Chemical Structures Formed in Electron Beam Irradiated Poly(tetrafluoroethylene-co hexafluoropropylene) (FEP)

摘要

The perfluorinated copolymer poly(tetrafluoro-ethylene-co-hexafluoropropylene) (FEP) was electron beam irradiated under vacuum at various temperatures ranging from room temperature to a temperature above the melting temperature of FEP.Changes of the chemical structure were analyzed by ~(19)F solid-state NMR and IR spectroscopy.Trifluoromethyl end groups were generated as a result of main chain scission at all irradiation temperatures studied.In addition,trifluoromethyl side groups in various environments and double bond structures were formed.Quantitative analysis showed that long-chain branches were formed at irradiation temperatures above 200 deg C.Furthermore,the hexafluoropropylene (HFP) units in FEP were found to be less sensitive to radiation than the perfluoropropyl vinyl ether (PPVE) units in poly[tetrafluoroethylene-co-(perfluoropropyl vinyl ether)] (PFA).