Piezoelectric activity in a copolymer of acrylonitrile and methylacrylate

Results of investigations of piezoelectric properties in a copolymer of acrylonitrile and methylacrylate are summarized. A preliminary explanation is given of the observed phenomena on the basis of surface potential measurements. The maximum values of piezoelectric strain coefficient d₃₁ obtained after optimizing the poling conditions for stretched and unstretched films were around 3 and 0.85 pC/N, respectively. The time stability of piezoelectricity was found to be relatively low. A hysteresis loop of electric displacement versus electric field was observed and assumed to be a manifestation of a ferroelectriclike behavior. All the observations point to a dipolar nature of piezoelectricity where ferroelectric and frozen-in dipole orientations obviously superimpose