Hydrogenated Nitrile Rubber
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Hydrogenated Nitrile Rubber book
As the name might suggest, Hydrogenated Nitrile (HNBR), is produced by the catalytic hydrogenation of Acrylonitrile Butadiene copolymer elastomers, NBR. The chemical structure of NBR polymers is shown in Figure 3.1. Note in Figure 3.1 that there are generally two types of Butadiene addition to the free radical polymerization process: addition in the 1,4 position which is the bulk of the Butadiene fraction as well as addition in the 1,2 position which forms a pendant carbon-carbon double bond. To understand the resultant properties of HNBR, it is necessary to recognize both types of Butadiene addition in the formation of the NBR polymer. The 1,2-Butadiene incorporation produces a vinyl type structure, which is particularly reactive in subsequent vulcanization reactions.