What is FEP

What is Fluorinatedethylenepropylene? (FEP)

Fluorinatedethylenepropylene (FEP) is a copolymer of hexafluoropropylene and tetrafluoroetheylene that shares PTFE’s chemical resistance and useful low friction properties, but is more easily formable. FEP was invented by Dupont and developed as a melt processable version of PTFE.

FEP is sold under various brand names, the name ‘Teflon®’ is often mistaken to only refer to the fluoropolymer PTFE, but FEP and PFA also come under this title. FEP is softer, slightly more flexible, but does not withstand repetitive folding as well as PTFE. It also possesses inferior coefficient of dynamic friction and slightly lower tensile strength. Fluorinatedethylenepropylene stands out thermally from PTFE by its lower melting point of 260°C and is highly transparent and resistant to sunlight.

FEP is vastly superior in some coating applications involving exposure to detergents. The main differences between FEP and PTFE are in regards to chemical inertness, corrosion resistance, permeability, and FDA approval.

Being able to maintain chemical composure in extreme temperatures and resist damage from chemical fuels makes FEP a good choice in the Aerospace industry as release film, preventing the curing adhesive (such as carbon fibre) from bonding to the metal tooling.

With flexibility, extreme resistance to chemical attack and optical transparency, FEP is a suitable choice for plastic lab equipment and tubing.

Properties Value Units Methods
Specific Gravity 2.1-2.3   ASTM D792-66
Processing Temperature 320 oC  
Tensile Strength @ 23oC





Elongation @ 23oC 240-300 %  
Flexural Modulus @ 23oC No Break at Flexure   ASTM D790
Coefficient of Friction 0.27-0.67   ASTM D1894
Impact Strength No Break    
Dielectric Strength 13-100 KV.mm-1 ASTM D149
Melting Point 253-282 oC  
Upper Service Temperature (20,000h) -250 to 200 oC  
Flame Rating + V0   UL94
Limiting Oxygen Index 95 % Oxygen ASTM D2863

The information in this table represents typical figures intended for reference and comparison purposes only 

Our Fluorinoid® FL304, virgin FEP is often used in fluid handling applications such as O rings, valves, back up rings and seats.

Key features:

  • Excellent Thermal Stability
  • Chemically Inert to almost all Chemicals and Solvents
  • Retains its properties even after prolonged exposures to harsh chemical environments
  • FDA Approved
  • Non-stick quality unsurpassed by any plastic
  • High Transparency with good transmittance of UV rays and visible rays up to 98%
  • Lowest refractive index of all plastics, providing low light reflection
  • Refractive index of water, virtually invisible in water
  • Non Porous
  • Excellent Resistance to Ozone, Sunlight and Weather
  • Inert to Body Tissue
  • Low Dielectric Constant and High Dielectric Strength

To find out how we can support your projects contact info@fluorocarbon.co.uk