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Polyvinylidene fluoride film hydrophilically modified method

A polyvinylidene fluoride membrane, polyvinylidene fluoride technology, applied in the field of modification of membrane products, can solve problems such as unseen, decline, shortening of membrane service life, etc., to facilitate industrial application, enrich pore structure, improve affinity water-based effect

Inactive Publication Date: 2008-03-26
TIANJIN POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, its strong hydrophobicity will lead to two problems: one is that the separation process requires a large driving force; the other is that it is easy to generate adsorption pollution, which will reduce the two main separation indicators of membrane flux and rejection rate, and shorten the service life of the membrane. Restricts its application in water phase systems such as biochemical pharmaceuticals, food and beverage, and water purification
The above technical literature only discusses the effect on membrane performance from the perspective of hydrophilicity, while ignoring the influence of interface pore structure on membrane performance
[0005] Polyvinyl alcohol is a good hydrophilic polymer. It is used as a blending component to improve the interfacial pore structure of polyvinylidene fluoride membranes and combined with hydrophilic modification. There has been no report so far.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037]Mix polyvinylidene fluoride / polyvinyl alcohol with a mass concentration ratio of 20% and dimethyl sulfoxide with a mass concentration ratio of 80%; place the above mixture in a water bath at 98°C, stir for 6 hours, and let it stand Degassing to obtain a uniform casting solution; after scraping the casting solution with a glass plate at room temperature to make a flat film, immediately immerse it in 20°C and 20% alcohol aqueous solution to solidify and form; after the film falls off by itself, take out the glass plate , the film was kept in the coagulation bath for 24 hours; after the formed flat film was rinsed with water, soaked in a 60% glycerin aqueous solution for 12 hours, it was taken out and dried naturally in the air to make PVDF with good hydrophilicity. flat film.

[0038] The mass ratios of polyvinylidene fluoride / polyvinyl alcohol described in the above method are respectively 100 / 0, 90 / 10, 80 / 20, 70 / 30, 50 / 50, 0 / 100, and the scraped flat film is heated at 20...

Embodiment 2

[0041] Prepare the casting solution according to the method described in Example 1; after the casting solution is scraped with a glass plate at room temperature to make a flat film, place it in the air at 20°C to solidify and form, and use the solvent evaporation method to make the film, which can avoid the surface micropore docking The influence of tentacles; after forming, immerse in clean water, and after the film falls off by itself, take out the glass plate, and keep the film in clean water for 24 hours; take it out and dry it naturally in the air. The contact angles of the upper surface and the lower surface of the flat film made by measuring the mass ratio of polyvinylidene fluoride / polyvinyl alcohol as 100 / 0, 90 / 10, 80 / 20, 70 / 30, 50 / 50, and 0 / 100 were respectively determined. The corresponding values ​​of contact angles (°) on the upper surface of the film were 98.2, 96.8, 92.1, 71.2, 67.3, 38.7; The results show that when the mass ratio of polyvinylidene fluoride / poly...

Embodiment 3

[0043] Mix polyvinylidene fluoride / polyvinyl alcohol (mass ratio 80 / 20) with a mass concentration ratio of 20% and dimethyl sulfoxide with a mass concentration of 80%; mix and defoam the above mixture according to the method in Example 1 Immediately after scraping the film, immerse in the following coagulation bath to solidify and form; after the film falls off automatically, take out the glass plate, and keep the film in the coagulation bath for 24 hours; the formed film is made into a dry film according to the method in Example 1. The coagulation baths are respectively 20°C water, 20°C, 20% alcohol aqueous solution and 20°C, 5mol / L NaCl aqueous solution. Measure the water flux and the retention rate of ovalbumin in the flat membrane prepared in three coagulation baths at 20°C and 0.1Mpa respectively, and the water flux (mL·cm -2 h -1 ) corresponding values ​​were 2.67, 4.13, 2.45; the corresponding values ​​of ovalbumin retention (%) were 80.0, 63.3, 81.0 (%). The results ...

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PUM

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Abstract

The present invention relates to a method for preparing polyvinylidene fluoride membrane with modified hydrophilicity. Said method includes the following steps: (1), membrane-casting liquor preparation: using (by wt%) 10-18% of polyvinylidene fluoride, 2-10% of polyvinyl alcohol and 80% of dimethyl sulfoxide, mixing them to obtain their mixed liquor, placing said mixed liquor in a water bath with 98deg.C, stirring for 6h, then standing still and defoaming so as to obtain uniform membrane-casting liquor; and (2), membrane preparation: under the condition of room temperature utilizing said membrane-casting liquor to prepare plate membrane or utilizing wet process to spin hollow fiber membrane, then promptly soaking the plate membrane or hollow fiber membrane into a coagulation bath, retaining for 24h, then solidifying and forming, washing the formed membrane by using clean water, and soaking the formed membrane in a glycerine aqueous solution whose mass concentration is 60% for 12h, taking out said formed membrane and naturally drying in air so as to obtain the invented polyvinglidene fluoride plate membrane or hollow fiber membrane with good hydrophilicity. The above-mentioned coagulation bath is one kind of water, ethyl alcohol aqueous solution whose mass concentration is 20% or sodium chloride aqueous solution.

Description

technical field [0001] The invention relates to a modification technology of membrane products, specifically a method aimed at improving the hydrophilicity of polyvinylidene fluoride membranes, and the international patent classification number is proposed to be Int.Cl.C08J7 / 12(2006.01)I. Background technique [0002] Polyvinylidene fluoride is a semi-crystalline polymer. Due to its short C-F bond length and strong bond energy (486kJ / mol), it is heat-resistant, corrosion-resistant, radiation-resistant, and has high strength and good toughness. It is the preferred material for preparing membranes. However, its strong hydrophobicity will lead to two problems: one is that the separation process requires a large driving force; the other is that it is easy to generate adsorption pollution, which will reduce the two main separation indicators of membrane flux and rejection rate, and shorten the service life of the membrane. This restricts its application in aqueous systems such a...

Claims

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Application Information

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IPC IPC(8): B01D71/34
Inventor 肖长发李娜娜安树林胡晓宇
Owner TIANJIN POLYTECHNIC UNIV
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