80 / 2021-06-04 17:33:44

STUDY ON THE EFFECT OF PARTICLE SURFACE MORPHOLOGY ON THE DIELECTRIC PROPERTIES OF POLYMER COMPOSITES

It has become an urgent need to significantly reduce the volume and weight of capacitors by increasing the energy storage density of the essential polymer film materials, especially for those applications with limited space, such as shipborne ejection system, inverter valve in flexible power transmission system et al. By incorporating ceramic inorganic particles with the polymer matrix and changing the corresponding physical and spatial distribution properties, the dielectric properties of the composite material can be adjusted conveniently. In this paper, the influence of the particle surface morphology and the magnitude of roughness has been systematically studied with the help of numerical simulation. Both the permittivity and breakdown strength of the composites has been predicted by finite element method (FEM) and phase field method (PFM) respectively.

A representative simulation model with randomly distributed ceramic spherical particles in the organic matrix has been established by co-simulation of Matlab and COMSOL Multiphyscis software. A variety of particle surface morphologies, including spheroids, sinusoidal, triangular and random Gaussian distributions have been designed, and the corresponding magnitude of roughness were also changed. As a result, both the permittivity and the breakdown strength of the composites were significantly affected by the surface roughness of the particles. In the vicinity of the bulge with a small radius of curvature, the destructive electrical stress concentration occurs, reducing the breakdown strength of the composites. Furthermore, the surface morphology also strongly determined the interaction degree between adjacent particles, especially in high concentration, which in turn changes the dielectric properties of the composite material.