ISO/TC 45/SC 2/WG 3 - Degradation tests

This document specifies the principles and procedures for estimating the thermal endurance of rubbers from the results of exposure to elevated temperatures for long periods. Two approaches are specified (see Introduction): — one using the Arrhenius equation; — the other using the WLF equation. In this document, the estimation of thermal endurance is based solely on the change in selected properties resulting from periods of exposure to elevated temperatures. The various properties of rubbers change at different rates on thermal ageing, hence comparison between different rubbers can only be made using the same properties.

This document specifies accelerated ageing or heat resistance tests on vulcanized or thermoplastic rubbers/thermoplastic elastomers. Four methods are possible, they are detailed in Clause 5.

This document specifies the procedures intended for use in estimating the resistance of vulcanized or thermoplastic rubbers to cracking when exposed, under static or dynamic tensile strain, to air containing a definite concentration of ozone, at a definite temperature and, if required, at a definite relative humidity in circumstances that exclude the effects of direct light. Visual observation and/or image analysis are used to evaluate the formation and growth of cracks. The changes in physical or chemical properties resulting from exposure can also be determined. Reference and alternative methods for determining the ozone concentration are described in ISO 1431-3.

This document describes methods of evaluating the resistance of vulcanized and thermoplastic rubbers to the action of liquids by measurement of properties of the rubbers before and after immersion in test liquids. The liquids concerned include current service liquids, such as petroleum derivatives, organic solvents and chemical reagents, as well as reference test liquids.

This document specifies a constant-stress flexometer test for the determination of the temperature rise and resistance to fatigue of vulcanized rubbers. Many rubber products, such as tyres and belts, are tested by subjecting them to an oscillating load with a constant peak stress amplitude. In order to obtain good correlation between accelerated tests and in-service exposure of these products, this document gives instructions for carrying out measurements under such conditions. This method is not applicable for rubber having a hardness greater than 85 IRHD.

This document specifies requirements for vulcanized rubbers in sheet form for use as standards in characterizing the effect of test liquids and service fluids. This document is not designed to provide formulations of elastomeric-product compositions for actual service.

ISO 4649:2017 specifies two methods for the determination of the resistance of rubber to abrasion by means of a rotating cylindrical drum device. The methods involve determination of the volume loss due to the abrasive action of rubbing a test piece over a specified grade of abrasive sheet. Method A is for a non-rotating test piece and method B is for a rotating test piece. For each method, the result can be reported as a relative volume loss or an abrasion resistance index. These test methods are suitable for comparative testing, quality control, specification compliance testing, referee purposes and research and development work. No close relation between the results of this abrasion test and service performance can be inferred. NOTE The abrasion loss is often more uniform using the rotating test piece because the whole surface of the test piece is in contact with the abrasive sheet over the duration of the test. However, there is considerable experience using the non-rotating test piece.

ISO 6943:2017 specifies a method for the determination of the resistance of vulcanized rubbers to fatigue under repeated tensile deformations, the test piece size and frequency of cycling being such that there is little or no temperature rise. Under these conditions, failure results from the growth of a crack that ultimately severs the test piece. The method is restricted to repeated deformations in which the test piece is relaxed to zero strain for part of each cycle. Analogous fatigue processes can occur under repeated deformations which do not pass through zero strain and also, in certain rubbers, under static deformation, but this document does not apply to these conditions. The method is believed to be suitable for rubbers that have reasonably stable stress-strain properties, at least after a period of cycling, and that do not show undue stress softening or set, or highly viscous behaviour. Materials that do not meet these criteria might present considerable difficulties from the points of view of both experiment and interpretation. For example, for a rubber that develops a large amount of set during the fatigue test, the test strain will be ill-defined and the fatigue life is likely to differ markedly under constant maximum load and constant maximum extension conditions; how the results for such a rubber should be interpreted or compared with those for other rubbers, has not been established by basic work. As a general guide, a rubber for which the set determined in accordance with 9.5 and 10.2 exceeds 10 % is likely to fall into this category. For this reason, the method is not considered suitable for most thermoplastic elastomers. Similar considerations apply with regard to other changes in elasticity behaviour during testing. This fatigue test is distinct from the flexometer tests described in the various parts of ISO 4666, where fatigue breakdown occurs under the simultaneous action of stress and temperature. Advantages over the De Mattia flex cracking and cut growth test (see ISO 132) include the following: - the test yields quantitative results which do not depend on operator interpretation and which can be recorded automatically; - the initial deformation is clearly defined and can readily be varied to suit different applications. Great caution is necessary in attempting to relate standard test results to service performance since the comparative fatigue resistance of different vulcanizates can vary according to the test conditions used and to the basis by which the results are compared. Guidance on the selection of test conditions and on the interpretation of results is given in Annex A.

ISO 132:2017 specifies a method of test intended for use in comparing the resistance of vulcanized or thermoplastic rubbers to the formation and growth of cracks, when subjected to repeated flexing on the De Mattia type machine. For determination of crack growth, an artificial cut is made in the test piece to initiate cut growth.

ISO 1431-3:2017 describes three types of method for the determination of ozone concentration in laboratory test chambers. Method A ? UV absorption: this is the reference method, and is used as the means of calibration for the alternative methods B and C. Method B ? Instrumental techniques: B1: electrochemical B2: chemiluminescence Method C ? Wet-chemical techniques: Procedure I Procedure II Procedure III

ISO 23337:2016 specifies a method for the determination of the resistance of rubber to abrasion using the Improved Lambourn test machine. The abrasion loss resulting from the slip caused by the difference in circumferential speed between a disc-shaped rubber test piece and an abrasive wheel, which are driven to rotate independently with their circumferences pressed against each other by a specified load, is determined. The test result can be reported as a volume loss per abrasion test time or running distance, and/or as an abrasion resistance index compared to a reference compound. As the Improved Lambourn test machine is capable of setting various abrasive conditions, such as slip rate, sliding speed and load, independently, this method is suitable for the evaluation of compounds for a range of rubber products, especially tyres, under a wide range of severity conditions. An example of the testing of tyre tread rubber is given in Annex A.

ISO 23233:2016 a method for the determination of the resistance of rubber to abrasion using a driven, vertical abrasive disc. The loss in mass on abrasion is determined through the slip caused by setting different slip angles and rotational speeds between a wheel-shaped rubber test piece and an abrasive disc which are rotating in planes at right angles to each other and pressed against each other with a specified load. The test result can be reported as the loss in mass per unit running distance and/or as an abrasion resistance index compared to a reference compound. ISO 23233:2016 is applicable to comparative testing, quality control, specification compliance testing, referee testing and research and development work. As the test device described is capable of setting each abrasion parameter, such as slip angle, rotational speed of the abrasive disc and load, independently, the method is suitable for carrying out a wide range of abrasion tests for various rubber products, especially tyres.

ISO 4665:2016 specifies methods for the exposure of vulcanized or thermoplastic rubbers to natural or artificial weathering and methods for the determination of changes in colour, appearance, and physical properties resulting from exposure.

ISO 4666-1:2010 establishes general principles for flexometer testing and defines the terms used. Flexometer testing makes possible predictions regarding the durability of rubbers in finished articles subject to dynamic flexing in service such as tyres, bearings, supports, V-belts, and cable-pulley insert rings. However, owing to the wide variations in service conditions, no simple correlation between the accelerated tests specified in the various parts of ISO 4666 and service performance can be assumed.

ISO 27727:2008 specifies a method for the determination of the fatigue crack growth rate of vulcanized rubber under repeated loading over an extended period of time. The crack starts from the tip of a cut made in the test piece before the test, and grows progressively until it finally becomes large enough for complete fracture to occur. Using a pure-shear test piece, measurements are made to monitor the crack growth under the cyclic loading in order to obtain the crack growth rate, i.e. the increase in crack length per cycle. Tests are carried out at various tearing energies by varying the strain energy density in the test piece. This is done by changing the strain amplitude.

ISO 4666-3:2016 specifies the flexometer test with constant-strain amplitude for the determination of the temperature rise and resistance to fatigue of vulcanized rubber. The flexometer specified is known as the Goodrich flexometer, but any other apparatus giving equivalent performance can be used. ISO 4666-3:2016 gives directions for carrying out measurements which make possible predictions regarding the durability of rubbers in finished articles subject to dynamic flexing in service, such as tyres, bearings, supports, V-belts, and cable-pulley insert rings. However, owing to the wide variations in service conditions, no simple correlation between the accelerated tests described in the various parts of this document and service performance can be assumed. The method is not recommended for rubber having a hardness greater than 85 IRHD.

ISO 23794:2015 provides guidance on the determination of the abrasion resistance of vulcanized and thermoplastic rubbers. It covers both solid and loose abrasives. The guidelines given are intended to assist in the selection of an appropriate test method and appropriate test conditions for evaluating a material and assessing its suitability for a product subject to abrasion. Factors influencing the correlation between laboratory abrasion testing and product performance are considered, but ISO 23794:2015 is not concerned with wear tests developed for specific finished rubber products, for example, trailer tests for tyres.

ISO 1817:2015 describes methods of evaluating the resistance of vulcanized and thermoplastic rubbers to the action of liquids by measurement of properties of the rubbers before and after immersion in test liquids. The liquids concerned include current service liquids, such as petroleum derivatives, organic solvents and chemical reagents, as well as reference test liquids.

ISO 11346:2014 specifies the principles and procedures for estimating the thermal endurance of rubbers from the results of exposure to elevated temperatures for long periods. Two approaches are specified: one using the Arrhenius relation; the other using the WLF equation. In ISO 11346:2014, the estimation of thermal endurance is based solely on the change in selected properties resulting from periods of exposure to elevated temperatures. The various properties of rubbers change at different rates on thermal ageing, hence comparisons between different rubbers can only be made using the same properties.

ISO 6914:2013 describes three methods for the measurement of the change of stress in a test piece at a given elongation for the purpose of determining the ageing characteristics of a rubber. Method A is intended for measurement under continuous strain conditions. Method B is the preferred method for measurement under intermittent strain conditions. In the case of both methods A and B, a stress relaxometer is used to record the stress at the temperature of ageing. Method C is an alternative to method B for measurement under intermittent strain conditions in which the test piece is removed from the ageing environment for measurement of the stress at standard laboratory temperature.

ISO 1431-1:2012 specifies procedures intended for use in estimating the resistance of vulcanized or thermoplastic rubbers to cracking when exposed, under static or dynamic tensile strain, to air containing a definite concentration of ozone and at a definite temperature in circumstances that exclude the effects of direct light.

ISO 132:2011 specifies a method of test intended for use in comparing the resistance of vulcanized or thermoplastic rubbers to the formation and growth of cracks, when subjected to repeated flexing on the De Mattia type machine. For determination of crack growth, an artificial cut is made in the test piece to initiate cut growth.

ISO 13226:2011 specifies requirements for vulcanized rubbers in sheet form for use as standards in characterizing the effect of test liquids and service fluids. Details of the individual standard reference elastomers are listed in the annexes. The compounding and preparation ensure that the property profile agrees sufficiently with that of the material group represented, while the simple formulation ensures reliable reproducibility. The specified property changes of the SRE when in contact with a fluid under specified conditions may be included as supplementary data in specifications for the fluid concerned. The standard is not designed to provide formulations of elastomeric-product compositions for actual service.

ISO 188:2011 specifies accelerated ageing or heat resistance tests on vulcanized or thermoplastic rubbers. Two methods are given: Method A: air-oven method using a cell-type oven or cabinet oven with low air speed and a ventilation of 3 to 10 changes per hour; Method B: air-oven method using a cabinet oven with forced air circulation by means of a fan and a ventilation of 3 to 10 changes per hour.

ISO 1817:2011 describes methods of evaluating the resistance of vulcanized and thermoplastic rubbers to the action of liquids by measurement of properties of the rubbers before and after immersion in test liquids. The liquids concerned include current service liquids, such as petroleum derivatives, organic solvents and chemical reagents, as well as reference test liquids.

ISO 4666-3:2010 specifies the flexometer test with constant-strain amplitude for the determination of the temperature rise and resistance to fatigue of vulcanized rubber. The flexometer specified is known as the Goodrich flexometer, but any other apparatus giving equivalent performance can be used. ISO 4666-3:2010 gives directions for carrying out measurements which make possible predictions regarding the durability of rubbers in finished articles subject to dynamic flexing in service such as tyres, bearings, supports, V-belts, and cable-pulley insert rings. However, owing to the wide variations in service conditions, no simple correlation between the accelerated tests described in the various parts of ISO 4666 and service performance can be assumed. The method is not recommended for rubber having a hardness greater than 85 IRHD.

ISO 4649:2010 specifies two methods for the determination of the resistance of rubber to abrasion by means of a rotating cylindrical drum device. The methods involve determination of the volume loss due to the abrasive action of rubbing a test piece over a specified grade of abrasive sheet. Method A is for a non-rotating test piece and method B for a rotating test piece. For each method, the result can be reported as a relative volume loss or an abrasion resistance index. Because factors such as the grade of abrasive sheet, the type of adhesive used in the manufacture of the sheet and contamination and wear caused by previous testing lead to variations in the absolute values of abrasion loss, all tests are comparative. Runs with a reference compound are included so that the results can be expressed either as a relative volume loss compared to a calibrated abrasive sheet or an abrasion resistance index compared to a reference compound. These test methods are suitable for comparative testing, quality control, specification compliance testing, referee purposes, and research and development work. No close relation between the results of this abrasion test and service performance can be inferred.

ISO 23794:2010 provides guidance on the determination of the abrasion resistance of vulcanized and thermoplastic rubbers. It covers both solid and loose abrasives. The guidelines given are intended to assist in the selection of an appropriate test method and appropriate test conditions for evaluating a material and assessing its suitability for a product subject to abrasion. Factors influencing the correlation between laboratory abrasion testing and product performance are considered, but this International Standard is not concerned with wear tests developed for specific finished rubber products, for example trailer tests for tyres.

ISO 23233:2009 specifies a method for the determination of the resistance of rubber to abrasion using a driven, vertical abrasive disc (the LAT 100: Laboratory Abrasion Tester 100). The loss in mass on abrasion is determined through the slip caused by setting different slip angles and rotational speeds between a wheel-shaped rubber test piece and an abrasive disc, rotating in planes at right angles to each other and pressed against each other with a specified load. The test result can be reported as the loss in mass per unit running distance and/or as an abrasion resistance index compared to a reference compound. This International Standard is applicable to comparative testing, quality control, specification compliance testing, referee testing and research and development work. As the test device described is capable of setting each abrasion parameter, such as slip angle, rotational speed of the abrasive disc and load, independently, the method is suitable for carrying out a wide range of abrasion tests for various rubber products, especially tyres.

ISO 4666-2:2008 specifies a rotary flexometer test for the determination of the temperature rise and resistance to fatigue of vulcanized rubbers under rotary shear loading. It allows the use of all four types of test conditions described in ISO 4666‑1. It gives directions for carrying out measurements which make possible predictions regarding the durability of rubbers in finished articles (tyres, bearings, supports, V‑belts, cable pulley insert rings and similar products subject to dynamic flexing in service). However, owing to the wide variations in service conditions, no simple correlation between the accelerated tests described in this part of ISO 4666 and service performance can be assumed.

ISO 6914:2008 describes three methods for the measurement of the change of stress in a test piece at a given elongation for the purpose of determining the ageing characteristics of a rubber. Method A is intended for measurement under continuous strain conditions. Method B is the preferred method for measurement under intermittent strain conditions. In the case of both methods A and B, a stress relaxometer is used to record the stress at the temperature of ageing. Method C is an alternative to method B for measurement under intermittent strain conditions in which the test piece is removed from the ageing environment for measurement of the stress at standard laboratory temperature. No agreement between the three methods should be inferred. The method used will depend on the purpose of the test.

ISO 4666-4:2007 specifies a constant-stress flexometer test for the determination of the temperature rise and resistance to fatigue of vulcanized rubbers. Many rubber products, such as tyres and belts, are tested by subjecting them to an oscillating load with a constant peak stress amplitude. In order to obtain good correlation between accelerated tests and in-service exposure of these products, this part of ISO 4666 gives instructions for carrying out measurements under such conditions. This method is not recommended for rubber having a hardness greater than 85 IRHD.

ISO 23337:2007 specifies a method for the determination of the resistance of rubber to abrasion using the Improved Lambourn test machine. The abrasion loss resulting from the slip caused by the difference in circumferential speed between a disc-shaped rubber test piece and an abrasive wheel, which are driven to rotate independently with their circumferences pressed against each other by a specified load, is determined. The test result can be reported as the volume loss per unit time or per unit running distance, and/or as an abrasion resistance index compared to a reference compound. As the Improved Lambourn test machine is capable of setting various abrasive conditions, such as slip rate, sliding speed and load, independently, this method is suitable for the evaluation, under a wide range of severity conditions, of compounds for a range of rubber products, especially tyres. An example of the testing of tyre tread rubber is given in an annex.

ISO 188:2007 specifies accelerated ageing or heat resistance tests on vulcanized or thermoplastic rubbers. Two methods are given: Method A: air-oven method using a cell-type oven or cabinet oven with low air speed and a ventilation of 3 to 10 changes per hour; Method B: air-oven method using a cabinet oven with forced air circulation by means of a fan and a ventilation of 3 to 10 changes per hour.

ISO 6943:2007 describes a method for the determination of the resistance of vulcanized rubbers to fatigue under repeated tensile deformations, the test piece size and frequency of cycling being such that there is little or no temperature rise. Under these conditions, failure results from the growth of a crack that ultimately severs the test piece. The method is restricted to repeated deformations in which the test piece is relaxed to zero strain for part of each cycle. Analogous fatigue processes can occur under repeated deformations which do not pass through zero strain and also, in certain rubbers, under static deformation, but this International Standard does not apply to these conditions. The method is believed to be suitable for rubbers that have reasonably stable stress-strain properties, at least after a period of cycling, and that do not show undue stress softening or set, or highly viscous behaviour. Materials that do not meet these criteria may present considerable difficulties from the points of view of both experiment and interpretation. For example, the method is not considered suitable for most thermoplastic elastomers.

ISO 4665:2006 specifies methods for the exposure of vulcanized or thermoplastic rubbers to natural or artificial weathering and methods for the determination of changes in colour, appearance and physical properties resulting from exposure.

ISO 13226:2005 specifies requirements for vulcanized rubbers in sheet form for use as standards in characterizing the effect of test liquids and service fluids. Details of the individual standard reference elastomers are listed in the annexes. The compounding and preparation ensure that the property profile agrees sufficiently with that of the material group represented, while the simple formulation ensures reliable reproducibility. The specified property changes of the SRE when in contact with a fluid under specified conditions may be included as supplementary data in specifications for the fluid concerned. The standard is not designed to provide formulations of elastomeric-product compositions for actual service.

ISO 132:2005 specifies a method of test intended for use in comparing the resistance of rubbers to the formation and growth of cracks, when subjected to repeated flexing on the De Mattia type machine. For determination of crack growth, an artificial cut is made in the test piece to initiate cut growth.

ISO 1817:2005 describes methods of evaluating the resistance of vulcanized rubbers to the action of liquids by measurement of properties of the rubbers before and after immersion in test liquids. The liquids concerned include current service liquids, such as petroleum derivatives, organic solvents and chemical reagents, as well as reference test liquids.

ISO 1431-1:2004 specifies procedures intended for use in estimating the resistance of vulcanized or thermoplastic rubbers to cracking when exposed, under static or dynamic tensile strain, to air containing a definite concentration of ozone and at a definite temperature in circumstances that exclude the effects of direct light.

ISO 6914:2004 describes three methods for measuring the change of stress in a rubber test piece at a given elongation for the purpose of determining the ageing characteristics of the rubber vulcanizate: one for measurement under continuous strain conditions and two for measurement under intermittent strain conditions. The necessary calibration schedule for this type of measurement is included in Annex A. No agreement between the three methods should be inferred; the method used will depend on the purpose of the test. Measurements at a single elevated ageing temperature may be used for quality control purposes as a measure of heat-ageing resistance. Measurements at a number of temperatures may be used for research and development purposes to estimate long-term ageing characteristics, in accordance with the procedures described in ISO 11346.

ISO 11346:2004 specifies the principles and procedures for estimating the thermal endurance of rubbers from the results of exposure to elevated temperatures for long periods. Two approaches are specified: one using the Arrhenius relation; the other using the WLF equation. The estimation of thermal endurance is based solely on the change in selected properties resulting from periods of exposure to elevated temperatures. The various properties of rubbers change at different rates on thermal ageing, hence comparisons between different rubbers can only be made using the same properties.

ISO 23794:2003 provides guidance on the determination of the abrasion resistance of vulcanized and thermoplastic rubbers. It covers both solid and loose abrasives. The guidelines given in ISO 23794:2003 are intended to assist in the selection of an appropriate test method and appropriate test conditions for evaluating a material and assessing its suitability for a product subject to abrasion. Factors influencing the correlation between laboratory abrasion testing and product performance are considered, but this International Standard is not concerned with wear tests developed for specific finished rubber products, for example trailer tests for tyres.

This International Standard specifies two methods for the determination of the resistance of rubber to abrasion by means of a rotating cylindrical drum device. The methods involve determination of the volume loss due to the abrasive action of rubbing a test piece over a specified grade of abrasive sheet. Method A is for a non-rotating test piece and method B for a rotating test piece. For each method, the result can be reported as a relative volume loss or an abrasion resistance index. Because factors such as the grade of abrasive sheet, the type of adhesive used in the manufacture of the sheet and contamination and wear caused by previous testing lead to variations in the absolute values of abrasion loss, all tests are comparative. Runs with a reference compound are included so that the results may be expressed either as a relative volume loss compared to a calibrated abrasive sheet or an abrasion resistance index compared to a reference compound. These test methods are suitable for comparative testing, quality control, specification compliance testing, referee purposes, and research and development work. No close relation between the results of this abrasion test and service performance can be inferred.