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Preparation method of polyvinylidene fluoride modified film

A polyvinylidene fluoride modification technology, which is applied in the field of preparation of polyvinylidene fluoride modified membranes, can solve the problems of difficult large-scale practical application, many equipment and raw materials, and complicated process, so as to achieve easy engineering, The effect of cheap PAN raw materials and simple process equipment

Inactive Publication Date: 2010-11-10
TIANJIN POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But the technological process of above-mentioned method is more complicated, and required equipment and raw material are more, and cost is high, is not easy to large-scale practical application

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Configure the casting solution: mix the PVDF / PAN blend with a mass concentration (the same below) of 20% (the mass concentration of PVDF is 14%; the mass concentration of PAN is 6%) and the polyethylene glycol with a mass concentration (the same below) of 12%. After mixing alcohol 400, dissolve in dimethylacetamide solvent with a mass concentration of 68%, stir at 70°C until completely dissolved, and defoam in a vacuum oven at 70°C to obtain a clear casting solution.

[0033] Membrane production: Scrape the casting solution to form a flat membrane, and immediately immerse it in ultrafiltration water at room temperature, and wait for 24 hours for the membrane to solidify and form.

[0034] Hydrolysis modification: Hydrolyze in 50°C, 8wt% sodium hydroxide solution for 1 hour to obtain the PVDF modified membrane of the present invention.

[0035] Performance test: Clean the residual lye on the membrane, and the obtained PVDF modified membrane filters acid solutions with pH...

Embodiment 2

[0037] As described in Example 1, under the condition of other conditions unchanged, the hydrolysis condition was changed to hydrolysis in 40% sulfuric acid solution at 80° C. for 4 hours.

[0038] Performance test: Clean the residual acid solution on the membrane, and the obtained PVDF modified membrane filters acid solutions with pH values ​​of 2 and 4; pure water with pH values ​​of 7; alkaline solutions with pH values ​​of 10 and 12, and measure their water flux . The resulting membrane flux (L / m 2 h) are 55.67; 48.72; 45.34; 30.05; 20.18, respectively. The results showed that the water flux of the obtained PVDF modified membrane showed obvious responsiveness with the change of pH value.

Embodiment 3

[0040] The mass ratio of the two in the PVDF / PAN blend described in Example 1 is changed to PVDF mass concentration as 18%, PAN mass concentration as 2%, polyethylene glycol 400 as 4%, dimethylacetamide content Determined as 76%, other conditions unchanged, hydrolyzed in 50 ℃, 10wt% sodium hydroxide solution for 2 hours, the remainder is the same as in Example 1.

[0041] Performance test: Clean the residual lye on the membrane, and the obtained PVDF modified membrane filters acid solutions with pH values ​​of 2 and 4; pure water with pH values ​​of 7; alkaline solutions with pH values ​​of 10 and 12, and measure their water flux . The resulting membrane flux (L / m 2 h) 6.04, 12.5, 21.46, 14.38, 11.96, respectively. The results showed that the water flux of the obtained PVDF modified membrane showed obvious responsiveness with the change of pH value.

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PUM

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Abstract

The invention discloses a preparation method of polyvinylidene fluoride modified film, which has the technique comprising the following steps of: 1. designing the following components of casting film liquid by weight percent: 14-18% of PVDF, 2-6% of PAN, 4-12% of pore-forming agent and 68-76% of solvent, wherein the pore-forming agent is soluble polymer including polyethylene glycol, and the solvent is good solvent of PVDF and PAN and comprises dimethyl acetyl amide, dimethyl formamide or dimethyl sulfoxide; stirring the components in water bath at 60-70 DEG C for 3-4h, carrying out vacuum defoamation, and obtaining the casting film liquid; 2. manufacturing the casting film liquid into a flat-plat film at the room temperature, then immediately dipping into coagulating bath, maintaining for 24h and curing for molding; and 3. putting the flat-plat film into sodium hydroxide solution with the mass concentration of 8-12%, and treating at 50-60 DEG C for 1-2h; or putting the flat-plat film into sulfuric acid solution with the mass concentration of 40-50%, and treating at 80-100 DEG C for 3-4h; and then, washing the film until neutrality, and obtaining the polyvinylidene fluoride modified film.

Description

technical field [0001] The invention relates to a film preparation technology, in particular to a preparation method of a polyvinylidene fluoride modified film with pH value response behavior. Background technique [0002] Polyvinylidene fluoride (PVDF) has good mechanical strength, chemical stability, heat resistance, weather resistance, anti-ultraviolet and anti-microbial erosion properties, and is a commonly used membrane material. However, the hydrophobicity of PVDF makes its membrane easy to foul, so that the water flux of the membrane decreases and is not easy to recover. This defect seriously restricts the application prospect of PVDF membrane. The solution is to use a blending method to improve the performance of PVDF membrane materials, which can avoid the shortcomings of a single component and prepare a blended membrane with different polymer properties. [0003] The pH sensitive membrane is a PVDF modified membrane. It senses, responds to and adjusts its fun...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/34
Inventor 肖长发张旭良胡晓宇
Owner TIANJIN POLYTECHNIC UNIV
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