LAUSR

For practical application, studying the mechanism governing the macroscopic dielectric properties of polymer composites at low concentration is of great significance. A three-dimensional (3D) representative model with randomly dispersed grains in polymer matrix has been established and calculation results of effective permittivity of BT/PVDF composites with finite element method (FEM) show good consistency with experimental measurements, which demonstrate that the distribution of electric field in ceramic particles/polymer composites at low concentration can be approximated by the electrostatic field. Furthermore, the relationship between the internal electric field and dielectric properties of composites has been established. The effect of grain size in submicron and its dielectric constant to the effective permittivity of composites are fully investigated. The former shows of negligible significance compared with the evident effect of volume fraction, while the latter presents saturation as increasing the permittivity ratio between ceramic particle and polymer.