Detection of sharp DSC peak during the phase transition from the low-temperature phase to the cooled phase of vinylidene fluoride-trifluoroethylene copolymers

摘要

The structural changes occurring in the ferroelectric phase transition of vinylidene fluoride-trifluoroethylene (VDF-TrFE) copolymers were investigated to study the essential features of the transitional mechanism. The transition is associated with three types of crystalline phases: the low-temperature (LT) phase, the high-temperature (HT) phase, and the cooled (CL) phase. The transitional behavior depends largely on the type of samples used in the experiments. The copolymer with VDF content 70-80 mol% showed a clear and discontinuous first-order transition between the LT and HT phases at relatively high temperature close to the melting point.