The silica particles dispersed well in the rubber matrix and the mechanical properties were significantly better than those measured previously for NR containing an equivalent amount of silica and TESPT which was prepared in situ.23 A similar behavior was also observed when a high level
of TESPT pre-treated precipitated silica was used in NBR.24 In addition, the rubber reactive tetrasulfane groups of TESPT reacted with the rubber chains in the presence of accelerator to form stable covalent crosslinks or chemical bonds which increased the rubber–filler interaction. This was beneficial to the reinforcement of the rubber properties.