Flourocarbon Rubber (FKM)
FKMs (sometimes known as FPMs in Europe) are frequently used to resist extreme temperatures and harsh chemicals. The strong carbon-fluorine bonds that make up the polymer structure provide high thermo-chemical resistance, giving excellent ageing characteristics shown by low compression set at elevated temperatures.
FKMs offer excellent resistance to mineral oils and greases, aliphatic, aromatic and some chlorinated hydrocarbons, petrol and diesel fuels, silicone oils and greases. However FKMs show poor resistance to ethers, esters and amines.
FKMs are available as a copolymer (two monomers), terpolymer (three monomers) or as a tetrapolymer (four monomers). Each type determines both fluorine content and chemical structure which in turn significantly impact the chemical resistance and temperature performance of the polymer.
More recent innovations include the development of FKM materials for use in low temperature applications, where with a glass transition of -40°C, it is possible to use FKMs down to -51°C in service.
ERIKS 514322 brings true low temperature capabilities to chemically demanding and high temperature applications.
Types of Fluorocarbon Rubber
| ASTM D1418 Designation | Common Name | Typical Cure System | Typical Fluorine Content | Description |
|---|---|---|---|---|
| Type 1 | Viton® A | Bisphenol or amine | 66% |
General purpose with excellent mechanical properties |
| Type 2 | Viton® B, F or GF | Bisphenol, amine or peroxide | 66-70% |
Improved fluid and oil/solvent resistance, including improved fuel resistance. Peroxide cured materials offer improvements in coolant and water resistance |
| Type 3 | Viton® GLT | Peroxide | 64-67% |
Improved low temperature resistance but reduced chemical resistance |
| Type 4 | Aflas® | Peroxide | 55% |
Excellent resistance to lubricating oils, corrosion inhibitors and coolants |
| Type 5 | Viton® ETP | Peroxide | 67% |
Speciality grade, excellent chemical resistance, including increased resistance to amines and fuel additives |
| Ultra-low temp | Ultra-low temp | Peroxide | 66% |
Speciality polymers are available that further extend the low temperature performance of FKMs |
Viton® is a registered trademark of DuPont Performance Chemicals
Aflas® is a registered trademark of Asahi Glass