Butyl rubbers are copolymers of isobutylene with a small amount of isoprene, also known as isobutylene-isoprene rubber (IIR). Its high degree of gas impermeability has allowed IIR to find widespread use in inner tubes, air cushions, pneumatic springs, and similar products. When IIR is vulcanized with a resin cure system, the resulting product contains vulcanized networks with very good heat resistance. As a result, IIR has found use in the expandable bladders for automatic tire curing presses. The least unsaturated butyl is good for electrical insulation (ozone resistance) and for rubber sheeting (weather resistance). The dampening and shock absorption property has led to butyl rubber applications in automotive suspension bumpers and the fabrication of body mounts.
