Mechanism of radiation‐induced degradation of poly(methyl methacrylate) as studied by ESR and electron spin echo methods

Abstract

Abstract The role of radical species in the degradation of poly(methyl methacrylate) (PMMA) induced by γ‐irradiation has been studied by means of electron spin resonance and electron spin echo spectroscopy. The major radical species generated initially at 77 K are assigned to main chain  CH  and side chain  COOCH 2 radicals, and  COOCH anion radical. Only the  COOCH 2 radical converts to the scission‐type  CH 2  C(CH 3 )COOCH 3 radical on warming the sample of >180 K. A part of the  CH  radical disappears on warming the sample of >265 K. It is concluded that the scission of PMMA main chain occurs by the intramolecular process from the  COOCH 2 radical as the precursor state.