Tensile Set

Tensile set (also referred to as Permanent Set) is the extension remaining after a specimen has been stretched and allowed to retract in a specified manner, expressed as a percentage of the original length.

Tensile set is important to many commercial rubber products that expand and contract in normal service. For example, seals and gaskets are usually stretched and must return to their original size in order to function properly in the specific application. This ability is expressed in tensile set.

Testing of rubber materials and products for tensile set involves applying force to the material to determine the residual deformation of the sample.  After force has been applied, the deformation is partially permanent and partially recoverable.  For this reason, the periods of extension and recovery must be controlled to obtain comparable results.

Depending on the material or product to be tested, standard or custom test protocols can be used to provide meaningful data for performance evaluation.  One of the most common standardized protocols is listed below for reference.

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Common Test Protocols


Standard Test Methods  for Vulcanized Rubber and Thermoplastic Elastomers – Tension