FEP
Definition and meaning of FEP in chemistry.
FEP (fluorinated ethylene propylene) is a fluoropolymer made by copolymerizing tetrafluoroethylene (TFE) with hexafluoropropylene (HFP), producing a plastic that combines PTFE-like chemical inertness with melt-processability.
In more detail
Replacing some fluorine atoms along the perfluorocarbon backbone with bulky trifluoromethyl side groups (from HFP) lowers the crystalline melting point compared to pure PTFE, so FEP can be melted and shaped by conventional extrusion or injection molding rather than requiring sintering. It retains the strong, highly polar C–F bonds that give fluoropolymers their exceptional resistance to solvents, acids, and bases, plus low friction, low dielectric constant, and excellent electrical insulation. Its main tradeoff versus PTFE is a somewhat lower maximum continuous-use temperature, around 200°C instead of roughly 260°C.
Key facts
| Repeat unit formula | –(CF2CF2)n–(CF2CF(CF3))m– |
|---|---|
| Monomers | Tetrafluoroethylene + hexafluoropropylene |
| Melting point | ~260 °C |
| Field | Organic Chemistry |
FEP is extruded into clear, chemically resistant tubing used to carry corrosive acids and ultrapure solvents in semiconductor fabrication and analytical laboratories.
Frequently asked questions
How is FEP different from PTFE (Teflon)?
FEP contains hexafluoropropylene units that disrupt the crystal structure enough to lower its melting point, so unlike PTFE it can be melt-processed by extrusion or molding; PTFE must be shaped by sintering and tolerates slightly higher temperatures.
Why is FEP used for lab and chemical-processing tubing?
Its fully fluorinated backbone is essentially inert to acids, bases, and organic solvents, and it can be extruded into flexible, transparent, low-friction tubing, making it ideal for handling corrosive or ultrapure fluids.