Ferroelectric hysteresis effects in poly(vinylidene fluoride) films

Abstract

Investigations of the piezoelectric response of biaxially oriented poly(vinylidene fluoride) films subjected to a series of static positive and negative poling fields produces a hysteresis curve for d₃₁ and e₃₁ showing the ferroelectric character of phase IV. Examination of changes in the crystalline regions, using differential scanning calorimetry and x‐ray methods, of films cycled (statically) through large positive and negative poling fields provides insight into the switching mechanisms of both phase I and phase IV. The experimental results show a cyclic broadening and narrowing of the endothermic melting peaks as the film polarization is switched. Cyclic changes in the intensities of the phase I (110) (200) and phase II (or phase IV) (100), (020), and (110) reflections are also observed.