天然橡胶/改性气相法白炭黑纳米复合材料的制备

Preparation of Natural Rubber/Modified Fumed Silica Nano-Composites

用间苯二酚与六亚甲基四胺络合物（RH）对气相法白炭黑进行表面改性，产物与天然橡胶混合，通过混炼和硫化制备了天然橡彬改性气相法白炭黑（NR／M-silica）纳米复合材料．采用力学性能测试、交联密度测定、透射电镜、差示扫描量热、红外光谱和X射线光电子能谱等手段研究了该纳米复合材料的结构和性能，并探讨了RH改性气相法白炭黑补强天然橡胶的机理．结果表明：M-silica对NR硫化胶的补强效果明显优于未改性的气相法白炭黑，当M-silica用量为4％-10％时，硫化胶的力学性能最佳；M-silica在橡胶基体中分散良好，硫化胶的交联密度和玻璃化温度升高；在改性剂RH作用下，白炭黑中的Si-O键和硅羟基的红外光谱特征吸收峰发生明显的蓝移，且O原子的结合能发生明显的变化，表明白炭黑表面的硅羟基与RH受热后形成的间苯二酚甲醛树脂中的酚羟基之间形成了明显的氢键作用．

Fumed silica was surfacely modified with resorcinol and hexamethylenetetramine complex （RH）, and the product was then reacted with natural rubber （NR） to prepare NIL/modified fumed silica （NR/M-silica） nanocomposites via a mixing and curing process. Moreover, the structure and properties of NR/M-silica nano-composites were investigated by mechanical testing, crosslinking density determination, TEM, DSC, FTIR and XPS, and the reinforcement mechanism of M-silica for natural rubber was also discussed. The results show that M-silica has grea- ter reinforcement effect on NR vulcanizate than the common fumed silica, that the comprehensive mechanical properties of NIL/M-silica nano-composite vulcanizates are optimum at a M-silica content of 4% - 10%, that M-silica well disperses in rubber matrix, that both the crosslinking density and the glass transition temperature of the vulcanizate increase, and that, with the addition of modifier RH, there occurs hydrogen bonds between the silicon hydroxyl groups of fumed silica surfaces and the phenol hydroxyl groups of resoreinol formaldehyde resin formed by heating RH, because the characteristic absorption peaks of Si-O bond and silicon hydroxyl group of fumed silica obviously blue-shift and because the binding energy of O atom obviously changes.