Nitrile rubber—also referred to as NBR, Buna-N, or NBR Acrylonitrile Butadiene Rubber—is a synthetic rubber made from acrylonitrile (ACN) and butadiene. It is best known for its strong resistance to oils, fuels, and many chemicals, which makes it one of the most widely used sealing and gasketing materials today.
Buna-N Rubber was first patented in Germany in 1934 as part of a project to create synthetic rubbers resistant to oil and fuel. In the U.S., it was labeled GR-N (Government Rubber – Nitrile) and eventually became widely known as Nitrile Rubber or simply NBR.
Despite its high performance, this rubber material remains surprisingly cost-effective. These factors have effectively established Buna-N Rubber as a popular choice, particularly for power, oil and gas applications.
Advantages of Nitrile Rubber
Nitrile Rubber (Buna Nitrile) is often chosen for applications needing:
- Excellent oil and gasoline resistance
- Strong resistance to petroleum-based hydraulic fluids
- Good resistance to many alkalis and acids
- Ability to be produced in vibrant colors
Disadvantages of Nitrile Rubber
While Buna-N is extremely versatile, it does have some limits.
- Poor flame resistance
- Poor long-term outdoor durability (ozone and UV resistance)
Key Properties of NBR Rubber
When deciding if Nitrile Rubber is right for your project, the following properties are useful starting points. Always consult a material specialist for the best fit.
Nitrile (NBR)’s General Physical Properties
| Property | Value |
|---|---|
| Hardness (Shore A) | 35 to 90 |
| Tensile Strength (psi) | 200 to 3500 |
| Elongation at Break (%) | 400 to 600 |
| Compression Set (%) | 20 to 50 |
| Temperature Range (°F) | -40 to 250 |
Nitrile (NBR)’s General Chemical Resistances
| Chemical | Resistance Rating |
|---|---|
| Mineral Oils and Greases | Excellent |
| Fuels | Outstanding |
| Hydraulic Fluids | Outstanding |
| Alcohols | Good |
Nitrile (NBR)’s General Characteristics
| Characteristic | Characteristic Rating |
|---|---|
| Abrasion Resistance | Excellent |
| Oil Resistance | |
| Impact Resistance | Outstanding |
| Rebound Rating | |
| Tear Resistance | |
| Flex Cracking Resistance | |
| Chemical Resistance | |
| Oxidation Resistance | |
| Low Temperature Resistance | |
| Gas Permeability | |
| Radiation Resistance | |
| Maximum Service Temperatures | Fair |
| Weather Resistance | Poor |
| Ozone Resistance | |
| Flame Resistance |
While these values represent Buna Nitrile’s general performance, with the right compounding partner, the material can be optimized for your specific application.
Standard Applications of Nitrile Rubber
Due to its balance of performance and cost, Nitrile Rubber is the industry standard for many applications. Examples include:
- Oil Field Seals: Buna Nitrile offers long-lasting durability and fuel resistance in demanding oil and gas applications.
- Electrical Transformer Gaskets: Formulations of Buna-N resist transformer oils and reduce static buildup.
- Food Processing Equipment: Nitrile o-rings and gaskets withstand oils, fats, and greases while handling a wide temperature range.
- Automotive Valves and Hoses: NBR Rubber works well in fuel systems, hydraulic hoses, and sealing components.
From Buna-N Rubber gaskets to custom NBR O-rings, this material remains a reliable choice wherever fuel and oil resistance are essential.
WARCO Advantage
Unlike many manufacturers that outsource compounding and mixing, WARCO offers complete vertical integration. Our team develops compounds, mixes materials, and manufactures Sheet Rubber, Molded Rubber, and Rubber Extrusions to your exacting specifications.
With over 7,000 developed compounds and deep technical expertise, WARCO can deliver standard or fully customized Nitrile Rubber solutions. All products are proudly made in the USA.
Takeaways
Nitrile rubber combines oil resistance, mechanical strength, and affordability in a way that few other rubber polymers can match. Its balance of performance and cost explains why Buna-N Rubber remains so popular across industries worldwide.
If you have any questions, email your questions to sales@warco.com, or contact us directly at (714) 532-3355.
