Gummi

Ämnesområden: Gummi
Kommittébeteckning: SIS/TK 154 (Gummi och gummiprodukter)
Källa: ISO
Svarsdatum: den 19 jun 2018
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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.

Ämnesområden: Gummi
Kommittébeteckning: SIS/TK 154 (Gummi och gummiprodukter)
Källa: ISO
Svarsdatum: den 22 jun 2018
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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 should only be used for 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.

Ämnesområden: Gummi
Kommittébeteckning: SIS/TK 154 (Gummi och gummiprodukter)
Källa: ISO
Svarsdatum: den 25 jun 2018
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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 % (m/m). 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 can lower the bottom limit of detection.

Ämnesområden: Gummi
Kommittébeteckning: SIS/TK 154 (Gummi och gummiprodukter)
Källa: ISO
Svarsdatum: den 12 jul 2018
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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, it is necessary for all measurements to be undertaken at the test temperature.

Ämnesområden: Gummi
Kommittébeteckning: SIS/TK 154 (Gummi och gummiprodukter)
Källa: ISO
Svarsdatum: den 17 jul 2018
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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 fact might affect the result when carrying out TR tests on thermoplastic rubbers, and the results obtained from such tests should be analysed with caution.

Ämnesområden: Gummi
Kommittébeteckning: SIS/TK 154 (Gummi och gummiprodukter)
Källa: ISO
Svarsdatum: den 7 aug 2018
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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 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.

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.

Ämnesområden: Gummi
Kommittébeteckning: SIS/TK 154 (Gummi och gummiprodukter)
Källa: ISO
Svarsdatum: den 7 aug 2018
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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 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.