Greffage de l'acrylonitrile sur le polyethylene et les copolymeres ethylene-propylene peroxydes par voie radiochimique

The radiation-induced peroxidation of polyethylene and ethylene-propylene copolymers was investigated under different irradiation conditions (temperature, dose and dose-rate). The buildup of peroxides was derived from the kinetics of the graft copolymerization of acrylonitrile on the irradiated polymers. The results show that the mechanism of peroxidation of polyethylene depends on irradiation temperature. A chain hydroperoxidation is observed at a certain temperature, largely above T_g of the polymer, whereas a single step peroxidation leading to a mixture of biperoxides and hydroperoxides occurs at lower temperatures. The critical temperature above which chain hydroperoxidation sets in increases the higher the dose-rate. For the poly(ethylene-co-propylene), special precautions were taken to remove the anti-oxidant of the polymer. A chain hydroperoxidation process was observed at all temperatures above T_g. These various results are discussed.