If you’ve ever worked with industrial seals, protective gloves, or automotive components, there’s a good chance you’ve encountered nitrile rubber. It’s one of the most widely used synthetic rubbers in the world, and for good reason. But what exactly is nitrile rubber, and why does it appear in so many demanding applications? This guide covers everything you need to know.
What is Nitrile Rubber?
Nitrile rubber, formally known as Nitrile Butadiene Rubber (NBR), is a synthetic elastomer produced by the copolymerisation of acrylonitrile (ACN) and butadiene. It is also commonly referred to as Buna-N or Perbunan, names that stem from its early commercial production history.
What sets nitrile rubber apart from natural rubber and other synthetic alternatives is its exceptional resistance to oils, fuels, and a wide range of industrial chemicals. This makes it the go-to material in environments where contact with petroleum-based substances is unavoidable.
Demand for nitrile rubber continues to grow, driven primarily by expansion in the automotive, oil and gas, and healthcare sectors.
How Nitrile Rubber is made
NBR is produced through the emulsion polymerisation of acrylonitrile (ACN) and butadiene. The ratio of these two monomers is one of the most important variables in determining the material’s final properties:
- Higher ACN content = greater resistance to oils and non-polar hydrocarbons, but reduced low-temperature flexibility.
- Lower ACT content = improved flexibility at cold temperatures, but reduced chemical resistance.
Most general-purpose applications use an ACN content of around 33%, which strikes the right balance between oil resistance and low-temperature performance. The polarity introduced by the nitrile groups (-CN) is what drives the material’s resistance to hydrocarbons such as mineral oils, diesels, and lubricants.
Key properties of Nitrile Rubber
NBR offers a well-rounded combination of physical and chemical properties that make it suitable across a broad range of industrial applications.
Oil and fuel resistance
Nitrile rubber offers significantly lower swelling in hydrocarbon oils compared to natural rubber or styrene-butadiene rubber (SBR). It resists degradation from petroleum-based oils, diesel, petrol, lubricants, and hydraulic fluids, making it the default choice for sealing applications in contact with these substances.
Temperature range
NBR performs reliably across a moderate temperature range of approximately –40°C to 120°C. Specially formulated compounds can extend this range, with some grades handling temperatures down to –54°C or up to 135°C for short-term exposure. This makes it suitable for most standard industrial and automotive environments, though it falls short of high-temperature specialists like silicone or Viton (FKM).
Tensile strength and abrasion resistance
When reinforced with carbon black, NBR compounds are well suited to dynamic and high-stress applications. The material also offers good resistance to abrasion, tearing, and compression; seals manufactured from nitrile maintain their shape and sealing integrity even after prolonged compression.
Chemical resistance
Beyond oils and fuels, NBR exhibits good resistance to alcohols, mild acids, water and glycol-based fluids, greases, and many organic compounds. It can also be blended with PVC to create hybrid compounds that improve oil resistance.
Water resistance
In solid or closed-cell sponges, nitrile rubber can withstand short-term exposure to water and is suitable for applications where moisture contact is a concern, though it is not recommended for prolonged immersion.
| Advantages of Nitrile Rubber | Disadvantages of Nitrile Rubber |
| Good oil and fuel resistance | Poor resistance to ozone, UV, and weathering |
| Wide operating temperature range | Limited performance in extreme cold |
| Good mechanical durability | Incompatible with polar solvents |
| Versatile formulations | Not ideal for high-temperature applications |
| Blendable | Not weathering resistant |
Looking for Nitrile Rubber products?
At Checkmate Flex, we supply high-quality nitrile rubber products across a wide range of grades, hardnesses, and formats. Get in touch with our team to discuss your requirements and we can advise the design and implementation of our flexible engineering.
