ISO/TC 45/SC 2 - Testing and analysis

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 describes two methods for identification of antidegradants (antioxidants, antiozonants and stabilizers) which can be present in raw rubber, unvulcanized compounded rubber, or rubber products, by thin layer chromatography. Method A is a simplified method that provides for the identification of known materials and can be used to check the presence or absence of a particular antidegradant which is expected to be present. Method B is a more detailed method that enables a greater degree of separation of the spots to be obtained and therefore can be used to detect and identify an unknown antidegradant. Antidegradants to which these methods are applicable include phosphited polyalkyl phenols, substituted bisphenols, secondary amines, substituted cresols and substituted p-phenylenediamines. Examination for other types of antidegradants is possible under the same condition when there is a standard chromatogram.

This document specifies an atomic absorption spectrometric method for the determination of the copper content of rubbers. The method is applicable to raw rubber and rubber products having copper contents above 1 ppm. Copper contents below this limit can be determined, provided that suitable adjustments are made to either the mass of the test portion or to the concentrations of the solutions used, or both. The use of the standard additions method can lower the bottom limit of detection.

This document specifies an atomic absorption spectrometric method for the determination of the manganese content of rubbers. The method is applicable to raw rubber and rubber products having manganese content above 0,5 ppm. Manganese contents below this limit can be determined, provided that suitable adjustments are made either to the mass of the test portion or to the concentrations of the solutions used, or both. The use of the standard additions method can lower the bottom limit of detection.

This document specifies three methods for the determination of the permeability to gases of vulcanized or thermoplastic rubber under a differential partial pressure. The three methods specified are as follows: — a pressure sensor method (using vacuum): for determining the gas transmission rate, gas permeability coefficient, gas diffusion coefficient and gas solubility coefficient; — a simplified sensor method (using applied pressure): for determining the gas permeability coefficient only; — a gas-chromatographic method: for determining the gas transmission rate and gas permeability coefficient. These methods apply to vulcanized and thermoplastic rubbers of hardness not less than 35 IRHD (international rubber hardness degrees) and to both single gases and mixtures of gases.

This document specifies a quantitative test method to determine the 2-mercaptobenzothiazole content in rubber and rubber products by high performance liquid chromatography (HPLC). This document delivers a method for quantifying 2-mercaptobenzothiazole in rubber products for a better selection of curing conditions. This document provides a method to follow the curing of rubber with sulfur- and benzothiazole-based accelerators using a chemical measurement which is complementary to the classical rheometric technique.

This document specifies a method for the determination of the total sulfur content of raw rubber and unvulcanized or vulcanized rubber compounds by ion chromatography following the preparation of a sample solution using either a tubular furnace combustion or an oxygen combustion flask method. The tubular furnace combustion method is applicable for rubbers with sulfur content less than 0,1 % as it is possible that the oxygen combustion flask method will not give sufficiently accurate results. The oxygen combustion flask method is not applicable to rubbers containing a metal salt that forms an insoluble metal sulfate, such as barium sulfate (CAS 7727‑43‑7).

This document describes the method of determination of both major and trace levels of metal contents in rubber — raw, vulcanized — by ICP-OES.

This document specifies a method for the determination of the static adhesion of textile cord to vulcanized rubber using the H-pull test. It is applicable to cords made from natural or man-made fibres. The property levels obtained with this method are affected considerably by the history of the cord and the rubber compound. The method yields data, however, on which a judgement as to the service quality of the material can be based. The method is primarily intended for use with tyre cord. However, it can be applied, if desired, to similar cords for use in other rubber products, but it is limited to cords of linear density not exceeding 800 mg/m (tex).

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 the determination of the tendency of vulcanized or thermoplastic rubbers to adhere to and to corrode metals when exposed to a specified test environment.

This document describes a procedure for the determination of the following antidegradants in vulcanized rubbers: — aminoketone group; — naphthylamine group; — diphenylamine group; — p-phenylenediamine; — monophenol group. The groups of antidegradants are summarized in Table A.1 with the chemical names, the abbreviated terms and the CAS registry numbers. Extender oils, when present, can interfere. For poly-2,2,4-trimethyl-1,2-dihydroquinoline, the method provides only an approximation because of its polymeric nature.

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 static procedure, known as the Gehman test, for determining the relative stiffness characteristics of vulcanized or thermoplastic rubbers over a temperature range from room temperature to approximately −120 °C.

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 a method of test for measuring the force required to separate, by stripping, two plies of fabric bonded with rubber, or a rubber layer and a fabric ply bonded together. The method is applicable when the ply surfaces are approximately plane or when they are in the form of a cylinder having an internal diameter greater than approximately 50 mm. The method is not applicable when the ply surfaces contain sharp bends, angles or other gross irregularities which cannot be excluded when cutting out test pieces. This document does not apply to coated fabrics, which are tested in accordance with ISO 2411, or textile conveyor belts, which are tested in accordance with ISO 252.

This document specifies a test based on hardness measurements for determining the progressive stiffening of rubber with time, caused by crystallization. It is limited to materials having an initial hardness at a test temperature of from 10 IRHD to 85 IRHD. The method is applicable to raw, unvulcanized (compounded) and vulcanized rubber. It is mainly of interest for rubber with a marked crystallization tendency at temperatures experienced in cold climates, such as chloroprene and natural rubber. The method is not applicable to fast-crystallizing materials which crystallize to a considerable degree within the timespan of 15 min used for conditioning at test temperature.

This document specifies a method for the identification of polymers, or blends of polymers, in raw rubbers and in vulcanized or unvulcanized compounds from pyrograms (pyrolysis-gas chromatographic patterns) obtained under the same conditions. This allows qualitative identification of single rubbers or blends, with exceptions discussed below. This document is not intended for quantitative analysis. The method applies first and foremost to single polymers. When the pyrogram indicates a characteristic hydrocarbon, the method is also applicable to blends. For details, see Clause 5. The method can be also applicable to other types of polymer when verified by the analyst in each particular case. NOTE The use of this document pre-supposes sufficient working knowledge of the principles and techniques of gas chromatography to enable the analyst to carry out the operations described and to interpret the results correctly.

This document specifies three methods for estimating the staining of organic finishes (subsequently referred to as "organic material") by vulcanized or thermoplastic rubber, as defined in Clause 3: — method A: contact staining and migration staining; — method B: extraction staining; — method C: penetration staining;

This document provides a qualitative method for the identification of rubbers by their pyrolysis products using tandem gas-chromatography/mass spectrometry. The method applies to rubbers in the raw state and to unvulcanized and vulcanized compounds. Compounds can be based on a single rubber or a blend of two or more rubbers. Where the level of a particular rubber in a blend is A non-restrictive list of rubbers is given in Clause 4.

This document specifies methods for the determination of chlorine and/or bromine present in raw rubber as well as vulcanized or unvulcanized rubber compounds. The methods are applicable to natural rubbers and to the following synthetic rubbers: isoprene, styrene-butadiene, butadiene, butyl, halogenated butyl, nitrile, ethylene-propylene, chloroprene and epichlorohydrin.

This document specifies an atomic absorption spectrometric method for the determination of the zinc content of rubbers. The method is applicable to raw rubber and rubber products having zinc contents at a minimum of 0,05 % (mass fraction). Zinc contents below this limit can be determined, provided that suitable adjustments are made to the mass of the test portion and/or to the concentrations of the solutions used. The use of the standard additions method might lower the bottom limit of detection.

This document specifies an atomic absorption spectrometric method for the determination of the lead content of rubbers. The method is applicable to raw rubber and rubber products. There is no limit to the concentration of lead that can be determined. High or low concentrations can be determined, provided that suitable adjustments are made to the mass of the test portion and/or the concentration of the solutions used. The use of the standard-additions method might lower the bottom limit of detection.

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 a method for the determination of the temperature-retraction characteristics of stretched vulcanized rubber. This document does not cover thermoplastic rubbers, as many thermoplastic elastomers have a yield point in the range of 5 % to 20 % elongation.

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 requirements for tensile-testing systems operating at constant rate of traverse and suitable for testing rubbers, plastics and adhesives, although any one system might only be applicable to a narrower range of materials. It also covers such systems when used for flexural, shear and compression tests.

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 chromatographic methods for the determination of the inorganic free sulfur (Sx) not consumed during the vulcanization of the rubber. This method is used primarily to compare the free sulfur content in different samples. NOTE 1 In this document, "free sulfur" is used instead of "inorganic free sulfur". NOTE 2 The residual curing agent containing sulfur is not concerned by this measure.

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 the determination of the adhesive strength of a vulcanized or thermoplastic rubber bonded to a rigid substrate, using a test piece comprising a strip of rubber bonded to a single plate of rigid material. The test is carried out at a peel angle of 90°. The method is applicable primarily to test pieces prepared in the laboratory under standard conditions, such as can be used to provide data for the choice of rubber compounds or adhesive systems, the development of such materials and the control of manufacturing processes. This method is not suitable for high-hardness rubbers, typically above 85 IRHD.

This document specifies a method for the determination of the volume and the surface resistivity of vulcanized or thermoplastic rubbers. The method can be applied to materials with a resistivity from 101 Ω⋅m to 1017 Ω⋅m.

This document specifies a method for the determination of the insulation resistance of vulcanized and thermoplastic rubbers without discrimination between the volume and surface resistances involved. This method is applicable only to the test pieces with a resistance greater than 108 Ω. NOTE Methods of test for test pieces with a lower resistance are described in ISO 1853 and ISO 2878. Because the test pieces are simply and easily prepared, this method is particularly useful for rapidly determining values which will give a general indication of quality when great accuracy is not required.

This document specifies a method for the determination of the gas transmission rate and gas permeability coefficient of vulcanized or thermoplastic rubber under conditions in which the overall pressure on each side of the rubber test piece is the same, using gas chromatography to determine the quantity of gas that permeates through the rubber. The method applies to vulcanized and thermoplastic rubbers of hardness not less than 35 IRHD (international rubber hardness degrees) and to both single gases and mixtures of gases.

This document specifies a method of preparing samples from vulcanized rubber for use in chemical tests.

This document specifies an atomic absorption spectrometric method for the determination of the magnesium content of natural rubber latex concentrate, raw natural rubber and products made from natural rubber.

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 provides guidance on the determination of the hardness of vulcanized and thermoplastic rubbers. It is intended to provide an understanding of the significance of hardness as a material property and to assist in the selection of an appropriate test method.

This document specifies four methods for the determination of the hardness of vulcanized or thermoplastic rubbers on flat surfaces (standard-hardness methods) and four methods for the determination of the apparent hardness of curved surfaces (apparent-hardness methods). The hardness is expressed in international rubber hardness degrees (IRHD). The methods cover the hardness range from 10 IRHD to 100 IRHD. These methods differ primarily in the diameter of the indenting ball and the magnitude of the indenting force, these being chosen to suit the particular application. The range of applicability of each method is indicated in Figure 1. This document does not specify a method for the determination of hardness by a pocket hardness meter, which is described in ISO 48-5. This document specifies the following four methods for the determination of standard hardness. — Method N (normal test) is appropriate for rubbers with a hardness in the range 35 IRHD to 85 IRHD, but can also be used for hardnesses in the range 30 IRHD to 95 IRHD. — Method H (high-hardness test) is appropriate for rubbers with a hardness in the range 85 IRHD to 100 IRHD. — Method L (low-hardness test) is appropriate for rubbers with a hardness in the range 10 IRHD to 35 IRHD. — Method M (microtest) is essentially a scaled-down version of the normal test method N, permitting the testing of thinner and smaller test pieces. It is appropriate for rubbers with a hardness in the range 35 IRHD to 85 IRHD, but can also be used for hardnesses in the range 30 IRHD to 95 IRHD. NOTE 1 The value of the hardness obtained by method N within the ranges 85 IRHD to 95 IRHD and 30 IRHD to 35 IRHD might not agree precisely with that obtained using method H or method L, respectively. The difference is not normally significant for technical purposes. NOTE 2 Because of various surface effects in the rubber and the possibility of slight surface roughness (produced, for example, by buffing), the microtest might not always give results agreeing with those obtained by the normal test. This document also specifies four methods, CN, CH, CL and CM, for the determination of the apparent hardness of curved surfaces. These methods are modifications of methods N, H, L and M, respectively, and are used when the rubber surface tested is curved, in which case there are two possibilities: a) the test piece or product tested is large enough for the hardness instrument to rest upon it; b) the test piece or product tested is small enough for both the test piece and the instrument to rest upon a common support. A variant of b) would be where the test piece rests upon the support surface of the instrument. Apparent hardness can also be measured on non-standard flat test pieces using methods N, H, L and M. The procedures described cannot provide for all possible shapes and dimensions of test piece, but cover some of the commonest types, such as O-rings.

This document specifies procedures for the calibration and verification of durometers of types A, D, AO and AM (see ISO 48-4), IRHD pocket meters (see ISO 48-5), IRHD dead-load instruments (see ISO 48-2) and dead-load instruments using the very low rubber hardness scale (see ISO 48-3).

This document specifies a method for determining the indentation hardness (Shore hardness) of vulcanized or thermoplastic rubber using durometers with the following scales: — the A scale for rubbers in the normal-hardness range; — the D scale for rubbers in the high-hardness range; — the AO scale for rubbers in the low-hardness range and for cellular rubbers; — the AM scale for thin rubber test pieces in the normal-hardness range.

This document specifies a dead-load method for the determination of the hardness of very soft vulcanized or thermoplastic rubbers using the very low rubber hardness (VLRH) scale. The relation between the depth of penetration and the VLRH scale is linear.

This document specifies a method for the determination of the apparent hardness of vulcanized- or thermoplastic-rubber roller covers, expressed as the Pusey and Jones indentation value. The Pusey and Jones plastometer apparatus is used to measure the depth of indentation of an indentor under a specified force into the surface of the rubber. The indentation value is not the same as that measured by the international rubber hardness test method ISO 48-2, since in this method the rubber immediately adjacent to the indentor is precompressed. The Pusey and Jones indentation value is an inverse measurement of hardness, i.e. the harder the rubber the lower the Pusey and Jones indentation value.

This document specifies a method for determining the indentation hardness of vulcanized or thermoplastic rubber by means of a pocket hardness meter calibrated in IRHD. The use of such meters is primarily intended for control, not specification, purposes (for specification, see ISO 48-2). It is possible to increase precision by fixing the pocket hardness meter on a support.

This document specifies a method for the determination of the apparent hardness of vulcanized- or thermoplastic-rubber roller covers, expressed in Shore hardness, for measurement where only medium precision is required. The method and apparatus used are essentially those described in ISO 48-4, the measurements in this case being made on the curved surface of the conditioned rubber-covered roller rather than on a flat test piece. Shore type A and type D instruments are specified, the latter being used for measurements on rollers of high hardness. NOTE With some rollers, there can be significant variation in the thickness of the rubber over the surface of the roller, which could affect the measured apparent hardness.

This document specifies a method for the determination of the apparent hardness, expressed in International Rubber Hardness Degrees (IRHD), of vulcanized- or thermoplastic-rubber roller covers. The method is similar in principle to the methods used for the determination of the hardness of rubber in ISO 48-2 in that it consists essentially of measuring the depth of penetration of a spherical indentor operating under a specified force. The apparatus used is similar to that described in ISO 48-2, having a base specifically designed for application to roller covers and similar curved surfaces. NOTE With some rollers, there can be significant variation in the thickness of the rubber over the surface of the roller, which could affect the measured apparent hardness.