Hydrogenated Nitrile Rubber, HNBR

Patented by Bayer in 1975 and first introduced to the market in 1986 under the name Therban.

This is a saturated version of NBR with much greater temperature resistance. With ACN contents of 18 – 49% and a degree of saturation of 80 to 99%. Temperature resistance options from -45 deg C to above 165 deg C, with peaks up to 180 deg C.

This is a mechanically robust elastomer with good compression set, good "hot tear" and good ozone resistance. HNBR is highly resistant, showing resistance to mineral oils, including unrefined oils containing amines, sulphur, nitrogen oxides, and is also resistant to high-energy ionising radiation.

Also shows good resistance to hot water and steam. You could say that HNBR fills the gap between NBR and FKM. HNBR remains resistant to aggressive media at higher temperatures.

The major advantages of the considerably more expensive HNBR over NBR are the greater temperature resistance (sustained +150 C, with higher peaks), ozone resistance and the better mechanical properties. However, HNBR shows poor resistance to certain oxygenated solvents and aromatic hydrocarbons.

Not resistant to chlorinated hydrocarbons, polar solvents (ketones, ethers and esters) and strong acids.