SURFACE POTENTIALS OF CORONA-CHARGED FERROELECTRIC P(VDF-TrFE) COPOLYMER SAMPLES

Surface potential measurements are presented as a function of time for negatively corona charged P(VDF-TrFE) samples in a constant current corona triode kept at low humidity levels. The surface potential curves roughly display three time regions, the middle one being a plateau at the coercive field where dipole switching occurs, preceded and followed by capacitive charging regions. This behavior is characteristic of ferroelectric polymers, as has already been reported for PVDF. The experimental results are interpreted by neglecting the conduction through the sample, assuming a dynamics for the electrical polarization which depends on the time only through the changing electric field, and also by assuming a distribution of coercive fields. This analysis allows the determination of a mean coercive field and remanent polarization of about 43 mC/m(2) and 56 MVlm, respectively.