Compression Relaxation

ASTM D575 & ASTM D6147


These test methods are useful in comparing stiffness of rubber materials in compression. They can be used by rubber technologists to aid in development of materials for compressive applications.

Test Details

These test methods cover two test procedures for determining the compression-deflection characteristics of rubber compounds other than those usually classified as hard rubber and sponge rubber.


This test method assesses the force decay upon rubber in various conditions, both physical and chemical. Also known as compression set relaxation, this standard covers two differing methods for determining the decrease in counterforce exerted by a test specimen of thermoplastic elastomer or vulcanized rubber which has been compressed under controlled conditions at a constant deformation. This method covers testing in both air and liquids.

Test Details

When rubber undergoes a constant strain, the force needed to maintain that strain decreases over time. Either physical or chemical processes may be responsible for this force decay; at low temperatures and/or short times, force decay is dominated by physical processes whereas at high temperatures and/or long times, chemical processes dominate. It is not safe to extrapolate force decay curves in order to predict ongoing trends in stress relaxation, nor use tests at high temperatures in lieu of accelerated tests for force decay at lower temperatures.

Types of materials…

typically tested in our laboratory under this method are:

  • Seals
  • Gaskets

Common Uses

This test is commonly used to determine service life for seals and gaskets.

There's more!

If you are interested in a test method that is not shown, please contact us and we will do our best to accommodate your testing needs. 


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