Effects of Nano-Structure of Silica on Dynamic Properties of Styrene-Butadiene Rubber
Properties of four materials based on styrene-butadiene rubber (SBR), one without filler and the other three with the same amount but different types of silica fillers, are investigated. The fillers used are Vulkasil S and two new fillers, differing in nano-structures: specific surface area and particle aggregate morphology. All other components in the material formulations are the same as well as the procedures of material preparation. Thermal and thermo-mechanical properties of all four materials are investigated by modulated differential scanning calorimetry (MDSC) and dynamic mechanical analysis (DMA). Morphology of the materials is studied using scanning electron microscopy (SEM). The results for glass transition temperature (Tg ) of gum rubber and three filled rubbers, obtained by MDSC are for all four materials Tg = -50±1 0C, and by DMA loss tangent measurements also for all of them Tg = -29±1 0C. It indicates no significant influence of active silica fillers on the rubber network segment dynamics, in the temperature range close to Tg of SBR. But, at higher temperatures MDSC gives insights into dynamic transitions that are under the influence of filler interactions and sensitive to filler structure. The difference in Tg results obtained for the same material by MDSC and DMA can be understood in terms of different sensitivity of network segment dynamics to conditions provided by those two measuring methods.
Dragan P. Uskoković, Slobodan K. Milonjić and Dejan I. Raković
N.L. Lazić et al., "Effects of Nano-Structure of Silica on Dynamic Properties of Styrene-Butadiene Rubber", Materials Science Forum, Vol. 555, pp. 473-478, 2007