Fluorinated ethylene propylene is colorless and transparent, the copolymerization of tetrafluoroethylene and hexafluoro- propylene, retained full performance of the F4, has excellent chemical stability, excellent non-stick characteristics of temperature permissions below F450 °C, forming convenient with extrusion, molding, injection molding.

1. FEP is milky white, translucent solid with the density of 2.14-2.18g/cm3, smooth surface such as wax, low water absorption, does not exceed 0.01%. Compared with the conventional mechanical properties are similar and toughness at room temperature and creep resistance is better than PTFE. But at elevated temperature is less than PTFE. Its mechanical properties are affected by temperature, but it still has a certain carrying capacity even at 200 ℃. The friction factor is only after to PTFE, and decreases with increasing load.
2. Chemical stability of FEP and PTFE is similar, for all of the dilute or concentrated inorganic acids and alkali it has exceptional stability. It is not affected with alcohols, ketones, hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, grease, etc. Only at elevated temperature, it has to ration with fluorine, alkali metals and chlorine fluoridation. Carbon tetrachloride and fluorine-containing compound make FEP swell but can still recover the original shape and performance after the departure of the solvent.
3. FEP has very excellent dielectric properties and electric insulation properties, close to PTFE, the electrical properties substantially unaffected by the influence of the electric field frequency and the environmental humidity change, which can be stable in a very wide temperature range. In addition, FEP has exceptional resistance weathering performance, excellent flame resistance and oxygen index is up to 95.
4. The principal shortcomings of FEP are the higher melting temperature and the higher viscosity. It needs to use higher molding pressure, but melt fracture phenomenon is easy to produce in the high shear rate. In addition, the intensity of FEP production of plastic parts is minimal, but the cost is very high.