Hydrogenated Nitrile Rubber (HNBR)
Hydrogenated Nitrile (HNBR) o-rings, also known as Highly Saturated Nitrile (HSN), are made of a synthetic polymer that is obtained by saturating the double bonds in nitrile=s butadiene segments with hydrogen. This special hydrogenation process reduces many double bonds in main chains of NBR polymers. This process results in the superior heat, ozone, chemical resistance and mechanical characteristics of HNBR over standard Nitrile. HNBR o-rings are available in 70 durometer, 80 durometer, and 90 durometer.
Just like NBR, there are different levels of Acrylonitrile (ACN) content in different HNBR polymers. The ACN content can be varied from 17% to 49%. Lower ACN content gives better low-temperature properties but lesser resistance to fuels and polar lubricants. Higher ACN content gives inferior low-temperature properties but improves fuels and polar lubricants resistance. Standard HNBRs typically have 36% ACN content.
Cure System, Peroxide-Cured:
HNBR o-rings are usually peroxide-cured but can also be sulfur-cured to improve flexible properties in dynamic systems. However, sulfur-curing will reduce the heat resistance and cause an inferior compression set.
Standard Low Temp: -40°C (-40°F)
Standard High Temp: 150°C (302°F)