Abstract:The surface characteristics of mineral fine powders will affect the reinforcement effect of mineral filler upon silicone rubber matrix, and the interfacial interaction between mineral filler and silicone rubber matrix will be the mechanical properties of silicone rubber filled with mineral fine powder. Using double liquid method the authors measured the equilibrium contact angles of the surface modified and surface_unmodified mineral fine powders of talc, quartz, granular wollastonite, fibrous wollastonite, kaolinite and ground CaCO3. According to Fowkes ' and Young's theory, the surface energy of the above mineral fine powders were calculated. The results show that surface energies, dispersion components and polar components are different for different mineral fine powders caused by differentce in composition, structure and surface group for different mineral powders. After surface modification of mineral powders, their surface energy will decrease, and the extent of decrease of surface energy will be affected by kinds and concentrations of coupling agents. Based on the surface energy, the interfacial tension (γSL) and the adhesive work (Wa) between mineral fillers and silicone rubber were calculated. Analyzing and comparing Wa,γSLand tension strength (σB) of mineral powder silicone rubber composite materials reveal that there exists positive correlation between (Wa/γSL) and (σB). In other words, the larger (Wa/γSL) the composite materials, the stronger the interfacial interaction between mineral fillers and silicone rubber matrix, the better the mechanical properties of composite materials. It is belived that the rule is suitable not only to unmodified and modified mineral powders in silicone rubber matrix but also to other rubber matrix. The paper has also made a deepgoing theoretical and experimantal analysis of this rule.