The aggregation structure and mechanical properties of liquid silicone rubber, polyurethane (PU), and epoxy (EP) blends were studied. The molecular structure was evaluated by FTIR, and the intermolecular interaction of the three-phase polyblends was measured by dynamic mechanical analysis. The mechanical properties, including the tension, compression, shear, and tear performance, were measured by a material testing system. From the relationship between the intermolecular interaction and mechanical properties, we found that the aggregation structure of the three-phase blends was influenced by the reaction between silicone and PU, silicone and EP, and PU and EP, which resulted in a change of the, crosslinking density and an interpenetrating polymer network structure. Thus, the dominant three-phase mechanical properties are closely related to the aggregation structure. (C) 2003 Wiley Periodicals, Inc.