CN115093518B - Wave absorber with core-shell structure and preparation method thereof - Google Patents

Wave absorber with core-shell structure and preparation method thereof Download PDF

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CN115093518B
CN115093518B CN202210847652.3A CN202210847652A CN115093518B CN 115093518 B CN115093518 B CN 115093518B CN 202210847652 A CN202210847652 A CN 202210847652A CN 115093518 B CN115093518 B CN 115093518B
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core
iron
wave absorber
wave
shell
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CN115093518A (en
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李姜
何佩瑶
熊英
郭少云
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Sichuan University
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Sichuan University
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
    • C08L51/10—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to inorganic materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F285/00—Macromolecular compounds obtained by polymerising monomers on to preformed graft polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F292/00—Macromolecular compounds obtained by polymerising monomers on to inorganic materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
    • Y02A10/11—Hard structures, e.g. dams, dykes or breakwaters

Abstract

The invention relates to the technical field of wave absorbing materials, and discloses a wave absorbing agent with a core-shell structure and a preparation method thereof, wherein the wave absorbing agent comprises a core body and a shell material coated on the surface of the core body, the core body comprises an iron-based material and a carbon-based material, and the iron-based material comprises an iron-based core material and methyl methacrylate coated on the surface of the iron-based core material; the mass ratio of the core body is as follows: shell = 1-8:2, iron-based material: carbon-based material=1 to 5:1, iron-based core material: methyl methacrylate=2-4:1. According to the core-shell structure wave absorber, the wave absorber base material is processed and modified based on a mechanochemical method, the wave absorbing effect of the wave absorber is enhanced in a base material compounding mode and the like, and a shell structure capable of improving impedance mismatch is formed on the surface of the base material through surface grafting, so that the core-shell structure wave absorber with impedance matching and attenuation characteristics is finally obtained; and the processing process is simple and environment-friendly, and the problem of serious environmental pollution caused by large organic solution dosage in the traditional wave-absorbing material modification processing is avoided.

Description

Wave absorber with core-shell structure and preparation method thereof
Technical Field
The invention relates to the technical field of wave-absorbing materials, in particular to a wave-absorbing agent with a core-shell structure and a preparation method thereof.
Background
With the continuous development of social technology, electronic devices are widely popularized and applied, and electromagnetic wave radiation is also generated. Electromagnetic wave radiation can directly interfere with normal use of other equipment, and also can harm human health, ecological environment and the like. In order to alleviate the damage caused by electromagnetic radiation, there have been proposed wave absorbing materials capable of absorbing electromagnetic waves and dissipating them in the form of heat energy or other forms, or causing the electromagnetic waves to disappear due to interference. The wave-absorbing material mainly comprises a wave-transmitting material and a wave-absorbing agent, wherein the wave-transmitting material is used as a carrier and can endow the material with certain mechanical properties or other properties; and the wave absorber is the main body for losing electromagnetic waves. According to the wearing machineThe wave-absorbing agent can be classified into dielectric loss type wave-absorbing agent and magnetic loss type wave-absorbing agent, and the dielectric loss type wave-absorbing agent comprises carbon material, ag and TiO 2 And the like, and the magnetic loss type wave absorber includes magnetic metal, ferrite, carbonyl iron and the like.
In practical application, the wave-absorbing material with better wave-absorbing performance needs to meet two conditions of impedance matching and attenuation characteristic. However, the dielectric loss type wave absorbers currently used have the following general problems: it is difficult to satisfy both the conditions of impedance matching and strong attenuation, specifically: the content of the conductive filler is increased, so that strong loss of electromagnetic waves can be caused, but meanwhile, impedance mismatch between the surface of the material and air can be caused, and the electromagnetic waves can not enter the material to be absorbed, namely, poor wave absorbing performance is caused. In view of the above problems, the following solutions have been proposed: (1) the dielectric loss type wave absorber and the magnetic loss type wave absorber are compounded, and the problem of impedance mismatch of the material is improved by utilizing the synergistic effect between the dielectric loss type wave absorber and the magnetic loss type wave absorber, but the magnetic loss type wave absorber is easy to oxidize and corrode when exposed to the outside, and the dielectric material is easy to agglomerate to form a conductive channel; (2) the wave-absorbing material is foamed, the impedance matching performance of the wave-absorbing material is improved, meanwhile, the electromagnetic wave is subjected to multiple reflection in the holes to increase loss, and the foamed wave-absorbing material has the defect of overlarge thickness of the wave-absorbing material although the impedance matching and the attenuation characteristics are combined.
Therefore, there is an urgent need for a wave absorber having superior impedance matching, attenuation characteristics, and the like.
Disclosure of Invention
The invention aims to solve the technical problems that:
at present, the existing dielectric loss type wave absorber, magnetic loss type wave absorber and dielectric loss type-magnetic loss type compound wave absorber all have the problems that high impedance matching and high attenuation characteristics can not be realized at the same time, or the thickness of a wave absorbing material is overlarge, products are easy to agglomerate and magnetic ions are easy to corrode when the two properties are considered.
The invention adopts the technical scheme that:
the invention provides a core-shell structure wave absorber, which comprises a core body and a shell material coated on the surface of the core body, wherein the core body comprises an iron-based material and a carbon-based material, and the iron-based material comprises an iron-based core material and methyl methacrylate coated on the surface of the iron-based core material; the mass ratio of the core body is as follows: shell = 1-8:2, iron-based material: carbon-based material=1 to 5:1, iron-based core material: methyl methacrylate=2-4:1.
Preferably, the iron-based material is one or more of ferrite and hydroxy iron.
Preferably, the carbon-based material is one or more of carbon black, carbon nanotubes and graphite.
Preferably, the iron-based material is Fe 3 O 4 The carbon-based material is carbon black, and Fe is calculated according to the mass ratio 3 O 4 : methyl methacrylate: carbon black: shell = 20:7:9:24.
Preferably, the iron-based material further comprises an initiator, the initiator being: methyl methacrylate=1:80-120.
The preparation method of the core-shell structure wave absorber comprises the following steps:
s1, preparing a polymer of an iron-based core material and methyl methacrylate, and marking the polymer as Fe-g-MMA;
s2, uniformly mixing Fe-g-MMA and a carbon-based material to obtain a compound of the Fe-g-MMA and the carbon-based material, and marking the compound as Fe-C;
and S3, adding ACR into the Fe-C, uniformly mixing, and ball milling to obtain the core-shell structure wave absorber.
Preferably, in step S3, the ball milling is performed by a ball mill, wherein the ball milling time is 1.5-2.5h, and the rotation speed of the ball mill is 400-600rpm.
Preferably, the ball milling medium adopts stainless steel balls, and the stainless steel balls are prepared by the following steps of: ball mill material=12 to 18:1.
Preferably, the stainless steel balls have a diameter of 4-10mm.
Preferably, the preparation of the polymer of the iron-based core material and methyl methacrylate comprises the following steps:
s1.1, purifying methyl methacrylate;
s1.2, premixing the purified methyl methacrylate and an iron-based core material according to a mass ratio to obtain a premix;
s1.3 adding an initiator into the premix, mixing and ball milling for 5 hours.
The invention adopts the technical mechanism that:
the high polymer material is used for wrapping the wave absorber base material with wave absorbing performance, so that the core-shell structure wave absorber with good performances such as strong chemical stability and easy realization of broadband absorption is formed, and the problem of poor comprehensive performance of the existing wave absorber is solved.
Specifically, the dielectric loss type wave absorber and the magnetic loss type wave absorber are compounded, and after the dielectric loss type wave absorber and the magnetic loss type wave absorber are combined, a synergistic effect is exerted, so that the impedance matching performance of the material can be improved. Based on the mode of compounding and synergy of the wave absorber base materials, the surface of the compounded composite particles is wrapped with an insulating elastic polymer material to form the wave absorber with a core-shell structure of hard core-soft shell, so that impedance matching is improved, interface polarization loss is introduced, and wave absorbing performance is improved.
Among them, in the dielectric loss type wave absorber, carbon materials have advantages of light weight, oxidation resistance, thermal stability, high dielectric loss, etc., such as Carbon Black (CB), carbon nanotubes, etc., and are widely used in polymer composite wave absorbing materials; fe (Fe) 3 O 4 The composite material has the characteristics of low cost, high magnetic loss and the like, is also commonly used as a magnetic loss type wave absorber, is compounded with a dielectric loss type wave absorber, and can widen the absorption bandwidth. The CB and the Fe are adopted 3 O 4 Compounding to obtain Fe with high impedance matching performance 3 O 4 -CB composite particles.
Acrylic ester (ACR) is a polymer material with low dielectric constant, and the ACR is used for wrapping the magnetic particles Fe which are easy to oxidize and corrode 3 O 4 Fe compounded with high-dielectric wave absorber CB 3 O 4 -CB composite particles: on one hand, the problem that CB particles are mutually overlapped to form a conductive network so as to improve impedance mismatch between the surface of the material and air can be avoided; on the other hand can be to Fe 3 O 4 Playing a role in protection. In addition, ACR toolHas high elasticity and can improve inorganic particles CB and Fe 3 O 4 Compatibility with the polymer matrix, thereby improving the mechanical property of the composite wave-absorbing material.
Also, because CB is an oily material, fe 3 O 4 Is an aqueous material, thus, in the process of mixing CB with Fe 3 O 4 Before compounding, fe is firstly mixed with 3 O 4 And (3) carrying out modification processing: to Fe 3 O 4 Surface introduction of methyl methacrylate (Methyl methacrylate, MMA) by grafting to enhance Fe 3 O 4 Compatibility with ACR, so that ACR can be more effectively wrapped on the surface thereof; meanwhile, MMA is adopted to wrap Fe 3 O 4 Can slow down magnetic ion Fe 3 O 4 Oxidation process of the surface.
The beneficial effects of the invention are as follows:
according to the core-shell structure wave absorber, the wave absorber base material is processed and modified based on a mechanochemical method, the wave absorbing effect of the wave absorber is enhanced in a base material compounding mode and the like, and a shell structure capable of improving impedance mismatch is formed on the surface of the base material through surface grafting, so that the core-shell structure wave absorber with impedance matching and attenuation characteristics is finally obtained; and the processing process is simple and environment-friendly, and the problem of serious environmental pollution caused by large organic solution dosage in the traditional wave-absorbing material modification processing is avoided.
Drawings
Fig. 1 is a schematic structural view of a core-shell structure wave absorber in example 1;
FIG. 2 is Fe in example 1 3 O 4 -g-MMA wave absorption profile;
FIG. 3 is a graph showing the absorption properties of FC3@A4 in example 1;
FIG. 4 is a graph of the wave-absorbing properties of FC3@A2 in example 2;
FIG. 5 is a graph of the wave-absorbing properties of FC3@A6 in example 3;
FIG. 6 is a graph of the absorption properties of FC1@A4 in example 4;
FIG. 7 is a graph of the absorption properties of FC5@A4 in example 5;
FIG. 8 is a graph of the wave-absorbing properties of PT5@A5 in example 6;
FIG. 9 is a graph of the wave-absorbing properties of C@A4 in comparative example 1;
fig. 10 is a graph of the wave-absorbing performance of FC in comparative example 2.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The invention provides a wave absorber with a core-shell structure, which comprises a core body and a shell material coated on the surface of the core body, wherein the core body comprises an iron-based material and a carbon-based material, and the iron-based material comprises an iron-based core material and methyl methacrylate coated on the surface of the iron-based core material; the mass ratio of the core body is as follows: shell = 1-8:2, iron-based material: carbon-based material=1 to 5:1, iron-based core material: methyl methacrylate=2-4:1.
Wherein the iron-based material is one or more of ferrite and hydroxyl iron; the carbon-based material is one or more of carbon black, carbon nano tube and graphite; the iron-based material further comprises an initiator, wherein the initiator comprises the following components in percentage by mass: methyl methacrylate=1:80-120.
The invention also provides a preparation method of the core-shell structure wave absorber, which comprises the following steps:
s1, preparing a polymer of an iron-based core material and methyl methacrylate, and marking the polymer as Fe-g-MMA;
s2, uniformly mixing Fe-g-MMA and a carbon-based material to obtain a compound of the Fe-g-MMA and the carbon-based material, and marking the compound as Fe-C;
s3, adding ACR into the Fe-C, uniformly mixing, and ball milling to obtain the core-shell structure wave absorber;
wherein, the polymer for preparing the iron-based core material and the methyl methacrylate in the S1 comprises the following steps:
s1.1, purifying methyl methacrylate;
s1.2, premixing the purified methyl methacrylate and an iron-based core material according to a mass ratio to obtain a premix;
s1.3 adding an initiator into the premix, mixing and ball milling for 5 hours.
In the invention, a common ball mill can be adopted for ball milling, the ball milling time is controlled to be 1.5-2.5 hours, and the rotating speed of the ball mill is 400-600rpm; wherein, the ball milling medium adopts stainless steel balls with the diameter of 4-10mm, and the stainless steel balls are prepared according to the mass ratio: ball mill material=12 to 18:1.
In the invention, the purified methyl methacrylate and Fe are adopted first 3 O 4 Mixing to obtain oily polymer Fe 3 O 4 -g-MMA, allowing direct binding to ACR; fe is then added to 3 O 4 Mixing and compounding g-MMA and carbon black to obtain a compound product Fe 3 O 4 CB improves the impedance matching by coupling and has magnetic Fe 3 O 4 -g-MMA also has a magnetic loss effect on electromagnetic waves; backward Fe 3 O 4 Introducing ACR on the surface of CB to wrap ACR on the compound product Fe 3 O 4 -CB surface, the final wave absorber being obtained comprising Fe 3 O 4 -g-MMA@ACR, CB@ACR and Fe 3 O 4 -g-MMA-CB@ACR, and the three mixed core-shell structured wave absorbers are prepared from ACR with exposed surface or Fe without ACR coating 3 O 4 -interfacial polarization occurs between g-MMA or CB, allowing electromagnetic waves to be absorbed to a greater extent after multiple reflection; can avoid the formation of conductive network among carbon black particles to improve impedance mismatch, and slow down Fe 3 O 4 Is a surface oxidation process of (a).
< example >
Example 1
The embodiment provides a core-shell structure wave absorber, which comprises a core body and a shell material (the structure is shown in figure 1) coated on the surface of the core body; comprises 10g by mass of Fe 3 O 4 4.5g of carbon black, 3.5g of methyl methacrylate and 12g of ACR, and 0.035g of potassium persulfate. Wherein the iron-based core material is Fe 3 O 4 The carbon-based material is carbon black, the shell material is ACR, and the initiator is potassium persulfate.
The embodiment also provides a preparation method of the core-shell structure wave absorber, which is characterized by comprising the following steps:
s1 preparation of Fe 3 O 4 Polymers with methyl methacrylate, denoted Fe 3 O 4 -g-MMA；
S2 Fe 3 O 4 mixing-g-MMA with carbon black to obtain Fe 3 O 4 -g-MMA and carbon black, denoted as Fe 3 O 4 -CB；
S3 to Fe 3 O 4 Adding ACR into CB, mixing uniformly, putting into a low-temperature planetary ball mill, and ball milling at room temperature to obtain a core-shell structure wave absorber FC3@A4;
wherein Fe is prepared 3 O 4 A polymer with methyl methacrylate comprising the steps of:
s1.1 purifying methyl methacrylate:
(1) preparing 0.05g/m NaOH aqueous solution;
(2) weighing 200mLMMA, pouring into a separating funnel, weighing 40mLNaOH aqueous solution, pouring into the separating funnel, oscillating, standing until layering, discarding the lower red washing liquid, and repeating until the lower washing liquid is colorless; washing with deionized water until the lower layer washing liquid is neutral;
(3) pouring the MMA supernatant washed in the step (2) into a beaker from an upper opening, adding 20g of anhydrous sodium sulfate, standing for half an hour, and filtering by using a triangular funnel to obtain MMA from which water is removed;
(4) finally, the mixture is distilled under reduced pressure.
S1.2 mixing purified methyl methacrylate with Fe 3 O 4 Premixing according to a mass ratio to obtain a premix;
s1.3, adding the premix and potassium persulfate into a low-temperature planetary ball mill together, and ball milling for 5 hours at room temperature.
In the step S3, a low-temperature ball mill is adopted for ball milling, the ball milling time is 2 hours, the rotating speed of the ball mill is 500rpm, a ball milling medium adopts stainless steel balls with the diameter of 6.5mm, and the ball milling material is 13.535g by mass and the weight of the stainless steel balls is 203.025g.
Fe is measured by a vector network analyzer by adopting a coaxial method 3 O 4 Wave-absorbing Property of g-MMA (as shown in FIG. 2), minimum reflection loss RL min Is-20.01 dB, and the effective absorption bandwidth is 2.76GHz; and the absorption properties of FC3@A4 (as shown in FIG. 3), the lowest reflection loss RL min The effective absorption bandwidth is 4.93GHz at-34.37 dB. Wherein, when measuring the wave absorbing performance, the thickness of the sample of the object to be measured is 2.2mm, fe 3 O 4 The loading of g-MMA, FC3@A4 in paraffin was 20% by weight.
Example 2
As shown in FIG. 4, this embodiment differs from embodiment 1 in that this embodiment provides a core-shell structured wave absorber comprising 10g by mass of Fe 3 O 4 4.5g of carbon black, 3.5g of methyl methacrylate and 4.5g of ACR, and 0.035g of potassium persulfate, a core-shell structured wave absorber FC3@A2 was finally obtained, and the wave absorbing properties of FC3@A2 were measured (as shown in FIG. 4), with the lowest reflection loss RL min The effective absorption bandwidth is-21.76 dB and 4.45GHz.
Example 3
As shown in FIG. 5, this embodiment differs from embodiment 1 in that this embodiment provides a core-shell structured wave absorber comprising 10g by mass of Fe 3 O 4 4.5g of carbon black, 3.5g of methyl methacrylate and 27g of ACR, and 0.035g of potassium persulfate, a core-shell structured wave absorber FC3@A6 was finally produced, and the wave absorbing properties of FC3@A6 (as shown in FIG. 5) were measured, with the lowest reflection loss RL min The effective absorption bandwidth is 6.39GHz at-18.10 dB.
Example 4
As shown in FIG. 6, this embodiment differs from embodiment 1 in that this embodiment provides a core-shell structured wave absorber comprising, by mass, 6.67g of Fe 3 O 4 9g of carbon black, 2.33g of methyl methacrylate, 12g of ACR and 0.0233g of potassium persulfate, and finally obtaining the core-shell structured wave absorber FC1@A4, and measuring the wave-absorbing property of FC1@A4 (as shown in FIG. 6), the minimum reflection loss RL min The effective absorption bandwidth is 4.41GHz at-18.12 dB.
Example 5
As shown in FIG. 7, this embodiment differs from embodiment 1 in that this embodiment provides a core-shell structured wave absorber comprising 11.11g of Fe by mass 3 O 4 3g of carbon black, 3.89g of methyl methacrylate, 12g of ACR and 0.0389g of potassium persulfate, and finally obtaining the core-shell structure wave absorber FC5@A4, and measuring the wave absorbing performance of FC5@A4 (shown in FIG. 7), the minimum reflection loss RL min The effective absorption bandwidth is 4.81GHz at-38.60 dB.
Example 6
As shown in FIG. 8, this example is different from example 1 in that this example provides a core-shell structured wave-absorbing agent comprising, by mass, 10g of iron carbonyl, 2.6g of CNT, 3g of methyl methacrylate and 15.6g of ACR, and 0.03g of potassium persulfate, finally producing a core-shell structured wave-absorbing agent PT5@A5, and measuring the wave-absorbing performance of PT5@A5 (as shown in FIG. 8), the minimum reflection loss RL min The effective absorption bandwidth is 6.21GHz at-20.08 dB.
Comparative example
Comparative example 1
The present comparative example differs from example 1 in that the core body includes only one of the iron-based material or the carbon-based material. Specifically, the core-shell structure wave-absorbing material C@A4 is finally prepared by comprising 4.5g of carbon black and 3g of ACR, and the wave-absorbing performance (shown in FIG. 9) is measured by adopting the same method, so that the minimum reflection loss RL is obtained min The effective absorption bandwidth is-11.50 dB and 0.26GHz. The comparison results can be found that: the wave-absorbing properties of the wave-absorbing agent prepared in this comparative example were significantly weaker than those of the wave-absorbing agent of example 1.
Comparative example 2
The present comparative example is different from example 1 in that the wave absorber is only a mixture including an iron-based material and a carbon-based material, and does not include a shell material coated on the surface of the mixture. In particular, bagsInclude 10g Fe 3 O 4 And 4.5g of carbon black are commonly blended to obtain a composite wave-absorbing agent FC, and the wave-absorbing performance (shown in FIG. 10) is also measured by adopting the same method, and the minimum reflection loss RL is measured min The effective absorption bandwidth is 0GHz at-8.37 dB. The comparison results can be found that: the wave absorbing performance of the wave absorbing agent prepared in the comparative example is obviously weaker than that of the wave absorbing agent in the example 1, and the iron-based material or the carbon-based material is easy to be damaged and lose efficacy in the use process, so that the absorption of electromagnetic waves can not be realized.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. The wave absorber with the core-shell structure is characterized by comprising a core body and a shell material coated on the surface of the core body, wherein the core body comprises an iron-based material and a carbon-based material, and the iron-based material comprises an iron-based core material and methyl methacrylate coated on the surface of the iron-based core material;
the mass ratio of the core body is as follows: shell = 1-8:2, iron-based material: carbon-based material=1 to 5:1, iron-based core: methyl methacrylate = 2-4:1;
the preparation method of the core-shell structure wave absorber comprises the following steps:
s1, preparing a polymer of an iron-based core material and methyl methacrylate, and marking the polymer as Fe-g-MMA;
s2, uniformly mixing Fe-g-MMA and a carbon-based material to obtain a compound of the Fe-g-MMA and the carbon-based material, and marking the compound as Fe-C;
and S3, adding ACR into the Fe-C, uniformly mixing, and ball milling to obtain the core-shell structure wave absorber.
2. The core-shell structured wave absorber of claim 1 wherein the iron-based core material is one or more of ferrite and hydroxyiron.
3. The core-shell structured wave absorber of claim 2 wherein the carbon-based material is one or more of carbon black, carbon nanotubes, graphite.
4. The core-shell structured wave absorber according to claim 3, wherein the iron-based core material is Fe 3 O 4 The carbon-based material is carbon black, and Fe is calculated according to the mass ratio 3 O 4 : methyl methacrylate: carbon black: shell = 20:7:9:24.
5. The core-shell structured wave absorber of claim 1 wherein the iron-based material further comprises an initiator, the initiator being in mass ratio: methyl methacrylate=1:80-120.
6. The core-shell structured wave absorber according to claim 1, wherein in step S3, ball milling is performed by using a ball mill for a time period of 1.5 to 2.5 hours at a rotational speed of 400 to 600rpm.
7. The core-shell structured wave absorber according to claim 6, wherein the ball milling medium is stainless steel balls, and the mass ratio of the stainless steel balls is as follows: ball milling material=12-18:1.
8. The core-shell structured wave absorber of claim 7 wherein the stainless steel balls have a diameter of 4-10mm.
9. The core-shell structured wave absorber of claim 1 wherein preparing a polymer of an iron-based core material and methyl methacrylate comprises the steps of:
s1.1, purifying methyl methacrylate;
s1.2, premixing the purified methyl methacrylate and an iron-based core material according to a mass ratio to obtain a premix;
s1.3 adding an initiator into the premix, mixing and ball milling for 5 hours.
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