Piezoelectric and Dielectric Properties of Heat Treated and Polarized VF2/VF3 Copolymers

Unoriented, heat treated, compression molded 300-800 ¿m thick sheets prepared from VF2/VF3 resins with ratios 65/35-80/20 were poled and their dielectric and piezoelectric properites studied. Both the permittivities and losses were reduced upon heat treatment before poling and further reduced after poling. Resulting piezoactivity is higher on heat treated material. The Curie (ferroelectric-paraelectric) peak transition temperatures (¿Tc) increase at each stage of treatment. With short-term heating of the poled material below ¿Tc, ¿ and tan¿ increase and the piezoactivity decreases when measured at room temperature; however, initial values experience recovery (incomplete) after several days room temperature storage.