Nitrile Buna-N (NBR) Material Guide

What is Nitrile Rubber?

Nitrile rubber, often referred to as Buna-N or NBR, is the general term for acrylonitrile-butadiene copolymer. It is one of the most widely used and cost-effective elastomers in sealing and gasketing applications.

Its popularity comes from a strong balance of chemical resistance, mechanical durability, and formulation flexibility, which makes it a standard choice across automotive, aerospace, marine, oil and gas, hydraulic, and general industrial sectors.

Key Material Properties

NBR is widely specified because its properties can be tuned through formulation while still delivering reliable core performance:

• Oil, fuel, and chemical resistance — NBR performs exceptionally well with petroleum-based oils, hydrocarbon fuels, hydraulic fluids, silicone greases, water, and alcohols.
• Mechanical robustness — it offers a good balance of tensile strength, tear resistance, abrasion resistance, and overall durability.
• Strong sealing performance — with good compression set behaviour and flexibility, NBR is suitable for both dynamic and static seals, gaskets, O-rings, and hoses.
• Tailorable properties — varying the acrylonitrile content and compounding method can improve oil resistance, abrasion resistance, or low-temperature flexibility.
• Broad hardness and operating range — typical hardness spans roughly 40 to 90 Shore A, supporting everything from soft sealing elements to more rigid gasket compounds.
• Performance linked to ACN content — higher acrylonitrile content generally improves strength and oil resistance while lowering gas permeability.

Typical Applications

NBR appears in a broad range of industries and products, including:

• Seals, O-rings, gaskets, and hose systems in automotive, marine, and aircraft fuel or oil systems when approved compounds are used.
• Hydraulic systems, pumps, valves, and hose assemblies because of its resistance to hydraulic fluids and lubricants.
• Industrial sealing, floor mats, vibration dampers, general rubber parts, hoses, and mechanical gaskets where abrasion resistance and durability matter.
• Food-processing and pharmaceutical-safe seals when formulated to the required regulatory standards, including FDA-compliant grades.
• Low-temperature, off-road, and military applications when low-ACN or specialist low-temperature compounds are selected.

When to Choose Nitrile / Buna-N

Choose NBR when you need a durable, cost-effective, oil- and fuel-resistant elastomer for seals, gaskets, O-rings, hoses, and general sealing elements, especially in hydraulic, automotive, fuel, and standard industrial equipment.

Food-grade formulations are available where sanitary or food-contact requirements apply. For low-temperature duties or applications demanding improved abrasion resistance, low-temperature or higher-ACN variants can offer better performance.

If the application involves strong ozone exposure, UV or sunlight, aggressive solvents, ketones, acids, or sustained high temperatures, alternative elastomers may be more suitable.

Selection Considerations

Nitrile remains a workhorse material, but formulation details matter:

• Ozone sensitivity — NBR compounds can be attacked even by relatively small amounts of ozone, which limits outdoor durability unless specifically protected.
• Plasticiser migration — phthalate-type plasticisers used in some compounds can migrate and create compatibility issues with certain plastics.
• Regulatory changes — restrictions on some phthalates have limited their use, so compound choice should reflect current compliance requirements.

Looking for an alternative style? Contact our Sales team.

Compliance & Quality Considerations

Eastern Seals (UK) Ltd sources NBR compounds from approved manufacturers, and actual performance can vary according to ACN content, hardness, filler system, cure chemistry, and supplier-specific formulation.

The information on this page should be used as a general selection guide only. Always verify operating media, temperature range, regulatory requirements, and actual compound performance before final approval for service.