A Comprehensive Guide to Nitrile Butadiene Seals

Nitrile Butadiene Seals (NBR) seals are synthetic elastomers that are composed of acrylonitrile and butadiene. The working properties of NBR seals may vary depending on the ratio of acrylonitrile and butadiene. For instance, if the acrylonitrile content is lower, the glass transition temperature will also be less. On the other hand, if the acrylonitrile content is high, the seal will exhibit excellent nonpolar solvent resistance. NBR elastomers are widely preferred across various industries due to their affordable cost and desirable working properties.

A Brief Overview about the Mechanical Properties of NBR

NBR gaskets, O-rings, and different sealing devices can provide multiple beneficial properties. It has a functional temperature range of -50° C to + 100° C (+ 120° C). It exhibits a mechanical hardness of 30-90 Shore A.

Some salient features include:

• Oil resistant
• Water & alcohol resistant
• Weather-resistant & low aging
• Abrasion-resistant
• Low compression set
• Silicone greases & hydraulic fluid resistant
• High mechanical strength

What are the Common Applications of NBR?

NBR is preferred in various applications such as aerospace, consumer, medical, military, automobile, and marine. Among these industries, NBR is used in applications like:

• Oil seals
• Disposable non-latex gloves
• Off-road equipment
• Automobile transmission belts
• Belts, hoses, O rings, gaskets
• Floor mats & footwear
• Static & dynamic hydraulic seals
• Automotive, marine & aircraft fuel systems

Speaking of disposable gloves, NBR offers more resistance to oil and acids when compared to natural rubber. However, you can expect better flexibility from natural rubber. NBR products are more resistant to degradation and punctures when they are exposed to specific chemicals. This makes them an excellent choice for many applications.

What are the Limitations of NBR?

As you can see, NBR can offer excellent sealing. However, there are few limitations you must be aware of. For instance, NBR can be compromised by ozone, thereby reducing compatibility with sunlight exposure for long periods. NBR is also sometimes compounded with plasticizers which can cause issues with certain types of plastics as it can migrate out of rubber compounds. Next, ensure that the right levels of each compound are present in your product. The reason being, to cheapen the product, few commercial nitriles in the market are mixed with SBR.

If you are interested to know more about NBR seals, then feel free to connect with Harkesh Rubber. We can help you select and design the appropriate rubber material for your gasket, o-ring, or seal applications.