Analysis and development of a ferroelectret cellular PP film

In this study, we developed a new type of ferroelectret cellular film by using commercial polypropylene film (PQ60). We first use gas diffusion expansion method to create the void structure inside PQ60 followed by using corona discharge to trap charges in the voids. Then dynamic method was chosen to measure the piezoelectric constant d33. The measured d33 value was above 150 pC/N. We further use Laser-Intensity-Modulation Method to measure the heat induced current from the surface of the cellular PQ60 film at various intensity-modulated frequencies. The result of LIMM can be used to analyze sensor and actuator performance in ferroelectret.