Piezoelectricity of a vinylidene fluoride-trifluoroethylene copolymer

A vinylidene fluoride-trifluoroethylene copolymer was studied to determine its piezoelectricity. The Curie temperature at 65 °C made it easy to polarize this material. The piezoelectric constant was proportional to the polarization. The piezoelectric constant was 22×10−12 C/N for a sufficiently polarized copolymer film with 51 mole % of VDF. The copolymer with 55 mole % of VDF had the largest piezoelectric constant under an appropriate poling condition. The piezoelectricity of the VDF-TrFE copolymer was discussed by a phenomenological theory based on dipole orientation.