Electrical properties of cyanoethylated polysaccharides.

Abstract

Dielectric and piezoelectric constants of pullulan, dextran and amylose which were cyanoethylated were measured as functions of temperature and draw ratio. The cyanoethylated polysaccharides having amorphous structure showed two relaxation processes; glass transition at around 120°C and side chain dispersion due to cyanothyl group at -90°C. The dielectric constant, which depended on the molecular orientation of films, was more than 20 for the highly oriented films. Small intrinsic piezoelectric effect, e14, was observed in the drawn film. This may be attributed to the strain of amorphous chain backbone. The sample poled near glass transition temperature revealed a piezoelectric effect e31 on the basis of a C-CN dipole orientation.