Improving thermal oxidative aging resistance and anti-reversion property of natural rubber by adding a crosslinking agent

The reversion during the curing and the poor thermal oxidative aging resistance of natural rubber are two main problems for its use as a tire tread. To solve the problems, a crosslinking agent, 1,6-bis(N,N '-dibenzyl thiocarbamoyl dithio)-hexane (DBTH), is added into natural rubber/carbon black composites. DBTH can increase the crosslink density, improve the mechanical properties and thermal oxidative aging resistance of the composites. The composites with DBTH can maintain good wet-skid resistance after thermal oxidative aging. When 0.2 phr DBTH is used to substitute 0.1 phr sulfur and 0.1 phr accelerator in a natural rubber/carbon black composite, the reversion during the curing is reduced and the DIN abrasion decreases by 6%, while the modulus and hardness of the composite keep close to the original. Besides, after thermal oxidative aging at 100 degrees C for 48 h, the rate of change of stress at 300% strain of the composite decreases by 27% with the substitution of DBTH.