Effect of Nano CaCO₃ on thermal properties of Styrene Butadiene Rubber (SBR)

Styrene butadiene rubber (SBR) as matrix was reinforced separately with 9, 15 and 21 nm sizes of CaCO₃, which were synthesized by matrix mediated growth technique. The mixing and compounding was done on two-roll mill and sheets were prepared in compression molding machine. The effect of nature and loading of nano CaCO₃ on these rubber nanocomposites was investigated thoroughly by different characterizations such as DSC, TGA, XRD, and mechanical properties. An appreciable increase in glass transition temperature has been observed from DSC study. 9 nm sizes of CaCO₃/SBR composites show more increment in Tg as compared to pristine SBR as well as different sizes of CaCO₃ filled SBR. This increment in Tg is due to restricted mobility of nano CaCO₃ filled SBR nanocomposites. XRD study of nanocomposites showed that nano CaCO₃ dispersed uniformly throughout the matrix because of the small peak at lower 2θ. This uniform dispersion of nano CaCO₃ contributes towards the higher mechanical properties of rubber composites. From TGA study, it was observed that as the size of CaCO₃ reduces the thermal stability increases as compared to pristine SBR. The other results of these rubber nanocomposites were compared with commercial CaCO₃ filled SBR.