Hydrogenated Nitrile Rubber ( HNBR)
Hydrogenated Nitrile(HNBR) is a synthetic polymer that is obtained by saturating the double bonds in nitrile’s butadiene segments with hydrogen, and it is also called HSN(Highly Saturated Nitrile). This special hydrogenation process reduces lots of double bonds in main chains of NBR polymer, thus HNBR possesses superior heat, ozone, chemical resistance and mechanical characteristics over standard Nitrile.
Same as 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 poorer fuels and polar lubricants. Higher ACN content gives poorer low temperature properties but improves fuels and polar lubricants resistance. Standard HNBRs typically have 36% ACN content.
Cure system - Peroxide-Cured
HNBRs are usually Peroxide-cured for standard compounds of Ge Mao. It also can be Sulfur-cured to improve flexible properties in dynamic system but will reduce the heat resistance and cause poorer compression set.
Other Common Variations
• HNBRs are often internally lubricated to improve ease of installation or reduce friction for dynamic applications.
• HNBRs can be formulated with only “white list” ingredients as specified in 21.CFR 177.2600 for use in applications where the elastomer will be in contact with food or beverages.
• HNBRs are usually used in automotive air conditioning system where R134a refrigerant gas or new refrigerant for environment protection like R401a, R404a, R410a, R507 and R744 is used.
• HNBRs are also used in automotive shaft system because of their excellent abrasion resistance.
• In deeper oil wells, it requires material resistance to heat, crude oil, hydrogen sulfide, steam and explosive decompression…etc. Special compounds of HNBR can be available for this application.
ASTM D 1418 Designation: HNBR
ISO/DIN 1629 Designation: HNBR or NBM
ASTM D2000 / SAE J 200 Codes: CH, DF, DH
Standard Color(s): Black, Green
Hardness Range: 50 to 90 Shore A
Relative Cost: High
Standard Low Temperature: -40°C / -40°F
Standard High Temperature: 150°C / 302°F
Special Compound Low Temperature: -55C / -67°F
Special Compound High Temperature: 165°C / 330°F
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