The silane (TESPD) treated silica-filled silicone rubber (SR)/natural rubber (NR) blends are studied with regard to their mechanical, thermal, and optical properties. Two grades of SR, with and without vinyl group are used and the results are compared. The effects of a vinyl functional group in SR with respect to vibration isolation property, and mechanical properties are investigated to find maximum torque, tensile strength, tensile modulus, elongation at break, hardness and tan delta. The compounds are cured with sulfur, peroxide and peroxide/sulfur combination. The results show that the presence of the vinyl group in SR helps improve the mechanical and thermal properties of the SR/NR blend. Scanning electron microscopy (SEM) photographs show that the silica particles are well dispersed in the rubber matrix. Thermal properties including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and heat resistance are also studied. It shows the presence of the vinyl group in the SR/NR blend curing with the peroxide/sulfur combination improves both mechanical properties and the vibration properties. (C) Koninklijke Brill NV, Leiden, 2011