Electron Spin Resonance of γ-Irradiated Tetrafluoroethylene—Hexafluoropropylene Copolymers

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Abstract
Radicals produced in tetrafluoroethylene—hexafluoropropylene copolymers γ‐irradiated at room temperature in vacuo have been studied by electron spin resonance. Besides the well‐known spectra assigned to the radicals ···CF2–ĊF–CF2··· and ···CF2–CF2–O·, a poorly resolved eight‐line spectrum was found and tentatively assigned to the tertiary carbon radical ···CF2–Ċ(CF3)–CF2···. Upon heating, this radical disappeared much faster than the others. This is probably because it is trapped in a region where the regular crystallization of the copolymer chains was perturbed by trifluoromethyl groups. The temperature and orientation dependence of the spectra were also examined and interpreted in terms of the proposed radical.