Basic properties of fluorine plastics

Fluoroplastic is a general term for polymer compounds containing fluorine atoms in the main chain of molecules. Fluorine plastics have excellent heat resistance, cold resistance, weather resistance, drug resistance, solvent resistance, insulation properties and high frequency electrical properties. It has the characteristics of non-drying, self-lubricating, low friction coefficient and so on.

Polytetrafluoroethylene, perfluorinated (ethylene-propylene) copolymer (FEP) is entirely composed of carbon and fluorine atoms, while polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF) molecules also contain hydroproons, polytrifluoroethylene chloride also contains chlorine atoms. The excellent properties of fluoroplastics are achieved by the high binding energy between carbon atoms and fluorine atoms. The backbone of polytetrafluoroethylene is carbon atoms, and it is completely surrounded by fluorine atoms, so its various properties are higher, and PFA, FEP, ETFE and other varieties due to the influence of the side group, the softening point is low PTFE, and other properties have also changed.

1. Thermal performance: fluorine plastics have flame resistance and excellent heat resistance. The continuous use temperature of PTFE and PFA can reach 260 ° C, and it can be used at 300 ° C for a short time. FEP is used at temperatures 60 ° C lower than they are. The higher PCTFE can be used at 120℃. Fluoroplastics such as long-term use at high temperatures will cause crystallinity changes, especially when manufacturing equipment lining.

2. Drug resistance: fluorine plastics have excellent drug resistance and solvent resistance, especially PTFE, PFA, FEP, etc., acid, alkali, solvent are not etched on them. But molten alkali metals, fluorine, trifluorofluorocarbons have different degrees of influence on them. PCTFE, ETFE, PVDF, etc., are slightly less resistant to drugs in fluoroplastics, but the corrosion resistance is still much better than that of other plastics.

3. Electrical properties: The electrical properties of fluorine plastics, especially the high-frequency electrical properties, are difficult to match other materials. The polarity of PTFE, FEP and PFA molecules is very low, the change is very small in a wide temperature and frequency range, the relative dielectric constant is stable, the dielectric loss is very low, and the electrical insulation is excellent. PVDF also has specific piezoelectric and pyroelectric properties, which can be used to manufacture piezoelectric materials.

4. Mechanical properties: The increase of hydrogen and chlorine atoms in fluorine plastic molecules will also increase its tensile strength. PTFE and PCTFE have extremely low embrittlement temperatures, showing excellent low temperature properties. PTFE has a low coefficient of friction and special self-lubricity. However, PTFE has its own shortcomings such as high wear and cold flow. Various fillers can be used to improve wear resistance and overcome cold flow.

5. Non-stickiness: fluorine plastics have specific non-stickiness. In particular, the fluorine content of PTPE, FEP, PFA and other molecules is high, and the surface contact Angle is very large, so that the liquid on the surface of fluoroplastic products becomes spherical. It is not easy to bond with resin, so it is often used to make non-stick creep layer on the surface of cookware.

6. Weather resistance: all varieties of fluorine plastics have excellent weather resistance, even in harsh temperatures for long-term exposure, its various properties have not changed.

7. Hydrophobicity: The water absorption of fluorine plastics is low, especially PTFE. Its hydrophobicity can be used to make permeable composite fabrics and other equipment.

Characteristics and uses of the main varieties of fluorine plastics