Mechanical properties and chemical properties of PTFE plates

- Sep 27, 2019-

The PTFE plate has good mechanical properties over a wide temperature range (-196~260 °C). One of the characteristics of perfluorocarbon polymers is that perfluorocarbons are brittle at low temperatures.

The tetrafluorocarbon plate has a large molecular weight, a small molecular weight, and a molecular weight of more than 10 million. The chemical properties of the carbon tetrafluoride plate are generally as follows: the number of carriers of the tetrafluoride plate is one million (degree of polymerization is 104, and polyethylene is only 103). The total crystallinity is 90-95 ° C, and the melting temperature is 327-342 ° C. Since the radius of the fluorine atom is slightly larger than the radius of hydrogen, the adjacent CF2 units are not completely cross-oriented, but form a helical twisted chain. The fluorine atom covers almost the entire surface of the polymer chain. This molecular structure explains the various functions of the tetrafluoride plate. 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 loosened to form a 15/7 helix.

Although the energy absorption of the carbon-carbon bond and the carbon-fluorine bond in the perfluorocarbon requires 346.94 and 484.88 kJ/mol, respectively, the depolymerization of the natural 1 mol tetrafluoroethylene PTFE plate requires only 171.38 kJ. PTFE plates are widely used in high-low temperature, corrosion-resistant materials, insulating materials, anti-stick coatings, etc. in the atomic energy, aerospace, electronics, electrical, chemical, machinery, instrumentation, instrumentation, construction, textile, food and other industries. Therefore, tetrafluoroethylene is the main depolymerized polymer of tetrafluoroethylene during high temperature pyrolysis. The weight loss rates (%) at 260 ° C, 370 ° C and 420 ° C were 1 × 10 ~ (-4), 4 × 10 ~ (-3) and 9 × 10 ~ (-2) / h, respectively. The results show that polytetrafluoroethylene can be used for a long time at 260 °C. Fluorine phosgene and perfluoroisobutylene are also produced during pyrolysis, and special attention should be paid to safety protection to prevent PTFE from coming into contact with open flame.