What is FKM (Viton®)?

FKM (by ASTM D1418 standard) (equivalent to FPM by ISO/DIN 1629 standard) is the designation for about 80% of fluoroelastomers as defined in ASTM D1418.
Fluorocarbon rubber is the most significant single elastomer. Highly fluorinated carbon-based polymers used in applications to resist harsh chemical and ozone attack. The name Viton ® is trademark of Dupont.

Fluorocarbon elastomers are important in the seal industry and the O-rings are a solution for mechanical devices requiring maximum resistance to elevated temperatures and to many fluids such as the use in aircraft, automobile and other FKM has a high temperature range between -26°C to +205°/230°C (-15°F to +400°/440°F). For short working periods it will take even higher temperatures. It has a wide range of chemical compatibility, temperature range, low compression set, and excellent aging characteristics. Besides this it is flame-retardant but dangerous after a fire. Due to fluorine residues in the carbon residues, the material is heavy material and a stiffer elastomer.

FKM has a good resistant to mineral oils and greases, aliphatic, aromatic and also special chlorinated hydrocarbons, petrol, diesel fuels, silicone oils and greases. It is also suitable for high vacuum applications. Other fluorinated elastomers are perfluoro-elastomers (FFKM) and tetrafluoro ethylene/propylene rubbers (FEPM). All FKMs contain vinylidene fluoride as a monomer. Originally developed by DuPont (Viton), FKMs are today also produced by Daikin Chemical (Dai-El), 3M’s Dyneon (Dyneon Fluoroelastomers), SolvaySpecialty Polymers (Tecnoflon), HaloPolymer (Elaftor) and several Chinese manufacturers.

Fluoroelastomers are more expensive than neoprene or nitrile rubber elastomers. They provide additional heat and chemical resistance. FKMs can be divided into different classes on the basis of either their chemical composition, their fluorine content or their crosslinking mechanism. Many fluorocarbon compounds have a higher than normal mould shrinkage rate, moulds for fluorocarbon products are often different from moulds for Nitrile.

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