Properties of triglycine sulfate/poly(vinylidene fluoride-trifluoroethylene) 0-3 composites

Composites of triglycine sulfate (TGS) powder dispersed in a poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE), 70/30 mol%) copolymer matrix have been prepared using solvent casting followed by compression moulding. The composites have been characterized by means of scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Three groups of samples have been prepared: unpoled composites, composites with only the TGS phase poled and composites with both phases poled. The observed relative permittivity of these composites are consistent with the predictions of the Bruggeman model. When the TGS and copolymer phases are poled in the same direction, the piezoelectric activities of the two phases partially cancel each other while the pyroelectric activities reinforce. The pyroelectric coefficients exhibit good agreement with the effective-medium model. These composites have high pyroelectric figures of merit which increase as the volume fraction of TGS increases.