HNBR vs. NBR

Attribute	HNBR	NBR
Chemical Name	Hydrogenated Nitrile Butadiene Rubber	Nitrile Butadiene Rubber
Temperature Range	−40°C to +150°C	−40°C to +120°C
Hardness Range	60 to 90 Shore A	40 to 90 Shore A
Tensile Strength	15 to 30 MPa	10 to 25 MPa
Elongation at Break	200% to 600%	200% to 600%
Resistance to Ozone	Excellent	Good
Resistance to Oil	Excellent	Excellent
Resistance to Fuel	Good	Good
Resistance to Chemicals	Good	Good

Introduction

When it comes to choosing the right elastomer for various applications, engineers and manufacturers often consider different factors such as temperature resistance, chemical compatibility, and mechanical properties. Two commonly used elastomers in various industries are Hydrogenated Nitrile Butadiene Rubber (HNBR) and Nitrile Butadiene Rubber (NBR). While both materials share some similarities, they also have distinct attributes that make them suitable for specific applications. In this article, we will explore and compare the attributes of HNBR and NBR to help you make an informed decision for your specific needs.

Chemical Composition

HNBR and NBR are both synthetic elastomers derived from nitrile rubber. However, the key difference lies in their chemical composition. NBR is a copolymer of butadiene and acrylonitrile, while HNBR is a modified version of NBR with additional hydrogen atoms added to the polymer chain. This hydrogenation process enhances the material's resistance to heat, ozone, and chemicals, making HNBR more suitable for demanding applications where NBR may not perform as effectively.

Temperature Resistance

When it comes to temperature resistance, HNBR outperforms NBR due to its hydrogenation process. HNBR can withstand higher temperatures, typically ranging from -40°C to 150°C (-40°F to 302°F), while NBR has a lower temperature range of -30°C to 100°C (-22°F to 212°F). This increased temperature resistance makes HNBR a preferred choice for applications exposed to extreme heat or fluctuating temperature conditions.

Chemical Compatibility

Both HNBR and NBR exhibit excellent resistance to oils, fuels, and hydraulic fluids, making them widely used in automotive and industrial applications. However, HNBR offers superior chemical resistance compared to NBR. The hydrogenation process in HNBR reduces the polymer's susceptibility to degradation caused by exposure to chemicals, acids, and bases. This enhanced chemical compatibility makes HNBR a suitable choice for applications where NBR may not provide adequate resistance.

Mechanical Properties

When it comes to mechanical properties, both HNBR and NBR offer excellent tensile strength, tear resistance, and abrasion resistance. However, HNBR generally exhibits better mechanical properties compared to NBR. The hydrogenation process in HNBR improves its overall strength, durability, and resistance to wear and tear. This makes HNBR a preferred choice for applications that require high-performance elastomers subjected to heavy loads, dynamic movements, or harsh operating conditions.

Sealing Applications

Both HNBR and NBR are widely used in sealing applications due to their excellent sealing properties. However, the choice between the two depends on the specific requirements of the application. NBR is commonly used for general-purpose sealing applications, such as gaskets, O-rings, and seals in automotive engines, hydraulic systems, and water applications. On the other hand, HNBR is preferred for more demanding sealing applications, especially in industries such as oil and gas, chemical processing, and aerospace, where exposure to extreme temperatures, chemicals, and high-pressure environments is common.

Cost Considerations

Cost is an important factor to consider when selecting an elastomer for a particular application. In general, NBR is more cost-effective compared to HNBR. The additional hydrogenation process involved in producing HNBR increases its manufacturing cost, making it relatively more expensive than NBR. However, it is essential to evaluate the specific requirements of your application and determine whether the enhanced attributes of HNBR justify the higher cost or if NBR is sufficient for your needs while offering cost savings.

Conclusion

In summary, HNBR and NBR are both versatile elastomers with their own unique attributes. While NBR is a cost-effective option suitable for general-purpose sealing applications, HNBR offers enhanced temperature resistance, chemical compatibility, and mechanical properties, making it ideal for demanding applications in industries such as automotive, oil and gas, and chemical processing. By understanding the differences between HNBR and NBR, you can make an informed decision and select the most suitable elastomer for your specific application, ensuring optimal performance and longevity.