Raw material belt

Update:22-08-2018
Summary:

The raw material chemical name is Teflon [1], ordinary […]

The raw material chemical name is Teflon [1], ordinary white polytetrafluoroethylene tape is commonly used in HVAC and water supply and drainage, and natural gas pipelines also have special Teflon tape. In fact, the main raw materials are polytetrafluoroethylene. Vinyl fluoride, but some processes are different.
Raw material belt is made of imported materials and advanced technology. It has excellent quality and complete specifications to meet the requirements of different customers in different industries. The product has extremely superior insulation, strong chemical stability and good sealing performance, and is widely used in various fields such as machinery, chemical industry, metallurgy, electric power, shipbuilding, aerospace, medicine, electronics and so on.
definition
The raw material belt is also called PTFE strip, and the polytetrafluoroethylene is a polymer of tetrafluoroethylene, which is abbreviated as PTFE.
basic structure
The basic structure of polytetrafluoroethylene is - CF2 - CF2 - CF2 - CF2 - CF2 - CF2 - CF2 - CF2 - CF2 - CF2 -.
Molecular weight
The relative molecular mass of PTFE is relatively large, low in the hundreds of thousands, high in more than 10 million, generally in the millions (degree of polymerization in the order of 104, and polyethylene in only 103). The crystallinity is generally 90 to 95%, and the melting temperature is 327 to 342 °C. The CF2 units in the PTFE molecule are arranged in a zigzag shape. Since the radius of the fluorine atom is slightly larger than that of hydrogen, the adjacent CF2 units cannot be completely cross-oriented, but form a helical twisted chain, and the fluorine atoms are almost covered. 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 untwisted to form a 15/7 helix.
Although the cleavage of carbon-carbon bonds and carbon-fluorine bonds in perfluorocarbons requires energy absorption of 346.94 and 484.88 kJ/mol, respectively, the depolymerization of polytetrafluoroethylene to produce 1 mol of tetrafluoroethylene requires only 171.38 kJ of energy. Therefore, at the time of pyrolysis, the polytetrafluoroethylene is mainly depolymerized into tetrafluoroethylene. The weight loss rate (%) of polytetrafluoroethylene at 260, 370 and 420 ° C was 1 × 10 -4 , 4 × 10 - 3 and 9 × 10 - 2 , respectively. It can be seen that polytetrafluoroethylene can be used at 260 ° C for a long time. Due to the highly toxic by-products such as fluorophosgene and perfluoroisobutylene, it is necessary to pay special attention to safety protection and prevent PTFE from contacting open flames.
Performance
Polytetrafluoroethylene (F4, PTFE) has a series of excellent performance: high temperature resistance - long-term use temperature of 200 ~ 260 degrees, low temperature resistance - still soft at -100 degrees; corrosion resistance - resistant to aqua regia and all organic solvents; Weather resistance - extremely long aging life in plastics; high lubrication - very small friction coefficient in plastics (0.04); non-sticky - with minimal surface tension in solid materials without adhering to any substance; non-toxic - physiological Inert; excellent electrical properties, ideal for Class C insulation. PTFE materials are widely used in important departments such as defense industry, atomic energy, petroleum, radio, electric machinery, and chemical industry.