Piezoelectric and dielectric properties of heat treated and polarized VF2/VF3 copolymers

Unoriented, heat treated, compression molded 400–800μm thick sheets prepared from VF2/VF3 resins with mole ratios 65/35–80/20 were poled and their dielectric and piezoelectric properties 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 transition temperatures and latent heats increase at each stage of treatment. Heat aging the poled material below Tc causes ε and tan δ to increase and piezoactivity to decrease when measured at room temperature; however, initial values are recovered after several days room temperature storage.