Radiation induced oxidative degradation of polymers—I

Abstract

Abstract The γ-ray induced oxidation of polyethylene and ethylene-propylene copolymer films has been studied to obtain technological information on reducing the period in the radiation resistance testing of polymer materials. The polymers were irradiated under pressurized oxygen atmosphere (0.21∼10 atm) at high dose rate (0.5∼1 Mrad/h) in order to accelerate the oxidative degradation. The depth of oxidation region in the film was estimated by the gel fraction measurement. The depth was well agreed with the oxygen penetration region, which was calculated using the observed diffusion coefficient and solubility constant of oxygen in the film and specific rate of the oxygen consumption during irradiation. It was found that the depth of oxidation region was proportional to the square root of [oxygen pressure/does rate] and that the testing period could be reduced by higher dose rate irradiation at higher oxygen pressure.