The Decay of Irradiation Defects in Polymethyl Methacrylate

Abstract

The decay of defects in polymethyl methacrylate caused by γ-irradiation has been followed by electron-spin resonance. The samples were irradiated at room temperature and annealed at 80, 90, and 100 �C. Two radical species can be recognized by their different modes of decay. Some attempt is made to identify the chemical groups involved and to explain the decay mechanism.

Application of radical cage reactions in studies of microstructures of polymers and composites

“…Numerous studies established a characteristic feature of this reaction in solid polymers, viz., its kinetic arrest at constant temperature or its `stepwise' character. 6,8 The nature of this phenomenon was rationalised from different stands taking into account the structural-physical heterogeneity of the matrix, 9,10 differences in the interradical distances, 11 increased concentration of radicals in structural defects, 12 etc. However, the kinetic regularities observed in this process can be regarded only as an indirect indication to the dependence of the reactivity-based distribution of radicals on the structural-physical properties of polymers.…”

“…Analysis of KIE in the reaction of BCHC decay in PMMA 66,67 was performed using relations (11), (12) and the condition T& hMO 2 /mo C7H k, under which the linear temperature dependence is transformed into a T 72 dependence. The derived values of characteristic frequencies of intermolecular vibrations (O & 53 cm 71 & 10 13 s 71 ) correlate with the Debye frequencies for molecular crystals.…”