A microstructural approach to the effective transport properties of multiphase composites

A group of physical properties, such as electrical conductivity, dielectric constant, magnetic permeability thermal conductivity and diffusion coefficient, are governed by the same form of constitutive equations and are therefore mathematically analogous. This group of physical properties of composite materials, usually referred to as the effective transport properties in the literature, is highly dependent upon the statistical arrangement of their constituent phases. Consequently, a successful theoretical solution to the correlation between the effective transport property and the microstructure has to address the statistics of microstructural feature. In this paper a new microstructural approach has been developed for predicting the effective transport properties of multiphase composites. In contrast with the existing models, the present approach can consider not only the effect of volume fraction but also the effects of particle shape and phase distribution. It has been applied to various two-phase and multiphase composites including porous materials. The theoretical predictions are in good agreement with the experimental data drawn from the literature. It has been shown that the present approach is superior to the various bounds in terms of the accuracy of prediction and the range of applicability. Finally, the effect of phase contiguity on the effective transport properties of two-phase composites has also been discussed. It is found that the effective transport properties increase with increasing phase contiguity in a given composite system.