CN115337875B - Aerogel and preparation method and application thereof - Google Patents
Aerogel and preparation method and application thereof Download PDFInfo
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- CN115337875B CN115337875B CN202110529317.4A CN202110529317A CN115337875B CN 115337875 B CN115337875 B CN 115337875B CN 202110529317 A CN202110529317 A CN 202110529317A CN 115337875 B CN115337875 B CN 115337875B
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- 239000004964 aerogel Substances 0.000 title claims abstract description 111
- 238000002360 preparation method Methods 0.000 title claims abstract description 27
- 239000004372 Polyvinyl alcohol Substances 0.000 claims abstract description 46
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 46
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 42
- 239000000843 powder Substances 0.000 claims abstract description 40
- 238000010041 electrostatic spinning Methods 0.000 claims abstract description 38
- 239000000835 fiber Substances 0.000 claims abstract description 26
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000002243 precursor Substances 0.000 claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 24
- 239000002270 dispersing agent Substances 0.000 claims abstract description 16
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000002156 mixing Methods 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 238000001132 ultrasonic dispersion Methods 0.000 claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 33
- 238000000034 method Methods 0.000 claims description 23
- 239000002202 Polyethylene glycol Substances 0.000 claims description 14
- 229920001223 polyethylene glycol Polymers 0.000 claims description 14
- 239000007864 aqueous solution Substances 0.000 claims description 12
- 238000000498 ball milling Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 229920002125 Sokalan® Polymers 0.000 claims description 6
- 239000004584 polyacrylic acid Substances 0.000 claims description 6
- 239000004115 Sodium Silicate Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- FQENQNTWSFEDLI-UHFFFAOYSA-J sodium diphosphate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]P([O-])(=O)OP([O-])([O-])=O FQENQNTWSFEDLI-UHFFFAOYSA-J 0.000 claims description 4
- 229940048086 sodium pyrophosphate Drugs 0.000 claims description 4
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 4
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 4
- 235000019818 tetrasodium diphosphate Nutrition 0.000 claims description 4
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 claims description 4
- 239000002904 solvent Substances 0.000 claims description 3
- 238000000227 grinding Methods 0.000 claims description 2
- 238000003801 milling Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 3
- 239000000377 silicon dioxide Substances 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 14
- 239000000499 gel Substances 0.000 description 8
- 238000009413 insulation Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 238000001035 drying Methods 0.000 description 6
- 239000004965 Silica aerogel Substances 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 239000002131 composite material Substances 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 238000001523 electrospinning Methods 0.000 description 4
- 238000003980 solgel method Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- 238000000352 supercritical drying Methods 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000004108 freeze drying Methods 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000012779 reinforcing material Substances 0.000 description 2
- 238000004626 scanning electron microscopy Methods 0.000 description 2
- 239000011240 wet gel Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
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- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 239000007783 nanoporous material Substances 0.000 description 1
- 230000005622 photoelectricity Effects 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
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- 229920003169 water-soluble polymer Polymers 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/0091—Preparation of aerogels, e.g. xerogels
Abstract
The invention provides an aerogel, a preparation method and application thereof, wherein the aerogel has a porous network structure formed by fiber aerogel; the fibrous aerogel material comprises a combination of diatom shells, polyvinyl alcohol, and alumina. The preparation method of the aerogel comprises the following steps: uniformly mixing the diatomite powder, the polyvinyl alcohol solution and the optional water-based dispersing agent, adding aluminum oxide, heating and optionally performing ultrasonic dispersion to obtain an electrostatic spinning precursor solution; and carrying out electrostatic spinning on the electrostatic spinning precursor solution to obtain the aerogel. The aerogel provided by the invention has high porosity, light weight, excellent infrared stealth effect and excellent toughness, and can be used in infrared stealth materials.
Description
Technical Field
The invention belongs to the technical field of nano materials, and particularly relates to aerogel and a preparation method and application thereof.
Background
All objects in nature radiate infrared rays. The amount of the object's ability to radiate infrared is directly related to its surface temperature. Therefore, no matter in daytime or at night, the infrared detector can measure the radiation difference between the target and the background, and infrared images of different objects can be obtained. The existing infrared stealth technical principle is to change the target heat radiation characteristic, but most of stealth materials have the defects of continuous energy consumption, narrow application range, slow reaction and the like.
In recent years, aerogel is widely studied in the fields of heat insulation, energy storage, sound insulation and the like as a nano porous material with a controllable structure. Aerogel production generally consists of a sol-gel process and a supercritical drying process. In the sol-gel process, nanoclusters with different structures are formed in a solution by controlling the hydrolysis and polycondensation reaction conditions of the solution, the clusters are mutually adhered to form gel, and the periphery of a solid framework of the gel is filled with liquid reagents remained after chemical reaction. In order to prevent the damage of the material structure caused by the surface tension in the micropore holes in the gel drying process, a supercritical drying process is adopted for treatment. However, supercritical drying processes have high equipment requirements and are not conducive to large-scale preparation of aerogel products at this stage.
With development of nano technology, electrostatic spinning is a simple and effective novel processing technology, and can play a great role in the fields of biomedical materials, filtration and protection, catalysis, energy sources, photoelectricity, food engineering, cosmetics and the like. Meanwhile, the electrostatic spinning preparation of the fiber aerogel is also a future development trend, and the fiber aerogel will occupy a place in the field of infrared stealth materials.
Because of the nano porous network structure, the silicon dioxide aerogel has the porosity of 80-99.8%, is the material with the best heat insulation performance so far, has wide application prospect in the fields of aerospace, petrochemical industry, electric power metallurgy, building energy conservation, precise instruments and the like, and is a revolutionary substitute product of the traditional heat insulation material. At present, most of the preparation methods of silicon-based aerogel are sol-gel method and post-drying treatment, for example, CN101318659A discloses a method for preparing silicon dioxide aerogel composite material by normal pressure drying, which comprises the following steps: (1) Compounding the silica sol with the reinforcing material, standing to form composite gel, and aging; (2) And performing hydrophobic modification on the aged composite gel by using a modifier, and drying at normal pressure to obtain the silica aerogel composite material. The silica aerogel composite material prepared by the method has extremely low heat conductivity coefficient, greatly improves the added value of reinforcing materials such as fiber bodies, can be widely applied to the heat insulation, heat insulation and sound insulation aspects of building heat insulation, industrial pipeline transportation and the like, and expands the application fields of silica and fiber bodies. CN111039295a discloses a one-step process for preparing silica aerogel, comprising: (1) Mixing and stirring a silicon source precursor A, a silicon source precursor B, a solvent and water to obtain a premixed solution; (2) Mixing a gel catalyst with the premixed solution, and performing a gel reaction to obtain a silica wet gel; (3) And aging and drying the silica wet gel to obtain the silica aerogel. The silica aerogel has good pore structure, large specific surface area and low thermal conductivity. However, the products obtained by the sol-gel process and the post-drying treatment are generally brittle and have a low porosity.
Therefore, it is of great practical importance to study a silica-based aerogel with higher porosity and better toughness.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide aerogel, a preparation method and application thereof, wherein diatom shells are selected as fiber aerogel materials, and the diatom shells are natural porous silica, so that the porosity of the prepared aerogel is up to more than 90 percent due to the porous structure of the silica and the three-dimensional porous structure formed by the fiber aerogel materials, and the aerogel has excellent infrared stealth performance and excellent toughness.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
in a first aspect, the present invention provides an aerogel having a porous network of fibrous aerogel; the fibrous aerogel material comprises a combination of diatom shells, polyvinyl alcohol, and alumina.
The aerogel provided by the invention is silicon-based aerogel, has a porous network structure formed by fiber aerogel, and the fiber material comprises a combination of diatom shells, polyvinyl alcohol and alumina, wherein the diatom shells are natural porous silica, the polyvinyl alcohol is a water-soluble polymer capable of being electrospun, the mixture of the polyvinyl alcohol and the silica can enable the porous silica to be electrospun and molded, and the alumina can provide an acidic environment when added into an aqueous solution, so that the diatom shells are formed by an electrospinning process. Thus, the combination of these three components can produce an air-out gel and give it a higher porosity and better toughness.
In the present invention, the aerogel has a thickness of 0.1 to 2mm, for example, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.5mm or 1.8mm, and specific point values between the above point values, are not exhaustive and for the sake of brevity.
Preferably, the polyvinyl alcohol has a number average molecular weight of 20000 to 100000, for example 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000 or 98000, and specific point values between the above point values, are not exhaustive, for reasons of brevity and conciseness.
Preferably, the mass ratio of the diatom shell to the polyvinyl alcohol is 1 (0.025-0.45), for example, may be 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.42, or 1:0.44, etc.
Preferably, the mass ratio of the diatom shell to the alumina is 1 (0.375-2), for example, may be 1:0.4, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, or 1:1.9, etc.
In the present invention, the porosity of the aerogel is not less than 90%, for example, 91%, 92%, 93%, 94%, 95%, 96%, 97% and the like.
In the invention, the material of the fiber aerogel further comprises an aqueous dispersing agent.
Preferably, the mass ratio of the diatom shell to the aqueous dispersant is 1 (0.0025-0.05), for example, 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.048, etc.
Preferably, the aqueous dispersing agent is selected from any one or a combination of at least two of polyacrylic acid, polyethylene glycol, sodium pyrophosphate or sodium silicate.
Preferably, the polyacrylic acid has a number average molecular weight of 5000 to 10000, and may be 5200, 5500, 6000, 6500, 7000, 7200, 7500, 8000, 8200, 8500, 9000, 9500, 9800 or 9000, for example, and specific point values among the above point values, are limited in length and for brevity, the present invention is not exhaustive of the specific point values included in the range.
Preferably, the polyethylene glycol has a number average molecular weight of 2000 to 8000, and may be 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 7800 or 7900, for example, and specific point values between the above point values, are limited in space and for brevity, the present invention is not exhaustive of the specific point values included in the range.
In a second aspect, the present invention provides a method for preparing the aerogel according to the first aspect, the method comprising the steps of: uniformly mixing the diatomite powder, the polyvinyl alcohol solution and the aqueous dispersing agent, adding aluminum oxide, heating and optionally performing ultrasonic dispersion to obtain an electrostatic spinning precursor solution; and carrying out electrostatic spinning on the electrostatic spinning precursor solution to obtain the aerogel.
In the invention, the diatom shell powder is prepared by grinding diatom shells.
Preferably, the milling method is ball milling.
Preferably, the rotation speed of the ball mill is 50-200 r/min, for example, 60r/min, 70r/min, 80r/min, 90r/min, 100r/min, 120r/min, 150r/min, 180r/min or 190r/min, and specific point values among the above point values are limited in space and for the sake of brevity, the present invention does not exhaustively list specific point values included in the range.
Preferably, the ball milling time is 1 to 4 hours, for example, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours or 3.9 hours, and specific point values among the above point values are limited in length and for brevity, the present invention is not exhaustive of the specific point values included in the range.
Preferably, the particle size of the diatom shell powder is 10-100 nm, for example, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 60nm, 70nm, 80nm, 90nm or 95nm, and specific point values between the above point values, are limited in length and for brevity, the present invention is not exhaustive of the specific point values included in the ranges.
Preferably, the alumina has a particle size of 10 to 100nm, for example, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 60nm, 70nm, 80nm, 90nm or 95nm, and specific point values between the above point values, are limited in length and for brevity, the invention is not intended to be exhaustive of the specific point values included in the range.
Preferably, the heating temperature is 30-50 ℃, such as 32 ℃, 35 ℃, 40 ℃, 42 ℃, 44 ℃, 46 ℃, 48 ℃ or 49 ℃, and specific point values between the above points, which are not exhaustive of the specific point values included in the range for reasons of space and for reasons of simplicity.
In the invention, the solvent of the polyvinyl alcohol solution is water.
Preferably, the polyvinyl alcohol solution contains 10-15% by mass of polyvinyl alcohol, for example 10.5%, 11%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 14.6%, 14.8% or 14.9%, and specific point values between the above point values, and the present invention is not intended to be exhaustive of the specific point values included in the range, for reasons of brevity and conciseness.
Preferably, the mass ratio of the diatom shell powder to the aqueous dispersant is 1 (0.0025-0.05), for example, 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.048, etc.
Preferably, the mass ratio of the diatom shell powder to the polyvinyl alcohol solution is 1 (0.3-3.6), for example, may be 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:2.8, 1:3, 1:3.2, 1:3.3 or 1:3.4, etc.
Preferably, the mass ratio of the diatom shell powder to the alumina is 1 (0.375-2), for example, may be 1:0.4, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, etc.
In the present invention, the voltage of the electrostatic spinning is 10-18 KV, for example, 10.5KV, 11KV, 12KV, 13KV, 14KV, 15KV, 16KV or 17KV, and specific point values between the above point values, which are limited in space and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.
Preferably, the number of the inner diameter of the needle head of the electrostatic spinning is 18-27G, for example, 22G.
Preferably, the ejection speed of the electrospinning is 0.5-1.5 mL/h, for example, may be 0.6mL/h, 0.7mL/h, 0.8mL/h, 0.9mL/h, 1.0mL/h, 1.1mL/h, 1.2mL/h, 1.3mL/h or 1.4mL/h, and specific point values between the above point values, which are limited in space and for simplicity, the present invention does not exhaustively list the specific point values included in the range.
Preferably, the rotational speed of the electrostatic spinning drum is 50-150 r/min, for example, 60r/min, 70r/min, 80r/min, 90r/min, 100r/min, 110r/min, 120r/min, 130r/min or 140r/min, and specific point values among the above point values are limited in space and for brevity, the present invention does not exhaustively list specific point values included in the range.
In the invention, the preparation method comprises the following steps:
(1) Ball milling the diatom shells for 1-4 hours at the rotating speed of 50-200 r/min to obtain diatom shell powder;
(2) Uniformly mixing the diatom shell powder obtained in the step (1), 10-15% polyvinyl alcohol aqueous solution and aqueous dispersing agent in a mass ratio of 1 (0.3-3.6) (0.0025-0.05), then adding aluminum oxide, heating to 30-50 ℃ and optionally performing ultrasonic dispersion to obtain an electrostatic spinning precursor solution; the mass ratio of the diatom shell powder to the alumina is 1 (0.375-2); the water-based dispersing agent is selected from any one or a combination of at least two of polyacrylic acid, polyethylene glycol, sodium pyrophosphate or sodium silicate;
(3) And (3) carrying out electrostatic spinning on the electrostatic spinning precursor solution obtained in the step (2) by adopting a needle with the inner diameter of 18-27G under the conditions of voltage of 10-18 KV, ejection speed of 0.5-1.5 mL/h and drum rotation speed of 50-150 r/min to obtain the aerogel.
In a third aspect, the present invention provides the use of an aerogel according to the first aspect in an infrared stealth material.
Compared with the prior art, the invention has the following beneficial effects:
according to the aerogel provided by the invention, the diatom shell with the porous structure is selected as the fiber aerogel material, and the three-dimensional porous structure is constructed among the fiber aerogels, so that the porosity of the aerogel is obviously improved under the combined action of the two, and the porosity is up to more than 90%. Through the screening of the content of each component, when the thickness of the aerogel is 0.05mm, the aerogel has obvious infrared stealth effect, the gray value can be as low as 33, and meanwhile, the flexibility of the silicon-based aerogel can be further improved, and the aerogel can resist 500 times of bending.
Drawings
FIG. 1 is a scanning electron microscope image of the surface morphology of the diatom shell powder obtained in example 1 of the present invention;
FIG. 2 is a scanning electron microscope image of the surface morphology of commercially available silica provided in comparative example 1 of the present invention.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
The materials used in the following examples and comparative examples of the present invention include:
polyvinyl alcohol: shanghai Ala dine 9002-89-5;
polyethylene glycol: shanghai microphone, 25322-68-3.
Example 1
The embodiment provides an aerogel and a preparation method thereof, wherein the aerogel is provided with a porous network structure formed by fiber aerogel; the material of the fiber aerogel comprises a combination of diatom shells, polyvinyl alcohol and aluminum oxide; the mass ratio of the diatom shell to the polyvinyl alcohol is 1:0.25; the mass ratio of the diatom shell to the alumina is 1:1.2.
The preparation method of the aerogel comprises the following steps:
(1) Ball milling the diatom shells for 2 hours at a rotating speed of 100r/min to obtain diatom shell powder;
(2) Uniformly mixing the diatom shell powder obtained in the step (1) and a polyvinyl alcohol aqueous solution with the concentration of 12% in a mass ratio of 1:2.1, then adding aluminum oxide, heating to 45 ℃, and performing ultrasonic dispersion for 30min to obtain an electrostatic spinning precursor solution; the mass ratio of the diatom shell powder to the alumina is 1:1.2; (3) And (3) carrying out electrostatic spinning on the electrostatic spinning precursor solution obtained in the step (2) by adopting a needle with the inner diameter of 22G under the conditions of voltage of 14KV, ejection speed of 1mL/h and drum rotation speed of 100r/min to obtain the aerogel.
Example 2
The embodiment provides an aerogel and a preparation method thereof, wherein the aerogel is provided with a porous network structure formed by fiber aerogel; the material of the fiber aerogel comprises a combination of diatom shells, polyvinyl alcohol and aluminum oxide; the mass ratio of the diatom shell to the polyvinyl alcohol is 1:0.025; the mass ratio of the diatom shell to the alumina is 1:0.375.
The preparation method of the aerogel comprises the following steps:
(1) Ball milling the diatom shells for 2 hours at a rotating speed of 100r/min to obtain diatom shell powder;
(2) Uniformly mixing the diatom shell powder obtained in the step (1) and 10% polyvinyl alcohol aqueous solution in a mass ratio of 1:0.25, then adding aluminum oxide, heating to 30 ℃, and performing ultrasonic dispersion for 30min to obtain an electrostatic spinning precursor solution; the mass ratio of the diatom shell powder to the alumina is 1:0.375; (3) And (3) carrying out electrostatic spinning on the electrostatic spinning precursor solution obtained in the step (2) by adopting a needle with the inner diameter of 18G under the conditions of 10KV voltage, 0.5mL/h pushing speed and 50r/min drum rotating speed, so as to obtain the aerogel.
Example 3
The embodiment provides an aerogel and a preparation method thereof, wherein the aerogel is provided with a porous network structure formed by fiber aerogel; the material of the fiber aerogel comprises a combination of diatom shells, polyvinyl alcohol and aluminum oxide; the mass ratio of the diatom shell to the polyvinyl alcohol is 1:0.45; the mass ratio of the diatom shell to the alumina is 1:2.
The preparation method of the aerogel comprises the following steps:
(1) Ball milling the diatom shells for 2 hours at a rotating speed of 100r/min to obtain diatom shell powder;
(2) Uniformly mixing the diatom shell powder obtained in the step (1) and a polyvinyl alcohol aqueous solution with the concentration of 15% in a mass ratio of 1:3, then adding aluminum oxide, heating to 50 ℃, and performing ultrasonic dispersion for 30min to obtain an electrostatic spinning precursor solution; the mass ratio of the diatom shell powder to the alumina is 1:2; (3) And (3) carrying out electrostatic spinning on the electrostatic spinning precursor solution obtained in the step (2) by adopting a needle with the inner diameter of 27G under the conditions of 18KV voltage, 1.5mL/h pushing speed and 150r/min drum rotating speed, so as to obtain the aerogel.
Example 4
The present example provides an aerogel and a method of making the same, which differs from example 1 only in that the mass ratio of the diatom shell to the polyvinyl alcohol is 1:0.01; in the preparation method, the mass ratio of the diatom shell powder to the polyvinyl alcohol aqueous solution is 1:0.08.
Example 5
The present example provides an aerogel and a method of making the same, which differs from example 1 only in that the mass ratio of the diatom shell to the polyvinyl alcohol is 1:0.6; in the preparation method, the mass ratio of the diatom shell powder to the polyvinyl alcohol aqueous solution is 1:5.
Example 6
The present example provides an aerogel and a method of making the same, which differs from example 1 only in that the diatom shell to alumina mass ratio is 1:0.2; in the preparation method, the mass ratio of the diatom shell powder to the polyvinyl alcohol aqueous solution is 1:0.2.
Example 7
The present example provides an aerogel and a method of making the same, which differs from example 1 only in that the diatom shell to alumina mass ratio is 1:2.5; in the preparation method, the mass ratio of the diatom shell powder to the polyvinyl alcohol aqueous solution is 1:2.5.
Example 8
The embodiment provides an aerogel and a preparation method thereof, wherein the aerogel is provided with a porous network structure formed by fiber aerogel; the material of the fiber aerogel comprises a combination of diatom shells, polyvinyl alcohol, aluminum oxide and polyethylene glycol; the mass ratio of the diatom shell to the polyvinyl alcohol is 1:0.25; the mass ratio of the diatom shell to the alumina is 1:1.2; the mass ratio of the diatom shell to the polyethylene glycol is 1:0.03.
The preparation method of the aerogel comprises the following steps:
(1) Ball milling the diatom shells for 2 hours at a rotating speed of 100r/min to obtain diatom shell powder;
(2) Uniformly mixing the diatom shell powder obtained in the step (1) and polyethylene glycol which is a polyvinyl alcohol aqueous solution with the concentration of 12% in a mass ratio of 1:2.1:0.03, then adding aluminum oxide, heating to 45 ℃, and performing ultrasonic dispersion for 30min to obtain an electrostatic spinning precursor solution; the mass ratio of the diatom shell powder to the alumina is 1:1.2; (3) And (3) carrying out electrostatic spinning on the electrostatic spinning precursor solution obtained in the step (2) by adopting a needle with the inner diameter of 20G under the conditions of voltage of 14KV, ejection speed of 1mL/h and drum rotation speed of 100r/min to obtain the aerogel.
Example 9
The embodiment provides an aerogel and a preparation method thereof, wherein the aerogel has a porous network structure; the material of the fiber aerogel comprises a combination of diatom shells, polyvinyl alcohol and polyethylene glycol; the mass ratio of the diatom shell to the polyvinyl alcohol is 1:0.25; the mass ratio of the diatom shell to the polyethylene glycol is 1:0.03.
The preparation method of the aerogel comprises the following steps:
(1) Ball milling the diatom shells for 2 hours at a rotating speed of 100r/min to obtain diatom shell powder;
(2) Uniformly mixing the diatom shell powder obtained in the step (1) and polyethylene glycol which is a polyvinyl alcohol aqueous solution with the concentration of 12% in a mass ratio of 1:2.1:0.03, and performing ultrasonic dispersion for 30min to obtain a precursor solution;
(3) And (3) freeze-drying the precursor solution obtained in the step (2) to obtain the aerogel.
Comparative example 1
This comparative example provides an aerogel and a method for preparing the same, which is different from example 1 in that the material of the fiber aerogel uses commercially available silicon dioxide instead of the diatom shell powder, and other components, contents and preparation method are the same as example 1; the particle size of the commercially available silica is 10 to 100nm.
Comparative example 2
This comparative example provides an aerogel and a method of making the same, which differs from example 1 in that the fibrous aerogel material does not include alumina, and the method of making does not include alumina, and the other components, amounts, and methods of making are the same as in example 1.
Comparative example 3
This comparative example provides an aerogel and a method of making the same, which differs from example 8 in that the diatom shell component is replaced with a commercially available silica component, and the method of making is the same as example 8.
Performance test:
scanning electron microscope test: scanning electron microscopy (VEGA 3LMH, tescan) was used to separately perform scanning electron microscopy tests on the diatom shell powder obtained in step (1) of example 1 and the commercially available silica provided in comparative example 1; the test results are shown in fig. 1 and 2;
porosity test: the aerogels provided in examples 1-9 and comparative examples 1-3 were tested for porosity according to the test method of GB/T33052-2016;
infrared stealth performance test: an infrared thermal imaging image of the aerogel output gray scale pattern provided in examples 1-9 and comparative examples 1-3 was obtained using a 320 x 240 resolution infrared imager to obtain an average gray scale value. The smaller the average gray value is, the darker the image color is, the smaller the infrared radiation amount on the surface of the object is, and the infrared stealth performance is better;
flexibility test: the aerogels provided in examples 1-9 and comparative examples 1-3 were clamped with a jig with rubber shims using a universal tester (model: instron 2367) and the jig spacing was adjusted. The stretching and compression of the film are achieved by the up-and-down displacement of the clamp. One stretching and compression process was considered to be 1 fold foldable and the test was repeated until the film was broken.
The test results are shown in table 1:
TABLE 1
From the data in table 1, it can be seen that polyvinyl alcohol as an electrospinning forming additive is beneficial to preparing the diatom shell based fiber aerogel by the electrospinning process. Too low a content is detrimental to molding, too low results in poor aerogel toughness (example 4), too high results in reduced porosity and reduced stealth performance (example 5). Polyethylene glycol is used as a diatom shell dispersing agent, so that the diatom shells are uniformly dispersed in the precursor solution, the uniformity and stability of the fiber aerogel can be improved, and the porosity and flexibility (examples 1-7 and 8) can be further improved. The alumina is used as the electrostatic spinning forming auxiliary agent, so that on one hand, viscosity adjustment is provided, on the other hand, an acidic environment is provided, the diatom shell base fiber aerogel is formed rapidly through an electrostatic spinning process, and the excessive content of the diatom shell base fiber aerogel can cause excessive viscosity of a precursor solution and easily block pinholes; too little viscosity has little effect on the precursor solution, decreasing the injection speed (spinning speed) (examples 1-5 and examples 6, 7, comparative example 2). The diatom ooze shell as porous natural silica, which is not only high in purity but also further increases the porosity of the aerogel due to its own multi-stage porosity, and at the same time, reduces the weight of the aerogel, exhibiting more excellent infrared stealth and flexibility (example 1 and comparative example 1). Compared with the aerogel prepared by the freeze-drying method, the aerogel prepared by the electrostatic spinning method provided by the invention has higher porosity, more excellent infrared stealth performance and better flexibility (example 1 and example 8).
The applicant states that the process of the invention is illustrated by the above examples, but the invention is not limited to, i.e. does not mean that the invention must be carried out in dependence on the above process steps. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of selected raw materials, addition of auxiliary components, selection of specific modes, etc. fall within the scope of the present invention and the scope of disclosure.
Claims (15)
1. An aerogel, wherein the aerogel has a porous network structure of fibrous aerogel; the material of the fiber aerogel comprises a combination of diatom shells, polyvinyl alcohol and aluminum oxide;
the thickness of the aerogel is 0.1-2 mm;
the number average molecular weight of the polyvinyl alcohol is 20000-100000;
the mass ratio of the diatom shell to the polyvinyl alcohol is 1 (0.025-0.45);
the mass ratio of the diatom shell to the alumina is 1 (0.375-2);
the porosity of the aerogel is more than or equal to 90 percent.
2. The aerogel of claim 1, wherein the fibrous aerogel material further comprises an aqueous dispersing agent.
3. The aerogel of claim 2, wherein the mass ratio of the diatom shell to the aqueous dispersant is 1 (0.0025 to 0.05).
4. The aerogel of claim 2, wherein the aqueous dispersing agent is selected from any one or a combination of at least two of polyacrylic acid, polyethylene glycol, sodium pyrophosphate, or sodium silicate.
5. The aerogel of claim 4, wherein the polyacrylic acid has a number average molecular weight of 5000 to 10000.
6. The aerogel of claim 4, wherein the polyethylene glycol has a number average molecular weight of 2000 to 8000.
7. A method of preparing an aerogel according to any one of claims 1 to 6, comprising the steps of: uniformly mixing the diatomite powder and the polyvinyl alcohol solution, adding aluminum oxide, heating and performing ultrasonic dispersion to obtain an electrostatic spinning precursor solution; carrying out electrostatic spinning on the electrostatic spinning precursor solution to obtain the aerogel;
the diatom shell powder is prepared by grinding diatom shells;
the grain size of the diatom shell powder is 10-100 nm;
the particle size of the alumina is 10-100 nm;
the solvent of the polyvinyl alcohol solution is water;
the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol solution is 10-15%;
the mass ratio of the diatom shell powder to the polyvinyl alcohol solution is 1 (0.3-3.6);
the mass ratio of the diatom shell powder to the alumina is 1 (0.375-2);
the voltage of the electrostatic spinning is 10KV to 18KV;
the ejection speed of the electrostatic spinning is 0.5-1.5 mL/h;
the rotating speed of the electrostatic spinning roller is 50-150 r/min.
8. The method of claim 7, wherein the milling is performed by ball milling.
9. The method according to claim 8, wherein the rotational speed of the ball mill is 50 to 200r/min.
10. The method of claim 8, wherein the ball milling is performed for a period of 1 to 4 hours.
11. The method of claim 7, wherein the heating is at a temperature of 30 to 50 ℃.
12. The method of making according to claim 7, wherein the mixing process further comprises an aqueous dispersant;
the mass ratio of the diatom shell powder to the aqueous dispersing agent is 1 (0.0025-0.05).
13. The method according to claim 7, wherein the number of the inside diameter of the electrospun needle is 18 to 27G.
14. The preparation method according to claim 7, characterized in that the preparation method comprises the steps of:
(1) Ball milling the diatom shells for 1-4 hours at the rotating speed of 50-200 r/min to obtain diatom shell powder;
(2) Uniformly mixing the diatom shell powder obtained in the step (1), 10-15% polyvinyl alcohol aqueous solution and aqueous dispersing agent in a mass ratio of 1 (0.3-3.6) (0.0025-0.05), then adding aluminum oxide, heating to 30-50 ℃ and optionally performing ultrasonic dispersion to obtain an electrostatic spinning precursor solution; the mass ratio of the diatom shell powder to the alumina is 1 (0.375-2); the water-based dispersing agent is selected from any one or a combination of at least two of polyacrylic acid, polyethylene glycol, sodium pyrophosphate or sodium silicate;
(3) And (3) carrying out electrostatic spinning on the electrostatic spinning precursor solution obtained in the step (2) by adopting a needle with the inner diameter of 18-27G under the conditions of voltage of 10-18 KV, ejection speed of 0.5-1.5 mL/h and drum rotation speed of 50-150 r/min to obtain the aerogel.
15. Use of an aerogel according to any of claims 1 to 6 in an infrared stealth material.
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| CN103599734A (en) * | 2013-11-22 | 2014-02-26 | 中国工程物理研究院核物理与化学研究所 | Aerogel material and preparation method thereof |
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| CN110170282A (en) * | 2019-05-07 | 2019-08-27 | 清华大学 | A kind of anisotropy stratiform inorfil aerogel material and preparation method thereof |
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| CN103599734A (en) * | 2013-11-22 | 2014-02-26 | 中国工程物理研究院核物理与化学研究所 | Aerogel material and preparation method thereof |
| CN108483452A (en) * | 2018-05-29 | 2018-09-04 | 南京工业大学 | A kind of preparation method of the blocky graded composite aeroge of low cost |
| CN109399645A (en) * | 2018-12-12 | 2019-03-01 | 陕西科诺材料科技有限公司 | A kind of SiO without solvent displacement2The atmospheric preparation method of aeroge |
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