Abstract: Outdoor and indoor accelerated aging (thermal-oxidation and ultraviolet aging) of polypropylene (PP) and polypropylene/ethylene-propylene-diene monomer (PP/EPDM) blends were studied to monitor the change in mechanical properties and surface microstructure. The outdoor aging was carried out in three western regions of China: Yuli Xingjiang, Lasa Tibet, and Chengdu Sichuan. During the outdoor aging, the tensile strength of increased at the initial stage and decreased in middle and late stages due to degradation. The addition of EPDM greatly enhanced the anti-aging properties of PP, and the retention of tensile strength was up to 115% after 24 months aging in Chengdu. The tensile strengths of both PP and PP/EPDM were little affected during thermal-oxidation aging, but gradually decreased during UV aging. The accelerated indoor and outdoor aging could be correlated by a time equivalence considering both thermal-oxidation and UV.

Key words: polypropylene, ethylene propylene diene monomer, nature aging, thermal-oxidation aging, ultraviolet aging