A thermal study on phase transition of high-energy electron-irradiated P(VDF–TrFE) 80/20 mol% copolymers

Ferroelectric–paraelectric (F–P) phase transition behavior of P(VDF–TrFE) 80/20 mol% under high-energy electron irradiation is studied based on X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermally stimulated depolarization current (TSDC). Irradiation causes reduction of the polar domain size and expansion of non-polar crystalline size from all-trans to trans-gauche conformation in nanometer range, showing the coexistence of polar and non-polar phase. Both the Curie temperature Tc and melting temperature Tm decrease and exceptional endothermic peaks appear during the heating process in DSC thermograms, indicating the non-polar phase embedded in the crystalline region for the irradiated copolymers. The effect of non-polar phase is also observed in TSDC measurement, which shows prominent current change with irradiation dose in the low temperature range. It is believed that the coexistence of the non-polar and polar phases leads to the change of phase transition behavior in the irradiated P(VDF–TrFE) copolymers with a high VDF content.