Degradation evaluation of ethylene-propylene-diene monomer (EPDM) rubber in artificial weathering environment by principal component analysis

Artificial weathering tests on ethylene-propylene-diene monomer (EPDM) containing 5-ethylidene-2-norbornene (ENB) as diene were conducted in a xenon lamp light exposure and weathering equipment for different time periods. Principal component analysis (PCA) was used to evaluate the 12 degradation parameters of EPDM including surface properties, crosslink density and mechanical properties. The results showed that the combined evaluating parameter Z of EPDM degradation increased quickly in the first 12 days of exposure and then leveled off. After 45 days, it began to increase rapidly again. Among the 12 degradation parameters, the crosslink density is strongly associated with tensile stress at 300% elongation and tear strength. The surface tension is also well correlated with the color aberration.