NBR – Nitrile Rubber
NBR is the abbreviation for nitrile butadiene rubber. This is a synthetic rubber that was developed during the 1930s. It is fabricated through the co-polymerization of acrylonitrile (ACN) (polar building block) and 1.3-butadine (nonpolar building block). Its attributes mainly depend on its ACN content.
The manufacturer can vary the content and thus produce different types of the material. In the process, the ACN content determines the balance between media resistance and low-temperature flexibility. Low ACN content produces a low glass transition temperature but also leads to greater swelling in oils and fats. As the ACN content increases, this behavior reverses direction – due to the polar components in the polymer.
NBR is stable in petroleum oils and greases, in vegetable and animal oils and fats, in hydraulic fluids (HFA¹, HFB² and HFC³), in aliphatic hydrocarbons (propane, butane, gasoline, diesel fuel). NBR displays low media resistance in polar media such as solvents (acetone, MEK, ethyl acetate, diethyl ether), glycol-based brake fluid, superheated steam, HFD pressure fluids, ultraviolet light, and ozone.
Nitrile rubber exhibits superior mechanical strength with high elasticity as well as good deformation behavior in a temperature range between -30 °C and 100 °C. Its relatively low heat resistance can be traced to the presence of reactive double bonds. It is used for oil- and fuel-resistant seals such as Simmerrings®, O-rings and frame seals. The use of NBR marked the arrival of elastomers as a sealing material particularly in general industry. It is also employed in the auto industry.
¹ Oil and water emulsions or solvents with a water content of more than 80 percent and concentrate based on petroleum oils or soluble polyglycols.
² Water-in-oil emulsions with water content of more than 40 percent and petroleum oil.
³ Water glycol with a water content of more than 35 percent and polyglycol solution.
Sealing solutions specially developed for the process industry in accordance with hygienic design and materials with industry-specific approvals.