Complex Permittivity Models of Composite Dielectrics

This paper deals with analytical simulations of behaviour of loss frequency-dependent composite dielectric. Several equations of dielectric mixture theory were verified and the results were compared with measured values of these materials, which were prepared in good accord with the theoretical model. The studied dielectric spectroscopy frequency range was from 100 Hz to 1 MHz and we present one stochastic and one properly defined particular composite material composed of constituents with significantly different properties and volume factors. A definition of a suitable dielectric mixture and a volume factor of each component specification is necessary for qualified results evaluation of dielectric properties simulations. The materials used as insulation and/or an insulation part were chosen for the described experiment. First, epoxy resin was used as a host phase (matrix). The choice of sort of the inclusion (filler) phase is the problem of highest importance as far as analytical simulations are concerned. The results of the final composite properties are largely dependent on the inclusions properties, matrix and inclusion permittivity differences, inclusion distribution in the matrix, volume factor and especially the size and shape of the inclusion.