Abstract
Diene rubbers such as BR, SBR and NBR were found to be easily vulcanized by heating with p-phenylene-3, 3'-disydnone (PDS) at 180°C for 20 to 40 minutes. The PDS vulcanizate was excellent in heat resistance under the condition of oven aging. Tensile strength and elongation at break of the PDS vulcanizate of NBR with carbon black was 217kg/cm2 and 590%, respectively. A mechanism was proposed for this nonsulfur vulcanization, where disydnone dipole forms a pyrazoline ring by 1, 3-dipolar cycloaddition reaction with carbon-carbon double bond of rubber to give the vulcanizate. Sufficient vulcanizate was not obtained from gum stock, because bubbles were produced during the vulcanization due to the generation of carbon dioxide. However, this bubbling was inhibited by the mixing with carbon black or calcium oxide.
