NBR (nitrile, acrylic nitrile-butadiene rubber, buna-N)

Nitrile is the most commonly used elastomer in terms of the manufacture of polymers, rubber, synthetic fibers etc. Nitrile rubber (NBR) is a synthetic rubber, obtained by copolymerization of acrylonitrile and butadiene. The content of acrylonitrile in nitrile sealing mixtures substantially varies (from 18% to 50%) and affects the physical properties of the finished material. The higher the content of acrylonitrile, the better the resistance to oils and fuel, however along with it the elasticity and resistance to shrinking will reduce. With a low content of acrylonitrile this rubber will possess very good low-temperature properties. In view of the conflicting facts, compromise is often the best solution, therefore a mean value of acrylonitrile is normally used.

In comparison to other elastomers, rubber NBR is distinctive for its great mechanical properties and high wear resistance. On the downside, the weaknesses of the nitrile are poor resistance to ozone and rapid aging if exposed to changing weather conditions and atmospheric effects. Other types of this rubber, called hydrogenated HNBR are more resistant to ozone and aging. A significantly improved version of the NBR is a carboxylated nitrile rubber (XNBR) which is used for industrial seals due to its great wear resistance.

Usage:

gaskets, membranes, hoses, products resistant to oil and low temperatures, general use in the industry.

Advantages:

• excellent wear resistance,
• resistant to petrol, mineral greases and oils.

Disadvantages:

• poor resistance to changing weather conditions
• medium heat resistance.

Temperature resistance: from – 30 °C to 110 °C.

Hardness: 30 to 95 Shore A.