Ageing of Rubber - Accelerated Weathering and Ozone Test Results

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O3

Ageing of Rubber

Accelerated Weathering and Ozone Test Results

R.P. Brown, T. Butler and S.W. Hawley

Europe’s leading independent plastics and rubber specialists

Ageing of Rubber Accelerated Weathering and Ozone Test Results

R.P. Brown, T. Butler and S.W. Hawley Rapra Technology Limited

This report is an output from the Weathering of Elastomers and Sealants project which forms part of the UK government’s Department of Trade and Industry’s Degradation of Materials in Aggressive Environments Programme.

Rapra Technology Limited Shawbury, Shrewsbury, Shropshire SY4 NNR, United Kingdom Telephone: +44 (0)1939 250383 Fax: +44 (0)1939 251118 http://www.rapra.net

Practical Guide to Polyethylene

First Published in 2001 by

Rapra Technology Limited Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK

©Copyright 2001 Rapra Technology Limited

A catalogue record for this book is available from the British Library. ISBN: 978-1-85957-264-1 Every effort has been made to contact copyright holders of any material reproduced within the text and the authors and publishers apologise if any have been overlooked.

All rights reserved. Except as permitted under current legislation no part of this publication may be photocopied, reproduced or distributed in any form or by any means or stored in a database or retrieval system, without the prior permission from the copyright holder. The report is published in good faith, but on the basis that no responsibility or liability of any nature shall attach to Rapra Technology Limited arising out of or in connection with any utilisation in any form of any material contained herein

Typeset by Rapra Technology Limited Printed and bound by Lightning Source UK Ltd

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Contents 1. Introduction ...................................................................................................................... 1 2. Materials .......................................................................................................................... 1 2.1 Original Materials ..................................................................................................... 1 2.2 New Materials ........................................................................................................... 2 3. Preparation of Test Pieces ................................................................................................. 3 4. Physical Tests .................................................................................................................... 3 5. Exposure of Test Pieces ..................................................................................................... 3 5.1 Weathering ................................................................................................................. 3 5.2 Ozone Exposure......................................................................................................... 4 6. Weathering Results (Appendix 2) ..................................................................................... 4 6.1 Presentation ............................................................................................................... 4 6.2 Uncertainty ................................................................................................................ 5 6.3 Interpretation of results ............................................................................................. 5 7. Ozone Results (Appendix 3) ............................................................................................. 6 8. Discussion ......................................................................................................................... 6 8.1 Weathering ................................................................................................................. 6 8.1.1 General ............................................................................................................. 6 8.1.2 Hardness .......................................................................................................... 7 8.1.3 Modulus ........................................................................................................... 8 8.1.4 Tensile Strength ................................................................................................ 8 8.1.5 Elongation at Break .......................................................................................... 9 8.1.6 Effect of Temperature ....................................................................................... 9 8.2 Ozone ...................................................................................................................... 11 9. Conclusions .................................................................................................................... 12 References ........................................................................................................................... 12 Appendix 1 - Compound Details ......................................................................................... 13 Appendix 2 - Weathering Results ........................................................................................ 25 Compound A - Natural Rubber - Standard .................................................................... 27 Compound B - Natural Rubber - Good Ageing .............................................................. 31 Compound C - Natural Rubber - Mineral Filler Loaded ................................................ 35 Compound D - Natural Rubber - Mineral Filler (Heavy Loaded) .................................. 39

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Compound E - Styrene Butadiene Rubber - General Purpose ......................................... 43 Compound F - Styrene Butadiene Rubber - Good Ageing ............................................... 47 Compound G - Styrene Butadiene Rubber - General Purpose ......................................... 51 Compound H - Styrene Butadiene Rubber - Good Ageing .............................................. 55 Compound J - Butyl Rubber - General Purpose .............................................................. 59 Compound K - Butyl Rubber - Good Ageing .................................................................. 63 Compound L - Polychloroprene - General Purpose ........................................................ 67 Compound M - Polychloroprene - Natural Ageing ......................................................... 71 Compound N - Polychloroprene - Heat Ageing .............................................................. 75 Compound P - Nitrile Rubber - General Purpose ........................................................... 79 Compound R - Polychloroprene - Good Ageing ............................................................. 83 Compound S - Miscellaneous - Acrylate Rubber ............................................................ 87 Compound T - Miscellaneous - Chlorosulphonated Polyethylene .................................. 91 Compound W - Miscellaneous - Polysulphide Rubber .................................................... 95 Compound X - Miscellaneous - Silicone Rubber ............................................................ 99 New Compounds Compound N1 - FVMQ ............................................................................................... 103 Compound N2 - HNBR ............................................................................................... 107 Compound N3 - Epoxidised Natural ............................................................................ 111 Compound N4 - Chlorinated Polyethylene ................................................................... 115 Compound N5 - Fluorocarbon ..................................................................................... 119 Compound N6 - Exxpro ............................................................................................... 123 Compound N7 - Epichlorohydrin ................................................................................. 127 Compound N8 - EPDM ................................................................................................ 131 Compound N9 - EVA ................................................................................................... 135 Compound N10 - PU .................................................................................................... 139 Participant’s Compounds Compound P1 ............................................................................................................... 143 Compound P3 ............................................................................................................... 147 Compound P4 ............................................................................................................... 151 Compound P5 ............................................................................................................... 155 Compound P6 ............................................................................................................... 159 Compound P7 ............................................................................................................... 163 Compound P8 ............................................................................................................... 167 Compound P9 ............................................................................................................... 171 Compound P10 ............................................................................................................. 175 Appendix 3 - Ozone Results .............................................................................................. 181

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Ageing of Rubber - Accelerated Weathering and Ozone Test Results

1 INTRODUCTION A long-term natural ageing programme was started in 1958 when 19 rubber compounds were exposed at 3 locations. The final sets of test pieces were withdrawn in 1998 giving a total of 40 years of natural ageing. The results of the physical tests carried out at intervals over the 40 years have been published [1]. The 19 compounds were re-mixed in 1999–2000 in order that accelerated ageing tests could be carried out for direct comparison with the results from natural ageing. A total of 20 new compounds were also mixed to represent polymers not available in 1958 and to reflect changes in compounding practice. Ten of these materials were formulations directly nominated by industry covering materials of current interest to particular companies. The 39 materials were subjected to accelerated heat ageing for a series of times and temperatures, artificial weathering and exposure to ozone. This report details the results of the artificial weathering and ozone exposure tests and makes comparisons with the results after natural ageing. The accelerated heat ageing results will be published separately (Ageing of Rubber— Accelerated Heat Ageing Results).

2 MATERIALS The test pieces used in the programme were produced from compounds with the formulations given in Appendix 1. For reasons of confidentiality, the materials nominated by industry are only described by polymer type. As regards the original 19 materials, it is perhaps surprising that compounding has changed relatively little and most of the formulations are relevant today. The new compounds formulated by Rapra, with advice from the project Industry Steering Group, were selected as being the more commercially important of the many polymers and compounding ingredients introduced since the start of the project in 1958.

2.1 Original Materials Four natural rubber compounds were selected. Compound A was selected as it had been used at Rapra for many years as a standard material which loosely represented a tyre tread or high grade conveyor belt cover. Compound B has what became known as an efficient vulcanising system with no elemental sulphur, although the term had not then been coined. Compound C represents a fairly high rubber content, non-black filled material. The final natural rubber compound D was requested by the electrical side of the industry as a highly loaded, low grade insulation material and was said to exhibit good ageing properties in the dark. Compounds E and F are styrene butadiene rubbers (SBR) corresponding to A and B whilst G and H are oil extended versions. Compounds J and K were referred to as general purpose and good ageing butyl compounds, respectively. They represent the extremes of polymer available, with high and low unsaturation, respectively.

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The three polychoroprene compounds came from the polymer supplier and were labelled general purpose (L), natural ageing (M) and heat ageing (N). The two nitrile compounds were suggested by the main UK supplier at the time to represent a general purpose material (P) and a good ageing formulation (R). The remaining compounds were also suggested by the relevant suppliers as general purpose materials.

2.2 New Materials Compound N1 is a fluorosilicone-based on LS 2380U. The hydrogenated nitrile compound N2 is a formulation to give heat resistance. Compound N3 is an epoxidised natural rubber with low black loading used in an acoustic application. The chlorinated polyethylene, compound N4, represents a formulation for hose tube and cover material. Compound N5 is a 70 IRHD fluorocarbon-based material for seal applications. Compound N6 is an Exxpro material (isobutylene p-methylstyrene copolymer) described as general purpose. The epichlorohydrin material, compound N7, is also formulated for general purpose use. The sulphur cured ethylene propylene terpolymer (EPDM), compound N8, is a formulation typically used for radiator hose applications. Compound N9 is an ethylene vinyl acetate cable sheathing material. Compound N10 is a general purpose millable polyurethane. Compounds P1–P10 are materials submitted by industry participants: Compound P1

ethylene propylene copolymer

Compound P2

siloxane material

Compound P3

medium nitrile, carbon black filled with EV sulphur cure

Compound P4

nitrile, NF standard 0115/2

Compound P5

EPDM, NF standard 0115/1

Compound P6

Vamac G material, black filled with a Diak/DOTG cure system

Compound P7

W type polychloroprene with small amount of SBR, carbon black filled, sulphur/metal oxide cure

Compound P8

natural rubber

Compound P9

thermoplastic rubber—Santoprene 101 55 V185 from AES

Compound P10

nitrile

Compound P2 was not tested for weathering and ozone resistance because it was a special purpose cellular material.

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Ageing of Rubber - Accelerated Weathering and Ozone Test Results

3 PREPARATION OF TEST PIECES Batches of all 39 compounds were mixed. In most cases 2 batches were needed, which were blended. Standard 2 mm sheets were produced by compression moulding. The cure times used in 1958 for the original materials could not be derived from measurements in a curemeter as these instruments were only in the experimental stage. Hence, they were derived from a programme of curing for various times and measuring physical properties. The cure times for the new materials were derived from measurements on a Monsanto rheometer. The cure conditions arrived at are given in Appendix 1.

4 PHYSICAL TESTS Ideally, the same physical tests as used in the natural ageing programme would have been used to monitor changes but the volume of work that would have entailed was prohibitive. Hence, the following properties were selected for monitoring the artificial weathering exposures: • tensile strength, • elongation at break, • stress at 100% elongation, • stress at 300% elongation, and • hardness. These properties correspond to properties monitored in the natural ageing programme. It may be noted that for the heat ageing exposures, compression set and dynamic properties were also measured. Monitoring of the effects of ozone exposure was by observation of cracks using a x7 lens. Tests were carried out in general accordance with the current ISO methods [2–3]. For tensile properties, type 2 dumbbells were used, with 3 dumbbells being tested at each measurement point. Hardness measurements were made by taking 5 readings on one test piece. Ozone exposure test pieces were in the form of T50 dumbbells.

5 EXPOSURE OF TEST PIECES 5.1 Weathering Test pieces were exposed in QUV fluorescent tube apparatus using UVA 340A lamps with a black panel temperature of 45 °C and a cycle of 4 hours condensation and 4 hours dry (3 cycles per day) [4]. By agreement with the supplier of material P2, it was not tested for weathering resistance.

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Seven sets of 3 dumbbells and a piece of sheet for hardness measurements were exposed. Sets of test pieces were removed and tested at approximately 30 day intervals up to 6 months (leaving 1 set spare). Test pieces were conditioned for a minimum of 16 hours at 23 °C and 50% relative humidity prior to test.

5.2 Ozone Exposure Test pieces were strained to 5, 10, 15, 20 and 30%. After conditioning for 72 hours, they were exposed to ozone at 23 °C [5]. All materials were exposed to 50 pphm of ozone for up to 1 month. The exposure was repeated at 200 pphm of ozone but excluding those materials that had cracked to grade 3 most rapidly at 50 pphm (E, F, G, H, N3 and P3). By agreement with the supplier of material P2, it was not tested for ozone resistance. The test pieces were examined after nominally 2, 4, 8, 16 and 24 hours and daily thereafter and any cracking noted.

6 WEATHERING RESULTS (APPENDIX 2) 6.1 Presentation The results for each property after artificial weathering were plotted as a function of exposure time. The tensile properties are the mean of results on 3 test pieces and the hardness result is the median of 5 readings. A best fit line was then constructed by computer for each graph using proprietary software which selects from hundreds of functions. Hence, the function in each case was selected on an empirical basis and there is no a priori reason to suppose that the same function would be valid for extrapolations. Alternative functions might be considered preferable. The initial and 6 month values for each property were then read off the best fit lines. This means that these values are not necessarily the same as the initial and final plotted data points. This treatment gives no special weighting to the initial unaged data, nor to the final 6 month results. From the initial and final values, the differences and the differences expressed as percentage change have been tabulated. Values were generally read to three significant figures and, to avoid misleading rounding errors, the percentage changes are given to two significant figures. This does not imply accuracy to the number of figures recorded. Whenever possible, values are quoted for both 100% and 300% modulus. In some cases, values for 300% were not available for the longer exposure times. This necessitated the extrapolation of the best fit line through the 6 month point in order to produce a comparative percentage change value.

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Ageing of Rubber - Accelerated Weathering and Ozone Test Results

6.2 Uncertainty In order to make a realistic assessment of the significance of the results, it is necessary to make an estimation of the variability of the test results. An indication of variability is illustrated on the graphs by means of error bars. These were derived from standard deviations for repeatability taken mostly from precision statements in ASTM and ISO test method standards. The repeatability standard deviations were multiplied by 2 to give the 95% confidence intervals. It will be appreciated that these error bars simply give an idea of the degree of scatter which might generally be expected. Comment is made below on the uncertainty of estimates made by extrapolation of the results but no attempts at quantification have been made.

6.3 Interpretation of results A quick snapshot view of the changes which have taken place over 6 months exposure is given by Table 1 for each material. However, the figures giving change and percentage change need to be viewed in context with the level of the property measured and the uncertainty. For example, the 100% modulus figures are generally small so that a relatively minor change may appear as a large percentage change and the experimental uncertainty is large. The graphical presentation allows at least a subjective assessment to be made of the significance of the recorded changes. In most cases, a clear trend is apparent with little masking by scatter of results. It is appreciated that, in general, the change of property with time is not linear and, hence, it is not strictly correct to make predictions based on the change over 6 months. Using this simplified approach is justified on the grounds that: • the prime object of the artificial weathering trials was to obtain the order of magnitude of the effects of weathering in comparison to those from heat ageing, and • the uncertainties of subtracting the effect of heat alone and extrapolating to ambient weathering conditions are in any case very large. Estimates of the expected changes in properties over 6 months from exposure to a temperature of 45 °C were obtained by making Williams Landel Ferry (WLF) transforms of the accelerated ageing results reported separately. By subtraction of these figures from the weathering results, the effect due to light (and possibly moisture) over 6 months can be estimated. These effects are tabulated in Table 2 for each material. Missing figures are due to the raw data being insufficient or very highly variable. If an acceleration factor due to the higher irradiance in the weathering apparatus compared to natural sunlight is assumed, it is possible to estimate the effects of weathering at 23 °C under natural exposure to light. It is appreciated that such acceleration factors are generally regarded as invalid because of the variation in solar radiation and the differences in distributions of the wavelengths of the light. However, to give an estimate of the order of magnitude of change that might be expected from weathering, acceleration factors were derived from quoted irradiance

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and annual solar radiation figures. The factors derived for the UVA 340 lamps were Arizona 6.0, Florida 7.1 and London 14.0. Estimates for 10 years’ exposure in London are given in the same table, calculated from: C⋅

10 1 ⋅ 0.5 14

where C is the net change due to weathering after 6 months. The 10-year period is equivalent to only a relatively modest extrapolation of the 6 month exposure graphs but, because of the uncertainty in the acceleration factor, the figures can at best be considered as tentative.

7 OZONE RESULTS (APPENDIX 3) The times to first observed cracking (Grade 1 cracking) as a function of strain are given for results at 50 pphm and at 200 pphm, along with the times to reach Grade 3 cracking (Tables 1– 4). Compounds which did not crack have been omitted. Graphical representations of the times to first cracking are given in Figures 1 and 3 and of times to Grade 3 cracking in Figures 2 and 4. The times to first observed cracking were plotted as a function of strain and an exponential function fitted. Selected graphs are given in Figures 5–7. It is not sensible to attempt to interpret accelerated ozone exposure tests in terms of times to cracking under ambient conditions. Clearly, the best result is for there to be no cracking, and compounds which have not cracked after 1 month at 200 pphm can be considered totally resistant. Distinction between materials that have cracked can be made on the basis of the length of time to cracking at a given ozone concentration, the maximum strain without cracking and the severity of cracking. As an indication of performance in relation to service, a material passing a typical specification requiring no cracking after 7 days at 50 pphm and 20% strain would be expected to give at least 5 years’ service without cracks under typical ambient conditions.

8 DISCUSSION 8.1 Weathering 8.1.1 General Comment is made for each property on the trends seen during accelerated weathering, rather than attempting a detailed analysis of each compound property by property.

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Ageing of Rubber - Accelerated Weathering and Ozone Test Results

For the original 19 compounds, the trends are compared to the natural ageing results, always bearing in mind that they were in the absence of light. Then the estimated contributions due to temperature (obtained from accelerated heat ageing tests) and UV light are discussed, and comment made on the magnitude of the estimated net change due to weathering. Several overall observations can be made. Weathering and shelf or heat ageing differ because of the presence of UV light in the former, and it is perhaps not surprising that there are many observed differences in behaviour between the two. However, the direction of change is generally similar with only relatively few cases where there is total conflict. The traditional view has been that weathering, UV light in particular, has minor effect on rubbers. These results show that in many cases accelerated weathering produces quite large changes in properties. Adjusting the results for the effect of temperature often made a big difference to individual properties but overall the effects due to weathering were still found to be very significant. There are considerable differences in the magnitude of the response to weathering as measured by different properties, which illustrates the generally held view that preferably several relevant properties should be investigated in any exposure trial. The ranking of materials is not consistent across different properties which reinforces the need to consider more than one property when characterising or selecting materials. The natural rubber compounds C and D showed significant surface cracking (Appendix 2, Figures 1 and 2), which is illustrated in Figures 1 and 2. The pattern of cracks is reminiscent of ‘alligatoring’ which has been observed on polymeric roof membranes used in hot climates with high UV exposure and intermittent rainfall. This has been attributed to localised stresses due to wetting and drying coupled with degradation due to temperature and UV light. It is perhaps significant that these two compounds (especially D) have high loadings of calcium carbonate.

8.1.2 Hardness For all materials, there was either an increase in hardness or the hardness was very little changed over the six months. For the majority of compounds, the increase was less than 10% and for 15 compounds below 5%. Compounds D, N, T, W, P7 and P8 had increases above 10% with natural rubber D and Hypalon T above 20%. In many cases, there is a tendency for the rise in hardness to be more rapid at the beginning and then to plateau out. This is significant for compounds D, E, F, M, N, T, W, N10 and P10 with the effect being very large in the case of natural rubber D and Hypalon T. These were the two materials that showed the greatest total rise. One important implication of this is that linear extrapolation would be very misleading. It would be reasonable to suppose that the rapid increase was largely a surface effect.

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Compounds N2, N4, N9, P1 and P4 apparently exhibit slightly more complex behaviour with P1 and P4 possibly reducing in hardness towards the end of the 6 months (P1 also showing a minimum) and N2, N4, and N9 possibly increasing towards the end of the 6 months. These changes are, however, relatively small. Compounds N5 and N6 show a tendency for the rate of hardness increase to rise over the exposure period. The natural ageing behaviour was similar in that all materials either increased in hardness or were very little changed. A plateau effect was seen in natural ageing for compounds E, F, G, H, K, P and R, and hence does not correspond exactly with the plateaux in weathering.

8.1.3 Modulus For the modulus at 100%, there were no cases of a really sharp initial rise, although the curve fitting for compounds D, E and N10 show a small step. For most materials, there was either a rise in modulus or little change. However, in a number of cases there was a tendency for a modest decrease, notably compounds C, D, H, S, X, P5, N1, N5 and P9. Compound N6 showed a large initial drop in modulus and then a plateau. Also, in several cases there was some evidence for a maximum in the modulus–time curve. Most changes in modulus were fairly low with only compounds E, G, T, W and N10 having rises of over 20% and A, N, and P8 of over 40%. The drop in modulus for N6 was over 20%. The 100% modulus results are not entirely consistent with hardness in that there were some decreases and there is not good correlation for materials showing the greatest changes. There were no cases of 300% modulus showing a significant sharp initial rise. Only P1 and P10 had an appreciable tendency to have a maximum. Generally, the results were reasonably consistent with the 100% figures but at 300% A, M, and P8 had rather less modulus increase, and N had much lower increase. C and P1 showed a larger decrease, L no decrease and P, R and N3 a larger increase. The Hypalon T was completely inconsistent with 100% modulus increasing but 300% modulus decreased. The nitrile P10 was apparently inconsistent but at both levels it exhibited the same shaped curve with a maximum. It can be argued that good correlation between hardness and modulus would not be expected because of the effect of UV being confined to the surface. This would also affect correlation with the natural ageing.

8.1.4 Tensile Strength The great majority of materials show a decrease or are little changed in tensile strength over the 6 months. However, compounds S, N9, P5 and P6 show a tendency for tensile strength to increase. Compounds N1, N3, N10, P1, P7, P9 and P10 apparently exhibit slightly more complex behaviour. N1, N10 and P1 have a maximum in tensile strength whereas P7, P9 and P10 possibly have an inflexion and N3 a minimum. There is strong indication of a plateau effect in several of the materials, notably compounds B, C, D, F, G, L, R, and T which means that linear extrapolation would be misleading, as it could be for those with more complex behaviour.

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Ageing of Rubber - Accelerated Weathering and Ozone Test Results

For more than half the compounds the change in tensile strength is appreciable, with A, B, C, D, F, W, N, R, T, N10, P7, P8, P9 and P10 having over 20% decrease. The natural rubbers C and D and the nitrile P10 suffer very large decreases. There is significant rise in strength for EPDM P5. There are clearly some anomalies in comparison with the natural results, notably the reverse behaviour of the polysulphide W. A plateau effect was not seen in natural ageing.

8.1.5 Elongation at Break The great majority of materials show a decline in elongation at break or change little over the 6 months. Compounds S, X, N5, N6 and P1 possibly increase. Compounds J, N1, N4, N8, N9, P5 and P6 can be said to change relatively little. Also, the majority apparently decline to a plateau level. Compounds K and N5 appear to have a cyclic pattern but this could easily be an effect of variability. P8 follows the typical decrease but there is indication of a plateau being reached. The scatter for N2 is unusually large and it is difficult to see a definite trend. As for tensile strength, over half the materials exhibit considerable change although the elongation at break performance is perhaps not quite as bad. Compounds A, B, D, E, G, N, R, T, N7 and P8 decline by more than 20% with Hypalon T the worst. As a general rule, the tensile strength and elongation changes are not dissimilar. The only real exceptions are for compounds C, N7 and P1. C has a very much greater drop in strength than elongation, N7 a large drop in elongation but no change in strength, whilst for P1 the changes are significantly in opposite directions. Generally, the changes are not in conflict with the natural ageing results, but the latter did not show a plateau effect.

8.1.6 Effect of Temperature The estimates of change due to temperature over 6 months at 45 °C obtained by extrapolation from accelerated ageing (Appendix 2, Table 2) are subject to large uncertainty and may not even be valid. Taking them at face value (accelerated ageing results will be analysed in more detail in a subsequent report), the changes seen on weathering are very similar to the changes predicted for temperature effects in about 37% of the cases (each compound and property equals 1 case). In about 22% of the cases, the change predicted for temperature is significantly smaller or very much smaller than the changes seen in weathering, whilst in about 27%, the change predicted for temperature is significantly larger or very much larger than changes seen in weathering. In about 22% of the cases, there is complete disagreement in that the changes after weathering and predicted for temperature are in opposite directions. Very simplistically, this could be taken to indicate that in about 37% of the cases temperature accounts for all of the changes seen after weathering, that in 22% there is a significant weathering effect in addition to a temperature effect, but that in approaching 50% of the cases the temperature and weathering effects are different. It is highly unlikely that this is totally correct but it does indicate that in the majority of cases there is evidence of a significant effect due to UV and or moisture.

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When the estimates of net change due to weathering are taken and converted to change after 10 years under UK radiation conditions, the prediction is that in about 65% of the cases the weathering change would be significant (greater than 10%). Whilst again repeating that these predictions are somewhat speculative, there appears to be sufficient evidence to suggest that the effect of weathering alone should not be ignored and may be quite large for some materials. It is interesting to note differences between properties in respect of the weathering changes predicted. The modulus predictions show the most instances of significant weathering change (~83%) and the hardness least (~26%). Tensile strength and elongation show about 62% and 76%, respectively. Modulus results are probably the least reliable because of the uncertainty arising from the relatively low levels of force being measured but no explanation is offered as to why hardness shows the least change. Natural rubber compounds C and D exhibited very obvious surface cracking after the weathering exposure which was not seen in heat ageing tests. Hence, it is logical to conclude that there is firm evidence of a UV (and/or water) effect in these cases. The net weathering predictions for all properties of these materials is 10% or greater. The same is true for natural P8 and epoxidised natural rubber N3 other than hardness. Because of the uncertainties, it would be unwise to be very specific as to which materials are particularly prone to UV degradation. However, the predictions do show significant apparent dependence on formulation, for example, the polychloroprenes L, M and N, and very few materials were little affected for all properties. Elongation at break was reduced by heat ageing for almost all compounds, and in the remaining cases the change was small. For acrylate S, silicone X, fluorocarbon N5, Exxpro N6 and EPDMs P1 and P5, elongation at break increased on weathering. For hydrogenated nitrile N2, chlorinated PE N4 and Vamac P6, change in elongation at break after weathering and heat ageing were in opposite directions. This would imply different reactions for these materials in the two types of exposure. In some cases at least, the weathering effect might involve moisture. The changes in opposing directions are added to obtain the net weathering predictions and, hence, make these figures much larger than the individual results for weathering or heat ageing. The same additive effect applies to the other properties when changes are in opposite directions. This is significant in raising the net weathering predictions for hardness in the cases of fluorocarbon N5 and polyurethane N10, and for tensile strength in the cases of nitrile P, acrylate S and Hypalon T. Also, when the change from weathering is smaller than the change from heat ageing (in the same direction) it results in the predicted net effect being in the opposite direction to the total weathering change, and in some cases larger numerically than the total weathering change. If one was sceptical of predictions from accelerated heat ageing results and argued that the changes during weathering exposure had little contribution from temperature effects, it is interesting to see that there would then be approximately 61% of cases with a predicted weathering change of greater than 10% after 10 years in the UK. This is fractionally smaller than the figure after the temperature effect adjustment had been made and one would again conclude that it would be wise not to ignore weathering effects.

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Ageing of Rubber - Accelerated Weathering and Ozone Test Results

8.2 Ozone At 50 pphm (Appendix 3, Tables 1 and 2), compounds L, M, N, N1, N2, N4, N5, N6, N8, N9, N10, P1, P5, P6, P7, P9, S, T and X showed no cracking after 28 days. Compounds J and N7 had only Grade 1 cracks at the highest strains after 24 days. Compound P8 only cracked at the highest strain but rapidly developed Grade 3 cracks at 11 days and broke after 15 days. At 200 pphm (Appendix 3, Tables 3 and 4), compounds N1, N2, N4, N5, N6, N7, N8, N9, N10, P1, P5, P6, P7, P9 S, T and X showed no cracking after 28 days. Compound J had only Grade 1 cracks at the higher strains. It is a little curious that compound N7 showed cracking only at the highest strain at 50 pphm and that compound P8, although again very rapidly developing larger cracks, did not break. Hence, only compounds N1, N2, N4, N5, N6, N8, N9, N10, P1, P5, P6, P7, P9 S, T and X can be said to be completely ozone resistant. N7 is very close to being totally resistant and J and K perform extremely well. The results were generally not surprising. All the natural rubber and SBR compounds cracked relatively quickly, although the natural rubber compound P8 was notable for the improvement that is possible through compounding. The butyl rubbers J and K did crack but only at higher strains and longer times. All the polychloroprene compounds were clear at 50 pphm but the older compounds cracked at 200 pphm. The nitriles, except for the hydrogenated material N2, all cracked at 50 pphm, as did the polysulphide W. The epichlorohydrin N7 barely cracked at 50 pphm and was clear at 200 pphm. The remaining polymers appear to be totally resistant. The performance of polymers with relatively poor ozone resistance is very dependent on the formulation and, in particular, whether an effective antiozonant has been included. This is well illustrated by the difference between compounds A–D and compound P8. It should be noted that for many of the materials in this programme, ozone resistance was not a prime consideration and in consequence they were not well protected. The ranking in terms of the times to first cracking is conveniently seen in Figures 1 and 3 in Appendix 3. At 50 pphm compounds A, C, D, E, F, G, H, P, N3 and P3 had cracked at all strains in under 1 week. Similarly, the ranking in terms of times to grade 3 cracking is shown in Figures 2 and 4. The comparison of the two pairs of diagrams also shows the effect of increasing ozone concentration. In the context of this programme, the most important point to note from these ozone results is that cracking could be a rather more critical factor for the less resistant materials than, for example, heat ageing, if they were used in applications and under conditions conducive to ozone attack. It should also be noted that very little evidence of ozone attack was seen on the samples naturally aged for 40 years. With the exception of compression set, test pieces were not strained and in the shelf ageing conditions used, ambient ozone levels were probably very low. Hence, in contrast to the statement in the previous paragraph, in suitable conditions ozone will not be an important consideration. In thick articles, cracking confined to the surface has no more than cosmetic significance.

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If cracking does occur its severity, or the rate at which it progresses, is of interest. A very simple measure of the rate of crack growth can be deduced by comparing Figure 1 with Figure 2, and Figure 3 with Figure 4 (in Appendix 3). As an example, there is a clear difference between the natural rubber compounds A–D and the SBR compounds E–H. They all reach first cracking quickly but the SBRs reach grade 3 much more quickly than the natural rubbers. It is also interesting to note the pattern of cracking with strain level for non-resistant compounds. In some cases, a plot of time to cracking against strain appears to show a threshold strain below which cracking does not occur even at long times. A fairly good example is material P4 (Appendix 3, Figure 5). However, in the majority of cases in this work the possibility of a threshold strain is less clear. In the case of material W (Appendix 3, Figure 6), the exposures would need to be continued for longer times and for the least resistant materials tests at strains below 5% would be needed. Where there was some evidence for a threshold strain, it was generally about 5% or even lower which might be difficult to avoid in many applications. Occasionally, such as for material P10 (Appendix 3, Figure 7), it was significantly higher and this could be worth investigating more carefully.

9 CONCLUSIONS An accelerated weathering and ozone exposure programme involving a total of 38 rubber compounds has been successfully completed. The weathering results indicate that the effect of UV light may be significant for many rubbers and in some cases quite large, despite the presence of carbon black. Hence, it would be wise not to ignore the effect of weathering when estimating service life. The well-known fact that polymers vary greatly in their ozone resistance has again been demonstrated. Where non-resistant materials are involved, the likelihood of ozone attack being a problem in service should be carefully considered before undertaking long-term evaluation of thermal ageing performance.

REFERENCES 1.

R.P. Brown and T. Butler, Natural Ageing of Rubber—Changes in Physical Properties over 40 Years, Rapra Technology Limited, 2000.

2.

ISO 37 1994 Rubber, vulcanised or thermoplastic—Determination of tensile stressstrain properties.

3.

ISO 48 1994 Rubber, vulcanised or thermoplastic—Determination of hardness (Hardness between 10 IRHD and 1000 IRHD).

4.

ISO 4665 1998 Rubber, vulcanised—Resistance to weathering.

5.

ISO 1431-1 1989 Rubber, vulcanised or thermoplastic—Resistance to ozone cracking – Static strain test.

12

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

APPENDIX 1 COMPOUND DETAILS

© Copyright 2001 Rapra Technology Limited

13

Appendix 1

14

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber

Natural Rubber Ingredient

Amount (pphr)

Compound A – Standard

Smoked sheet

100

Curing conditions: 35' @ 141 °C

HAF black

50

Stearic acid

2.5

Pine tar

4.5

Zinc oxide

5

CBS

0.5

PBN

1.0

Sulphur

2.5

Compound B - Good Ageing

Smoked sheet

100

Curing conditions: 30' @ 148 °C

HAF black

50

Stearic acid

0.5

Pine tar

4.5

Zinc oxide

5

TMTD

2.5

PBN

1.0

MBT

1.0

Compound C - Mineral Filler Loaded

Smoked sheet

100

Curing conditions: 20' @ 141 °C

Stearic acid

1.5

Petroleum-based softener

5

Zinc oxide

5

CBS

0.5

PBN

1.0

Sulphur

2.5

Precipitated calcium carbonate

80

Compound D - Mineral Filler

Smoked sheet

100

(Heavy Loaded)

Stearic acid

1.5

Curing conditions: 20' @ 141 °C

Petroleum-based softener

25

Zinc oxide

5

CBS

0.6

PBN

1.0

Sulphur

3.2

Precipitated calcium carbonate

200

© Copyright 2001 Rapra Technology Limited

15

Appendix 1

Styrene Butadiene Rubber Ingredient

Amount (pphr)

Compound E - General Purpose

SBR 1500

100

Curing conditions: 40' @ 153 °C

HAF black

50

Stearic acid

2

Petroleum-based softener

4.5

Zinc oxide

3

CBS

1.0

PBN

1.0

Sulphur

1.75

Compound F - Good Ageing

SBR 1500

100

Curing conditions: 40' @ 153 °C

HAF black

50

Stearic acid

2

Petroleum-based softener

4.5

Zinc oxide

3

TMTD

3

PBN

1.0

MBTS

1.0

Compound G - General Purpose

SBR 1710

100

Curing conditions: 40' @ 153 °C

HAF black

50

Stearic acid

2

Petroleum-based softener

4.5

Zinc oxide

3

CBS

1.0

PBN

1.0

Sulphur

1.75

Compound H - Good Ageing

SBR 1710

100

Curing conditions: 50' @ 153 °C

HAF black

50

Stearic acid

2

Petroleum-based softener

4.5

Zinc oxide

3

TMTD

3

PBN

1.0

MBTS

1.0

16

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Butyl Rubber

Butyl Rubber Ingredient

Amount (pphr)

Compound J - General Purpose

Polysar 301 (high unsaturation)

100

Curing conditions: 40' @ 153 °C

FEF black

50

Zinc oxide

5

Stearic acid

2

MBT

0.5

TMT

1.0

Sulphur

2

Compound K - Good Ageing

Polysar 100 butyl (low unsaturation) 100

Curing conditions: 90' @ 153 °C

HAF black

50

Zinc oxide

25

Sulphur

2

MBTS

4

GMF

2

© Copyright 2001 Rapra Technology Limited

17

Appendix 1

Polychloroprene Ingredient

Amount (pphr)

Compound L - General Purpose

Neoprene type WRT

100

Curing conditions: 60' @ 153 °C

Light calcined magnesia

4

PBN

2

Stearic acid

0.5

SRF black

40

Petroleum-based softener

5

Robac 22

0.75

Zinc oxide

5

Compound M - Natural Ageing

Neoprene type WRT

100

Curing conditions: 60' @ 153 °C

Light calcined magnesia

4

Akroflex CD

2

Stearic acid

0.5

SRF black

50

Petroleum-based softener

5

DOTG

0.75

TMT-MS

0.75

Sulphur

0.75

Zinc oxide

5

Compound N - Heat Ageing

Neoprene type WRT

100

Curing conditions: 60' @ 153 °C

Light calcined magnesia

4

Aranox

0.5

Akroflex CD

2

Octamine

3.5

Stearic acid

0.5

SRF black

30

Precipitated calcium carbonate

90

Low volatile process oil

8

Robac 22

1

Zinc oxide

25

18

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Nitrile Rubber

Nitrile Rubber

Compound P - General Purpose

Ingredient

Amount (pphr)

Nitrile rubber

100

Curing conditions: 40' @ 153 °C

Compound R - Good Ageing

ca. 32-34% acrylonitrile) SRF black

50

DOP

20

Zinc oxide

5

Stearic acid

1

PBN

1

MBTS

1.5

Sulphur

1.5

Nitrile rubber

100

Curing conditions: 30' @ 153 °C

(ca. 35% acrylonitrile) SRF black

50

DOP

10

Polypropylene adipate

10

Zinc oxide

5

Stearic acid

1

Flectol H

2

TMTD

3

CBS

3

© Copyright 2001 Rapra Technology Limited

19

Appendix 1

Miscellaneous Ingredient

Amount (pphr)

Compound S - Acrylate Rubber

Hycar 4021

100

Curing conditions: 90' @ 153 °C

SRF black

50

Stearic acid

1

Triethylene tetramine

2

TMTM

1

Sulphur

3

Compound T -

Hypalon 20

100

Chlorosulphonated polyethylene

Precipitated calcium carbonate

45

Curing conditions: 30' @ 153 °C

Hydrogenated wood rosin

5

Litharge

20

MBTS

0.5

Flectol H

2

Process oil

10

Robac P25

0.75

Light calcined magnesia

10

Compound W - Polysulphide Rubber

Thiokol St

100

Curing conditions: 30' @ 141 °C

SRF black

60

Stearic acid

3

GMF

1.5

Zinc oxide

0.5

Dimethyl silicone gum (slightly unsaturated)

100

Diatomaceous silica

45

Fine silica

36

Ferric oxide

1

2,4-dichlorobenzoyl peroxide in silicone fluid

2

Compound X - Silicone Rubber Curing conditions: 10' @ 135 °C Post cure 1 h @ 150 °C, 24 h @ 250 °C in air

20

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compounds

New Compounds Ingredient

Amount (pphr)

Compound N1 - FVMQ

Silastic LS 238 OU

100

Curing conditions: 10' @ 171 °C,

Slastic HT-1

1

Post cure 4 h @ 200 °C in air

DHBP (50% silicone oil)

0.9

Compound N2 - HNBR

Zetpol 2000L

100

Curing conditions: 30' @ 180 °C

Spheron 4000

60

Naugard 445

1.5

Rhenogran ZMMBI 50

3

Zinc Oxide Active

3

Peroximon F40

8

Compound N3 - Epoxidised natural

Based on Epoxyprene 50, low

Curing conditions: 23.5' @ 141 °C

black loading, sulphur, TMTD, CBS and stabilised. Details confidential.

Compound N4 - Chlorinated polyethylene

Tyrin CM 3630

100

Curing conditions: 30' @ 180 °C

Flectol pastilles

0.2

Maglite DE

10

SRF N772 black

60

FEF N550 black

50

Britomya BSH

20

Bisoflex TOT

35

Drapex 39

4

Perkadox 14/40

6.25

Rhenogran TAC 50

5.6

Compound N5 - Fluorocarbon

Viton A-202C

100

Curing conditions: 20' @ 170 °C,

MT N990 Black

20

Post cure 24 h @ 225 °C in air

Sturge VE

6

Maglite DE

3

Compound N6 - Exxpro

Exxpro MDX90-10

100

Curing conditions: 45' @ 150 °C

HAF N330 Black

50

Stearic Acid

2

Zinc oxide

0.5

Tetrone A

1

© Copyright 2001 Rapra Technology Limited

21

Appendix 1

New Compounds (continued) Ingredient

Amount (pphr)

Compound N7 - Epichlorohydrin

Hydrin C65

100

Curing conditions: 37' @ 165 °C

SRF N772 black

70

Winnofil S

5

Paraplex G50

5

DOP

5

Vulkanox MB

1

Stearic acid

1

Span 60

1

Zisnet F

1

DPG

0.3

Maglite DE

5

Compound N8 - EPDM

Vistalon 7000

100

Curing conditions: 17.5' @ 165 °C

Zinc Oxide

10

Stearic Acid

2

SRF N772 Black

45

FEF N550 Black

60

Strukpar 2280

59

Sulphur

1

TMTD

2.5

ZDMC

2.67

NDBC

2

Sulfasan R

1.7

Compound N9 - EVA

Levapren 400

100

Curing conditions: 30' @ 165 °C

Staboxal PCD

3

Post cure 2 h @ 165 °C in steam

Zinc stearate

2

Vulkanox DDA

1

FEF N550 Black

30

Mistron Vapour

50

Perkadox 14/40

6

TAC

4

Compound N10 - PU

Adiprene FM

100

Curing conditions: 7.5' @ 165 °C

FEF N550 Black

40

DBP

5

Stearic Acid

1

Dicup 40C

3

Rhenogran TAC50

2

22

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant’s Compounds

Participant's Compounds Details of most of the formulations are not disclosed. Compound P1

Blend of two EPDM copolymers, one with high ethylene content and medium Mooney viscosity, the other with medium ethylene content and low Mooney viscosity. Contains carbon black, zinc oxide, TMQ, paraffinic process oil, dicumyl peroxide and a sulphur donor.

Compound P2

Silicone gum blended to give a methylvinylsiloxane content of 0.31% Silicone processing aid Precipitated silica Fumed silica Vinyl specific peroxide Urea

Compound P8

Natural rubber Activators Fillers Process aids 6PPD TMQ Antiozonant wax Sulphenamide TMTM Sulphur

100 7 105 50 3 2 4 0.75 0.1 1.5

(pphr)

Compound P10

NBR (28% ACN) Mineral fillers Silica Zinc oxide Stearic acid Antioxidants Sulphur cure system

100 100 25 10 1

(pphr)

© Copyright 2001 Rapra Technology Limited

23

24

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

APPENDIX 2 WEATHERING RESULTS

© Copyright 2001 Rapra Technology Limited

25

26

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber - Standard

Compound A (natural rubber - standard) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

75

81

5.8

8

Tensile Strength (MPa)

29.3

21.7

-7.6

-26

Elongation at Break (%)

516

32 7

-189

-37

Modulus at 100% (MPa)

3.38

5.03

1.65

49

Modulus at 300% (MPa)

15.7

20.2

4.5

29

Hardness (IRHD) Tensile Properties

Compound A (natural rubber - standard) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

7.7

10.7

-3

-4

Tensile Strength (MPa)

-25.9

-15.7

-10

-1 5

Elongation at Break (%)

-36.6

-42.4

6

8

Modulus at 100% (MPa)

48.8

11.2

38

54

Modulus at 300% (MPa)

28.7

10.8

18

26

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

27

Compound A

Hardness Compound A 86

84

Hardness (Micro-IRHD)

82

80

78

76

74

72

70 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound A 32.0

30.0

Tensile Strength (MPa)

28.0

26.0

24.0

22.0

20.0

18.0 0

30

60

90 Weathering Period (Days)

28

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber - Standard

Elongation at Break Compound A 650

600

Elongation at Break (%)

550

500

450

400

350

300

250 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound A 10.00

Modulus at 100% (MPa)

8.00

6.00

4.00

2.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

29

Compound A

Modulus at 300% Compound A 30.0

Modulus at 300% (MPa)

25.0

20.0

15.0

10.0

5.0

0.0 0

30

60

90

120

150

180

Weathering Period (Days)

30

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber - Good Ageing

Compound B (natural rubber - good ageing) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

68

72

4.2

6

Tensile Strength (MPa)

26.8

21.2

-5.6

-21

Elongation at Break (%)

608

47 2

-136

-22

Modulus at 100% (MPa)

1.92

2.08

0.16

8

Modulus at 300% (MPa)

10.9

11.9

1.0

9

Hardness (IRHD) Tensile Properties

Compound B (natural rubber - good ageing) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

6.2

5. 9

0

0

Tensile Strength (MPa)

-20.9

0.4

-21

-3 0

Elongation at Break (%)

-22.4

-24.8

2

3

Modulus at 100% (MPa)

8.3

67.2

-59

-8 4

Modulus at 300% (MPa)

8.9

17.4

-8

-1 2

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

31

Compound B

Hardness Compound B 76

74

Hardness (Micro-IRHD)

72

70

68

66

64

62

60 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound B 30.0

Tensile Strength (MPa)

28.0

26.0

24.0

22.0

20.0

18.0 0

30

60

90 Weathering Period (Days)

32

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber - Good Ageing

Elongation at Break Compound B 750

700

Elongation at Break (%)

650

600

550

500

450

400

350 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound B 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

33

Compound B

Modulus at 300% Compound B 20.0

Modulus at 300% (MPa)

15.0

10.0

5.0

0.0 0

30

60

90

120

150

180

Weathering Period (Days)

34

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber - Mineral Filler Loaded

Compound C (natural rubber - mineral filler loaded) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

54

58

3.8

7

Tensile Strength (MPa)

24.2

11.8

-12.4

-51

Elongation at Break (%)

644

54 0

-104

-16

Modulus at 100% (MPa)

1.41

1.30

-0.11

-8

Modulus at 300% (MPa)

4.63

3.82

-0.81

-17

Hardness (IRHD) Tensile Properties

Compound C (natural rubber - mineral filler loaded) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

7.0

0. 0

7

10

Tensile Strength (MPa)

-51.2

-3.3

-48

-6 8

Elongation at Break (%)

-16.1

-3.0

-13

-1 9

Modulus at 100% (MPa)

-7.8

15.6

-23

-3 3

Modulus at 300% (MPa)

-17.5

-0.2

-1 7

-2 5

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

35

Compound C

Hardness Compound C 66 64

Hardness (Micro-IRHD)

62 60 58 56 54 52 50 48 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound C 30.0

Tensile Strength (MPa)

25.0

20.0

15.0

10.0

5.0 0

30

60

90 Weathering Period (Days)

36

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber - Mineral Filler Loaded

Elongation at Break Compound C 750

700

Elongation at Break (%)

650

600

550

500

450

400 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound C 3.00

Modulus at 100% (MPa)

2.50

2.00

1.50

1.00

0.50

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

37

Compound C

Modulus at 300% Compound C 8.00

7.00

Modulus at 300% (MPa)

6.00

5.00

4.00

3.00

2.00

1.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

38

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber - Mineral Filler (Heavy Loaded)

Compound D (natural rubber - mineral filler (heavy loaded)) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

62

82

21

33

Tensile Strength (MPa)

11.3

5.47

-5.8

-52

Elongation at Break (%)

590

38 5

-205

-35

Modulus at 100% (MPa)

1.57

1.45

-0.12

-8

Modulus at 300% (MPa)

4.50

3.95

-0.55

-12

Hardness (IRHD) Tensile Properties

Compound D (natural rubber - mineral filler (heavy loaded)) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

33.4

-0.3

34

48

Tensile Strength (MPa)

-51.6

-25.6

-26

-3 7

Elongation at Break (%)

-34.7

-22.7

-12

-1 7

Modulus at 100% (MPa)

-7.6

29.3

-37

-5 3

Modulus at 300% (MPa)

-12.2

12.2

-24

-3 5

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

39

Compound D

Hardness Compound D 100

95

Hardness (Micro-IRHD)

90

85

80

75

70

65

60 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound D 14.0

Tensile Strength (MPa)

12.0

10.0

8.0

6.0

4.0

2.0 0

30

60

90 Weathering Period (Days)

40

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Natural Rubber - Mineral Filler (Heavy Loaded)

Elongation at Break Compound D 700 650

Elongation at Break (%)

600 550 500 450 400 350 300 250 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound D 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

41

Compound D

Modulus at 300% Compound D 8.00

7.00

Modulus at 300% (MPa)

6.00

5.00

4.00

3.00

2.00

1.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

42

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Styrene Butadiene Rubber - General Purpose

Compound E (styrene butadiene rubber - general purpose) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

67

72

5.2

8

Tensile Strength (MPa)

26.4

23.1

-3.3

-13

Elongation at Break (%)

486

36 7

-119

-24

Modulus at 100% (MPa)

2.66

3.47

0.81

30

Modulus at 300% (MPa)

14.8

18.4

3.6

24

Hardness (IRHD) Tensile Properties

Compound E (styrene butadiene rubber - general purpose) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 4 5 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

7.8

9.4

-2

-2

Tensile Strength (MPa)

-12.5

-4.5

-8

-1 1

Elongation at Break (%)

-24.5

-30.7

6

9

Modulus at 100% (MPa)

30.5

60.9

-30

-4 3

Modulus at 300% (MPa)

24.3

43.9

-20

-2 8

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

43

Compound E

Hardness Compound E 80 78 76

Hardness (Micro-IRHD)

74 72 70 68 66 64 62 60 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound E 32.0

Tensile Strength (MPa)

30.0

28.0

26.0

24.0

22.0

20.0 0

30

60

90 Weathering Period (Days)

44

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Styrene Butadiene Rubber - General Purpose

Elongation at Break Compound E 600

Elongation at Break (%)

550

500

450

400

350

300 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound E 6.00

Modulus at 100% (MPa)

5.00

4.00

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

45

Compound E

Modulus at 300% Compound E 30.0

Modulus at 300% (MPa)

25.0

20.0

15.0

10.0

5.0

0.0 0

30

60

90

120

150

180

Weathering Period (Days)

46

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Styrene Butadiene Rubber - Good Ageing

Compound F (styrene butadiene rubber - good ageing) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

64

66

1.9

3

Tensile Strength (MPa)

27.2

21.4

-5.8

-21

Elongation at Break (%)

589

48 3

-106

-18

Modulus at 100% (MPa)

1.93

2.00

0.07

4

Modulus at 300% (MPa)

11.3

11.2

-0.10

-0.9

Hardness (IRHD) Tensile Properties

Compound F (styrene butadiene rubber - good ageing) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

3.0

5. 8

-3

-4

Tensile Strength (MPa)

-21.3

-8.5

-13

-1 8

Elongation at Break (%)

-18.0

-9.8

-8

-1 2

Modulus at 100% (MPa)

3.6

37.8

-34

-4 9

Modulus at 300% (MPa)

-0.9

22.1

-23

-3 3

Hardness (IRHD) Tensile Properties

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Compound F

Hardness Compound F 70 69 68

Hardness (Micro-IRHD)

67 66 65 64 63 62 61 60 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound F 30.0

Tensile Strength (MPa)

28.0

26.0

24.0

22.0

20.0

18.0 0

30

60

90 Weathering Period (Days)

48

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Styrene Butadiene Rubber - Good Ageing

Elongation at Break Compound F 700

Elongation at Break (%)

650

600

550

500

450

400 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound F 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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49

Compound F

Modulus at 300% Compound F 20.0

Modulus at 300% (MPa)

15.0

10.0

5.0

0.0 0

30

60

90

120

150

180

Weathering Period (Days)

50

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Styrene Butadiene Rubber - General Purpose

Compound G (styrene butadiene rubber - general purpose) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

64

70

5.9

9

Tensile Strength (MPa)

21.8

19.1

-2.7

-12

Elongation at Break (%)

563

43 3

-130

-23

Modulus at 100% (MPa)

1.84

2.31

0.47

26

Modulus at 300% (MPa)

9.64

12.3

2.66

28

Hardness (IRHD) Tensile Properties

Compound G (styrene butadiene rubber - general purpose) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

9.2

7. 2

2

3

Tensile Strength (MPa)

-12.4

-12.4

0

0

Elongation at Break (%)

-23.1

-28.2

5

7

Modulus at 100% (MPa)

25.5

53.3

-28

-4 0

Modulus at 300% (MPa)

27.6

41.1

-14

-1 9

Hardness (IRHD) Tensile Properties

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Compound G

Hardness Compound G 74

72

Hardness (Micro-IRHD)

70

68

66

64

62

60 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound G 24.0

Tensile Strength (MPa)

22.0

20.0

18.0

16.0 0

30

60

90 Weathering Period (Days)

52

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Styrene Butadiene Rubber - General Purpose

Elongation at Break Compound G 700

650

Elongation at Break (%)

600

550

500

450

400

350 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound G 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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53

Compound G

Modulus at 300% Compound G 20.00

Modulus at 300% (MPa)

15.00

10.00

5.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

54

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Styrene Butadiene Rubber - Good Ageing

Compound H (styrene butadiene rubber - good ageing) Table 1. Property changes after six months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

59

62

3.1

5

Tensile Strength (MPa)

20.6

16.0

-4.6

-22

Elongation at Break (%)

604

54 3

-61

-10

Modulus at 100% (MPa)

1.44

1.37

-0.07

-5

Modulus at 300% (MPa)

8.34

7.64

-0.70

-8

Hardness (IRHD) Tensile Properties

Compound H (styrene butadiene rubber - good ageing) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

5.3

7. 6

-2

-3

Tensile Strength (MPa)

-22.3

-12.3

-10

-1 4

Elongation at Break (%)

-10.1

-42.9

33

47

Modulus at 100% (MPa)

-4.9

49.3

-54

-7 7

Modulus at 300% (MPa)

-8.4

81.1

-89

-12 8

Hardness (IRHD) Tensile Properties

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Compound H

Hardness Compound H 65 64 63

Hardness (Micro-IRHD)

62 61 60 59 58 57 56 55 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound H 24.0

Tensile Strength (MPa)

22.0

20.0

18.0

16.0

14.0

12.0 0

30

60

90 Weathering Period (Days)

56

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Styrene Butadiene Rubber - Good Ageing

Elongation at Break Compound H 750

700

Elongation at Break (%)

650

600

550

500

450

400

350 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound H 3.00

Modulus at 100% (MPa)

2.50

2.00

1.50

1.00

0.50

0.00 0

30

60

90 Weathering Period (Days)

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57

Compound H

Modulus at 300% Compound H 14.00

12.00

Modulus at 300% (MPa)

10.00

8.00

6.00

4.00

2.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

58

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Butyl Rubber - General Purpose

Compound J (butyl rubber - general purpose) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

67

67

0.4

0.6

Tensile Strength (MPa)

12.7

12.3

-0.4

-3

Elongation at Break (%)

419

41 2

-7

-2

Modulus at 100% (MPa)

2.62

2.56

-0.06

-2

Modulus at 300% (MPa)

9.64

9.52

-0.12

-1

Hardness (IRHD) Tensile Properties

Compound J (butyl rubber - general purpose) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

0.6

-1.5

2

3

Tensile Strength (MPa)

-3.1

-3.1

0

0

Elongation at Break (%)

-1.7

-8.1

6

9

Modulus at 100% (MPa)

-2.3

11.1

-13

-1 9

Modulus at 300% (MPa)

-1.2

0.0

-1

-2

Hardness (IRHD) Tensile Properties

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Compound J

Hardness Compound J 72 71 70

Hardness (Micro-IRHD)

69 68 67 66 65 64 63 62 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound J 15.0

Tensile Strength (MPa)

14.0

13.0

12.0

11.0

10.0 0

30

60

90 Weathering Period (Days)

60

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Butyl Rubber - General Purpose

Elongation at Break Compound J 500

Elongation at Break (%)

450

400

350

300 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound J 5.00

Modulus at 100% (MPa)

4.00

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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61

Compound J

Modulus at 300% Compound J 16.00

14.00

Modulus at 300% (MPa)

12.00

10.00

8.00

6.00

4.00

2.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

62

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Butyl Rubber - Good Ageing

Compound K (butyl rubber - good ageing) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

79

80

0.6

0.8

Tensile Strength (MPa)

14.0

13.4

-0.6

-4

Elongation at Break (%)

614

55 9

-55

-9

Modulus at 100% (MPa)

2.12

2.16

0.04

2

Modulus at 300% (MPa)

6.72

6.95

0.23

3

Hardness (IRHD) Tensile Properties

Compound K (butyl rubber - good ageing) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

0.8

5. 8

-5

-7

Tensile Strength (MPa)

-4.3

-13.6

9

13

Elongation at Break (%)

-9.0

-21.8

13

18

Modulus at 100% (MPa)

1.9

16.0

-14

-2 0

Modulus at 300% (MPa)

3.4

0.0

3

5

Hardness (IRHD) Tensile Properties

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Compound K

Hardness Compound K 85 84 83

Hardness (Micro-IRHD)

82 81 80 79 78 77 76 75 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound K 17.0

16.0

Tensile Strength (MPa)

15.0

14.0

13.0

12.0

11.0

10.0 0

30

60

90 Weathering Period (Days)

64

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Butyl Rubber - Good Ageing

Elongation at Break Compound K 750

Elongation at Break (%)

700

650

600

550

500

450 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound K 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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65

Compound K

Modulus at 300% Compound K 12.00

Modulus at 300% (MPa)

10.00

8.00

6.00

4.00

2.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

66

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Polychloroprene - General Purpose

Compound L (polychloroprene - general purpose) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

69

73

3.6

5

Tensile Strength (MPa)

21.6

18.9

-2.7

-13

Elongation at Break (%)

318

26 9

-49

-15

Modulus at 100% (MPa)

3.91

4.32

0.41

10

Modulus at 300% (MPa)

21.0

20.9

-0.10

-0.5

Hardness (IRHD) Tensile Properties

Compound L (polychloroprene - general purpose) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

5.2

1. 4

4

5

Tensile Strength (MPa)

-12.5

0.0

-13

-1 8

Elongation at Break (%)

-15.4

-5.7

-10

-1 4

Modulus at 100% (MPa)

10.5

-4.1

15

21

Modulus at 300% (MPa)

-0.5

0.5

-1

-1

Hardness (IRHD) Tensile Properties

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Compound L

Hardness Compound L 80

78

Hardness (Micro-IRHD)

76

74

72

70

68

66

64 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound L 26.0

Tensile Strength (MPa)

24.0

22.0

20.0

18.0

16.0

14.0 0

30

60

90 Weathering Period (Days)

68

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Polychloroprene - General Purpose

Elongation at Break Compound L 400

Elongation at Break (%)

350

300

250

200 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound L 7.00

6.00

Modulus at 100% (MPa)

5.00

4.00

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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69

Compound L

Modulus at 300% Compound L 30.0

Modulus at 300% (MPa)

25.0

20.0

15.0

10.0

5.0

0.0 0

30

60

90

120

150

180

Weathering Period (Days)

70

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Polychloroprene - Natural Ageing

Compound M (polychloroprene - natural ageing) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

69

74

5.0

7

Tensile Strength (MPa)

20.7

19.3

-1.4

-7

Elongation at Break (%)

332

29 6

-36

-11

Modulus at 100% (MPa)

4.00

4.49

0.49

12

Modulus at 300% (MPa)

18.7

19.7

1.0

5

Hardness (IRHD) Tensile Properties

Compound M (polychloroprene - natural ageing) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

7.2

6. 2

1

1

Tensile Strength (MPa)

-6.8

-4.8

-2

-3

Elongation at Break (%)

-10.8

-8.1

-3

-4

Modulus at 100% (MPa)

12.3

7. 0

5

8

Modulus at 300% (MPa)

5.3

5.9

-1

-1

Hardness (IRHD) Tensile Properties

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71

Compound M

Hardness Compound M 80

78

Hardness (Micro-IRHD)

76

74

72

70

68

66

64 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound M 26.0

Tensile Strength (MPa)

24.0

22.0

20.0

18.0

16.0

14.0 0

30

60

90 Weathering Period (Days)

72

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Polychloroprene - Natural Ageing

Elongation at Break Compound M 400

Elongation at Break (%)

350

300

250

200 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound M 6.00

Modulus at 100% (MPa)

5.00

4.00

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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73

Compound M

Modulus at 300% Compound M 30.0

Modulus at 300% (MPa)

25.0

20.0

15.0

10.0

5.0

0.0 0

30

60

90

120

150

180

Weathering Period (Days)

74

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Polychloroprene - Heat Ageing

Compound N (polychloroprene - heat ageing) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

80

91

11

14

Tensile Strength (MPa)

10.3

8.12

-2.2

-21

Elongation at Break (%)

368

28 4

-84

-23

Modulus at 100% (MPa)

2.89

4.19

1.3

45

Modulus at 300% (MPa)

8.28

8.54

0.26

3

Hardness (IRHD) Tensile Properties

Compound N (polychloroprene - heat ageing) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

13.6

3.5

10

14

Tensile Strength (MPa)

-21.2

0.0

-21

-3 0

Elongation at Break (%)

-22.8

-4.9

-18

-2 6

Modulus at 100% (MPa)

45.0

27.0

18

26

Modulus at 300% (MPa)

3.1

4. 6

-1

-2

Hardness (IRHD) Tensile Properties

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75

Compound N

Hardness Compound N 96 94 92

Hardness (Micro-IRHD)

90 88 86 84 82 80 78 76 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N 12.0

Tensile Strength (MPa)

11.0

10.0

9.0

8.0

7.0

6.0 0

30

60

90 Weathering Period (Days)

76

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Polychloroprene - Heat Ageing

Elongation at Break Compound N 450

Elongation at Break (%)

400

350

300

250

200 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N 6.00

Modulus at 100% (MPa)

5.00

4.00

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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77

Compound N

Modulus at 300% Compound N 14.00

12.00

Modulus at 300% (MPa)

10.00

8.00

6.00

4.00

2.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

78

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Nitrile Rubber - General Purpose

Compound P (nitrile rubber - general purpose) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

55

59

3.7

7

Tensile Strength (MPa)

17.4

16.6

-0.8

-5

Elongation at Break (%)

531

44 4

-87

-16

Modulus at 100% (MPa)

1.86

2.01

0.15

8

Modulus at 300% (MPa)

8.8

10.7

1.9

22

Hardness (IRHD) Tensile Properties

Compound P (nitrile rubber - general purpose) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

6.7

11.8

-5

-7

Tensile Strength (MPa)

-4.6

11.5

-16

-2 3

Elongation at Break (%)

-16.4

-32.4

16

23

Modulus at 100% (MPa)

8.1

29.6

-22

-3 1

Modulus at 300% (MPa)

21.6

54.5

-33

-4 7

Hardness (IRHD) Tensile Properties

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79

Compound P

Hardness Compound P 64

62

Hardness (Micro-IRHD)

60

58

56

54

52

50 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P 24.0

22.0

Tensile Strength (MPa)

20.0

18.0

16.0

14.0

12.0

10.0 0

30

60

90 Weathering Period (Days)

80

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Nitrile Rubber - General Purpose

Elongation at Break Compound P 650

600

Elongation at Break (%)

550

500

450

400

350

300 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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81

Compound P

Modulus at 300% Compound P 16.00

14.00

Modulus at 300% (MPa)

12.00

10.00

8.00

6.00

4.00

2.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

82

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Polychloroprene - Good Ageing

Compound R (polychloroprene - good ageing) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

55

60

5.1

9

Tensile Strength (MPa)

23.1

17.2

-5.9

-26

Elongation at Break (%)

650

50 9

-141

-22

Modulus at 100% (MPa)

1.67

1.85

0.18

11

Modulus at 300% (MPa)

7.37

8.86

1.5

20

Hardness (IRHD) Tensile Properties

Compound R (polychloroprene - good ageing) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

9.3

17.6

-8

-1 2

Tensile Strength (MPa)

-25.5

-

-

-

Elongation at Break (%)

-21.7

-55.1

33

48

Modulus at 100% (MPa)

10.8

63.5

-53

-7 5

Modulus at 300% (MPa)

20.2

34.2

-14

-2 0

Hardness (IRHD) Tensile Properties

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83

Compound R

Hardness Compound R 66

64

Hardness (Micro-IRHD)

62

60

58

56

54

52 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound R 26.0

Tensile Strength (MPa)

24.0

22.0

20.0

18.0

16.0

14.0 0

30

60

90 Weathering Period (Days)

84

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Nitrile Rubber - Good Ageing

Elongation at Break Compound R 750

700

Elongation at Break (%)

650

600

550

500

450

400 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound R 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

85

Compound R

Modulus at 300% Compound R 14.00

12.00

Modulus at 300% (MPa)

10.00

8.00

6.00

4.00

2.00

0.00 0

30

60

90

120

150

180

Weathering Period (Days)

86

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Miscellaneous - Acrylate Rubber

Compound S (miscellaneous - acrylate rubber) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

52

52

0.4

0.8

Tensile Strength (MPa)

11.3

11.6

0.3

3

Elongation at Break (%)

223

241

18

8

Modulus at 100% (MPa)

3.47

3.18

-0.29

-8

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound S (miscellaneous - acrylate rubber) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

0.8

0. 0

1

1

Tensile Strength (MPa)

2.7

-19.7

22

32

Elongation at Break (%)

8.1

-13.5

22

31

Modulus at 100% (MPa)

-8.4

-0.9

-7

-1 1

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

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87

Compound S

Hardness Compound S 60

58

Hardness (Micro-IRHD)

56

54

52

50

48

46 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound S 14.0

Tensile Strength (MPa)

13.0

12.0

11.0

10.0

9.0 0

30

60

90 Weathering Period (Days)

88

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Miscellaneous - Acrylate Rubber

Elongation at Break Compound S 300

280

Elongation at Break (%)

260

240

220

200

180

160 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound S 6.00

Modulus at 100% (MPa)

5.00

4.00

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

89

Compound S

90

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Miscellaneous - Chlorosulphonated Polyethylene

Compound T (miscellaneous - chlorosulphonated polyethylene) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

53

67

14

27

Tensile Strength (MPa)

8.00

6.00

-2.0

-25

Elongation at Break (%)

438

26 3

-175

-40

Modulus at 100% (MPa)

2.88

3.99

1.1

39

Modulus at 300% (MPa)

6.27

5.23

-1.0

-17

Hardness (IRHD) Tensile Properties

Compound T (miscellaneous - chlorosulphonated polyethylene) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

26.6

11.7

15

21

Tensile Strength (MPa)

-25.0

27.5

-53

-7 5

Elongation at Break (%)

-40.0

-37.4

-3

-4

Modulus at 100% (MPa)

38.5

-2.1

41

58

Modulus at 300% (MPa)

-16.6

-

-

-

Hardness (IRHD) Tensile Properties

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91

Compound T

Hardness Compound T 75

Hardness (Micro-IRHD)

70

65

60

55

50 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound T 10.0

Tensile Strength (MPa)

9.0

8.0

7.0

6.0

5.0

4.0 0

30

60

90 Weathering Period (Days)

92

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Miscellaneous - Chlorosulphonated Polyethylene

Elongation at Break Compound T 500

Elongation at Break (%)

450

400

350

300

250

200 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound T 6.00

Modulus at 100% (MPa)

5.00

4.00

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

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93

Compound T

Modulus at 300% Compound T 10.0 9.0 8.0

Modulus at 300% (MPa)

7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 0

30

60

90

120

150

180

Weathering Period (Days)

94

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Miscellaneous - Polysulphide Rubber

Compound W (miscellaneous - polysulphide rubber) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

63

70

7.3

12

Tensile Strength (MPa)

5.69

5.32

-0.37

-7

Elongation at Break (%)

310

24 7

-63

-20

Modulus at 100% (MPa)

2.01

2.43

0.42

21

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound W (miscellaneous - polysulphide rubber) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

11.6

11.0

1

1

Tensile Strength (MPa)

-6.5

-1.6

-5

-7

Elongation at Break (%)

-20.3

-12.9

-7

-1 1

Modulus at 100% (MPa)

20.9

19.9

1

1

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

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95

Compound W

Hardness Compound W 76

74

Hardness (Micro-IRHD)

72

70

68

66

64

62

60 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound W 8.0

Tensile Strength (MPa)

7.0

6.0

5.0

4.0

3.0 0

30

60

90 Weathering Period (Days)

96

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Miscellaneous - Polysulphide Rubber

Elongation at Break Compound W 340

320

Elongation at Break (%)

300

280

260

240

220

200 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound W 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

97

Compound W

98

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Miscellaneous - Silicone Rubber

Compound X (miscellaneous - silicone rubber) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

54

55

1.2

2

Tensile Strength (MPa)

7.03

7.16

0.13

2

Elongation at Break (%)

219

239

20

9

Modulus at 100% (MPa)

2.89

2.65

-0.24

-8

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound X (miscellaneous - silicone rubber) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

2.2

0. 0

2

3

Tensile Strength (MPa)

1.8

-0.1

2

3

Elongation at Break (%)

9.1

-8.2

17

25

Modulus at 100% (MPa)

-8.3

-1.4

-7

-1 0

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

99

Compound X

Hardness Compound X 60

Hardness (Micro-IRHD)

58

56

54

52

50 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound X 9.0

Tensile Strength (MPa)

8.0

7.0

6.0

5.0 0

30

60

90 Weathering Period (Days)

100

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Miscellaneous - Silicone Rubber

Elongation at Break Compound X 300

280

Elongation at Break (%)

260

240

220

200

180

160

140 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound X 5.00

Modulus at 100% (MPa)

4.00

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

101

Compound X

102

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - FVMQ

Compound N1 (FVMQ) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

72

72

0.0

0

Tensile Strength (MPa)

7.5

7. 1

-0.4

-5

Elongation at Break (%)

168

17 6

8

5

Modulus at 100% (MPa)

4.29

4.03

-0.26

-6

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound N1 (FVMQ) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

0.0

-1.4

1

2

Tensile Strength (MPa)

-5.2

-2.7

-3

-4

Elongation at Break (%)

4.9

1.2

4

5

Modulus at 100% (MPa)

-6.1

48.7

-55

-7 8

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

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103

Compound N1

Hardness Compound N1 76

75

Hardness (Micro-IRHD)

74

73

72

71

70

69

68 0

30

60

90

120

150

180

150

180

Weathering Period (Days)

Tensile Strength Compound N1 10.00

Tensile Strength (MPa)

9.00

8.00

7.00

6.00

5.00 0

30

60

90

120

Weathering Period (Days)

104

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - FVMQ

Elongation at Break Compound N1 220

Elongation at Break (%)

200

180

160

140

120 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N1

Modulus at 100% (MPa)

6.00

5.00

4.00

3.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

105

Compound N1

106

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - HNBR

Compound N2 (HNBR) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

68

71

3.2

5

Tensile Strength (MPa)

21.3

21.0

-0.2

-1

Elongation at Break (%)

563

53 9

-24

-4

Modulus at 100% (MPa)

2.68

2.87

0.19

7

Modulus at 300% (MPa)

14.3

15.9

1.7

12

Hardness (IRHD) Tensile Properties

Compound N2 (HNBR) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

4.7

30.9

-26

-3 7

Tensile Strength (MPa)

-1.0

23.5

-24

-3 5

Elongation at Break (%)

-4.3

3.2

-7

-1 1

Modulus at 100% (MPa)

7.1

941.0

-934

-133 4

Modulus at 300% (MPa)

11.6

-2.1

14

20

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

107

Compound N2

Hardness Compound N2 75

Hardness (Micro-IRHD)

73

71

69

67

65 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N2

Tensile Strength (MPa)

24.0

22.0

20.0

18.0 0

30

60

90 Weathering Period (Days)

108

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - HNBR

Elongation at Break Compound N2 650

Elongation at Break (%)

600

550

500

450

400 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N2 5.00

Modulus at 100% (MPa)

4.00

3.00

2.00

1.00 0

30

60

90 Weathering Period (Days)

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109

Compound N2

Modulus at 300% Compound N2 20.0

Modulus at 300% (MPa)

18.0

16.0

14.0

12.0

10.0 0

30

60

90

120

150

180

Weathering Period (Days)

110

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Epoxidised Natural

Compound N3 (epoxidised natural) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

55

60

4.9

9

Tensile Strength (MPa)

24.8

21.5

-3.3

-13

Elongation at Break (%)

600

50 5

-95

-16

Modulus at 100% (MPa)

1.87

1.98

0.11

6

Modulus at 300% (MPa)

6.71

8.98

2.27

34

Hardness (IRHD) Tensile Properties

Compound N3 (epoxidised natural) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

8.9

7. 3

2

2

Tensile Strength (MPa)

-13.2

-83.8

71

10 1

Elongation at Break (%)

-15.8

-76.3

61

86

Modulus at 100% (MPa)

5.9

27.3

-21

-3 1

Modulus at 300% (MPa)

33.8

44.6

-11

-1 5

Hardness (IRHD) Tensile Properties

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111

Compound N3

Hardness Compound N3 64

Hardness (Micro-IRHD)

62

60

58

56

54

52 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N3

Tensile Strength (MPa)

30.0

25.0

20.0

15.0 0

30

60

90 Weathering Period (Days)

112

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Epoxidised Natural

Elongation at Break Compound N3 700

Elongation at Break (%)

650

600

550

500

450

400 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N3 3.00

Modulus at 100% (MPa)

2.50

2.00

1.50

1.00 0

30

60

90 Weathering Period (Days)

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113

Compound N3

Modulus at 300% Compound N3 12.00

Modulus at 300% (MPa)

10.00

8.00

6.00

4.00 0

30

60

90

120

150

180

Weathering Period (Days)

114

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Chlorinated Polyethylene

Compound N4 (chlorinated polyethylene) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

85

88

3.2

4

Tensile Strength (MPa)

15.0

13.4

-1.5

-10

Elongation at Break (%)

196

18 1

-15

-8

Modulus at 100% (MPa)

8.07

8.37

0.30

4

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound N4 (chlorinated polyethylene) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

3.8

0. 0

4

5

Tensile Strength (MPa)

-10.2

-0.7

-10

-1 4

Elongation at Break (%)

-7.7

5.1

-13

-1 8

Modulus at 100% (MPa)

3.7

14.1

-10

-1 5

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

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115

Compound N4

Hardness Compound N4 92

Hardness (Micro-IRHD)

90

88

86

84

82 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N4 20.0

Tensile Strength (MPa)

18.0

16.0

14.0

12.0

10.0 0

30

60

90 Weathering Period (Days)

116

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Chlorinated Polyethylene

Elongation at Break Compound N4 300

Elongation at Break (%)

250

200

150

100 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N4 12.00

Modulus at 100% (MPa)

10.00

8.00

6.00

4.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

117

Compound N4

118

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Fluorocarbon

Compound N5 (fluorocarbon) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

71

74

3.4

5

Tensile Strength (MPa)

12.9

12.6

-0.3

-2

Elongation at Break (%)

218

242

24

11

Modulus at 100% (MPa)

5.22

5.08

-0.14

-3

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound N5 (fluorocarbon) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

4.8

-2.8

8

11

Tensile Strength (MPa)

-2.3

-0.8

-2

-2

Elongation at Break (%)

10.9

0.0

11

16

Modulus at 100% (MPa)

-2.7

-0.2

-2

-4

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

119

Compound N5

Hardness Compound N5 80

78

Hardness (Micro-IRHD)

76

74

72

70

68

66 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N5 15.0

Tensile Strength (MPa)

14.0

13.0

12.0

11.0

10.0 0

30

60

90 Weathering Period (Days)

120

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Fluorocarbon

Elongation at Break Compound N5 280

Elongation at Break (%)

260

240

220

200

180 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N5 7.00

6.50

Modulus at 100% (MPa)

6.00

5.50

5.00

4.50

4.00

3.50

3.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

121

Compound N5

122

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Exxpro

Compound N6 (Exxpro) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

67

71

3.5

5

Tensile Strength (MPa)

18.1

17.2

-0.9

-5

Elongation at Break (%)

215

237

22

10

Modulus at 100% (MPa)

6.70

5.22

-1.48

-22

Modulus at 300% (MPa)

-

-

-

Hardness (IRHD) Tensile Properties

Compound N6 (Exxpro) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

5.2

9. 0

-4

-5

Tensile Strength (MPa)

-5.0

-22.7

18

25

Elongation at Break (%)

10.2

-25.6

36

51

Modulus at 100% (MPa)

-22.1

0.0

-22

-3 2

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

123

Compound N6

Hardness Compound N6 76

74

Hardness (Micro-IRHD)

72

70

68

66

64

62

60 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N6 20.0

Tensile Strength (MPa)

19.0

18.0

17.0

16.0

15.0 0

30

60

90 Weathering Period (Days)

124

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Exxpro

Elongation at Break Compound N6 280

Elongation at Break (%)

260

240

220

200

180 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N6 9.00

Modulus at 100% (MPa)

8.00

7.00

6.00

5.00

4.00

3.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

125

Compound N6

126

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Epichlorohydrin

Compound N7 (epichlorohydrin) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

79

84

5.3

7

Tensile Strength (MPa)

9.6

9. 6

0

0

Elongation at Break (%)

299

211

-87

-29

Modulus at 100% (MPa)

4.47

5.04

0.57

13

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound N7 (epichlorohydrin) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

6.7

3. 8

3

4

0.0

1.6

-2

-2

Elongation at Break (%)

-29.2

-43.1

14

20

Modulus at 100% (MPa)

12.8

3. 6

9

13

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties Tensile Strength (MPa)

© Copyright 2001 Rapra Technology Limited

127

Compound N7

Hardness Compound N7 90 88 86

Hardness (Micro-IRHD)

84 82 80 78 76 74 72 70 0

30

60

90

120

150

180

150

180

Weathering Period (Days)

Tensile Strength Compound N7 12.00

Tensile Strength (MPa)

11.00

10.00

9.00

8.00

7.00 0

30

60

90

120

Weathering Period (Days)

128

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - Epichlorohydrin

Elongation at Break Compound N7 400

Elongation at Break (%)

350

300

250

200

150

100 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N7 6.50

6.00

Modulus at 100% (MPa)

5.50

5.00

4.50

4.00

3.50

3.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

129

Compound N7

130

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - EPDM

Compound N8 (EPDM) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

79

79

0.0

0

Tensile Strength (MPa)

16.3

15.9

-0.5

-3

Elongation at Break (%)

365

35 3

-12

-3

Modulus at 100% (MPa)

4.38

4.24

-0.14

-3

Modulus at 300% (MPa)

14.0

14.1

0.1

1

Hardness (IRHD) Tensile Properties

Compound N8 (EPDM) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

0.0

0. 0

0

0

Tensile Strength (MPa)

-2.9

0.6

-3

-5

Elongation at Break (%)

-3.3

-27.1

24

34

Modulus at 100% (MPa)

-3.2

34.5

-38

-5 4

Modulus at 300% (MPa)

1.0

25.7

-25

-3 5

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

131

Compound N8

Hardness Compound N8 84

Hardness (Micro-IRHD)

82

80

78

76

74 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N8 20.0

Tensile Strength (MPa)

18.0

16.0

14.0

12.0 0

30

60

90 Weathering Period (Days)

132

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - EPDM

Elongation at Break Compound N8 500

Elongation at Break (%)

450

400

350

300

250

200 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N8 6.00

Modulus at 100% (MPa)

5.50

5.00

4.50

4.00

3.50

3.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

133

Compound N8

Modulus at 300% Compound N8 20.0

Modulus at 300% (MPa)

18.0

16.0

14.0

12.0

10.0 0

30

60

90

120

150

180

Weathering Period (Days)

134

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - EVA

Compound N9 (EVA) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

79

82

3.2

4

Tensile Strength (MPa)

11.7

12.1

0.4

4

Elongation at Break (%)

173

187

14

8

Modulus at 100% (MPa)

7.93

8.91

0.98

12

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound N9 (EVA) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

4.0

5. 1

-1

-2

Tensile Strength (MPa)

3.8

-0.9

5

7

Elongation at Break (%)

8.0

-6.4

14

21

Modulus at 100% (MPa)

12.4

-1.3

14

20

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

135

Compound N9

Hardness Compound N9 85

Hardness (Micro-IRHD)

83

81

79

77

75 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N9 14.0

Tensile Strength (MPa)

13.0

12.0

11.0

10.0

9.0 0

30

60

90 Weathering Period (Days)

136

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - EVA

Elongation at Break Compound N9

Elongation at Break (%)

250

200

150

100 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N9 11.00

Modulus at 100% (MPa)

10.00

9.00

8.00

7.00

6.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

137

Compound N9

138

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - PU

Compound N10 (PU) Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

74

79

4.6

6

Tensile Strength (MPa)

14.7

17.2

2.5

17

Elongation at Break (%)

195

174

-21

-11

Modulus at 100% (MPa)

6.24

8.51

2.27

36

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound N10 (PU) Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

6.2

-39.2

45

65

Tensile Strength (MPa)

17.0

-50.7

68

97

Elongation at Break (%)

-10.8

-50.8

40

57

Modulus at 100% (MPa)

36.4

-84.0

120

17 2

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

139

Compound N10

Hardness Compound N10 86

84

Hardness (Micro-IRHD)

82

80

78

76

74

72

70 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound N10 20.0

Tensile Strength (MPa)

18.0

16.0

14.0

12.0 0

30

60

90 Weathering Period (Days)

140

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

New Compound - PU

Elongation at Break Compound N10

Elongation at Break (%)

250

200

150

100 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound N10 11.00

10.00

Modulus at 100% (MPa)

9.00

8.00

7.00

6.00

5.00

4.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

141

Compound N10

142

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - EPR

Compound P1 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

71

71

-0.3

-0.4

Tensile Strength (MPa)

13.2

12.0

-1.1

-9

Elongation at Break (%)

504

556

51

10

Modulus at 100% (MPa)

2.15

2.10

-0.05

-2

Modulus at 300% (MPa)

8.47

7.32

-1.15

-14

Hardness (IRHD) Tensile Properties

Compound P1 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

-0.4

-1.4

1

1

Tensile Strength (MPa)

-8.7

0.8

-9

-1 4

Elongation at Break (%)

10.2

0.0

10

15

Modulus at 100% (MPa)

-2.3

291.6

-294

-42 0

Modulus at 300% (MPa)

-13.6

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

143

Compound P1

Hardness Compound P1 76 75 74

Hardness (Micro-IRHD)

73 72 71 70 69 68 67 66 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P1 18.0

17.0

Tensile Strength (MPa)

16.0

15.0

14.0

13.0

12.0

11.0

10.0 0

30

60

90 Weathering Period (Days)

144

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - EPR

Elongation at Break Compound P1 600

Elongation at Break (%)

550

500

450

400 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P1 4.00

Modulus at 100% (MPa)

3.00

2.00

1.00

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

145

Compound P1

Modulus at 300% Compound P1 14.00

Modulus at 300% (MPa)

12.00

10.00

8.00

6.00

4.00 0

30

60

90

120

150

180

Weathering Period (Days)

146

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Medium Nitrile Rubber

Compound P3 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

83

85

2.0

2

Tensile Strength (MPa)

15.7

14.7

-1.0

-7

Elongation at Break (%)

242

22 8

-14

-6

Modulus at 100% (MPa)

10.6

9.9

-0.8

-7

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound P3 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

2.4

4. 8

-2

-3

Tensile Strength (MPa)

-6.6

-1.9

-5

-7

Elongation at Break (%)

-5.7

-35.1

29

42

Modulus at 100% (MPa)

-7.2

18.9

-26

-3 7

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

147

Compound P3

Hardness Compound P3 90

88

Hardness (Micro-IRHD)

86

84

82

80

78

76 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P3 18.0

Tensile Strength (MPa)

17.0

16.0

15.0

14.0

13.0

12.0 0

30

60

90 Weathering Period (Days)

148

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Medium Nitrile Rubber

Elongation at Break Compound P3 280

270

Elongation at Break (%)

260

250

240

230

220

210

200 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P3 15.00 14.00 13.00

Modulus at 100% (MPa)

12.00 11.00 10.00 9.00 8.00 7.00 6.00 5.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

149

Compound P3

150

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Nitrile Rubber

Compound P4 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

67

67

0.2

0.3

Tensile Strength (MPa)

23.7

20.0

-3.7

-15

Elongation at Break (%)

514

44 3

-71

-14

Modulus at 100% (MPa)

3.02

3.22

0.2

7

Modulus at 300% (MPa)

13.1

13.6

0.5

4

Hardness (IRHD) Tensile Properties

Compound P4 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

0.3

10.4

-10

-1 4

Tensile Strength (MPa)

-15.5

-42.2

27

38

Elongation at Break (%)

-13.9

-69.5

56

79

Modulus at 100% (MPa)

6.6

39.4

-33

-4 7

Modulus at 300% (MPa)

4.0

61.8

-58

-8 3

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

151

Compound P4

Hardness Compound P4 74

72

Hardness (Micro-IRHD)

70

68

66

64

62

60 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P4 26.0

Tensile Strength (MPa)

24.0

22.0

20.0

18.0

16.0 0

30

60

90 Weathering Period (Days)

152

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Nitrile Rubber

Elongation at Break Compound P4 600

Elongation at Break (%)

550

500

450

400

350 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P4 5.00

Modulus at 100% (MPa)

4.50

4.00

3.50

3.00

2.50

2.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

153

Compound P4

Modulus at 300% Compound P4 18.0

Modulus at 300% (MPa)

16.0

14.0

12.0

10.0 0

30

60

90

120

150

180

Weathering Period (Days)

154

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - EPDM

Compound P5 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

71

71

0.0

0.0

Tensile Strength (MPa)

12.1

13.3

1.2

10

Elongation at Break (%)

139

150

11

8

Modulus at 100% (MPa)

6.62

6.09

-0.53

-8

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound P5 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

0.0

5. 5

-6

-8

Tensile Strength (MPa)

9.7

3. 3

6

9

Elongation at Break (%)

7.8

-23.0

31

44

Modulus at 100% (MPa)

-8.0

-

-

-

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

155

Compound P5

Hardness Compound P5 75

74

Hardness (Micro-IRHD)

73

72

71

70

69

68

67 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P5 17.0

16.0

Tensile Strength (MPa)

15.0

14.0

13.0

12.0

11.0

10.0

9.0 0

30

60

90 Weathering Period (Days)

156

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - EPDM

Elongation at Break Compound P5 200

Elongation at Break (%)

180

160

140

120

100 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P5 9.00

Modulus at 100% (MPa)

8.00

7.00

6.00

5.00

4.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

157

Compound P5

158

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Vamac G

Compound P6 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

78

83

4.9

6

Tensile Strength (MPa)

11.6

12.1

0.5

4

Elongation at Break (%)

233

22 7

-6

-2

Modulus at 100% (MPa)

7.37

8.25

0.88

12

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound P6 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

6.3

23.1

-17

-2 4

Tensile Strength (MPa)

3.9

0. 0

4

6

Elongation at Break (%)

-2.4

4.7

-7

-1 0

Modulus at 100% (MPa)

11.9

42.5

-31

-4 4

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

159

Compound P6

Hardness Compound P6 89

87

Hardness (Micro-IRHD)

85

83

81

79

77

75 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P6 14.0

Tensile Strength (MPa)

13.0

12.0

11.0

10.0 0

30

60

90 Weathering Period (Days)

160

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Vamac G

Elongation at Break Compound P6

Elongation at Break (%)

300

250

200

150 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P6 10.00

Modulus at 100% (MPa)

9.00

8.00

7.00

6.00

5.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

161

Compound P6

162

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - W Type Polychloroprene

Compound P7 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

66

73

7.4

11

Tensile Strength (MPa)

15.2

12.1

-3.1

-20

Elongation at Break (%)

307

25 3

-54

-18

Modulus at 100% (MPa)

3.36

4.04

0.68

20

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

Compound P7 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

11.2

6. 1

5

7

Tensile Strength (MPa)

-20.1

-6.6

-14

-1 9

Elongation at Break (%)

-17.6

-18.6

1

1

Modulus at 100% (MPa)

20.2

25.9

-6

-8

Modulus at 300% (MPa)

-

-

-

-

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

163

Compound P7

Hardness Compound P7 77

75

Hardness (Micro-IRHD)

73

71

69

67

65

63 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P7 17.0

16.0

Tensile Strength (MPa)

15.0

14.0

13.0

12.0

11.0

10.0 0

30

60

90 Weathering Period (Days)

164

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - W Type Polychloroprene

Elongation at Break Compound P7

Elongation at Break (%)

350

300

250

200 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P7 5.00

Modulus at 100% (MPa)

4.50

4.00

3.50

3.00

2.50

2.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

165

Compound P7

166

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Natural Rubber

Compound P8 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

58

69

10.9

19

Tensile Strength (MPa)

12.0

9. 4

-2.6

-22

Elongation at Break (%)

542

38 5

-157

-29

Modulus at 100% (MPa)

1.00

1.81

0.81

81

Modulus at 300% (MPa)

5.63

7.16

1.53

27

Hardness (IRHD) Tensile Properties

Compound P8 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

18.8

1.7

17

24

Tensile Strength (MPa)

-21.8

0.8

-23

-3 2

Elongation at Break (%)

-28.9

-13.1

-16

-2 3

Modulus at 100% (MPa)

81.0

145.0

-64

-9 1

Modulus at 300% (MPa)

27.2

-2.3

29

42

Hardness (IRHD) Tensile Properties

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167

Compound P8

Hardness Compound P8 73 71

Hardness (Micro-IRHD)

69 67 65 63 61 59 57 55 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P8 14.0

Tensile Strength (MPa)

13.0

12.0

11.0

10.0

9.0

8.0 0

30

60

90 Weathering Period (Days)

168

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Natural Rubber

Elongation at Break Compound P8 600

Elongation at Break (%)

550

500

450

400

350

300 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P8 3.00

Modulus at 100% (MPa)

2.50

2.00

1.50

1.00

0.50

0.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

169

Compound P8

Modulus at 300% Compound P8 10.00

Modulus at 300% (MPa)

9.00

8.00

7.00

6.00

5.00

4.00 0

30

60

90

120

150

180

Weathering Period (Days)

170

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Santoprene 101 55 V185

Compound P9 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

68

68

-0.1

-0.1

Tensile Strength (MPa)

5.8

4.4

-1.4

-24

Elongation at Break (%)

460

397

-63

-14

Modulus at 100% (MPa)

1.98

1.75

-0.23

-12

Modulus at 300% (MPa)

4.10

3.55

-0.55

-13

Hardness (IRHD) Tensile Properties

Compound P9 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

-0.1

0.0

0

0

Tensile Strength (MPa)

-23.8

2.9

-27

-3 8

Elongation at Break (%)

-13.7

-

-

-

Modulus at 100% (MPa)

-11.6

-2.0

-10

-1 4

Modulus at 300% (MPa)

-13.4

-1.2

-12

-1 7

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

171

Compound P9

Hardness Compound P9 72

71

Hardness (Micro-IRHD)

70

69

68

67

66

65 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P9 7.00

Tensile Strength (MPa)

6.00

5.00

4.00

3.00 0

30

60

90 Weathering Period (Days)

172

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Santoprene 101 55 V185

Elongation at Break Compound P9 500

Elongation at Break (%)

450

400

350

300 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P9 3.00

Modulus at 100% (MPa)

2.50

2.00

1.50

1.00

0.50 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

173

Compound P9

Modulus at 300% Compound P9 6.00

Modulus at 300% (MPa)

5.00

4.00

3.00

2.00 0

30

60

90

120

150

180

Weathering Period (Days)

174

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Nitrile Rubber

Compound P10 Table 1. Property changes after 6 months' exposure Property

Weathering Period Initial

After 6 months' exposure

Difference

% Change

83

91

7.5

9

Tensile Strength (MPa)

11.8

6. 7

-5.1

-43

Elongation at Break (%)

524

41 9

-104

-20

Modulus at 100% (MPa)

3.19

3.47

0.28

9

Modulus at 300% (MPa)

5.80

5.43

-0.37

-6

Hardness (IRHD) Tensile Properties

Compound P10 Table 2. Estimated changes after 6 months at 45 °C Property

% Change after 6 months of weathering

% Change after 6 months at 45 °C

% Change due to weathering effects alone

% Change due to 10 years in UK

9.0

6. 0

3

4

Tensile Strength (MPa)

-43.0

-2.5

-40

-5 8

Elongation at Break (%)

-19.9

-29.2

9

13

Modulus at 100% (MPa)

8.8

22.9

-14

-2 0

Modulus at 300% (MPa)

-6.4

33.1

-39

-5 6

Hardness (IRHD) Tensile Properties

© Copyright 2001 Rapra Technology Limited

175

Compound P10

Hardness Compound P10 94

92

Hardness (Micro-IRHD)

90

88

86

84

82

80 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Tensile Strength Compound P10 14.0 13.0

Tensile Strength (MPa)

12.0 11.0 10.0 9.0 8.0 7.0 6.0 5.0 0

30

60

90 Weathering Period (Days)

176

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Participant Compound - Nitrile Rubber

Elongation at Break Compound P10 600

Elongation at Break (%)

550

500

450

400

350

300 0

30

60

90

120

150

180

120

150

180

Weathering Period (Days)

Modulus at 100% Compound P10 5.00

Modulus at 100% (MPa)

4.50

4.00

3.50

3.00

2.50

2.00 0

30

60

90 Weathering Period (Days)

© Copyright 2001 Rapra Technology Limited

177

Compound P10

Modulus at 300% Compound P10 9.00

Modulus at 300% (MPa)

8.00

7.00

6.00

5.00

4.00 0

30

60

90

120

150

180

Weathering Period (Days)

178

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Figure 1 Surface cracking of natural rubber Compound C

Figure 2 Surface cracking of natural rubber Compound D

© Copyright 2001 Rapra Technology Limited

179

180

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Ozone Results

APPENDIX 3 OZONE RESULTS

© Copyright 2001 Rapra Technology Limited

181

Appendix 3

182

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Ozone Results

Table 1. Time to Grade 1 cracking (first cracking) at 50 pphm, h Compound reference

Strain level, % 5

10

15

20

30

A

4

4

4

4

4

B

360

4

4

4

4

C

2

2

2

2

2

D

8

8

2

2

2

E

24

2

2

2

2

F

2

2

2

2

2

G

4

4

4

4

4

H

72

8

4

4

4

J

#

#

#

#

57 6

K

#

#

38 4

288

28 8

P

48

2

2

2

2

R

240

456

48

4

4

W

#

#

240

19 2

96

N3

8

2

2

2

2

N7

#

#

#

576

57 6

P3

24

8

2

2

2

P4

360

48

24

16

8

P8

#

#

#

#

264

P10

#

408

72

72

24

# Cracking was never observed

© Copyright 2001 Rapra Technology Limited

183

184

0

100

200

300

400

500

600

700

A

B

C

D E F G H K

P

Figure 1

Compound References

J

R

W

N3

Ozone Resistance Results at 50 pphm

N7

P3

P4

P8

P10

5% Strain 10% Strain 15% Strain 20% Strain 30% Strain

Appendix 3

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Time to first cracking (hours)

Ozone Results

Table 2. Time to Grade 3 cracking at 50 pphm, h Compound reference

Strain level, % 5

10

15

20

30

A

360

#

552

36 0

21 6

B

#

#

600

432

36 0

C

432

216

72

72

72

D

360

360

72

72

48

E

48

8

24

24

24

F

24

8

24

24

48

G

72

16

8

8

8

H

72

48

16

16

16

P

216

192

192

192

12 0

R

#

45 6

96

24

24

N3

48

24

24

16

48

P3

72

24

16

16

16

P4

384

120

72

72

72

P8

#

#

#

#

264

P10

#

#

72

72

72

# Cracking was either never recorded or did not reach Grade 3 level

© Copyright 2001 Rapra Technology Limited

185

186

0

100

200

300

400

500

600

700

A

B

C D E F H

P

Figure 2

Compound References

G

R

N3

Ozone Resistance Results at 50 pphm

P3

P4

P8

P10

5% Strain 10% Strain 15% Strain 20% Strain 30% Strain

Appendix 3

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Time to Grade 3 cracking (hours)

Ozone Results

Table 3. Time to Grade 1 cracking (first cracking) at 200 pphm, h Compound reference

Strain level, % 5

10

15

20

30

A

4

2

2

2

2

B

4

2

2

2

2

C

2

2

2

2

2

D

4

2

2

2

2

J

#

#

#

552

36 0

K

#

#

#

168

12 0

L

144

144

96

72

48

M

#

#

#

192

14 4

N

#

14 4

#

96

96

P

2

2

2

2

2

R

48

16

2

2

2

W

#

96

72

48

48

P4

48

16

8

4

2

P8

#

#

19 2

48

16

P10

#

16

2

2

2

# Cracking was never observed

© Copyright 2001 Rapra Technology Limited

187

188

0

100

200

300

400

500

600

A

B

C D J K M

N

Figure 3

Compound References

L

P

R

Ozone Resistance Results at 200 pphm

W

P4

P8

P10

5% Strain 10% Strain 15% Strain 20% Strain 30% Strain

Appendix 3

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Time to first cracking (hours)

Ozone Results

Table 4. Time to Grade 3 cracking at 200 pphm, h Compound reference

Strain level, % 5

10

15

20

30

A

48

72

48

24

48

B

24

48

24

16

16

C

8

48

48

48

48

D

#

#

16

16

16

L

168

168

144

96

96

M

#

#

#

192

14 4

N

#

14 4

#

96

96

P

2

8

8

8

8

R

48

24

8

4

4

W

#

#

432

432

38 4

P4

72

24

24

24

16

P8

#

#

192

48

16

P10

#

24

8

8

8

# Cracking was either never recorded or did not reach Grade 3 level

© Copyright 2001 Rapra Technology Limited

189

190

0

50

100

150

200

250

300

350

400

450

500

A

B

C D L N

P

Figure 4

Compound References

M

R

Ozone Resistance Results at 200 pphm

W

P4

P8

P10

5% Strain 10% Strain 15% Strain 20% Strain 30% Strain

Appendix 3

Ageing of Rubber - Accelerated Weathering and Ozone Test Results

Time to Grade 3 cracking (hours)

Ozone Results

Compound P4 Grade 1 & 3 Cracking at 50 pphm predicted for grade 3

observed for grade 3

predicted for grade 1

observed for grade 1

40.0 35.0 30.0

Strain (%)

25.0 20.0 15.0 10.0 5.0 0.0 0

100

200

300

400

500

600

700

Time (hours)

Figure 5

Compound W Grade of Cracking at 200 pphm predicted for grade 1

observed for grade 1

40.0 35.0 30.0

Strain (%)

25.0 20.0 15.0 10.0 5.0 0.0 0

20

40

60

80

100

120

140

160

180

200

Time (hours)

Figure 6

© Copyright 2001 Rapra Technology Limited

191

Appendix 3

Compound P10 Grade 1 Cracking at 50 pphm predicted for grade 1

observed for grade 1

40.0 35.0 30.0

Strain (%)

25.0 20.0 15.0 10.0 5.0 0.0 0

100

200

300

400

500

600

700

Time (hours)

Figure 7

192

Ageing of Rubber - Accelerated Weathering and Ozone Test Results