HTPB-Grafted Nano-Silica for Use in SBR Compounds via Solution and Melt Mixing

The processing conditions strongly affect the properties of the vulcanized rubber goods. In this regard, proper dispersion of reinforcing fillers, especially in nano-scale, has a crucial role. In the current paper, fumed nano-silica was modified by grafting hydroxyl-terminated polybutadiene (HTPB) and dispersed in SBR via solution and melt mixing. Vulcanization characteristics, mechanical and dynamic properties of SBR/silica nano-composites prepared by two methods were discussed. Morphology of both vulcanizates containing 6wt% nano-silica showed that filler particles are homogenously distributed throughout the SBR matrix in the form of nano-clusters with sizes less than 100 nm. However, samples prepared by solution mixing showed slightly better dispersion than melt mixing. Modification of silica by HTPB grafting removed the adverse effect of silica in slowing-down the vulcanization rate of compounds. Mechanical and dynamic-mechanical properties of both samples demonstrated proper reinforcement of rubber, with slight advantage of solution over melt-prepared samples. It was concluded that HTPB grafting method modifies nano-silica to the extent that it can be used in melt mixing as well as solution mixing to obtain proper mechanical reinforcement in SBR vulcanizates.

Keywords:

Rubber , Mixing Process , HTPB-grafted Nano-silica , SBR