EFFECT OF PREVULCANIZATION ON THE RHEOLOGICAL BEHAVIOR OF NATURAL RUBBER STYRENE BUTADIENE RUBBER LATEX BLENDS/

The effect of prevulcanization on the rheological behavior of natural rubber (NR), styrene butadiene rubber (SBR) latices, and their blends was studied with special reference to shear rate, blend ratio, vulcani zing systems, prevulcanization time, and accelerator systems. The NR l atex showed a sharp increase in viscosity with increase in prevulcaniz ation time due to high extent of crosslinking. However, SBR latex show ed marginal effect on viscosity with prevulcanization time due to its low dry rubber content and low degree of unsaturation. Blends showed v ariations in viscosity according to the change in composition. The use of a single accelerator was found to have marked influence on the vis cosity of the blends compared with a combination of accelerators. Swel ling experiments were carried out in order to determine the crosslink density of the blends. The viscosity changes have been correlated with the crosslinking density of the latices and their blends. (C) 1996 Jo hn Wiley & Sons, Inc.