SELECTIVE LOCALIZATION OF PRIMARY RADIATION-CHEMICAL EVENTS IN SOLID ALIPHATIC-HYDROCARBONS AND RELATED POLYMERS AS EVIDENCED BY ESR

The selectivity of formation of primary radicals in irradiated solid h ydrocarbons and related polymers is analyzed on the basis of ESR studi es at low and super-low temperatures. The first direct experimental ev idence for selective localization of the primary alkyl radicals at con formational defects (gauche conformers) was obtained for high-density oriented polyethylene irradiated at 15 K. This result implies highly s elective primary C-H bond rupture, which correlates with the structure of the ionized molecules of linear alkanes. The correlation between t he spin density distribution in the primary hydrocarbon radical cation s and the initial mode of radical formation in the corresponding polym ers is discussed. Copyright (C) 1996 Elsevier Science Ltd