KINETICS OF SULFUR VULCANIZATION OF NR, BR, SBR, AND THEIR BLENDS USING A RHEOMETER AND DSC

The relationship between vulcanization reactivity and chemical structu re was studied using a rheometer and DSC for natural rubber (SMR 5CV), butadiene rubber (BR 01), styrene-butadiene rubber (SBR 1501), and th eir blends. The overall rate of the vulcanization was SBR > BR > NR. T his was the same trend as the number of allylic hydrogens in the stati stical repeat unit of the rubber used. Because the corresponding rate constant for an allylic hydrogen was very similar regardless of the ru bbers, it was found that the vulcanization condition for a compounded rubber could be predicted by comparing the number of allylic hydrogens . The activation energy of the vulcanization was calculated for each r ubber also. (C) 1996 John Wiley & Sons, Inc.