Novel Thiazole binary system for effective sulphur vulcanization of natural rubber

Investigations have been carried out on the synergistic activity of binary accelerator systems in vulcanization of natural rubber, keeping in mind that such mixed systems can effectively prevent pre-vulcanization, permit the vulcanization to be done at a lower temperature in a shorter time and produce a vulcanizate with superior mechanical properties compared to those of reference mix cured with a single accelerator. In the present study a novel series of benzothiazoloylthiazoles (BET) were used as a secondary accelerator along with Cyclohexylbenzthiazylsulfonamide(CBS), Mercaptobenzothiazole(MBT) or Zincdithiocarbamate (ZDC) in the sulfur vulcanization of natural rubber. The effect of these secondary accelerators on the cure and mechanical properties were studied and was found to be improved when compared to the reference mixes. These SAs were found to be effective in reducing the cure time by 75% with a minimal amount of 0.5 phr, but commercially available SAs like thioureas and tetramethylthiuram disulfide (TMTD) were reported to show reduction in cure time only by increasing the amount of SA. Chemical characterization was carried out by determining the total crosslink density.