Butyl rubber is a synthetic elastomer made by combining isobutylene and isoprene. It was the first rubber to be synthesized. It has good shock absorption characteristics and low moisture and gas permeability and is used in many commercial applications

Due to its low gas and vapor permeability, butyl rubber is an important material in the manufacturing of tubeless tires, inner tubes, sports-ball bladders, glove-box gloves, etc. As a waterproofing material, it is applied as a liner in tanks and ponds. It is used as a patching material for membrane roofs and as a sealant for insulated windows. As a vibration dampener, butyl rubber is used for shock mounts, suspension bushings, and car- and truck-body mounts.

Butyl rubber is available as slabs, sheets, and tapes, and as an adhesive/sealant in tubes. The material can be molded (by transfer, injection, and compression molding processes) and extruded. It is used to make gaskets, hoses, O-rings, etc.