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

摘要

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_2F_4) and C_2F_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.