Dielectric relaxation and resonance spectra of ferroelectric polyamide 11

Abstract

Ferroelectric polyamide 11 films were prepared by melt-quenching, cold-drawing and electrical poling. Ferroelectricity was checked by dielectric-hysteresis measurements. Dielectric spectroscopy was applied for determining piezoelectric constants from thickness-extension resonances as well as for investigating conformational changes due to quenching, stretching and electrical poling. A remanent polarisation of up to 35 mC/m/sup 2/, a coercive field of 75 MV/m and a piezoelectric d/sub 33/ coefficient of 2.7 pC/N were obtained. In the ferroelectric film, the dielectric /spl alpha/ relaxation is suppressed whereas the /spl beta/ relaxation is enhanced.