Technological Comparison of Polychloroprenes

Hargreaves, C. A., Chapter 4C of Polymer Chemistry of Synthetic Elastomers Part 1 (Eds. J. P. Kennedy and E. G. M. Tornqvist), Interscience, New York (1%8). 

Hargreaves, C. A. and Thompson, D. C., 2-chlorobutadiene polymers Chapter in Encyclopaedia of Polymer Science and Technology, Vol. 3, Wiley, New York (1965). 

Isobutene has the distinction of having been the first alkene to have been polymerized to a high molecular weight polymer whilst the polymer was the first polyalkene to have been commercially developed. Whereas polyethylene was first prepared (unexpectedly) in 1933 with pilot plant production not commencing until the 1st September 1939, and polypropylene not discovered until the early 1950s, the IG Farben company were as early as 1932 disclosing details of polyisobutene manufacture to the Standard Oil Co under a research agreement. 

These polyisobutenes are rubbery but, because of their saturated structure, they can not be cross-linked by conventional systems such as those based on sulphur nor could they be cross-linked by peroxides. As a consequence the materials exhibit high cold flow and creep and are thus unsuitable in most conventional rubber applications. This deficiency was eventually overcome by Thomas and Sparks and their co-workers at Standard Oil by copolymerization of the isobutene with a small quantity of a diene monomer to give a polymer which may be vulcanized by conventional sulphur-based systems. Although 

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