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Method for preparing nonpolar polyvinylidene fluoride ultrafiltration membrane

A polyvinylidene fluoride and ultrafiltration membrane technology, which is applied in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc., to achieve the effects of less interference, stable film-forming performance, and reduced production costs

Active Publication Date: 2014-03-12
XIAMEN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

There are few reports on the targeted preparation of non-polar PVDF porous membranes dominated by α crystals

Method used

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  • Method for preparing nonpolar polyvinylidene fluoride ultrafiltration membrane
  • Method for preparing nonpolar polyvinylidene fluoride ultrafiltration membrane
  • Method for preparing nonpolar polyvinylidene fluoride ultrafiltration membrane

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] PVDF (viscosity average molecular weight M v =345,000g / mol, the smaller molecular weight can accelerate the stable formation of the crystal form) and ethanol are dissolved in a mixture of dimethylacetamide (DMAC) and acetone at 60°C, and the mass percentage of raw materials is PVDF: DMAC : Acetone: Ethanol = 12: 24: 62: 2, stir until PVDF is completely dissolved, let it stand for defoaming, scrape it on a clean and flat glass plate with a scraper, and expose it to air for 2 hours (volatile solvent is good for non-polar conformation Formation). Immerse the scraped film solution in the first gel bath for 10 minutes, the temperature of the first gel bath is 40°C, and the high temperature accelerates the formation of α crystal form, the composition of the first gel bath is: the mass percentage concentration is 50% octane Aqueous solution of alcohol to get nascent film. The nascent membrane was then immersed in a second gel bath containing only deionized water at 40°C for ...

Embodiment 2

[0038] PVDF (viscosity average molecular weight M v =254,000g / mol) and ethanol are dissolved in dimethylformamide (DMF) at 80°C, the mass ratio of raw materials is PVDF:DMF:ethanol=15:82:3, stir until PVDF is completely dissolved, and let stand After defoaming, scrape it on a clean and flat glass plate with a scraper, and expose it to the air for 1 hour to evaporate. Immerse the scraped film solution in the first gel bath for 20 minutes, the temperature of the first gel bath is 40°C, the composition of the first gel bath is: an aqueous solution with a mass percentage concentration of 50% methanol to obtain a nascent film . The nascent membrane was then immersed in a second gel bath containing only deionized water at 20°C for 24 hours. Finally, the membrane was immersed in the third gel bath: an aqueous solution with a mass percent concentration of 10% ethanol for 24 hours. Dry the rinsed membrane at 20°C to obtain an ultrafiltration membrane with a certain crystal conforma...

Embodiment 3

[0043] PVDF (viscosity average molecular weight M v=431,000g / mol) and LiCl are dissolved in dimethylacetamide (DMAC) at 80°C, the mass ratio of raw materials is PVDF:DMAC:LiCl=15:83:2, stir until PVDF is completely dissolved, and let stand After degassing, scrape it on a clean and flat glass plate with a scraper, and expose it to the air for 2 hours to evaporate. Immerse the scraped film solution in the first gel bath for 30 minutes, the temperature of the first gel bath is 60°C, the composition of the first gel bath is: the mass percentage concentration is 10% propanol (mass percentage concentration can also be used Replaced by 10% isopropanol) in aqueous solution to obtain nascent membranes. The nascent membrane was then immersed in a second gel bath containing only deionized water at 30°C for 24 hours. Finally, the membrane was immersed in the third gel bath: an aqueous solution with a mass percent concentration of 20% glycerol for 24 hours. Dry the rinsed membrane at 30...

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Abstract

The invention discloses a method for preparing a nonpolar polyvinylidene fluoride ultrafiltration membrane. The method comprises the following steps: (1) mixing raw materials, evenly agitating at 40-80 DEG C, standing and defoaming to obtain polyvinylidene fluoride membrane liquid, and standing for later use; (2) scraping the membrane liquid on a clean and smooth glass plate, exposing in air to volatize solvent for 0.5-24 hours, wherein the thickness of the membrane liquid is 120-600 microns; (3) immersing the scraped membrane liquid into a first coagulation bath alcohol-water solution, and soaking for 0.02-72 hours under the condition at 40-80 DEG C, so as to prepare a coarse ecological membrane; (4) immersing the coarse ecological membrane into a second coagulation bath, and soaking for 24-72 hours under the condition at 0-80 DEG C; (5) immersing the membrane into a third coagulation bath alcohol-water solution for 2-24 hours, and airing under the condition at 20-50 DEG C, so as to obtain the nonpolar polyvinylidene fluoride ultrafiltration membrane with stable performance. The preparation method disclosed by the invention is simple in technology, and low in production cost; the prepared polyvinylidene fluoride ultrafiltration membrane is non-polar, strong in mechanical strength, good in hydrophilicity, and strong in anti-pollution capacity.

Description

technical field [0001] The invention relates to a preparation method of a polyvinylidene fluoride ultrafiltration membrane, in particular to a method for preparing a non-polar polyvinylidene fluoride ultrafiltration membrane by changing the components of the casting liquid and the parameters of the membrane making process through a phase inversion method. Background technique [0002] Polyvinylidene fluoride (PVDF) is a semi-crystalline polymer with excellent chemical stability, thermal stability and physical strength. This is because PVDF has a special molecular structure, the simplified formula is: —[CH 2 —CF 2 ]n—, the almost gap-free space barrier formed by F atoms makes it impossible for any atom or group to enter the interior of its structure and destroy the carbon chain. [0003] In view of the above advantages of PVDF, and it can be cast into films with better performance, several famous membrane companies such as Millipore, Pall, Koch Membrane System, etc. have re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/34B01D69/02B01D67/00
Inventor 叶茜严滨刘斌刘美兰廖文超
Owner XIAMEN UNIV OF TECH
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