When looking for a high performance gasket, rubber seals often lack the ability to remain durable if an application comes in contact with oils. For these situations, consider using Nitrile Butadiene Rubber, also known as NBR, gaskets. Nitrile gasket material is one of the few rubbers that are particularly resistant to petroleum, mineral, and vegetable oils, as well as some acid solutions and water. These industrial rubber seals are commonly found in automotive, aeronautical, food service and sewer applications due to their specialized oil resistant properties.
History: Nitrile Butadiene rubber is the result of research done between the two world wars. Patented by German chemists, Erich Konrad and Eduard Tschunkur, NBR was first acknowledged in 1934. The United States began to produce this synthetic rubber during World War II, which led to the popularity of the elastomer in American industries (http://www.britannica.com/EBchecked/topic/416122/nitrile-rubber-NBR).
Properties: Nitrile rubber is a synthetic rubber composed of a copolymer of butadiene and acrylonitrile. The amount of acrylonitrile determines the resistance and flexibility of the material. Most compositions will consist of 15 to 50 percent acrylonitrile. The increasing content of acrylonitrile lends higher strength, greater resistance to hydrocarbon oils, and lower permeability to gases to the compound, making these acrylonitrile-saturated compounds better suited for highly sensitive applications. The more acrylonitrile in the composition, however, also decreases the flexibility of the rubber because acrylonitrile possesses a higher glass transition temperature. This refers to the temperature below when molecules become stuck in a rigid, glassy state. This is due to the cross linking of molecular chains that occurs. When temperatures lower, segments cannot move as much. At a certain point, the molecule segments are completely frozen or stiff so that they cannot elongate without breaking. A hydrogenated version of NBR, also known as HNBR, is more resistant to low temperatures, remaining flexible, while also resisting thermal and oxidative deterioration. This is important because NBR is most susceptible to atmospheric molecules, such as ozone or ketone molecules.
General Uses: Many medical professions use NBR sealing to keep their expensive and acutely sensitive equipment tools safe and untainted by common outdoor molecules. Like many rubbers, however, nitrile gasket material becomes less flexible at lower temperatures as the molecules become locked in the glassy state mentioned before.
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More Properties: Of course, lower temperature is a relative term as NBR can actually handle a wide range of temperatures, making it ideal for aeronautical applications. NBR continues to work effectively in conditions that range from -40 degrees Celsius up to +108 degrees Celsius. NBR gaskets are so effective against chemicals that they are used in the nuclear industry. These industrial rubber seals provide good compressibility to create an air-tight vacuum or seal. This high performance gasket also features good abrasion resistance, durability, aging resistance, and low gas permeability. These qualities make NBR sealing popular in several industries where specific resistances must be upheld. NBR gaskets are not the cheapest material gaskets and their specialized abilities are often reserved for applications that require them rather than for extra precautionary uses.
While Nitrile Butadiene Rubber contains several cons, they are the most recommended industrial rubber seals for applications involving oils. These gaskets are meant for specific situations and are tailored to effectively create vacuum seals without wearing down or becoming ineffective. This high performance gasket is durable and is meant to withstand extreme situations of impact and heat. From aeronautical applications to food processing, nitrile gasket material is used for everyday and extraordinary situations where it is crucial for the nbr gaskets to remain durable.