High-strength and magnetoelectric synergistic electromagnetic shielding nanofiber composite membrane and its preparation method

Abstract

This application provides a high-strength and magnetoelectric synergistic electromagnetic shielding nanofiber composite membrane and its preparation method, belonging to the field of electromagnetic shielding materials. The preparation method uses PVA-co-PE nanofibers and ultra-high molecular weight polyethylene fibers as substrate materials, reduced graphene oxide as the dielectric loss medium, and magnetic iron oxide nanoparticles as the magnetic loss medium. A high-strength, tough, magnetoelectric synergistic PVA-co-PE / UHMWPE / RGO / Fe3O4 nanofiber composite membrane for efficient absorption and reflection of electromagnetic waves is prepared through high-speed shearing of PVA-co-PE nanofibers, vacuum-assisted filtration, and ultraviolet radiation crosslinking. On one hand, this application introduces crosslinking of UHMWPE and PVA-co-PE to construct an internally reinforced crosslinked structure, significantly improving the mechanical properties of the composite membrane. On the other hand, RGO interacts with magnetic Fe3O4 nanoparticles to form a layered alternating distribution structure of RGO and magnetic Fe3O4 nanoparticles. The resulting composite membrane exhibits excellent electromagnetic shielding performance in the ultra-wideband X-band, Ku-band, and K-band.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding materials technology, specifically to an electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy, and its preparation method. Background Technology

[0002] Electromagnetic interference shielding materials can effectively reduce electromagnetic radiation pollution to humans and electronic devices by absorbing or reflecting electromagnetic waves. In existing technologies, conductive polymer composites (CPCs) contain various conductive nanofillers. Due to their high specific surface area, these conductive nanofillers can create an interface between the polymer and nanomaterials that is conducive to electromagnetic wave polarization loss, thus significantly improving electromagnetic wave absorption efficiency. Materials such as metal nanowires, reduced graphene oxide (rGO), multi-walled carbon nanotubes (MWCNTs), and two-dimensional transition metal carbides / nitrides (2D MXenes) have been developed to supplement or replace traditional rigid and high-density metal shielding materials.

[0003] However, due to the high penetration threshold of CPCs, high filler content and large thickness are usually required to obtain ideal conductivity and EMI shielding performance, but this will lead to a decrease in the material's flexibility, mechanical properties (especially strength and toughness) and processability, thus reducing its practicality.

[0004] In view of this, it is necessary to design an electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy and its preparation method to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides an electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy and its preparation method. The preparation method uses PVA-co-PE nanofibers and ultra-high molecular weight polyethylene fibers (UHMWPE) as substrate raw materials, reduced graphene oxide (RGO) dispersion as dielectric loss medium, and magnetic iron oxide nanoparticle (Fe3O4) dispersion as magnetic loss medium. The PVA-co-PE / UHMWPE / RGO / Fe3O4 nanofiber composite membrane with high strength and toughness and magnetoelectric synergy for efficient absorption and reflection of electromagnetic waves is prepared by high-speed shearing of PVA-co-PE nanofibers, vacuum-assisted filtration, and ultraviolet radiation crosslinking.

[0006] In a first aspect, embodiments of this application provide a method for preparing an electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy, comprising the following steps:

[0007] S1, prepare a PVA-co-PE nanofiber suspension with a fiber content of 0.5wt% to 2wt%;

[0008] S2, the PVA-co-PE nanofiber suspension prepared in step S1 is mixed with reduced graphene oxide dispersion and magnetic iron oxide nanoparticle dispersion to form a PVA-co-PE / RGO / Fe3O4 mixed suspension; wherein, the mass ratio of each component in the PVA-co-PE / RGO / Fe3O4 mixed suspension is PVA-co-PE:RGO:Fe3O4 = 1.5:(0.05~0.07):(0.07~0.09);

[0009] S3, adding ultra-high molecular weight polyethylene fibers to the PVA-co-PE / RGO / Fe3O4 mixed suspension to obtain a multi-component mixed suspension; wherein, the mass of the ultra-high molecular weight polyethylene fibers is 2wt% to 7wt% of the mass of the PVA-co-PE nanofibers;

[0010] S4, the multi-component mixed suspension obtained in step S3 is placed in a vacuum-assisted filtration device, and a PVA-co-PE and UHMWPE nanofiber composite membrane is obtained by vacuum-assisted filtration.

[0011] S5, the PVA-co-PE and UHMWPE nanofiber composite membrane obtained in step S4 is immersed in a crosslinking agent, then placed under ultraviolet light for crosslinking, and naturally air-dried to obtain an electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy.

[0012] In the technical solution of this application embodiment, ultra-high molecular weight polyethylene fiber (UHMWPE) is introduced. PVA-co-PE nanofiber and UHMWPE are used as base materials. Reduced graphene oxide (RGO) dispersion is used as dielectric loss medium, and magnetic iron oxide nanoparticle (Fe3O4) dispersion is used as magnetic loss medium. UHMWPE and PVA-co-PE are crosslinked with the addition of a crosslinking agent and then crosslinked with ultraviolet radiation to construct an internally reinforced crosslinked structure, which greatly enhances the mechanical properties of the composite film and solves the problem of poor mechanical properties of conventional electromagnetic shielding film materials.

[0013] Furthermore, in step S3, in the multi-component mixed suspension, the mass percentage of the PVA-co-PE nanofibers is 0.5wt% to 2wt%, the mass percentage of the reduced graphene oxide is 0.05wt% to 0.07wt%, the mass percentage of the magnetic iron oxide nanoparticles is 0.07wt% to 0.09wt%, and the mass percentage of the ultra-high molecular weight polyethylene fiber is 0.01wt% to 0.14wt%.

[0014] Furthermore, in step S5, the mass percentage concentration of the crosslinking agent is 3%–5%, the crosslinking time under ultraviolet light is 20–40 min, and the crosslinking strength is 50 μW / cm. 2 .

[0015] Furthermore, the specific strength of the ultra-high molecular weight polyethylene fiber is 20–40 MPa·cm. 3 / g, specific modulus is 85~125GPa·cm 3 / g. The diameter of the ultra-high molecular weight polyethylene fiber is 10μm to 20μm, and the length is 30 to 50μm.

[0016] Furthermore, in step S1, the PVA-co-PE nanofiber suspension is prepared by dispersing isopropanol, deionized water and PVA-co-PE nanofibers in a certain proportion under a high-speed shearing machine at a volume ratio of 1:1.

[0017] Furthermore, the PVA-co-PE nanofibers have a diameter of 200 nm to 800 nm and a length of 20 to 50 μm.

[0018] Furthermore, in step S5, the crosslinking agent is obtained by diluting trimethylolpropane trimethacrylate with ethanol.

[0019] Secondly, embodiments of this application provide an electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy, which is prepared by the aforementioned technical solution. The nanofiber composite membrane has a porous network structure, and its electromagnetic shielding performance in the X-band is 35-37 dB, its electromagnetic shielding performance in the Ku-band is 33-36 dB, and its EMI SE value in the K-band is 35-38 dB.

[0020] The technical solution of this application embodiment uses reduced graphene oxide (RGO) dispersion as dielectric loss medium and magnetic iron oxide nanoparticle (Fe3O4) dispersion as magnetic loss medium. Through the multi-level synergistic effect of chemical cross-linking and multi-component interface enhancement (electrostatic interaction and weak chemical bonds between the interface of magnetic Fe3O4 nanoparticles and RGO, and chemical cross-linking between the interface of PVA-co-PE nanofibers and ultra-high molecular weight polyethylene fibers), a high-strength and high electromagnetic shielding performance nanofiber composite film is obtained.

[0021] Furthermore, in the nanofiber composite membrane, RGO has a sheet-like structure, and magnetic Fe3O4 nanoparticles are deposited on the surface of RGO. The two are distributed in an alternating layered structure within the nanofiber composite membrane.

[0022] Furthermore, the fracture stress of the nanofiber composite membrane is 10–12 MPa.

[0023] Reduced graphene oxide (RGO) interacts with magnetic magnetite nanoparticles through electrostatic interactions and weak chemical bonds. Numerous free electrons on the RGO surface interact with the electrons of the magnetite nanoparticles, forming an alternating structure of reduced graphene oxide (RGO) and magnetite nanoparticles (Fe3O4). Specifically, the RGO has a sheet-like structure, with magnetic Fe3O4 nanoparticles deposited on its surface, exhibiting a layered, alternating distribution within the nanofiber composite film. This significantly improves conductivity and electromagnetic interference shielding performance. The resulting nanofiber composite film demonstrates excellent electromagnetic shielding performance across an ultra-wideband X-band, Ku-band, and K-band, providing a new strategy for further expanding the application areas of electromagnetic shielding materials.

[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0026] Figure 1 This is a schematic flowchart illustrating the preparation method of the electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy according to the present invention.

[0027] Figure 2 This is a microscopic electron microscope image of a region of the electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy prepared in Example 1.

[0028] Figure 3 This is a micro-electron microscopy image of another region of the electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy prepared in Example 1.

[0029] Figure 4 The graph shows the electromagnetic shielding performance test results of the fiber membranes prepared in Example 1 and Comparative Example 1.

[0030] Figure 5 The graph shows the mechanical property test results of the fiber membranes prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0031] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0033] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0037] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0038] In a first aspect, embodiments of this application provide a method for preparing an electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy, comprising the following steps:

[0039] S1, prepare a PVA-co-PE nanofiber suspension with a fiber content of 0.5wt% to 2wt%;

[0040] S2, the PVA-co-PE nanofiber suspension prepared in step S1 is mixed with reduced graphene oxide dispersion and magnetic iron oxide nanoparticle dispersion to form a PVA-co-PE / RGO / Fe3O4 mixed suspension; wherein, the mass ratio of each component in the PVA-co-PE / RGO / Fe3O4 mixed suspension is PVA-co-PE:RGO:Fe3O4 = 1.5:(0.05~0.07):(0.07~0.09);

[0041] S3, adding ultra-high molecular weight polyethylene fibers to the PVA-co-PE / RGO / Fe3O4 mixed suspension to obtain a multi-component mixed suspension; wherein, the mass of the ultra-high molecular weight polyethylene fibers is 2wt% to 7wt% of the mass of the PVA-co-PE nanofibers;

[0042] S4, the multi-component mixed suspension obtained in step S3 is placed in a vacuum-assisted filtration device, and a PVA-co-PE and UHMWPE nanofiber composite membrane is obtained by vacuum-assisted filtration.

[0043] S5, the PVA-co-PE and UHMWPE nanofiber composite membrane obtained in step S4 is immersed in a crosslinking agent, then placed under ultraviolet light for crosslinking, and naturally air-dried to obtain an electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy.

[0044] This application introduces ultra-high molecular weight polyethylene fiber (UHMWPE), using PVA-co-PE nanofibers and UHMWPE as base materials, reduced graphene oxide (RGO) dispersion as dielectric loss medium, and magnetic iron oxide nanoparticle (Fe3O4) dispersion as magnetic loss medium. A high-strength and tough magnetoelectric synergistic PVA-co-PE / UHMWPE / RGO / Fe3O4 nanofiber composite membrane for efficient absorption and reflection of electromagnetic waves is prepared by high-speed shearing of PVA-co-PE nanofibers, vacuum-assisted filtration, and ultraviolet radiation crosslinking.

[0045] Electromagnetic interference shielding materials attenuate incident electromagnetic waves through a combination of electrical, magnetic, and dielectric losses. Introducing magnetic particles into conductive polymer composites can promote absorption caused by magnetic losses, thereby mitigating the harmful effects of secondary electromagnetic wave reflections. Magnetic iron oxide nanoparticles (Fe3O4), due to their strong magnetic properties, can effectively attenuate incident electromagnetic waves through magnetic losses.

[0046] The high conductivity of reduced graphene oxide (RGO) helps to form an effective conductive path, which can create an interface between polymers and nanomaterials that is conducive to electromagnetic wave polarization loss, making the composite material show good prospects in terms of electromagnetic interference shielding.

[0047] Reduced graphene oxide (RGO) interacts with magnetic magnetite nanoparticles through electrostatic interactions and weak chemical bonds. Numerous free electrons on the RGO surface interact with the electrons of the magnetite nanoparticles, forming an alternating distribution structure of reduced graphene oxide (RGO) and magnetite nanoparticles (Fe3O4). Specifically, the RGO has a sheet-like structure, with magnetic Fe3O4 nanoparticles deposited on its surface, exhibiting a layered, alternating distribution within the nanofiber composite film. This significantly improves electrical conductivity and electromagnetic interference shielding performance. The fabricated nanofiber composite film demonstrates excellent electromagnetic shielding performance across an ultra-wideband X-band, Ku-band, and K-band, providing a new strategy for further expanding the application areas of electromagnetic shielding materials.

[0048] The PVA-co-PE / UHMWPE / RGO / Fe3O4 nanofiber membrane prepared in this application has a porous network structure, high absorption performance and high strength and toughness. These excellent comprehensive properties have great potential for the application of electromagnetic shielding materials.

[0049] In step S1, the PVA-co-PE nanofiber suspension is prepared by dispersing isopropanol, deionized water and PVA-co-PE nanofibers in a certain proportion under a high-speed shearing machine at a volume ratio of 1:1.

[0050] The diameter of PVA-co-PE nanofibers ranges from 200 nm to 800 nm, and the length ranges from 20 to 50 μm.

[0051] Ultra-high molecular weight polyethylene (UHMWPE) fibers possess high specific strength and high specific modulus. Specifically, the specific strength of UHMWPE fibers is 20–40 MPa·cm. 3 / g, specific modulus is 85~125GPa·cm 3 / g. The diameter of ultra-high molecular weight polyethylene fiber is 10μm to 20μm, and the length is 30 to 50μm.

[0052] In step S5, the mass percentage concentration of the crosslinking agent is 3%–5%, the crosslinking time under ultraviolet light is 20–40 min, and the crosslinking strength is 50 μW / cm. 2 .

[0053] This application introduces ultra-high molecular weight polyethylene fiber (UHMWPE). UHMWPE and PVA-co-PE are crosslinked with a crosslinking agent and then crosslinked with ultraviolet radiation to construct an internal composite reinforced crosslinking structure, which enhances the mechanical properties of the composite film and solves the problem of poor mechanical properties of conventional electromagnetic shielding film materials.

[0054] Specifically, in step S3, the mass percentage of PVA-co-PE nanofibers in the multi-component mixed suspension is 0.5wt% to 2wt%.

[0055] The mass percentage of reduced graphene oxide is 0.05wt% to 0.07wt%, the mass percentage of magnetic iron oxide nanoparticles is 0.07wt% to 0.09wt%, and the mass percentage of ultra-high molecular weight polyethylene fiber is 0.01wt% to 0.14wt%.

[0056] In step S5, the crosslinking agent is obtained by diluting trimethylolpropane trimethacrylate with ethanol.

[0057] Secondly, embodiments of this application provide an electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy, which is prepared by the aforementioned preparation method. The prepared nanofiber composite membrane has a porous network structure, with electromagnetic shielding performance of 35-37 dB in the X-band, electromagnetic shielding performance of 33-36 dB in the Ku-band, and EMI SE value of 35-38 dB in the K-band.

[0058] In the nanofiber composite membrane, RGO has a sheet-like structure, and magnetic Fe3O4 nanoparticles are deposited on the RGO surface. The two are distributed in an alternating layered structure within the nanofiber composite membrane.

[0059] The nanofiber composite membrane exhibits a fracture stress of 10–12 MPa, demonstrating excellent mechanical properties.

[0060] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with 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 conventional products that can be obtained commercially.

[0061] Example 1

[0062] Please see Figure 1 As shown, this embodiment provides a method for preparing an electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy, including the following steps:

[0063] S1, Prepare a PVA-co-PE nanofiber suspension with a fiber content of 2wt%;

[0064] S2, the PVA-co-PE nanofiber suspension prepared in step S1 is mixed with reduced graphene oxide dispersion and magnetic iron oxide nanoparticle dispersion to form a PVA-co-PE / RGO / Fe3O4 mixed suspension; wherein, the mass ratio of each component in the PVA-co-PE / RGO / Fe3O4 mixed suspension is PVA-co-PE:RGO:Fe3O4=1.5:0.06:0.08;

[0065] S3, ultra-high molecular weight polyethylene fibers are added to a PVA-co-PE / RGO / Fe3O4 mixed suspension to obtain a multi-component mixed suspension; wherein, the mass of ultra-high molecular weight polyethylene fibers is 5 wt% of the mass of PVA-co-PE nanofibers;

[0066] S4. The multi-component mixed suspension obtained in step S3 is placed in a vacuum-assisted filtration device with a vacuum degree of -0.1MPa. A PVA-co-PE and UHMWPE nanofiber composite membrane is obtained by vacuum-assisted filtration.

[0067] S5, the PVA-co-PE and UHMWPE nanofiber composite membrane obtained in step S4 is immersed in TMPTMA crosslinking agent (mass percentage concentration of 5%), and then subjected to crosslinking under ultraviolet light with an ultraviolet intensity of 50 μW / cm. 2 The processing time was 30 minutes. After the crosslinking was completed, the PVA-co-PE and UHMWPE nanofiber composite membrane was taken out and air-dried naturally to obtain a high-strength and tough PVA-co-PE / UHMWPE / RGO / Fe3O4 nanofiber composite membrane with high magnetic-electric synergistic effect.

[0068] Please see Figures 2 to 3 The image shown is an electron microscope image of the electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy prepared in Example 1. As can be seen from the image, the RGO has a sheet-like structure, with magnetic Fe3O4 nanoparticles deposited on the RGO surface, exhibiting an alternating layered distribution throughout the nanofiber composite film.

[0069] Comparative Example 1

[0070] Comparative Example 1 provides a method for preparing a nanofiber membrane. Compared with Example 1, the difference is that steps S3 and S5 are not performed. That is, only the PVA-co-PE nanofiber suspension from step S1 is used to obtain a nanofiber composite membrane (PVA-co-PE / RGO / Fe3O4) by vacuum-assisted filtration.

[0071] Please see Figures 4 to 5 The figure shown is a graph of the electromagnetic shielding performance and mechanical performance test results of the fiber membranes prepared in Example 1 and Comparative Example 1.

[0072] from Figure 4 It can be seen that the nanofiber composite membrane (PVA-co-PE / UHMWPE / RGO / Fe3O4) prepared in Example 1 has significantly improved electromagnetic shielding performance in the X-band and Ku-band compared with the unmodified PVA-co-PE nanofiber membrane in Comparative Example 1. Specifically, in the X-band, its electromagnetic shielding performance increased from 3dB to 37dB, an improvement of more than 12 times. Figure 4 As shown in (a) above. In the Ku band, its electromagnetic shielding was improved from 2dB to 33dB, a performance improvement of more than 16 times, as... Figure 4 As shown in (b) of the diagram.

[0073] The EMI SE value in the K-band increased from 3dB to 36dB, nearly 12 times higher than before. Figure 4 As shown in (c) in the figure.

[0074] from Figure 5 As can be seen, compared with the unmodified nanofiber composite membrane (PVA-co-PE / RGO / Fe3O4) in Comparative Example 1, the nanofiber composite membrane prepared in Example 1 (PVA-co-PE / RGO / Fe3O4) showed an increase in fracture stress from 5 MPa to 11 MPa, which is 140% higher, and a 100% increase in fracture strain, demonstrating good mechanical properties.

[0075] Comparative Example 2

[0076] Comparative Example 2 provides a method for preparing a nanofiber membrane. The difference from Example 1 is that in step S2, reduced graphene oxide was not added to obtain a nanofiber composite membrane (PVA-co-PE / UHMWPE / Fe3O4). The rest is roughly the same as in Example 1, and will not be repeated here.

[0077] Comparative Example 3

[0078] Comparative Example 3 provides a method for preparing a nanofiber membrane. Compared with Example 1, the difference is that Fe3O4 was not added in step S2, and a nanofiber composite membrane (PVA-co-PE / UHMWPE / RGO) was obtained. The rest is roughly the same as Example 1, and will not be repeated here.

[0079] Comparative Example 4

[0080] Comparative Example 4 provides a method for preparing a nanofiber membrane. Compared with Example 1, the difference is that in step S2, reduced graphene oxide is replaced with carbon nanotubes to obtain a nanofiber composite membrane (PVA-co-PE / MW-CNTs / Fe3O4). The rest is roughly the same as in Example 1 and will not be described again here.

[0081] Comparative Example 5

[0082] Comparative Example 5 provides a method for preparing a nanofiber membrane. Compared with Example 1, the difference is that step S1 is not performed, and the multi-component mixed suspension does not contain PVA-co-PE nanofibers. The rest is roughly the same as Example 1, and will not be described again here.

[0083] The electromagnetic shielding performance and mechanical properties of the nanofiber composite membranes prepared in Example 1 and Comparative Examples 1-5 were tested, and the results are shown in the table below.

[0084] Electromagnetic shielding (dB) Mechanical properties (MPa) Example 1 36 11 Comparative Example 1 36 5 Comparative Example 2 10 9 Comparative Example 3 19 10 Comparative Example 4 30 9 Comparative Example 5 / /

[0085] Experiments have shown that when PVA-co-PE nanofibers and ultra-high molecular weight polyethylene fibers (UHMWPE) are cross-linked by ultraviolet radiation, their electromagnetic shielding performance and mechanical properties are greatly improved.

[0086] In Example 1, ultra-high molecular weight polyethylene (UHMWPE) fibers are integrated throughout the entire composite membrane structure, acting as a bridge and support. In Comparative Example 1, the absence of UHMWPE fibers resulted in a decrease in mechanical properties. In Comparative Example 2, the absence of RGO (reduced free radical) deprived the composite membrane of dielectric loss, leading to a decrease in electromagnetic shielding performance. In Comparative Example 3, the absence of Fe3O4 deprived the composite membrane of magnetic loss, resulting in a decrease in electromagnetic shielding performance.

[0087] Comparative Example 4 showed that replacing reduced graphene oxide with carbon nanotubes did not perform well in terms of electromagnetic shielding and mechanical properties. This may be because carbon nanotubes cannot interact with magnetic Fe3O4 nanoparticles through electrostatic interactions and weak chemical bonds, and there are no free electrons on the surface of carbon nanotubes to interact with the electrons of magnetic Fe3O4 nanoparticles, which reduces the electromagnetic interference shielding performance of the nanofiber composite film.

[0088] In Comparative Example 5, the experiment found that without PVA-co-PE nanofibers, the main substrate is missing, and nanofiber membranes cannot be formed.

[0089] Examples 2-3 and Comparative Examples 6-7

[0090] Examples 2-3 and Comparative Examples 6-7 provide a method for preparing an electromagnetically shielding nanofiber composite film with high strength and magnetoelectric synergy. Compared with Example 1, the difference lies in the change of the mass ratio of ultra-high molecular weight polyethylene fibers in step S3, as shown in the table below. The rest is roughly the same as in Example 1 and will not be repeated here.

[0091]

[0092] Experiments show that when the mass percentage of UHMWPE in the PVA-co-PE nanofibers exceeds 7wt%, the penetration ratio of UHMWPE in the nanofiber composite membrane will be too high, and the toughness of the nanofiber composite membrane will decrease significantly.

[0093] When the percentage of UHMWPE mass in the PVA-co-PE nanofiber mass is less than 2wt%, the penetration ratio of UHMWPE in the nanofiber composite membrane will decrease, and the strength of the nanofiber composite membrane will decrease significantly.

[0094] Examples 4-6 and Comparative Examples 8-9

[0095] Examples 4-6 and Comparative Examples 8-9 provide a method for preparing an electromagnetically shielding nanofiber composite membrane with high strength and magnetoelectric synergy. The difference from Example 1 lies in the change of the mass ratio of each component in the PVA-co-PE / RGO / Fe3O4 mixed suspension in step S2, as shown in the table below. The rest is largely the same as in Example 1 and will not be repeated here.

[0096]

[0097] As shown in the table above, when the mass ratio of each component in the PVA-co-PE / RGO / Fe3O4 mixed suspension exceeds the range of 1.5:(0.05~0.07):(0.07~0.09), the electrostatic interaction and weak chemical bond force between RGO and magnetic Fe3O4 nanoparticles will be relatively weakened, and the electronic interaction between free electrons on RGO and magnetic Fe3O4 nanoparticles will also be relatively reduced, thus weakening the electromagnetic interference shielding performance.

[0098] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing an electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy, characterized in that, Includes the following steps: S1, prepare a PVA-co-PE nanofiber suspension with a fiber content of 0.5wt% to 2wt%; S2, the PVA-co-PE nanofiber suspension prepared in step S1 is mixed with reduced graphene oxide dispersion and magnetic iron oxide nanoparticle dispersion to form a PVA-co-PE / RGO / Fe3O4 mixed suspension; wherein, the mass ratio of each component in the PVA-co-PE / RGO / Fe3O4 mixed suspension is PVA-co-PE:RGO:Fe3O4 = 1.5:(0.05~0.07):(0.07~0.09); S3, adding ultra-high molecular weight polyethylene fibers to the PVA-co-PE / RGO / Fe3O4 mixed suspension to obtain a multi-component mixed suspension; wherein, the mass of the ultra-high molecular weight polyethylene fibers is 2wt% to 7wt% of the mass of the PVA-co-PE nanofibers; S4, the multi-component mixed suspension obtained in step S3 is placed in a vacuum-assisted filtration device, and a PVA-co-PE and UHMWPE nanofiber composite membrane is obtained by vacuum-assisted filtration. S5, the PVA-co-PE and UHMWPE nanofiber composite membrane obtained in step S4 is immersed in a crosslinking agent, then placed under ultraviolet light for crosslinking, and naturally air-dried to obtain an electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy.

2. The method for preparing the electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy according to claim 1, characterized in that, In step S3, the multi-component mixed suspension contains PVA-co-PE nanofibers at a mass percentage of 0.5 wt% to 2 wt%, reduced graphene oxide at a mass percentage of 0.05 wt% to 0.07 wt%, magnetic iron oxide nanoparticles at a mass percentage of 0.07 wt% to 0.09 wt%, and ultra-high molecular weight polyethylene fibers at a mass percentage of 0.01 wt% to 0.14 wt%.

3. The method for preparing the electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy according to claim 1, characterized in that, In step S5, the mass percentage concentration of the crosslinking agent is 3%–5%, the crosslinking time under ultraviolet light is 20–40 min, and the crosslinking strength is 50 μW / cm. 2 .

4. The method for preparing the electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy according to claim 1, characterized in that, The specific strength of the ultra-high molecular weight polyethylene fiber is 20–40 MPa·cm. 3 / g, specific modulus is 85~125GPa·cm 3 / g; the diameter of the ultra-high molecular weight polyethylene fiber is 10μm to 20μm and the length is 30 to 50μm.

5. The method for preparing the electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy according to claim 1, characterized in that, In step S1, the PVA-co-PE nanofiber suspension is prepared by dispersing isopropanol, deionized water and PVA-co-PE nanofibers in a high-speed shearing machine at a volume ratio of 1:

1.

6. The method for preparing the electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy according to claim 1, characterized in that, The PVA-co-PE nanofibers have a diameter of 200 nm to 800 nm and a length of 20 to 50 μm.

7. The method for preparing the electromagnetic shielding nanofiber composite film with high strength and magnetoelectric synergy according to claim 1, characterized in that, In step S5, the crosslinking agent is obtained by diluting trimethylolpropane trimethacrylate with ethanol.

8. A high-strength, magnetoelectric synergistic electromagnetic shielding nanofiber composite membrane, characterized in that, The nanofiber composite membrane prepared by any one of claims 1-7 has a porous network structure, and its electromagnetic shielding performance in the X-band is 35-37 dB, its electromagnetic shielding performance in the Ku-band is 33-36 dB, and its EMI SE value in the K-band is 35-38 dB.

9. The electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy according to claim 8, characterized in that, In the nanofiber composite membrane, RGO has a sheet-like structure, and magnetic Fe3O4 nanoparticles are deposited on the surface of RGO. The two are distributed in an alternating layered structure within the nanofiber composite membrane.

10. The electromagnetic shielding nanofiber composite membrane with high strength and magnetoelectric synergy according to claim 8, characterized in that, The fracture stress of the nanofiber composite membrane is 10–12 MPa.

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