Tianjin Tiansu Binhai Fluorine Plastic Film

Date:2021/7/16 9:18:50 /Read: /Source:本站

Tianjin Tiansu Binhai Fluorine Plastic Film http://www.tjtsjt.net//

Polytetrafluoroethylene is a polymer of tetrafluoroethylene. The English abbreviation is PTFE. The basic structure of polytetrafluoroethylene is.-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2-CF2 -. Polytetrafluoroethylene is widely used in all kinds of anti-acid, alkali and organic solvents. It is not toxic to humans, but perfluorooctanoate (PFOA), one of the raw materials used in the production process, is believed to have carcinogenic effects. http://www.tjtsjt.net//

  The relative molecular mass of polytetrafluoroethylene is relatively large, the low is hundreds of thousands, the high is more than ten million, generally several million (the degree of polymerization is on the order of 104, while polyethylene is only 103). Generally, the crystallinity is 90~95%, and the melting temperature is 327~342℃. The CF2 units in the polytetrafluoroethylene molecule are arranged in a zigzag shape. Because the radius of the fluorine atom is slightly larger than that of hydrogen, the adjacent CF2 units cannot be completely cross-oriented in trans, but form a helical twisted chain, almost covered by the fluorine atom. The surface of the entire polymer chain. This molecular structure explains the various properties of polytetrafluoroethylene. When the temperature is lower than 19°C, a 13/6 helix is formed; at 19°C, a phase change occurs, and the molecules are slightly unwound to form a 15/7 helix. http://www.tjtsjt.net//

  Although the rupture of carbon-carbon bonds and carbon-fluorine bonds in perfluorocarbons requires energy absorption of 346.94 and 484.88kJ/mol, respectively, the depolymerization of PTFE to produce 1mol of tetrafluoroethylene only requires energy of 171.38kJ. Therefore, during high temperature cracking, polytetrafluoroethylene is mainly depolymerized into tetrafluoroethylene. The weight loss rate (%) of PTFE at 260, 370 and 420℃ is 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. As the highly toxic by-products such as fluorophosgene and perfluoroisobutylene are produced during high-temperature cracking, special attention must be paid to safety protection and to prevent PTFE from contacting open flames. http://www.tjtsjt.net//

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