Improved mechanical properties of silica reinforced rubber with natural polymer

Silica reinforced elastomers are widely used in various rubber applications. Natural protein polymer improves the mechanical properties of silica reinforced rubber. The improvement is demonstrated in three systems including silica, silane added silica and silane coated silica rubber composites. The tensile strength shows a maximum with an optimum amount of protein and the modulus increases with increasing amount of protein. The curing time decreased and crosslink density increased with increasing loading of hydrolyzed protein. The alkaline protein is able to reduce the negative effect of acidic silica on vulcanization. The hydrolyzed protein/silica composites show an increase in filler reinforcement through the increase of total crosslinks from chemical and physical crosslinks. Hydrolyzed protein also exhibit ability in reducing loss tangent compared to silica particles for damping applications. Thermal stability study indicates the composites are stable up to 200 degrees C in air. Current study shows a complementary effect of silica and hydrolyzed protein in rubber.