Effect of Long-Chain Branch of Poly(methyl acrylate-co-1-octene) on the Vulcanization and Mechanical Properties

Abstract

The unsaturated linear (UL) copolymer of methyl acrylate (MA), 1-octene, and allyl glycidyl ether (AGE) and the long-chain branch (LCB) copolymer of MA, 1-octene, and 1,7-octadiene were synthesized, respectively, via AlCl3-catalyzed radical copolymerization, and then both UL and LCB copolymers were vulcanized using dicumyl peroxide (DCP) curing system. For UL copolymer, cross-linking heat first increases with DCP dosages and then decreases when DCP dosages increases further to 2.5, that is quite reasonable to relate with cross-link and degradation reactions during vulcanization. However, the reaction heat flow curves of DCP-LCB curing system with DCP dosages ranging from 1.5 phr to 3.5 phr exhibit a bimodal-like “crosslinking” endotherm, suggesting a two-stage reaction of intramolecular cross-linking and intermolecular cross-linking. Results from dynamic mechanical analysis and tensile tests confirm that LCB copolymers are propitious to form effective networks at low DCP dosages and to keep the vulcanized...