PTFE pipe When the axial direction is subjected to a pressure that is more than it can support, it will suddenly bend like a compression bar or a cylindrical spiral spring and lose the stability of the linear form. This is certain.
teflon How much pressure can the tube withstand?
If the internal pressure of the PTFE tube exceeds a certain pressure value that it can support, instability will also occur. Experiments have proved that the destruction of high-pressure hose in engineering is mostly caused by this reason. This can happen to both elastic seals, axial expansion compensators and rubber hoses; The ability of PTFE tube to withstand internal pressure generally depends on its stability. To study the stability of high-pressure rubber hose, Euler pressure bar formula can be used to calculate its critical load; Due to the processing deviation of the corrugated geometric size and material thickness, the axis of the PTFE tube often deviates from the original axis of symmetry. That is to say, there is some initial curvature on the axis of the actual high-pressure hose. As for the rubber hose, the uneven knitting of the mesh sleeve and the inconsistent strength of each department also limit the bearing capacity of the high-pressure rubber hose.
The relative molecular weight of polytetrafluoroethylene is relatively large, ranging from hundreds of thousands to tens of millions (polymerization degree is 10 ^ 4, while polyethylene is only 10 ^ 3). The general crystallinity is 90~95%, and the melting temperature is 327~342 ℃. CF2 units in polytetrafluoroethylene molecule are arranged in zigzag shape. Since the radius of fluorine atom is slightly larger than that of hydrogen, adjacent CF2 units cannot be completely trans cross oriented, but form a helical twisted chain, and fluorine atoms almost cover the surface of the entire polymer chain. This molecular structure explains the various properties of PTFE. When the temperature is lower than 19 ℃, 13/6 spiral is formed; The phase transition occurs at 19 ℃, and the molecule slightly unravels to form a 15/7 helix.
