PFA, FEP, PTFE, and Tefzel* are all Teflon* insulating materials. What is the difference?

There are many materials used for electrical insulation that belong to the Teflon family of fluoropolymers. Most of these materials were pioneered by the E.I. DuPont company, who still is the largest producer of most, if not all, of them. These materials include fluorinated ethylene-propylene (FEP), perfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene copolymer (Tefzel). These materials have a number of similarities; excellent resistance to hostile chemical environments, moisture, flame and flame spread, and good characteristics as electrical insulators. They do have some important differences. Tefzel is only rated for continuous exposure to 150 C temperatures, but is tougher and more resistant to mechanical abuse and damage. FEP is rated to 200 C and gives off almost no smoke when it is burned. PTFE and PFA are both rated for exposure to temperature to 250 C. Both of these materials have very good resistance to the effects of outdoor exposure, including carbon arc, sunlight and rain.

NOTE: * Teflon and Tefzel are registered trademarks of E.I. DuPont de Nemours & Company.