The degradation process leading to the compression set was oxidative crosslinking in nature. Additionally, the solvent swell tests showed a correlation between the compression set and crosslink density (CLD). Chang7 investigated the effect of changing Mooney viscosity on the hardness, elongation at break, and compression set of a sulfur-cured NBR rubber and reported reduction in the compression set as the Mooney viscosity was increased. Evidently, the compression set of NBR was influenced by many factors.