Polytetrafluoroethylene (PTFE) has been widely used in chemical and petroleum industries due to its excellent resistance to high and low humidity, chemical stability, good electrical insulation properties, non-adhesion, weather resistance, flame retardancy and good self-lubricating properties. , textile, electronic and electrical, medical, machinery and other fields have been widely used.
Among fluoroplastics, polytetrafluoroethylene (PTFE) is the most widely consumed and widely used, and is an important variety among fluoroplastics. PTFE has excellent high and low temperature resistance and chemical stability, good electrical insulation properties, non-adhesiveness, weather resistance, flame retardancy and good self-lubricating properties. It is known as the "King of Plastics". This material was first developed for national defense and cutting-edge technology needs, and then gradually extended to civilian use. Its uses involve many aspects of aerospace and civilian use, and it has become an indispensable material in its application fields.
Performance characteristics of PTEE
PTFE is a polymer polymerized from tetrafluoroethylene monomer. It is a transparent or opaque wax similar to PE. Its density is 2.2g/cm3 and its water absorption rate is less than 0.01%. Its chemical structure and limitations Similar, except that all the hydrogen atoms in polyethylene are replaced by fluorine atoms. Due to the high bond energy and stable performance of the C-F bond, it has excellent chemical corrosion resistance and can withstand all strong acids (including dry water), as well as strong oxidants, reducing agents and various organic bath agents: the F atom in the PTFE molecule is symmetrical, the two elements in the C bond are covalently bonded, and there are no free electrons in the molecule, making the entire molecule neutral. property, so it has excellent dielectric properties, and its electrical insulation is not affected by the environment and frequency. Its volume resistance is greater than 1017 kilograms, low dielectric loss, high breakdown voltage, good arc resistance, and can work in an electrical environment of 250°C for a long time; because there are no hydrogen bonds in the PTFE molecular structure, the structure is symmetrical, so its The crystallinity is very high (the crystallinity is 55% to 75%, sometimes as high as 949), which makes PTFE extremely heat-resistant. Its melting temperature is 324°C, its decomposition temperature is 415°C, and its maximum use mixing degree is 250°C. It is brittle. The melting temperature is -190℃, the heat distortion temperature (under the condition of 0.46WPa) is 120℃, the mechanical properties of PTFE are good, its tensile strength is 2128MPa, the bending strength is I14NPa, the elongation half is 250s300%, and the dynamic and static friction of steel The coefficients are both 0.04, which is smaller than the friction coefficients of nylon, polyacetal, and polyester plastics.
Pure PTFE has low strength, poor wear resistance and poor deformation resistance. It is usually necessary to add some inorganic particles to the PTFE polymer, such as graphite, disulfide, sulfide, corrugated fiber, carbon fiber, etc. to improve its mechanical properties: It can also be blended with other polymers such as polyphenyl ester (HIB), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyperfluoro (ethylene/propylene) copolymer (PFEP), etc. Expand its damping temperature range and improve its creep resistance.
PTFE uses
The unique properties of PTFE make it widely used in industrial and marine operations such as chemical industry, stone uranium, textile, food, papermaking, medicine, electronics and machinery.
