TetraFluorEthylene-Perfluorpropylene (FEP) is produced by copolymerization of tetrafluoroethylene and hexafluoropropylene. It is a relatively soft thermoplastic with lower tensile strength, wear resistance, and creep resistance than many other engineering plastics. However, it is chemically inert and has a low dielectric constant over a wide frequency range. FEP possesses a very high degree of stress crack resistance, a low coefficient of friction, exceptional dielectric properties, heat resistance, retention of properties after service at 400°F (204°C) with useful properties at -454°F (-270°C), and meets FDA 21CFR.177.1550.
FEP has high transparency (with good transmittance of UltraViolet and visible wavelengths). It has long term weatherability and excellent resistance to ozone, sunlight and weather. FEP offers the lowest refractive index of all thermoplastics with low light reflection (the same as water).
Important applications are linings for pipe and chemical processing equipment, roll covers, and numerous wire and cable applications, including aircraft wire, plenum cable, fire alarm cable, and well logging cable.