility of this type of problem arising. Food processing plants depend on clean air to eliminate the chances of

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toxic or otherwise unpleasant products being packaged with foodstuffs, and efficient filtration is necessary to achieve this. In some cases, readings of important data can be distorted merely by the presence of dust in the atmosphere; examples include the detection of smoke particles in a simulated fire situation or the measurement of radioactive tracer detectors in medical equipment testing. Any motor operating in a dusty atmosphere needs to be fitted with a filter to eliminate the risk of fire from overheating by preventing the dust from causing damage to the motor.

13.7.1 Filtration Liquid filtration that is essential includes an application as simple as the oil in a vehicle. If microscopic particles of metal produced from wear on the engine are allowed to build up and circulate through the lubrication system, the car will quickly seize up and major repairs will be needed. A textile product (or, more commonly in modern vehicles, paper functioning as a kind of textile material) prevents this from happening by filtering out the impurities and allows the car to be driven for an appreciable length of time before the filter has to be replaced to avoid trouble. In food processing, filtration of liquid components to remove foreign particles that could be harmful is frequently carried out in, for instance, the dairy or soft drink industries. Water purification plants can be fitted with polymeric materials to act as primary filters or as a part of osmotic, transfer, barrier or exchange filter mechanisms.

13.7.2 Acoustic protection Another type of protection offered to humans is an acoustic one where textile barriers are used to reduce the sound pressure level to which people are exposed. Sound energy travels through space in the form of waves and this energy can be dissipated if the waves meet an impedance that is sufficiently resistant to their progress. Textiles are ideally suited to this purpose, because they contain many millions of tiny air pockets that can accept sound waves and allow the energy they contain to be reduced by contact with, and transfer to, the fibres enclosing them. The fibres, having such a small mass, are set into oscillation very easily. The energy of the acoustic wave is dissipated as it is used in forcing this movement to take place, thus reducing the amount that is transmitted through the fabric. Acoustic barriers of this type are used in such diverse places as inside the engine compartment of a vehicle, in buildings such as libraries, factories or churches, and in aircraft passenger cabins. There are two distinct modes of operation, one in which the barrier prevents sound from passing through to an adjacent location, the other in which the energy present within a specific room is reduced within that space, and the nature of the absorbent differs in the two cases. In the former one, heavy, thick fabrics with solid surfaces are more effective, while a loose fabric with

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plenty of air pockets (obtained when long, loosely twisted yarns are closely packed together) is preferred for the latter situation.

13.8

Protection for the environment

13.8.1 Landfill liners The final section of this chapter, perhaps the most interesting but least familiar in modern times, is the use of textiles to provide protection for the environment itself, a kind of ‘debt repayment’ for all the damage done during manufacture of fabrics. One of the current uses of this type of protection is that of a landfill liner. This device is of benefit both to the environment and to humans, because it prevents the leaching out of toxic substances, so that they do not contaminate the ground water, and also ensures that human beings are not poisoned by them. Desirable properties for such a barrier include long life, resistance to mechanical action or ultraviolet degradation and attack by chemical substances (especially corrosive agents or solvents) that might be present with the materials dumped on the waste site. In general, geotextiles are used for this purpose. The fabric will probably be some kind of plastic, although coated traditional textile materials are sometimes used. The vital property needed is extremely low liquid permeability which can best be achieved by using these types of construction. Two anonymous authors review the advantages and applications of geotextiles for a range of uses,44,45 while another paper46 recommends them for capping landfill sites because they save money and are easy to install. Andrews and Richardson47 discuss the design and construction of geosynthetic-reinforced lagoon caps, while Haegemann and Van Impe48 test the effectiveness of these materials in drainage systems. Reddy and Saichek49 evaluate the performance of a range of types by testing them in different soils and under different pressures, checking visual appearance, tensile strength and moisture vapour transmission, and find that (as can logically be expected, since surface area and hence abrasive contacts will increase) their protective ability decreases as particle size is reduced. Sawicki50 develops a model to predict the mechanical behaviour of a material embedded in soil, using it to explain changes in the geotextile material. Those used as clay liners may eventually fail, either in use (as mentioned by Stark et al.51) or even during installation.52

13.8.2 Soil stabilisation Another simple geotextile use is in soil stabilisation, when a fabric is laid on sloping ground to provide a foundation that retains soil in place, instead of allowing erosion to wash it away, until root structures can develop and provide a better, natural, more stable anchoring medium for the prevention of soil loss. For this application, one writer53 suggests that efforts should be made to commercialise

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the use of jute but, for long-term applications, this could be a mistake as resistance to microbiological action is essential and jute is not well preserved under moist conditions unless a protective (and toxic) agent is applied to it. The material should also be unaffected by ultraviolet radiation (since it may well be exposed to light in some places), and jute is again not satisfactory in this regard. It does, though, possess the useful attribute of having high liquid permeability, necessary to allow natural water flow to take place so that plant waterlogging does not occur. Terkelsen54 feels that there is a need to market the entire idea of geotextile use more widely, not only to civil engineers but also to contractors and their ultimate clients. Sutherland55 reviews the available information on this subject, while Hoga and Zeinert56 discuss factors involved, as do Di Pietro and Crampton.57 Fagan58 tests different types for their effectiveness in improving the protection factor, and other workers59 compare the properties of various different polymers. Ogbobe et al.60 present two biodegradable materials (little-known natural fibres, malvaceae and pendulucata) and study their effectiveness in comparison with polypropylene, finding them inferior but still acceptable. Again, failure can occur; Palmeira et al.61 carry out a simple analysis to predict how it might happen, while Helwany and Shih62 develop a test to measure creep and stress relaxation simultaneously, a procedure they regard as essential to a complete understanding of the behaviour patterns. Garg63 adapts the principle in using a geotextile as a reinforcement for earth in a retaining wall, and Sawicki64 carries out a creep analysis of such a situation. Lawson65 explains the criteria for all such uses, with a consideration of causes of success and failure.

13.8.3 Road reinforcement The same kind of material can also find applications in road construction. Gowtharaman66 discusses the wide range of uses of this type, including ports, dams, canals, reservoirs and irrigation channels as well as road reinforcement. Mandel67 provides an extensive list of a similar nature, adding to it railway construction and sea cliff or beach erosion control as well as the uses already mentioned. Botto68 feels that a geotextile repair for a road surface is far quicker than the traditional one, enabling the resumption of motorway traffic to take place much earlier. One geotextile with low stiffness and another with high stiffness, in combination, are recommended69 as an optimum way of absorbing stresses imposed by traffic. Another work70 reports experiences of geotextile use at the subgrade– subbase boundary of a road. Heying71 suggests geotextiles as a means of reinforcing historic brick streets to extend their life. Mandel72 proposes them as protection for waterproof sheeting in rapid tunnel construction. High-altitude testing (in connection with Andean mining operations,73 but useful in predicting road wear) indicates that they behave satisfactorily even under intense ultraviolet exposure, and exhibit good chemical resistance under these conditions too.

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13.8.4 Geotextile filters Geotextiles are also used as filters to permit leaching of drainage water to occur, without movement of soils. Mlynarek74 investigates the conditions under which successful operation can take place and presents guidelines to enable engineers to carry out satisfactory installation. McKeown and Nelson75 recommend a similar installation procedure, while Lawson76 discusses the best way to prevent damage during the process. Richardson and Johnson77 suggest the use of secondary geotextile cushions to protect the primary fabric from installation damage. Watson and John78 design a geotextile filter by simulating soil particle bridges on the surface of the material, while Lafleur79 tests seven non-woven needle-punched geotextiles with ten soils to develop new criteria for selection of an optimum material in specific circumstances.

13.8.5 Water control Another use which is rapidly becoming recognised is for water control as, for instance, in tidal barrages (floating cylinders, composed of a fabric casing filled with buoyant material, such as a plastic foam) that restrict the intensity of wave action as heavy tides approach a shore. They are effective in preventing shorelines from being washed away by tidal erosion, so protecting the land from gradual disappearance below the sea. Their most famous application is probably their use, to good purpose, in the attempt to preserve the wooden foundations on which the ancient houses of Venice were originally built and which are now disintegrating as a result of modern water pollution. They are also used in various harbours around the world, either for a similar purpose or to provide safe mooring conditions for vessels inside the harbour when storms are raging in the sea itself. Apart from the protection afforded to such vessels, the calming action avoids the need to clean up a polluted shore after a storm has strewn wreckage on the coastal fringes. Floating textile barriers can be used in the clean-up process necessitated by the all-too-frequent oil spills that have become a familiar problem in the modern industrial world. The mode of action of these barriers is two-fold; they may be used to restrict the movement of oil away from a limited area of containment or they may provide an absorbent sink that soaks up the oil preventing it from leaking away to pollute the surrounding waters more widely. Again, two distinct types of construction are preferred in these two respective cases. The containment feature will be achieved most effectively by using a tight, oil-proof and impermeable material, while the absorbent mode needs an open structure that readily allows oil to penetrate within it, thus easily reaching the internal fibres that can then soak it up. Storage and containment of other materials may be considered in this section. Steacy80 provides management with information on how polyethylene liners should be installed, while Skelly81 uses a geotextile for storage and containment of

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tannery waste to prevent any failure, in order to comply with environmental regulations. Another author82 gives details of PVC geotextile cores used for eight sedimentation tanks to withstand erosion from the methane and other toxic gases enclosed by them, noting that they also resist weathering satisfactorily. Control of the banks of a river, canal or other waterway can be achieved in a similar manner. Moran83 describes the way in which a river is returned to its original watercourse by the installation of a woven coir matting and how the vegetative cover is revived over a period of time. Elias84 uses geotextiles to reinforce the soil in building a port container terminal and Duensing85 proposes them as liners for decorative water features.

13.9

Desirable properties

13.9.1 Incorporation The ways in which the desirable properties can be incorporated into textile materials for all the various needs described in this chapter may be classified simply into three modes. The first of these is the actual manufacturing conditions by which the textile goods are made. Permeability to air, moisture (vapour and liquid) and heat is enhanced by open, looser structures, while impermeability is increased by tight twist, close spacing of yarns, thick layers and polymeric coatings. Strength (and hence resistance to destruction by mechanical action) is achieved by using stronger fibre types, higher twist, thicker yarns and tighter weaving. Resistance to water or other liquids is enhanced by using hydrophobic fibres, tight twist, close spacing of yarns, a plastic or a surface coating. Resistance to ultraviolet radiation, microbiological agents, staining or flammability can be achieved by using finishing treatments.

13.9.2 Manufacturing criteria Second, the matching of manufacturing conditions to actual modes of end-use operation is a crucial factor in improving the effectiveness of a textile product. If the conditions of use can be predicted accurately, then precautions can be taken to ensure that the necessary treatment to counteract these conditions can be built into the fabrics initially. Strunga86 stresses the importance of selecting criteria carefully for every geotextile application.

13.9.3 Maintenance Finally, the maintenance procedures needed to keep the textile product operating at its optimum level should be followed carefully. In the simplest instance, laundering or dry cleaning recommendations should be followed, storage to avoid attack by, for example, moths, should be arranged, and care should be taken not to

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expose the fabric to sharp objects or harmful materials that can reduce its effectiveness in, say, protection against a dangerous gas or liquid. If these obvious precautions are observed, there is no inherent reason why the material should not continue to give satisfactory service throughout its designated lifespan. One clear drawback in this otherwise ideal situation is that there are dilemmas to be faced in the choice of conditions, either of manufacture or of use, since the needs of one set of desirable attributes may be diametrically opposed to those of another. If, for example, an impermeable and waterproof fabric is needed for a protective garment, then the way in which it is made will not allow it to be thermally comfortable. The person wearing it may well be protected from the harmful agent to which he or she is exposed, but will be so hot from perspiration that he or she will not be able to function effectively while it is being worn. In the same way, a fabric intended for use as an acoustic absorbent, made from loosely twisted fibres and an open structure, will tend to be weak, and so may not be able to withstand the stresses placed on it when it is mounted in position under tension, or is blown about in a windy setting. A finish intended to impart flame resistance may not be compatible with one that renders the fabric stain or ultraviolet resistant, so a curtain may not be able to resist fire and staining at the same time. There are many of these potentially incompatible situations. All that can be done is to accept the need to compromise, selecting the optimum set of conditions to achieve the most critical criteria without ignoring completely the ones of lower importance. In this way, the protection needed or imparted by a textile material can be optimised to ensure the maximum possible lifespan for effective operation.

References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Anon., Can. Textile J., 2000, 1, 22–25. Hilden, J., Int. Textile Bull., 2001, September, 74–78. Auger, C. and Nantel, R., Can. Textile J., 2001, 1, 66–67. Kaspar, K., Altmeyer, P. and Hoffmann, K., Melliand Textilber., 1998, 80(6), 536–539. Deutsche Telekom, Textiles Usages Techniques, 1998, 29, 34–36. De, P., Man-Made Textiles in India, 1998, 41(10), 435–439. Jedrzejewski, W., Kasturiya, N., Pandye, S. and Hensra, J., Przeg. Wlok., 1998, 11, 17– 20. Anon., Wool Record, 1999, 158/3655, 67. Percival, T., Colourage, 1998, 45(annual), 71–73. Anon., Melliand Textilber., 2001, 7(September), 221. Rupp, J., Böhringer, A., Yonenaga, A. and Hilden, J., Int. Textile Bull., 2001, November, 8–20. Anon., Int. Dyer, 2000, 3, 31–32. Cantrell, M., Textile Month, 2000, February, 36–38. Anon., Textile Horizons, 2000, September–October, 6. Algaba, I. and Riva, A., J. Soc. Dyers Colourists, 2002, 2, 52–58. Djani, M., Djani, M., Rosinskaya, C., Kizil, Z. and Weinberg, A., Melliand Int., 2001, June, 144–146.

176 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61

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Anon., Can. Apparel, 2000, 24(6), 12. Fung, W., Coated and Laminated Fabrics, Cambridge, Woodhead, 2002. Anon., Asian Textile J., 1998, 7(10), 41–42. Anon., Bekleidung Wear, 1998, 50(18), 14–16. Nieves, L., Nonwovens Ind., 1998, 29(8), 24–29. Indushekar, R., Kasturiya, N., Pandye, S. and Henraj, Man-Made Textiles in India, 1998, 41(5), 208–216. Anon., Int. Dyer, 1999, 184(2), 38–39. Kuhn, D. and Paulus, J., Melliand Textilber., 1998, 79(7–8), 550–551 and E 154. Anon., Textiles Usages Techniques, 1998, 29, 38–40. Anon., Textiles Usages Techniques, 1999, 31, 115–118. Bontemps, M., High. Perf. Textiles, 1999, May, 2. Slater, K., Can. Textile J., 1998, July/August, 16–18. Dirat, K., Textiles Usages Techniques, 1999, 32, 47–67. Torvi, D.A. and Hadjisophocleous, G.V., Fire Tech., 1999, 35/2, 111–130. Halls, R., Apparel Int., 1998, 29(8), 28–30. Institut Textile de France, Textiles Usages Techniques, 1998, 29, 17–20. Anon., Textile Month, 1999, January, 27. ISO Bulletin, 1998, 29(10), 14. Anon., Revista Technol. Tessila, 1998, 7, 144–145. Thomas, H.L., High. Perf. Textile, 1999, March, 7–8. Bell, J., High. Perf. Textile, 1998, November, 6. Squire, J. and Gaspar, N., Textile Asia, 1998, 29(10), 51–54. Slater, K., Int. J. Clothing Sci. Tech., 1998, 10(6), 75–76. Slater, K., Int. J. Clothing Sci. Tech., 1998, 10(6), 74–75. Ko, L.L., Shibamoto, T. and Sun, G., Textile Chem. Colorist, 2000, 2, 34–38. Klasmeier, J., Muhlebach, A. and McLachlan, M.S., Chemosphere, 1999, 31(1), 97–108. Clarke, E., J. Soc. Dyers Colourists, 1998, 114(12), 348–350. Anon., Allgemeiner Vliesstoff Rep., 1998, 26(3), 40–43. Anon., Asian Textile J., 1998, 7(11), 93–95. Naue Fasertechnik GmbH, Tech. Textile Int., 1998, 7(6), 9. Andrews, D.B. and Richardson, G.N., Geotech. Fabrics Rep., 1999, 17(3), 21–26 and 17(4), 14–19. Haegemann, W. and Van Impe, W.F., Geosynthetic Int., 1999, 6(1), 41–51. Reddy, K.R. and Saichek, R.E., Geosynthetic Int., 1998, 5(3), 287–307. Sawicki, A., Geosynthetic Int., 1998, 5(3), 327–345. Stark, T.D., Arellano, D. and Evans, W.D., Geosynthetic Int., 1998, 5(5), 491–520. Fox, P.T., Triplett, E.J., Kim, R.H. and Olsta, J.T., Geosynthetic Int., 1998, 5(5), 491– 520. Anon., Textile Dyer Printer, 1998, 31(12), 8. Terkelsen, F., Tech. Textile Int., 1998, 7(9), 15–19. Sutherland, R.A., Land Degradation Develop., 1998, 9(6), 465–511. Hoga, F. and Zeinert, W., Geotech. Fabrics Rep., 1998, 16(7), 40–42. Di Pietro, P. and Crampton, W.F., Geotech. Fabrics Rep., 1998, 16(7), 30–33. Fagan, Y., Textiles Usages Techniques, 1999, 12, 28–32. Kusumgar, Y.K. and Talukidar, M.K., Synthetic Fibres, 1999, 28(1), 5–11. Ogbobe, O., Essien, K.S. and Adebayo, A., Geosynthetics Int., 1998, 5(5), 545–553. Palmeira, E.M., Pereira J.H.F. and Da Silva, A.R.L., Geotextiles and Geomembranes, 1998, 16(5), 273–292.

Protection of textiles from environmental damage 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

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Helwany, S.M.B. and Shih, S., Geosynthetics Int., 1995, 5(4), 425–434. Garg, K.G., Geotextiles and Geomembranes, 1998, 16(3), 135–149. Sawicki, A., Geotextiles and Geomembranes, 1999, 17(1), 51–65. Lawson, C., Geotech. Fabrics Rep., 1998, 16(6), 26–29. Gowtharaman, S., Chem Eng. World, 1998, 33(2), 47–53. Mandel, J.N., Man-Made Textiles in India, 1998, 41(7), 308–311. Botto, F., Textiles Usages Techniques, 1998, 29, 66–68. Anon., High. Perf. Textiles, 1998, December, 7–8. Alobaidi, I. and Hoare, D.J., Geosynthetics Int., 1998, 5(6), 619–636. Heying, E.L., Geotech. Fabrics Rep., 1998, 16(7), 26–29. Mandel, J.N., Man-Made Textiles in India, 1999, 42(6), 227–230. Grubb, D.G., Diesing, W.E. and Cheng, S.J.C., Geosynthetics Int., 1999, 6(2), 119–144. Mlynarek, J., Geotech. Fabrics Rep., 1998, 16(8), 30–35 and 1999, 17(2), 24–27. McKeown, B. and Nelson, S., Geotech. Fabrics Rep., 1999, 17(1), 36–39. Lawson, C., Geotech. Fabrics Rep., 1999, 17(1), 32–35. Richardson, G.N. and Johnson, S., Geotech. Fabrics Rep., 1998, 16(8), 44–49. Watson, P.D.J. and John, N.W.M., Geotextiles and Geomembranes, 1999, 17(5–6), 265– 280. Lafleur, J., Geotextiles and Geomembranes, 1999, 17(5–6), 299–312. Steacy, A., Geotech. Fabrics Rep., 1998, 16(8), 36–39. Skelly, D., Geotech. Fabrics Rep., 1999, 17(2), 48–49. Anon., Ind. Textile, 1999, 25, 4. Moran, B., Geotech. Fabrics Rep., 1999, 17(2), 28–30. Elias, J.-M., Geotech. Fabrics Rep., 1998, 16(8), 50–51. Duensing, D., Geotech. Fabrics Rep., 1998, 16(8), 40–43. Strunga, V., Ind. Textila, 1998, 40(4), 238–241.

14 Conclusions

The problem of environmental stress exists and will not go away by magic. The planet is seriously overloaded by human activities, partly because of overpopulation but mainly because a minor fraction of the population that occupies the earth (concentrated in the developed regions of the world) is consuming at a rate far in excess of what the planet can sustain. The sources of stress are of two types, depletion of resources and pollution. Critical resources include the air, water and land, plus minerals contained within the land. Pollution takes many forms, but can be classed (in terms of effects on human beings) essentially into five distinct types, pollution of the air, the water, the land and the visual environment, together with an auditory onslaught. In general, all human activities, even the act of breathing, are environmentally harmful. Breathing uses up oxygen and releases carbon dioxide, a greenhouse gas, into the air. With some six billion people involved at the time of writing, the amount of oxygen used and of carbon dioxide generated by the population is not inconsiderable. Beyond the simple act of existing at a rest state, everything we do results in resource depletion or pollution of some kind, more severe in its effect than mere breathing, so the net effect of our presence on the planet is a major one. All of our actions are harmful in some way, but most of the adverse changes result from industrial activity. Since the time of the Industrial Revolution, we have steadily and consistently increased our onslaught on ecological stability to the point that we have now reached a situation where, according to many experts, we are overloading the planet by a factor of four to six times its ability, by its inherent compensatory mechanisms, to recover from the damage. All industries contribute to the problem, but the textile sector is often allocated a high share of the blame. This accusation is unfair, first because the proportion of goods and equipment manufactured or used in textile production is less than 2% of the world’s total production figure, making it unreasonable to regard the environmental harm done by the industry as greater than this proportion. More importantly, the products of the textile industry are essential to human survival, unlike those of the vast majority of other industrial output, with the exception of food and housing. Our luxury goods are just that, luxuries. They do not enhance human survival prospects 178

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in the slightest and may, indeed, be sources of envy that can bring about harm to humans when they become the motive for increases in crime or terrorist attacks on Western nations thought (with good reason) to be consuming more than their fair share of the world’s resources. A country without textiles, though, leaves its population at the mercy of the elements and would need to depend heavily on trade to rectify this drawback. That country would therefore be susceptible to economic or inimical blackmail in times of scarcity or war. Hence, textile production tends to be ubiquitous, so the perception that it causes high pollution problems is shared by most of the Earth’s people, a fact that accounts for the high proportion of blame attached to the industry in allocating shares of the world’s environmental difficulties. Finally, the products of the textile industry are often used in combating the polluting activities of other industries, providing a valuable aid in the struggle to reduce ecological damage. Textile production should be also credited with this compensatory benefit. All of this does not mean to imply, though, that the textile industry is blameless in the matter of environmental harm. There are many cases where harmful activities are still taking place, although it has to be said that textile producers are frequently willing to try to reduce the load their actions have on planetary welfare. Damage can arise during fibre production, whether by the agricultural problems associated with the use of fertilisers, herbicides and insecticides, or by the extraction and conversion of oil for synthetic fibre manufacture, or by the heavy equipment needed in mining from the earth minerals used for raw inorganic fibre materials or for making manufacturing equipment. In yarn production, environmental effects include those caused by the chemicals used in washing, scouring, bleaching or carbonising, together with the emission of gases from drying apparatus or of fibrous fly from baling, opening and carding operations. To them must be added the residues of chemicals used to alleviate spinning difficulties and the presence of dust or noise in the later yarn production steps. Similar adverse results are found in fabric production, where chemical assists, fibre waste and noise are also evident. It is in the next stage of production, the fabric treatment processess, that most of the well-known polluting actions begin to be most noticeable. This is especially true of dyeing and printing, mainly because the evidence of the presence of pollution is highly visible in a waste water stream. The discarded products of colouration are, indeed, notoriously harmful, because of their toxic or carcinogenic nature. There are, however, many harmful emissions from such processes as shrink-proofing and bleaching, or finishes used to impart desirable properties (such as flame-resistant, water-resistant or easy-care ones) to fabrics. Since the effluent is not coloured by the waste products of these production operations, they often tend to be regarded as less important in the public mind. When textiles are used, their adverse effects are still to be discerned. Use may be normal or unusual, but will always have some influence on environmental conditions, whether favourable or adverse. One of the most prevalent, but least

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recognised, harmful effects lies in the premature discarding of fabrics, whether because they have failed before their anticipated date of doing so or because they no longer satisfy the requirements of their purchaser. Discarding for the latter reason may, for clothing, be at the whim of fashion, or as a result of growth that means a garment will no longer fit. In other cases, redecoration may produce a clash of colour in a carpet or furnishing fabric, or an appearance of shoddiness in an older article that is unacceptable. In technical or medical textiles, discard may be the result of inability to fulfil the original function, whether this involves a defect in a protective garment (such as a surgical gown or clothing intended to protect against thermal, space, chemical or biological hazards) or an article, such as a conveyor belt or tyre cord, that needs to have a flawless textile component to prevent mishap or mechanical failure. The storage and maintenance of textile products are also sources of ecological harm. Laundering and dry cleaning make use of undesirable chemicals, while storage in unsuitable conditions again leads to premature discard because an unacceptable product results. Thus, right from the earliest stages of production to the end of its useful life, a textile entity, whether of fibre, yarn, fabric or end product, is responsible for causing a range of ecologically harmful situations. Fortunately, the industry has begun to recognise this fact and has started to take steps to rectify the defects. There is a new spirit of commitment in evidence, although this is only especially recognisable at present in the developed regions of the world. Legislation is slowly being enacted to reduce the damage done by the industry (as well as by other industries) to a lower level. Unfortunately, this legislation is not yet satisfactory. It does not place severe enough restrictions on producers to reduce the damage to the point where it can be eliminated by natural processes, it does not apply penalties that provide a real deterrent and it is not enacted in situations where economic harm may result. Since economic harm is an inevitable result of ecological protection if we are to achieve a totally healthy planet, it is difficult to see how a rational and sane society can use this excuse to delay or prevent remedial legislation from coming into force. Even relatively minimal suggestions, like the Kyoto Accord, are not accepted by many people. The fact that these people are still in positions of power and authority is a sad commentary on our unwillingness to accept a lowering of our lifestyle for the sake of the planet’s survival. The author is firmly convinced that the textile industry is capable of meeting any challenge, environmental or otherwise, if given the impetus to do so. This capability has been demonstrated time and time again in the past; the only reason for any reluctance to introduce sweeping changes for the sake of the environment in the present or future is the need to meet competition. Any change takes money and it is unreasonable to expect any company to undertake a major reshuffling of production lines if the result will be bankruptcy because other companies are not undertaking the same changes. Only when legislation forces the changes to be taken by everybody does a fair situation exist; profits are then not squandered

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because of being undercut by a company reluctant to be environmentally responsible. Also, as long as transportation costs remain at their current relatively low level, the legislation would have to be international in scope so that imports cannot be used unfairly in cheap competition against an ecologically responsible company. Despite all these problems, the textile industry is still managing to reduce planetary stress brought about by production and use factors. Reduction of harmful emissions into air or water, elimination of highly toxic substances, recycling and attention to problems of noise, radiation and similar consequences of industrial activity, are all taking place. Management staff have gradually become aware that, far from costing them money, environmental protection by these and other steps can actually reduce losses, thus being financially as well as ecologically beneficial. Work has also been carried out to ensure that the harm done by textile goods is lowered. Chemical treatments ensure that the products last longer, give better satisfaction or service and can withstand severe conditions more extensively. The ability to provide protection for human beings exposed to unpleasant or dangerous conditions of climate, chemical, radiative or other harmful exposure should also not be forgotten. Textile goods are used to provide safe conditions of work in industrial or medical applications, as well as to replace body parts that are worn out, so that a human being can survive life-threatening situations. In addition, textile products have proved to be invaluable in protecting the planet itself against the polluting results of other industrial processes. Geotextiles are used to stabilise soils after vegetation has been removed by clear-cutting forests or overcultivation of agricultural sites. They find applications in isolating harmful chemicals to stop any leaching into water supplies. They control water courses, such as rivers or streams, and prevent erosion of shores along river, ocean or harbour sites. They prevent collapse of roads in times of heavy water flow. In the future, the industry can probably expect radical changes to be introduced, simply because the planetary load cannot continue to be so devastating if we wish to survive as a species. In order to exist as a viable part of society, textile production will have to be limited, with a lesser choice of products, especially of the kind that are particularly harmful to the environment. This will inevitably lead to an increase in price, because a manufacturer’s successful ability to produce goods compels him to use heavy, complex machinery, with high ecological costs, to manipulate the minute units from which all textiles are composed. If the machinery is used less, to cut down on environmental damage, the initial cost will have to be amortised over a smaller number of products, forcing an increase in price of the fewer ones that are produced. The direction to be taken by the industry, then, is one on which it has already embarked to some extent, although changes will need to be brought about at a much greater rate than is the case at present. The reduction of pollution will play a crucial role in planning operations and factories. This will necessitate cleaner processes, better maintenance and more attention to detail, together with more

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careful design of equipment, processes and conditions. Less desirable products, with fewer convenience features, may well result, and colour or ease of care selections may be more limited as a consequence. Social standards will be the controlling factor in determining how far we are prepared to abandon our hedonism for the sake of planetary welfare. Government leadership is essential if the industry is expected to convert its operations to more responsible styles. The textile industry, which led the Industrial Revolution, is perfectly capable of leading the ecological revolution, given a fair opportunity to do so. It can and will become much more environmentally responsible if government leadership allows it to survive while doing so. It is our choice whether we want to make personal sacrifices or to sacrifice our planet instead.

Appendix

Section 1 Cotton scouring with enzymes The addition of enzymes to enhance the effectiveness of scouring operations while minimising the environmental load, as mentioned in Chapter 5, occurs under conditions such as those specified by Li and Hardin.1 These include the use of a surfactant with mechanical agitation and require careful selection of the optimum enzyme for commercial success. Figure A.1 gives comparative data on the effects on wetting time of dosage and treatment time for various enzymes. Calafell et al.2 specify optimum temperature, pH and surfactant conditions to reduce the use of raw materials, pollution production and energy consumption, all important and desirable traits. Manian3 recommends fine tuning of the time and temperature of a scouring bath to give the optimum wetting and scouring conditions for removing products of enzymatic hydrolysis. Traore and Buschle-Diller4 scour cotton with enzymes instead of sodium hydroxide as an environmentally friendly step. They investigate several enzymes, alone or in combination, under different conditions, and include the effects of agitation as a variable. They then measure absorbency, whiteness, mechanical properties and the level of impurities remaining, obtaining optimum results with the best combination of enzymes, pectinase with lipase and cellulase. Agitation is not important, subsequent dyeing is uniform in all cases, whiteness is slightly enhanced and all trials yield a softer fabric except when cellulase is present. Sawada et al.5 propose bioscouring using pectinase enzyme with a multiple mixture of surfactants and D-limonene as assistants, for cotton scouring that is as good as, or better than, that resulting from the conventional alkaline scouring process. Figures A-2 and A-3 give an indication of the weight loss and changes in methylene blue value as a function of scouring time, with and without enzymes and surfactants. Subsequently, Sawada et al.6 express the belief that scouring in a nonaqueous medium using a pectinase enzyme has great potential. They find that enzyme activity is still excellent in the absence of water and that the results are equal to or better than those obtained in an alkaline scour. Figure A.4 provides a 183

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Appendix

A.1 Effect of enzyme dosage and treatment time for various enzymes on wetting time of knitted fabrics; owg = onweight of goods (source: Textile Chemist and Colorist, Vol 30, No 9, September 1998, pp 23–29; reprinted with permission from AATCC).

Appendix 185

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Appendix

A.2 Comparison of weight losses in conventional and enzymatic scouring of raw cotton; owf = onweight of fibres (source: JSDC 114 (1998), p 334. Reprinted with permission from the publisher, the Society of Dyers and Colourists, Bradford, UK).

A.3 Comparison of methylene blue values in conventional and enzymatic scouring of raw cotton. For key see Fig. A.2 (source: JSDC 114 (1998), p 334. Reprinted with permission from the publisher, the Society of Dyers and Colourists, Bradford, UK).

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A.4 Principles of operation of enzymatic scouring (source: JSDC 114 (1998), p 356. Reprinted with permission from the publisher, the Society of Dyers and Colourists, Bradford, UK).

schematic diagram illustrating the principle of operation of enzymatic scouring. Buschle-Diller et al.7 compare the scouring methods (sodium hydroxide, organic solvent and pectinase), finding that the first gives best whitening, the second highest tensile strength, and the third the softest yarns. They also note differences between open-end-spun and ring-spun yarns, concluding that yarn structure may have some effect. Figure A.5 allows a comparison to be made between the surface features induced by caustic, solvent and enzymatic scouring, while measurements of tensile strength given by the authors to justify their conclusions are illustrated in Fig. A.6. Etters et al.8 extend the above findings to some extent, because they find that alkaline pectinase gives a softer fibre, better water absorption, cleaner effluent and lower costs in the cotton preparation process overall.

Section 2 Wool scouring with enzymes The alkaline treatment of wool for cleaning purposes, also discussed briefly in Chapter 5, is described by a number of authors. Gacen and Cayuela9 bleach merino wool tops with hydrogen peroxide in acid and alkaline media at various concentrations of the peroxide, finding that the alkaline conditions produce wool that has better whiteness but is more easily attacked chemically. In recent years, the ability

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A.5 Effects of caustic, solvent and enzymatic scouring on scanning electron microscope (SEM) surface features of cotton fibres (source: ref. 7).

A.6 Tensile strength changes induced by various types of scouring of ring-spun and open-end-spun cotton yarns (source: ref. 7).

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of enzymes to improve this situation, by eliminating (or lowering the quantity of) the alkali needed has been noted. Heine et al.10 are in the process of testing whether enzymes can reduce the mechanical stability of vegetable matter, such as cellulose, pectin or lignin, to enable its removal to be accomplished merely by shaking, without damaging the wool or lowering dyeing quality. Other suggestions to improve the cleaning operation are reported. They include one by Neyers et al.11 to adapt complexing agents to compensate for the greying of wool by the presence of iron ions from contact with machinery. In a second one, Schafer et al.12 suggest different types of adsorbents (such as silica gel, diatomaceous earth, zeolite, alumina, Fuller’s earth, sodium carboxymethylcellulose and bentonite) for the removal of residual dirt. Kasztelnik13 compares the advantages and costs of solvent scouring of wool with the conventional alkaline one. Lennox-Kerr14 describes a new system of wool scouring with much lower water usage, based on partial liquefaction of contaminating greases, with their subsequent absorption and separation. An anonymous writer15 reports an environmentally sound scour in which there is total recycling of effluent, with no pretreatment; a heat exchange arrangement is used to evaporate liquid and the effluent itself is converted to a high-solid state by forced-circulation passes. Another writer16 reports a scouring process that can remove pesticides, as well as dirt and grease, from waste water, in a system without the need for halogen-containing compounds.

Section 3 Bleaching with peroxide Chapter 5 mentions the need to stabilise peroxide as a bleaching agent to enhance its effectiveness and this topic receives the attention of a few research workers. Chakrabarty et al.,17 working with knitted fabrics and noting that stabilisers can be used to improve peroxide bleaching of cotton, find that non-silicate ones are preferred to silicate ones because they yield a softer yarn with no adverse effect on dye uniformity. Sekar18 reviews developments in peroxide bleaching, noting that some fibre damage can occur with this reagent, and proposes the use of peracetic acid for bleaching cotton. Chattopadhyaya et al.19 agree, recommending substituting this reagent for conventional peroxide or hypochlorite ones, because it is so much more ecofriendly and favour the use of a non-silicate organic stabiliser once more. The net effect is improved whiteness, with less loss of tensile strength and abrasion resistance, accompanied by increased softness, but the product is still susceptible to photoyellowing on exposure to sunlight. Deo and Wasif20 suggest changes in the formulation to allow bleaching of polyester/cotton blends in a manner that can save steam, energy and water while being more ecofriendly and avoiding the production of toxic compounds from chlorine bleach decomposition. The advantages include lower consumption of chemicals, lower effluent load and hence a reduction in biological and chemical oxygen demand.

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Section 4 Sizing and desizing Work on sizing and desizing operations, introduced briefly in Chapter 6, is described by a number of authors. Sizing attracts the attention of Thomas,21 who focuses on the reduction or disposal of waste chemicals and provides lists of undesirable sizing materials. He also reviews important relevant topics, such as alternative sizing methods, yarn tension control, warp preparation and quality issues. Perkins22 describes the basic principles of the sizing and desizing stages, including details of recent innovations. Hyrenbach23 stresses that new demands on sizing for environmental constraints, new fibres and new spinning or weaving technologies mean that some evolution in the process of sizing is critical. Trauter et al.24 survey sizing work, including prewetting, pretreatments, chimgel sizing and expert systems that provide potential savings in size use, then recommend the use of starch/PVA (polyvinyl alcohol) blends of size. New compositions are reported by Vasil’eva et al.25 that enhance mechanical properties by combining the size with easy-care and shrink-resistant finishing to save energy and materials. Chen et al.26 assess the effects of CPI (corn-protein isolate) starch on the mechanical properties (size penetration, tensile strength, elongation and bending flexibility) of sized yarns critical to weavability, in comparison with those resulting from the use of commercial starch or PVA sizes. They show scanning electron microscope pictures of the way in which the three reagents penetrate into yarns and fibres. Penetration into yarns is virtually 100% for PVA and 27% for the commercial starch, but only about 17% for CPI. Nevertheless, because fibre penetration is higher for CPI than for the other two starches, the bending rigidity with the CPI (though less than that for the PVA-treated material) is greater than that achieved with the commercial starch. The authors find that their new formulation produces yarns that, in addition to being stiffer than those with starch (but comparable to PVA-treated ones), suffer less impairment of elongation than in the current treatment methods, with improved yarn surface properties. Frontczac-Wasiak et al.27 propose using casein grafted with ethyl acrylate as a size for rotor-spun cotton, wet-spun linen, silk and woollen yarns. This combination can be used without auxiliary agents and tests carried out before and after sizing indicate the strong possibility of its potential usefulness in commercial applications. When attention is turned to desizing, there are again some interesting papers in the literature. Jakob28 describes the process, giving a range of variables and some possible ways of improving its effectiveness. Patra and Chattopadhyay29 mention enzymatic desizing in an article dealing with the benefits of various treatments, including also pectin removal and silk degumming, with information on acidic, neutral and alkaline conditions for the elimination of cellulases. Nalankilli30 feels that the use of an enzyme for desizing is more effective and economical than using inorganic acids or alkalis, as well as being much safer. The article describes uses in defuzzing apparel knits, scouring cotton fabrics and biowashing denims. An anonymous author31 lists a range of new sizes, including some operating at

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low or high temperatures, with special mention of a subgroup for the vital (to today’s consumers) process of stone-washing jeans. Mention is also made of dyebath lubricants that prevent creasing and abrasion while lowering the need for washing off in cellulose reactive dyeing. In two papers, Jakob32,33 describes the advantages of oxidative removal of starch-based sizes, listing types of removal, such as peroxide or oxidative alkaline cracking, currently available. Kuo34 describes low-temperature plasma desizing for polyester and polyester/cotton blend fabrics, noting that the efficiency of the process depends on the gases selected as well as the pressure and power level used. Efficiency increases with pressure, but cloth quality diminishes if pressure is too high and removal is increased if the fabric is prewashed in a hot bath before the plasma treatment is carried out. Huang35 investigates the possibility of carrying out desizing, scouring and dyeing of cotton in one bath, and feels that his laboratory studies confirm the validity of this suggestion. The possibility of recycling sizes also receives some attention. Stegmaier et al.36 investigate the feasibility of such a beneficial environmental advantage, finding five acceptable formulations at the time of their enquiry. Brusa37 describes the technology of ultrafiltration necessary in the recycling operation, associating these needs with the desirable properties of the sizing agent and provides examples of sizes that he feels are suitable.

Section 5 Pollution reduction in dyeing The reduction of planetary loading in dyeing, as mentioned in Chapter 7, is attempted in a number of ways. Schramm and Jantschgi38 assess dye technologies from the viewpoint of their tendency to cause environmental damage, finding that the methods adopted at the time meet regulations but still leave a lot to be desired. Writers review a conference on the science and art of dyeing,39 new dyeing machines40,41 to reduce cost, energy use and environmental impact, dyeing carried out simultaneously with cross-linkage in finishing42 and novel means of applying traditional dyeing technology.43,44 Lomas45 points out that, despite all the new applications of science, colourfastness during laundering is still a major unresolved issue, as is fibre damage, as reported for wool dyeing by Naithani et al.46 Azo dyes, long regarded as stalwarts in the industry, have also been viewed with less favour in recent years. These versatile dyes, as noted by Yadav,47 constitute some 60 to 70% of the world dyestuff market, but contain carcinogenic components, typified by the four identified by an anonymous writer,48 who explains the German legislation relating to them. Singh and Parmar49 suggest that the harmful effects of azo dyes are so bad that a return to natural ones should be considered seriously and, after reflecting on their health, safety, yield and quality criteria, affirm the wisdom of such a step in spite of their admitted drawbacks. Ammen50,51 recommends a return to sulphur dyes, rejected in the past for their unpleasant odour, ecologically undesirable nature and unsafe components, because he feels that recent work has converted them into the best choice on both ecological and economic grounds.

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The use of plasma treatments, also mentioned in Chapter 7, is yet another method of approach to the thorny problems of environmental conservation in dyeing. Thomas et al.52 use scanning electron microscopy and X-ray spectrometry to examine the surfaces of wool, cotton, polypropylene and polyester to determine what changes have taken place there as a result of plasma exposure and also study the effects on dyeing properties. Hocker53 and Schafer54 propose using ultrasound as a dyeing assist, with Schafer noting that evenness and diffusion are improved without damage to fibres. Hocker provides an overview of modern techniques, mentioning what is perhaps the most notable development, the use of supercritical fluid dyeing. This consists of using a gas (almost invariably carbon dioxide) in its supercritical state, under extremely high pressure and at an elevated temperature, to act as a solvent for the dye molecules. The fluid is very mobile and can penetrate the fibres easily, carrying the dyestuff with it. Once it has achieved this aim, a reduction in pressure immediately turns the solvent liquid back to gas, which escapes into the air, leaving the dye molecules in place on the fibres. Sekar55,56 reviews various uses, including sizing and desizing as well as dyeing, while Watanabe et al.57 find that polyester dyed in this way acquires a much deeper colour. Holme58 also recommends its adoption in conjunction with reactive disperse dyes (with their sulphonyl azide group) for polyester, polyamide, polypropylene and wool dyeing. In Fig. A.7, Riva et al.61 show the effects of dyeing time on percentage exhaustion and colour difference. Giehl et al.59 agree, because of the ecological advantages conferred by the method, but point out that new solvents and dyes should be sought and that a modifier is needed with reactive disperse dyes to give optimum results. Smota and Zupper60 find that slight changes in fibre orientation can occur, depending on the temperature and pressure during treatment, but they feel that these are not major and are probably caused by the equipment used. Despite the optimism engendered by this new technique, however, it should not be forgotten that carbon dioxide has to be manufactured before it can be compressed (at relatively high energy costs) and is a problematic greenhouse gas when released. Yet another suggestion is the adoption of enzymes, in place of chemicals, for various wet processing treatments. Riva et al.61 compare the effectiveness of three enzymes, in terms of absorption rate, colour depth and washfastness, finding that absorption and diffusion are both enhanced and, perhaps more importantly, dyeing can be carried out at a considerably lower temperature. Etters62 notes the reduced environmental stress resulting, while Karmaka63 investigates the effects of enzymes on various other treatments on cotton or wool. Chapter 7 also deals with the reduction of harmful emissions in textile dyeing. Dong et al.64 attempt to dye and finish (durable press) cotton in a single bath with a reactive dye and citric acid. Factors influencing the success of the operation include the concentrations of dyestuff, citric acid, catalyst or alkali, together with the temperature. They evaluate colour, crease recovery, tensile strength and fastness, finding that the single-step process imparts satisfactory results with

A.7 Effect of dyeing time on percentage exhaustion and colour difference; (a) contains key to all parts (source: JSDC 115 (1999), p 126. Reprinted with permission from the publisher, the Society of Dyers and Colourists, Bradford, UK).

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careful adjustment of conditions, but suggest that further study would be beneficial. Hauser and Tabba65 improve economic and environmental aspects of cotton dyeing simultaneously by adding cationic dye sites to the fibre, using a specific quaternary ammonium compound. Excellent dyeing results are achieved without using any of the electrolyte, multiple washings or fixation agents normally needed. The testing is carried out with direct, reactive and acid dyes, taking a shorter time than usual, but acid dyes are not as washfast on the cotton as they are on nylon. Phillips et al.66 compare chromium and cobalt compounds for their effectiveness as metal complex additives in dye fastness. They wash dyed fabrics in detergent containing an oxygen bleach, finding that both compounds give acceptable results at 50oC, but that some of the cobalt-containing ones fail a washfastness test at 60oC while chromium-treated dyes pass. They conclude that cobalt-complexed dyestuffs are more sensitive than chromium-complexed ones. Hauser67 introduces cationic dye sites into cotton to allow dyeing to be carried out in a more energyefficient, low-polluting manner by improving the affinity of dyes. This step eliminates rinsing and after-washing steps while increasing productivity. The usefulness of the suggestion can be envisaged from Fig. A.8, in which the time, chemical discharge, effluent volume and energy consumption are all seen to decrease significantly as a result of the cationic treatment. The large savings obtained in effluent, chemical use and energy are quantified in the paper.

Section 6 Medical applications of textiles Medical applications of textiles, as mentioned in Chapter 8, are widespread today. Hilgers68 divides them into three types, those external to the body or intended to be transplanted into it, those in the healthcare field and those strictly concerned with hygiene. The author focuses on the second of these types, including protective barrier clothing or drapes, bed linens and towels, with information on how to get the best wear, laundering and reuse of articles by selecting conditions for washing, disinfecting and sterilising properly. Medical clothing includes a new helmet, made from Hytel,69 to protect from micro-organisms, and new fabrics for barrier clothing in gowns or drapes. Conditions for making satisfactory fabrics for safe surgery are laid down70 as resistance to liquid water with good moisture vapour permeability (a suggestion put forward71 some years ago) to allow comfort to be maintained during surgery. Another writer72 recommends polyimide sandwiched between two layers of fabric to produce a barrier cloth with the required permeabilities, combined with light weight, flame resistance, flexibility and a pleasant handle for extended wear times. Yet another author73 feels that electrostatic charging of non-wovens, followed by sterilisation in ethylene oxide, can achieve the same desirable properties of breathability and comfort combined with filtration efficiency. Internal uses of textiles are focused mainly on grafts or implants in modern medical practice and are dealt with in some detail by Ramakrishna74 in a

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A.8 Effect of cationic treatment on process time, chemical discharge, effluent volume and energy used in cotton dyeing (source: ref. 67).

comprehensive survey of the many types of body parts currently being placed into human beings. Kaisha75 reports a puncture-proof, three-component layer material for use in a dialysis graft or artificial blood vessel. Ellis and Butcher76 adopt embroidery techniques for implants that have been tested as graft stents and orthopaedic implants for shoulder or neck disc repair, as well as in general implants. Other authors77 use two threads with different elastic moduli as the basis for a type of graft that can provide good simulation of the biomechanical behaviour of arterial tissue, while Daumer and Planck78 discuss the development of materials for implants to meet German standards. A new fabric developed for the repair of abdominal aortic aneurysms that can resist long-term changes, even though it has a lower-than-usual wall thickness, is also reported.79 One interesting suggestion80 is the use of a woven or knitted fabric made from bioresorbable fibres and treated with a biocompatible film that can be implanted to aid in the regeneration of body damage or in the controlled release of a drug. Other textile applications in medicine include a novel wound dressing81 that can provide sustained release of an antimicrobial compound over an extended period of up to eleven days with the preferred agent, chlorohexidine, and use of a silk material,82 for covering wounds (notably from burns), that can accelerate the growth of new skin while preventing bacterial entry. An ultrafilter made from nonwoven materials with hydroentangled fluoropolymers is devised83 to provide

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improved ultrafiltration for liquids (especially blood) or gases that can be used for face masks, diaper interfacings and wound dressings. In this type of hygiene area, too, the requirements of diaper absorbency, together with the similar needs of feminine hygiene products and incontinence pads, are addressed by Daniels84 and another author.85 It should be pointed out, incidentally, that the use of disposable diapers is one of the major problems facing the planet today; their ready disposability creates an enormous amount of waste that can rapidly fill up dump sites, and their composition is such that separation into recyclable components, apart from being an extremely unpleasant task, is difficult or even impossible to carry out effectively. Finally, there is an additional area of work that, though often neglected, is important in many health care situations. The noise levels in hospitals or nursing homes are targeted by Ahuja,86 who reports the development of new curtains containing acoustic-absorbent panels sandwiched between fabrics as a means of achieving a 7 dB reduction in noise levels.

Section 7 Textile filters Textiles as filters are frequently found in various types of use. Air cleaning is typified by the work of Reddy and Sastri,87 who use a geotextile as a filter in the separation of fly ash produced from coal burning at a power plant. They adopt the novel strategy of mixing the ash with water and decanting the slurry through the filter, a procedure that minimises the escape of pollutants into the air. One author88 describes the production of better filter webs with smaller pore size and improved elasticity, suggesting electrostatic charging as a means of attracting dirt more easily to the filter, while another89 recommends non-wovens made from thermoplastic microfibres made by a solvent-blowing technique to produce a non-toxic filter that is claimed to be 99.995% effective. Hollow fibres made from polyether ether ketone (PEEK) or (with less effective results) polyphenylene sulphide (PPS) are also suggested by Vorbach et al.90 for use in hot gas separation at up to 200oC to isolate nitrogen from carbon dioxide and argon. Yet another writer91 suggests that ceramics, metals and glass provide the best options for hot gas separation.

Section 8 Sporting goods and other uses In sporting goods, there are also examples of textile applications worth noting. Bacskai92 describes their use for extremely large tents at a tennis tournament, while one industrial manufacturer93 reports the use of a textile cover for a football pitch. Abend94 lists various uses of textiles in pleasure boating, discussing developments in this specialised field. A fibreglass-reinforced plastic coating for submarine hulls, to reduce corrosion, also appears.95 Perhaps the most satisfying use reported96 is that of a mat with aluminium strips woven into it to deflect solar radiation upwards from the ground in a French vineyard. The energy impinges on the grapes, raising their temperature by a couple of degrees to encourage an early harvest; the

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need for pesticides and herbicides is said to be dramatically reduced, so we can happily approve of this application on environmental grounds, not just the more obvious hedonistic ones.

Section 9 Effluent treatment Techniques for environmental protection by the removal of pollutants before discharge into the air or water are dealt with in Chapter 9. Chemical methods before discharge into aqueous surroundings are typified by the work of Lopez et al.,97 who recommend ozone. Hassan and Hawkyard98 decolourise spent reactive dye with ozone and reuse the liquor in bleaching, whitening and dyeing, finding that little modification beyond adjustment to the pH is needed. They use the process repeatedly with no difficulties, with application in peroxide bleaching of cotton, whitening cotton with optical brighteners and disperse dyeing of polyester. Figure A.9 compares the whiteness index of cotton treated with the ozonated effluent with that of a control test. Ramasamy et al.99 investigate the effects of temperature on ozonation of textile waste effluents. They find that higher temperatures reduce colour level (71.3% removal at 50oC), chemical oxygen demand (COD) (20.3%) and total organic carbon (TOC) (19.3%), and so recommend that no attempt should be made to dissipate the heat of the effluent

A.9 Effect of repeated use of recycled dye liquor on whiteness index of cotton (source: Textile Chemist and Colorist & American Dyestuff Reporter, Vol 32 No 6, June 2000, pp 44–48; reprinted with permission from AATCC).

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(currently emitted at a temperature of about 45oC) before discharging it to the ozone treatment plant. Mock and Hamouda100 go so far as to state that ozone is the only viable technology for decolourisation of waste water. Kuai et al.101 disagree, recommending an aerobic/anaerobic sequential treatment of waste water to bring about a reduction of up to 90% in COD and 95% colour removal. Arslan and Balcioglu102 try to achieve degradation of dyes in two ways, using either ozone, hydroxide ions and ferrous or ferric ions with hydrogen peroxide or, alternately, titanium dioxide and ultraviolet radiation. They assess TOC, BOD and spectrophotometric measurements, finding that the first technique is far superior to the second one because it gives better decolourisation and better demineralisation. Gregor103 treats dyehouse waste water with ozone and ultraviolet radiation, accompanied by the use of hydrogen peroxide to produce an effluent suitable for reuse in production processes. Kos and Perkowski104 use ozone and hydrogen peroxide to treat waste water that is highly resistant to biodegradation and find that, with ultraviolet radiation, the ozone can produce biodegradability. Optionally, both ozone and peroxide can be used simultaneously. Uygur and Kök105 also report work involving the decolourisation of azo dye waste water by means of ultraviolet radiation and hydrogen peroxide, confirming the logical expectation that decolourisation times are diminished when ultraviolet radiation levels and concentration of hydrogen peroxide are increased. They achieve a 98 to 99.5% removal rate and state that biological oxygen demand (BOD) is increased, while total organic carbon, total inorganic carbon (TOC), total carbon (TC) and adsorbable organohalides (AOX) are all decreased after treatment. These observations are explicable if one assumes that the dye molecules are broken down into carbon dioxide, water and smaller colourless molecules, thus producing more biodegradable products. The authors therefore recommend using oxidative decolourisation before attempting biodegradation treatments, and find that the water/ sodium sulphate residue from the treatment is reusable for dyeing. Figure A.10 shows the effect of a change in hydrogen peroxide concentration on the decolourisation rate in the presence of 1500 W of ultraviolet radiation and Fig. A.11 gives the visible and ultraviolet spectra of coloured and decolourised waste water from Procion Blue MX-2R, a reactive dye. The absorption taking place is readily observable in the latter diagram. Hardin et al.106 decolourise waste water without ozone or precipitating agents by making use of white rot fungi. They investigate the effectiveness of nine varieties of fungus on four types of dyes (acid, vat, direct and reactive), finding that colour disappears in five to twenty one days, or faster in a nitrogen-limited situation. Wang and Yu107 also suggest white rot fungus for extraction of dyes. Tiedermann and Schad108 control oligomers from polyester dyeing by reduction under optimum temperature/time conditions, and Krull et al.109 adopt chemical and biological controls in conjunction. In a different approach, Cheng et al.110 suggest the use of soilless culture methods to eliminate phosphorus and nitrogen, claiming that the simple equipment needed is inexpensive, easy to use, flexible in operation

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A.10 Effect of hydrogen peroxide concentration on decolourisation of dye waste waters (source: ref. 105).

A.11 Visible and ultraviolet spectra of coloured and decolourised waste water (source: ref. 105).

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and economical in energy use. Lin111 sounds a word of caution, noting that the ionexchange technique that he prefers is extremely expensive. This is a common problem with all methods if complete colour or dye removal is expected. Perhaps for this reason, biological techniques appear to be gaining in popularity. Churchley et al.,112 in a series of articles on the bioelimination of dyes, explain the mechanisms involved and note that there is a wide range of bioelimination levels, depending on the molecular structures of the dyes. They find a much lower reduction in dye concentration for reactive dyes (25%) than for direct (95%) or acid (96%) ones. Biolfiltration is recommended by one author113 to treat a dye/ finish effluent, using an activated foam to give high surface area for the support of bacterial activity. Sarsova and Janitza114 develop an aerobic biological procedure for effluent purification, in conjunction with adsorption on coke, while others115 prefer a culture that is anaerobic in nature, claiming a removal rate of up to 97% at the optimum state of operation. Jager,116 in an article dealing with the environmental management of plants, suggests the use of biological assessments for the optimisation of waste water and the development of ecological tests with a selection of dyes and chemicals. Heine and Hoecker117 provide some discussion of the ways in which enzymes interact with natural fibres and describe various finishing treatments in which these substances are used. Evaporation technology is used118 to depollute effluents in wool scouring, and the suggestion is made that there may well be a possibility of extending the approach to dyehouse and flax-whitening processes. Waste water is the subject of a paper, written anonymously,119 dealing with emissions from a plant where stonewashing and fading of jeans are carried out. Cotton and wool dyeing and fulling of wool are involved, and a wide range and concentration of solvents, organic substances, dyes and surfactants is used. Treatment involves settling to deposit pumice that would otherwise contaminate the fabric, followed by sifting and biooxidation in activated sludge, using sedimentation to allow any impurities to settle and, finally, treating the sludge before discharging the waste liquid to the environment. Ströhle and Pröll120 put forward a new concept for continuous splitting and desizing bicomponent fibre yarns, using continuous desizing with steam and water. Schneider121 notes that, in the biodegradation of viscose, finishing treatments (with the notable exception of resins) have no significant adverse effect. Halliyal et al.122 evaluate methods of solid waste disposal in silk reeling, finding that there is still no satisfactory method to accomplish this aim. In examining the possibilities of re-use in processing, an anonymous writer123 feels that the traditional techniques are unlikely to be completely successful, so recommends others (and especially flotation, in which solids float and are skimmed off) as being more likely to produce reusable water at a lower cost. Broglio124 also recommends the idea , especially where surfactants are used to assist in processing, while Raikar et al.125 study biodegradation and aquatic toxicity of surfactants. One writer126 expects that a biodegradable fibre will soon be able to compete economically with polyester. Zhang127 surveys the quality of waste water from a

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dye factory, together with the methods available to reuse it and/or reduce the amount of effluent released. Another writer128 recommends the recycling of waste water from a dye works because waste water represents a large use of a scarce resource. He feels that, because traditional methods cannot be guaranteed, sophisticated ones (such as flotation, with the water then recycled in the production process) are needed. A second anonymous author129 also favours recycling waste water from dyeing and recommends that, since the traditional methods used to purify water do not represent good energy use, it is advisable to adopt other approaches, flotation again being the one preferred because it can give better quality at lower cost. White et al.130 report an automated analysis system used in automated dyebath reuse for nylon carpets, in order to save water, energy, chemicals and (naturally!) money. Koh et al.131 reuse the dyebath effluent from nylon dyeing operations for ten cycles by reconstituting it to the original concentrations of dyes, auxiliaries and acid donors after ultraviolet/visible spectroscopic analysis. They measure colour reproducibility, levelness and fastness, finding that hydrolysable organic esters (ethyl lactate is the one they prefer) are superior to the conventional ammonium sulphate or sodium dihydrogen phosphate as acid donors. No deterioration in colour fastness is observed after the ten cycles. Uygur132 examines the feasibility of reusing waste water from azo dyeing by adopting an advanced oxidation method in which hydrogen peroxide and ultraviolet radiation, at a power level of 1000 W, are applied to the fabric, followed by removal of the excess peroxide. Decolourisation is achieved to a value of 98.3%, but the ability to adopt this treatment is limited to one reuse only. However, Bide et al.133 propose that, although dyebath reuse should be strongly advocated as a means of pollution prevention, the idea has a limited applicability because unevenness of dyeing begins to be evident after about six uses and, even with this limitation, very careful pH control is needed. Kozlov and Zuikova134 adopt a membrane method to treat dye effluent and use the treated water successfully as a wash-off liquid in sulphur dyeing, claiming significant reductions in energy and water consumption. Lin and Lin135 combine ultrafiltration with activated carbon adsorption and ion exchange, at the optimally determined range of all components, to achieve water of very good quality for reuse; the cost can be assumed to be prohibitive and, in view of the number of papers dealing with the subject, it is clear that the solutions proposed to date are not effective enough to satisfy the ecological criteria necessary to preserve the planet unharmed.

Section 10 Recycling The difficulty of recycling sizes attracts the attention of Stegmaier et al.136 who report that some of the newer ones can be recycled for up to five uses without becoming too unstable to provide satisfactory re-use. Klinkert137 carries out an

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investigation of the hydrogen peroxide treatment of starch sizes and other components in mercerisation lye, finding that the flotation principle (in which solid impurities are floated by carbon dioxide generation, to be skimmed off) is an invaluable aid in this work. An anonymous author138 uses a high vacuum technique to eliminate spin finishes in polyester and nylon recycling, providing a description of the sequence of operations in the process and noting that viscosity loss is reduced. In aiming to reduce pollution by more esoteric means, Kint and MunozGuerra139 review biodegradation processes for polyester, noting that most of them focus on hydrolysis at high temperatures. They also investigate the application of this type of treatment to copolymers (block and random) and blends. Adanur et al.140 discuss the recovery and re-use of PVC (polyvinylchloride)-coated polyester, noting the stages necessary; these include swelling, separation by the use of a solvent and removal of glue. The resulting material is used to reinforce epoxy resin or needle-punched non-wovens. An anonymous author141 is able to recycle thermoplastic fibres without the need for a spin finish by the use of high vacuum. It is preferable, though, to ensure that drying and melting are carried out without oxidation to minimise discoloration, and the use of a vacuum during the drying reduces the risk of significant viscosity loss. Artzt142 sounds a word of caution in making the point that the fall-out fibres from cotton are not economically worth reprocessing, something that may well become applicable to other materials if costs of recycling continue to escalate. The recovery of recycled components from carpets is currently one of the more interesting developments in the effort to make textile production less ecologically harmful. An overview of the subject is given.143 Sellers,144 in reporting the development of a new initiative in recycling carpets, cites as example the conversion of polypropylene carpet backing materials to geotextiles. The range of steps needed is documented145 and includes collection, identification, sorting and recovery of chemical materials or polymers; the increased energy recovery from, for instance, carpet backing is also noted. Griffith et al.146 carry out the separation and recovery of nylon from carpet waste by supercritical fluid extraction. Solution of nylon is obtained in formaldehyde at 40oC, after which recovery of the nylon powder by antisolvent precipitation at 84 to 125 bar at 40oC can be carried out, then solvent and antisolvent can be recycled. Zhang et al.147 claim that there are many commercial uses for recycled carpet materials, as long as the separate components are dealt with individually, giving compression moulding as their preferred technique for preparing useful recycled units. Vion148 proposes the use of a single fibre type, polypropylene, in making carpets to simplify the recovery chemistry and suggests that coating materials should be adopted to enhance the process. Powder coating technology is also recommended by an anonymous writer149 claiming that floorcoverings in general can provide the environment with increased resources in the form of lower energy consumption or simple recycling. The types of product that can be made by a recycling operation

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include acoustic panelling (in conjunction with wood chips150), new types of moulded products151 and even caprolactam, the raw material from which nylon is made and from which the fibre can be produced again, by means of an environmentally benign technique using steam at medium pressures.152

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Index

abdominal, 195 abrasion, 4, 7, 37, 61, 62, 75, 122, 125, 126, 127, 128, 129, 131, 132, 133, 134, 162, 163, 164, 167, 171, 189, 191 absorption, 6, 15, 32, 62, 63, 78, 86, 116, 119, 120, 121, 142, 145, 146, 156, 163, 164, 165, 168, 169, 170, 173, 175, 183, 187, 189, 192, 196, 198 accessories, 91 acetates, 32, 78, 110, 154, 162 acetone, 33, 162 acid, 27, 33, 35, 48, 58, 71, 80, 84, 87, 112, 117, 118, 131, 144, 152, 153, 154, 155, 157, 159, 187, 189, 190, 192, 198, 200, 201 acoustic, 18, 55, 56, 64, 96, 134, 170, 175, 196, 203 acrylic, 36, 37, 96, 158 acrylic sulphide, 36 activated, 35, 200, 201 activated carbon fibres, 35 activity, 5, 6, 14, 20, 29, 32, 37, 72, 95, 102, 104, 111, 131, 157, 158, 159, 169, 178, 181, 183, 200 additives, 25, 43, 109, 194 adhesive, 74 adsorption, 74, 82, 110, 117, 163, 189, 198, 200, 201 aerobic, 100, 198, 200 aerospace, 94 aesthetic, 74 affinity, 194 after-treatment, 72

agitation, 63, 70, 92, 131, 183 agitators, 64 agricultural, 15, 30, 136, 155, 168, 169, 179, 181 agrotextiles, 94 AIDS, 167 air, xiv, 2, 4, 6, 7, 9, 12, 18, 19, 21, 22, 25, 30, 32, 33, 48, 49, 53, 58, 70, 92, 93, 94, 95, 100, 102, 103, 107, 108, 110, 115, 117, 118, 128, 131, 134, 139, 140, 141, 142, 143, 144, 146, 157, 162, 167, 169, 170, 174, 178, 181, 192, 196, 197 airbags, 95 aircraft, 55, 96, 170 airflow, 141, 167 aldehyde, 117 aldicarb, 169 algae, 93 alkalis, 26, 33, 35, 36, 43, 44, 72, 75, 93, 108, 112, 153, 154, 155, 162, 183, 189, 190, 191, 192 alkanes, 85 allergenic, 7, 37, 58, 82, 156, 158 alloys, 118 alumina, 189 aluminium, 150, 196 ambient, 2, 5, 33, 58, 102, 110, 115 amines, 78 ammonia, 36, 82, 85, 99 anaerobic, 107, 198, 200 analysers, 164 analysis, 25, 66, 100, 146, 150, 172, 201 aneurysms, 195

207

208

Index

aniline, 106 animals, 2, 3, 4, 5, 6, 7, 10, 11, 12, 14, 15, 16, 23, 30, 31, 40, 42, 51, 58, 93, 104, 133, 156, 157 anionic, 85 anthraquinone, 106 antibacterial, 37, 73, 99, 158, 159 anti-foaming, 85 antimicrobial, 37, 75, 156, 158, 195 antimony, 76, 150 antisolvent, 202 antistatic, 74, 75, 144 aortic, 195 aphids, 24 apparel, 99, 127, 128, 165, 176, 190 appearance, 10, 42, 67, 70, 74, 94, 104, 145, 152, 156, 171, 180 aquatic, 6, 16, 21, 63, 93, 200 aqueous, 3, 72, 131, 183, 197 arachne, 66 architectural, 94, 96 argon, 36, 196 armed forces, 13 armouring, 168 arterial, 195 asbestos, 34, 36, 58 ash, 149, 196 asphalt, 94 assembly, 1, 54, 82, 126 assists, 179, 183, 192, 200 asthma, 58, 166 atmosphere, 1, 2, 3, 10, 12, 16, 19, 20, 30, 36, 48, 54, 64, 79, 103, 109, 115, 117, 118, 119, 120, 170 atomic, 7 attack, 3, 12, 48, 99, 130, 131, 132, 133, 134, 135, 147, 152, 154, 155, 157, 158, 161, 162, 163, 168, 171, 174 audit, 65, 109, 110, 111 auditing, 109, 111 auditory, 178 automation, 30, 40, 49, 106, 143, 201 automotive, 94, 95 auxiliaries, 16, 37, 84, 88, 190, 201 awareness, 4, 86, 99, 100 axle, 118 azo, 84, 100, 107, 191, 198, 201 backing, 202

bacteria, 1, 3, 11, 37, 42, 76, 155, 157, 158, 159, 160, 166, 169 bacterial, 3, 157, 158, 167, 195, 200 bactericidal, 158 baking, 73, 79, 154 balance, 7, 9, 10, 16, 21, 63, 93, 110, 161, 169 baling, 24, 48, 49, 52, 53, 126, 179 ballistic, 168 bandages, 11, 96 barrages, 128, 173 barrier, 64, 74, 90, 150, 158, 166, 167, 170, 171, 173, 194 basalt, 35 bases, 10, 17, 18, 67, 71, 84, 152, 155, 190 bast, 5, 23, 26 bath mats, 93 beach, 154, 172 beaming, 17, 62, 63, 94, 144 bearings, 18, 24, 118 bedding, 11, 37, 90, 133 beetles, 78, 155, 156, 163 beetling, 69, 71 bellows effect, 167 bending, 108, 124, 125, 126, 128, 190 benefits, 20, 43, 59, 71, 82, 85, 100, 101, 144, 150, 190 bentonite, 189 benzoyl, 78 bicomponent, 200 biocompatible, 195 biodegradation, 34, 82, 108, 169, 172, 198, 200, 202 bioelimination, 200 Biolfiltration, 200 biological, xiv, 2, 24, 57, 72, 75, 76, 78, 100, 106, 108, 110, 117, 134, 166, 169, 180, 189, 198, 200 biomechanical, 195 biooxidation, 200 biopesticides, 30 bioresorbable, 195 bioscouring, 183 biosphere, 1 biotechnology, 24 biowashing, 190 birefringence, 85 bituminous, 72

Index blame, xiv, xv, 8, 16, 57, 110, 178, 179 blankets, 91, 107, 108 bleaching, 15, 26, 33, 42, 43, 44, 46, 63, 75, 91, 92, 93, 106, 120, 152, 153, 154, 155, 158, 159, 162, 164, 179, 187, 189, 194, 197 bleeding, 46 blend, 34, 42, 53, 79, 108, 110, 156, 164, 189, 190, 191, 202 blinds, 164 block, 34, 86, 165, 202 block copolymer, 34 blood, 1, 3, 4, 55, 58, 160, 167, 195, 196 boat, 96, 154, 196 BOD, 198 body, 1, 2, 3, 4, 6, 11, 12, 14, 72, 86, 93, 95, 118, 127, 131, 133, 134, 146, 152, 155, 157, 162, 181, 194, 195 boll weevils, 24 bomb, 168 bonds, 46, 61, 67, 78, 79, 86, 120, 121, 122, 123, 139, 145, 149, 150, 158 boron, 147, 150 bound water, 142 braiding, 61, 65 brain, 2, 3, 16, 56, 96 breakage, 6, 30, 54, 61, 62, 67, 70, 120, 121, 126 breathable, 74, 167, 169, 194 breathing, 6, 7, 16, 19, 53, 66, 94, 178 brighteners, 46, 197 brightness, 82 brittleness, 117, 122, 145 bromine, 80, 150 brushing, 69, 70 BTTG, 168 budworms, 24 builders, 93 building, 20, 80, 94, 147, 174 buildings, 7, 15, 163, 170 bullet-proof, 168 bungee, 96 bunting, 132 burning, 19, 20, 80, 81, 109, 118, 146, 147, 149, 164, 167, 195, 196 bursting, 10, 52, 80, 90, 120, 121, 124, 127, 133 bushes, 24 butanetetracarboxylic acid, 71

209

by-products, 19, 20, 32, 40, 44, 48, 49, 63, 73 calcium, 106, 154 calendering, 69, 71 camels, 4 camouflage, 12, 13 canals, 172, 174 cancer, 7, 36, 58, 164 capping, 171 caprolactam, 203 caps, 10, 54, 171 carbohydrates, 157 carbon, 2, 4, 5, 7, 20, 34, 35, 49, 58, 59, 66, 80, 81, 82, 85, 94, 117, 118, 120, 125, 131, 146, 147, 150, 178, 192, 198, 201 carbon dioxide, 2, 4, 5, 20, 49, 58, 59, 66, 85, 118, 131, 150, 178, 192, 196, 198, 202 carbon monoxide, 7, 81, 85, 147, 150 carbon-carbon bonds, 120 carbonising, 36, 46, 48, 106, 153, 179 Carbosol, 48 carcinogenic, 16, 37, 49, 76, 79, 81, 84, 86, 93, 100, 106, 159, 179, 191 carding, 53, 126, 179 carpets, 67, 78, 93, 95, 96, 108, 128, 132, 152, 155, 156, 162, 163, 180, 201, 202 cars, 8, 55, 152, 168, 170 casein, 190 catalysts, 44, 80, 99, 192 cationic, 84, 85, 87, 158, 194 caustic, 187 cells, 2, 3, 7, 21, 140 cellulases, 183, 190 cellulose, 44, 78, 79, 158, 189, 191 cellulosic, 34, 46, 75, 153, 157 ceramic fibre, 36 ceramics, 34, 35, 196 chair, 127, 128 channels, 172 charging, 194, 196 charring, 149, 150 cheese, 158 Chernobyl, 21, 104 chimgel, 190 chimney, xiii, 86, 104, 112

210

Index

chips, 26, 32, 203 chitosan, 160 chloride, 154 chlorination, 104, 150, 163 chlorine, 36, 44, 46, 80, 153, 158, 162, 189 chlorocarbons, 93 chloroform, 162 chlorohexidine, 195 chromium, 76, 84, 194 chrysalis, 27, 30 citric, 71, 192 clays, 107, 171 cleaning, 6, 19, 25, 30, 36, 42, 43, 44, 46, 48, 53, 58, 93, 96, 99, 106, 107, 111, 133, 154, 181, 187, 196 cliff, 128, 172 climate, 13, 16, 26, 31, 91, 103, 141, 157, 164, 181 climbing, 96, 128, 129, 131 cling, 163 closed structure, 140 closed-cell, 140 cloth, 11, 12, 13, 17, 59, 70, 71, 78, 79, 88, 118, 120, 127, 128, 141, 142, 143, 144, 146, 155, 158, 159, 162, 166, 168, 191, 194 cloth temperature, 142 clothes, 92, 118, 155, 156 clothing, xiii, 11, 13, 30, 36, 68, 70, 88, 90, 91, 92, 93, 94, 95, 96, 99, 100, 108, 117, 126, 128, 130, 131, 134, 147, 150, 151, 152, 154, 157, 158, 163, 164, 166, 167, 168, 169, 180, 194, 204, 205 coagulation, 107 coal, 13, 14, 18, 19, 20, 118, 196 coastal, 173 coated, 94, 95, 96, 171, 202 coating, 58, 67, 73, 74, 80, 86, 88, 95, 118, 143, 162, 163, 164, 174, 196, 202 cobalt, 44, 194 cockling, 117, 142, 145 cocoons, 30 COD, 197 coir, 174 coke, 200 collar, 167

collected, 21, 86 colour, xiii, 26, 43, 44, 46, 49, 59, 69, 75, 81, 82, 84, 86, 87, 90, 91, 106, 107, 118, 120, 121, 145, 152, 153, 155, 156, 162, 164, 179, 180, 182, 192, 197, 198, 200, 201 colourfastness, 82, 191 combed, 53 combinations, 17, 24, 40, 54, 67, 72, 79, 95, 106, 107, 115, 116, 119, 122, 130, 131, 147, 165, 172, 183, 190 combing, 53, 54, 82 combustion, 19, 20, 49, 57, 81, 117, 147, 149 comfort, xiv, 10, 12, 37, 56, 73, 94, 137, 163, 165, 166, 167, 169, 175, 194 commercial, 29, 30, 43, 85, 92, 128, 145, 183, 190, 202 commitment, 98, 101, 180 competition, 11, 180 complex, 1, 9, 18, 22, 32, 35, 36, 49, 53, 54, 56, 62, 64, 65, 67, 78, 91, 93, 120, 125, 150, 152, 181, 194 comply, 174 composites, 94, 95, 96, 107 compression, 108, 123, 124, 126, 127, 128, 192, 202 compromise, 46, 74, 103, 175 computer, 8, 25, 69 concrete, 17, 21, 36, 94 condensation, 78 condensers, 58 conductors, 33 cone, 126 conference, 24, 25, 63, 99, 108, 150, 159, 163, 191 conservation, 101, 106, 192 construction, 74, 94, 95, 128, 136, 147, 164, 165, 167, 171, 172, 173 consumer, xiv, 8, 15, 23, 24, 31, 43, 44, 63, 68, 69, 74, 78, 88, 98, 101, 108, 111, 130, 137, 165, 191 consumption, 14, 21, 22, 58, 62, 65, 66, 67, 70, 82, 85, 100, 102, 104, 107, 112, 134, 144, 156, 183, 189, 194, 201, 202 containers, 19, 21, 108 containment, 156, 173

Index contamination, 3, 6, 7, 15, 21, 22, 24, 30, 31, 34, 40, 42, 43, 46, 48, 59, 118, 132, 154, 155, 156, 162, 169, 171, 189, 200 control, 18, 24, 25, 30, 33, 58, 69, 73, 84, 95, 100, 101, 106, 122, 143, 146, 155, 162, 172, 173, 174, 181, 190, 197, 198, 201 controlled atmospheres, 29 controlled temperature, 144 convection, 140, 167 convenience, 32, 182 converted, 21, 32, 65, 110, 117, 145, 189, 191 conveyor belts, 48, 96, 128, 152, 180 copolymers, 80, 202 copper, 11, 37, 44, 96, 106, 107 cordage, 13, 96, 128, 133, 180 cores, 174 corona, 82 corrosion, 18, 21, 22, 43, 94, 96, 118, 155, 171, 196 cosmic, 7, 10 costs, xiii, 18, 20, 21, 22, 25, 31, 33, 34, 37, 43, 49, 51, 54, 56, 57, 58, 65, 66, 68, 69, 70, 73, 74, 82, 85, 88, 91, 94, 96, 99, 100, 101, 102, 103, 105, 107, 108, 110, 111, 112, 118, 130, 146, 147, 171, 181, 187, 189, 191, 192, 200, 201, 202 cotton, 2, 5, 23, 24, 25, 26, 27, 30, 34, 38, 40, 42, 46, 49, 54, 58, 59, 60, 63, 71, 73, 75, 79, 80, 85, 101, 103, 108, 110, 113, 121, 136, 144, 151, 153, 158, 161, 166, 167, 169, 183, 189, 190, 191, 192, 197, 200, 202, 206 CPI starch, 190 cracking, 21, 32, 49, 117, 122, 191 creasing, 71, 75, 78, 79, 191, 192 creep, 172 crimping, 55 criteria, 55, 67, 100, 167, 172, 173, 174, 175, 191, 201 crocheting, 61, 65 crop, 24, 25, 30, 111 cross-linking, 36, 71, 79, 107, 191 crushing, 36, 123 crystal, 123 crystallites, 85

211

cuffs, 167 cultivated silk, 29, 30 cultivation, 25, 26, 181 curing, 36, 71, 158 curiosity, 13 curtains, 128, 132, 163, 175, 196 cushions, 12, 93, 96, 128, 173 cutting, 91 cyanide, 6, 81, 144, 147, 150 cystine, 156 damage, xiii, 2, 11, 14, 15, 16, 22, 26, 36, 40, 43, 44, 46, 49, 54, 56, 57, 62, 69, 73, 75, 76, 78, 81, 82, 90, 94, 96, 98, 105, 119, 120, 121, 122, 123, 127, 131, 132, 133, 134, 135, 140, 142, 144, 145, 146, 147, 153, 154, 155, 156, 157, 159, 160, 161, 162, 164, 170, 171, 173, 178, 179, 180, 181, 189, 191, 192, 195 damp, 71, 75, 78, 145, 157 dams, 20, 172 danger, 5, 7, 11, 19, 36, 44, 48, 56, 62, 78, 79, 80, 81, 84, 100, 104, 153, 166, 169, 175, 181 deafness, 57 death, 2, 3, 11, 12, 130, 159, 164 decating, 69, 71 decay, 157, 159 decibels, 56, 62 decolourisation, 100, 106, 107, 162, 197, 198, 201 decomposition, 15, 26, 33, 48, 116, 123, 144, 157, 189 defects, 110, 118, 156, 180 defence, 109, 163 deformation, 124 defuzzing, 190 degradation, xiii, 22, 44, 49, 76, 106, 115, 116, 119, 120, 123, 126, 130, 131, 132, 133, 134, 146, 149, 150, 154, 155, 161, 162, 171, 176, 198 degumming, 43, 190 dehydration, 3 delamination, 74 delustring, 164 demineralisation, 198 denaturing, 145 denims, 190

212

Index

denitrification, 107 density, 81, 94, 164 deodorants, 162 depletion, 14, 178 de-pollute, 200 depth, 19, 84, 192 designers, 92 desizing, 63, 75, 106, 190, 191, 192, 200 destruction, xiii, 2, 8, 10, 15, 16, 37, 44, 46, 87, 98, 104, 116, 121, 122, 124, 125, 145, 149, 152, 155, 156, 157, 158, 162, 174 detection, 59, 111, 170 detectors, 170 detergent, 16, 27, 30, 42, 44, 48, 58, 64, 69, 92, 93, 131, 154, 162, 194 deterioration, 7, 144, 201 detoxification, 169 dialdehyde, 71 dialysis, 195 diapers, 196 diatomaceous earth, 189 dieldrins, 44, 76, 78 diesel, xiii, 49 differential thermal analysis, 108 diffusion, 33, 85, 192 dilemmas, 175 dimensional changes, 99, 117, 118, 145, 155 dimensions, 58, 152 dioxins, 104 dirt, 7, 40, 42, 48, 58, 92, 93, 104, 110, 111, 118, 126, 131, 134, 189, 196 discards, xiii, xiv, 14, 15, 16, 18, 21, 30, 66, 70, 71, 74, 75, 78, 79, 84, 86, 87, 90, 91, 92, 93, 103, 104, 106, 116, 118, 127, 134, 137, 145, 149, 152, 154, 159, 179, 180 discharge, 21, 43, 48, 80, 81, 82, 86, 87, 93, 99, 103, 104, 106, 107, 112, 163, 194, 197, 198, 200 discolouration, 156, 158, 202 discomfort, 55, 73, 167 disease, 6, 11, 30, 44, 58, 156, 164, 167, 169 dishcloths, 133 disinfecting, 194 disintegration, 33, 34, 57, 121, 122, 153, 156, 157, 160, 173

disperse, 84, 87, 107, 192, 197 dispersions, 72 disposal, 20, 53, 72, 80, 81, 87, 92, 93, 96, 99, 100, 108, 112, 130, 166, 190, 196, 200 distortion, 17, 62, 79, 118, 124, 125, 145 disulphide, 76, 156 D-limonene, 183 DNA, 30 doffing, 25 domestic, 20, 58, 145, 156 dosage, 120, 183 drafting, 54 drainage, 171, 173 drapery, 90, 96, 133, 194 drawing, xiv, 14, 32, 33, 43, 54, 69, 126, 127, 141, 142, 164 dressings, 96, 196 drilling, 19 drink, 7, 158, 170 drive belts, 95, 96 drum dryer, 141 dry spinning, 31 drycleaning, 73, 80, 92, 93, 99, 131, 155, 159, 174, 180 drying, 40, 48, 71, 72, 87, 88, 92, 100, 122, 127, 131, 140, 141, 142, 143, 144, 145, 146, 147, 158, 162, 179, 202 drying rates, 144 dumping, 103, 196 durability, 94, 158, 169 durable press, 71, 192 dust, 6, 7, 15, 16, 25, 37, 40, 53, 54, 55, 57, 58, 59, 61, 62, 92, 134, 166, 169, 170, 179 mites, 37 dyebath, 191, 201 dyehouse, 81, 198, 200 dyeing, 29, 63, 75, 81, 82, 84, 85, 86, 87, 99, 106, 108, 127, 140, 153, 179, 183, 189, 191, 192, 197, 198, 200, 201 dyes, xiii, 24, 29, 46, 63, 72, 75, 76, 81, 82, 84, 85, 86, 87, 91, 99, 100, 106, 107, 118, 120, 121, 133, 147, 153, 155, 162, 164, 165, 169, 189, 191, 192, 194, 197, 198, 200, 201

Index E. coli, 5, 158 Earth Summit, 98 easy-care, 71, 78, 179, 190 Ebola, 167 eco-balances, 110 ecofashion, 101 eco-friendly, 29, 80, 81, 86, 189 ecolabel, 100 ecological, 7, 18, 19, 22, 31, 33, 35, 37, 51, 53, 54, 59, 63, 65, 67, 68, 71, 72, 74, 78, 81, 82, 84, 87, 92, 93, 96, 101, 103, 105, 110, 111, 112, 116, 134, 135, 141, 147, 150, 154, 159, 178, 179, 180, 181, 191, 192, 200, 201 economic, 27, 59, 104, 106, 111, 130, 135, 143, 179, 180, 191, 194 economy, 19, 49, 98, 103 ecosystem, 1, 2, 8, 9, 14, 16 education, 101 efficiency, 25, 40, 53, 64, 84, 95, 103, 107, 139, 141, 170, 191, 194 effluent, 43, 44, 64, 71, 78, 81, 84, 86, 99, 100, 103, 106, 107, 108, 133, 155, 179, 187, 189, 194, 197, 198, 200, 201 eggs, 155, 156 Egyptian, 24 elastic, 195 elasticity, 156, 196 electrical, 17, 18, 21, 36, 80, 82, 146, 163 electricity, 18, 19, 20, 21, 57, 139, 159 electrolyte, 194 electromagnetic, 15, 78, 96, 119, 120, 122, 150 electronic, 59, 154 electrostatic, 123, 194, 196 elongation, 27, 63, 190 embedded, 62, 70, 171 embrittlement, 162 embroidery, 18, 65, 195 emissions, 7, 10, 49, 62, 72, 79, 80, 85, 92, 98, 99, 102, 103, 104, 105, 106, 107, 110, 121, 122, 144, 147, 149, 179, 181, 192, 198, 200 emulsions, 72 end-group, 116, 125 end-products, 23, 31, 81, 136, 157, 163, 180

213

end-use, 69, 95, 100, 115, 134, 139, 162, 174 energy, xiv, 3, 4, 7, 14, 15, 18, 19, 20, 21, 22, 25, 32, 33, 34, 42, 48, 54, 57, 58, 62, 64, 65, 66, 67, 70, 71, 72, 78, 82, 84, 92, 99, 100, 102, 106, 107, 110, 116, 119, 120, 122, 123, 139, 140, 142, 143, 144, 145, 146, 150, 168, 170, 183, 189, 190, 191, 192, 194, 196, 200, 201, 202 enforcement, 30, 102, 104, 105, 169 engine, 57, 134, 170 engineering, 11, 17, 24, 30, 204 engines, 49, 53 entanglement, 65, 66 environment, xiii, xiv, 1, 6, 7, 8, 11, 17, 19, 21, 22, 26, 36, 43, 48, 53, 55, 56, 57, 58, 65, 66, 71, 72, 78, 79, 87, 90, 91, 93, 94, 96, 99, 102, 106, 108, 110, 115, 116, 123, 134, 136, 144, 147, 149, 150, 152, 156, 158, 161, 162, 164, 169, 171, 178, 180, 181, 200, 202 environmental, xv, 7, 8, 9, 10, 15, 16, 18, 22, 23, 25, 26, 29, 30, 31, 33, 34, 35, 36, 43, 44, 48, 51, 54, 56, 59, 61, 62, 63, 65, 66, 67, 69, 70, 71, 73, 74, 75, 78, 80, 81, 82, 84, 86, 87, 88, 91, 92, 93, 96, 98, 99, 100, 101, 102, 104, 105, 106, 108, 109, 110, 111, 112, 122, 130, 132, 134, 135, 136, 143, 145, 146, 147, 150, 155, 156, 158, 161, 163, 168, 169, 174, 178, 179, 180, 181, 183, 190, 191, 192, 194, 197, 200 contaminants, 7 costs, 8, 20, 22, 24, 25, 29, 30, 32, 48, 49, 54, 57, 62, 65, 66, 67, 70, 71, 75, 135 effects, xv, 15, 61, 101, 179 harm, 8, 44, 134, 135, 145, 178, 179 impact, 110, 136, 150, 191 policies, 99 environmentalists, 43, 98 environmentally-friendly, 46, 99, 100, 159, 183 enzymes, 22, 27, 43, 46, 63, 75, 106, 156, 157, 183, 187, 189, 190, 192, 200 epoxide, 71

214

Index

epoxy, 79, 94, 202 equilibrium, 1, 8, 9, 74, 142 equipment, 7, 18, 19, 20, 22, 26, 27, 32, 33, 34, 36, 48, 53, 55, 65, 66, 86, 103, 116, 122, 123, 136, 144, 155, 157, 169, 170, 178, 179, 182, 192, 198 erosion, 15, 16, 25, 90, 155, 171, 172, 173, 174, 181 erythema, 166 ethyl acrylate, 190 ethyl lactate, 201 ethylene, 46, 80 ethylene oxide, 194 Eulans, 76 Europe, 105, 108, 203, 205 European Union, 100, 101, 106, 166 evaporation, 32, 33, 85, 109, 118, 142, 189, 200 evenness, 7, 12, 123, 192 evolution, 11, 14, 15, 81, 86, 109, 144, 166, 190 excretions, 157 exhaust, 30, 49, 57, 84, 92, 102, 107, 192 expensive, xiii, 18, 20, 30, 35, 36, 64, 93, 96, 111, 146, 200 explore, 14, 15 explosion, 55, 57 exposure, 7, 35, 46, 56, 57, 75, 80, 102, 115, 116, 117, 118, 119, 120, 123, 129, 130, 131, 132, 133, 134, 137, 139, 140, 142, 145, 146, 150, 153, 154, 155, 156, 161, 164, 166, 167, 169, 170, 172, 175, 181, 189, 192 extension, 67 extraction, 13, 19, 22, 30, 32, 33, 34, 51, 63, 73, 75, 96, 179, 198, 202 extrusion, 23, 32, 33, 34, 37, 42, 67 eyesight, 165 factories, 19, 30, 48, 58, 69, 88, 92, 105, 169, 170, 181, 201 fading, 87, 118, 121, 133, 152, 200 failure, 7, 94, 102, 104, 116, 126, 129, 130, 152, 155, 172, 174, 180 falling-rate, 142 false twisting, 54 fashion, 13, 48, 91, 92, 130, 180 fastness, 82, 84, 121, 150, 192, 194, 201

fatigue, 22 felting, 61, 63, 65, 70, 80, 95, 127 ferric, 107, 117, 198 ferric chloride, 107 ferrous, 18, 117, 198 fertilisers, 15, 24, 25, 26, 30, 91, 132, 154, 179 fertility, 6 festoon, 141 fibre content, 164 fibre length, 25 fibre quality, 5, 25, 27, 82 fibrefill, 93 fibreglass, 94, 196 fibre-reinforced, 96 fibrous, 64, 109, 139, 142, 149, 179 filaments, 27, 30, 32, 33, 35, 43, 67, 108 film, 58, 61, 67, 73, 162, 195 film fibrillation, 61, 67 filters, 14, 36, 56, 96, 107, 173, 134, 155, 169, 170, 173, 196 filtration, 10, 13, 16, 53, 95, 100, 107, 155, 162, 169, 170, 194, 205 financial, xiv, 24, 54, 56, 66, 69, 74, 82, 84, 102, 104, 105, 111, 141, 145 fineness, 12 fines, 31, 32, 37, 42, 52, 53, 105, 111, 183 finishing, xiii, 7, 53, 54, 63, 67, 69, 70, 71, 72, 73, 74, 75, 76, 78, 79, 80, 81, 87, 88, 90, 99, 103, 104, 118, 127, 128, 133, 145, 146, 147, 150, 153, 156, 158, 160, 163, 164, 165, 166, 174, 175, 179, 190, 191, 192, 200, 202 fire, 7, 16, 19, 80, 81, 117, 118, 141, 145, 147, 150, 167, 170, 175 firefighters, 36, 167 fish, 6, 16, 21, 93, 99 fixation, 156, 194 flags, 128, 132 flame, 75, 78, 80, 81, 84, 144, 146, 147, 149, 150, 163, 166, 168, 175, 179, 194 flame retardants, 146, 150 flammability, 108, 146, 147, 149, 174 flax, 26, 27, 200 flexibility, 17, 18, 96, 190, 194, 198 flocculation, 107

Index flock, 86, 87 floods, 16 floorcoverings, 202 flotation, 16, 200, 202 flow, 18, 20, 21, 25, 32, 43, 90, 106, 140, 142, 143, 146, 155, 172, 181 flow rate, 142 fluff, 58, 127 fluorides, 76 fluorocarbon, 72 fluoropolymers, 119, 160, 195 fly, 12, 58, 109, 179 fly ash, 196 flyer, 54 foams, 100, 173, 200 folding, 95, 127 food, 2, 3, 4, 6, 7, 11, 12, 13, 29, 51, 66, 133, 156, 157, 158, 170, 178 foreign matter, 26, 59, 110 formaldehyde, 76, 79, 86, 94, 96, 149, 202 FP (flash point), 149 fragments, 26, 40, 57, 59, 122, 168 frames, 18 frequency, 2, 55, 56, 105, 117, 119, 120, 122, 123, 145 friction, 57, 58, 62, 71, 125, 127, 162 fruit juices, 154 fuel, 19, 20, 21, 49, 50, 57, 102, 107 fuller’s earth, 189 fulling, 69, 70, 106, 153, 200 fumes, xiii, 7, 19, 80, 103, 105, 133 fungi, 1, 37, 156, 157, 158, 159, 160, 198 furans, 104, 150 furnishings, 93, 147, 162, 163, 180 furniture, 8, 133 Gaia Hypothesis, 2 gamma, 120 gardening, 31, 132, 154, 162 garments, 2, 13, 36, 37, 71, 72, 73, 74, 78, 81, 91, 92, 93, 96, 117, 118, 127, 130, 131, 152, 156, 158, 163, 164, 165, 166, 167, 168, 169, 175, 180 gases, 3, 6, 10, 16, 18, 19, 30, 32, 33, 36, 49, 50, 57, 66, 73, 79, 80, 82, 85, 95, 102, 103, 109, 112, 118, 131, 133, 139, 142, 146, 147, 161, 174, 175, 178, 179, 191, 192, 196

215

gears, 18, 57 generation, 19, 20, 21, 22, 57, 73, 163, 202 genetic, 6, 7, 24, 30, 104 geosynthetic, 171 geotextiles, 15, 53, 90, 94, 96, 128, 132, 138, 152, 154, 155, 171, 172, 173, 174, 181, 196, 202 German, 58, 108, 191, 195 germicides, 76 gilling, 53, 54 ginning, 25, 103 glare, 165 glass, 1, 6, 34, 35, 80, 94, 163, 196 global warming, 16, 20, 66, 141 gloves, 167 glyoxal, 71 goats, 4, 30, 31 godet, 32, 33 Gore, 74 government, 6, 98, 101, 105, 111, 166, 182 gowns, 11, 74, 167, 194 grafts, 30, 81, 169, 190, 194, 195 gravity, 9, 18, 25, 32 grease, 40, 80, 189 green, 10, 24, 99 greenhouse, 49, 178, 192 greige, 69, 108 greying, 189 ground, 6, 14, 15, 18, 19, 30, 31, 34, 36, 75, 95, 131, 132, 155, 164, 171, 196 groundwater, 30, 171 growth, xiv, 6, 10, 16, 23, 24, 25, 29, 31, 35, 37, 58, 78, 93, 135, 157, 180, 195 guides, 126 gum, 30, 42, 43, 86 guns, 168 habitat, 15 hair, 23, 26, 31, 40, 153, 156, 162 halamine, 169 halogens, 80, 81, 146, 147, 150, 189 hammocks, 132 hand, 14, 18, 25, 26, 30, 32, 61, 65, 66, 104, 108, 109, 111, 135, 142, 152, 154, 155, 165, 168, 194

216

Index

handling, 32, 37, 107, 117 hand-picked, 30 harbour, 173, 181 hardness, 63 harm, xiv, 4, 5, 6, 7, 8, 10, 13, 15, 16, 21, 22, 26, 33, 37, 43, 46, 48, 49, 50, 56, 57, 58, 62, 64, 72, 75, 76, 78, 81, 82, 83, 84, 85, 87, 88, 91, 92, 93, 95, 96, 98, 99, 100, 102, 103, 104, 105, 106, 107, 111, 112, 115, 116, 117, 126, 134, 135, 137, 144, 146, 149, 150, 152, 153, 155, 156, 158, 160, 162, 164, 165, 166, 167, 169, 170, 175, 178, 179, 180, 181, 191, 192, 202 harnessed, 21, 25 harsh, 145, 163 harvesting, 22, 23, 25, 26, 27, 31, 40, 49, 136, 161, 196 hazards, 2, 6, 49, 58, 63, 75, 84, 94, 95, 99, 100, 132, 134, 158, 161, 163, 164, 166, 168, 169, 180 healds, 126 health, 2, 8, 11, 14, 15, 16, 19, 21, 58, 61, 93, 95, 98, 99, 100, 106, 122, 150, 163, 169, 191, 196 hearing, 55, 56, 57, 62 heat, 22, 30, 32, 33, 35, 36, 48, 63, 65, 69, 70, 80, 87, 92, 102, 107, 119, 131, 133, 137, 139, 140, 141, 142, 143, 144, 146, 147, 150, 162, 166, 167, 169, 174, 189, 197 heat retention, 140 heating, 33, 64, 67, 102, 133, 140, 144, 146 heat-setting, 145 heddles, 62 helmet, 56, 194 hemp, 26 herbicides, 24, 179, 197 holes, 32, 67, 76, 126, 127, 156, 157, 160, 162, 179, 197 holiday, 13 home, 11, 31, 40, 92, 93, 128, 132, 147, 155 home furnishing, 93 hosiery, 158 hospitals, 11, 196 household, 8, 93, 94, 100, 118, 129, 154, 162, 163

housing, 62, 66, 178 humans, xiv, xv, 2, 3, 4, 5, 7, 10, 11, 12, 13, 14, 15, 16, 49, 55, 56, 58, 66, 76, 78, 84, 90, 98, 100, 103, 118, 122, 123, 131, 133, 135, 137, 146, 147, 150, 152, 156, 157, 161, 162, 163, 164, 166, 169, 170, 171, 178, 179, 181, 195 humidity, 117, 161 HVI testing, 25 hydrochloric, 144 hydroelectric, 20 hydroentanglement, 53, 195 hydrogen, 21, 44, 81, 100, 147, 153, 159, 187, 198, 202 hydrogen peroxide, 44, 198 hydrogen sulphide, 110 hydrolysable, 201 hydrolysis, 72, 183, 202 hydrophilic, 48, 117, 158 hydrophobic, 48, 73, 80, 117, 158, 174 hydroxide, 37, 42, 43, 75, 153, 183, 187, 198 hydroxyl, 121 hygiene, 11, 93, 194, 196 hyperfiltration, 106 hypochlorite, 189 hypodermic, 168 ignition, 80, 146, 149, 150 illness, 2, 152 imbalance, 9 immune system, 3 impedance, 127, 140, 170 impermeability, 73, 168, 173, 174, 175 implants, 11, 65, 194 impurities, 2, 3, 19, 43, 44, 46, 48, 53, 54, 58, 110, 118, 154, 169, 170, 183, 200, 202 incompatible, 156, 175 incontinence, 196 indoor, 132, 154, 165 industrial, 8, 19, 56, 57, 58, 90, 91, 94, 95, 99, 106, 118, 128, 131, 136, 138, 152, 154, 155, 160, 166, 169, 173, 177, 178, 181, 182, 196, 204, 205 Industrial Revolution, 8, 19, 91, 178, 182 inert, 14, 35, 36, 96, 118 infections, 11, 31, 166, 167

Index infrared, 10, 58, 119, 122, 139, 142, 146, 165 injury, 152, 164, 169 inorganic, 34, 106, 107, 179, 190, 198 insecticides, 24, 132, 179 insects, 1, 24, 30, 31, 40, 75, 76, 78, 155, 160, 163 inspectors, 104, 105, 110 installation, 107, 171, 173, 174 instruments, 11, 42, 136, 166 insulation, 18, 35, 36, 56, 64, 66, 70, 94, 96, 134, 139, 140, 164 intensity, 11, 55, 56, 87, 102, 127, 139, 173 interaction, 1, 118, 121, 150, 200 interfacings, 196 interstices, 71, 79 intumescent, 150 ion exchange, 200, 201 iron, 11, 44, 66, 118, 189 ironing, 145, 162 irradiation, 48 irrigation, 25, 167, 172 irritation, 44, 158, 165 ISO, 168, 176 isolation, 13, 96, 118, 123, 124, 143, 166, 169, 181 jeans, 24, 191, 200 jet, 32, 65, 143 jute, 23, 26, 82, 172 keratin, 120, 156 kerosene, 86 Kevlar, 94, 168 kier, 106 knit-deknit, 55 knitting, 18, 61, 66, 89, 94, 96, 126, 128, 151, 160, 164, 167, 189, 190, 195 knives, 168 Kyoto, 98, 180 labelling, 67, 100, 123, 166, 169 labour, 25, 42, 58 lace-making, 61, 65 lagoon, 171 lake, 21 lamination, 61, 67, 73, 95, 167 land, xiv, 6, 9, 10, 13, 15, 18, 19, 20, 22,

217

25, 31, 34, 51, 75, 90, 112, 118, 173, 178 landfills, 90, 99, 108, 171 larvae, 155, 156 lasers, 42, 144 laundering, 73, 92, 110, 131, 133, 154, 158, 159, 174, 180, 191, 194 laws, 12, 102, 103, 104, 105 layers, 67, 74, 168, 174, 194 leaching, 15, 25, 81, 90, 171, 173, 181 lead, 15, 43, 44, 49, 84, 92, 106, 109, 134, 135, 152, 181 leaf, 26 leakage, 21, 84, 152, 168, 173 leather, 99 legislation, 6, 49, 56, 72, 80, 100, 102, 103, 108, 109, 112, 169, 180, 191 leisure, 61, 96 life, xiv, 1, 2, 3, 4, 9, 10, 11, 14, 15, 19, 20, 21, 22, 37, 40, 56, 70, 74, 75, 78, 92, 94, 96, 99, 110, 112, 116, 128, 136, 147, 150, 154, 156, 158, 167, 171, 172, 175, 180, 181 life expectancy, 128 lifestyle, xv, 57, 92, 164, 180 light, 5, 30, 53, 57, 72, 84, 95, 102, 110, 119, 121, 123, 133, 144, 150, 152, 157, 162, 164, 172, 194 lignin, 189 limiting oxygen index, 149 linen, 5, 23, 26, 40, 153, 154, 161, 190, 194 liners, 95, 171, 173 linseed, 72, 73 lipase, 183 liquid, 16, 32, 33, 36, 72, 73, 85, 87, 109, 118, 131, 133, 154, 155, 161, 164, 167, 169, 170, 171, 172, 174, 175, 189, 192, 194, 196, 200, 201 liquors, 30, 43, 44, 70, 84, 86, 107, 197 lobby, 98, 105 looms, 18, 62 loop, 141 lubricants, 22, 50, 53, 54, 58, 62, 75, 170, 191 luminescent, 166 lungs, 7, 19, 36, 58, 156, 169 lustrous, 43, 75, 153 luxury, 4, 14, 42, 178

218

Index

Lycra, 164 lye, 202 lyocell, 158 machine, 7, 25, 48, 54, 55, 57, 61, 62, 65, 66, 67, 92, 112, 118, 127, 131, 136, 141, 142, 169 machinery, 11, 18, 25, 29, 32, 34, 48, 49, 53, 54, 55, 56, 58, 62, 64, 65, 66, 67, 70, 71, 72, 74, 88, 91, 92, 93, 117, 118, 126, 127, 136, 181, 189 machinists, 168 magnesium, 159 main chain, 116, 145 maintenance, 17, 55, 57, 58, 93, 107, 130, 131, 159, 160, 161, 162, 168, 174, 180, 181 malimo, 66 maliwatt, 66 malvaceae, 172 management, 24, 69, 99, 101, 106, 110, 173, 200 manipulating, 18 manufacture, xiii, xiv, xv, 16, 17, 18, 19, 22, 29, 32, 33, 34, 35, 48, 62, 66, 67, 69, 74, 75, 80, 88, 90, 91, 93, 108, 110, 117, 126, 127, 134, 135, 136, 171, 175, 178, 179, 192 marine, 95, 96, 117, 132, 168 marketing, 29, 92, 95, 100 markets, 13 marquees, 154 masks, 196 mass production, 101 materials, xiii, 11, 13, 14, 17, 18, 21, 22, 23, 31, 34, 35, 36, 42, 49, 57, 58, 59, 63, 65, 66, 67, 72, 74, 80, 81, 88, 90, 91, 95, 99, 106, 107, 108, 109, 110, 115, 116, 117, 118, 119, 120, 122, 123, 128, 132, 133, 137, 140, 146, 147, 150, 151, 152, 154, 155, 156, 157, 161, 162, 163, 165, 166, 168, 170, 171, 172, 173, 174, 175, 179, 190, 195, 202 matrix, 37, 67, 96 matting, 174 maturity, 25 MDRP (maximum degradation rate point), 149

measurement, 25, 109, 110, 123, 130, 166, 170 mechanical, 8, 17, 22, 25, 26, 27, 34, 51, 57, 59, 61, 64, 65, 67, 69, 70, 71, 106, 115, 117, 118, 121, 123, 124, 125, 126, 127, 128, 130, 131, 134, 146, 162, 171, 174, 180, 183, 189, 190 medical, 11, 13, 15, 30, 39, 53, 65, 94, 95, 108, 163, 166, 170, 180, 181, 194 medical textiles, 95 medicine, 11, 195 melamine, 79 melt spinning, 31 melting, 10, 33, 34, 35, 202 membranes, 73, 74, 100, 201 mercerisation, 63, 75, 106, 153, 202 mercury, 76 merino, 187 metal, 13, 17, 34, 37, 49, 52, 66, 84, 86, 96, 106, 110, 118, 128, 131, 135, 141, 142, 167, 168, 170, 194, 196 metal oxides, 34 metallic, 72, 76, 78, 160 methane, 174 methonyl, 169 methylene blue, 183 microbiological, 37, 76, 78, 123, 131, 133, 137, 150, 155, 156, 157, 158, 160, 161, 162, 163, 169, 172, 174 microfibres, 196 microporous, 73, 74 microwaves, 122, 139, 143, 146 migrations, 13 mildew, 76, 78, 156, 161 military, 30, 36, 108, 111, 163, 166, 168 milk, 30, 158 mill, xiii, 7, 106, 112 mineralisation, 106 minerals, 13, 66, 178, 179 mining, 19, 172, 179 mites, 37, 166 mitins, 76 mobility, 167 modesty, 12 modification, 66, 71, 139, 145, 146, 197 modifier, 192 moiré, 69, 70

Index moisture, 25, 26, 46, 49, 54, 58, 63, 69, 70, 71, 72, 73, 94, 110, 115, 117, 118, 131, 139, 142, 144, 145, 157, 161, 162, 164, 167, 169, 171, 172, 174, 194 moisture content, 26, 46, 49, 142, 144, 162 molecular, 32, 44, 73, 79, 91, 116, 117, 120, 121, 122, 129, 139, 142, 145, 146, 200 molecular bonds, 44, 117 molybdenum, 150 money, xiii, 13, 56, 57, 98, 101, 104, 111, 180, 181, 201 monitoring, 105, 111 mooring, 96, 128, 173 mordants, 84 mothproofing, 108, 156 moths, 76, 155, 156, 163, 174 motor, 95, 105, 170 motorway, 172 mould, 49, 78, 156, 160, 161, 163 moulding, 202 moving staircase, 128 mulberry leaves, 29, 30 mule, 54 mutations, 10, 104 natural, 3, 4, 7, 8, 9, 10, 11, 15, 19, 21, 23, 24, 25, 31, 34, 36, 43, 44, 63, 67, 81, 82, 87, 94, 100, 103, 110, 115, 117, 120, 121, 122, 123, 137, 145, 150, 154, 161, 164, 171, 180, 191, 200 natural gas, 19 nautical, 94 necessities, 2, 12 needle-punching, 61, 66, 95, 108, 173, 202 needles, 18, 66, 126, 168 neps, 25 net-making, 61, 65 neutralisation, 10, 106, 108, 153, 162, 169 neutrinos, 122 nickel, 44, 96, 106, 121 nightwear, 163 nitrogen, 2, 80, 81, 118, 146, 147, 150, 157, 196, 198

219

nitrous oxide, 85 noise, 15, 48, 53, 54, 55, 56, 57, 62, 95, 102, 179, 181, 196 non-ferrous metals, 18 non-silicate, 189 nonwovens, 53, 61, 65, 93, 108, 142, 173, 194, 196, 202 nuclear, 20, 21, 104, 122, 166, 168 nutrition, 4, 5 nylon, 95, 110, 129, 154, 157, 158, 160, 162, 194, 201, 202, 203 obscures, 53 ocean, 1, 181 odour, 20, 37, 103, 156, 157, 158, 191 oil, 3, 13, 14, 18, 19, 20, 32, 34, 50, 53, 54, 72, 73, 75, 80, 84, 96, 98, 117, 134, 147, 155, 162, 163, 166, 170, 173, 179 oilskin, 73 olefin, 154, 162 oleophilic, 80 oligomers, 198 open structure, 140 open-end, 54, 187 opening, xv, 25, 49, 52, 54, 55, 65, 70, 80, 117, 126, 131, 140, 143, 145, 173, 174, 175, 179, 187 operating theatre, 11, 74, 167, 169 operation, 3, 11, 16, 19, 22, 25, 32, 34, 40, 42, 53, 54, 56, 58, 62, 63, 67, 70, 71, 74, 84, 87, 88, 104, 105, 108, 126, 127, 135, 143, 153, 170, 173, 174, 175, 187, 189, 191, 192, 200, 202 operative, 142, 144, 163 optical, 17, 46, 59, 92, 119, 120, 121, 197 optimisation, 106, 200 optimum, 4, 12, 24, 25, 26, 43, 44, 46, 63, 76, 95, 107, 172, 173, 174, 175, 183, 192, 198, 200 ores, 34, 66, 135 organdy, 153 organic, 15, 37, 40, 49, 76, 78, 93, 100, 101, 104, 106, 110, 150, 152, 154, 155, 187, 189, 198, 200, 201 organisms, 1, 2, 3, 7, 10, 132, 194 organofluorochemicals, 80 organohalides, 110, 198

220

Index

orientation, 192 orthopaedic, 195 oscillation, 120, 170 osmosis, 106 osmotic, 170 outdoor, 92, 131, 132, 140, 154, 165 overalls, 168 overfeed, 71 overheating, 33, 42, 170 overloading, 4, 178 oxalic acid, 27 oxidation, 44, 117, 131, 150, 201, 202 oxidative, 46, 72, 191, 198 oxidative bleaching, 46 oxides, 34, 35, 81, 100, 150 oxidising, 33, 44, 46, 152 oxygen, 2, 4, 14, 16, 58, 59, 82, 84, 93, 110, 117, 118, 121, 131, 146, 147, 178, 189, 194, 198 ozonation, 46, 100, 106, 197, 198 packaging, 11, 30, 58, 81, 99, 155 padding, 72 pain, 55 paint, 118, 154 papain, 43 paper, 15, 32, 34, 36, 79, 82, 87, 88, 94, 100, 101, 166, 168, 169, 170, 194, 200 parachutes, 12, 96 paraffins, 72, 86, 150 particles, 6, 14, 15, 18, 53, 57, 58, 104, 118, 122, 128, 170 paste, 81, 86, 87 patterns, 164, 172 peat, 157 pectin, 189, 190 pectinase, 183 PEEK, 196 penalties, 102, 105, 111, 180 pendulucata, 172 penetration, 82, 127, 139, 152, 168, 173, 190, 192 peracetic, 189 perchloroethylene, 48, 99 permanence, 87 permanent press, 145 permanganate, 153 permeability, 73, 94, 95, 108, 168, 171, 172, 174, 194

peroxide, 44, 46, 100, 120, 153, 159, 187, 189, 191, 197, 198, 201, 202 peroxyacids, 44 perspiration, 72, 73, 74, 157, 162, 167, 175 pesticides, 30, 169, 189, 197 pests, 24, 25, 31, 37 petrol, 49 pH, 27, 44, 46, 107, 183, 197, 201 phenols, 96, 106 phosphates, 37, 43, 93, 201 phosphorus, 80, 146, 147, 150, 157, 198 photocatalysis, 106 photofading, 121 photon, 119, 120 photoyellowing, 189 physical, xiii, xiv, 15, 17, 26, 46, 56, 86, 118, 126, 167 picking, 25 piece dyeing, 86, 87 pigments, 44, 86, 99, 106 pile, 67 pilling, 127 pin feed, 127 planet, xiii, xiv, xv, 1, 2, 4, 6, 8, 9, 10, 13, 14, 19, 21, 24, 26, 27, 31, 32, 36, 37, 49, 62, 63, 66, 67, 72, 78, 87, 88, 91, 93, 98, 103, 104, 105, 111, 112, 117, 120, 122, 130, 135, 136, 137, 150, 178, 180, 181, 182, 196, 201 planetary loading, 82, 191 planetary stability, 9 plants, xiii, 2, 3, 4, 5, 6, 7, 10, 14, 16, 19, 20, 21, 23, 24, 25, 26, 29, 30, 37, 40, 43, 48, 51, 52, 56, 57, 58, 59, 71, 75, 81, 93, 102, 105, 132, 169, 170, 172, 196, 198, 200 plasma, 80, 82, 85, 191, 192 plastics, 59, 88, 92, 96, 162, 163, 167, 168, 171, 173, 174, 196 pockets, 22, 170 poisoning, 3, 6, 16, 19, 30, 91, 104, 169, 171 police, 104, 168 pollution, xiii, xiv, 3, 4, 5, 6, 14, 15, 16, 18, 19, 20, 22, 30, 32, 34, 43, 49, 53, 56, 62, 63, 71, 72, 81, 82, 84, 85, 86, 87, 90, 91, 92, 93, 96, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107,

Index 108, 109, 110, 111, 112, 118, 137, 141, 155, 173, 178, 179, 181, 183, 194, 96, 197, 201, 202 pollution permits, 111 polyacrylic, 63 polyamide, 166, 192 polycarboxylic, 80 polyester, 26, 34, 55, 74, 79, 85, 87, 95, 96, 108, 110, 154, 158, 162, 165, 169, 189, 191, 192, 197, 198, 200, 202 polyethylene, 168, 173 polyimide, 194 polylactic acid, 34 polymeric, 32, 33, 34, 65, 67, 74, 169, 170, 174 polymerisation, 32, 73, 85 polymers, 31, 32, 33, 34, 63, 66, 67, 72, 74, 108, 110, 123, 172, 202 polyolefins, 80, 117 polypropylene, 158, 172, 192, 202 polysilanes, 36 polytetrafluoroethylene (PTFE), 74, 94, 162 polyurethane, 95 polyvinyl, 63 population, xiii, 14, 15, 178, 179 pore, 36, 196 porosity, 164 ports, 172, 174 possessions, 10, 12, 13 powder coating, 202 power, 7, 15, 18, 19, 20, 21, 22, 30, 31, 57, 66, 70, 94, 104, 123, 146, 168, 180, 191, 196, 201 PPS, 196 precipitation, 202 prehistoric, 62, 163, 164 pressure, 62, 63, 65, 70, 72, 85, 86, 100, 102, 103, 105, 170, 191, 192 pretreatments, 26, 189 price, 61, 181 primary, 4, 90, 170, 173 printing, 15, 29, 72, 81, 84, 85, 86, 87, 106, 120, 127, 179 printing pastes, 87 problems, xiv, 7, 8, 14, 15, 16, 18, 19, 25, 34, 35, 44, 49, 53, 54, 55, 56, 58, 59, 64, 75, 81, 82, 84, 85, 86, 87, 90, 92,

221

99, 100, 101, 106, 109, 111, 118, 143, 150, 156, 157, 173, 179, 181, 192, 196 process, xiv, 3, 6, 8, 10, 11, 20, 21, 22, 24, 25, 26, 27, 30, 35, 40, 42, 43, 44, 46, 48, 49, 52, 53, 54, 57, 61, 62, 63, 64, 65, 66, 67, 70, 71, 73, 74, 75, 76, 79, 84, 85, 86, 87, 91, 94, 96, 100, 106, 107, 108, 109, 110, 111, 112, 115, 116, 117, 118, 120, 122, 124, 125, 126, 127, 131, 134, 140, 141, 142, 146, 149, 156, 157, 173, 183, 189, 190, 191, 192, 197, 201, 202 processing, 25, 27, 30, 32, 42, 48, 53, 63, 68, 69, 71, 72, 78, 90, 99, 101, 106, 108, 111, 136, 140, 158, 169, 170, 192, 200 Procion Blue MX-2R, 198 production, xiv, 14, 15, 16, 18, 19, 20, 21, 22, 23, 25, 26, 27, 30, 31, 32, 33, 34, 35, 36, 37, 40, 42, 44, 48, 49, 51, 53, 54, 55, 57, 58, 59, 61, 62, 63, 65, 66, 67, 72, 74, 75, 79, 81, 82, 84, 88, 90, 91, 92, 95, 96, 98, 100, 101, 103, 104, 105, 107, 110, 112, 115, 116, 119, 122, 123, 126, 134, 135, 136, 140, 143, 144, 145, 149, 152, 153, 169, 178, 179, 180, 181, 183, 189, 196, 198, 201 products, 15, 18, 31, 37, 40, 59, 74, 198 profits, 57, 99, 111, 180 prolonging life, 14 properties, 16, 17, 18, 26, 27, 31, 32, 34, 35, 36, 37, 40, 44, 46, 49, 54, 72, 74, 75, 99, 115, 116, 118, 122, 128, 130, 133, 147, 158, 159, 164, 165, 171, 172, 174, 179, 183, 190, 191, 192, 194 protease, 46 protection, xiii, 2, 3, 4, 10, 11, 12, 13, 16, 18, 30, 36, 48, 56, 69, 72, 73, 76, 78, 85, 86, 88, 90, 91, 94, 95, 96, 99, 101, 102, 104, 105, 110, 117, 118, 132, 134, 137, 147, 152, 155, 156, 158, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 175, 180, 181, 194, 197 protective clothing, 166, 167, 168 protective coverings, 165

222

Index

proteins, 30, 44, 76, 153, 156 PTFE, 74, 94, 162 pulp, 110 pumice, 200 pure water, 4 purification, 34, 106, 170, 200 PVA, 190 PVC, 80, 174, 202 pyrolysis, 36 quality, 4, 13, 24, 25, 26, 29, 30, 31, 53, 54, 56, 59, 90, 99, 103, 106, 130, 144, 153, 189, 190, 191, 200, 201 quaternary ammonium, 75, 93, 159, 163, 194 quilted, 108 quotas, 111 radiant, 146, 167 radiation, 7, 10, 20, 21, 76, 78, 96, 100, 104, 115, 119, 120, 121, 122, 123, 129, 131, 132, 142, 146, 150, 159, 161, 164, 165, 167, 168, 172, 174, 181, 196, 198, 201 radio, 46, 122 radioactive, 7, 20, 21, 104, 123, 170 radio-frequency, 46 radiometers, 166 railway, 172 rain, 10, 42, 72, 128, 131, 132, 154, 155 raincoat, 73 raising, 69, 70, 130, 196 ramie, 43 random, 65, 202 raw materials, xiii, 2, 4, 18, 23, 32, 33, 51, 57, 65, 66, 108, 109, 135, 136, 145, 164, 183, 203 rayon, 110, 158 rays, 10, 120, 122, 123, 164, 165 reactive, 84, 107, 118, 121, 191, 192, 197, 198 reactive dyes, 84, 121, 200 reactors, 168 reagents, 44, 71, 72, 73, 78, 79, 84, 103, 112, 152, 153, 155, 162, 189 recondensation, 143 recovery, 36, 48, 71, 83, 91, 102, 107, 149, 202

recycling, 32, 34, 48, 54, 63, 67, 82, 91, 92, 93, 99, 100, 101, 106, 107, 108, 181, 189, 191, 196, 201, 202 reddening, 166 reducing, 18, 33, 42, 43, 44, 48, 62, 82, 84, 87, 99, 101, 102, 107, 108, 111, 141, 156, 170 reeling, 29, 30, 200 refining, 34 reflectance, 49 regain, 117, 142 regeneration, 31, 33, 42, 100, 108, 110, 158, 195 regulations, 99, 100, 101, 102, 106, 166, 169, 174, 191 reinforcement, 74, 94, 172, 174, 202 rejection, 66, 74, 84, 118 relative humidity, 30, 54, 117, 143, 162 relaxation, 125, 172 removal, 2, 40, 42, 43, 46, 59, 93, 103, 107, 118, 145, 154, 169, 189, 190, 191, 197, 198, 200, 201, 202 repair, 62, 169, 172, 195 repellency, 78, 84, 163 replacement organs, 14 report, 43, 53, 95, 99, 106, 108, 150, 160, 169, 198, 201 reprocessing, 20, 108, 202 research, 34, 37, 96, 99, 103, 106, 109, 141, 150, 156, 164, 167, 189 reservoirs, 172 residues, 7, 40, 44, 112, 149, 179, 198 resins, 15, 71, 75, 76, 78, 79, 86, 87, 94, 162, 200, 202 resist, 35, 37, 86, 87, 92, 118, 147, 153, 155, 167, 174, 175, 195 resistance, 18, 36, 72, 73, 75, 76, 78, 80, 84, 94, 95, 122, 125, 127, 129, 147, 155, 164, 166, 168, 171, 172, 174, 175, 189, 194 resistant, 35, 36, 37, 72, 73, 75, 76, 80, 96, 133, 147, 155, 160, 161, 162, 163, 166, 167, 170, 175, 179, 190, 198 resonance, 120 resource depletion, xiv, 107, 178 resources, 11, 13, 14, 94, 178, 179, 202 restrictions, 180 retailers, 92

Index retardant, 81, 144, 146, 147, 149, 150, 166 retting, 26, 27 reuse, 106, 166, 194, 197, 198, 200, 201, 202 RF, 48 rigidity, 18, 108, 190 ring, 54, 128, 187 rinsing, 106, 194 risk assessment, 169 risks, 4, 21, 33, 61, 74, 75, 78, 80, 85, 86, 96, 101, 105, 132, 140, 143, 147, 150, 153, 154, 164, 167, 168, 169, 202 rivers, xiii, 10, 15, 20, 21, 43, 90, 106, 174, 181 roads, 15, 51, 55, 96, 128, 133, 154, 172, 181 rollers, 54, 58, 72, 86, 126, 127 rolling, 127 roofing, 95, 128, 132, 155 ropes, 11, 54, 96, 128, 129, 132 rot, 145, 158, 163, 198 rotor-spun, 54, 190 rotproofing, 78 rotting, 75, 157, 158, 162, 163 roughening, 152 rovings, 54 rubbish, xiii, 149 rusting, 118 s. aureus, 158 sacking, 132 safety, 22, 33, 37, 44, 95, 99, 100, 102, 104, 106, 129, 130, 158, 163, 167, 168, 169, 191 sails, 13, 96, 128, 132, 154 saline, 155 salts, 76, 78, 112, 118, 132, 152, 154 scanning electron microscopy, 159, 190, 192 scission, 116, 117, 125, 145 scorching, 142, 144 scouring, 42, 43, 48, 63, 75, 106, 140, 153, 179, 183, 187, 189, 190, 191, 200 scrap, 70, 118, 144 screen, 1, 86, 164, 166 sea, 12, 18, 21, 134, 172, 173

223

Sea Island, 24 seat, 12, 13, 95, 96 secondary, 64, 90, 110, 134, 136, 150, 173 second-hand, 92, 108 sedimentation, 174, 200 seed fragments, 25 seed hairs, 23, 25, 26 seeds, 23, 25, 26, 59 separation, 26, 189, 196, 202 service, 13, 92, 96, 98, 115, 123, 130, 175, 181 set, xiv, 27, 31, 32, 37, 40, 58, 62, 67, 79, 102, 115, 120, 145, 152, 154, 163, 175 settling, 58, 200 sewing, 35, 66, 91, 136 shades, 24, 133, 164 shafts, 18, 118 shape, 12, 18, 30, 78, 96, 117, 120, 127 shear, 124, 125, 126, 128 shearing, 31, 40, 69, 70, 75 sheep, 2, 4, 31, 40, 156 sheep dip, 31 sheeting, 172 shelter, 4, 7, 26 shipment, 88 shipping, 22, 51, 87, 88, 103 shirts, 2, 100 shock, 147, 163 shoddiness, 180 shores, 173, 181 short fibres, 25, 54 showers, 72, 73 shred, 146 shrinkage, 72, 95, 145, 162, 163 shrinkproofing, 69, 71, 179 shuttle, 62 sick building, 94 sickness, 6, 20 side-chains, 116, 117, 125, 139, 145 sifting, 200 silica, 34, 189 silicate, 189 silicon carbide, 36 silicone, 80, 95, 119 silk, 23, 27, 30, 32, 38, 42, 43, 44, 70, 71, 108, 121, 144, 153, 157, 161, 162, 168, 190, 195, 200

224

Index

silkworms, 4, 27, 30 silver, 160 sink, 158, 173 sizing, 1, 6, 11, 12, 16, 18, 23, 37, 54, 57, 58, 61, 62, 63, 67, 72, 73, 76, 155, 156, 171, 190, 191, 192, 196, 201 skein, 42 skin, 6, 7, 42, 44, 81, 118, 127, 152, 156, 164, 166, 169, 195 slag heaps, 35 sleeping bags, 96 slivers, 40, 54 sludge, 107, 200 slurry, 196 ‘smart’ textile, 140 smog, 19 smoke, xiii, 80, 81, 103, 147, 170 socks, 91, 158 sodium carbonate, 43 carboxymethylcellulose, 189 dodecyl sulphate, 27 metasilicate, 43 sulphate, 198 sofa, 128 softening, 74, 75, 84, 92, 93, 119, 131, 144, 163 softness, 43, 56, 66, 95, 165, 183, 187, 189 soil, 5, 6, 7, 10, 15, 24, 25, 34, 78, 118, 128, 132, 154, 157, 171, 173, 174, 181 soiling, 92, 118 soilless culture, 198 solar, 7, 10, 21, 120, 122, 164, 165, 166, 196 solar radiation, 7, 10 solids, 7, 16, 17, 32, 33, 57, 67, 87, 109, 131, 155, 169, 170, 189, 200, 202 solution dyeing, 84 solvents, 31, 32, 33, 42, 48, 63, 80, 85, 93, 100, 118, 131, 133, 143, 152, 154, 155, 162, 171, 187, 189, 192, 196, 200, 202 sorption, 107 sorting, 202 sound, 24, 55, 56, 62, 72, 80, 102, 119, 170, 189 sound pressure level, 62, 170 space, 9, 13, 15, 33, 36, 66, 79, 94, 95,

96, 111, 117, 128, 134, 144, 169, 170, 180 space suits, 13 spacecraft, 135 spacing, 174 species, xiv, 4, 5, 6, 9, 10, 13, 14, 15, 16, 21, 24, 36, 49, 58, 59, 63, 64, 72, 78, 92, 93, 122, 134, 150, 181 spectra, 198 spectrometry, 192 spectrophotometer, 166, 198 spectroscopic, 201 spectrum, 56, 78, 119, 120, 121, 122, 166 SPF (solar protection factor), 164, 166 spiders, 4, 30, 168 spills, 19, 158, 173 spindle, 126 spinnability, 26, 59 spinneret, 30, 32, 33, 34 spinning, xiii, 2, 12, 18, 29, 31, 32, 33, 36, 54, 63, 85, 126, 179, 190, 202 splashes, 167 splitting, 200 spoilage, 118 spores, 155 sporting, 96, 128, 131, 154, 157, 166, 196 spunbonding, 65 spunlacing, 65 squeegee, 86 stability, 9, 10, 48, 54, 67, 75, 95, 122, 154, 171, 178, 181, 189 stabs, 168 stack, 103, 112 staining, 46, 75, 78, 80, 93, 118, 154, 156, 159, 160, 162, 163, 174, 175 stalks, 26 standards, 12, 69, 72, 99, 100, 101, 102, 103, 104, 130, 155, 166, 167, 168, 182, 195 staple, 167 starch, 7, 63, 75, 86, 190, 191, 202 starvation, 4 static electricity, 7, 159, 163 statistics, 135 status, 8, 12 steady-state, 142 steam, 21, 30, 42, 64, 69, 71, 87, 100, 102, 139, 142, 143, 189, 200, 203

Index steel, 18, 21, 94, 168 stem, 17, 26 stenter, 102, 141, 143, 144 stents, 195 sterilising, 194 stickiness, 25, 49 stiffness, 63, 74, 75, 108, 156, 172, 190 stitch-knitting, 61 storage, 20, 25, 49, 62, 116, 128, 135, 150, 156, 161, 162, 173, 174, 180 storms, 7, 72, 128, 164, 173 strands, 11, 17, 32, 126 streams, 15, 20, 104, 106, 181 strength, 11, 17, 30, 43, 46, 49, 63, 70, 71, 108, 120, 121, 143, 156, 171, 174, 187, 189, 190, 192 stress, xiii, 46, 58, 71, 78, 94, 119, 123, 124, 125, 126, 127, 128, 130, 131, 133, 166, 167, 172, 178, 181, 192 stresses, 29, 75, 101, 115, 123, 124, 125, 127, 130, 137, 172, 174, 175, 190 structural engineering, 30 structure, 7, 10, 11, 14, 15, 26, 35, 36, 54, 56, 65, 73, 78, 79, 91, 94, 95, 116, 117, 118, 120, 121, 122, 123, 125, 126, 127, 128, 139, 140, 142, 145, 146, 156, 164, 167, 171, 173, 174, 175, 187, 200 sublimation, 87 submarine, 196 substandard, 66 substantive, 84 sugar content, 49 suint, 43 sulphonation, 78, 121 sulphonyl azide, 192 sulphur, 49, 110, 147, 150, 157, 191, 201 sulphur dioxide, 110 sulphur dyes, 84 sulphuric acid, 46, 153 sun, 9, 10, 14, 22, 119, 122, 164, 165, 166 sunblinds, 168 sunburn, 164, 169 sunlight, 24, 42, 76, 120, 129, 131, 140, 156, 164, 189 supercritical, 85, 192, 202 superheated, 64, 143 surfaces, 11, 13, 14, 18, 20, 21, 24, 34,

225

35, 37, 57, 58, 61, 67, 70, 72, 74, 75, 79, 82, 85, 86, 87, 93, 96, 117, 118, 120, 122, 124, 125, 126, 127, 128, 129, 131, 140, 142, 152, 153, 154, 155, 156, 158, 159, 162, 169, 170, 171, 172, 173, 174, 187, 190, 192, 200 surfactants, 183, 200 surgeon, 167 surgical, 11, 74, 95, 96, 167, 169, 180, 194 survival, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 37, 78, 137, 147, 157, 163, 164, 178, 180, 181, 182 sutures, 30 sweating, 131 swelling, 85, 117, 118, 202 swimming pool, 154 symptom, 145 synthetic, 23, 31, 34, 42, 63, 69, 70, 80, 81, 82, 84, 87, 97, 100, 110, 114, 154, 158, 161, 162, 164, 168, 179 table linens, 93, 162 tanker, 98 tannery, 174 tarpaulins, 13, 96, 128, 132, 152 tartaric acid, 43 tatting, 61, 65 tax, 99, 101, 102 TC, 198 TDOP, 147 tea towels, 133 tearing, 121, 124, 129 technical, xv, 74, 94, 95, 180 technical textiles, 94 technology, 11, 24, 26, 32, 35, 65, 74, 92, 100, 103, 108, 143, 163, 191, 198, 200, 202 temperature, 4, 5, 26, 27, 30, 34, 33, 35, 36, 55, 64, 73, 75, 79, 82, 84, 85, 87, 93, 96, 106, 120, 131, 133, 140, 141, 142, 143, 144, 146, 147, 152, 161, 162, 183, 191, 192, 196, 197, 198, 202 tenacity, 27, 36 tendering, 157 tensile, 67, 71, 94, 108, 121, 123, 124, 125, 126, 127, 128, 129, 156, 171, 187, 189, 190, 192

226

Index

tension, 32, 175, 190 tenter, 71, 127, 141, 144, 146 tents, 13, 94, 95, 96, 128, 132, 154, 157, 196 test, 56, 71, 95, 107, 129, 147, 158, 164, 167, 169, 171, 172, 194, 197 testing, 59, 128, 129, 166, 169, 171, 172, 189, 194 tetra acetyl ethylene diamine (TAED), 46 tetrafluoride, 82 tex, 27, 74 textile industry, xiii, xiv, 8, 16, 22, 43, 49, 76, 81, 100, 108, 136, 140, 145, 178, 179, 180, 181, 182 textile production, xiv, 8, 12, 14, 17, 18, 19, 31, 51, 58, 98, 106, 118, 134, 136, 158, 178, 181, 202 textile products, 11, 12, 13, 37, 117, 137, 139, 140, 147, 150, 180, 181 texturing, 54, 55, 96 the earth, xiv, 1, 8, 9, 14, 17, 21, 99, 104, 120, 157 thermal, 17, 18, 33, 35, 36, 64, 66, 70, 72, 73, 92, 95, 96, 108, 123, 131, 133, 134, 139, 140, 142, 145, 146, 147, 149, 150, 164, 165, 167, 175, 180 thermogravimetric analysis, 108 thermoplastic, 34, 75, 196, 202 thickeners, 72, 81, 86 thickness, 7, 108, 123, 143, 195 thinners, 154 threads, 30, 35, 156, 195 TIC, 198 tidal, 21, 128, 155, 173 tight, 173, 174 tile cement, 154 tine, 54 tissue, 11, 195, 204 titanium, 37, 100, 106 titanium dioxide, 37, 198 TOC, 197, 198 tools, 11, 122 tops, 54, 187 tornados, 16 torsion, 123, 125, 126, 128 touch, 66, 145, 163 towels, 93, 133, 194 toxic, 2, 5, 6, 7, 16, 19, 29, 30, 33, 34, 37,

43, 49, 72, 73, 76, 78, 79, 80, 81, 84, 93, 98, 99, 103, 104, 105, 106, 110, 134, 144, 147, 150, 158, 159, 165, 168, 170, 171, 172, 174, 179, 181, 189, 196, 200 trace impurities, 110 trade, 13, 105, 111, 179 traffic, 55, 95, 172 transfer, 86, 87, 95, 140, 142, 157, 167, 169, 170 transmission, 53, 56, 108, 157, 165, 166, 171 transmittance, 166 transplanted, 194 transportation, 13, 37, 48, 49, 50, 51, 62, 66, 88, 92, 93, 96, 103, 127, 128, 155, 181 trash, 25, 40, 42, 53, 59, 103 travel, 12, 13, 51, 62, 143, 144 treatments, 15, 17, 24, 26, 27, 31, 43, 46, 58, 68, 69, 70, 71, 72, 73, 74, 75, 76, 78, 79, 80, 81, 82, 84, 85, 87, 100, 101, 102, 104, 106, 107, 108, 127, 130, 133, 146, 147, 153, 154, 158, 159, 163, 174, 179, 181, 183, 187, 190, 191, 192, 194, 197, 198, 200, 201, 202 tributylin, 99 tufting, 52, 61, 67, 156 turbines, 20, 21 tussah silk, 29 twisting, xiii, 11, 12, 54, 124, 125, 126, 145, 149, 171, 174, 175 tyre, 13, 96, 128, 133, 180 tyrosine, 71 ultrafiltration, 63, 106, 191, 195, 196, 201 ultrasonic, 43, 46, 67, 72, 122, 139, 146, 192 ultraviolet, 10, 76, 78, 100, 119, 120, 121, 129, 131, 150, 159, 161, 164, 165, 166, 167, 171, 172, 174, 175, 198, 201 underarm, 157, 167 undersea, 96 underwear, 2, 73, 158 unevenness, 201 uniform, 11, 12, 13, 33, 36, 52, 70, 108, 164, 183

Index uniformity, 30, 102, 189 unwinding, 27, 30 upholstery, 90, 91, 96, 129, 132, 152, 163 urea, 71, 79 urea-formaldehyde, 71, 79 urine, 157 vacuum, 202 vapour, 33, 72, 73, 87, 94, 117, 131, 169, 171, 174, 194 varnish, 118, 154 vat, 106, 198 vat dyes, 84 vegetable, 1, 24, 40, 43, 93, 189 vegetation, 181 vehicles, 12, 49, 51, 95, 96, 105, 128, 132, 134, 170 ventilation, 167, 169 vessels, 173 vibration, 56, 78, 122 vinegar, 154 vinyl, 75, 79, 80 viscose, 26, 110, 153, 200 viscosity, 58, 86, 94, 202 visible, 121, 132, 145, 179, 198, 201 visual, 15, 102, 159, 171, 178 volume, 55, 106, 194 wall coverings, 163 wall hangings, 96 war, 10, 72, 98, 147, 166, 169, 179 warp, 62, 164, 190 washfastness, 192, 194 washing, 10, 42, 43, 48, 69, 70, 71, 80, 81, 84, 86, 87, 92, 93, 118, 131, 140, 145, 150, 153, 154, 156, 160, 169, 171, 173, 179, 191, 194, 200, 201 waste, 2, 3, 4, 18, 19, 20, 21, 22, 30, 32, 33, 48, 53, 54, 57, 61, 62, 64, 66, 67, 70, 71, 75, 78, 80, 81, 82, 84, 91, 96, 98, 99, 101, 102, 104, 106, 107, 108, 110, 143, 144, 145, 147, 171, 174, 179, 189, 190, 196, 197, 198, 200, 201, 202 water, xiv, 2, 3, 4, 6, 7, 9, 13, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 30, 31, 34, 42, 43, 44, 48, 54, 63, 64, 65, 69, 71, 72, 73, 74, 75, 78, 80, 81, 82, 84, 85, 86, 90, 92, 93, 99, 100, 101, 102,

227

106, 107, 108, 109, 112, 113, 117, 118, 131, 132, 133, 141, 142, 143, 145, 147, 155, 156, 157, 158, 161, 163, 164, 166, 167, 168, 170, 172, 173, 174, 178, 179, 181, 183, 189, 194, 196, 197, 198, 200, 201, 205 water courses, 181, 174 waterlogging, 172 watermarking, 70, 118 waterproof, 74, 161, 162, 172, 175 water-resistant, 74, 80, 179 wave, 128, 170, 173 wavelength, 119, 165 wax, 40, 72, 75 weakening, 25, 126, 157, 160, 175 wealth, 8, 10, 12, 13, 91 weapons, 11, 12, 98 wear, 7, 13, 56, 92, 118, 121, 128, 129, 162, 163, 165, 167, 170, 172, 194 weather, 10, 15, 94, 95, 152, 163, 166, 169 weathering, 22, 37, 42, 131, 174 weaving, xiii, 12, 61, 62, 63, 70, 94, 95, 126, 128, 130, 142, 164, 174, 190, 195, 196, 205 webbing, 12, 96 webs, 196 weed-killers, 132 weeds, 40, 93 weft, 62 weight, 18, 43, 95, 96, 108, 109, 147, 183, 194 welders, 167 wet, 31, 33, 42, 72, 99, 101, 106, 142, 145, 190, 192 wet spinning, 31, 42, 190 wet-bulb temperature, 142 wetting, 72, 118, 183, 190 white rot fungus, 198 whitefly, 24 whitening, 43, 44, 46, 183, 187, 189, 197, 200 whorls, 12 wicking, 142 wild silk, 29 wind, 21, 22, 24, 54, 62, 70, 94, 95, 103, 126, 128, 131, 132 windy, 15, 175 wines, 154

228

Index

wood, 15, 32, 36, 96, 107, 203 wool, 2, 23, 31, 35, 40, 43, 44, 46, 58, 63, 65, 69, 72, 75, 76, 82, 94, 97, 101, 110, 114, 120, 153, 156, 157, 161, 162, 163, 166, 175, 187, 191, 192, 200, 203, 205 woollen, 59, 190 workers, 7, 13, 18, 27, 29, 33, 34, 56, 57, 58, 62, 64, 96, 101, 102, 103, 110, 167, 168, 189, 198 working conditions, 29 workplace, 132 world, xiii, 10, 12, 13, 14, 18, 19, 20, 23, 31, 43, 49, 58, 78, 91, 92, 103, 104, 135, 136, 173, 178, 180, 191 worn, 2, 13, 56, 152, 156, 158, 181 worsted, 53 wound, 11, 30, 62, 63, 126, 164, 195

X-ray diffraction, 123 X-rays, 122, 123, 146, 192 yarns, 12, 17, 18, 26, 37, 40, 42, 53, 54, 59, 61, 62, 63, 65, 66, 67, 71, 80, 91, 108, 126, 127, 140, 142, 144, 160, 167, 171, 174, 179, 180, 187, 189, 190, 200 yellowing, 26, 48, 75, 79, 120, 145 yield, 24, 25, 34, 108, 120, 149, 183, 189, 191 zeolite, 189 zinc, 37, 100, 106 α-rays, 122, 123 β-rays, 122, 123 γ-rays, 122, 123