Polydienes with ethylene oxide

Polychloroprenes differ from other polydienes in that conventional sulphur vulcanization is not very effective. The double bonds are deactivated by the electronegative chlorine atoms and direct reaction with sulphur is limited. The vulcanization of polychloroprenes is normally achieved by heating at about 150°C with a mixture of zinc and magnesium oxides W type neoprenes also require an organic accelerator (commonly either a diamine or ethylene thiourea) but G types cure quite rapidly without acceleration. The mode of reaction has not been established with certainty, but it is generally supposed that cross-linking occurs at the tertiary allyUc chloride structures generated by 1,2-polymerization (see Section 18.8.3) and that a 1,3-allylic shift is the first step. The metal oxides may lead to ether cross-links as follows ... 

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