When a polymer is used together with others,its aging process will be affected by the adjacent polymers.This infectious behavior between polymers makes the aging process more complex than that of an individual material.In this study,infectious behavior in photooxidation of polymers was investigated.Polypropylenes (PPs),an unstabilized PP and a commercial PP,were chosen as the infection sources.Six typical polymers,high density polyethylene (HDPE),low density polyethylene (LDPE),polystyrene (PS),polycarbonate (PC),poly(ethylene terephthalate) (PET),and polyamide 6 (PA6),were used as the targets.The degree of oxidation of the targets was evaluated by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR).An accelerating effect of two infection sources on the photo-oxidation of the target polymers was observed.Potential infectious agents from the infection sources were detected by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and gas chromatography (GC).The acceleration effect of two main infectious agents,i.e.acetone and acetic acid,on the photo-oxidation of the commercial PP was verified.The infectious effect of the infection source on the target polymer was considered to be a comprehensive result of the effects of a variety of infectious agents.