Rubber

Heat, oxygen, ozone, ultraviolet radiation, chemicals, repeated deformation, and prolonged service can degrade rubber and change its properties over time. Depending on the material and exposure, rubber may become harder, more brittle, cracked, swollen, softened, or less able to recover after deformation. Specifications, reference samples, service conditions, and material-test results can be compared to identify degradation mechanisms consistent with the observed changes. ASTM D573 provides an accelerated air-oven method for evaluating changes in vulcanized rubber caused by elevated-temperature aging.

Compression set can matter because seals, gaskets, isolators, and other rubber components often depend on their ability to recover after prolonged compression. Excessive permanent deformation can reduce sealing force or affect dimensional performance. Compression-set results may be evaluated alongside component geometry, temperature exposure, material formulation, and time under load to determine whether permanent deformation contributed to the reported problem.

Testing can help distinguish a material problem from service-related damage by comparing the rubber's measured properties and physical condition with its manufacturing and service history. Relevant evidence may include tensile properties, hardness, microscopy, chemical or thermal characterization, dimensions, age, loading, temperature, and chemical exposure. ASTM D412 also recognizes that tensile properties depend on test conditions such as temperature, extension rate, specimen geometry, and conditioning, so controlled comparisons are important.