Effect of interphase on effective permittivity of composites

A unique model for predicting the effective permittivity of a filler/polymer composite system with an interphase is presented. In order to take into account the interactions between the filler and the matrix as well as filler-filler overlapping, a microscopic modification is introduced into the interphase volume fraction as a function of filler concentration. The proposed model shows that the effective permittivity relies on the volume fractions of the filler phase, the matrix phase and the interphase region as well as the permittivity of each phase. This model also provides a means to determine the volume and permittivity of the interphase in a composite by fitting the experimental data. Based on the present model, the effects of filler concentration, filler size, volume and permittivity of the interphase region on the effective permittivity of the composite are investigated. The theoretical results of the proposed model on filler/polymer composites are in agreement with experimental data.