Influence of silane coupling agent on interface interaction and properties of nano-silica / silicone rubber composites

The nano-silica was surface modified by single functional coupling agent,hexamethyldisilazane( HMDS) and bifunctional coupling agent,γ-methacryloxypropyltrimethoxysilane( KH-570) respectively,the modified silica / methyl vinyl silicone rubber( MVQ) composites were prepared,the modification effect of coupling agents and dispersion of modified silica in MVQ were studied and characterized,and the influence of coupling agents on bound rubber,dynamic mechanical properties,crosslinking density and tensile properties was investigated. The results showed that HMDS and KH-570 had been grafted onto silica respectively,and both modified silicas had the same mole grafting ratio. A certain amount of HMDS modified silica aggregated when it was dispersed in rubber,but KH-570 modified silica dispersed well and part of it dispersed in primary level,which indicated better compatibility between particles and matrix. At lower strain,the storage modulus( G') and loss factor( tan δ) of the modified silica filled composites decreased,G' of KH-570 modified silica filled composites was lower than that of HMDS modified system,but tan δ higher. At higher strain,the G' of composites filled with silica or modified silica tended to be consistent,and tan δof KH-570 modified composites was lower than that of HMDS modified system. Modified silica filled composites had higher crosslinking density and tensile properties,the crosslinking density and tensile properties of the KH-570 modified system was higher than those of HMDS modified system.