Why is the corrosion resistance of PTFE (Teflon) so good


Polytetrafluoroethylene is one of the fluoroplastics us […]

Polytetrafluoroethylene is one of the fluoroplastics used for sealing. It has the characteristics of high corrosion resistance, high and low-temperature resistance, and stable physical properties. Its corrosion resistance even exceeds that of stainless steel, gold, platinum, and ceramics. It is known as the "Plastic King". Products such as polytetrafluoroethylene sealing ring, polytetrafluoroethylene film, polytetrafluoroethylene pipe products, etc., are widely praised in the market.
Why is PTFE so good in corrosion resistance? Let's take a look at its simple structure: -[-CF2-CF2-]n-. The CF covalent bond determines its superiority in corrosion resistance. Some reactions such as oxidation and chlorination cannot cause damage to the CF covalent bond. Because the CC covalent bond is usually protected by the CF covalent bond, that is to say, other It is difficult for atoms to get close to the electron cloud between the CC bonds and is repelled by the electronegativity of the F atom. Therefore, PTFE does not follow most of the known strong chemical reagents, such as strong acids and bases, water, and various organic solvents. Reaction, its corrosion resistance is self-evident.
Polytetrafluoroethylene (PTFE) has excellent chemical stability, can withstand all strong acids, strong alkalis, and strong oxidants, and does not interact with various organic solvents. PTFE has a wide operating temperature range. It can be used for a long time at -180°C~250°C under normal pressure. After 1000 hours of treatment at 250°C, its mechanical properties have little change. PTFE has a very low friction factor, is a good anti-friction, self-lubricating material, its static friction coefficient is less than the dynamic friction coefficient, so it has the advantages of low starting resistance and smooth running when used to make bearings. Because PTFE is non-polar, heat-resistant and does not absorb water, it is also an excellent electrical insulating material. It also has excellent aging resistance, non-stickiness, and non-combustibility.
Polytetrafluoroethylene is the main force of corrosion-resistant materials on the market. With its excellent corrosion resistance, it has become the main corrosion-resistant material in petroleum, chemical, textile, and other industries. Its specific applications include: conveying corrosive gas pipelines, exhaust Gas pipes, steam pipes, high-pressure oil pipes, aircraft hydraulic systems and low-pressure pipes, distillation towers, heat exchangers, kettles, towers, tank linings, valves and other chemical equipment. Various profiles and parts made of PTFE, such as bars, pipes, films, bearings, gaskets, valves, etc., are widely used in machinery, chemical industry, aviation, electrical and electronics, defense industry, cutting-edge technology, medical and health, and electrical insulation And other fields.