Increase in crystallinity in poly(vinylidene fluoride) by electron beam radiation

Abstract

Abstract We examine the influence of high‐energy radiation and subsequent aging and orientation on the degree of crystallinity of poly(vinylidene fluoride) (PVDF) films. In particular, PVDF films were exposed to electron beam radiation (doses up to 50 Mrad) and aged at room temperature for varying lengths of time followed by uniaxial orientation. The degree of crystallinity of these films was found to increase significantly with increasing radiation dose. In addition, a further substantial increase in the degree of crystallinity was observed upon subsequent aging of irradiated films at room temperature. Upon orientation, in addition to a further rise in the degree of crystallinity, the crystallites were observed to undergo the α form → β form transformation, the latter phase being the polar phase effective for piezo‐electric/pyroelectric activity.