Kinetic study on the crosslinking process of rubbers with peroxide using oscillating rheometer

Kinetics of peroxide crosslinking process of rubber is studied in this paper. A formula is proposed to analyze this kinetics. The formula shows the relation between the rate of crosslinking and the initial peroxide concentration, V=A√<[I]0>+B[I]0where V is the rate of crosslinking measured by oscillating rheometer, [I]0 is the initial peroxide concentration, and A and B are coefficients.The rate of crosslinking is determined from the gradient of the torque curve measured by a oscillating rheometer. The first term of this equation represents that the rate of crosslinking between a double bond on a polymer chain and a carbon radical on other polymer chains, the rate of additional reaction, is propotional to the root of the initial peroxide concentration. The second term of this equation represents that the rate of crosslinking between two carbon radicals on polymer chains, the rate of radical terminations, are proportional to the initial peroxide concentration.Calculated values of A/B for SBR, BR, NBR, and HNBR by varying peroxide concentration clarified that mechanism of crosslinking differed depending on the kinds of rubbers. SBR and BR were mainly crosslinked by the addition reaction, while NBR and HNBR were mainly crosslinked by the radical termination.