Chemical structure of the compounds referred in the text. Skeletal structures of (a) PTFE (polytetrafluoroethylene) and Viton rubber. (b) CF3− can be replaced by CF3O−, and up to several percent of fluorine can be replaced by hydrogen. (c) FEP (perfluoroethylenepropene). (d) Kapton H, a polyimide resin. (e) Poly(amic acid), a starting material for industrial production of the compound IV. (f) Hydrazide, a hydrazinolysis product of the polyimide resin IV. The polyimide resin IV generates (g) arylether VII and (h) hydrazide VIII via (f) hydrazide VI in the presence of hydrazine.