MICROWAVE FREQUENCY DIELECTRIC-PROPERTIES OF POLY(VINYLIDENE FLUORIDE) FILMS

The frequency dependence of dielectric constant epsilon', dielectric loss epsilon'', and dielectric anisotropy were determined for poly(vinylidene fluoride) (PVDF) in microwave frequencies from 4 to 13 GHz. The epsilon' and epsilon'' for PVDF films decreased with increasing frequency. Both epsilon' and epsilon'' were larger in the transverse direction than in the machine direction or draw direction, but the values at 12 GHz were smaller than those observed at 4.0 GHz. The angular dependence of epsilon'' at microwave frequency reflects the orientational distribution of molecules in the amorphous region. The orientation function was determined to be about 0.04 and 0.01 for uniaxially and biaxially stretched PVDF, respectively. (C) 1995 John Wiley & Sons, Inc.