Nitrile rubber (NBR), also called nitrile-butadiene rubber, an oil-resistant synthetic rubber produced from a copolymer of acrylonitrile and butadiene. Its main applications are in fuel hoses, gaskets, rollers, and other products in which oil resistance is required.
In the production of NBR, acrylonitrile (CH2=CHCN) and butadiene (CH2=CH-CH=CH2) are emulsified in water and then polymerized (their single-unit molecules linked into large, multiple-unit molecules) through the action of free-radical initiators. The amount of acrylonitrile present in the final copolymer varies from 15 to 50 percent. With increasing acrylonitrile content the rubber shows higher strength, greater resistance to swelling by hydrocarbon oils, and lower permeability to gases. At the same time, however, the rubber becomes less flexible at lower temperatures, owing to the higher glass transition temperature of polyacrylonitrile (i.e., the temperature below which the molecules are locked into a rigid, glassy state).
Nitrile rubber is mostly used where high oil resistance is required, as in automotive seals, gaskets, or other items subject to contact with hot oils. The rolls for spreading ink in printing and hoses for oil products are other obvious uses. NBR is also employed in textiles, where its application to woven and nonwoven fabrics improves the finish and waterproofing properties.
NBR is made in a hydrogenated version (abbreviated HNBR) that is highly resistant to thermal and oxidative deterioration and remains flexible at lower temperatures.
Nitrile rubber, like styrene-butadiene rubber and other synthetic elastomers (elastic polymers), was a product of research that took place during and between the two world wars. A group of acrylonitrile-butadiene copolymers, given the name Buna N, was patented in 1934 by German chemists Erich Konrad and Eduard Tschunkur, working for IG Farben. Buna N was produced in the United States during World War II as GR-N (Government Rubber-Nitrile), and subsequently the group of acrylonitrile-butadiene elastomers became known as nitrile rubber.
Learn More in these related Britannica articles:
major industrial polymers: Nitrile rubber (nitrile-butadiene rubber, NBR)Like SBR, nitrile rubber is a product of synthetic rubber research during and between the two world wars. Buna N, a group of acrylonitrile-butadiene copolymers, was patented in the United States in 1934 by IG Farben chemists Erich Konrad and…
chemical industry: Elastomers…acrylonitrile, two-thirds butadiene) to form nitrile rubber (NBR). This synthetic has different properties from other synthetics and is used for rubber hose, tank lining, conveyor belts, gaskets, and wire insulation. Acrylonitrile and styrene, together with butadiene, form a terpolymer, called ABS, which is useful for high-impact-strength plastics.…
rubber: The rise of synthetic rubberneoprene), a high-strength oil-resistant rubber; nitrile rubber (NBR), an oil-resistant copolymer of acrylonitrile and butadiene synthesized by Erich Konrad and Tschunkur in 1930 and known as Buna N in Germany; and butyl rubber (IIR), a copolymer of isoprene and isobutylene discovered in 1937 by the Americans R.M. Thomas and W.J.…
Rubber, elastic substance obtained from the exudations of certain tropical plants (natural rubber) or derived from petroleum and natural gas (synthetic rubber). Because of its elasticity, resilience, and toughness, rubber is the basic constituent of the tires used in automotive vehicles, aircraft, and bicycles. More than half of all rubber…
Butadiene, either of two aliphatic organic compounds that have the formula C4H6. The term ordinarily signifies the more important of the two, 1,3-butadiene, which is the major constituent of many synthetic rubbers. It was first manufactured in Germany during World War I from acetylene. During World War II, butenes from…