Fluoroplastics refer to alkane polymers in which part or all of the hydrogen is replaced by fluorine. They mainly include polytetrafluoroethylene (PTFE), perfluoroethylene (ethylene propylene) copolymer (FEP), polyperfluoroalkoxy (PFA) resins, polytrifluoroethylene (PCTFE), ethylene-trifluoroethylene (ECTFE), ethylene-tetrafluoroethylene (ETFE) copolymer, polyvinylidene fluoride (PVDF) and polyvinyl chloride (PVF). Fluorine plastics have excellent flame resistance and heat resistance. Taking PTFE, PFA, FEP as an example, their applicable temperature range is usually between 260 ° C and 300 ° C. At the same time, fluorine plastics have excellent drug resistance and solvent resistance, and can resist the erosion of acids, alkalis and most solvents. However, it should be noted that molten alkali metals, fluorine, trifluorofluorocarbons will have a certain impact on it. In terms of electrical properties, fluorine plastics, especially in high-frequency properties, have incomparable advantages over other materials, and also have piezoelectric and pyroelectric properties.
Polytetrafluoroethylene (PTFE) : known as the "king of plastics", polytetrafluoroethylene (PTFE) is a crystalline polymer prepared by the free radical polymerization of tetrafluoroethylene, with many excellent properties. PTFE has excellent chemical resistance, low dielectric constant and is stable over a wide range of temperatures and frequencies. However, in terms of mechanical properties, the tensile strength, wear resistance and creep resistance of PTFE are slightly inadequate compared with other engineering plastics. However, it is worth mentioning that PTFE has an extremely low coefficient of friction, a very high oxygen index (OI), and a limiting oxygen index (LOI) of 95%. Because of this, PTFE has been widely used in many fields such as anti-corrosion, anti-corrosion pipes and accessories, heat exchangers, machinery, electronic and electrical appliances, medical materials, and micro-powders.
Polyperfluorinated ethylene propylene (FEP) : It is a crystalline polymer composed of tetrafluoroethylene and hexafluoropropylene, which is a soft plastic with a melting point of 304℃. In terms of mechanical properties, such as tensile strength, wear resistance and creep resistance, FEP is relatively weak. However, as a chemically inert material, FEP is not easy to burn, and the oxygen index is as high as 95%, which can effectively prevent the flame from spreading. At the same time, FEP also has good weather resistance and low friction coefficient, can be used in the range of low temperature to 392℃, and can be made into a variety of semi-finished products such as film, plate, rod and single fiber, which is widely used in the inner layer of pipeline and chemical equipment, drum surface and the production of various wires and cables.
Polytrifluorochloroethylene (PCTFE) : is a crystalline polymer caused by trifluorochloroethylene free radical polymerization, melting point of 217℃. At room temperature PCTFE is inert to most active chemicals and is only dissolved by a few solvents above 212 ° C. PCTFE's membrane products are excellent at blocking gases, and the water vapor permeability is the lowest of all clear plastic films. In addition, PCTFE has a slightly higher dielectric constant and loss factor in terms of electrical properties, especially at high frequencies.
Polyvinylidene fluoride (PVDF) is a homopolymer or copolymer of vinylidene fluoride with a fluorine content of about 60%. It has excellent chemical resistance, high temperature resistance, oxidation resistance, weather resistance, ultraviolet resistance and high temperature radiation resistance. Its tensile and impact strength, hardness and wear resistance are excellent, and its thermal deformation temperature and creep fatigue resistance are also excellent. PVDF is a strong structural material with a temperature range of -60~150℃. Because of its good chemical resistance and processability, PVDF is often used to make pumps, valves, pipes, pipe fittings, storage tanks and heat exchangers for petrochemical equipment. It is also used in lithium secondary batteries, such as making porous membranes, gels, diaphragms and binders.
Fusible polytetrafluoroethylene (PFA) is a perfluorinated fluorine plastic, similar to PTFE, with many excellent properties and the ability to melt at lower temperatures. PFA is obtained by the copolymerization of a small amount of perfluoro propyl perfluoro vinyl ether and polytetrafluoroethylene, and its properties are almost unchanged from that of polytetrafluoroethylene. PFA has a temperature range of -80 ° C to 260 ° C for long-term use, has excellent chemical resistance, is one of the lowest friction coefficient of plastics, and also has good electrical properties and physiological inertia. In addition, the creep resistance, compressive strength and tensile strength of PFA are better than that of polytetrafluoroethylene, and the elongation can reach 100-300%. Therefore, PFA is suitable for the production of corrosion resistant parts, wear resistant parts, seals, insulation parts and medical device parts.
Polyvinyl fluoride (PVF) : It is a white powdered partially crystalline polymer with a melting point of 190-200 ° C, decomposition temperature above 210 ° C, and long-term use temperature of -100-150 ° C. PVF is a homopolymer of ethylene fluoride, with a molecular weight between 60,000 and 180,000. Polyvinyl fluoride is a white partially crystalline polymer with high melting point, high chemical resistance and high transparency. As one of the fluorine plastics with the lowest fluoride content, the smallest specific gravity and the cheapest price, PVF has a crystal structure and high tenacity. PVF film has high resistance and durability, and can be used in agricultural film, material protection, packaging and electrical insulation.
Fluoroplastics are a class of polymer materials with a variety of excellent properties, which play an important role in many fields such as industry, electronics, and medical treatment. With the development of science and technology and the continuous improvement of material performance requirements, the market demand for fluorine plastics and its products is expected to continue to grow.
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