The morphology and properties of silica nanoparticles synthesized by sol-gel reaction in elastomer matrix

In our studies the influence of different dispersing agents f.e. alkylammonium bromide, chloride, octadecylamine, magnesium stearate on the synthesis and character of silica particles prepared by a sol-gel reaction was investigated. The silica with different surface morphology was synthesized from tetraethoxysilane (TEOS) in suspension medium - decane (an appropriate model for the elastomer). The character and structure of used dispersants strongly interacted on the shape, the particle size distrbution and morphology of synthetized silicas. In comparision the reaction in the presence of dispersants was conducted "in-situ", directly, in elastomeric medium. For this purpose the mixtures of hydrogentated butadiene-acrylonitrile HNBR and ethylene-propylene rubbers EPM containing different amount of tetraethoxysilane and dispersants were prepared. Before the vulcanization the rubber mixtures were swelled in atmosphere of carbon dioxide or were allowed to stand in atmosphere with high moisture 70% to catalyze the sol-gel reactions. The analysis of SEM images of the vulcanisates showed the presence of silica particles synthesized "in-situ" in elastomer matrix. We observed the influence of TEOS addiction on the crosslink density of elastomers and mechanical properties.