Study on chemical structures of poly (tetrafluoroethylene-co-perfluoroalkylvinylether) by soft-EB irradiation in solid and molten state
Poly (tetrafluoroethylene-co-perfluoroalkylvinylether) (PFA) was irradiated by soft electron beam (soft-EB) under nitrogen gas atmosphere in solid-state and its molten state, respectively. The changes of thermal property and chemical structures of irradiated PFA in solid-state and molten state were studied by differential scanning calorimetric analysis (DSC) and solid-state 19F magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. By DSC analysis, the melting temperature shifted to lower temperatures, and crystallinity decreased with increasing soft-EB dose. By solid-state 19F MAS NMR spectroscopy, the new signals was observed and the detected new signals in irradiated PFA at 315 °C and at 30 °C were due to the tertiary carbon group with branching site (Y-type crosslinking site), perfluoro-propylene site and chain end methylene groups, respectively. Moreover, the molar ratio of perfluoroalkylvinylether (FAVE) structure to -CF 2- units decreased with increasing dose.