FEP (fluorinated ethylene propylene) is a copolymer of hexafluoropropylene and tetrafluoroethylene. Because FEP is poorly soluble in almost all solvents, the polymerization is conducted as an emulsion in water, using a surfactant such as perfluorooctanesulfonic acid.
FEP was invented by DuPont and is sold under the brand name Teflon® FEP. Other brand names are Neoflon® from Daikin or Dyneon® FEP from Dyneon/3M.
FEP is very similar in composition to the fluoropolymers PTFE and PFA. FEP and PFA both share PTFE’s useful properties of low-friction and non-reactivity but are more easily formable. FEP differs from the PTFE resin in its maximum operating temperature and its color. Since FEP is melt-processible, conventional injection molding and screw extrusion techniques can be used. It is highly transparent and resistant to sunlight.
In terms of corrosion resistance, FEP is the only other readily available fluoropolymer than can match PTFE’s resistance to caustic agents. Due to its flexibility, extreme resistance to chemical attack and optical transparency, this material is commonly used for plastic labware and tubing that involves critical or highly corrosive processes. Being able to maintain chemical composure in extreme temperatures and resist damages from chemical fuels makes FEP a suitable choice in the industry.
- Lower maximum operating temperature than PTFE (melting point: 205 °C, 260 °C for PTFE)
- Very low coefficient of friction
- Chemically inert
- Easy formable
- Low dielectric constant (insulating)
- Melting point of 260 °C
- Hookup wire, coaxial cable, wiring for computer wires and technical gear
- Protect molds during curing process (aerospace)
- Pipes, round bars, sheets for lining containment vessels, gas scrubbers, tanks in chemical-processing industry
- Build plate in 3D-printing
- Microscopy applications