Sulfur-functional organosilane coupling agents — Si-69 (TESPT), Si-75 (TESPD), and a mercapto silane — that bond silica filler into rubber for tire and technical-rubber compounds.
Sulfide and mercapto silanes are sulfur-bearing organosilane coupling agents used to chemically link silica and other mineral fillers to rubber and polymer matrices. Each molecule carries hydrolyzable alkoxy groups (ethoxy or methoxy) that condense onto the filler surface at one end and a reactive sulfur function—polysulfide or thiol—that bonds to the elastomer during vulcanization at the other. That dual reactivity improves filler dispersion, raises reinforcement, and lowers rolling resistance in silica-reinforced compounds, which is why this class of silane coupling agent is central to tire tread and technical-rubber formulation. RawSource sources these coupling agents in bulk—drums, totes, and container loads—to specification.
Selection follows the sulfur chemistry and the cure system. Bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT, comparable to Si 69) carries four sulfur atoms, so it both couples silica and contributes sulfur to the crosslink network, making it the workhorse for silica tread and high-reinforcement compounds. Bis[3-(triethoxysilyl)propyl] disulfide (TESPD) provides a shorter, more stable disulfide bridge and lower free-sulfur content, which reduces scorch tendency and widens the processing window where premature crosslinking is a concern. (3-Mercaptopropyl)trimethoxysilane (MPTMS) is a mercaptosilane whose free thiol delivers high coupling efficiency at lower loadings, suited to silica composites, sealants, and mineral-filled thermosets. The methoxy grade (MPTMS) hydrolyzes faster than the ethoxy polysulfides; match the alkoxy group and sulfur rank to your mixing temperature and cure package.
These products are for industrial and professional use only. Consult the current SDS for each grade and confirm compatibility with your polymer, filler, and cure system—along with regulatory status for your process and jurisdiction—before specifying.
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