Films of poly(vinylidene fluoride) have been polarized to a high level of piezoelectric activity by application of high electric fields which would normally cause breakdown in the polymer. The high field poling is accomplished by interposition between the two metal electrodes of a dielectric plate which severely limits the current passing through the polymer film during local discharges. Fields with strengths up to an estimated value of 11 MV/cm were applied to 25‐mgr;m‐thick biaxially oriented films at room temperature over a period of a few minutes to a few hours without incidence of major breakdowns. The piezoelectrice31(=e32) coefficient of the poled film increases steadily with the applied field, reaching a value of 32 mC/m2at the estimated field strength of 11 MV/cm. X‐ray and ir analyses of the films before and after poling show that the polarization is accompanied by transformation of the nonpolar agr; to the polar agr; phase, and further to the bgr; phase depending on the field strength. However, the agr; to bgr; conversion is only partially complete even at the highest field used, indicating that further polarization may be achieved with still higher field strengths.
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