The formula is: -(-CH2-C(CH3)2-)n-
A synthetic rubber, or elastomer, polyisobutylene is impermeable to air and used in many applications requiring an airtight rubber. Polyisobutylene is used in making adhesives, agricultural chemicals, fiber optic compounds, caulks and sealants, cling film, electrical fluids, lubricants (2 cycle engine oil), paper and pulp, personal care products, pigment concentrates, for rubber and polymer modification, as a gasoline/diesel fuel additive, and even in chewing gum. The first major application of butyl rubber was tire inner tubes. This remains an important segment of its market even today.
Butyl rubber was first developed in 1937, by researchers William J. Sparks and Robert M. Thomas, at Standard Oil's (which became Exxon in 1972) Linden, N.J. laboratory. Texas Petrochemicals and Lubrizol Corporation are one of the largest manufacturers of PIB in North America.
In 1950s and 1960s, halogenated butyl rubber (halobutyl) was developed, in its chlorinated (chlorobutyl) and brominated (bromobutyl) variant, providing significantly higher curing rates and allowing covulcanization with other rubbers like natural rubber and styrene-butadiene rubber. Halobutyl is today the most important material for inner tubes. The butyl rubber is vulcanized by elemental sulfur. Zinc oxide can be also used to vulcanize halobutyl.
As a fuel additive, polyisobutylene has detergent properties. When added to diesel fuel, it resists fouling of fuel injectors, leading to reduced hydrocarbon and particulate emissions. They are blended with other detergents and additives to make a "detergent package" that is blended into gasoline and diesel fuel to resist buildup of deposits and engine knock.
Polyisobutylene is used in some formulations as a thickening agent.
Rubber roof is typically referred to a specific type of roofing materials that are made of Ethylene Propylene Diene Monomer (EPDM). The crucial component for the maintenance of the quality of such roofs is to avoid using harsh abrasive materials and petroleum-based solvents for their maintenance.