High performance polyvinylidene fluoride films prepared by solid-state coextrusion

High performance polyvinylidene fluoride films were successfully obtained by solid-state coextrusion of dry gel films to an extrusion draw ratio of 9. They exhibit square D-E hysteresis loops with remanent polarization 100 mC/m². The electromechanical coupling coefficient determined by thickness extensional mode piezoelectric resonance reaches 0.27. These values are 60% greater than those obtained for conventional uniaxially-drawn PVDF films. The electromechanical data taken over a broad temperature range are presented and the factors that achieve high performance are discussed.