Irradiation effects on synthetic polymers (EPR, EPDM) in salt solutions. IV. Stability evaluation by oxygen uptake

Ethylene-propylene samples (EPR and EPDM) were irradiated in NaCl solutions. They achieved a high stability at about 150 kGy. Oxygen uptake measurements pointed out that chemical stability against oxidation is changed with dose and salt concentration. Simultaneous processes (crosslinking and oxidative degradation) are considered. Time dependence curves of absorbed oxygen emphasize that alkyl radicals could react with oxygen and crosslinked bulk would be degraded afterwards. The most significant effect of radiation on tested elastomer samples was, obtained for 0.1%NaCl concentration. During these experiments additional effect of radiolysis products is overlapped on radiation action. Some mechanistic aspects of polymer radiation processing are discussed relative to various applications as dielectric materials.