Radiolytic Stress Relaxation of an Ethylene Propylene Copolymer

Abstract The kinetics of network chain scission induced by γ-rays has been studied by stress relaxation at constant elongation under vacuum and in air. The rate of chain scission of a 1:1 ethylene propylene copolymer was found to be independent of initial network chain density, and the initial rates were roughly the same in air and under vacuum. Parameters for crosslinking induced by γ-rays were obtained by sol extraction and by measurement of elastic properties of the resulting networks. Values of G for scission and crosslinking and gel dose, obtained by stress relaxation, by elastic properties, and by sol extraction, were found to agree with each other.