Preparation and piezoelectricity of fluorocarbon polymer piezoelectret films with ordered void structure

Abstract

A hard template process for preparing piezoelectret films with ordered void structure was described. By using the fabrication process, fluorocarbon polymer piezoelectret film was prepared. The scanning electron microscope (SEM) images showed that the fluorocarbon polymer film piezoelectret has very regular void structure as expected. The piezoelectricity of the fluorocarbon polymer film was investigated by measuring the quasi-static piezoelectric d33 coefficient using positive piezoelectric effect. The thermal stability of d33 was studied by taking the measurement of d33 decay at elevated isothermal temperatures. The results showed that a piezoelectric d33 coefficient of 300 pC/N was achieved. Compared with the fluorocarbon polymer film with disordered void structure, the film with ordered void structure has much improved thermal stability of d33, which can be further improved by pre-ageing treatment. The piezoelectric d33 coefficient is dependent on the applied pressure considerably in the range of 2—35 kPa, which is probably associated with the enhancement of Young’s modulus of the film with the increasing pressure.