Chapter 6 Butyl and halogenated butyl RubbersW.D.GUNTER Polysar Ltd, Sarnia, Ontario, CanadaSUMMARY Butyl and halogenated butyl Rubbers are predominant among elastomers from which respectively, tyre inner tubes and curing bags, and tubeless tyre inner liners, are made. These are their primary aplications, but various grades of the two classes of rubbers are also widely used in products as dissimilar as sealants pipe wrapping systems, vehicle body mounts phamaceutical bottle closures acid resistant tank linings, reservoir and roofing membranes, and chewing gums.This chapter presents a brief treatment of the history, chemistry, manufacture, and aplications technology of butyl and halobutyl rubbers, itemising siglificant developments and current trends. Most of the formulations listed do not contain ingredients that are known to be hazardous, but reference is made to lead oxides and substituted dioximes as curatives with the expectation that compounders will give due consideration to toxicological factors when selecting compound ingredients.1. Introduction.1.1 Distinguishing Properties of butyl rubbers Standard or unmodified grades of butyl rubber are linear, amorphous, gel-free copolymers of isobutylene and isoprene. Individual grades differ from each other in functionality, the level of unsaturation varying with the ratio of isoprene to isobutylene, raw polymer viscosity (a function of molecular weight) and properties of the stabilisers, if any, incorporated during manufacture.
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