SBR NANO-COMPOSITES REINFORCED BY HTPB GRAFTED NANOSILICA

Nano silica has demonstrated great potential to reinforce styrene butadiene rubber (SBR) compounds, if proper micro-structure of filler develops in the rubber matrix. In this study, fumed silica was modified by grafting hydroxy-terminated polybutadiene (HTPB) as a liquid rubber onto the surface of silica particles via toluene diisocyanate (TDI) bridging. This chemical modification allowed for dispersion of silica in nano-meter scale as well as chemical bonding of filler particles to rubber matrix during vulcanization of compound. Morphology, mechanical and dynamic-mechanical properties of nano-composite was compared to unfilled gum sample. The results showed that the nano-silica particles are homogenously distributed throughout the SBR matrix in the form of nano-clusters with an average size of about 48 mm for silica content of 6 wit%. By addition of small amount of this grafted nano-silica, tensile strength, elongation and energy at break were greatly enhanced compared to gum compound. Also, storage modulus and the activation energy of relaxation of SBR nano composite are increased compared to the SBR gum. This grafting method is promising in modification of nanosilica and its application in rubber compounds.

Keywords:

Nano-silica , SBR , grafting , micro-structure , mechanical reinforcement