8 - Polymerization and Finishing of Tetrafluoroethylene

Abstract

Tetrafluoroethylene (TFE) is the main constituent monomer for the preparation of polytetrafluoroethylene (PTFE) resins. TFE is polymerized in an aqueous suspension medium to produce granular PTFE resins. These polymers are produced by the polymerization of TFE and the addition of trace amounts of a comonomer to modify the TFE homopolymers. After the completion of the polymerization, a “raw” dispersion of PTFE particles in water is obtained, which must be “finished” before commercial application is possible. Raw dispersions produced by dispersion polymerization contain a wide range of PTFE solids, often, in the range of <10–45% by weight in water. Fine powder PTFE is produced by polymerization dispersion using coagulation, dispersion, and drying processes. High molecular weight polymers of chlorotrifluoroethylene (CTFE) are synthesized, characterized, and utilized in the diffusion process to produce polychlorotrifluoroethylene (PCTFE). The synthesis of CTFE has been carried out by bulk, suspension, and emulsion polymerizations.