The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances VI. Factors Influencing Cyclic Sulfide Formation in the Reaction of Sulfur with Polyisoprenes

Abstract

Abstract Cyclic Sulfides are to a large extent secondary products of the reaction of primarily formed intermolecular polysulfides with polyisoprene hydrocarbon, and undue prolongation of the time of reaction of sulfur with polyisoprenes favors cyclic sulfide formation and so reduces the cross-linking efficiency of the sulfur. Various accelerating substances markedly increase the cross-linking efficiency, either by permitting shorter reaction times to be employed, or by promoting a cross-linking rather than a cyclizing reaction of the sulfur. Thiuram disulfide accelerators in the absence of sulfur bring about cross-linking, the linkages being of C—S—C type rather than C—C.