Temperature Dependence of ESR Spectra of Irradiated Polytetrafluoroethylene

Abstract

The double quintet spectrum in the ESR spectra of irradiated polytetrafluoroethylene, which is identified as the radical —CF₂ĊFCF₂—, varies its spectral shape with temperature. The changes in the linewidths of component lines in room‐temperature region are compared with the results of NMR and dynamic mechanical properties and are ascribed to the rotational motion of chains in crystalline regions. The change of isotropic splittings of the quintet from 61 G in rigid state to 32 G in motional state is due to the motional averaging of angular dependences of the β fluorines relative to p orbital of the radical carbon atom. With the triplet spectrum the variation of hyperfine structure with temperature is observed, which is also due to molecular motions.