Fluoroplastics have excellent heat resistance, cold resistance, weather resistance, drug resistance, solvent resistance, insulation and high frequency performance, and have the characteristics of non-drying, self-lubrication and low friction coefficient.
Polytetrafluoroethylene and perfluoroethylene-propylene copolymer (FEP) are composed entirely of carbon atoms and fluorine atoms, while polyvinylidene fluoride (PVDF) and polyfluoroethylene (PVF) also contain hydrogen atoms, while polytrifluoroethylene (PTFC) also contains chlorine atoms. The excellent properties of fluoroplastics are realized by the high binding energy between carbon atoms and fluorine atoms. Polytetrafluoroethylene (PTFE) has high performance because its main chain skeleton is carbon atom surrounded by fluorine atom, while PFA, FEP, ETFE and other varieties have changed their softening point low-molecular PTFE due to the influence of side groups.
1. Thermal fluoroplastics have flame retardancy and excellent heat resistance. The continuous use temperature of PTFE and PFA can reach 260 C, and can be used at 300 C for a short time. The temperature of FEP is 60 C lower than that of FEP. The * height of PCTFE can be used at 120 C. If fluoroplastics are used at high temperature for a long time, the crystallinity of fluoroplastics will change, especially when making lining of equipment.
2. Resistant fluoroplastics have excellent resistance to drugs and solvents, especially PTFE, PFA, FEP, etc. They are not corroded by acids, alkalis and solvents. However, molten alkali metals, fluorine and CFCs have different effects on them. The resistance of PCTFE, ETFE and PVDF in fluoroplastics is slightly worse, but the corrosion resistance of PCTFE, ETFE and PVDF is much better than that of other plastics.
3. Electrical properties of fluoroplastics, especially high-frequency electrical properties, are incomparable with other materials. The polarity of PTFE, FEP and PFA molecules is very low, and the change of temperature and frequency is very small in a wide range. The relative dielectric constant is stable, the dielectric loss is very low, and the electrical insulation is excellent. Among them, PVDF has special piezoelectric and pyroelectric properties, which can be used to manufacture piezoelectric materials.
4. The tensile strength of fluoroplastics increases with the increase of hydrogen and chlorine atoms in fluoroplastics molecule. PTFE and
The brittleness temperature of PCTFE is very low, which shows excellent low temperature performance. PTFE has * low friction coefficient and special self-lubrication
Slip. But PTFE has its own shortcomings such as large wear and cold flow. It can be filled with various fillers to improve wear resistance and overcome cold flow.
5. Non-sticky fluoroplastics have special non-stickiness. Especially, the fluorine content in molecules such as PTPE, FEP and PFA is high, and the contact angle on the surface is very large, which makes the liquid on the surface of fluoroplastic products globular. It is not easy to bond with resin, so it is often used to make non-stick layer on the surface of cooking utensils.
6. All kinds of fluoroplastics have excellent weatherability. Even if they are exposed to severe temperature for a long time, their various properties remain unchanged.
7. The water absorption rate of hydrophobic fluoroplastics is low, especially PTFE. Its hydrophobicity can be used to make breathable and impermeable composite fabrics and other equipment.