硅烷偶联剂对纳米二氧化硅/硅橡胶复合材料界面作用及性能的影响

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

利用单官能团偶联剂六甲基二硅氮烷(HMDS)及双官能团偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)分别对纳米Si O2进行表面改性,制备了改性Si O2/甲基乙烯基硅橡胶(MVQ)复合材料,研究了2种偶联剂对Si O2的改性效果,表征了改性Si O2在MVQ中的分散状态,且考察了2种偶联剂对复合材料结合胶、动态力学性能、交联密度及拉伸性能的影响。结果表明,HMDS和KH-570都能实现对Si O2改性接枝,且2种改性Si O2具有相同的摩尔接枝率;HMDS改性Si O2分散于基体中,且存在一定量团聚体,而KH-570改性Si O2的分散性较好,部分达到原生粒子级分散,颗粒与基体相容性提高;低应变条件下,Si O2经改性后,复合材料的储能模量(G')和损耗因子(tanδ)下降,且KH-570改性体系的G'低于HMDS改性体系,而tanδ高于HMDS改性体系;在高应变条件下,未改性与改性Si O2/MVQ复合材料的G'趋于一致,而KH-570改性体系的tanδ低于HMDS改性体系;改性Si O2/MVQ复合材料具有更高的交联密度和拉伸性能,且KH-570改性体系的交联密度和拉伸性能均高于HMDS改性体系。

The nano-silica was surface modified by single functional coupling agent, hexamethyldisi- lazane （HMDS） and bifunctional coupling agent, T-methacryloxypropyltrimethoxysilane （ KH-570 ） re- spectively, the modified silica/methyl vinyl silicone rubber（MVQ） composites were prepared, the modi- fication effect of coupling agents and dispersion of modified silica in MVQ were studied and character- ized, 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 modi- fied silica filled composites decreased, G＇ of KH- 570 modified silica filled composites was lower than that of HMDS modified system, but tan 8 higher. At higher strain, the G＇ of composites filled with silica or modified silica tended to be consistent, and tan 8 of KH-570 modified composites was lower than that of HMDS modified system. Modified silica filled composites had higher crosslinklng density and ten- sile properties, the crosslinking density and tensile properties of the KH-570 modified system was higher than those of HMDS modified system.