Method for determining porosity of polymer porous plate-type membrane material

Abstract

The invention discloses a method for determining porosity of a polymer porous plate-type membrane material. The method comprises the following steps: adding the polymer porous plate-type membrane material to be tested in a plate-type membrane soaking component, enabling water to pass through the membrane material to be tested for 5-60min at the pressure of 0.01-0.5MPa, filling the membrane pores with water fully, taking the membrane material to be tested out of the component, suspending the membrane material to be tested on a hook of a density balance and soaking the membrane material in water, obtaining the mass Wa of the membrane material to be tested by measurement, then taking the membrane material to be tested out of the water, wiping the surface of the membrane to dry by cloth full of water, obtaining the mass Wb of the membrane material in air by measurement, later drying the membrane material to be tested to constant weight in air, obtaining the mass Wc of the membrane material in air by measurement, and finally carrying out calculation according to a formula: epsilon=(Wb-Wc) / (Wb-Wa), thus obtaining the porosity of the membrane material. By the method for determining the porosity of the polymer porous plate-type membrane material, the influence of a high-temperature boiling process in the traditional soaking method on the pore structure of a polymer is avoided and the method has the characteristics of simple technology and correct determination result.

Description

technical field [0001] The invention relates to a method for measuring the porosity of a polymer porous plate membrane material by using an improved infiltration method. Background technique [0002] The porosity of the polymer is the ratio of the total micropore volume of the polymer membrane to the total volume of the membrane, and it is an important parameter to measure the flux of the membrane. This is because for polymer membranes with approximately the same pore size, the larger the porosity, the more micropores per unit area, and the greater the fluid flux under the same pressure; otherwise, the smaller the flux, the membrane The porosity is of great significance in membrane characterization. [0003] At present, there are mainly three methods for testing the porosity of polymer membranes, namely direct observation by electron microscope, carbon tetrachloride adsorption method, and dry film-wet film infiltration method. [0004] Electron microscopy direct observatio...

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Problems solved by technology

However, it is well known that the pore structure of the polymer membrane will inevitably change during the high temperature boiling process, which will affect the determination of the real porosity of the membrane, so the result of the dry film-wet membrane infiltration method to measure the porosity of the polymer membrane is not accurate enough.

[0007] The dry and wet film weight method can also determine the porosity of polymer film materials. It is a simplified water absorption method. First, the mass W of the dry film is determined. 1 , and then immerse the dry film in a liquid that can wet the film material (its density is ρ 液 ), take it out, dry it and weigh it to get W 2 , and then according to ε=(W 2 -W 1 ) / ρ 液 V calculates the porosity, but the volume V of the membrane in this calculation method is not easy to measure accurately, so there are also errors

[0008] In addition, the method of measuring the porosity of the membrane material is the mercury intrusion method. [12] , volume weight method [13] etc., but the process of measuring membrane porosity by mercury intrusion porosimetry is slightly complicated, and the volumetric gravimetric method can only obtain the total porosity of the membrane, and cannot reflect the open porosity of the membrane, so these two methods also have their own shortcomings

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