Improved piezoelectricity in solvent-cast PVC films

The piezoelectric coefficient of solvent cast polyvinyl chloride (PVC) films processed under simultaneous stretching and corona poling (SSCP) conditions has been enhanced by ~4× (d₃₁≈5.3±0.35 pC/N) as compared to the maximum value (0.5 to 1.3 pC/N) reported in the literature. The optimized values of d₃₁ are compared for SSCP, stretched and corona poled (STCP), and unstretched and poled films. An efficient dipolar orientation can be achieved by the SSCP method, leading to the highest piezoelectric coefficient. It was shown that d₃₁ decayed to ~70% of its original value after 14 months for both SSCP and STCP films. X-ray experiments reveal that the (110) and (210) reflections are considerably reduced in SSCP films as compared to STCP films. The orientation of (200) planes parallel to the film surface is preferred in the SSCP films. The crystallinity was found to increase with stretching in SSCP films. Young´s modulus for the unstretched, STCP and SSCP films was measured