Perfluorocarbons Kalrez® (FFKM)
The relative inertness of fluorocarbon rubbers is provided by fluorine-carbon bonds on the elastomer backbone. Generally speaking, with increasing fluorine content, resistance to chemical attack is improved. Where fluorocarbon rubbers have a fluorine content of 63 – 68 %, the perfluorocarbons have a fluorine content of 73%. Perfluorelastomers possess excellent resistance to extreme temperatures -26°C to +260°C (-15°F to +500°F). FFKM perfuoroelastomers: (Kalrez®) offers the best chemical resistance of all elastomers.
Some types are particularly suitable for hot water, steam and hot amines. Some resist temperatures up to +326°C (+620°F).
Many perfluorocarbon compounds have unusual mold shrinkage, production molds for perfluorocarbon products are different from molds for nitrile.