Nitrile rubber

NBR is the most common standard material for O-rings because of its good mechanical properties and resistance to mineral oil-based lubricants and greases. These properties are usually determined by the acrylonitrile content (ACN between 18% and 50%). A low ACN content ensures good flexibility at low temperatures, but offers limited resistance to oils and fuels; as the ACN content increases, the low temperature flexibility reduces and the resistance to oils and fuels improves.