Photoradiation cross-linking of polyethylene

Cross-linking of polyethylene (PE) under combined action of ionizing radiation (gamma-radiation with intensity about 500 rad/sec at 300 and 77 K) and UV light has been studied by EPR, infrared-spectroscopy, mass-spectrometry, and determination of gel-fraction. Efficiency of PE cross-linking at 300 K increases 5-fold upon simultaneous action of ionizing radiation and UV-light and 1.3-fold when the action is successive. At the same time a rise is observed in hydrogen yield and trans-vinylene unsaturation. Thus, upon successive action of γ-radiation and UV-light at 77 K, the content of gel-fraction increases about 2.5 times, hydrogen yield 14 times, and trans-vinylene double bonds about 23 times. The formation of these products during photolysis is related to photoradical chain reactions which lead to the reaction of C-H bond rupture between the adjacent polymer molecules, the rupture being photosensibilized by alkyl radicals