What is the Difference Between NBR and HNBR?

The main difference between Nitrile Butadiene Rubber (NBR) and Hydrogenated Nitrile Butadiene Rubber (HNBR) lies in their chemical structure and properties. NBR is a non-hydrogenated form, while HNBR is a hydrogenated form of nitrile rubber. Here are some key differences between NBR and HNBR:

1. Chemical Structure: NBR contains a carbon-carbon double bond, which is not present in HNBR due to the hydrogenation process. This modification gives HNBR improved temperature stability and better resistance to atmospheric ozone and weathering.
2. Temperature Range: HNBR has a higher maximum temperature for mechanical properties compared to NBR, with a maximum temperature of 190°C (374°F) versus 110°C (230°F).
3. Ozone Resistance: HNBR materials have slightly improved ozone resistance compared to NBR.
4. Cost: HNBR compounds are more expensive than NBR compounds but can offer significant advantages in some applications, such as fluid resistance and temperature performance.

Both NBR and HNBR are widely used in sealing applications and other products like belts, rollers, and hoses. They are known for their resistance to mineral and vegetable-based oils, greases, and cold-to-warm water. However, they should not be used with aromatic fuels or hydrocarbons, polar solvents like ketones and acetone, or in situations where ozone and weathering resistance is required.

Comparative Table: NBR vs HNBR

The main difference between NBR and HNBR is that NBR is a non-hydrogenated form of nitrile rubber, while HNBR is a hydrogenated form of nitrile rubber. Here is a comparison table highlighting the differences between NBR and HNBR:

HNBR is widely used due to its physical strength, oil and chemical resistance, and minimal environmental impact. The type of HNBR used varies depending on the application, with low ACN grades suitable for low-temperature applications and high ACN grades suitable for high-temperature applications.