Dynamic Mechanical Dispersion in Copolymers of Vinylidene Fluoride and Trifluoroethylene

Abstract

Copolymers of vinylidene fluoride (VDF) and trifluoroethylene (TrFE) with TrFE content ranging from 48 to 100 mol% were studied by dynamic mechanical measurements in a temperature range of 173 to 373 K at 3.5 Hz. The α and β dispersions were observed around 313 and 250 K in decreasing order of temperature and the Tt dispersion occurred at higher temperature above the α dispersion for copolymers with 48 to 71 mol% TrFE. It was inferred for copolymers with 48 to 71 mol% TrFE from the dependence of these dispersions on degree of crystallinity that the α and β dispersions were due to micro-Brownian molecular motions of TrFE rich and VDF rich sequences respectively in amorphous regions and that the Tt dispersion was connected to the phase transition in crystalline regions. It was noted that the β dispersion in copolymer with higher TrFE content was related to the local molecular motions in amorphous and crystalline regions.