Evaluation of dielectric behaviour of particulate composites consisting of polymeric matrix and conductive filler

Abstract

Extension of the logarithmic law of mixtures enables equations to be formulated which describe the dielectric behaviour of particulate polymeric composites containing conductive particles. These equations give the permittivity and dielectric loss of the composite as a function of the permittivity of the polymeric matrix, the volume fraction and aspect ratio of the inclusions, and the frequency of the applied field. The proposed equations were tested with experimental data obtained over a wide range of frequencies and temperatures from composites consisting of epoxy resin and aluminium powder. Satisfactory agreement was observed when the volume fraction of the inclusions was small, but at higher values discrepancies appeared which are attributed to the intrinsic weakness of the logarithmic law of mixtures, on which the proposed equations are based.MST/3167