Electrical properties of novel three-phase polymer nanocomposites with a high dielectric constant

Abstract

Novel three-phase poly(vinylidene fluoride) (PVDF)/lead zirconate titanate (PZT)/expanded graphite (EG) nanocomposites were prepared using the solution method followed by hot pressing. The loading of PZT powder was varied from 0 to 85 wt% (∼57 vol%) in the PVDF matrix. Scanning electron microscopy revealed uniform dispersion of PZT particles in the matrix. X-ray diffraction showed the presence of α-phase of PVDF in the nanocomposites. Dielectric constant of the 80 wt% (C-80) composites increased to approximately 57 and it was further increased to approximately 192, 237 and 842 for the C-80 nanocomposites containing additional EG content of 0.25 wt%, 0.50 wt% and 0.75 wt%, respectively. However, it decreased with increasing frequency. The electrical conductivity and dissipation factor also increased significantly with increasing content of EG. Various theoretical models were used to rationalize the dielectric behaviour of binary composites.