Nitrile rubber

Nitrile rubber, also known as NBR, Buna-N, and acrylonitrile butadiene rubber, is a synthetic rubber derived from acrylonitrile (ACN) and butadiene. This type of rubber is resistant to oil, fuel, and other chemicals, making it a valuable material in the automotive and aeronautical industry for the production of fuel hoses, gaskets, and seals. Its resistance to a wide range of temperatures and its ability to maintain flexibility over long periods of time also make it suitable for various industrial applications.

Properties

Nitrile rubber is known for its excellent resistance to petroleum-based oils and fuels, silicone greases, hydraulic fluids, water, and alcohols. It has a temperature range of -40 to 108°C (-40 to 226°F), which can be extended through special formulations. The acrylonitrile content in NBR ranges from 18% to 50%, with higher acrylonitrile content providing better resistance to oils and fuels, while lower content yields better flexibility at low temperatures.

Applications

Due to its robust properties, NBR is used in a variety of applications. In the automotive industry, it is used for fuel and oil handling hoses, seals, grommets, and self-sealing fuel tanks. The aeronautical industry utilizes NBR for fuel and hydraulic hoses and seals. It is also used in the manufacturing of disposable non-latex gloves, within the nuclear industry for sealing and protection, and in the oil and gas industry for packers, seals, and blowout preventers.

Production

Nitrile rubber is produced through a process called emulsion polymerization of acrylonitrile and butadiene. The properties of NBR can be adjusted by varying the acrylonitrile content, which influences the rubber's resistance to oils, fuels, and other chemicals, as well as its temperature resistance.

Environmental and Health Aspects

While NBR is resistant to many chemicals, it can degrade when exposed to ozone, strong acids, and alkalis. It is also not suitable for applications involving ketones, esters, ethers, aldehydes, and nitro hydrocarbons. The production and disposal of nitrile rubber must be managed carefully to avoid environmental contamination. Workers involved in the manufacturing process of NBR should also be protected from exposure to monomers and other potentially hazardous chemicals used in its production.

Alternatives

Alternatives to nitrile rubber include fluoroelastomers (FKM), which offer higher resistance to heat and chemicals but at a higher cost, and silicone rubber, which provides better temperature resistance but lower tensile strength. The choice between NBR and its alternatives depends on the specific requirements of the application, including resistance to chemicals, temperature, and cost considerations.

See Also

• Elastomer
• Polymer
• Rubber
• Synthetic rubber