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Keywords:

  • rubber;
  • crosslinking;
  • elastomers

ABSTRACT

A benzoxazole sulfenamide and its related zinc compound were synthesized and characterized, which are shown to be useful accelerators for sulfur vulcanization. In comparison with the benzothiazole accelerator, the benzoxazole sulfenamide revealed nearly no reversion, an improved feature that is desirable for tire industry. Through the synthesis of the zinc complex 9, which was assumed to be an accelerator-activator for vulcanization, the study aimed to shed some light on the vulcanization mechanism. The crystal structure of the zinc complex 9 showed that two benzoxazole-2-thiol ligands were attached to the zinc center in different isomeric forms, with one in the thio form (linked via sulfur atom) while the other in thio–keto form (linked via nitrogen atom). Lack of the vulcanization accelerator activity from 9 led to the assumption that the sulfurating species might be zinc complexes containing only one benzoxazole-2-thiol ligand. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39699.