fluorelastomer

Fluorelastomer is a fluorinated elastomer, commonly marketed as FKM, used for seals and gaskets exposed to high temperatures and chemical attack. The fluorinated backbone provides resistance to oils, fuels, solvents, and steam, making fluoroelastomers a standard choice in automotive, aerospace, and chemical processing.

Two major families are recognized. FKM refers to vinylidene fluoride-based copolymers with comonomers such as hexafluoropropylene. FEPM is a terpolymer of tetrafluoroethylene, propylene, and a cure-site monomer, offering improved low-temperature flexibility and certain chemical resistances. A further class, perfluoroelastomers (FFKM), are fully fluorinated and provide the broadest chemical resistance and highest temperature capability, at higher cost. Common trade names include Viton (FKM), Fluorel, Tecnoflon, and Aflas (FEPM), with Kalrez representing FFKM.

Typical properties include service temperatures from roughly −20 to 250 C, excellent resistance to hydrocarbon fuels and mineral oils, and good compression set. They have poorer low-temperature elasticity than silicone elastomers and may swell in some ketones or strong bases. Price and processing difficulty are factors.

Processing relies on specialized curing systems and molding or extrusion. Many FKM and FEPM formulations cure with fluorinated curatives or peroxides and are processed by compression, transfer, or injection molding. Material selection depends on chemical exposure, temperature, and the mechanical demands of the seal.

Applications include seals, o-rings, gaskets, and hoses in automotive engines, aerospace hardware, and chemical-processing equipment. FFKMs serve the most aggressive chemical environments, while standard FKMs and FEPMs cover a broad range of less demanding service.