Thermal and structural properties of high-energy electron irradiated poly(vinylidene fluoride-trifluoroethylene) copolymer blends

Thermal and structural properties of high-energy electron irradiated ferroelectric blends by poly(vinylidene fluoride-trifluoroethylene) 56/44 and 80/20 mol% copolymers have been investigated by thermally stimulated depolarization current (TSDC), differential scanning calorimetry (DSC) and X-ray diffraction measurements. The temperature peaks observed in TSDC spectra of the blends decrease with the irradiation dose, associating phase transitional characters of the parent copolymers. And their distribution shows the existence of two types of crystallite, which become more clear after irradiation, demonstrating that the miscibility in the crystalline region for their large compositional discrepancy (24 mol% in their VF2 contents) in the blend. In DSC thermograms, it is found that the Curie temperature and melting temperature decrease with the dose. The ferroelectric-to-paraelectric (F-P) transition temperatures and enthalpies in the blends merge into one with the increasing of dose, which indicates a strong lattice coupling. X-ray diffraction shows some degree of mixing inside a crystal lattice due to significant changes in the F-P phase transition behavior from all-trans to trans-gauche conformation in nanometer range after irradiation.