Molecular motions in PVDF were investigated by dielectric measurement

dynamic mechanical measurement

TSC and piezoelectricity. In the temperature range of -150-120℃

four relaxations were observed and their mechanisms were explained.Our experimental results showed that there are 2 peaks above room temperature and are quite different from those reported in literatures but same as the results of Kakutani.The relation between dielectric polarization and piezoelectric polarization was compared. The results indicated thet d'31 increases linearly with e'3. The slop at high temperature is greater than that at low temperature. It indicates that the piezoelectricity may be originated from orientation of dipoles.