CN108770327B - Gradient layered foamed wave-absorbing material and preparation method thereof - Google Patents
Gradient layered foamed wave-absorbing material and preparation method thereof Download PDFInfo
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- CN108770327B CN108770327B CN201810658619.XA CN201810658619A CN108770327B CN 108770327 B CN108770327 B CN 108770327B CN 201810658619 A CN201810658619 A CN 201810658619A CN 108770327 B CN108770327 B CN 108770327B
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Abstract
A gradient layered foamed wave-absorbing material, comprising: the foamed wave-absorbing layer is prepared by foaming a wave-absorbing agent and a soluble polymer matrix, and the mass fractions of the wave-absorbing agent in the foamed wave-absorbing layer are distributed in a gradient manner layer by layer. Because the mass fractions of the wave absorbing agents in the multiple layers of foaming wave absorbing layers are distributed in a gradient manner layer by layer, and the refractive index of the electromagnetic waves is gradually changed layer by layer when the electromagnetic waves enter the gradient layered foaming wave absorbing material from the air, the impedance matching characteristic of the gradient layered foaming wave absorbing material and the air is improved, the reflection of the electromagnetic waves on the surface of the gradient layered foaming wave absorbing material is favorably reduced, and the absorption of the electromagnetic waves in the material is increased.
Description
Technical Field
The invention relates to the technical field of wave-absorbing materials, and particularly relates to a gradient layered foaming wave-absorbing material and a preparation method thereof.
Background
With the development of modern science and technology, the influence of electromagnetic wave radiation on the environment is increasing day by day. Electromagnetic radiation causes direct and indirect damage to the human body through thermal, non-thermal, cumulative effects.
Wave-absorbing materials refer to materials that absorb or substantially attenuate the energy of electromagnetic waves incident on their surfaces, thereby reducing electromagnetic interference.
Disclosure of Invention
The invention aims to provide a gradient layered foam wave-absorbing material which has better wave-absorbing performance.
The invention also aims to provide a preparation method of the gradient layered foam wave-absorbing material, and the foam wave-absorbing material with good quality can be prepared by the method.
The technical problem to be solved by the invention is realized by adopting the following technical scheme.
The invention provides a gradient layered foaming wave-absorbing material, which comprises: the foamed wave-absorbing layer is prepared by foaming a wave-absorbing agent and a soluble polymer matrix, and the mass fractions of the wave-absorbing agent in the foamed wave-absorbing layer are distributed in a gradient manner layer by layer.
A preparation method of the gradient layered foaming wave-absorbing material comprises the following steps:
dissolving a wave absorbing agent and a soluble polymer matrix in a first organic solvent according to different preset mass ratios, performing ultrasonic treatment to obtain a first mixed solution, adding the first mixed solution into water to precipitate a blend of the wave absorbing agent and the soluble polymer matrix, and filtering to obtain a blend precipitate of the wave absorbing agent and the soluble polymer matrix; drying the blend precipitate to obtain a composite material with the wave absorbing agent mass fraction in gradient distribution;
and dissolving the composite material in a second solvent to obtain a second mixed solution, sequentially cooling the second mixed solution containing the wave absorbing agents with different mass fractions at the temperature of-30 ℃ according to a preset sequence so that the second solvent is crystallized into a solid state, the composite material is separated out, and finally obtaining the multilayer foaming wave absorbing layer with the wave absorbing agent mass fractions distributed in a layer-by-layer gradient manner.
A preparation method of the gradient layered foaming wave-absorbing material comprises the following steps:
dissolving a wave absorbing agent and a soluble polymer matrix in a first organic solvent according to different preset mass ratios, performing ultrasonic treatment to obtain a first mixed solution, adding the first mixed solution into water to precipitate a blend of the wave absorbing agent and the soluble polymer matrix, and filtering to obtain a blend precipitate of the wave absorbing agent and the soluble polymer matrix; drying the blend precipitate to obtain a composite material with the wave absorbing agent mass fraction in gradient distribution;
the composite material is paved layer by layer in a mode that the mass fractions of the wave absorbing agents are distributed in a gradient manner, and the paved multilayer composite material is subjected to hot press molding and foaming under the conditions of 160-180 ℃ and 3-6 MPa.
The embodiment of the invention has the beneficial effects that:
the gradient layered foaming wave-absorbing material disclosed by the invention is of a gradient multilayer structure, and the foaming wave-absorbing layers are provided with foam holes, so that the foam holes are beneficial to playing a strong electromagnetic wave loss role in the foaming wave-absorbing layers. In addition, the mass fractions of wave absorbers in the multiple layers of foaming wave-absorbing layers are distributed in a gradient manner layer by layer, and the refractive index of electromagnetic waves passing through the gradient layered foaming wave-absorbing material when the electromagnetic waves enter the gradient layered foaming wave-absorbing material from the air is gradually changed layer by layer, so that the impedance matching characteristic of the gradient layered foaming wave-absorbing material and the air is improved. According to the impedance matching principle, the change of the content gradient of the filler in the material is beneficial to reducing the reflection of electromagnetic waves on the surface of the material and increasing the absorption of the electromagnetic waves in the material, so that the loss of the electromagnetic waves is enhanced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a graph of the test results of the wave absorption performance of the gradient layered foamed wave-absorbing material of embodiment 1 and the layered foamed wave-absorbing material of comparative example 1;
FIG. 2 is a graph of the test results of the wave absorption performance of the gradient layered foamed wave-absorbing material of embodiment 2 and the layered foamed wave-absorbing material of comparative example 2;
FIG. 3 is a graph showing the test results of the wave absorption performance of the gradient layered foamed wave-absorbing material of embodiment 3 and the layered foamed wave-absorbing material of comparative example 3;
FIG. 4 is a graph of the test results of the wave absorption performance of the gradient layered foamed wave-absorbing material of embodiment 4 of the present invention and the layered foamed wave-absorbing material of comparative example 4;
FIG. 5 is a graph showing the test results of the wave absorption performance of the gradient layered foamed wave-absorbing material of embodiment 5 and the layered foamed wave-absorbing material of comparative example 5;
FIG. 6 is a graph showing the test results of the wave absorption performance of the gradient layered foamed wave-absorbing material of embodiment 6 and the layered foamed wave-absorbing material of comparative example 6;
FIG. 7 is a graph showing the test results of the wave absorption performance of the gradient layered foamed wave-absorbing material of example 7 and the layered foamed wave-absorbing material of comparative example 7;
FIG. 8 is a graph of the test results of the wave absorption performance of the gradient layered foamed wave-absorbing material of example 8 of the present invention and the layered foamed wave-absorbing material of comparative example 8.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The following is a detailed description of the preparation method of the gradient layered foam wave-absorbing material according to the embodiment of the present invention.
A gradient layered foamed wave-absorbing material, comprising: the foamed wave-absorbing layer is prepared by foaming a wave-absorbing agent and a soluble polymer matrix, and the mass fractions of the wave-absorbing agent in the foamed wave-absorbing layer are distributed in a gradient manner layer by layer.
The gradient layered foaming wave-absorbing material is of a gradient multilayer structure, and a large number of layer interfaces are arranged in the wave-absorbing material of the gradient multilayer structure, so that the multiple reflection of electromagnetic waves can be caused, the transmission process of the electromagnetic waves is increased, and the loss of the electromagnetic waves is enhanced.
In addition, the foam wave-absorbing layer is provided with foam holes, and the foam holes are beneficial to playing a role of stronger electromagnetic wave loss. And the mass fractions of the wave absorbing agents in the multiple layers of foaming wave absorbing layers are distributed in a gradient manner layer by layer, and the refractive index of the electromagnetic waves passing through the gradient layered foaming wave absorbing material from the air to the inside of the gradient layered foaming wave absorbing material is gradually changed layer by layer, so that the impedance matching characteristic of the gradient layered foaming wave absorbing material and the air is improved, the reflection of the electromagnetic waves on the surface of the gradient layered foaming wave absorbing material is favorably reduced, and the absorption of the electromagnetic waves in the material is increased.
It should be noted that, along the thickness direction of the gradient layered foamed wave-absorbing material, the mass fractions of the wave-absorbing agent in the multiple foamed wave-absorbing layers increase layer by layer or decrease layer by layer.
Further, in some embodiments, the wave absorbing agent comprises a conductive wave absorbing agent and a magnetic wave absorbing agent.
In some embodiments, the conductive wave absorber comprises multi-walled carbon nanotubes, graphene, or carbon fibers. In some embodiments, the magnetic wave absorber comprises carbonyl iron powder, ferroferric oxide, or ferrite.
Additionally, in some embodiments, the soluble polymeric matrix includes a soluble plastic and a thermoplastic elastomer.
Wherein the soluble polymer matrix comprises polyvinyl chloride, polyvinyl alcohol or polyetherimide; the thermoplastic elastomer includes a thermoplastic polyurethane elastomer, a polyolefin elastomer, or a polypropylene elastomer.
The embodiment provides a plurality of methods for preparing gradient layered foaming wave-absorbing materials. When the gradient layered foam wave-absorbing material is prepared, the composite material of the wave-absorbing agent and the soluble polymer matrix is prepared.
The preparation method of the composite material comprises the following steps:
dissolving the wave absorbing agent in a first organic solvent according to different preset mass proportions and a soluble polymer matrix according to the designed mass fraction of the wave absorbing agent, carrying out ultrasonic treatment to obtain a first mixed solution, adding the first mixed solution into water to precipitate the blend of the wave absorbing agent and the soluble polymer matrix, and then filtering to obtain the blend precipitate of the wave absorbing agent and the soluble polymer matrix; drying the mixture precipitate to obtain the composite material with the wave absorbing agent in gradient distribution. Wherein the drying process is carried out in a forced air drying oven, the drying temperature is 70-100 ℃, and the treatment time is 30-40 h.
In some embodiments, the first organic solvent comprises nitrogen-nitrogen dimethylformamide, dioxane, or xylene. In some embodiments, the soluble polymer matrix is present in an amount of 3 g; in some embodiments, the first organic solvent is 1000 mL.
The wave absorbing agent and the soluble polymer matrix mixed powder are dissolved in a first organic solvent, and ultrasonic treatment is carried out simultaneously, so that the wave absorbing agent and the soluble polymer matrix can be better dispersed to form a uniform first mixed solution. In some embodiments, the power of the ultrasonic treatment is 450-500w, and the treatment time is 20-60 min.
In some embodiments, the first solution is added to water at a mass ratio of 1-2:10, and the blend of wave absorber and soluble polymeric matrix precipitates to be able to settle out in the water due to the excess water. In this embodiment, to enable better precipitation of the blend precipitate, the first mixed solution is slowly poured into the ionized water.
It should be noted that, the mass fractions of the wave-absorbing agent are distributed in a gradient manner layer by layer, which means that the content of the wave-absorbing agent gradually increases or decreases along the thickness direction of the gradient layered foaming wave-absorbing material. The content of the wave absorbing agent is related to the mass fraction of the wave absorbing agent in the composite material, namely, the composite material with different mass fractions of the wave absorbing agent is prepared and then the subsequent operation is carried out.
After the composite material of the wave absorbing agent and the soluble polymer matrix is obtained, the gradient layered foaming wave absorbing material can be obtained only by molding and foaming. The forming and foaming method comprises the following steps:
the first method comprises the following steps: and dissolving the composite material containing the wave absorbers with different mass fractions in a second solvent to obtain a second mixed solution, sequentially cooling the second mixed solution containing the wave absorbers with different mass fractions at the temperature of below-30 ℃ according to a preset sequence so that the second solvent is crystallized into a solid state, the composite material is separated out, and finally obtaining the multilayer foaming wave-absorbing layer with the wave absorbers in the gradient distribution layer by layer. Wherein the second solvent comprises dioxane or water. In the cooling, the cooling may be performed in liquid nitrogen or in a refrigerator.
When the second mixed solution is cooled in liquid nitrogen, the second mixed solution is rapidly led out due to heat, the second solvent in the second mixed solution is crystallized to be changed into a solid state, the wave absorbing agent and the soluble polymer matrix dissolved in the second solvent are separated out due to the reduction of the solubility, and the solid second solvent can form cells in the system because the crystallized second solvent cannot have solute. When the second solvent is completely changed into a solid state, the foaming process is finished.
In one embodiment, cooling the second mixed solution with different wave absorbing agent content in liquid nitrogen or a refrigerator comprises: the method comprises the steps of firstly casting a second mixed solution with the wave absorbing agent content of 2.5g/100ml in a watch glass, then cooling and solidifying to obtain a wave absorbing layer with the highest wave absorbing agent content, then casting the second mixed solution with the wave absorbing agent content of 2g/100ml on the surface of a frozen first layer, then cooling and solidifying to obtain two wave absorbing layers with the wave absorbing agent content of gradient, then casting the second mixed solution with the wave absorbing agent content of 1.5g/100ml on the surface of a frozen second layer, and then cooling and solidifying to obtain three wave absorbing layers with the wave absorbing agent content of gradient.
In addition, when the second mixed solution is cast on the foamed wave-absorbing layer for cooling, the upper layer of the second mixed solution is cast after the lower layer of the foamed wave-absorbing layer is cooled and solidified. And after the second mixed solution of each layer is cooled and solidified, obtaining the multilayer foaming wave-absorbing layer with the wave-absorbing agent content in gradient distribution layer by layer.
Further, the method also comprises the step of freeze drying the plurality of foaming wave-absorbing layers so as to sublimate the second solvent. Wherein the freeze-drying is performed in a freeze-dryer. In some embodiments, the temperature of freeze-drying is-80 ℃ and the drying time is 30-40 h.
Due to sublimation of the second solvent, the bubble structure of the wave absorbing agent mass fraction gradient distribution multi-layer wave absorbing layer can be better retained, so that the gradient layered foaming wave absorbing material with the wave absorbing agent mass fraction gradient distribution is obtained.
It should be noted that in this preparation method, the thickness of each layer can be controlled by the amount of the second mixed solution; the wave absorbing performance of the gradient layered foam wave absorbing material can be adjusted by controlling the pouring layer number; the foaming ratio can be adjusted by adjusting the mixing ratio of the composite material and the second solvent, so that the size and the shape of the gradient layered foaming wave-absorbing material cells can be adjusted.
The second method comprises the following steps: the composite material is paved layer by layer in a mode that the mass fractions of the wave absorbing agents are distributed in a gradient manner, and the paved multilayer composite material is subjected to hot press molding and foaming under the conditions of 160-220 ℃ and 3-6 MPa.
The foaming method includes a chemical foaming method, a physical foaming method or an expandable microsphere foaming method.
Among them, the blowing agent used in the physical foaming method includes low boiling point alkane, chlorofluorocarbon, hydrofluorocarbon, or supercritical fluid (carbon dioxide, nitrogen, water, etc.).
In some embodiments, the multilayer composite material after hot press forming can be put into a high pressure foaming kettle and first CO is used2Air in the foaming kettle is discharged, and then CO is continuously introduced2And raising the temperature to 40-130 ℃, controlling the pressure to be 10-30MPa, and then quickly releasing the pressure, so that the multilayer composite material is foamed to obtain the multilayer foamed wave-absorbing layer.
Further, the foaming agent used in the chemical foaming method includes azodicarbonamide, sodium bicarbonate, ammonium nitrite or azo compounds. When the foaming is performed by the chemical foaming method or the expandable microsphere foaming method, the chemical foaming agent or the expandable microspheres are mixed with the wave absorbing agent and the soluble polymer matrix. Wherein, the addition amount of the chemical foaming agent or the expandable microspheres is 10-15% of the mass of the soluble polymer matrix.
In some embodiments, when the laid multilayer composite material is hot-pressed and molded at the temperature of 160-220 ℃ and under the pressure of 3-6MPa, the chemical foaming agent is heated and decomposed to generate gas foaming, so that the gradient layered foaming wave-absorbing material with the mass fraction of the wave-absorbing agent in gradient distribution is obtained. If expandable microspheres are added, the temperature increase may cause the expandable microspheres to expand, thereby foaming the material.
When foaming is performed by the above method, the thickness and the total thickness of each layer can be controlled by controlling the thickness of the mold frame used in the hot press molding. The wave absorbing performance of the gradient layered foaming wave absorbing material is adjusted through the number of layers of hot press molding.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
Respectively dissolving 1.5g, 2g, 2.5g, 3g and 3.5g of graphene and 30g of thermoplastic polyurethane in 1000mL of nitrogen-nitrogen dimethylformamide to obtain a first mixed solution, placing the dissolved graphene/thermoplastic polyurethane/nitrogen-nitrogen dimethylformamide solution in a probe type ultrasonic generator, and carrying out ultrasonic treatment for 40min under the condition that the ultrasonic power is 480 w. The first solution after ultrasonic treatment was stirred at 60 ℃ for 5 h.
Slowly pouring the stirred graphene/thermoplastic polyurethane/nitrogen-nitrogen dimethylformamide solution into deionized water at a mass ratio of 1:10 so as to precipitate out the graphene/thermoplastic polyurethane blend. Then filtering to obtain the graphene/thermoplastic polyurethane blend precipitate.
And (3) placing the mixture precipitate into a forced air drying oven, and drying for 36 hours at the temperature of 80 ℃ to obtain the graphene/thermoplastic polyurethane composite material.
The graphene/thermoplastic polyurethane composite material with the addition of 1.5g/2g/2.5g/3g/3.5g of graphene is prepared according to the proportion of 8 g: 100mL of the second mixed solution was dissolved in dioxane, and then stirred vigorously at 60 ℃ for 5 hours to obtain second mixed solutions of different concentrations.
And (3) completely dissolved graphene/thermoplastic polyurethane/dioxane solution (second mixed solution) with the addition of 3.5g of graphene is cast in a watch glass, the watch glass is placed on an iron plate, the iron plate is soaked in liquid nitrogen, and the first layer of foaming wave-absorbing layer is obtained after all dioxane is changed into a solid state.
Keeping an iron plate in liquid nitrogen, casting a completely dissolved graphene/thermoplastic polyurethane/dioxane solution (second mixed solution) with the addition of 3g of graphene on the first layer of foaming wave-absorbing layer, and obtaining a second layer of foaming wave-absorbing layer after all dioxane is changed into a solid state.
And (3) keeping the iron plate in liquid nitrogen, casting the completely dissolved graphene/thermoplastic polyurethane/dioxane solution (second mixed solution) with the addition of 2.5g of graphene on the foaming wave-absorbing layer of the second layer, and obtaining a third layer of foaming wave-absorbing layer after all the dioxane is changed into a solid state.
And (3) keeping the iron plate in liquid nitrogen, casting a completely dissolved graphene/thermoplastic polyurethane/dioxane solution (second mixed solution) with the addition of 2g of graphene on the foaming wave-absorbing layer on the third layer, and obtaining the fourth layer of foaming wave-absorbing layer after all dioxane is changed into a solid state.
And (3) keeping the iron plate in liquid nitrogen, casting the completely dissolved graphene/thermoplastic polyurethane/dioxane solution (second mixed solution) with the addition of 1.5g of graphene on the foaming wave-absorbing layer on the fourth layer, and obtaining the fifth layer foaming wave-absorbing layer after all dioxane is changed into a solid state.
And placing the five layers of foaming wave-absorbing layers in a freeze dryer, and drying for 48 hours at the temperature of-80 ℃ to ensure that dioxane is sublimated and the cell structure is reserved, thereby obtaining the gradient layered foaming wave-absorbing material with the graphene content in layer-by-layer gradient distribution.
Example 2
Respectively dissolving 1.5g, 2g, 2.5g, 3g, 3.5g of multi-walled carbon nanotube and 30g of polyolefin elastomer in 1000mL of xylene to obtain a first mixed solution, placing the dissolved multi-walled carbon nanotube/polyolefin elastomer/xylene solution in a probe type ultrasonic generator, and carrying out ultrasonic treatment for 20min under the condition that the ultrasonic power is 500 w. The first solution after ultrasonic treatment was stirred at 55 ℃ for 5 h.
Slowly pouring the stirred multi-wall carbon nano tube/polyolefin elastomer/xylene solution into deionized water at a mass ratio of 1:5 so as to precipitate out the multi-wall carbon nano tube/polyolefin elastomer blend. Then filtering to obtain the multi-wall carbon nano tube/polyolefin elastomer blend precipitate.
And (3) placing the mixture precipitate into a forced air drying oven, and drying for 30 hours at the temperature of 100 ℃ to obtain the multi-walled carbon nanotube/polyolefin elastomer composite material.
Respectively adding the multi-wall carbon nano tube with the addition of 1.5g/2g/2.5g/3g/3.5g into the multi-wall carbon nano tube/polyolefin elastomer composite material according to the proportion of 8 g: 100mL of the second mixed solution was dissolved in water, and then stirred vigorously at 60 ℃ for 5 hours to obtain second mixed solutions of different concentrations.
And (3) casting the completely dissolved multi-wall carbon nano tube/polyolefin elastomer/water solution (second mixed solution) with the addition of 3.5g of multi-wall carbon nano tube in a watch glass, placing the watch glass on an iron plate, soaking the iron plate in liquid nitrogen, and obtaining a first foaming wave-absorbing layer after all water is changed into a solid state.
Keeping an iron plate in liquid nitrogen, casting the multi-wall carbon nano tube/polyolefin elastomer/water (second mixed solution) with the addition of 3g of the multi-wall carbon nano tube completely dissolved on the first foaming wave-absorbing layer, and obtaining a second foaming wave-absorbing layer after all the water is changed into a solid state.
Keeping the iron plate in liquid nitrogen, casting the multi-wall carbon nano tube/polyolefin elastomer/water solution (second mixed solution) with the addition of 2.5g of the multi-wall carbon nano tube completely dissolved on the foaming wave-absorbing layer on the second layer, and obtaining a third layer of foaming wave-absorbing layer after all water is changed into a solid state.
And (3) keeping the iron plate in liquid nitrogen, casting the multiwall carbon nanotube/polyolefin elastomer/water solution (second mixed solution) with the addition of 2g of the multiwall carbon nanotube completely dissolved on the foaming wave-absorbing layer on the third layer, and obtaining the fourth layer of foaming wave-absorbing layer after all water is changed into a solid state.
And (3) keeping the iron plate in liquid nitrogen, casting the multi-walled carbon nanotube/polyolefin elastomer/water solution (second mixed solution) with the addition of 1.5g of the multi-walled carbon nanotube completely dissolved on the foaming wave-absorbing layer on the fourth layer, and obtaining the fifth layer of foaming wave-absorbing layer after all water is changed into a solid state.
And (3) placing the five layers of foaming wave-absorbing layers in a freeze dryer, and drying for 40h at-80 ℃ to ensure that water is sublimated and the cell structure is retained, thereby obtaining the layered foaming wave-absorbing material with the multi-wall carbon nano tube content in layer-by-layer gradient distribution.
Example 3
The preparation method of the gradient layered foam wave-absorbing material in the embodiment 3 is basically the same as that of the gradient layered foam wave-absorbing material in the embodiment 1, and the difference is that in the preparation process, a watch glass is placed in a refrigerator to be cooled and solidified.
Example 4
The embodiment 4 is basically the same as the layered foam wave-absorbing material in the embodiment 1, and the difference is that the graphene/thermoplastic polyurethane composite material with the graphene addition amount of 1.5g/2g/2.5g/3g/3.5g is prepared according to the following proportion of 6 g: 100mL of the second mixed solution was dissolved in dioxane, and then stirred vigorously at 60 ℃ for 5 hours to obtain second mixed solutions of different concentrations.
Example 5
The gradient layered foam wave-absorbing material in the embodiment 5 is basically the same as that in the embodiment 1, except that the addition amount of the graphene is 1g, 1.5g, 2g, 2.5g, 3g, 3.5g and 4g, and the preparation steps are correspondingly modified according to the content of the graphene.
Example 6
Respectively dissolving 1.5g, 2g, 2.5g, 3g, 3.5g of graphene and 30g of thermoplastic polyurethane in 1000mL of nitrogen-nitrogen dimethylformamide to obtain a first mixed solution, placing the dissolved graphene/thermoplastic polyurethane/nitrogen-nitrogen dimethylformamide solution in a probe type ultrasonic generator, and carrying out ultrasonic treatment for 40min under the condition that the ultrasonic power is 480 w. The first solution after ultrasonic treatment was stirred at 60 ℃ for 5 h.
Slowly pouring the stirred graphene/thermoplastic polyurethane/nitrogen-nitrogen dimethylformamide solution into deionized water at a mass ratio of 1:10 so as to precipitate out the graphene/thermoplastic polyurethane blend. Then filtering to obtain the graphene/thermoplastic polyurethane blend precipitate.
And (3) placing the mixture precipitate into a forced air drying oven, and drying for 36 hours at the temperature of 80 ℃ to obtain the graphene/thermoplastic polyurethane composite material.
And paving the graphene/polyurethane composite material layer by layer according to the rule that the content of graphene is gradually increased, and hot-pressing the paved multilayer material at 160 ℃ under the condition of 3 MPa.
Putting the gradient multilayer graphene/polyurethane composite material subjected to hot press molding into a high-pressure foaming kettle, setting the foaming temperature to be 130 ℃ and the pressure to be 20MPa, and firstly using a small amount of CO2Air in the foaming kettle is removed, and CO is continuously introduced2And raising the temperature, keeping the pressure for 2 hours after reaching the required temperature and pressure, and then quickly releasing the pressure, thereby obtaining the gradient layered foaming wave-absorbing material with the wave-absorbing agent mass fraction in gradient distribution.
Example 7
Respectively dissolving 1.5g, 2g, 2.5g, 3g, 3.5g of graphene and 30g of thermoplastic polyurethane, azodicarbonamide (abbreviated as AC in English) with the mass fraction of 10% of the mass of the thermoplastic polyurethane in 1000mL of nitrogen-nitrogen dimethylformamide to obtain a first mixed solution, placing the dissolved graphene/thermoplastic polyurethane/AC/nitrogen-nitrogen dimethylformamide solution in a probe type ultrasonic generator, and carrying out ultrasonic treatment for 40min under the condition that the ultrasonic power is 480 w. The first solution after ultrasonic treatment was stirred at 60 ℃ for 5 h.
Slowly pouring the stirred graphene/thermoplastic polyurethane/AC/nitrogen-nitrogen dimethylformamide solution into deionized water at a mass ratio of 1:10 so as to precipitate out the graphene/thermoplastic polyurethane/AC blend. Then filtering to obtain the graphene/thermoplastic polyurethane/AC blend precipitate.
And (3) placing the mixture precipitate into a forced air drying oven, and drying for 36h at the temperature of 80 ℃ to obtain the azodicarbonamide-containing graphene/thermoplastic polyurethane composite material.
The graphene/thermoplastic polyurethane composite material containing azodicarbonamide is paved layer by layer according to the rule that the mass fraction of graphene is gradually increased, the paved multilayer material is hot-pressed and molded under the conditions of 220 ℃ and 6MPa, and azodicarbonamide is decomposed to generate gas so as to foam to obtain the gradient layered foaming wave-absorbing material with the wave-absorbing agent in gradient distribution.
Example 8
The gradient layered foam wave-absorbing material in the embodiment 8 is basically the same as that in the embodiment 7, and the difference is that azodicarbonamide is replaced by an expandable microsphere foaming agent in the preparation process.
Comparative example 1
The gradient layered foam wave-absorbing material in the comparative example 1 is basically the same as that in the example 1, and the difference is that the graphene content of each layer is the same and is 2.5 g.
Comparative example 2
The gradient layered foam wave-absorbing material of the comparative example 2 is basically the same as that of the example 2, and the difference is that the content of the multi-wall carbon nano tube of each layer is the same and is 2.5g in the preparation process.
Comparative example 3
The comparative example 3 is basically the same as the gradient layered foam wave-absorbing material of the example 3, and the difference is that the graphene content of each layer is the same and is 2.5g in the preparation process.
Comparative example 4
The comparative example 4 is basically the same as the gradient layered foam wave-absorbing material of the example 4, and the difference is that the graphene content of each layer is the same and is 2.5g in the preparation process.
Comparative example 5
The gradient layered foam wave-absorbing material in the comparative example 5 is basically the same as that in the example 5, and the difference is that the graphene content of each layer is the same and is 2.5g in the preparation process.
Comparative example 6
The gradient layered foam wave-absorbing material of the comparative example 6 is basically the same as that of the example 6, and the difference is that the graphene content of each layer is the same and is 2.5g in the preparation process.
Comparative example 7
The comparative example 7 is basically the same as the gradient layered foam wave-absorbing material of the example 7, and the difference is that the graphene content of each layer is the same and is 2.5g in the preparation process.
Comparative example 8
The gradient layered foam wave-absorbing material of the comparative example 8 is basically the same as that of the example 8, and the difference is that the graphene content of each layer is the same and is 2.5g in the preparation process.
Test examples
The wave absorbing properties of the gradient layered foamed wave absorbing material of examples 1-8 and the foamed wave absorbing material of comparative examples 1-8 were tested, and the results are shown in fig. 1-8.
And (4) analyzing results: from the results of fig. 1 to fig. 8, it can be seen that the minimum reflection loss of the gradient layered foamed wave-absorbing material of example 1 is smaller than that of the foamed wave-absorbing material of comparative example 1, and the effective absorption bandwidth of the gradient layered foamed material of example 1 is larger than that of the layered foamed material of comparative example 1. The same conclusion can be drawn by comparing example 2 and comparative example 2, example 3 and comparative example 3, example 4 and comparative example 4, example 5 and comparative example 5, example 6 and comparative example 6, example 7 and comparative example 7, and example 8 and comparative example 8. The wave absorbing effect of the gradient layered foaming wave absorbing material with the wave absorbing agent mass fraction in the gradient distribution is better.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Claims (7)
1. A preparation method of a gradient layered foaming wave-absorbing material is characterized in that the gradient layered foaming wave-absorbing material comprises the following steps: the wave absorbing layer is prepared by foaming a wave absorbing agent and a soluble polymer matrix, and the mass fractions of the wave absorbing agent in the wave absorbing layer are distributed in a gradient manner layer by layer;
the preparation method comprises the following steps:
dissolving the wave absorbing agent and the soluble polymer matrix in a first organic solvent according to different preset mass ratios, performing ultrasonic treatment to obtain a first mixed solution, adding the first mixed solution into water to precipitate a blend of the wave absorbing agent and the soluble polymer matrix, and filtering to obtain a blend precipitate of the wave absorbing agent and the soluble polymer matrix; drying the blend precipitate to obtain the composite material with the wave absorbing agent mass fraction in gradient distribution;
and dissolving the composite material in a second solvent to obtain a second mixed solution, and sequentially cooling the second mixed solution containing the wave absorbers with different mass fractions at the temperature of-30 ℃ according to a preset sequence so that the second solvent is crystallized into a solid state, and the composite material is separated out to obtain the multilayer foaming wave-absorbing layer with the wave absorbers in the gradient distribution layer by layer.
2. The method for preparing the gradient layered foaming wave-absorbing material according to claim 1, wherein the mass fraction of the wave-absorbing agent in the plurality of layers of the foaming wave-absorbing layers is increased layer by layer or decreased layer by layer along the thickness direction of the gradient layered foaming wave-absorbing material.
3. The method for preparing the gradient layered foam wave-absorbing material according to claim 1, wherein the wave-absorbing agent comprises a conductive wave-absorbing agent or a magnetic wave-absorbing agent.
4. The method for preparing the gradient layered foam wave-absorbing material according to claim 3, wherein the conductive wave-absorbing agent comprises multi-walled carbon nanotubes, graphene or carbon fibers; the magnetic wave absorbing agent comprises carbonyl iron powder, ferroferric oxide or ferrite.
5. The method for preparing the gradient layered foaming wave-absorbing material according to claim 1, wherein the soluble polymer matrix comprises soluble plastics and thermoplastic elastomers.
6. The method for preparing the gradient layered foam wave-absorbing material according to claim 1, wherein the first organic solvent comprises nitrogen-nitrogen dimethylformamide, dioxane or xylene; the second solvent comprises dioxane or water.
7. The method for preparing the gradient layered foaming wave-absorbing material according to claim 1, further comprising freeze-drying the plurality of wave-absorbing layers to sublimate the second solvent.
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| CN109648952B (en) * | 2019-01-04 | 2021-05-14 | 北京环境特性研究所 | Gradient type wave-absorbing material with graphene oxide-based structure and preparation method thereof |
| CN111961303B (en) * | 2020-07-11 | 2021-12-14 | 武汉纺织大学 | Gradient microporous broadband wave-absorbing material and supercritical limited foaming preparation method thereof |
| CN111806011A (en) * | 2020-07-21 | 2020-10-23 | 和爱电磁兼容科技(安徽)有限公司 | Electromagnetic wave-absorbing material with oblique incidence performance improvement |
| CN112126089B (en) * | 2020-09-01 | 2023-03-21 | 中国电子科技集团公司第三十三研究所 | Carbon nano composite broadband wave-absorbing gradient structure material and preparation method thereof |
| CN112492865B (en) * | 2020-11-26 | 2024-03-01 | 深圳先进技术研究院 | Electromagnetic shielding foam and preparation method and application thereof |
| CN112831185B (en) * | 2021-02-23 | 2022-09-20 | 中北大学 | Gradient electric conduction-uniform heat conduction dual-function network low-reflection high-absorption electromagnetic shielding polymer composite material |
| CN113910718A (en) * | 2021-08-26 | 2022-01-11 | 四川大学 | Electromagnetic shielding composite material with multilayer gradient isolation network and preparation method thereof |
| CN113853106B (en) * | 2021-10-26 | 2024-03-26 | 浙江工业大学 | Preparation method of electromagnetic shielding foam |
| CN114539617B (en) * | 2022-04-27 | 2022-09-20 | 中北大学 | Green industrial preparation method of ferroferric oxide/reduced graphene oxide and wave-absorbing resin composite material thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101412839A (en) * | 2008-11-18 | 2009-04-22 | 东华大学 | Method for preparing microwave-absorbing composite material from polyacrylonitrile (PAN)-based nano carbon fibre |
| CN101899221A (en) * | 2010-07-02 | 2010-12-01 | 李勇 | Foaming type electromagnetic wave absorption composite material and preparation method thereof |
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| CN101781406A (en) * | 2009-09-25 | 2010-07-21 | 北京中拓机械有限责任公司 | Thermoplastic elastomer skin product and production method thereof |
| CN102875882A (en) * | 2012-10-24 | 2013-01-16 | 青岛鑫三鸿塑胶制品有限公司 | Polyethylene and carbon dioxide extruded micro-foamed product and preparation method thereof |
| GB2544981A (en) * | 2015-12-01 | 2017-06-07 | Tallinn Univ Of Tech | A composite shielding material and a process of making the same |
| KR101936648B1 (en) * | 2015-12-17 | 2019-01-10 | 율촌화학 주식회사 | Methods of manufacturing sheets for electomagnetic waves absorbtion |
| CN106566226B (en) * | 2016-10-21 | 2019-04-02 | 中国科学院宁波材料技术与工程研究所 | A kind of thermoplastic polyurethane/graphene foamed material and its preparation method and application |
| CN107082953A (en) * | 2017-05-05 | 2017-08-22 | 衡水兴洲新材料有限公司 | Inhale ripple, guided wave PP foam material and preparation method thereof |
-
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101412839A (en) * | 2008-11-18 | 2009-04-22 | 东华大学 | Method for preparing microwave-absorbing composite material from polyacrylonitrile (PAN)-based nano carbon fibre |
| CN101899221A (en) * | 2010-07-02 | 2010-12-01 | 李勇 | Foaming type electromagnetic wave absorption composite material and preparation method thereof |
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