FFKM is perfluoroelastomer. The figure shows the chemical formula of FFKM as well as Teflon (PTEE: polytetrafluoroethylene) and viton, the fluorinated plastics containing higher amounts of fluoride. It is known to all that the fluorinated plastic and viton have superior heat and chemical resistance. The construction of FFKM consists of the main chain (TFE, tetrafluoroethylene), branched chain (PMVE, perfluorinated methyl ether) and the bridge connection, which are completely fluorinated, with the construction very similar to Teflon. On the other hand, the main chain of viton still contains hydrocarbon combination, with its binding force less than carbon-fluorine binding force and its heat and chemical resistance worse than FFKM.