Novel curing systems for chlorosulfonated polyethylene

Abstract

SynopsisPolyfunctional alcohols, acyclic, cyclic, and heterocyclic imines, and organotin oxides have been studied as crosslinking agents for chlorosulfonated polyethylene. Mechanisms for the crosslinking reactions involving the sulfonyl chloride moiety have been proposed. Differences in curing activity have been correlated with structural modifice tions of the curing agents consistent with classical chemical reactions for nonpolymeric systems. Of the curing systems examined, the polyols provide nontoxic, low cost, safeprocessing formulations offering excellent physical properties which have found use in practical commercial applications.The curing of chlorosulfonated polyethylene elastomers, commercially available as Hypalon -20, -30, and -40 (Hypalon is the registered trademark of E. I. du Pont de Nemours and Co., Inc.), to obtain optimum physical properties requires the use of both a metal oxide and a sulfur accelerator in the most commonly used systems. Metal sulfonate crosslinks are formed by hydrolysis and neutralization reactions' [eqs. (l), (2), and (3)]. The role of the sulfur accelerator appears to involve the formation of sulfur crosslinks through chain unsaturation arising from dehydrochloriDation [eqs. (4) and ( 5 ) ] . This is supported by the observation that the omission of accelerator results in inferior vulcanizates,' and the fact that the sulfonamide formed by the reaction of a chlorosulfonated polyethylene with a dialkyl anline can be cured with the sulfur curing systems used for butyl rubber. Since this polymeric derivative is devoid of reactive sulfonyl chloride cure sites, sulfur crosslink formation alone is probably responsible for vulcanization. The presence of labile chlorines, such as tertiary chlorines in a branched polymer or chlorines beta to the sulfonamide (or sulfonyl chloride) groups, is the most probable source of this unsaturation.2 where R = polymer chaiii.

Physico-mechanical and electrical properties of conductive carbon black reinforced chlorosulfonated polyethylene vulcanizates

“…The systematic study of the CSM rubber particularly filled with highly conductive carbon black has not received much attention till today. Literature study reveals that very few research works dealing with CSM rubber have been reported [1][2][3][4]. The preparation of electrically conductive polymer composites filled with conductive fillers has already been reported by several researchers [5][6][7].…”

Influence of Different Curing Systems on the Physico-Mechanical and Rheological Properties of CSM Rubber

“…Studies of CSM rubber compounds have not received much attention even though they possess good weather resistance, electrical properties and aging resistance. Few research works dealing with CSM rubber have been reported in the literature [11][12][13] . The effect of β irradiation on structural changes of CSM rubber has been studied by Foucault et al 14 .…”