EFFECTS OF PLASTICIZER ON THE MECHANICAL AND FERROELECTRIC PROPERTIESOF UNIAXIALLY ORIENTED BETA-PHASE PVF2

The ferroelectric, piezoelectric, and dynamic mechanical properties of uniaxially oriented films of poly(vinylidene fluoride) PVF2, undoped and doped with a plasticizer, tricresyl phosphate (TCP), were investig ated. X-ray diffraction studies were carried out and show that for uni axially oriented films, as dopant concentration increased, the percent age of nonpolar alpha-phase increased. These results also confirmed pr evious studies that indicate that the dopant resides in the amorphous regions. The piezoelectric coefficients (d(31) and e(31)), pyroelectri c coefficient (p(y)), and remanent polarization (P-r) were observed to be enhanced by doping with TCP. Measurements of the pyroelectric coef ficient, p(y), showed that the dopant produced a large increase in p(y ) from 19.6 to 28.5 mu C/m(2)/K, suggesting an increase in the thermal expansion coefficient, alpha(3). The data also suggest that a small a mount of dopant in the noncrystalline regions greatly enhanced the hig h-temperature stability of the remanent polarization. (C) 1996 John Wi ley & Sons, Inc.