New Elastomers by Reactive Processing. Part II. Dynamic Vulcanization of Blends by Trans-Esterification

Abstract

Abstract The dynamic vulcanization of a rubbery acrylate copolymer (ACR) (the dispersed phase) during its mixing with NBR (the continuous phase) can produce a millable specialty elastomer alloy. The ACR polymer can be crosslinked even without having special molecular sites for vulcanization such as those of the conventional acrylate rubbers (ACM). This is possible because, under the conditions for dynamic vulcanization, the acrylate-derived ester groups themselves can be made to act as sites for vulcanization by using tin-catalyzed ester-interchange chemistry. The millable dynamic vulcanizate containing the crosslinked dispersed phase can be later mixed with curatives for the continuous phase, fillers, antidegradants, etc. and then be vulcanized (e.g., in a heated mold). Since the ACR can be completely vulcanized during the dynamic vulcanization stage of the mixing process, the usual postcuring associated with acrylate rubber (ACM) technology is not necessary. Excellent performance characteristics can be produced by using this technology.