Photoinitiated crosslinking of low density polyethylene. III: Degradation and stabilization of photocrosslinked polyethylene

Electron spectroscopy (ESCA) and reflectance infrared spectroscopy (ATR) were used to measure surface oxidation of photocrosslinked polyethylene. The deterioration of bulk properties during an artificial weathering test was also measured. It was found that the UV‐irradiation during crosslinking process decreases the stability of the material considerably. Three kinds of antioxidants and photostabilizers (hindered phenols, hindered amines, and organic sulfides) which have no absorption in the UV region of 300 to 400 nm were added before crosslinking to improve the stability of the crosslinked material. Neither the rate nor the degree of photocrosslinking at different depths of the sample were affected significantly by these additives. It was found possible to prevent the decrease in stability due to the photocrosslinking by using small amounts of a stabilizer, e.g. 0.05% Tinuvin 770 (hindered amine).