Telechelic Poly(butadiene) Diacrylate for the Radical Cure of Elastomers

摘要

Coagents are multifunctional compounds that react readily with radicals and promote crosslinking between polymer chains. For this reason, they are typically used with organic peroxides to cure elastomers and improve the physical properties of the resulting vulcanizate. Coagents are differentiated by structure and commonly classified by their influence on cure kinetics and the final state of cure. Type Ⅰ coagents include the very reactive acrylate and methacrylate grades, and show a marked increase in both the rate and state of cure. Polymeric coagents, typically high vinyl poly(butadiene), are Type Ⅱ coagents which primarily influence the state of cure. A unique poly(butadiene) diacrylate has been developed which includes both Type Ⅰ and Type Ⅱ structures. The polymeric coagent (Sartomer SR307) is based on a high vinyl poly(butadiene) backbone and contains acrylate functionality. The resulting telechelic polymer can be effectively used to promote high crosslink density in the radical cure of unsaturated elastomers. The structure-property relationships of this new coagent are explored. The poly(butadiene) backbone provides exceptional solubility in hydrocarbon elastomers compared to conventional monomeric Type Ⅰ acrylate coagents. Crosslink density and modulus are improved when compared to 1,4-butanediol diacrylate and trimethylolpropane triacrylate, while scorch safety is extended. The synergistic qualities of the high vinyl and acrylate structures are highlighted by comparison to other polymeric coagent types, and blends of high vinyl poly(butadiene) and monomeric acrylates.