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Polyvinylidene fluoride/liquid crystal blending microporous membrane and preparation method thereof

A polyvinylidene fluoride, microporous membrane technology, applied in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc., can solve the problems of insignificant increase in membrane flux, inability to obtain modification effects, and increase in manufacturing costs. , to achieve the effect of improving mechanical strength and hydrophilicity, high modulus, and reducing membrane cost

Inactive Publication Date: 2011-05-04
TIANJIN POLYTECHNIC UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these modification methods have certain defects: for example, the method of coating the surface of the membrane with specific substances to modify the surface of the PVDF membrane, the biggest problem of this method is that the receiving or block copolymer added or coated is easy to Detach from the PVDF membrane surface, can not obtain permanent modification effect; another example, the modification method of plasma or radiation grafting on the PVDF membrane surface, due to the cross-linking of macromolecules on the membrane surface, the thermal stability of PVDF membrane is limited. The decrease, and a longer post-coagulation process is required after grafting, which increases the manufacturing cost of the membrane
The film-making conditions described in this document require too high temperature, but the increase in membrane flux is not obvious, and it does not involve the influence of liquid crystal mixing on the mechanical strength of the membrane.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] 1. Dissolve 45 (wt)% cyanoethyl cellulose in 55 (wt)% glacial acetic acid, keep the temperature at 50°C for 12h, and then let stand at room temperature for 72h to form a lyotropic liquid crystal;

[0038] 2. Weigh polyvinylidene fluoride by mass percentage: 15 (wt)%; polymer lyotropic liquid crystal: 0.4 (wt)%; N,N-dimethylformamide: 79.6 (wt)%; anhydrous chlorine Lithium chloride: 5(wt)%;

[0039] 3. Add the organic solvent, PVDF, and additives into the three-necked flask in sequence, and stir for 6 hours at 60°C at a rate of 200r / min until the mixture is uniform, then add the lyotropic liquid crystal in the stated proportion, and at 80°C, After stirring at a rate of 600r / min for 8 hours, vacuum degassing at 60°C to make a casting solution;

[0040] 4. Spin hollow fiber membranes using traditional techniques and equipment, and then carry out solid / liquid (S / L) phase separation in a coagulation bath to obtain polyvinylidene fluoride / liquid crystal blended microporous m...

Embodiment 2

[0044] 1. Dissolve 37.5 (wt)% cyanoethyl cellulose in 62.5 (wt)% acrylic acid, keep the temperature at 50°C for 12h, and then let it stand at room temperature for 72h to form a lyotropic liquid crystal;

[0045] 2. Weigh polyvinylidene fluoride by mass percentage: 10 (wt)%; polymer lyotropic liquid crystal: 0.4 (wt)%; N,N-dimethylacetamide: 79.6 (wt)%; anhydrous chlorine Lithium chloride: 10(wt)%;

[0046] 3. Add the organic solvent, PVDF, and additives into the three-necked flask in turn, and stir for 4 hours at 60°C at a rate of 200r / min until the mixture is uniform, then add the lyotropic liquid crystal in the stated proportion, and at 80°C, After stirring at a rate of 400r / min for 8h, vacuum degassing at 60°C to make a casting solution;

[0047] 4. Spin hollow fiber membranes using traditional techniques and equipment, and then carry out solid / liquid (S / L) phase separation in a coagulation bath to obtain polyvinylidene fluoride / liquid crystal blended microporous membranes...

Embodiment 3

[0051] 1. Dissolve 28 (wt)% cyanoethyl cellulose in 72 (wt)% N,N-dimethylformamide, keep the temperature at 50°C for 12h, and then let it stand at room temperature for 72h to form a lyotropic liquid crystal;

[0052] 2. Weigh polyvinylidene fluoride by mass percentage: 30 (wt)%; polymer lyotropic liquid crystal: 0.4 (wt)%; N, N-dimethyl sulfoxide: 59.6 (wt)%; anhydrous chlorine Lithium chloride: 3(wt)%, polyethylene glycol 600: 7(wt)%;

[0053] 3. Add the organic solvent, PVDF, and additives into the three-necked flask in turn, and stir at 80°C for 12 hours at a rate of 200r / min until the mixture is uniform, then add the lyotropic liquid crystal in the stated proportion, and After stirring at a rate of 800r / min for 12h, vacuum degassing at 60°C to make a casting solution;

[0054] 4. Spin hollow fiber membranes using traditional techniques and equipment, and then carry out solid / liquid (S / L) phase separation in a coagulation bath to obtain polyvinylidene fluoride / liquid crys...

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Abstract

The invention discloses a polyvinylidene fluoride / liquid crystal blending microporous membrane and a preparation method thereof. The microporous membrane comprises the following components by mass percentage (wt%):10-30% of polyvinylidene fluoride, 0.4-4% of macromolecule lyotropic liquid crystal, 56-88.6% of organic solvent and 1-10% of additive. The preparation method comprises the following components of the microporous membrane by mass percentage (wt%) and the following steps: (1) 25-27% of cyanoethyl cellulose or cyanoethyl-ethyl cellulose is dissolved into 25-75% of N,N-dimethyl fomamide, N,N-dimethyl acetamide, N,N-dimethyl sulfoxide, glacial acetic acid or crylic acid, is put in constant temperature of 50 DEG C for 12 hours, and is stood for 72 hours at room temperature to form lyotropic liquid crystal; (2) microporous membrane components are weighted; (3) the organic solvent, polyvinylidene fluoride and additive are evenly mixed, and then the lyotropic liquid crystal is addedto form membrane forming liquid; (4) the traditional technology and devices are used for weaving a hollow-fibre membrane or a striking flat membrane; and (5) the obtained microporous membrane is dipped in protection liquid for 3-24 hours to obtain the microporous membrane of the invention.

Description

technical field [0001] The invention relates to polymer organic membrane technology, in particular to a polyvinylidene fluoride / liquid crystal blended microporous membrane used in water treatment and chemical separation processes and a preparation method thereof. Background technique [0002] Separation membrane has the functions of separation, concentration, purification and refining, and has the characteristics of high efficiency, energy saving, environmental protection, molecular level filtration, simple process and easy automatic control. It is the preferred technology for drinking water treatment in the 21st century. Membrane is the core of membrane technology, and the chemical properties and membrane structure of membrane materials play a decisive role in the membrane separation process. Polyvinylidene fluoride (PVDF) has the advantages of good heat resistance, chemical stability and radiation resistance. Therefore, PVDF is favored by people as a membrane material, es...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D71/34
Inventor 张宇峰刘佳武长城张宏伟王亮田林
Owner TIANJIN POLYTECHNIC UNIV
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