Thermal testing

TR-test is the most common method in Sweden when it comes to cold testing. TR stands for "Temperature Retraction", in Swedish we call the method "elastic return after freezing". The test is carried out so that the test specimens are stretched, usually 50%, and then cooled down at -70°C for 10 min. Most rubber materials then become completely rigid. The locking of the test bodies is released and then the samples are heated 1°C per minute and the return is checked.

Brittle point is a method in which a hammer is used to strike test rods cooled in a cold bath. The brittle point is the temperature at which the samples just don't break on impact.

The test is carried out so that a test rod is mounted in series with a calibrated steel wire. When determining the torsional stiffness of the rubber sample, both rubber and steel wire are rotated 180°. The 180° twist is distributed between the steel wire and the rubber sample in relation to their torsional stiffness and the twist angle of the rubber sample is determined. The test is then carried out at different temperatures to enable calculation of the torsional stiffness.

If you wish to determine the modulus as a function of temperature, you can advantageously use modern DMA equipment for this. In DMA testing, the viscous and elastic modulus are measured together with the damping over a temperature range. The test is performed dynamically either in bending, stretching, compression or shear. This test can replace most other cold tests.