Effect of the functional group of silanes on the modification of silica surface and the physical properties of solution styrene-butadiene rubber/silica composites

Abstract

ABSTRACT Silica compounds were prepared using non-functionalized solution styrene-butadiene rubber (SSBR) to investigate effect of the functional group of silanes on the silica modification and properties of SSBR/silica compounds. Bis-[3-(triethoxysilyl)propyl]disulfide (TESPD), 3-mercaptopropyltriethoxysilane (MPTES), 3-aminopropyltriethoxysilane (APTES), vinyltriethoxysilane (VTES), and 3-chloropropyltriethoxysilane (CPTES) were used as silane agents. Bound rubber contents and vulcanizate structures were analyzed, and physical properties, cure characteristics and viscoelasticities were evaluated. MPTES and TESPD have chemically reactive functional groups with rubber chain. Particulary, as thiol group is more reactive than disulfide, the filler–rubber interaction is outstanding when applying MPTES. The bound rubber content of the MPTES applied compound was 30% higher. Vulcanizate structure analysis exhibited that the filler–rubber interaction of the MPTES applied compound is more than twice as high. As amino group of APTES can form hydrogen bonds with other amino or silanol groups on silica surface, strong filler–filler interaction which leads to easy agglomeration and accelerator adsorption, resulting in flocculation and marching. VTES cannot hydrophobize silica surface owing to its short carbon chain. Therefore, the compounds that apply APTES or VTES had high Payne effect, indicating poor silica dispersion. CPTES has polar functional group but behaves as covering agent because of its weak interaction with rubber.