Thiophosphoryl disulfides as crosslinking agents for chloroprene rubber

The objective of this investigation was the determination of a suitable substitute for ethylene thiourea (ETU), a well-known vulcanizing agent for polychloroprene rubber (CR). Unfortunately, ETU is a potent carcinogenic compound, and so its replacement is needed. The efficacy of several thiophosphoryl disulfides as crosslinking agents for CR, either alone or in combination with other compounds, was examined. It was shown that bis(diisopropyl)thiophosphoryl disulfide (DIPDIS) and bis(dicyclohexyl)thiophosphoryl disulfide (DCHDIS), being ecofriendly, could be replacements. Additionally, these thiophosphoryl compounds were shown to provide significant antioxidant protection. CR vulcanizates containing DIPDIS or DCHDIS exhibited higher tensile strengths than those containing ETU. Bis(3-ethoxysilylpropyl) tetrasulfide imparted to CR vulcanizates a notable modulus, which was comparable to that obtained with ETU-cured products. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1913–1919, 2004