by Paul M. Smith, Zeon
Hydrogenated acrylonitrile butadiene rubber (HNBR) is a thermoset elastomer derived from monomers of acrylonitrile and
butadiene. What separates HNBR from acrylonitrile butadiene rubber (NBR) is a hydrogenation process that reacts the butadiene
segments of NBR with hydrogen to produce ethylene. These ethylene segments provide HNBR with higher mechanical properties, as well as greater temperature and chemical resistance compared to NBR.
HNBR is rated for continuous use at temperatures from125°C to 150°C, depending on several compounding factors, with the choice of cure system being one of the most critical. While a sulfur cure can provide flex fatigue and high tensile properties, it does not have high temperature stability. Peroxide cured HNBR is the only suitable cure system for long term, 150°C temperature resistance. Peroxide cured HNBR also provides high modulus and low compression set, making it an ideal material for sealing applications. HNBR is the sealing material of choice in many automotive and oil well applications where high mechanical strength is needed, in addition to high temperature and chemical resistance.