Standardised test methods for rubber materials in low temperatures

For rubber materials there are four important standardised test methods for low temperatures:

TR test according to ISO 2921
Gehman test according to ISO 1432
Brittleness test according to ISO 812
Low temperature compression set according to ISO 815-2

Briefly, these methods are as follows:

1. TR test according to ISO 2921. This method determines the low temperature characteristics by thetemperature retraction procedure. The values TR₁₀ and TR₃₀ are often used in material specifications. The software can present a curve with the elastic retraction up to 70 %.

Read more: TR tester, ET 01

2. Gehman test according to ISO 1432. This method measures the relative stiffness as a function of the temperature. The result is presented as the relative stiffness where the stiffness in RT is 1. If the test piece dimension are put into the software it can also calculate the modulus as a function of temperature.

Read more: Gehman tester, ET 02-II

3. Brittleness test according to ISO 812. This method determines the lowest temperature at which rubber materials do not exhibit brittle failure when impacted under specified conditions.

4. Low temperature compression set according to ISO 815-2. This test measures the elastic recovery after a test piece has been held compressed at low temperature for some time.

Combinations

The TR tester, Gehman tester and Brittleness tester can be combined using the same base unit and a rig changing system.

The combined instrument consists of a base unit with a cooling bath and the electronics. The three different test rigs are then mounted on a carousel. No lifting is necessary when switching from one method to another.

An automatic computerised low temperature tester increases the precision up to 5 times. Also, the capacity increases by about 50 % and the labour time decreases by about 75 %.