The Preparation And Properties Of PVDF/Ferroelectrics Ceramic Composites

On the basis of consulting of relative reference, the study evolution and present application of polymer/ceramic composites are detailedly introduced in this paper. It is inferred that the dielectric and piezoelectric properties of composites can be enhanced by the improvement of the interfacial interaction of polyner and ceramic.In this paper, 0-3 composites of the polyvinylidene fluoride (PVDF) and lead titanate(PT) were prepared by three different preparation methods. The relative dielectric constant e and the dielectric loss tangent tan 8 of the composites were measured at 30 ℃ using a LF Impedance Analyzer(HEWLETT PACKARD 4192). The piezoelectric coefficient d33 of composites were measured using a quasistatic d33 Analyzer (Z-3A). The interfacial interaction of composites was measured usinga SEM.Firstly, PbTiO3(PT) was prepared by sol-gel then PT was imbedded into PVDF matrix by melt-pressed. The structure and properties of composites are studied. The results show that PT prepared by sol-gel is amorphous and become crystal after sintered at 600℃, the disorder distribution of PT powders, the existing of a lot of hollow and the interfacial defect lead low dielectric properties of composites. To enhance dielectric and piezoelectric properties of composites the interfacial interaction of PVDF and PT must be improved firstly.Secondly a series of PVDF/PT composites were prepared by sol-gel. The structure and properties of composites are studied. The result shows that the sizes of PbTiO3 particles are nanometer, and PbTiO3 particles were wrapped by the polymer matrix, the interaction of two phases is strong, the dielectric properties of composites prepared by sol-gel are higher than these of composites prepared by melt-press attribute to the improvement of interaction of PVDF and PT. However the amorphous PT in composites lead the composites have nopiezoelectric properties.Lastly, a series of PVDF/PT composites are prepared by a new method, that was PT which have good dielectric and piezoelectric properties and PVDF/PT composites prepared by sol-gel were compounded by melt-pressed. The structure and properties of composites are studied. The results show that the sizes of PbTiO3 particles which is prepared by sol-gel are nanometer, PbTiO3 particles were wrapped by the polymer matrix, and adhered on the surface of PT, the interaction of two phases is strong, the relative dielectric constant e have a maximum value 36.4 and The dielectric loss tangent tan 8 is 0.08 at 40% volume fraction of PVDF. The piezoelectric coefficient d33 is 10 at 20% volume fraction of general PT.