Hydrogenated nitrile HNBR:
Composing:
This is a relatively new elastomer, making its first appearance in 1984. The symbol for the generic material is HNBR standing for highly saturated nitrile.

Properties and Applications:
It has all the attributes of NBR plus a very much higher heat resistance, dependent on the grade chosen. It also has very good weather and abrasion resistance, plus good mechanical strength. It is used in oilfields where it has resistance to amine corrosion inhibitors and better hydrogen sulfide resistance than NBR. It has established itself in automotive applications for timing belts, gaskets and O-rings, where higher temperature resistant elastomers are needed. Peroxide cured HNBR has heat aging resistance up to 150℃, based on around 1000 hours, while sulfur donor cured HNBR temperature resistance might drop to 135℃. Cost is somewhat less than conventional fluorocarbon rubber (FKM) on a weight basis, also since the density (using g/cm3, which approximates to specific gravity) of HNBR is about half that of FKM, more products can be made for the same weight purchased.