Macroscopic loss factors are derived for a sea-island type of polymer alloy containing many ellipsoidal island-particles whose semi-axes are different from each other by using the equivalent inclusion method combined with the Mori-Tanaka theorem. In the analysis, Eshelby tensor for the particle is rearranged in the form of a function of Poisson's ratio of the matrix multiplied by the geometrical factor which is a function of the only aspect ratios of particle. Consequently, three macroscopic loss factors can be expressed by the geometrical factor successfully.
