PTFE Tubing Or FEP Tubing?

                                                              PTFE tubing or FEP tubing


Which kind of PTFE or FEP to choose depends on the user's requirements. The common color of PTFE is milky white, followed by translucency and color. At present, transparency has not been invented. However, FEP replaces the disadvantages of PTFE, and the color of FEP is usually transparent.


In addition to the replacement of color, they have some differences in temperature resistance. PTFE has a high temperature resistance of 260 degrees and FEP has a high temperature resistance of 200 degrees. If transparent tubes are needed, and the high temperature resistance is 260 degrees, PFA can be used instead.



Next, I'd like to introduce the difference between PTFE and FEP.



Polytetrafluoroethylene (PTFE) is generally referred to as "non stick coating" or "easy to clean material". This kind of material has the characteristics of acid and alkali resistance, resistance to various organic solvents, and almost insoluble in all solvents. At the same time, polytetrafluoroethylene has the characteristics of high temperature resistance, and its friction coefficient is very low, so it can be used for lubrication, and also become an ideal coating for easy cleaning of the inner layer of water pipes.


The mechanical properties of polytetrafluoroethylene are relatively soft. It has very low surface energy. Polytetrafluoroethylene has a series of excellent performance:


High temperature resistance: long-term use temperature 200 ~ 260 ℃;



Low temperature resistance: soft at - 100 ℃;


Corrosion resistance: resistant to aqua regia and all organic solvents;


Weather resistance: the best aging life of plastics;


High lubrication: with the minimum friction coefficient of plastic (0.04);


Non adhesion: having the minimum surface tension in solid materials without adhering to any substance;


Non toxic: it has physiological inertia, excellent electrical performance, and is an ideal C-class insulation material. A thick layer of newspaper can block 1500V high voltage; it is smoother than ice.



The friction coefficient of polytetrafluoroethylene is only 1 / 5 of that of polyethylene, which is an important feature of perfluorocarbon surface. Because of the low intermolecular force between fluorine and carbon chain, polytetrafluoroethylene has no viscosity. Polytetrafluoroethylene has excellent mechanical properties in a wide range of temperature from - 196 ℃ to 260 ℃. One of the characteristics of perfluorocarbon polymer is that it is not brittle at low temperature. The density of PTFE is 2.14-2.20g/cm, almost no water absorption, and the equilibrium water absorption is less than 0.01%. Polytetrafluoroethylene (Teflon) is a typical soft and weak polymer. The interaction between macromolecules is small, the rigidity, hardness and strength are small, and it will deform under the long-term stress.


The structure characteristics of FEP material in transit are as follows:



Poly (perfluoroethylene propylene) (FEP) is a copolymer of tetraoxyethylene and hexafluoropropylene. The abbreviation is FEP. Poly (perfluoroethylene propylene) (FEP) is a straight chain polymer. The molecular chain can be regarded as the result that a fluorine atom connected to every four carbon atoms in the main chain of polytetrafluoroethylene is replaced by CF3. Compared with polytetrafluoroethylene, the symmetry and regularity of FEP molecular chain are broken, which makes the molecular chain With the decrease of rigidity and the increase of flexibility, the melting point of materials will decrease, the fluidity will increase, and the heat resistance will also be lower.



The damage of FEP regularity affects the crystallinity of the material, and the crystallinity will decrease. The polarity of FEP chain is still not shown. The density is 2.14-2.179/cm3, only the second polytetrafluoroethylene, the surface is as smooth as wax, the water absorption is not more than 0.01%.