Effect of microstructure on the macroscopic properties of a biphasic composite material

Consider a biphasic composite material consisting of completely unformed, spherical particles distributed (randomly) with the same spherical symmetry in an isotropic and incompressible carrier. To study the effect of microstructure on the macroscopic properties µp, µn and μa of the composite material, as determined by
the corresponding PCW type estimates. Determine the macro ratios of Poisson νp and νn of the material at the boundary as the rib fraction of the sphere tends to infinity.