Abstract: The effects of nano zinc oxide on the degradation of Irgafos 168 in nano zinc oxide-polypropylene (PP) films under sunlight exposure, ultraviolet (UV) irradiation and microwave irradiation were studied by using gas chromatography-mass spectrometry (GC-MS). The results indicated that the degradation rate of Irgafos 168 in nano zinc oxide-polypropylene composite films was increased gradually during sunlight exposure and UV irradiation until reaching equilibrium. The presence of nano zinc oxide in PP films began to accelerate the degradation of Irgafos 168 after 12 days of sunlight exposure. Furthermore, addition of the coupling agent also affected it. Compared to sunlight exposure, UV irradiation resulted in higher degradation of Irgafos 168 and the content of 2,4-di-tert-butylphenol, one of the degradation products, was increased to a maximum value at 24 h and decreased afterwards. Nano zinc oxide in PP films began to hinder the degradation of Irgafos 168 after 13 h of UV irradiation, and addition of the coupling agent only affected the generation of tris (2,4-di-tert-butylphenyl) phosphate, another degradation product, but had little impact on the degradation of Irgafos 168. Higher microwave power could accelerate the degradation of Irgafos 168, which was not significantly related with the number of microwave irradiation cycles, nano zinc oxide or the coupling agent.

Key words: polypropylene (PP), nano zinc oxide, Irgafos 168, degradation products