The measurement of piezoelectric coefficient for PP cellular electret and the improvement of its piezoelectricity

In this paper, mechanical and dielectric parameters of virgin PP cellular film(t ype PQ50) were analyzed by dielectric resonance spectroscopy, and piezoelectric d33 coefficient of 18pC/N was measured. Up to 367pC/N of piezoelectric d33 coefficient for PP cellular electret was performed by means of pr essure-expansion techniques under the reasonable treatment conditions, which is about 20 times higher than that of famous ferroelectric polymer β-PVDF and whic h is higher than that of piezoelectric ceramic PZT. Based on scanning electron m icrograph and according to the piezoelectric theory model for PP cellular film t he structural and physical sources for high piezoelectric coefficient of these k inds of nonpolar porous film electret with space charge were discussed.