The relative molecular mass of PTFE is relatively large, the relative molecular mass of 100,000 is relatively low, up to 10 million, and the total support number of tetrafluorinated plates is one million (degree of polymerization is 10). PTFE sheets 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. 4 orders of magnitude, polyethylene only 10 3). 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 properties of PTFE. When the temperature is lower than 19 ° C, the molecules form a 13/6 helix, a phase transition occurs at 19 ° C, and the molecules are slightly loosened to form a 15/7 helix. Although the carbon-carbon bond and the carbon-fluorine bond in the perfluorocarbon require energy absorption of 346.94 and 484.88 kJ/mol, respectively, only 171.38 kJ of energy can depolymerize the PTFE to produce 1 mol of tetrafluoroethylene. . Therefore, during the pyrolysis process, the PTFE is mainly depolymerized into tetrafluoroethylene. At 260 ° C, 370 ° C and 420 ° C, the weight loss rates (%) were 110-4, 410-3 and 910-2, respectively. The results show that PTFE 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.
PTFE can be compressed or extruded, or it can be made into an aqueous dispersion for coating, impregnation or fiber manufacturing. 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.