Advantages of Polytetrafluoroethylene (PTFE)
does ptfe tape melt？
High temperature resistance - working temperature up to 250 C.
Low temperature resistance - good mechanical toughness; 5% elongation can be maintained even when the temperature drops to - 196 C.
Corrosion resistance - For most chemicals and solvents, it shows inertia, strong acid and alkali resistance, water and various organic solvents.
Weather resistance - the best aging life of plastics.
High lubrication - the lowest friction coefficient in solid materials.
Non-adherence - is the smallest surface tension in solid materials and does not adhere to any substance.
Non-toxic - physiological inertia, as artificial blood vessels and organs long-term implantation in vivo without adverse reactions.
Polytetrafluoroethylene (PTFE) has a relatively large molecular weight, with a low molecular weight of hundreds of thousands and a high molecular weight of more than 10 million, generally millions (degree of polymerization is 104 orders of magnitude, while polyethylene is only 103). Generally, the crystallinity is 90-95%, and the melting temperature is 327-342 C. CF2 units in polytetrafluoroethylene molecule are arranged in zigzag shape. Because the radius of fluorine atoms is slightly larger than that of hydrogen, the adjacent CF2 units can not be completely trans-oriented, but form a spiral twisted chain. The fluorine atoms almost cover the surface of the whole polymer chain. This molecular structure explains the various properties of PTFE. 13/6 helix is formed when the temperature is lower than 19 C, and 15/7 helix is formed when the molecule is slightly decomposed at 19 C.
Although carbon-carbon bonds and carbon-fluorine bonds in perfluorocarbons need to absorb energy 346.94 and 484.88 kJ/mol respectively, it only takes energy 171.38 kJ to produce 1 mol tetrafluoroethylene by depolymerization of polytetrafluoroethylene. Therefore, PTFE is mainly depolymerized into tetrafluoroethylene during pyrolysis at high temperature. The weightlessness rates (%) of PTFE at 260, 370 and 420 (%) were 1 *10-4, 4 *10-3 and 9 *10-2 per hour, respectively. It can be seen that PTFE can be used for a long time at 260 C. Due to the toxic by-products such as fluorophosgene and perfluoroisobutylene produced during pyrolysis at high temperature, special attention should be paid to safety protection and prevention of PTFE from exposure to open fire.
The friction coefficient of mechanical properties is only 1/5 of that of polyethylene, which is an important feature of perfluorocarbon surface. Because the interaction force between fluorine and carbon chain is very low, PTFE is not viscous.
It does not melt at 250 C and does not brittle at - 260 C. Polytetrafluoroethylene (PTFE) is so smooth that even ice can't match it; its insulation performance is very good, and a thick film of newspaper can withstand 1500V high voltage.
Polytetrafluoroethylene (PTFE) maintains excellent mechanical properties in a wide range of temperatures ranging from - 196 to 260 C. One of the characteristics of perfluorocarbon polymers is that they are not brittle at low temperatures.
Chemical corrosion resistance and weatherability Polytetrafluoroethylene (PTFE) is hardly corroded by any chemical reagent except molten alkali metal. For example, in concentrated sulphuric acid, nitric acid, hydrochloric acid, or even boiling in aqua regia, the weight and performance of the product remain unchanged, and it is almost insoluble in all solvents, only slightly soluble in total alkanes (about 0.1g/100g) above 300 (?) Polytetrafluoroethylene (PTFE) has excellent weatherability because of its non-moisture absorption, non-flammability, extremely stable to oxygen and ultraviolet radiation.
The dielectric constant and dielectric loss of PTFE in a wide frequency range are very low, and the breakdown voltage, volume resistivity and arc resistance are high.
The radiation resistance of PTFE is poor (104 rad). The degradation of PTFE is caused by high energy radiation. The electrical and mechanical properties of PTFE decrease obviously.
Polytetrafluoroethylene (PTFE) is produced by free radical polymerization of PTFE. Polymerization in industry is carried out by stirring in the presence of a large amount of water to disperse reaction heat and to facilitate temperature control. Polymerization is generally carried out at 40-80 C, 3-26 kgr/cm 2 pressure. Inorganic persulfate and organic peroxide can be used as initiators, and redox initiator system can also be used. 171.38 kJ is exothermic per mole of tetrafluoroethylene. Perfluorinated surfactants, such as perfluorooctanoic acid or its salts, should be added to dispersion polymerization.
Polytetrafluoroethylene (PTFE) can be processed by compression or extrusion. It can also be made into water dispersions for coating, impregnation or fibers. Polytetrafluoroethylene (PTFE) is widely used in the industries of atomic energy, aerospace, electronics, electricity, chemical industry, machinery, instruments, instrumentation, construction, textile, food and other industries as high and low temperature resistant, corrosion resistant materials, insulating materials, anti-sticking coatings, etc.