Analysis of network structure formed in styrene-butadiene rubber cured with sulfur/TBBS system

Several styrene-butadiene rubber (SBR) compounds were prepared with different cure systems based on sulfur and TBBS (N-t-butyl-2-benzothiazole sulfenamide), varying the amount of sulfur and accelerator between 0.5 and 2.5 phr in the formulation. Torque curves, measured with a moving die rheometer at temperatures at 433 K, were used to characterize the vulcanization. The time to achieve the maximum torque, t(100%), was evaluated for each sample, and this time was set to vulcanize sheets at 433 K. The density and type of elastically active crosslinks of each cured sample were evaluated by means of swelling measurements and were related to the vulcanizing system. Finally, the rheometer data were analyzed considering the network structure formed during vulcanization. (c) 2006 Wiley Periodicals, Inc.