A widely used elastomer, Nitrile, Buna-N, or NBR rubber, are all oil and fuel resistant and provide a great level of strength, making them a popular material for seals across various industries.
Suitable for a range of applications, this versatile rubber material, like any, comes with a range of advantages and disadvantages, which you must know about before opting for Nitrile for your application.
Of course, specialist o ring suppliers such as Specialist Sealing Products are always on hand to provide you with further information and advice, stocking hundreds of different o rings and gaskets manufactured from varying compounds and materials.
Buna-N
Buna-N (most commonly known as Nitrile) is the most frequently used and most economical elastomer around.
Resistant to fuels, petroleum-based oils, water, silicone greases, alcohols, and hydraulic fluid, this material can provide you with a whole host of benefits.
It also works well in low compression sets and can provide users with high resistance to abrasion and tensile strength.
NBR (Buna N) has a temperature range between -40 degrees Fahrenheit to 257 degrees Fahrenheit with a hardness range between 40 to 90 Share A.
Note: You can formulate NBR compounds to offer different temperature ranges, i.e., from -85 degrees Fahrenheit to 275 degrees Fahrenheit, if required, depending on use and application.
NBR rubber properties
Nitrile rubber is composed of copolymers (unsaturated) of 2-propenentile and butadiene monomers. Of course, Nitrile’s chemical and physical properties will vary depending on the polymer’s composition.
It’s also important to note that the more Nitrile there is within the polymer, the higher the level of resistance it will have to oils, but the less flexibility it will be able to offer you, compared to natural rubbers, for example.
Comparing Nitrile rubber to natural rubber further, we find that Nitrile is also more resistant to acids, oils and is stronger.
The NBR compound formulation can comprise filler, plasticizer, antioxidant or antiozonant, zinc oxide, accelerator, and vulcanising agents.
These elements will be used to help increase the sealing properties required from the material.
The most commonly used is that of carbon black. Used as a filler in standard NBR compounds, depending on the volume of carbon black filler used will depend on the hardness of the final compound.
In contrast, plasticizers will increase the processability of the compound, modifying its physical properties creating modifications that can help lower hardness, improve flexibility, and lower temperature performance.
For most NBR compounds, sulphur is typically used as the curing agent of choice.
When systems have been exposed to sulphur as the curing agent, vulcanising agents and accelerators will then be used to help speed up reaction rates between the sulphur and the NBR.
For further information on sealing properties and the right material choice for your seal and application, make sure to read our latest post relating to oil seals here.
What are NBR seals suitable for?
NBR seals are suitable for:
- O rings
- Oil seals
- Gaskets
- Hoses
- Automotive transmission belts
- Synthetic leather
- Belts
- Printers foam rollers
- Disposable non-latex gloves
- Cable jacketing
- And more.
It is also possible to use NBR latex as a pigment binder or in the preparation of adhesives.
NBR seals are most commonly found in the automotive industry, but overall, they are a great material choice for any oil-based application.
Used in low-temperature military applications, off-roading equipment, marine devices, aircraft fuel systems, and more.
In addition, for NBR formulated to FDA standards, it can also increase the many ways NBR o rings can be applied.
Advantages and disadvantages of Buna-N
Advantages
- Abrasion-resistant
- It offers a rebound element
- Tear-resistant
- It offers excellent sealing capabilities, all at a very low cost
- Non-polar solvent resistant
- Water-resistant
- Provides a low compression set
- Has low gas permeability
- Oil resistant
- Less expensive than Fluoroelastomers.
Disadvantages
- Poor resistance to sunlight, weather, and ozone
- Limited resistance to high temperatures
- Should have limited contact with highly aromatic fuels and glycol-based brake fluids
- Poor flame resistance.
To find out more about Nitrile rubber and the most suitable o rings and gaskets in the UK for your application, call us today on 01535 274 776; a member of our team will be happy to help.
