FFKM

FFKM stands for fully fluorinated elastomer, a class of synthetic elastomers known for extreme chemical resistance and high-temperature stability. Also referred to as perfluoroelastomers, FFKMs are among the most chemically resistant members of the fluoropolymer elastomer family and are designed to seal or gasket in environments where conventional elastomers fail. They form a dense, crosslinked network that remains elastic under harsh fluids.

The typical FFKM backbone comprises fully fluorinated monomer units, often copolymers of tetrafluoroethylene (TFE) with perfluoromethyl vinyl ether (PMVE) or similar comonomers, sometimes with additional fluorinated segments. Crosslinking is achieved through peroxide- or amine-initiated cure systems, producing a robust, chemically resistant network with low swell in aggressive media.

FFKMs exhibit outstanding chemical resistance to mineral acids, bases, oxidizers, hydrocarbons, and many solvents, and can operate at high temperatures, commonly up to 200–300°C depending on grade. They also have low gas permeability and maintain elasticity over a wide temperature range. Limitations include higher cost and more complex processing compared with conventional elastomers, as well as reduced low-temperature flexibility for some formulations.

Commercial FFKMs are marketed under brand names such as Kalrez and Chemraz, among others. They are widely used in seals, O-rings, and gaskets in chemical processing, pharmaceutical, semiconductor, and oil and gas equipment, especially where concentrated corrosives, high-temperature steam, or aggressive solvents are involved.