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PAPER WITHDRAWN-A Benzoxazole Sufenamide Accelerator: Its Properties and Implication in Rubber Vulcanization Mechanism
Guangzhuo Rong, Yusheng Chen, Lei Wang, Yi Pang
Department of Chemistry, University of Akron
Vulcanization is a chemical process1 that converts a soft and tacky rubber into harder and more durable materials with greatly improved resistance to wear and abrasion.2 In the tire industry, the economically most important method remains to be the sulfur vulcanization in the presence of various vulcanization accelerators.3 Benzothiazole sulfenamide derivatives TBBS are among the most widely used accelerators, due to their desirable feature of “delayed vulcanization.” Benzothiazole sulfonamides, however, often show weakness in regard to reversion stability, which causes the deterioration in mechanical and physical properties of the resulting rubber products. Despite the economic importance of the reaction, some fundamental questions remain in the vulcanization mechanism.
Herein, we have synthesized a benzoxazole-2-sulfenamide derivative TBBOS, which is shown to be a useful vulcanization accelerator. In comparison with TBBS, compound TBBOS revealed similar “delayed vulcanization” but with improved anti-reversion. We also synthesized the related zinc complexes, whose activity in vulcanization shed some light on the vulcanization mechanism.
1. Porter, M. Vulcanization of Rubber. In Organic Chemistry of Sulfur, Oae, S., Ed.; Plenum Press: New York, 1977; pp 71-118.
2. Coran, A. Y. Vulcanization. In The Science and Technology of Rubber, 3rd ed.; Mark, J. E., Erman, B., Eirich, F. R., Eds.; Elsevier: New York, 2005; pp 321-366.
3. The Vanderbilt Rubber Handbook; 14th ed.; R. T. Vanderbilt Company, Inc.: Norwalk, 2012