Generalized Bruggeman Formula for the Effective Thermal Conductivity of Particulate Composites with an Interface Layer

Combining the well-known Bruggeman theory and Nan et al. results, formulas for predicting the effective thermal conductivity of anisotropic particulate composites with an interface layer are derived. These formulas are valid for a composite material containing arbitrarily oriented ellipsoidal particles with any aspect ratio, and they can be expected to be suitable mainly for large volume fractions, when the thermal interaction between neighboring particles needs to be considered. Results of the present approach are reduced to simpler formulas for some limiting cases in the particle shape. Theoretical analysis of the effective thermal conductivity as a function of volume fraction and shape of the particles is performed. Comparison of the obtained formulas with previously reported experimental data for the effective thermal conductivity is also presented.