Nitrile's chemical composition, a copolymer of butadiene and acrylonitrile, is responsible for its outstanding oil resistance. The degree of resistance to oil and fuel increases with the acrylonitrile (ACN) content, though a higher ACN content often results in a slight reduction in low-temperature flexibility. This allows manufacturers to tailor the compound for specific application needs, such as better low-temperature performance in cold climates or superior oil swell resistance in engine systems.


Despite their numerous strengths, a key limitation of standard Nitrile seals is their poor resistance to ozone, sunlight (UV), and weathering. Therefore, NBR is generally not recommended for applications involving prolonged outdoor exposure or contact with harsh, polar solvents (like ketones, esters, and chlorinated hydrocarbons). Nonetheless, their combination of low cost, excellent oil resistance, and good mechanical properties makes them the primary sealing choice for automotive engine parts, hydraulic and pneumatic systems, and general industrial machinery where extreme temperatures or aggressive chemicals are not present.