Pyroelectricity and charge transport in a copolymer of vinylidene fluoride and tetrafluoroethylene

Previous investigations have shown that a copolymer of vinylidene fluoride and tetrafluoroethylene can be made piezoelectric and pyroelectric by the temporary application of an electric field.
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For applied fields in excess of about 250 kV/cm, the electrical response became independent of applied field, independent of poling temperature between 0° and 60°C, and independent of poling time between 5 minutes and 7 hours.
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Such behavior implied saturation of polarization, and values of polarization required to account for the piezoelectric response were well within the maximum to be expected from alignment of dipoles within the crystalline phase of the copolymer. Measurements on similar films now indicate that the polarization distribution within the films is non-uniform and varies with poling temperature. This paper presents these results and will propose a model of charge transfer within the film to reconcile the evidence for saturation polarization and nonuniform charge distribution.