HNBR vs. NBR - R.E. Purvis

When it comes to selecting the right material for seals, gaskets, and O-rings, two common choices in the rubber industry are Nitrile Butadiene Rubber (NBR) and Hydrogenated Nitrile Butadiene Rubber (HNBR). Both materials are renowned for their durability and versatility, but they offer distinct advantages depending on the application. This guide will help you understand the differences between HNBR and NBR and how to choose the right one for your needs.

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What is NBR?

Nitrile Butadiene Rubber (NBR), also known as Buna-N or simply nitrile, is a synthetic rubber copolymer made from acrylonitrile and butadiene. NBR is well-regarded for its excellent resistance to petroleum-based oils and fuels, making it a popular choice in automotive, aerospace, and industrial applications.

Key Characteristics of NBR:

• Oil and Fuel Resistance: Exceptional resistance to petroleum-based oils and fuels.
• Temperature Range: Typically ranges from -40°C to +120°C (-40°F to +248°F).
• Abrasion Resistance: Good wear and tear resistance.
• Cost-Effective: Generally more affordable than HNBR.

What is HNBR?

Hydrogenated Nitrile Butadiene Rubber (HNBR) is a derivative of NBR that has been hydrogenated to improve its physical and chemical properties. The hydrogenation process significantly enhances its resistance to heat, ozone, and various chemicals, making HNBR a superior choice for more demanding applications.

Key Characteristics of HNBR:

• Enhanced Temperature Range: Can withstand temperatures from -40°C to +150°C (-40°F to +302°F), and in some cases even higher.
• Chemical Resistance: Superior resistance to a broader range of chemicals, including ozone and oxidizing agents.
• Mechanical Properties: Improved tensile strength, elongation, and abrasion resistance compared to NBR.
• Longevity: Increased durability and lifespan in harsh environments.

Comparing NBR and HNBR

Temperature Resistance

• NBR: Suitable for applications with moderate temperature requirements.
• HNBR: Ideal for high-temperature applications, maintaining flexibility and performance in extreme conditions.

Chemical Resistance

• NBR: Good resistance to oils and fuels but less effective against ozone and oxidizing agents.
• HNBR: Excellent resistance to a wide range of chemicals, including ozone, making it suitable for outdoor and high-chemical exposure applications.

Mechanical Properties

• NBR: Offers good mechanical properties, including abrasion resistance.
• HNBR: Enhanced mechanical properties, providing better tensile strength and elongation.

Cost

• NBR: More cost-effective, making it a preferred choice for applications where high-performance characteristics are not critical.
• HNBR: Generally more expensive due to the additional hydrogenation process and improved performance benefits.

Application Longevity

• NBR: Adequate for many standard applications but may degrade faster in harsh conditions.
• HNBR: Longer lifespan in demanding environments, reducing the need for frequent replacements.

Choosing the Right Material

The choice between NBR and HNBR depends on the specific requirements of your application. Here are some factors to consider:

• Operating Temperature: If your application involves high temperatures, HNBR is the better choice.
• Chemical Exposure: For environments with exposure to ozone, oxidizing agents, or aggressive chemicals, HNBR offers superior resistance.
• Budget Constraints: NBR is a cost-effective option for applications with less demanding conditions.
• Mechanical Stress: For applications requiring high tensile strength and durability, HNBR's enhanced properties are advantageous.

Conclusion

Both NBR and HNBR are versatile and reliable materials with their unique strengths. Understanding the differences between these two types of rubber can help you make an informed decision, ensuring optimal performance and longevity for your seals, gaskets, and O-rings. Whether you choose NBR for its cost-effectiveness and oil resistance or HNBR for its superior temperature and chemical resistance, selecting the right material is crucial for the success and reliability of your application.

When looking for a high performance gasket, rubber seals often lack the ability to remain durable if an application comes in contact with oils. For these situations, consider using Nitrile Butadiene Rubber, also known as NBR, gaskets. Nitrile gasket material is one of the few rubbers that are particularly resistant to petroleum, mineral, and vegetable oils, as well as some acid solutions and water. These industrial rubber seals are commonly found in automotive, aeronautical, food service and sewer applications due to their specialized oil resistant properties.

Properties: Nitrile rubber is a synthetic rubber composed of a copolymer of butadiene and acrylonitrile. The amount of acrylonitrile determines the resistance and flexibility of the material. Most compositions will consist of 15 to 50 percent acrylonitrile. The increasing content of acrylonitrile lends higher strength, greater resistance to hydrocarbon oils, and lower permeability to gases to the compound, making these acrylonitrile-saturated compounds better suited for highly sensitive applications. The more acrylonitrile in the composition, however, also decreases the flexibility of the rubber because acrylonitrile possesses a higher glass transition temperature. This refers to the temperature below when molecules become stuck in a rigid, glassy state. This is due to the cross linking of molecular chains that occurs. When temperatures lower, segments cannot move as much. At a certain point, the molecule segments are completely frozen or stiff so that they cannot elongate without breaking. A hydrogenated version of NBR, also known as HNBR, is more resistant to low temperatures, remaining flexible, while also resisting thermal and oxidative deterioration. This is important because NBR is most susceptible to atmospheric molecules, such as ozone or ketone molecules.

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Nitrile – Commercial Grade Black – 60A

• Able to resist ozone, making it good for outdoor use
• Our nitrile rubber sheets have a smooth finish
• Can operate in temperatures between -20° F and 170° F
• Our NBR material is available in custom gauges of up to 2” thick and 72” long

Superior Oil Resistance: Buna-N sheet rubber is very popular for use in applications that see a regular presence of natural and synthetic oils and greases. In fact, nitrile rubber was first developed for this purpose in the years after World War I. Over the years, it has gained a reputation for being the go-to elastomer for any application that involves oils. Whereas other rubber materials can be damaged by oils and greases, nitrile exhibits a durable longevity when put into contact with such substances. As a result, NBR material is perfect for commercial, industrial, and automotive uses.

Flexible Rubber: Our Buna-N sheet has a durometer rating of 55-65. It is a medium grade rating that means the elastomer features more flexibility and elasticity than 70 durometer rubbers. It is not the hardest rubber around, but it does have decent resistance to abrasions. However, its flexibility allows it to be better used as seals, gaskets, and bumpers for a large number of different commercial and industrial applications.

More Properties: Of course, lower temperature is a relative term as NBR can actually handle a wide range of temperatures, making it ideal for aeronautical applications. NBR continues to work effectively in conditions that range from -40 degrees Celsius up to +108 degrees Celsius. NBR gaskets are so effective against chemicals that they are used in the nuclear industry. These industrial rubber seals provide good compressibility to create an air-tight vacuum or seal. This high performance gasket also features good abrasion resistance, durability, aging resistance, and low gas permeability. These qualities make NBR sealing popular in several industries where specific resistances must be upheld. NBR gaskets are not the cheapest material gaskets and their specialized abilities are often reserved for applications that require them rather than for extra precautionary uses.

While Nitrile Butadiene Rubber contains several cons, they are the most recommended industrial rubber seals for applications involving oils. These gaskets are meant for specific situations and are tailored to effectively create vacuum seals without wearing down or becoming ineffective. This high performance gasket is durable and is meant to withstand extreme situations of impact and heat. From aeronautical applications to food processing, nitrile gasket material is used for everyday and extraordinary situations where it is crucial for the nbr gaskets to remain durable.

Nitrile – Commercial Grade White – 60A

• Also available in black
• Excellent resistant to some oils and chemicals
• Can operate in temperatures between -20° F and 180° F
• Blend of nitrile, neoprene, and styrene butadiene rubbers
• Medium durometer (55-65) means that the nitrile material is flexible.

Oil-Resistant Rubber: Nitrile, or Buna-N rubber as it was originally known, was developed to be an oil-resistant alternative to natural rubber back in the years after World War I. Nitrile material is still used today whenever good oil and grease resistance is needed. White nitrile can resist organic and synthetic oils. While other types of elastomers can degrade when exposed to oils and greases, nitrile rubber can keep its form and integrity, making sure that it does its part to keep your application functioning.

Custom Fabrication: This white sheet rubber is available for custom specified fabrication. It comes in thickness gauges from 1/16” all the way up to 2”. You can also specify to us the specific length (up to 50ft depending on thickness) and width (up to 78”) you require from your oil-resistant rubber sheet. A customized sheet of white nitrile is great for general gasketing and sealing applications.

Contact us to discuss your requirements of NBR Rubber OIL SEAL. Our experienced sales team can help you identify the options that best suit your needs.