Gas-liquid displacement method of pore size analyzer - Database & Sql Blog Articles

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Fundamental:
Taking a certain membrane material as an example, the membrane is sufficiently wetted with a liquid that can be infiltrated with it, and the infiltrating liquid is bound to the pores of the membrane due to the presence of surface tension; a gradually increasing gas pressure is applied to one side of the membrane, When the gas pressure reaches a pressure greater than the surface tension of the immersion liquid in a certain pore size, the immersion liquid in the pore size will be pushed out by the gas; since the pore diameter is smaller, the pressure generated by the surface tension is higher, so the immersion liquid is introduced therein. The gas pressure to be applied is also higher; similarly, it can be seen that the immersion liquid in the pores of the pores will be first pushed out to allow gas to permeate, and then as the pressure increases, the pore size is large to small, and the immersion liquid in the pores Pushed in sequence to allow gas to pass through until all the holes are opened to achieve the same transmittance as the dry film;

The pressure corresponding to the first opened hole is the bubble point pressure, and the aperture corresponding to the pressure is the aperture; in this process, the pressure and flow rate are recorded in real time to obtain the pressure-flow curve; the pressure reaction pore size information, the flow response Information on the number of holes in a certain aperture; then the pressure-flow curve of the dry film is tested, and the pore size, average pore size, minimum pore size, pore size distribution, and transmittance of the film sample can be calculated according to the corresponding formula.
The relationship between pore size and pressure is like the Washburn formula:
D=4γCosθ/p
In the formula, D = pore diameter γ = surface tension of liquid θ = contact angle and p = percentage of flow rate of pressure difference pore size distribution:
f(D)=-d[Fw/Fd)x100]/dD
In the formula, Fw is the wet sample flow rate, and Fd is the dry sample flow rate.