Silane coupling agents sulfur functional

Silane coupling agents are widely used to improve the performance of mineral fillers in elastomer systems. The silanes most commonly used are the various sulfur-based ones and the vinyl and amino functional. The sulfides are generally used both pre-coated and in situ . The fillers most often used in conjunction with silane coupling agents are precipitated silicas and clays. The primary objective of the treatment is to improve polymer to filler bonding, although other benefits such as lower viscosity, better dispersion and reduced water adsorption are also observed. 

Chloropropyl, vinyl, and methacrylate-functional silanes on glass were only slightly better than untreated surface for adhesion to most of the rubbers. The mercaptan and amine-functional silanes have been the preferred silanes on fillers in sulfur-vulcanized rubbers. The amine gave better adhesion to natural, nitrile, and Hypalon rubbers, while the mercaptan was better with SBR, Neoprene and EPDM. The iso-thiuronium-functional silane appears to be fairly effective in bonding all rubbers—but especially SBR. Anionic or cationic styryl coupling agents were the best unsaturated silanes and contributed true adhesion to EPDM and Hypalon. 

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