Abstract
Electron spin resonance (ESR) spectra at X band for the midchain peroxy radical (-CF/sub 2/CF(OO.)-CF/sub 2/-) in ..gamma..-irradiated poly(tetrafluoroethylene) (PTFE) are studied in the temperature range 300-500 K. The midchain fluoroalkyl radical (-CF/sub 2/CFCF/sub 2/-) is formed by decomposition of peroxy radicals and splittings from ..cap alpha..-, ..beta.., and ..gamma..-fluorine nuclei are respectively 88.0, 31.5, and 3.0 G at 493 K. Line widths from the midchain peroxy radicals increase with increasing temperature and are analyzed in terms of a motional process with an activation energy of 16.1 kJ/mol. The suggested motional model is a helical twisting of the polymer axis as has been observed in the end-chain peroxy radical in poly(tetrafluoroethylene) and in poly(vinylidene fluoride).
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