Bending electrostriction and space-charge distribution in polyurethane films

Abstract

Application of an electric field bent a polyurethane single-layer film. The bending direction depended on the chemical structure of the polyurethane. A film made from a polyurethane (N-PU) that had phenylimino groups in its structure bent toward the anode side. On the other hand, another film made from a different kind of polyurethane (Nt-PU) that had nitrophenyl groups bent toward the cathode side. Measurements of the space-charge distributions in the films using a pulsed electroacoustic method revealed contrasting distributions between the films. That is, in the N-PU film, positive space charge accumulated near the cathode. In the Nt-PU film, the negative one accumulated near the anode. These contrasting results between N-PU and Nt-PU both in the bending direction and the space-charge distribution suggested a direct relation of space charge to the bending mechanism.