Hydrogenated acrylonitrile butadiene rubber (HNBR) is a unique elastomer, which is made from hydrogenating acrylonitrile butadiene rubber. It is produced from conventional nitrile rubber by hydrogenation of the unsaturated bonds in the butadiene units of the polymer, which can meet higher temperatures and retain better resistance and has become widely known for its physical strength. In reaction NBR polymers are filled with double and triple bonds in the polymer chain, which the bonds are broken and replaced with hydrogen, and form a higher performance material. As a result HNBR results in higher oil resistance, heat and strength, and better ozone resistance—all due to its polymer structure.
Hydrogenated nitrile butadiene rubber (HNBR) is also known as highly saturated nitrile (HSN). It has physical strength and retention of its properties after long-term exposure to heat, oil and chemicals. Compared to NBR, HNBR has its unique properties and higher temperature rating. And it offers an excellent range of performance at a cost between nitrile rubber (NBR) and silicone rubber (SI). HNBR fill the gap between these two elastomers in many areas of application where resistance to heat and aggressive media are required simultaneously. HNBR is an excellent choice for applications such as mining machinery and heavy tracks etc.
HNBR is produced from acrylonitrile-butadiene rubber, a copolymer of acrylonitrile (ACN) and 1,3-butadiene. Catalytic hydrogenation improves the chemical and thermal resistance of NBR, due to its double bonds of the butadiene monomer units remain in the NBR main chain. HNBR is susceptible to chemical influences, thermal degradation and oxidation. Unlike NBR, hydrogenated NBR elastomer has high heat, ageing resistance, and resistant to oils, flame-resistant hydraulic fluids, and some refrigerants. In long-term operation, fully hydrogenated HNBR grades can withstand temperatures of up to 150°C.
HNBR’s acrylonitrile content in the vulcanisates determine the oil resistance. HNBR also offers outstanding physical properties, such as abrasion resistance, combined with great mechanical properties even at raised temperature, and excellent resistance to many chemically aggressive oils. Due to HNBR is acquired through the saturation of nitrile with hydrogen on its hydrocarbon chains, the hydrogenation of the polymeric chain results in improved strength, hot air, and steam resistance and a very good low-temperature flexibility.
Standard colour: black
Good chemical resistance
High mechanical and dynamic strength
Ozone and weathering resistance
Good low-temperature flexibility
Low compression set even at high temperature
High ageing resistance
Thermal stability from -40 to +150°C
Good tensile and tear strength
High abrasion resistance
Excellent resistance to lubricants with
Very good hot air and steam Resistance.
Low permeability to volatiles and gases
Excellent heat and oxidation stability
Improved wear resistance
Excellent pressure resistant
Excellent tear resistant
High manufacturing cost
Less than 0.5% reaction with oil
The acrylonitrile content and the degree of hydrogenation of the butadiene copolymer determine the properties of hydrogenated nitrile rubber. Compared with NBR, HNBR has better oil and chemical resistance and can withstand much higher temperatures. As NBR is a non-hydrogenated form, whereas HNBR is a hydrogenated form. HNBR or hydrogenated nitrile rubber is a synthetic copolymer of acrylonitrile and butadiene and also known as highly saturated nitrile, which considering the chemical composition of the polymer material. HNBR used widely due to its favourable properties such as high strength, retention of properties upon exposure to heat, oil, and chemicals. Moreover, HNBR has a comparatively high tensile strength compared to NBR. HNBR has great resistance to sour oil and gas, ozone, hot water and steam. Compounds exhibit good dynamic behaviour at elevated temperatures, as a result, physical properties such as tensile, tear, strength, elongation, abrasion resistance and compression set are excellent in HNBR.
HNBR also has some limitations, such as higher cost and limited resistance to aromatic oils, polar organic solvents, poor flame resistance, and it can easily be damaged by aromatic oils and polar organic.