Fluorinated Ethylene-Propylene - FEP

Fluorinated Ethylene Propylene Copolymer (FEP) is a semi-crystalline perfluorinated polymer closely linked to PTFE (FP30) being a copolymer of tetrafluoroethylene and hexafluoropropylene.

Its properties are similar, but mostly a little low-grade to, those of PTFE but it has the excellent practical advantage of being melt-processable (though more expensive).

Compared in more detail to PTFE, it has equally superior chemical resistance and electrical properties (up to very high frequencies) and good weathering resistance.

It has improved radiation resistance and a lot higher impact strength but has lower maximum use and heat deflection temperatures and is even a little less stiff and robust.

Though not quite crystal clear, it is transparent (fundamentally from 250/300 to 7000 nm) and colorless or with a minor bluish tinge.

Polymer Type



The advantage of FEP are its high impact strength, excellent high frequency electrical properties, melt processable and good weathering resistance.


FEP can be very expensive, with the lowest strength and stiffness of all the fluoro plastics. Low HDT at c 50 °C ( 120 °F ) accompanied by poor wear resistance.


Applications include of  Fluorinated Ethylene Propylene Copolymer (FEP) include chemical and medical equipment, chemical apparatus, wire coverings, extruded insulation and glazing film for solar panels, and coatings and protective linings.

FEP can be used for the glazing film of solar panels. Image Credit: ShutterStock/ZHANGXIAOLI

FEP can be used for the glazing film of solar panels. Image Credit: ShutterStock/ZHANGXIAOLI

Typical Properties

Property Value
Density (g/cm3) 2.1
Surface Hardness RR45
Tensile Strength (MPa) 14
Flexural Modulus (GPa) 0.6
Notched Izod (kJ/m) 1.06+
Linear Expansion (/°C x 10-5) 5
Elongation at Break (%) 150
Strain at Yield (%) 6
Max. Operating Temp. (°C) 150
Water Absorption (%) 0.01
Oxygen Index (%) 95
Flammability UL94 V0
Volume Resistivity (log ohm.cm) 18
Dielectric Strength (MV/m) 50
Dissipation Factor 1 kHz 0.0002
Dielectric Constant 1 kHz 2.1
HDT @ 0.45 MPa (°C) 70
HDT @ 1.80 MPa (°C) 50
Material. Drying hrs @ (°C) NA
Melting Temp. Range (°C) 340 - 360
Mould Shrinkage (%) 2.5
Mould Temp. Range (°C) 50 - 200

Source : Abstracted from Plascams

For more information on Plascams please visit RAPRA Technology Ltd.

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