Zinc Oxide Crosslinking Chemistry of Halobutyl Elastomers—A Model Compound Approach

Abstract

Abstract The study of the crosslinking reactions of halobutyl rubbers with zinc oxide, conducted on low molecular weight model compounds, has brought about a thorough understanding of the chemistry of this process. It has been shown that there are two competitive processes taking place, with the major one generating the catalyst for the oligomerization reaction and producing a substantial amount of a monomeric diene. The actual crosslinking process is a cationically induced oligomerization based on carbon-carbon bond formation. The major high molecular weight product is the dimeric hydrocarbon with a small amount of trimeric product also being formed. Both the direct elimination reaction and the crosslinking process lead to the formation of dienic functional groups.