ISO/TC 45/SC 2/WG 2 - Visco-elastic properties

This document specifies a method for determining selected vulcanization characteristics of a rubber compound by means of a rotorless curemeter. An introduction to the use of curemeters is given in ISO 6502‑1.

This document describes two methods for measuring stress in tension under non-isothermal conditions. — Method A: The thermal stress is measured for various pre-strain and temperature conditions as a function of time. — Method B: The change of stress is measured in a test piece at a given strain and under variation of temperature at a given heating rate as a function of temperature. In this way, the determination of the thermal-mechanical behaviour of a rubber can be accelerated, e.g. for the purpose of comparative testing of aging or estimating the upper limit of the operating temperature. The measurement device, which is equipped with a suitable heating chamber, is used to record the stress as a function of time or temperature until the sample breaks or the stress has approached zero or for a certain time.

This document gives guidance on the determination of dynamic properties of vulcanized and thermoplastic rubbers. It includes both free- and forced-vibration methods carried out on both materials and products. It does not cover rebound resilience or cyclic tests in which the main objective is to fatigue the rubber.

This document specifies a method for the determination of the green strength of raw rubber or unvulcanized rubber compounds using a tensile stress-strain test, the test pieces being prepared following standard test conditions or cut from calendered sheets.

This document specifies a method for determining the glass transition temperature, Tg, of vulcanized rubbers in the hardness range from 30 IRHD to 80 IRHD. The dynamic properties are measured via temperature sweep in sinusoidal deformation at a defined strain and frequency and Tg is determined from the peak in the tan δ versus temperature curve. Glass transition temperature, Tg, determined in this way serves the purpose of a guideline to the service temperature of the material.

This document specifies a method for determining the pre-vulcanization characteristics of compounded rubber. The pre-vulcanization characteristics determined by this method provide a means of estimating how long compounded rubber can be maintained at high temperatures and remain processable.

This document specifies methods for the determination of the compression set characteristics of vulcanized and thermoplastic rubbers at ambient (one method) or elevated temperatures (three methods, A, B, and C, depending on the way the test piece is released at the end of the test). The methods are intended to measure the ability of rubbers of hardness within the range 10 IRHD to 95 IRHD to retain their elastic properties at specified temperatures after prolonged compression at constant strain (normally 25 %) under one of the alternative sets of conditions described. For rubber of nominal hardness 80 IRHD and above, a lower compression strain is used: 15 % for a nominal hardness from 80 IRHD to 89 IRHD and 10 % for a nominal hardness from 90 IRHD to 95 IRHD. NOTE 1 When rubber is held under compression, physical or chemical changes that prevent the rubber returning to its original dimensions after release of the deforming force can occur. The result is a set, the magnitude of which depends on the time and temperature of compression as well as on the time, temperature, and conditions of recovery. At elevated temperatures, chemical changes become increasingly more important and lead to a permanent set. NOTE 2 Short-time compression set tests, typically for 24 h, at elevated temperatures are commonly used as a measure of the state of cure, a means of material classification, and a specification to ensure the quality of a compound. Longer tests, typically for 1 000 h, at elevated temperatures take account of the effect of ageing and are often used to predict service performance, including that of sealing materials. Short-time tests at ambient temperature show mainly the effect of physical changes (re-orientation of the molecular chains and the fillers).

This document specifies two methods for the determination of the compression set characteristics of vulcanized and thermoplastic rubbers at low temperatures. Method 1 derives from the methodology used in ISO 815-1. Method 2 uses a specified testing device, allowing to measure and record the test piece thickness during recovery. Due to the load applied during recovery in method 2, no correlation can be established between the results given by both methods. NOTE When rubber is held under compression, physical or chemical changes that prevent the rubber returning to its original dimensions after release of the deforming force can occur. The result is a set, where the magnitude of which depends on the time and temperature of compression as well as on the time, temperature, and conditions of recovery. At low temperatures, changes resulting from the effects of glass hardening or crystallization become predominant and, since these effects are reversed by raising the temperature, therefore, the measurements are always taken at the test temperature.

This document specifies two procedures for determining the decrease in counterforce exerted by a test piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and maintained thus at a predetermined test temperature. The counterforce can be determined either by means of a continuous-measurement system or by a discontinuous-measurement one. Two test methods are specified, method A and method B. In method A the compression and all measurements of counterforce are made at test temperature and in method B the compression and all measurements of counterforce are made at standard laboratory temperature. Method A and method B do not give the same results, as in method B the shrinkage of the material from the test temperature to standard laboratory temperature is included in the result. Two forms of test piece are specified in this document: cylindrical test pieces and rings. Comparison of results is valid only when made on test pieces of similar size and shape. The use of ring test pieces is particularly suitable for the determination of stress relaxation in liquid environments. This document deals only with testing at constant ambient or elevated temperature. Testing at temperatures below standard laboratory temperature is not specified. The methods have been used for low‑temperature testing, but their reliability under these conditions is not proven.

This document specifies two methods for determining the decrease in counterforce exerted by a test piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and then undergoes temperature cycling. Method A: The temperature is cycled at intervals between a high temperature for ageing and a low temperature for checking the sealing force at this low temperature. Method B: The temperature is cycled continuously between a high temperature and a low temperature to introduce thermal stress in the test piece. The counterforce is determined by means of a continuous-measurement system. Two forms of test pieces are specified in this document: cylindrical test pieces and rings. Comparison of results is valid only when made on test pieces of similar size and shape. The use of ring test pieces is particularly suitable for the determination of stress relaxation in liquid environments.

This document specifies a method for the determination of creep in vulcanized rubber continuously subjected to compressive or to shear forces. The standard cannot be used for intermittent deformation of rubber.

This document specifies a number of methods of determining the dimensional changes in test pieces of vulcanized or thermoplastic rubber during and after tensile loading for relatively short periods under constant elongation or constant loading. The constant-elongation test is intended to measure the ability of rubbers to retain their elastic properties after extension, at a standard laboratory temperature, to a specified strain which is maintained for a specified time at the same or at a specified higher temperature and then released at the test temperature or at the standard laboratory temperature. The constant-load test specifies a method for the determination of elongation, creep and tension set of rubbers subjected to a constant load at standard laboratory temperature. The test methods are intended to measure the elastic properties of rubber in the hardness range 20 IRHD to 94 IRHD. The creep measurement is not intended for product design or the evaluation of low-creep materials. For these, ISO 8013 applies, and there is no agreement between the results of this test and those of ISO 8013. NOTE The constant-load test is primarily intended for the measurement of state of cure and the quality control of thin-walled products. An increase in the state of cure or degree of crosslinking is usually reflected in a decrease in set, creep or elongation.

This document specifies a method for determining selected vulcanization characteristics of a rubber compound by means of an oscillating disc curemeter. The introduction to the use of curemeters is described in ISO 6502‑1.

This document provides an introduction to the determination of vulcanization characteristics of rubber compounds by means of curemeters.

This document specifies a method for the rapid determination of the plasticity of raw rubber and unvulcanized compounded rubber. It is applicable to the determination of the plasticity retention index (PRI) as specified in ISO 2930.

ISO/TS 289-4 specifies a method of use of a shearing-disc viscometer for measuring the Mooney stress-relaxation rate (MSR) of uncompounded or compounded, unvulcanized rubbers, characterizing the elastic response of those materials next to the viscous response as measured by the Mooney viscosity. The intended use of this document is on quality control measurements.

ISO 4662:2017 specifies two methods for determining the rebound resilience of rubber the hardness of which lies between 30 IRHD and 85 IRHD. They are the pendulum method and the tripsometer method. With the pendulum method, a mass with a spherical end impacts a flat test piece, firmly held but free to bulge. The kinetic energy of the impacting mass is measured immediately before and after impact. With the tripsometer method, a flat test piece is impacted by a hemisphere mounted on the periphery of a disc which is supported on an axle and caused to rotate by an off-axis mass. The kinetic energy of the impacting mass is measured immediately before and after impact.

ISO 289-3:2015 specifies a method for determining the Delta Mooney value of non-pigmented, oil-extended emulsion-polymerized styrene-butadiene rubber.

ISO 289-1:2015 specifies a method using a shearing-disc viscometer for measuring the Mooney viscosity of uncompounded or compounded rubbers.

ISO 4664-2:2006 specifies methods, using a torsion pendulum, of determining the dynamic properties in shear, that is the shear modulus and mechanical damping, of vulcanized or thermoplastic rubbers over a wide temperature range at low frequencies in the range 0,1 Hz to 10 Hz and at comparatively low strains of less than 5 x 10-4.

ISO 7323:2006 specifies a method using the parallel-plate plastometer for the determination of the plasticity number and recovery number of uncompounded, compounded and reclaimed stocks of unvulcanized rubbers and rubber-like materials.

This document specifies a method for determining selected vulcanization characteristics of a rubber compound by means of a rotorless curemeter. The introduction to the use of curemeters is given in ISO 6502‑1.

ISO 12493:2017 specifies a method for measuring the stress in tension which is developed in vulcanized rubber when it is heated (thermal stress). The thermal stress is measured for various pre-strain and temperature conditions as a function of time.

ISO 289-2:2016 specifies a method for determining the pre-vulcanization characteristics of compounded rubber. The pre-vulcanization characteristics determined by this method provide a means of estimating how long compounded rubber can be maintained at high temperatures and remain processable.

ISO 6502:2016 provides guidance on the determination of vulcanization characteristics of rubber compounds by means of curemeters.

ISO 815-2:2014 specifies two methods for the determination of the compression set characteristics of vulcanized and thermoplastic rubbers at low temperatures. Method 1 derives from the methodology used in ISO 815‑1. Method 2 uses a specified testing device, allowing to measure and record the test piece thickness during recovery. Due to the load applied during recovery in method 2, no correlation can be established between the results given by both methods.

ISO 815-1:2014 specifies methods for the determination of the compression set characteristics of vulcanized and thermoplastic rubbers at ambient (one method) or elevated temperatures (three methods, A, B, and C, depending on the way the test piece is released at the end of the test). The methods are intended to measure the ability of rubbers of hardness within the range 10 IRHD to 95 IRHD to retain their elastic properties at specified temperatures after prolonged compression at constant strain (normally 25 %) under one of the alternative sets of conditions described. For rubber of nominal hardness 80 IRHD and above, a lower compression strain is used: 15 % for a nominal hardness from 80 IRHD to 89 IRHD and 10 % for a nominal hardness from 90 IRHD to 95 IRHD.

ISO 289-1:2014 specifies a method, using a shearing-disc viscometer, for measuring the Mooney viscosity of uncompounded or compounded rubbers.

ISO 2285:2013 specifies a number of methods of determining the dimensional changes in test pieces of vulcanized or thermoplastic rubber during and after tensile loading for relatively short periods under constant elongation or constant loading. The constant-elongation test is intended to measure the ability of rubbers to retain their elastic properties after extension, at a standard laboratory temperature, to a specified strain which is maintained for a specified time at the same or at a specified higher temperature and then released at the test temperature or at the standard laboratory temperature. The constant-load test specifies a method for the determination of elongation, creep and tension set of rubbers subjected to a constant load at standard laboratory temperature. The test methods are intended to measure the elastic properties of rubber in the hardness range 20 IRHD to 94 IRHD. The creep measurement is not recommended for product design or the evaluation of low-creep materials. For these, reference should be made to ISO 8013.

ISO 3384-2:2012 specifies two methods for determining the decrease in counterforce exerted by a test piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and then undergoes temperature cycling. Method A: The temperature is cycled at intervals between a high temperature for ageing and a low temperature for checking the sealing force at this low temperature. Method B: The temperature is cycled continuously between a high temperature and a low temperature to introduce thermal stress in the test piece. The counterforce is determined by means of a continuous-measurement system.

ISO 8013:2012 specifies a method for the determination of creep in vulcanized rubber continuously subjected to compressive or to shear forces. The standard cannot be used for intermittent deformation of rubber.

ISO 13145:2012 describes a method for the determination of the viscosity and stress relaxation of raw or compounded rubber under specified conditions. The viscosity determination consists of a constant strain, temperature and frequency test in which the elastic and the loss components of the complex shear modulus can be determined. The determination of stress relaxation consists of a constant static strain and temperature test in which the torque decrease can be determined.

ISO 3384-1-2011 specifies two methods for determining the decrease in counterforce exerted by a test piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and maintained thus at a predetermined test temperature. The counterforce can be determined either by means of a continuous-measurement system or by a discontinuous-measurement one. Two forms of test piece are permitted: cylindrical test pieces and rings. Different shapes and sizes of test piece give different results, and comparison of results should be limited to test pieces of similar size and shape. The use of ring test pieces is particularly suitable for the determination of stress relaxation in liquid environments. ISO 3384-1 deals only with testing at constant ambiant or elevated temperature. Testing at temperatures below standard laboratory temperature is not specified. The methods have been used for low-temperature testing, but their reliability under these conditions is not proven.

ISO 4664-1:2011 provides guidance on the determination of dynamic properties of vulcanized and thermoplastic rubbers. It includes both free- and forced-vibration methods carried out on both materials and products. It does not cover rebound resilience or cyclic tests in which the main objective is to fatigue the rubber.

ISO 4662:2009 specifies two methods for determining the rebound resilience of rubber the hardness of which lies between 30 IRHD and 85 IRHD. They are the pendulum method and the tripsometer method. With the pendulum method, a mass with a spherical end impacts a flat test piece, firmly held but free to bulge. The kinetic energy of the impacting mass is measured immediately before and after impact. With the tripsometer method, a flat test piece is impacted by a hemisphere mounted on the periphery of a disc which is supported on an axle and caused to rotate by an off-axis mass. The kinetic energy of the impacting mass is measured immediately before and after impact.

ISO 3417:2008 specifies a method for determining selected vulcanization characteristics of a rubber compound by means of an oscillating disc curemeter. The use of the curemeter is described in ISO 6502.

ISO 815-2:2008 specifies a method for the determination of the compression set characteristics of vulcanized and thermoplastic rubbers at low temperatures. The method is intended to measure the ability of rubbers of hardness within the range 10 IRHD to 95 IRHD to retain their elastic properties at specified temperatures after prolonged compression at constant strain (normally 25 %) under one of the alternative sets of conditions described. For rubber of nominal hardness 80 IRHD and above, a lower compression strain is used: 15 % for a nominal hardness from 80 IRHD to 89 IRHD and 10 % for a nominal hardness from 90 IRHD to 95 IRHD. NOTE When rubber is held under compression, physical or chemical changes can occur that prevent the rubber returning to its original dimensions after release of the deforming force. The result is a set the magnitude of which depends on the time and temperature of compression as well as on the time and temperature of recovery. At low temperatures, changes resulting from the effects of glass hardening or crystallization become predominant and, since these effects are reversed by raising the temperature, it is necessary for all measurements to be undertaken at the test temperature.

ISO 815-1:2008 specifies methods for the determination of the compression set characteristics of vulcanized and thermoplastic rubbers at ambient or elevated temperatures. The methods are intended to measure the ability of rubbers of hardness within the range 10 IRHD to 95 IRHD to retain their elastic properties at specified temperatures after prolonged compression at constant strain (normally 25 %) under one of the alternative sets of conditions described. For rubber of nominal hardness 80 IRHD and above, a lower compression strain is used: 15 % for a nominal hardness from 80 IRHD to 89 IRHD and 10 % for a nominal hardness from 90 IRHD to 95 IRHD. NOTE 1 When rubber is held under compression, physical or chemical changes can occur that prevent the rubber returning to its original dimensions after release of the deforming force. The result is a set the magnitude of which depends on the time and temperature of compression as well as on the time and temperature of recovery. At elevated temperatures, chemical changes become increasingly more important and lead to a permanent set. NOTE 2 Short-time compression set tests, typically for 22 h, at elevated temperatures are commonly used as a measure of the state of cure, a means of material classification and a specification to ensure the quality of a compound. Longer tests, typically for 1 000 h, at elevated temperatures take account of the effect of ageing and are often used to predict service performance, including that of sealing materials. Short-time tests at ambient temperature show mainly the effect of physical changes (re-orientation of the molecular chains and the fillers).

ISO 2285:2007 specifies a number of methods of determining the dimensional changes in test pieces of vulcanized or thermoplastic rubber during and after tensile loading for relatively short periods under constant elongation or constant loading. The constant-elongation test is intended to measure the ability of rubbers to retain their elastic properties after extension, at a standard laboratory temperature, to a specified strain which is maintained for a specified time at the same or at a specified higher temperature and then released at the test temperature or at the standard laboratory temperature. The constant-load test specifies a method for the determination of elongation, creep and tension set of rubbers subjected to a constant load at standard laboratory temperature. The test methods are intended to measure the elastic properties of rubber in the hardness range 20 IRHD to 94 IRHD. The creep measurement is not recommended for product design or the evaluation of low-creep materials. For these, reference should be made to ISO 8013. NOTE The constant-load test is primarily intended for the measurement of state of cure and the quality control of thin-walled products. An increase in the state of cure or degree of crosslinking is usually reflected in a decrease in set, creep or crosslinking.

ISO 9026:2007 specifies a method for the determination of the green strength of raw rubber or unvulcanized rubber compounds using a tensile stress-strain test, the test pieces being prepared following standard test conditions or cut from calendered sheets.

ISO 2007:2007 specifies a method for the rapid determination of the plasticity of raw rubber and unvulcanized compounded rubber. It is applicable to the determination of the plasticity retention index (PRI) as specified in ISO 2930, Rubber, raw natural -- Determination of plasticity retention index (PRI).

ISO 8013:2006 specifies a method for the determination of creep in rubber continuously subjected to compressive or to shear forces. The standard cannot be used for intermittent deformation of rubber.

ISO 289-1:2005 specifies a method, using a shearing-disc viscometer, for measuring the Mooney viscosity of uncompounded or compounded rubbers.

ISO 289-4:2003 specifies a method of use of a shearing-disc viscometer for measuring the Mooney stress-relaxation rate (MSR) of uncompounded or compounded unvulcanized rubbers, characterizing the elastic response of those materials next to the viscous response as measured by the Mooney viscosity.

The test consists of determining how the Mooney viscosity of the rubber compound changes with running time at a specified temperature relevant to the process for which the compound is to be used. The time at which the Mooney viscosity has increased by a specified number of units is recorded. The pre-vulcanization characteristics determined by this method provide a means of estimating how long compounded rubber can be maintained at high temperatures and remain processable.

Applies to uncompounded or compounded rubbers. The torque which has to be applied under specified conditions in order to rotate a metal disc in a cylindrical chamber formed from mating dies filled with rubber is measured. The resistance offered by the rubber to this rotation is expressed in arbitrary units as the Mooney viscosity of the test piece.