A wave-absorbing composite material, a preparation method and application thereof

Abstract

This invention belongs to the field of polymer composite materials technology, specifically disclosing a microwave absorbing composite material, its preparation method, and its applications. The microwave absorbing composite material uses polycarbonate / acrylonitrile-butadiene-styrene copolymer as the matrix and includes sheet-like carbonyl iron, whisker carbon nanotubes, antioxidants, flame retardants, and lubricants. Through the synergistic effect of whisker carbon nanotubes and sheet-like carbonyl iron, this microwave absorbing composite material achieves excellent broadband microwave absorption performance at an extremely thin thickness (1.5 mm): the effective absorption bandwidth (reflection loss ≤ -10 dB) covers 10.48~17.68 GHz, and more than 90% of the single effective absorption bandwidth reaches 7.2 GHz. The preparation process of this invention is simple, and the resulting microwave absorbing composite material can significantly improve its electromagnetic compatibility and anti-interference ability, showing broad application prospects in electronic devices such as laptops, mobile phones, and routers that require lightweight and thin designs.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and in particular to a microwave absorbing composite material, its preparation method, and its application. Background Technology

[0002] With the widespread adoption of 5G, the Internet of Things, and high-frequency electronic devices, electromagnetic pollution and interference problems are becoming increasingly serious. Developing lightweight materials that can achieve efficient broadband absorption within a limited thickness, especially in millimeter-wave bands (such as the Ku band, 12-18 GHz), has become a key requirement in the fields of electronic packaging, consumer electronics, and defense stealth.

[0003] Currently, traditional microwave absorbing composite materials mainly rely on a single electrical or magnetic loss mechanism. While electrical loss materials, such as ordinary carbon nanotubes and graphene, have advantages like low density and high conductivity, their excessively high complex permittivity easily leads to impedance mismatch, causing strong reflection of electromagnetic waves at the material surface, making it difficult for them to penetrate and be consumed internally. Magnetic loss materials, such as carbonyl iron powder, are limited by the Snooker limit, with a sharp drop in permeability above 10 GHz, and suffer from drawbacks such as excessive density, susceptibility to oxidation and corrosion, and excessively thick matching thickness. Although existing technologies attempt to combine carbon materials with magnetic powders, when the thickness is compressed to around 1.5 mm, the absorption bandwidth often narrows significantly, making it difficult to achieve both extremely thin thickness and efficient coupling across frequency bands (e.g., 10.48 GHz to 17.68 GHz).

[0004] The core challenge in achieving ultrathin, broadband electromagnetic wave absorbing materials lies in effectively extending the equivalent propagation path of electromagnetic waves within the material under finite thickness conditions. This requires achieving good impedance matching to reduce interface reflection while simultaneously constructing a multi-scale, multi-mechanism synergistic energy dissipation system. Existing mixing processes often result in disordered distribution of functional fillers within the polymer matrix, making it difficult to form an effective charge transport network and magnetic polarization centers. In particular, ordinary one-dimensional nanomaterials are prone to agglomeration during the composite process, making it impossible to construct fine bridging structures between magnetic particles, leading to insufficient interface polarization loss. Furthermore, high-concentration fillers in absorbing materials can lead to poor processing flowability of the composite material, and the metal components are prone to oxidation and degradation under high-frequency service environments. Simultaneously, the oxidation or structural degradation of both metal and magnetic components under high-frequency service environments cause electromagnetic parameters to change over time, affecting the long-term stability and reliability of the material and limiting its application in harsh industrial environments with high temperature, humidity, or flame retardancy requirements.

[0005] Therefore, how to overcome the thickness-bandwidth limitation by constructing a cross-scale magnetoelectric cooperative network under extremely thin matching thickness, achieve effective absorption of ultra-wideband coverage from 10.48 GHz to 17.68 GHz, and simultaneously solve the oxidation stability, flame retardancy safety and processing dispersion of composite materials in complex service environments, is a key technical problem that urgently needs to be solved in the field of microwave absorbing materials. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned shortcomings of the prior art by providing a microwave absorbing composite material, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A first aspect of the present invention is to provide a microwave absorbing composite material, which is formed by melt blending the following raw materials in parts by weight: Polycarbonate / acrylonitrile-butadiene-styrene copolymer: 50 parts; Flake iron carbonyl: 10-50 parts; Whisker carbon nanotubes: 0.5-5 parts; Antioxidant: 0.5-3 parts; Flame retardant: 0.5-3 parts; Lubricant: 0.5-3 parts; The mass ratio of the whisker carbon nanotubes to the sheet-like carbonyl iron is (1.5~2.5):50.

[0008] Furthermore, the polycarbonate / acrylonitrile-butadiene-styrene copolymer has a melt index of not less than 22 g / min under conditions of 220°C and 10 kg pressure.

[0009] Furthermore, the particle size of the flake-shaped carbonyl iron is 1-5 μm.

[0010] Furthermore, the whisker carbon nanotubes have an inner diameter of 2-5 nm, an outer diameter of 20-200 nm, and a length of 1-15 μm.

[0011] Furthermore, the antioxidant is selected from one or more of tetrakis(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester.

[0012] Furthermore, the flame retardant is zinc borate and / or bisphenol A bis(diphenyl phosphate).

[0013] Furthermore, the lubricant is calcium stearate and / or zinc stearate.

[0014] Furthermore, when the matching thickness of the absorbing composite material is 1.5 mm, its effective absorption frequency band with a reflection loss ≤ -10 dB covers 10.48 GHz to 17.68 GHz, and the effective absorption bandwidth reaches 7.2 GHz.

[0015] A second aspect of the present invention is to provide a method for preparing the aforementioned microwave absorbing composite material, comprising the following steps: The polycarbonate / acrylonitrile-butadiene-styrene copolymer, sheet-like carbonyl iron, whisker carbon nanotubes, antioxidants, flame retardants and lubricants are placed in a high-speed mixer and mixed at a speed of 500~2000 r / min. The mixed materials are added to an internal mixer, melt-blended at a processing temperature of 220-240℃, cooled, and granulated to obtain the microwave absorbing composite material.

[0016] A third aspect of the present invention is to provide the application of the aforementioned absorbing composite material in electromagnetic interference suppression or band absorption of electronic devices, including laptops, mobile phones, or routers.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) The microwave absorbing composite material provided by the present invention achieves effective absorption (reflection loss ≤ -10 dB) in a wide frequency range of 10.48~17.68 GHz with a matching thickness of only 1.5 mm by combining three-dimensional whisker carbon nanotubes with sheet carbonyl iron. Its maximum single effective absorption bandwidth of more than 90% can reach 7.2 GHz, perfectly covering key communication frequency bands such as Ku band, effectively solving the common problem of narrow bandwidth and weak absorption of thin microwave absorbing materials in high frequency bands above 10 GHz.

[0018] (2) This invention utilizes the high aspect ratio and structural rigidity of whisker carbon nanotubes to construct a unique electronic bridging network between sheet-like carbonyl iron particles. The two work together to achieve a "magnetic-electric" double loss mechanism and optimize the impedance matching of the material, thereby significantly broadening the absorption bandwidth.

[0019] (3) This invention achieves a dynamic balance between complex permittivity and complex permeability by adjusting the ratio of whisker carbon nanotubes to sheet carbonyl iron. This specific impedance matching design ensures that electromagnetic waves can penetrate the material to the maximum extent, and by utilizing the 1 / 4 wavelength destructive interference principle and multiple scattering mechanism, it precisely induces ultra-wideband absorption peak coupling at a specific thickness node of 1.5 mm, thereby obtaining an extremely wide effective absorption band.

[0020] (4) The process compatibility provided by the present invention is good: the material is based on easily processed PC / ABS, and can be mass-produced using mature plastic processing equipment (mixing, twin-screw extrusion, injection molding), which is convenient to integrate with existing electronic equipment manufacturing processes and has a high industrialization prospect.

[0021] (5) The microwave absorbing composite material provided by the present invention has excellent microwave absorbing performance while maintaining the good mechanical strength, flame retardancy and dimensional stability of PC / ABS, and can be directly used as a structural and functional integrated component. Attached Figure Description

[0022] Figure 1 The reflection loss diagram is for the composite material in Comparative Example 1. Figure 2 The reflection loss diagram is for the composite material in Comparative Example 2. Figure 3 The diagram shows the reflection loss of the composite material in Example 1. Figure 4 SEM image of whisker carbon nanotubes; Figure 5 This is a SEM cross-sectional view of the composite material from Example 1. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the specific embodiments and accompanying drawings are described in further detail below. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0024] The core concept of this invention lies in constructing a cross-scale, asymmetric three-dimensional electromagnetic synergistic network to overcome the physical bottleneck of traditional single-component absorbing materials with wide bandwidth and narrow absorption at ultra-thick thicknesses. The inventors considered that one-dimensional whisker carbon nanotubes have extremely high aspect ratios, providing a one-dimensional electron transport path, while two-dimensional sheet-like carbonyl iron possesses excellent shape anisotropy and magnetic loss characteristics. Specifically, using sheet-like carbonyl iron as the magnetic polarization unit, and utilizing the "electron bridging" effect formed between whisker carbon nanotubes, a discontinuous but high-frequency sensitive conduction-polarization composite network is established within the polymer matrix. This concept aims to utilize the rigidity of the whisker structure to prevent excessive agglomeration of the carbon component, thereby maintaining rational impedance matching characteristics.

[0025] To achieve an ultra-thin design of 1.5 mm, this invention employs a strategy to enhance the high-frequency magnetic loss of the material. This is achieved by introducing sheet-like carbonyl iron to overcome the snooker limit of spherical powders and increase the magnetic natural resonance frequency. Next, whisker-shaped carbon nanotubes are introduced to adjust the dielectric response of the system, utilizing their interfacial polarization and microwave conduction loss capabilities to achieve deep dissipation of electromagnetic wave energy. Finally, the development process comprehensively considers electromagnetic properties, material mechanics, and processability. Through systematic modification with antioxidants, flame retardants, and lubricants, a high-performance composite material with industrial application value is prepared.

[0026] During the research and development process, the inventors discovered that simple physical mixing leads to severe impedance mismatch. Through ratio optimization, they found that whisker carbon nanotubes and sheet-like carbonyl iron, at a specific ratio, induce magnetoelectric coupling resonance, which is key to achieving an ultra-wide bandwidth of 7.2 GHz. When the sheet-like filler and nano-carbon materials are filled at high concentrations, the viscosity of the system increases exponentially, easily leading to agglomeration and significant shifts in absorption performance. By introducing specific lubricants and modification processes, the challenge of uniform spatial distribution of multi-scale fillers in the polymer matrix was successfully solved. Furthermore, due to its large specific surface area, sheet-like carbonyl iron is easily oxidized during processing and service, resulting in a decrease in magnetic permeability. By screening suitable antioxidant systems during the research and development process, the active surface of the metal powder was effectively protected, ensuring long-term stability of the absorption band in complex environments, ultimately achieving a deep synergy between performance and reliability.

[0027] The absorbing composite material provided by this invention can be used for electromagnetic interference suppression or band absorption in electronic devices, particularly laptops, mobile phones, and routers. These consumer electronics products have extremely limited internal space, placing stringent requirements on the thickness of the absorbing material (typically <2.0 mm). Furthermore, modern communication devices cover multiple frequency bands (such as Wi-Fi 6E and 5G high-frequency bands). The absorbing composite material of this invention can cover 10.48~17.68 GHz with a thickness of only 1.5 mm, solving the interference shielding problem for miniaturized devices across a wide frequency range.

[0028] The invention has now been generally described, and will be more readily understood by referring to the following embodiments, which are provided by way of example and not by way of limitation.

[0029] Example 1 This embodiment 1 provides a microwave absorbing composite material and its preparation method, the preparation method of which is as follows: According to the formula in Table 1, each component is placed in a high-speed mixer and mixed at a speed of 1000 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 240 ℃ and a speed of 1000 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0030] Table 1. Formulation of the microwave absorbing composite material in Example 1.

[0031]

[0032] Example 2 This embodiment 2 provides a microwave absorbing composite material and its preparation method, the preparation method of which is as follows: According to the formula in Table 2, each component is placed in a high-speed mixer and mixed at a speed of 500 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 220 ℃ and a speed of 2000 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0033] Table 2. Formulation of the microwave absorbing composite material in Example 2.

[0034]

[0035] Example 3 This embodiment 3 provides a microwave absorbing composite material and its preparation method, the preparation method of which is as follows: According to the formula in Table 3, each component is placed in a high-speed mixer and mixed at a speed of 2000 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 240 ℃ and a speed of 500 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0036] Table 3. Formulation of the microwave absorbing composite material in Example 3.

[0037]

[0038] Example 4 This embodiment 4 provides a microwave absorbing composite material and its preparation method, the preparation method of which is as follows: According to the formula in Table 4, each component is placed in a high-speed mixer and mixed at a speed of 1500 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 230 ℃ and a speed of 1500 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0039] Table 4. Formulation of the microwave absorbing composite material in Example 4.

[0040]

[0041] Example 5 According to the formula in Table 5, each component is placed in a high-speed mixer and mixed at a speed of 2000 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 225 ℃ and a speed of 2000 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0042] Table 5. Formulation of the microwave absorbing composite material in Example 5.

[0043]

[0044] Example 6 According to the formula in Table 6, each component is placed in a high-speed mixer and mixed at a speed of 1500 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 240 ℃ and a speed of 1500 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0045] Table 6. Formulation of the microwave absorbing composite material in Example 6.

[0046]

[0047] Example 7 According to the formula in Table 7, each component is placed in a high-speed mixer and mixed at a speed of 2000 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 225 ℃ and a speed of 2000 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0048] Table 7. Formulation of the microwave absorbing composite material in Example 7.

[0049]

[0050] Example 8 According to the formula in Table 8, each component is placed in a high-speed mixer and mixed at a speed of 1000 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 240 ℃ and a speed of 2000 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0051] Table 8. Formulation of the microwave absorbing composite material of Example 8.

[0052]

[0053] Example 9 According to the formula in Table 9, each component is placed in a high-speed mixer and mixed at a speed of 1500 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 230 ℃ and a speed of 2000 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0054] Table 9. Formulation of the microwave absorbing composite material of Example 9.

[0055]

[0056] Comparative Example 1 Comparative Example 1 provides a microwave absorbing composite material and its preparation method, which is as follows: According to the formula in Table 10, the components are placed in a high-speed mixer and mixed at a speed of 1000 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 240 ℃ and a speed of 1000 r / min. After cooling and granulation, the microwave absorbing composite material is obtained. Table 10. Formulation of the microwave absorbing composite material of Comparative Example 1.

[0057]

[0058] Comparative Example 2 Comparative Example 2 provides a microwave absorbing composite material and its preparation method, which is as follows: According to the formula in Table 11, each component is placed in a high-speed mixer and mixed at a speed of 1000 r / min. The mixed material is then added to an internal mixer and melt-blended at a processing temperature of 240 ℃ and a speed of 1000 r / min. After cooling and granulation, the microwave absorbing composite material is obtained.

[0059] Table 11. Formulation of the microwave absorbing composite material in Comparative Example 2.

[0060]

[0061] Performance testing: Absorption performance: The electromagnetic parameters (complex permittivity and complex permeability) of the sample were tested in the frequency range of 2-18 GHz using a vector network analyzer (Agilent E5071C) and a coaxial / waveguide test system. The reflection loss at different thicknesses was calculated using formulas (1) and (2).

[0062] (1) (2) In the formula: The complex permittivity is... For complex permeability, For frequency, At the speed of light, d Z represents the material thickness. in Z is the input impedance, and Z0 is the impedance in free space.

[0063] Figure 1This is a reflection loss diagram of the composite material in Comparative Example 1. Figure 2 This is the reflection loss diagram of the composite material in Comparative Example 2. Figure 3 This is a reflection loss diagram of the composite material in Example 1, simulating the reflectivity of the absorbing coating at different thicknesses. Figure 1 As shown, under a matching thickness of 1.5 mm, the composite material prepared in Comparative Example 1 exhibits significant electromagnetic wave absorption performance. Its effective absorption band with a reflection loss ≤ -10 dB covers 11.84 GHz to 14.88 GHz, and its absorption bandwidth reaches 3.04 GHz. This absorption performance is mainly attributed to the magnetic loss mechanism contributed by the sheet-like carbonyl iron component. When carbon nanotubes are added, they form a composite loss system with the sheet-like carbonyl iron. At a matching thickness of 1.5 mm, the prepared composite material achieves an effective absorption bandwidth of 4.48 GHz (covering the 8.00-12.48 GHz frequency band) with a reflection loss ≤ -10 dB. This performance is significantly better than Comparative Example 1 (bandwidth 3.04 GHz), which relies solely on the magnetic loss of the sheet-like carbonyl iron, demonstrating that the dielectric loss introduced by the carbon nanotubes and the original magnetic loss produce an effective synergistic enhancement effect. To further improve the microwave absorption performance of the composite material, this invention introduces whisker-shaped carbon nanotubes. The composite material prepared in Example 1, with a matching thickness of 1.5 mm, exhibits an effective absorption bandwidth covering 10.48 GHz to 17.68 GHz with a reflection loss ≤ -10 dB, and an absorption bandwidth of 7.2 GHz. Compared to the composite material with added ordinary carbon nanotubes (bandwidth 4.48 GHz), its performance bandwidth is significantly improved, achieving near-full coverage broadband and efficient absorption in the Ku band (12-18 GHz), meeting the urgent needs of modern electronic devices for thin, broadband microwave absorption materials. Table 12 shows the effective absorption bandwidth and reflection loss ≤ -10 dB for different embodiments with a thickness of 1.5 mm. As can be seen from Table 12, the effective absorption bandwidth of the composite material increases with the addition of whisker-shaped carbon nanotubes; when the composition is sheet-like carbonyl iron: whisker-shaped carbon nanotubes = 50:2, the effective absorption bandwidth reaches its maximum value (covering 10.48 GHz to 17.68 GHz, with a bandwidth of 7.2 GHz). However, as the content of whisker carbon nanotubes increases further, their aggregation intensifies, leading to a decrease in microwave absorption performance. Therefore, adjusting the ratio of sheet-like carbonyl iron to whisker carbon nanotubes can effectively regulate the microwave absorption performance of the composite material.

[0064] Table 12. Effective absorption band and bandwidth for different embodiments with reflection loss values ​​≤ -10 dB at a thickness of 1.5 mm.

[0065]

[0066] Microscopic morphology: Figure 4The image shows a SEM image of whisker carbon nanotubes. As can be seen, compared with ordinary carbon nanotubes, whisker carbon nanotubes have a linear structure, do not entangle with each other, are easy to disperse, and are more likely to form a highly efficient conductive network in composite materials. Figure 5 This is a SEM cross-sectional image of Example 1. The sheet-like carbonyl iron and the whisker carbon nanotubes are uniformly dispersed in the PC / ABS matrix without obvious agglomeration. The whisker carbon nanotubes and the sheet-like carbonyl iron overlap each other to form a composite loss network with "magnetic-electric" synergy.

[0067] This embodiment successfully verified the technical effect of synergistically incorporating whisker carbon nanotubes and sheet-like carbonyl iron into a PC / ABS matrix. The three-dimensional conductive network of whisker carbon nanotubes introduces significant resistive losses and multipolarization mechanisms, which, combined with the magnetic losses provided by sheet-like carbonyl iron, jointly optimize the impedance matching and attenuation characteristics of the material. Thus, under the condition of limited physical thickness, a fundamental improvement in absorption performance is achieved from a single mechanism to multiple mechanisms, and from narrowband to broadband.

[0068] For any points not covered above, existing technologies shall apply.

[0069] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A microwave absorbing composite material, characterized in that, The following raw materials are mixed and melt-blended into shape: Polycarbonate / acrylonitrile-butadiene-styrene copolymer: 50 parts; Flake iron carbonyl: 10-50 parts; Whisker carbon nanotubes: 0.5-5 parts; Antioxidant: 0.5-3 parts; Flame retardant: 0.5-3 parts; Lubricant: 0.5-3 parts; The mass ratio of the whisker carbon nanotubes to the sheet-like carbonyl iron is (1.5~2.5):

50.

2. The microwave absorbing composite material according to claim 1, characterized in that, The polycarbonate / acrylonitrile-butadiene-styrene copolymer has a melt index of not less than 22 g / min under conditions of 220°C and 10 kg pressure.

3. The microwave absorbing composite material according to claim 1, characterized in that, The particle size of the plate-shaped carbonyl iron is 1-5 μm.

4. The microwave absorbing composite material according to claim 1, characterized in that, The whisker carbon nanotubes have an inner diameter of 2-5 nm, an outer diameter of 20-200 nm, and a length of 1-15 μm.

5. The microwave absorbing composite material according to any one of claims 1-4, characterized in that, The antioxidant is selected from one or more of tetrakis(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester.

6. The microwave absorbing composite material according to any one of claims 1-4, characterized in that, The flame retardant is zinc borate and / or bisphenol A bis(diphenyl phosphate).

7. The microwave absorbing composite material according to any one of claims 1-4, characterized in that, The lubricant is calcium stearate and / or zinc stearate.

8. The microwave absorbing composite material according to any one of claims 1-4, characterized in that, When the matching thickness is 1.5 mm, the absorbing composite material has an effective absorption frequency band of 10.48 GHz to 17.68 GHz with a reflection loss ≤ -10 dB, and an effective absorption bandwidth of 7.2 GHz.

9. A method for preparing a microwave absorbing composite material according to any one of claims 1-7, characterized in that, Includes the following steps: The polycarbonate / acrylonitrile-butadiene-styrene copolymer, sheet-like carbonyl iron, whisker carbon nanotubes, antioxidants, flame retardants and lubricants are placed in a high-speed mixer and mixed at a speed of 500~2000 r / min. The mixed materials are added to an internal mixer, melt-blended at a processing temperature of 220-240℃, cooled, and granulated to obtain the microwave absorbing composite material.

10. The application of the absorbing composite material as described in any one of claims 1-4 in electromagnetic interference suppression or band absorption of electronic devices, wherein the electronic devices include laptops, mobile phones, or routers.

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