Reactions of Isoparaffins with Sulfur and DI-t-Butyl Peroxide

Abstract

The role which sulfur plays in the peroxide vulcanization of polyisoparaffins has been investigated. The problem was studied by using a system in which 2,4dimethylpentane is a model for the polyisoparaffin chain. Two alternative reaction mechanisms are proposed. Work with the model system shows that polysulfides formed from the isoparaffin are the dominant products. By analogy it is inferred that polysulfide linkages join the polyisoparaffin chains, preferably at what were formerly tertiary hydrogen sites. Nearly all of the high boiling products are disulfides and, or, polysulfides, and these total at least a 28 mole per cent yield based on peroxide charged. Thus, it is indicated that sulfur plays a major role, and does not simply prevent minor side reactions. Study of the gaseous reaction products indicates that sulfur does not alter the course of the initiation step. A reaction mechanism is proposed which is consistent with literature and with our experimental work.

Readily Curable Chlorinated Poly-α-olefins and Ethylene-α-olefin Copolymers

“…Since these copolymers contain no functionality for the traditional methods of vulcanization, specialized vulcanization procedures were developed utilizing primarily peroxide curing agents (7 7, 27,24,37,44,52) but also agents such as trichloromelamine (30), trichloromethanesulfonyl chloride (53), and octachlorocyclopentene (54). These direct curing methods impose some limitations in the choice of compounding ingredients, processing methods, and end use characteristics.…”