Polytetrafluoroethylene (PTFE for short), commonly known as "the king of plastics", is a polymer prepared by polymerization of tetrafluoroethylene as monomer. Its chemical formula is (C2F4)n, which has excellent heat and cold resistance and can be used for-180 ~ 260? C long-term use.
This material has the characteristics of acid resistance, alkali resistance and resistance to various organic solvents, and is almost insoluble in all solvents. At the same time, PTFE has the characteristics of high temperature resistance and very low friction coefficient, which can be used for lubrication and become an ideal coating for easy cleaning of water pipes.
Monomer tetrafluoroethylene is prepared from chloroform by fluorinating chloroform with anhydrous hydrofluoric acid and antimony pentachloride as catalyst at the reaction temperature above 65℃, and finally pyrolysis. Tetrafluoroethylene can also be prepared by the reaction of zinc with tetrafluoroethylene dichloride at high temperature.
Preparation of PTFE in enamel or stainless steel polymerization kettle, with water as medium, potassium persulfate as initiator, ammonium perfluorocarboxylate as dispersant and fluorocarbon as stabilizer, PTFE was prepared by redox polymerization.
application area
1. Anticorrosion: PTFE material is widely used in petroleum, textile and many other industries because of its excellent corrosion resistance. Representative exhaust pipes, steam pipes, high, medium and low pressure pipes and valves. Especially in the harsh environmental conditions where conventional materials such as low temperature and anti-sticking cannot be used, PTFE has more advantages.
2. Electronic and electrical aspects: PTFE has a relatively small dielectric constant, which can be used to prepare enameled wires and micro-motors. In addition, fluoroplastic films have certain selective permeability to various gases, so they can be used to prepare oxygen sensors. Nowadays, various forms of PTFE materials have played an important role in the field of electronic and electrical insulation.
Teflon glass lacquer cloth and glass cloth are used to make high-temperature and high-frequency insulating materials, which can be used in satellite communication and computers. Polytetrafluoroethylene film is used to make capacitors, as insulation layer, gasket and cable between instruments. Thin-walled PTFE pipes with different diameters are used for outlet bushings, heat shrinkable pipes and spiral pipes, insulated water diversion pipes for generators, etc.
3. In medical treatment: PTFE has excellent biocompatibility. In recent years, many people have conducted in-depth research on it as a biomaterial. In recent years, PTFE membranes have been developed as artificial organs at home and abroad, such as artificial blood vessels and heart valves. For example, it has been used as a prosthetic stent material for artificial blood vessels and nasal plastic surgery in clinic, and achieved good results.
4. In architecture: by coating PTFE resin on superfine glass fiber fabric, PTFE membrane has the characteristics of light weight, high strength, fire prevention, good self-cleaning, no influence of ultraviolet rays, fatigue resistance, torsion resistance, aging resistance, long service life, high light transmittance and less heat absorption. It is precisely because of this intergenerational invention of membrane materials that membrane structure architecture has become a modern permanent building.
5. Low friction performance in terms of load: Due to its relatively low friction coefficient compared with most solid materials, filled PTFE has gradually evolved into an excellent material for oil-free lubrication of various parts. It is widely used, including bearings of chemical equipment, piston rings, supporting sliders of steel roof trusses and bridge swivel rings.
The above contents refer to Baidu Encyclopedia-PTFE.