CN116102836B - Layered electromagnetic shielding polymer composite foam and preparation method thereof - Google Patents
Layered electromagnetic shielding polymer composite foam and preparation method thereof Download PDFInfo
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- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
- H05K9/0083—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
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- H05K9/009—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive fibres, e.g. metal fibres, carbon fibres, metallised textile fibres, electro-conductive mesh, woven, non-woven mat, fleece, cross-linked
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- C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
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- C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
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Abstract
The application discloses a layered electromagnetic shielding polymer composite foam and a preparation method thereof, and relates to the technical field of composite material manufacturing; the preparation method of the composite foam comprises the following steps: the method comprises the steps of synthesizing a magnetic hydroxyl iron compound by an in-situ growth method, preparing a dispersion liquid component I and a dispersion liquid component II by utilizing the magnetic hydroxyl iron compound and a fiber component respectively, sequentially paving the two dispersion liquids on a glass plate, and preparing the polymer foam composite material by a steam-induced phase separation method. The foam composite material prepared by the application has the advantages of high shielding, low reflection, low density, corrosion resistance and the like, is simple in preparation process and low in cost, is suitable for large-scale industrial production, and is very easy to be widely applied to electronic equipment and dense systems in the fields of 5G communication technology and the like.
Description
Technical Field
The application relates to the technical field of composite material manufacturing, in particular to a layered structure electromagnetic shielding polymer composite foam and a preparation method thereof.
Background
Electromagnetic radiation can not only interfere with the operation of electronic equipment, but can also present serious health problems to humans. Therefore, the design and development of electromagnetic shielding materials with good shielding properties have attracted considerable attention in order to better reduce electromagnetic pollution. Electromagnetic radiation, a non-visible, non-touch, but ubiquitous pollution factor, has an intangible adverse effect on human health and the environment.
In recent years, electronic components and communication devices have been developed in the direction of more precision, multifunction, and weight reduction, and higher demands have been made on the application of electromagnetic shielding materials. Not only is the shielding effectiveness required to be high, but also the shielding effectiveness is required to have the characteristics of low density, high strength, oxidation resistance and the like. Compared with the traditional metal electromagnetic shielding material, the conductive polymer composite material has the advantages of light weight, corrosion resistance, easiness in processing, adjustable conductivity, wide absorption band and the like, and has been one of the mainstream shielding materials in recent years.
The shielding performance can be improved by regulating and controlling the microstructure and the macroscopic morphology of the shielding material. Particularly, the pore structure is introduced into the polymer matrix composite material, so that the density of the material can be reduced, the specific strength can be improved, and the reflection of the surface of the material on electromagnetic waves can be reduced. The micro structure (such as the diameter of a cell, the density of the cell, the thickness of a hole wall and the like) and the macro morphology (such as a honeycomb net structure, a sandwich structure, a composite laminated structure and the like) of the polymer-based foam material are regulated, so that the absorption loss of electromagnetic waves is enhanced, the shielding efficiency is improved, the secondary pollution of the electromagnetic waves is effectively reduced, the use frequency range is widened, and the polymer-based foam material can meet the requirements of different use environments on the shielding material.
The application provides a layered electromagnetic shielding polymer composite foam and a preparation method thereof, which greatly improve electromagnetic wave absorption efficiency, reduce the reflectivity of electromagnetic waves on the surface of a material, reduce secondary pollution and greatly reduce the density of a composite system.
Disclosure of Invention
The application aims to provide a layered electromagnetic shielding polymer composite foam and a preparation method thereof, which are used for solving the following technical problems:
how to improve the electromagnetic wave absorption efficiency of the polymer composite material, reduce the reflectivity of electromagnetic waves on the surface of the material and reduce the density of a composite system.
The aim of the application can be achieved by the following technical scheme:
the preparation method of the layered electromagnetic shielding polymer composite foam comprises the following steps:
(1) FeCl is added 3 ·6H 2 Adding O solution into the reaction vessel, and continuously adding NaBH 4 The solution is reacted and kept stand, sediment in a reaction container is sucked by a magnet and transferred into a beaker containing deionized water, the mechanical stirring is carried out for 5 to 60 minutes at room temperature, the sediment in the beaker is collected by the magnet, the sediment is washed and dried by ethanol solution to obtain black powder, the black powder is placed in a tubular furnace and calcined in an inert gas atmosphere containing hydrogen to obtain a flaky magnetic hydroxyl iron compound;
(2) Dispersing a magnetic hydroxyl iron compound in the first solvent component, adding the first fluoroplastic component, and uniformly stirring to obtain a first dispersion liquid component; dispersing the fiber component in a second solvent component, adding a second fluoroplastic component, and uniformly stirring to obtain a second dispersion liquid component;
(3) Pouring the second dispersion liquid component into a glass plate for tiling, pouring the first dispersion liquid component into the glass plate for tiling to form an upper-lower layer structure, standing for 12h in a constant temperature and humidity box, taking out, soaking with deionized water, washing and vacuum drying to obtain the foam composite material.
As a further scheme of the application: the heating rate of the tube furnace in the step (1) is 2-5 ℃/min, the temperature is raised to 400-800 ℃ and the calcination is carried out for 5 hours, and the inert gas containing hydrogen is continuously introduced in the cooling process after the calcination.
As a further scheme of the application: the content of hydrogen in the inert gas containing hydrogen in the step (1) accounts for 2 vt-5 vt of the total gas, and the inert gas is any one of nitrogen, argon and helium.
As a further scheme of the application: in the step (2), the fiber component is one or more of single-wall carbon nano tubes, multi-wall carbon nano tubes, carbon fibers and carbon nano wires which are mixed according to any ratio.
As a further scheme of the application: the addition amount of the magnetic hydroxyl iron compound in the step (2) is 10-40 wt% of the total amount of the magnetic hydroxyl iron compound and the fluoroplastic component; the addition amount of the first fluoroplastic component is 5-30wt% of the total amount of the first fluoroplastic component and the first solvent component.
As a further scheme of the application: the addition amount of the fiber component in the step (2) is 5-25 wt% of the total amount of the fiber component and the fluoroplastic component; the addition amount of the second fluoroplastic component is 5-30wt% of the total amount of the second fluoroplastic component and the second solvent component.
As a further scheme of the application: the experimental conditions in the constant temperature and humidity box in the step (3) are that the temperature is 20-30 ℃ and the humidity is 85-95%.
As a further scheme of the application: the first solvent component is any one of N, N-dimethylformamide and N-methylpyrrolidone; the second solvent component is any one of N, N-dimethylformamide and N-methylpyrrolidone; the first solvent component and the second solvent component may be the same or different.
As a further scheme of the application: the fluoroplastic is any one of perfluoro copolymer, poly-perfluoro alkoxy resin, poly-trifluoro vinyl chloride, ethylene-trifluoro vinyl chloride copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride and polyvinyl fluoride.
As a further scheme of the application: the thickness of the upper and lower layers is 2mm-50mm.
The laminated electromagnetic shielding polymer composite foam is prepared by any one of the preparation methods.
The application has the beneficial effects that:
(1) The magnetic hydroxyl iron compound prepared by the in-situ growth method is formed by three-dimensional flower-shaped particles assembled by two-dimensional lamellar substances, and the multidimensional absorber with the geometric effect can increase magnetic response or magnetic flux and the like to improve the attenuation effect on electromagnetic waves. The composite foam prepared by the water vapor induced phase separation method is characterized by an electron scanning microscope, so that part of carbon fibers and magnetic hydroxyl iron compounds which are exposed in the microspheres can be clearly seen; in the formed multilayer polymer composite foam, the magnetic hydroxyl iron particles can well generate magnetic loss on electromagnetic waves, enhance microwave absorption, reduce reflection and reduce secondary pollution of the electromagnetic waves; the carbon fiber can exert an electric loss effect on electromagnetic waves, so that the attenuation of the system on the electromagnetic waves is further enhanced; meanwhile, more heterogeneous interfaces and interface polarization are generated among the conductive fiber components, the magnetic hydroxyl iron compound and the high polymer matrix, so that the interface loss of electromagnetic waves is increased.
(2) The foam material is added with the fiber component and the magnetic hydroxyl iron compound as conductive particles and the magnetic wave absorber, and a foam structure which is layered up and down is designed, and the open-cell structure improves the impedance matching characteristic of the surface of the material, so that electromagnetic waves are not easy to reflect on the surface and are easier to be incident into the material. The incident electromagnetic wave is subjected to multiple reflection and refraction between the hole walls, and absorption loss is enhanced. The upper and lower layered structure design can select different conductive wave absorbers according to performance requirements, so as to meet the requirements of different occasions. In the application, a first dispersion liquid component prepared by a magnetic hydroxyl iron compound is positioned on the upper layer of a sample, and carbon fibers are mainly positioned on the lower layer. When electromagnetic waves enter from the upper layer and are absorbed by the wave absorbing agent of the layer, the carbon fiber layer with higher electric conductivity is reflected to the absorption layer for further absorption, so that a special absorption-reflection-reabsorption process is formed, and the whole system has higher shielding performance and lower electromagnetic wave reflection. The vector network analyzer is adopted to test and characterize the composite sample, and the result shows that the electromagnetic shielding performance of the composite sample is greatly improved and mainly comes from absorption contribution.
(3) The preparation method provided by the application is simple, scientific, efficient and low in cost, is suitable for large-scale industrial production, and is very easy to be widely applied to electronic equipment and dense systems in the fields of 5G communication technology and the like.
Drawings
The application is further described below with reference to the accompanying drawings.
FIG. 1 is an SEM image of the lower layer of the layered electromagnetic shielding foam prepared in example 1 of the present application, as characterized by a Scanning Electron Microscope (SEM);
FIG. 2 is a Scanning Electron Microscope (SEM) image of a magnetic iron oxyhydroxide material of example 5 of the present application;
FIG. 3 is a graph showing comparison of the foam density measurement data obtained in comparative example 4, comparative example 1 and comparative example 2 according to the present application;
FIG. 4 is a graph showing analysis results of performance tests of foams prepared in example 4, comparative example 1 and comparative example 2 according to the present application using a vector network analyzer.
Description of the embodiments
The following description of the embodiments of the present application will be made clearly and completely, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Examples
The preparation method of the layered electromagnetic shielding polymer composite foam comprises the following steps:
(1) 1.80g FeCl 3 ·6H 2 O is dissolved in 600mL deionized water to obtain FeCl 3 ·6H 2 An O solution; 0.36g NaBH 4 Adding the mixture into 240mL of deionized water for dissolving to obtain NaBH completely 4 A solution; then stirring the NaBH prepared above 4 Dropwise adding the solution to FeCl 3 ·6H 2 O solution; sucking the black precipitate with a magnet, transferring to a beaker I containing deionized water, mechanically stirring at room temperature for 10min, collecting the black precipitate in the beaker I after stirring, washing with absolute ethyl alcohol, drying to obtain black powder, calcining in a tube furnace with nitrogen atmosphere containing 2vt% hydrogen, and heating at high speedThe rate is increased to 550 ℃ per minute and calcined for 5 hours, so as to obtain the magnetic hydroxyl iron compound;
(2) Weighing 20 parts by weight of a magnetic hydroxyl iron compound, dispersing the magnetic hydroxyl iron compound in 720 parts by weight of N, N-dimethylformamide, adding 80 parts by weight of polyvinylidene fluoride, and heating and stirring in a water bath at 70 ℃ to form a uniform dispersion component I; weighing 20 parts by weight of single-walled carbon nanotubes, dispersing the single-walled carbon nanotubes in 600 parts by weight of N, N-dimethylformamide, adding 80 parts by weight of polyvinylidene fluoride, heating in a water bath at 70 ℃ and uniformly stirring to obtain a dispersion liquid component II;
(4) Pouring the second dispersion liquid component prepared in the step (2) into a glass flat plate for tiling, pouring the first dispersion liquid component prepared in the step (2) into a flat plate for tiling to form an upper layer structure and a lower layer structure, controlling the total thickness of the foam structure composite material to be 15mm, placing the foam structure composite material into a constant temperature and humidity box with the humidity of 90% and the temperature of 25 ℃ for 12 hours, taking out, soaking the foam structure composite material in deionized water, washing the foam structure composite material, freezing the foam structure composite material in a vacuum freeze drying box for 12 hours, and then drying the foam structure composite material in vacuum for 48 hours.
Referring to fig. 1, the lower layer of the foam composite material prepared in step (4) of example 1 was characterized by using a Scanning Electron Microscope (SEM), and the SEM image shows that the carbon nanotubes are coated on the PVDF substrate, so as to form a good conductive path.
Examples
The preparation method of the layered electromagnetic shielding polymer composite foam comprises the following steps:
(1) 1.80g FeCl 3 ·6H 2 O is dissolved in 600mL deionized water to obtain FeCl 3 ·6H 2 An O solution; 0.36g NaBH 4 Adding the mixture into 240mL of deionized water for dissolving to obtain NaBH completely 4 A solution; then stirring the NaBH prepared above 4 Dropwise adding the solution to FeCl 3 ·6H 2 O solution; sucking the black precipitate with a magnet, transferring to a beaker I containing deionized water, mechanically stirring at room temperature for 20min, collecting the black precipitate in the beaker I with the magnet after stirring, washing with absolute ethyl alcohol, drying to obtain black powder, calcining the black powder in a tube furnace which contains nitrogen with 2vt% hydrogenCalcining for 5 hours in an air atmosphere at a heating rate of 2 ℃/min to 600 ℃/min to obtain a magnetic hydroxyl iron compound;
(2) Weighing 25 parts by weight of a magnetic hydroxyl iron compound, dispersing the magnetic hydroxyl iron compound in 750 parts by weight of N, N-dimethylformamide, adding 75 parts by weight of polyvinylidene fluoride, and heating and stirring in a water bath at 80 ℃ to form a uniform dispersion component I; weighing 25 parts by weight of carbon fibers, dispersing the carbon fibers in 660 parts by weight of N, N-dimethylformamide, adding 75 parts by weight of polyvinylidene fluoride, and heating and stirring the mixture uniformly in a water bath at 80 ℃ to obtain a dispersion liquid component II;
(3) Pouring the first dispersion liquid component prepared in the step (2) into a glass flat plate for tiling, pouring the second dispersion liquid component prepared in the step (2) into a flat plate for tiling to form an upper layer structure and a lower layer structure, controlling the total thickness of the foam structure composite material to be 10mm, placing the foam structure composite material into a constant temperature and humidity box with the humidity of 95% and the temperature of 28 ℃ for 12 hours, taking out, soaking the foam structure composite material in deionized water, washing the foam structure composite material, freezing the foam structure composite material in a vacuum freeze drying box for 12 hours, and then drying the foam structure composite material in vacuum for 48 hours.
Examples
The preparation method of the layered electromagnetic shielding polymer composite foam comprises the following steps:
(1) 1.80g FeCl 3 ·6H 2 O is dissolved in 600mL deionized water to obtain FeCl 3 ·6H 2 An O solution; 0.36g NaBH 4 Adding the mixture into 240mL of deionized water for dissolving to obtain NaBH completely 4 A solution; then stirring the NaBH prepared above 4 Dropwise adding the solution to FeCl 3 ·6H 2 O solution; sucking the black precipitate by a magnet and transferring the black precipitate into a beaker I containing deionized water, mechanically stirring the mixture at room temperature for 30min, after stirring, sucking and collecting the black precipitate in the beaker I into a beaker II by using the magnet, washing the black precipitate by absolute ethyl alcohol, drying the black precipitate to obtain black powder, calcining the black powder in a tube furnace which is in a nitrogen atmosphere containing 2vt percent of hydrogen, and calcining the black powder for 5h at a heating rate of 2 ℃/min to 700 ℃/min to obtain a magnetic hydroxyl iron compound;
(2) 30 parts by weight of a magnetic hydroxyl iron compound is weighed and dispersed in 720 parts by weight of N, N-dimethylformamide, 75 parts by weight of polyvinylidene fluoride is added, and the mixture is heated and stirred in a water bath at 75 ℃ to form a uniform dispersion component I; weighing 20 parts by weight of multi-wall carbon nanotubes, dispersing in 700 parts by weight of N, N-dimethylformamide, adding 80 parts by weight of polyvinylidene fluoride, heating in a 75 ℃ water bath, and uniformly stirring to obtain a dispersion liquid component II;
(3) Pouring the first dispersion liquid component prepared in the step (2) into a glass flat plate for tiling, pouring the second dispersion liquid component prepared in the step (2) into a flat plate for tiling to form an upper layer structure and a lower layer structure, controlling the total thickness of the foam structure composite material to be 5mm, placing the foam structure composite material into a constant temperature and humidity box with the humidity of 95% and the temperature of 25 ℃ for 12 hours, taking out, soaking the foam structure composite material in deionized water, washing the foam structure composite material, freezing the foam structure composite material in a vacuum freeze drying box for 12 hours, and then drying the foam structure composite material in vacuum for 48 hours.
Examples
The preparation method of the layered electromagnetic shielding polymer composite foam comprises the following steps:
(1) 1.80g FeCl 3 ·6H 2 O is dissolved in 600mL deionized water to obtain FeCl 3 ·6H 2 An O solution; 0.36g NaBH 4 Adding the mixture into 240mL of deionized water for dissolving to obtain NaBH completely 4 A solution; then stirring the NaBH prepared above 4 Dropwise adding the solution to FeCl 3 ·6H 2 O solution; sucking the black precipitate by a magnet and transferring the black precipitate into a beaker I containing deionized water, mechanically stirring the mixture at room temperature for 40min, after stirring, sucking and collecting the black precipitate in the beaker I into a beaker II by using the magnet, washing the black precipitate by absolute ethyl alcohol, drying the black precipitate to obtain black powder, calcining the black powder in a tube furnace which is in a nitrogen atmosphere containing 2vt percent of hydrogen, and calcining the black powder for 5h at a heating rate of 3 ℃/min to 650 ℃/min to obtain a magnetic hydroxyl iron compound;
(2) 30 parts by weight of a magnetic hydroxyl iron compound is weighed and dispersed in 800 parts by weight of N, N-dimethylformamide, 70 parts by weight of polyvinylidene fluoride is added, and the mixture is heated and stirred in a water bath at 70 ℃ to form a uniform dispersion component I; 15 parts by weight of carbon fiber is weighed and dispersed in 680 parts by weight of N, N-dimethylformamide, 85 parts by weight of polyvinylidene fluoride is added, and the mixture is heated and stirred uniformly in a water bath at 80 ℃ to obtain a dispersion liquid component II;
(3) Pouring the first dispersion liquid component prepared in the step (2) into a glass flat plate for tiling, pouring the second dispersion liquid component prepared in the step (2) into a flat plate for tiling to form an upper layer structure and a lower layer structure, controlling the total thickness of the foam structure composite material to be 2mm, placing the foam structure composite material into a constant temperature and humidity box with the humidity of 90% and the temperature of 28 ℃ for 12 hours, taking out, soaking the foam structure composite material in deionized water, washing the foam structure composite material, freezing the foam structure composite material in a vacuum freeze drying box for 12 hours, and then drying the foam structure composite material in vacuum for 48 hours.
Examples
The preparation method of the layered electromagnetic shielding polymer composite foam comprises the following steps:
(1) 1.80g FeCl 3 ·6H 2 O is dissolved in 600mL deionized water to obtain FeCl 3 ·6H 2 An O solution; 0.36g NaBH 4 Adding the mixture into 240mL of deionized water for dissolving to obtain NaBH completely 4 A solution; then stirring the NaBH prepared above 4 Dropwise adding the solution to FeCl 3 ·6H 2 O solution; sucking the black precipitate by a magnet and transferring the black precipitate into a beaker I containing deionized water, mechanically stirring the mixture at room temperature for 40min, after stirring, sucking and collecting the black precipitate in the beaker I into a beaker II by using the magnet, washing the black precipitate by absolute ethyl alcohol, drying the black precipitate to obtain black powder, calcining the black powder in a tubular furnace which is in a nitrogen atmosphere containing 2vt percent of hydrogen, and calcining the black powder for 5h at a heating rate of 3 ℃/min to 750 ℃/min to obtain a magnetic hydroxyl iron compound;
(2) Weighing 25 parts by weight of a magnetic hydroxyl iron compound, dispersing in 760 parts by weight of N, N-dimethylformamide, adding 75 parts by weight of polyvinylidene fluoride, and heating and stirring in a water bath at 80 ℃ to form a uniform dispersion component I; 15 parts by weight of multi-wall carbon nano tubes are weighed and dispersed in 650 parts by weight of N, N-dimethylformamide, 85 parts by weight of polyvinylidene fluoride is added, and the mixture is heated and stirred uniformly in a water bath at 80 ℃ to obtain a dispersion liquid component II;
(3) Pouring the first dispersion liquid component prepared in the step (2) into a glass flat plate for tiling, pouring the second dispersion liquid component prepared in the step (2) into a flat plate for tiling to form an upper layer structure and a lower layer structure, controlling the total thickness of the foam structure composite material to be 20mm, placing the foam structure composite material into a constant temperature and humidity box with the humidity of 95% and the temperature of 25 ℃ for 12 hours, taking out, soaking the foam structure composite material in deionized water, washing the foam structure composite material, freezing the foam structure composite material in a vacuum freeze drying box for 12 hours, and then drying the foam structure composite material in vacuum for 48 hours.
Referring to fig. 2, the magnetic hydroxy iron compound prepared in the step (1) of example 5 was characterized by using a Scanning Electron Microscope (SEM), and the SEM image shows that the magnetic hydroxy iron compound has a three-dimensional flower-like heterostructure composed of two-dimensional plates and has a uniform size.
Comparative example 1
A method of preparing a foam material comprising the steps of:
adding 70 parts by weight of polyvinylidene fluoride into 800 parts by weight of N, N-dimethylformamide, heating and stirring in a water bath at 70 ℃ to form uniform dispersion liquid, pouring the dispersion liquid into a glass flat plate for tiling, controlling the total thickness to be 2mm, placing the glass flat plate into a constant temperature and humidity box with the humidity of 90% and the temperature of 28 ℃ for 12 hours, taking out, soaking in deionized water, washing, freezing in a vacuum freeze drying box for 12 hours, and then drying in vacuum for 48 hours to obtain the foam material.
Comparative example 2
A method of preparing a foam material comprising the steps of:
(1) 1.80g FeCl 3 ·6H 2 O is dissolved in 600mL deionized water to obtain FeCl 3 ·6H 2 An O solution; 0.36g NaBH 4 Adding the mixture into 240mL of deionized water for dissolving to obtain NaBH completely 4 A solution; then stirring the NaBH prepared above 4 Dropwise adding the solution to FeCl 3 ·6H 2 O solution; sucking the black precipitate by a magnet and transferring the black precipitate into a beaker I containing deionized water, mechanically stirring the mixture at room temperature for 40min, after stirring, sucking and collecting the black precipitate in the beaker I into a beaker II by using the magnet, washing the black precipitate by absolute ethyl alcohol, drying the black precipitate to obtain black powder, calcining the black powder in a tube furnace which is in a nitrogen atmosphere containing 2vt percent of hydrogen, and calcining the black powder for 5h at a heating rate of 3 ℃/min to 650 ℃/min to obtain a magnetic hydroxyl iron compound;
(2) 30 parts by weight of a magnetic hydroxyl iron compound is weighed and dispersed in 800 parts by weight of N, N-dimethylformamide, 70 parts by weight of polyvinylidene fluoride is added, and the mixture is heated and stirred in a water bath at 70 ℃ to form a uniform dispersion component I;
(3) And (3) pouring the first dispersion liquid component prepared in the step (2) into a glass flat plate for tiling, controlling the total thickness to be 2mm, placing the glass flat plate into a constant temperature and humidity box with the humidity of 90% and the temperature of 28 ℃ for 12 hours, taking out the glass flat plate, soaking the glass flat plate in deionized water, washing the glass flat plate, freezing the glass flat plate in a vacuum freeze drying box for 12 hours, and then drying the glass flat plate in vacuum for 48 hours to obtain the foam material.
Referring to fig. 3, the densities of the foams prepared in example 4 and comparative examples 1-2 and the fluororesin were measured, and the results showed that the densities of the foam samples were reduced by nearly half as compared to the pure resin, and that the densities of the different foam samples were not greatly different.
Referring to fig. 4, the foams prepared in example 4 and comparative examples 1-2 were tested for performance using a vector network analyzer, and it can be seen from fig. 4 (a) that the composite foam prepared in example 4 of the present application has much higher shielding efficiency than the foam prepared in comparative example 1 and the foam prepared in comparative example 2 and only added with the magnetic iron oxyhydroxide material. In fig. 4 (b), SER, SET, SEA represents the reflection efficiency, the total shielding efficiency and the absorption efficiency, respectively, and the results show that the material prepared in example 4 of the present application has excellent electromagnetic shielding efficiency, and the shielding mechanism is mainly absorption.
The foregoing describes one embodiment of the present application in detail, but the description is only a preferred embodiment of the present application and should not be construed as limiting the scope of the application. All equivalent changes and modifications within the scope of the present application are intended to be covered by the present application.
Claims (5)
1. The preparation method of the layered structure electromagnetic shielding polymer composite foam is characterized by comprising the following steps of:
(1) FeCl is added 3 ·6H 2 Adding O solution into the reaction vessel, and continuously adding NaBH 4 Standing the reaction, and precipitating in the reaction vessel by using a magnetSucking and transferring the material into a beaker containing deionized water, mechanically stirring for 5-60min at room temperature, collecting precipitate in the beaker by using a magnet, washing the precipitate with ethanol solution, drying to obtain black powder, placing the black powder into a tube furnace, and calcining in an inert gas atmosphere containing hydrogen to obtain a flaky magnetic hydroxyl iron compound;
(2) Dispersing a magnetic hydroxyl iron compound in the first solvent component, adding the first fluoroplastic component, and uniformly stirring to obtain a first dispersion liquid component; dispersing the fiber component in a second solvent component, adding a second fluoroplastic component, and uniformly stirring to obtain a second dispersion liquid component; wherein the fiber component is one or more of single-wall carbon nanotubes, multi-wall carbon nanotubes, carbon fibers and carbon nanowires, which are mixed according to any ratio; the addition amount of the magnetic hydroxyl iron compound is 10-40 wt% of the total amount of the magnetic hydroxyl iron compound and the fluoroplastic component; the addition amount of the fiber component is 5-25 wt% of the total amount of the fiber component and the fluoroplastic component; the first solvent component is any one of N, N-dimethylformamide and N-methylpyrrolidone; the second solvent component is any one of N, N-dimethylformamide and N-methylpyrrolidone; the first solvent component and the second solvent component may be the same or different;
(3) Pouring the second dispersion liquid component into a glass flat plate for tiling, pouring the first dispersion liquid component into the glass flat plate for tiling, placing the glass flat plate in a constant temperature and humidity box for 12 hours, taking out the glass flat plate, soaking the glass flat plate in deionized water, washing the glass flat plate, freezing the glass flat plate in a vacuum freeze drying box for 12 hours, and then drying the glass flat plate in vacuum for 48 hours to obtain the foam composite material.
2. The method for preparing the layered structure electromagnetic shielding polymer composite foam according to claim 1, wherein the heating rate of the tube furnace in the step (1) is 2-5 ℃/min, the temperature is raised to 400-800 ℃ and the calcination is carried out for 5 hours, and the inert gas containing hydrogen is continuously introduced in the cooling process after the calcination.
3. The method for preparing the layered structure electromagnetic shielding polymer composite foam according to claim 1, wherein the content of hydrogen in the inert gas containing hydrogen in the step (1) is 2vt% -5vt% of the total gas, and the inert gas is any one of nitrogen, argon and helium.
4. The method for preparing the layered electromagnetic shielding polymer composite foam according to claim 1, wherein the experimental conditions in the constant temperature and humidity box in the step (3) are that the temperature is 20-30 ℃ and the humidity is 85-95%.
5. A layered electromagnetic shielding polymer composite foam prepared by the preparation method of any one of claims 1-4.
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| CN103373833A (en) * | 2013-07-05 | 2013-10-30 | 燕山大学 | Preparation method of aluminum oxide-polyvinylidene fluoride-aluminum silicate ceramic fiber flame-retardant heat preservation composite material |
| CN109808267A (en) * | 2019-01-31 | 2019-05-28 | 常德力元新材料有限责任公司 | A kind of electromagnetic shielding composite material and preparation method thereof |
| CN115521635A (en) * | 2022-10-09 | 2022-12-27 | 合肥师范学院 | Heat-conducting shielding composite material with double-isolation network structure and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103373833A (en) * | 2013-07-05 | 2013-10-30 | 燕山大学 | Preparation method of aluminum oxide-polyvinylidene fluoride-aluminum silicate ceramic fiber flame-retardant heat preservation composite material |
| CN109808267A (en) * | 2019-01-31 | 2019-05-28 | 常德力元新材料有限责任公司 | A kind of electromagnetic shielding composite material and preparation method thereof |
| CN115521635A (en) * | 2022-10-09 | 2022-12-27 | 合肥师范学院 | Heat-conducting shielding composite material with double-isolation network structure and preparation method thereof |
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