Properties of piezoelectric poly (vinylidene fluoride) films irradiated by γ-rays

Abstract

Abstract Recently, we reported1 the thermal aging data of uniaxially stretched and poled PVDF films and showed that the retention characteristic of piezoelectric coefficient can be improved significantly by irradiating the poled films with a moderate dose (ca. 40 Mrad) of γ-rays. Further studies have revealed a similar improvement of the dimensional stability in the irradiated films. In addition, stress relaxation tests under small tensile strains showed that the inverse stress relaxation, commonly observed in the uniaxially stretched polymers at elevated temperatures, has been suppressed markedly by the irradiation. However, the film showed a steady decrease in its tensile strength with increasing dose and became embrittled in the direction perpendicular to the initial draw direction as the γ-dose exceeded 50 Mrad.