Study of the mechanism of macroradical reactions in solid polymers: 2. Decay of alkyl macroradicals in linear polyethylene at low temperatures

Abstract

Kinetic data on the decay of alkyl macroradicals in polyethylene generated by γ-radiation at 77 K have been interpreted in three temperature regions within the diffusion-controlled reaction model at the activation-energy level. Various possible molecular mechanisms that could account for the approach of the reactive centres have been tested from the viewpoint of chemical and physical migration of radicals. Molecular mechanisms have been proposed for the second and third decay regions. They indicate the participation of segmental conformational motion of chain ends in the second region, and the connection of intermolecular hydrogen abstraction with the mobility of the free ends and inner parts of the chains in the third region in amorphous zones of polymers.