PTFE has high temperature resistance (can be used in the temperature range of 200~260 °C for a long time), low temperature resistance (can be used for a long time below -100 °C), corrosion resistance (high chemical inertness), weather resistance (high resistance to Atmospheric aging performance), high lubrication (with a very small coefficient of friction), non-adhesive (very low surface tension, not easy to adhere), good human compatibility (very good physiological inertia, non-toxic), electrical insulation Good (high insulation, and not affected by temperature and humidity) and a series of advantages in use, these characteristics of PTFE are closely related to its molecular configuration.
The molecular structure of PTFE is similar to that of polyethylene. It is a symmetrical and unbranched linear polymer, so the molecule does not show polarity, as shown in the figure below:
Due to the strong mutual repulsion between the unbonded fluorine atoms in the molecules, the carbon chain of PTFE is twisted to form a helical structure, and the fluorine atoms just completely cover the main chain of carbon atoms, which prevents the carbon atoms from interacting with other substances. react. In addition, the fluorine-carbon bond has a very high bond energy of 466KJ/mol, which is the highest among all chemical single bonds, so the stability of PTFE is very high.
Application
Chemical field
PTFE neither dissolves nor swells in any known liquid, so PTFE parts will not change in size no matter how long they are used in any corrosive medium. Large thin-walled containers made of PTFE are widely used in the actual operation of laboratories and factories using corrosive liquids. In addition, it is also widely used in seals, pipe linings, pumps, valves, etc.
Mechanical field
No matter what kind of mechanical equipment, the mutual sliding surfaces need to be lubricated during operation to reduce the friction factor, reduce the wear and heat of the parts, and ensure the normal operation ability, precision and power consumption of the mechanical equipment. PTFE's low coefficient of friction and self-lubricating properties make it widely used in the manufacture of bearings, piston rings, machine tool guide rails and sealing materials. However, due to its high cost, it is usually used in precision instruments or environments that require acid and alkali resistance.
Electrical field
PTFE has excellent dielectric properties that are practically independent of temperature and frequency, and at the same time has extremely high thermal stability, so it has become an irreplaceable electrical insulation material, especially in high frequency, high temperature and humid environments middle.
Various forms of PTFE materials play an important role in the field of electrical and electronic insulation today. PTFE glass varnish and glass cloth are used to make high-temperature and high-frequency insulating materials, which can be used in satellite communications and computers; PTFE films are used to make capacitors, as insulating layers, gaskets, cables, etc. between instruments; PTFE thin films of different diameters The wall pipes are respectively used for the lead wire casing, the heat shrinkable pipe and the spiral pipe, the insulating water pipe of the generator, etc.
Construction field
PTFE membrane structure is a new form of architectural structure, which integrates architecture, structural mechanics, fine chemical industry, material science and computer technology, and has a high technical content.
By coating PTFE resin on the ultra-fine glass fiber fabric, the PTFE membrane material is light in weight, high in strength, fire-resistant and flame-retardant, good in self-cleaning property, not affected by ultraviolet rays, fatigue-resistant, twist-resistant, aging-resistant, and has a long service life. Light transmittance, low heat absorption characteristics. It is precisely because of the invention of this cross-age membrane material that the membrane structure building has become a modern permanent building.
Medical field
PTFE is water-resistant, physiologically inert and non-sticky, so it is used in many tissue repair materials and artificial organ materials, such as artificial blood vessels, heart repair membranes, etc. Moreover, the biggest advantage of PTFE is that it can be sterilized by any method, and it will not be denatured by high-pressure heating or treatment with various disinfectants. Therefore, it is widely used in medical devices such as sutures, disinfection pads, and injection needles.
