An investigation into the mechanism by which ethylene thiourea (ETU) cross-links polychloroprene in combination with zinc oxide (ZnO) was undertaken. This was achieved through an examination of the mechanisms of cross-linking polychloroprene rubber (CR) with ETU and ZnO separately and in unison. Spectroscopic and physical characterisation techniques were employed to probe the cross-linking mechanisms of CR using other standard rubber accelerators and model compounds with analogous structures and functionalities to ETU. These investigations have resulted in the proposal of a new mechanism by which ETU and ZnO can synergistically cross-link polychloroprene, in addition to providing new evidence to support concomitant mechanisms already published for cross-linking polychloroprene.

Controlled polymerization of 2-chloro-1,3-butadiene using reversible addition-fragmentation chain transfer (RAFT) polymerization has been demonstrated for the first time. 2-Chloro-1,3-butadiene, more commonly known as chloroprene, has significant industrial relevance as a crosslinked rubber, with uses ranging from adhesives to integral automotive components. However, problems surrounding the inherent toxicity of the lifecycle of the thiourea-vulcanized rubber have led to the need for control over the synthesis of poly(2-chloro-1,3-butadiene). To this end, four chain transfer agents in two different solvents have been trialed and the kinetics are discussed. 2-Cyano-2-propylbenzodithioate (CPD) is shown to polymerize 2-chloro-1,3-butadiene in THF, using AIBN as an initiator, with complete control over the target molecular weight, producing polymers with low polydispersities (M w /M n < 1.25 in all cases).