Processing and Properties of PTFE-FEP-PTFE Ferroelectret Films

This paper describes the manufacture of porous polytetrafluoroethylene (PTFE) and flu-oroethylenepropylene (FEP) films by pressing PTFE-FEP-PTFE films between metallic meshes to produce a porous ferroelectret material. The influence of uniaxial pressing force and processing conditions (temperature and presence of a vacuum between the polymer films) on the as-formed ferroelectret film are assessed in terms on pore (void) height, distribution of pore height and film quality. The piezoelectric d(33) coefficient (charge per unit force) of polarised films is measured and related to pore height and film quality.