ROOM TEMPERATURE POLING OF POLY(VINYLIDENE FLUORIDE) WITH DEPOSITED METAL ELECTRODES.

Abstract

High values of pyroelectric and piezoelectric activity in fully-electroded films of poly(vinylidene fluoride) were obtained by ″conventional″ (non-corona) poling at room temperature with sufficiently high fields. The avoidance of breakdown while obtaining high activity requires an understanding of the time dependence of both breakdown and activity. Time-to-breakdown as a function of field, and room-temperature pyroelectric activity (7-14 days after poling at 23. 5 degree C) as a function of poling time and field were obtained for 25- mu m biaxially stretched films with evaporated aluminum electrodes. The highest activities were obtained by poling at the highest fields and poling to breakdown. A pyroelectric activity of 36 mu CK** minus **1m** minus **2 was measured two week after poling with a nominal field of 550 MV m** minus **1 for a nominal poling time of 10 s (reduced by multiple breakdown). The highest activity obtained with no apparent breakdown (31 mu CK** minus **1m**31 **2) was measured a week after poling with a field of 400 MVm** minus **1 for 10 s.