Influence of Surface Modification of Silica on Curing and Mechanical Properties of Silica‐Filled Rubber Compounds

ABSTRACT An in‐depth understanding of surface modification of silica is critical for the development of high‐performance green tires. In this work, silica was modified either with the silane coupling agent bis‐(3‐triethoxysilylpropyl)‐tetrasulfide (TESPT) alone, or with a synergistic combination of TESPT/n‐octyltriethoxysilane (OTES) and TESPT/hexamethyldisilazane (HMDS). TESPT‐modified silica samples with varying degrees of surface modification were prepared, and the dual modification system achieved a higher degree of hydrophobicity than TESPT alone. Results indicated that surface grafting of silica significantly reduced curative adsorption, with N,N ′‐diphenylguanidine (DPG) exhibiting higher adsorption than N‐cyclohexyl‐2‐benzothiazolesulfenamide (CBS); TESPT in combination with modifier led to a decrease in DPG adsorption. The effects of such silica surface grafting on the cure characteristics of solution styrene‐butadiene rubber (SSBR) compounds and the mechanical properties of the resulting vulcanizates were systematically investigated. Enhanced surface modification led to increased total and chemical crosslink density, attributed to suppressed curative adsorption along with improved filler dispersion. Based on these findings, the effects of filler surface modification on the physical properties of the vulcanizates were further discussed and compared. Overall, the cure behavior and mechanical properties of silica‐filled rubber compounds are strongly influenced by the surface chemistry of silica.