Polytetrafluoroethylene bar, tube, plate, turning plate. Polytetrafluoroethylene is a polymer of tetrafluoroethylene. The English abbreviation is PTFE. The structural formula is. It was discovered in the late 1930s and put into industrial production in the 1940s. Properties the relative molecular weight of polytetrafluoroethylene is large, ranging from hundreds of thousands to more than 10 million, generally millions (the degree of polymerization is 104, while that of polyethylene is only 103). The general crystallinity is 90 ~ 95%, and the melting temperature is 327 ~ 342 ℃. CF2 units in polytetrafluoroethylene molecule are arranged in zigzag shape. Because the radius of fluorine atom is slightly larger than that of hydrogen, the adjacent CF2 units cannot be completely trans oriented, but form a helical twisted chain, and the fluorine atom almost covers the surface of the whole polymer chain. This molecular structure explains the various properties of polytetrafluoroethylene. When the temperature is lower than 19 ℃, 13 / 6 helix is formed; Phase transition occurs at 19 ℃, and the molecules are slightly untied to form 15 / 7 spiral polytetrafluoroethylene, which is generally called "non stick coating" or "easy to clean wok material"; It is a synthetic polymer material that uses fluorine to replace all hydrogen atoms in polyethylene. This material has the characteristics of acid resistance, alkali resistance and resistance to various organic solvents, and is almost insoluble in all solvents.
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