液状ポリブタジエンのペルオキシド架橋

概要

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Liquid PB having various structures were cured with dicumyl peroxide.Curing curve, infrared spectrum, degree of swelling, crosslinking density, crosslinking efficiency, double bond concentration, double bond consumption efficiency and sol-gel fraction were measured. The ratio of network chain formation per radical to double bond consumption per radical was also calculated.The vulcanizate of 1, 2-PB was very high in crosslinking density and consumption of double bond. The crosslinking is supposed to proceed by a chain reaction propagated with pendant vinyl groups.The vulcanizate of 1, 4-PB had a small crosslinking density and a large amount of residual unsaturation. The curing is presumed to proceed by an abstraction of allylic hydrogens.1, 2-PB containing terminal acrylic groups showed the highest curing rate and crosslinking density. The molecular weight between crosslinks approximated to a butadiene unit.Hydrogenated 1, 2-PB containing acrylic end groups were also cured very rapidly, but the crosslinking density was moderate.It is supposed that highly active acrylic end groups react by a chain mechanism to yield secondary large molecules, which then crosslink intra- and intermolecularly.