Improving performance of natural rubber composites through the novel silica modified by a crosslinking agent

Silica dispersion and silica-natural rubber (NR) interaction are two major issues in determining the performance of a NR/silica composite in tire industry. In our research, the reaction product of 3-isocyanatopropyltrimethoxysilane and a crosslinking agent, poly(tert-butylphenol) disulphide, was used to modify silica. Then, the modified silica was added into NR by mechanical blending. The modification of silica can promote the silica dispersion and enhance silica-NR interaction. At silica loading of 50 phr, compared with the NR/pure silica composite containing 5 phr bis-(gamma-triethoxysilylpropyl)-tetrasulfide, the NR/modified silica composite exhibits 18% shorter curing time, 16% higher 300% modulus, 9% higher crosslink density and 6% lower rolling resistance with comparable abrasion resistance even reducing the amount of silane coupling agent to 2 phr. This modification of silica by using the derivative of poly(tert-butylphenol) disulphide provides a novel approach to the preparation of the high-performance NR/silica composites and the reduction of the amount of bis-(gamma-triethoxysilylpropyl)-tetrasulfide in tire tread formulations.