An NMR, DSC, and IR spectroscopy study of the composite formed during low-temperature postradiation polymerization of C2F4 in the presence of a 3D graphene material

Abstract

By solid state magic angle spinning nuclear magnetic resonance spectroscopy (NMR), differen tial scanning calorimetry (DSC), and IR spectroscopy, polytetrafluoroethylene (PTFE) samples obtained by low temperature (T = -196°C) postradiation polymerization of tetrafluoroethylene (C 2 F 4 ) and C 2 F 4 mix tures with a 3D graphene material formed by the microwave exfoliation of graphite oxide films (MEGO) have been investigated. It has been shown that the melting point of PTFE in the PTFE-MEGO composite is 332.5°C, which is 8.8°C above the melting point of pure PTFE obtained under the same conditions. Accord ing to the measured values of specific enthalpy of melting ΔH m (51.5 and 45.4 J/g), the degrees crystallinity (x c ) of 0.63 and 0.55 have been calculated for the pure polymer and the composite, respectively. It has been also found that none of the PTFE containing samples examined has terminal CF 3 groups typical of PTFE prepared by conventional suspension polymerization.