EPR spectrum of irradiated oriented polytetrafluoroethylene

Abstract

The electron paramagnetic resonance (EPR) spectra of free radicals trapped in oriented samples of polytetrafluoroethylene, after high-energy irradiation in vacuum, are dependent on the angle between the orientation direction and the direction of the magnetic field applied in the EPR experiment. This orientation dependence is considered in the light of recently published data on fluorine-containing free radicals trapped in irradiated single crystals of fluorocarbon compounds. The radical -CF2-CF-CF2- put forward to account for the EPR spectra of randomly oriented samples of irradiated polytetrafluoroethylene provides a satisfactory explanation of the principal features of the spectra and their orientation dependence. Several additional weak hyperfine lines have been observed and possible origins of these are discussed.