Reciprocal Relations , Bounds and Size E ects for Composites with Highly Conducting Interface

We provide a reciprocal relation linking the e ective conductivity of a composite with highly conducting phase interfaces to that of a composite with the same phase geometry but with an electrical contact resistance at phase interfaces. A eld relationship linking the electric eld inside a composite with highly conducting phase interfaces to the current in a composite with contact resistance between phases is found. New size e ects exhibited by isotropic particulate suspensions with highly conducting interface are obtained. The e ective properties of periodic composites are shown to be monotonically increasing as the size of the period cell tends to zero. The role of surface energy for energy minimizing polydisperse suspensions of disks is examined; a necessary condition for isotropic polydisperse suspensions with minimal e ective conductivity is found. For monodisperse suspensions of spheres, a critical radius is found for which the electric eld is uniform throughout the composite.