Key Difference – Buna N vs Viton
Buna N and Viton are commercial names for butadiene-acrylonitrile (nitrile rubber) and vinylidene fluoride-hexafluoropropylene copolymer, respectively. Both these elastomers are widely used synthetic elastomers that possess a unique set of physical and chemical properties. The key difference between Buna N and Viton is that Buna N is a copolymer of butadiene and acrylonitrile, whereas Viton is a copolymer that contains a high amount of fluorine-containing units. Due to the difference in the chemical structure of these two materials, they exhibit a different set of properties, which will be discussed in this article.
What is Buna N?
Buna N® is the registered trademark of Pittway Corporation, Chicago for nitrile rubber or NBR, which is produced by the polymerization of two monomer units: acrylonitrile and butadiene. The monomer ratio varies depending on the desired properties of the end-product. Usually, cyanide group in acrylonitrile group enhances the oil and solvent resistance; thus, the amount of acrylonitrile determines the oil resistance level of Buna N.
Buna N can operate in a wide range of temperature from – 40 °C to 120 °C; this enables Buna N to be used in extreme automotive applications including hoses, seals, belts, oil seals, etc. Since, Buna N is resistant to hydrocarbon solvents esters, ketones, and aldehydes; it is widely used to make laboratory gloves. Buna N is also used to form adhesives, foams, floor mats, synthetic leather, and footwear.
What is Viton?
Viton® is the registered trademark of DuPont DOW Elastomers L.L.C, Wilmington for specialty fluoroelastomer, which contains a high amount of fluorine-containing units. Viton has excellent chemical resistance to acids and alkalis, high-temperature resistance (up to 275-300 °C for a short period), excellent oxidation resistance, and good resistance to fuel containing about 30% of aromatics. There are various grades of Viton in the market for general purposes and special purposes. General-purpose Viton grades are Viton® A, Viton® B, and Viton® F, and special-purpose Viton grades include GB, GBL, GF, GLT, and GFLT. All these grades can cover various manufacturing processes such as injection and transfer molding, compression molding, calendaring, and extrusion.
Viton A is produced by the polymerization of vinylidene fluoride (VF2) and hexafluoropropylene (HFP). It is used for general molded o-rings, gaskets, and other simple and complex shaped molded products. Viton B is polymerized from three monomers, including vinylidene, hexafluropropylene, and tetrafluoroethylene. Viton B offers better fluid resistance properties than Viton A. Viton F is also made by the polymerization of three monomers vinylidene, hexafluropropylene, and tetrafluoroethylene and has better fluid resistant properties of all other Viton grades; thus, it is useful in fuel permeation resistant applications. Viton GBL is resistance to steam, acid and engine oils, and Viton GLT shows high heat and chemical resistance, and low-temperature flexibility. Viton GFLT has high heat and superior chemical resistance and is used in high-performance applications. Both Viton GLT and GFLT have low glass transition temperature compared to general-purpose Viton grades.
What is the Difference Between Buna N and Viton?
Buna N vs Viton
|Buna N is the commercial name for nitrile rubber/ NBR.||Viton is the commercial name for fluoroelastomer.|
|Monomers used in Manufacturing|
|Acrylonitrile and butadiene are used to manufacture Buna N.||Vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene are used to manufacture Viton.|
|Buna N is oil and solvent resistant.||Viton has high-temperature resistance and chemical resistance.|
|Buna N has a temperature resistance up to about 120 °C.||Viton has a temperature resistance up to about 300 °C.|
|Buna N is used to manufacture il seals, laboratory gloves, fuel pumps, etc.||Viton is used in extreme automotive applications such as gaskets, seals, kitchen utensils, etc.|
Summary – Buna N vs Viton
Both Buna N and Viton are trademarks of two important synthetic elastomers: nitrile rubber and fluoroelastomer, respectively. Buna N is made from copolymerization of acrylonitrile and butadiene, and has excellent oil resistant properties, whereas Viton is made from copolymers of vinylidene fluoride-hexafluoropropylene, and has excellent high temperature, chemical and oxidative resistant properties. This is the difference between Buna N and Viton.
Download PDF Version of Buna N vs Viton
You can download PDF version of this article and use it for offline purposes as per citation note. Please download PDF version here Difference Between Buna N and Viton.
1. Stoltzfus, Joel M., and Kenneth McIlroy. Flammability and sensitivity of materials in oxygen-Enriched atmospheres. Philadelphia, PA, ASTM, 1991.
2. Carraher Jr, C. E. Carraher’s polymer chemistry. CRC Press.2010.
3. O’Hanlon, J. F. A user’s guide to vacuum technology. John Wiley & Sons,2005.
4. Cardarelli, F. Materials handbook: a concise desktop reference. Springer Science & Business Media,2008.