Polymer piezoelectret films with ordered structure

Preparation of piezoelectret films with ordered void structure by using a template method is described. The structure of films consists of two layers of non-porous fluoroethypropylene (FEP) and one layer of non-porous polytetrafluorothylene (PTFE). The piezoelectricity of such fluorocarbon polymer films is investigated by measuring the quasi-static piezoelectric d₃₃ coefficients using positive piezoelectric effect. And the thermal stability of the films is studied by taking the measurement of d₃₃ decay at elevated temperatures. The results show that the quasi-static piezoelectric d₃₃ coefficients around 300 pC/N are achieved and its Young´s modulus is about 0.28 MPa. Compared with the fluorocarbon polymer films with disordered void structure, the films with ordered structure shows a much improved thermal stability of d₃₃. Pre-aging treatment can further improve the thermal stability of d₃₃.