Calculation of the Effective Diffusion Coefficient for Heterogeneous Media

1 Introduction In this paper we discuss the range of the applicability of our recent approach [1] for the effective diffusion coefficient (mobility) in two-phase systems, e.g. composite materials, porous media, polymer blends, matrices with inclusions. We derived the equation for D eff as a function of the partial diffusion coefficients of a defect (or probe particle) in inclusions, D 1 , with the fractional concentration Φ=0...1, and the diffusion coefficient in the host matrix, D 2 , taking into account the energy barrier for the particle penetration into an inclusion. We compare our results with previous theories, starting with the generally–accepted Maxwell-Garnett formula [2] and finishing with very recent studies [3].