Model Reaction of Polysulfide with Olefin

Abstract

Abstract A model polysulfide, t-butyl polysulfide (TBPS) and an olefin, cyclododecene (CDD), were used to study the reactivity of polysulfanes in silica filled rubbers. The TBPS has a similar sulfur rank and distribution as bis (3-triethoxysilylpropyl) tetrasulfide (TESPT) without the complication of reactivity of the triethoxysilyl group that would cause a loss of soluble components of the reactants and products by hydrolytic coupling. Thermal reaction between the polysulfide and olefin was investigated by following the TBPS loss in the CDD solution at 171 °C as a function of time. The loss of TBPS and the formation of reaction products during heating were followed, identified and quantified using HPLC. These include attachment of t-butyl sulfide group from the TBPS to CDD, coupling between CDD, and redistribution of the sulfur rank. It was found that after six minutes, less than 2 weight % of the sulfur in the TBPS was utilized to couple CDD molecules. Since these thermal conditions are more severe than what a rubber compound is normally subjected to, this sulfur coupling would not be expected to give a vulcanization problem during mixing. The model reaction was also followed in the presence of added peroxide or typical vulcanization ingredients. The strongest catalytic effect was seen with N-cyclohexyl-2-benzothiazolesulfenamide and zinc oxide.