Laser-induced graphene smart honeycomb structure material and preparation method thereof, smart sandwich honeycomb structure material and application

Abstract

The application provides a laser-induced graphene smart honeycomb structure material and a preparation method, a smart sandwich honeycomb structure material and application, and belongs to the technical field of smart honeycomb structure materials.The application comprises the following steps: laser-induced double-sided polyimide substrates are obtained, the laser-induced double-sided polyimide substrates comprise a first graphene layer, a polyimide layer and a second graphene layer which are arranged in a stack; at least two layers of the laser-induced graphene substrates and a plurality of thermoplastic core strip glues are assembled, and then sequentially subjected to hot pressing, stretching, glue dipping and curing to obtain the laser-induced graphene smart honeycomb structure material; and a plurality of the thermoplastic core strip glues are arranged in parallel between the two adjacent layers of the laser-induced graphene substrates.The application combines laser-induced technology and honeycomb manufacturing technology to realize in-situ integrated manufacturing of the laser-induced graphene smart honeycomb structure material, and has the advantages of simple operation, low cost, high efficiency and mild preparation conditions, and is convenient for realizing the regulation of structure, size and function.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of intelligent cellular structure materials, in particular to a laser-induced graphene intelligent cellular structure material, a preparation method thereof, an intelligent sandwich cellular structure material and application. BACKGROUND

[0002] The cellular structure material has extraordinary mechanical advantages, including low density, high specific strength and stiffness, excellent energy absorption and bearing capacity, due to its unique hexagonal biomimetic cellular structure, which ensures its multi-scene application in aerospace, civil engineering, transportation industry, etc. The patent with the application number CN202110599041.7 discloses a method for preparing aramid honeycomb, which needs to perform intaglio printing of core strip glue at specific positions of the paper material. The core strip glue used is liquid (such as the core strip glue disclosed in the patent with the application number CN201810245105.1), which will rapidly spread and penetrate in the paper-based material rich in porous structure, causing bonding at non-specified positions and affecting the formation of the cellular structure. In addition to the structural and mechanical advantages, the traditional cellular structure may still be threatened by harsh working conditions such as high temperature, high-speed impact, ice accumulation and electromagnetic pollution if it does not have real-time sensing and response capabilities.

[0003] The intelligent honeycomb structure material with multifunctional properties such as intelligent sensing, high-temperature warning, flame retardation, chemical corrosion resistance, and electromagnetic wave shielding and absorption has attracted extensive attention of researchers by subverting the traditional structure. Paper-based honeycomb has the structural advantage of lightweight weight reduction compared with metal-based honeycomb, and plays an important role in the fields of aerospace, vehicle transportation, etc., so it is necessary to develop an intelligent paper-based honeycomb structure material. In the prior art, it is reported that the multifunctional insulation honeycomb is obtained by impregnating treatment or patching treatment on the formed aramid honeycomb structure, wherein the impregnating treatment (such as document Luo H, Chen F, Wang X, Dai W, Xiong Y, Yang J, et al. (2019). A novel two-layer honeycomb sandwich structure absorber with high-performance microwave absorption. Composites Part A Applied Science & Manufacturing.) is to immerse the aramid honeycomb in a carbon or graphene conductive slurry, and after the slurry is solidified and formed, the insulation aramid honeycomb has the function of electromagnetic shielding; the patching treatment (such as patent CA2896645: SYSTEMS AND METHODS FOR CONTROL OF A NON-DESTRUCTIVE TESTING SYSTEM) is to attach an antenna sheet on the surface of the aramid honeycomb, which can transmit electromagnetic signals, so that the honeycomb structure material has efficient radiation and impedance characteristics and can be used for satellite communication. As can be seen, the construction of the traditional intelligent honeycomb structure cannot realize integrated manufacturing, and additional processes are inevitably needed to realize the intelligentization of the honeycomb structure. SUMMARY

[0004] The present application aims to provide a laser-induced graphene intelligent honeycomb structure material and its preparation method, an intelligent sandwich honeycomb structure material and its application. The method provided by the present application can realize in-situ integrated manufacturing of the intelligent honeycomb structure material, and has the advantages of simple operation, low cost, high efficiency and mild preparation conditions.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a preparation method of a laser-induced graphene intelligent honeycomb structure material, comprising the following steps:

[0007] The laser-induced double-sided polyimide substrate is obtained, and the laser-induced graphene substrate comprises a first graphene layer, a polyimide layer and a second graphene layer which are arranged in layers;

[0008] The at least two layers of the laser-induced graphene base and a plurality of thermoplastic core strip glues are sequentially subjected to hot pressing, stretching, impregnation and curing after being assembled to obtain the laser-induced graphene intelligent honeycomb structure material; and a plurality of the thermoplastic core strip glues are arranged in parallel between the adjacent two layers of the laser-induced graphene base.

[0009] Preferably, when the number of layers of the laser-induced graphene base in the laser-induced graphene intelligent honeycomb structure material is greater than or equal to 3, the projection area of the thermoplastic core strip glue on the upper surface and the lower surface of the laser-induced graphene base in the non-surface position in the laser-induced graphene intelligent honeycomb structure material does not overlap.

[0010] Preferably, the thermoplastic core strip glue is obtained by cutting a thermoplastic film, and the thermoplastic film comprises one or more of thermoplastic polyurethane film, polyethylene film, polypropylene film, polyvinyl chloride film, polystyrene film, polyester film and polyphthalamide film; the thickness of the thermoplastic film is 10-100 μm.

[0011] Preferably, the polyimide base comprises one or more of polyimide paper, polyimide felt, polyimide film and polyimide cloth; the thickness of each layer of the polyimide base is 10-200 μm.

[0012] Preferably, the laser-induced conditions comprise: laser power ≤ 25 W, laser running speed ≤ 1270 mm / s, pixels per inch ≤ 1000, and defocusing distance ≤ 4 mm; and the thickness of the polyimide layer in each layer of the laser-induced graphene base is independently 20-90 μm.

[0013] Preferably, the hot pressing conditions comprise: temperature 80-200 ℃, pressure 1-10 MPa, and holding time 1-1000 min.

[0014] Preferably, the resin material used for impregnation is a thermosetting resin, and the thermosetting resin comprises one or more of epoxy resin, polyester resin, phenolic resin, melamine formaldehyde resin, furan resin, polybutadiene resin and silicone resin.

[0015] The application provides a laser-induced graphene intelligent honeycomb structure material prepared by the preparation method.

[0016] The application provides an intelligent sandwich honeycomb structure material, which comprises the laser-induced graphene intelligent honeycomb structure material and a skin arranged on the upper surface and the lower surface of the laser-induced graphene intelligent honeycomb structure material.

[0017] The application provides application of the laser-induced graphene intelligent honeycomb structure material or the intelligent sandwich honeycomb structure material in electric heating, ice prevention, ice removal, high-temperature early warning, fire retardation, pressure sensing, vibration monitoring, electromagnetic shielding and stealth fields.

[0018] The application provides a preparation method of a laser-induced graphene intelligent honeycomb structure material, which comprises the following steps: laser-induced double-sided polyimide substrate to obtain a laser-induced graphene substrate; the laser-induced graphene substrate comprises a first graphene layer, a polyimide layer and a second graphene layer which are arranged in a stack; at least two layers of the laser-induced graphene substrate and a plurality of thermoplastic core strip glues are assembled and then sequentially subjected to hot pressing, stretching, glue dipping and curing to obtain the laser-induced graphene intelligent honeycomb structure material; and a plurality of the thermoplastic core strip glues are arranged in parallel between the two adjacent layers of the laser-induced graphene substrate. The application realizes in-situ integrated manufacturing of the laser-induced graphene intelligent honeycomb structure material (3D LIG-HC) by combining laser-induced technology and honeycomb manufacturing technology, and has the advantages of simple operation, low cost, high efficiency and mild preparation conditions. The method provided by the application facilitates the regulation of the structure and size of the 3D LIG-HC, and thus the regulation of the functions of the 3D LIG-HC, including anisotropic mechanical, electrical, piezoresistive and electromagnetic properties. The results in the embodiments show that the 3D LIG-HC provided by the application can be applied in the fields of electric heating, ice prevention, ice removal, high-temperature early warning, fire retardation, pressure sensing, vibration monitoring, electromagnetic shielding and stealth. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 LIGP cross-sectional schematic diagram and cross-sectional scanning electron microscope diagram;

[0020] Figure 2 PI paper and LIGP surface scanning electron microscope diagram, transmission electron microscope diagram, Raman spectrum diagram, XRD diagram and EDS diagram;

[0021] Figure 3 LIGP surface scanning electron microscope diagrams prepared under different laser power and defocusing distance conditions;

[0022] Figure 4 Raman spectrum diagrams of LIGPs prepared under different laser power conditions;

[0023] Figure 5 Cross-sectional scanning electron microscope diagrams of LIGPs prepared under different laser power conditions;

[0024] Figure 6 Quantitative relationship diagram of LIG layer thickness and residual PI layer thickness of LIGPs prepared under different laser power conditions;

[0025] Figure 7 Graphs of resistance test and mechanical property test results for LIGP prepared under different laser power conditions;

[0026] Figure 8 Graphs of thermal performance analysis for TPU film;

[0027] Figure 9 Graphs of preparation process for 3D LIG-HC;

[0028] Figure 10 Graphs of structure pre-design for 3D LIG-HC;

[0029] Figure 11 Graphs of structure pre-design for 3D LIG / PI-HC with multi-unit graphene cluster structure;

[0030] Figure 12 Graphs of diversified 3D LIG-HC structure display;

[0031] Figure 13 Graphs of Sandwich HC structure display with different skin structures;

[0032] Figure 14 Graphs of 3D LIG-HC large deformation tolerance, lightweight, and load-bearing characteristics test;

[0033] Figure 15 Graphs of 3D LIG-HC formability study;

[0034] Figure 16 Graphs of 3D LIG-HC multifunctional performance test results;

[0035] Figure 17 Graphs of 3D LIG-HC test results for ice prevention and removal applications;

[0036] Figure 18 Graphs of 3D LIG-HC test results for high-temperature early warning monitoring applications;

[0037] Figure 19 Graphs of 3D LIG-HC test results for flame retardant applications;

[0038] Figure 20 Graphs of 3D LIG-HC test results for array sensing applications;

[0039] Figure 21 Graphs of 3D LIG-HC test results for two-unit stress detection applications;

[0040] Figure 22 Graphs of 3D LIG-HC test results for frequency detection applications;

[0041] Figure 23 Figure 3 shows the test results of 3D LIG-HC for electromagnetic shielding and stealth. DETAILED DESCRIPTION

[0042] The application provides a preparation method of a laser-induced graphene smart honeycomb structure material, and comprises the following steps:

[0043] The laser-induced graphene substrate is obtained by laser-induced double-sided polyimide substrate; the laser-induced graphene substrate comprises a first graphene layer, a polyimide layer and a second graphene layer which are arranged in a stack.

[0044] The laser-induced graphene smart honeycomb structure material is obtained by sequentially performing hot pressing, stretching, impregnation and curing on the at least two layers of laser-induced graphene substrates and the plurality of thermoplastic core strip glues; and a plurality of thermoplastic core strip glues are arranged in parallel between the adjacent two layers of laser-induced graphene substrates.

[0045] In the application, unless otherwise specified, the materials used are commercially available or prepared by methods known to those skilled in the art.

[0046] The application discloses a laser-induced double-sided polyimide (PI) substrate, and obtains a laser-induced graphene substrate. In the application, the polyimide substrate preferably comprises one or more of polyimide paper, polyimide felt, polyimide film and polyimide cloth, and more preferably is polyimide paper; the thickness of each layer of the polyimide substrate is preferably 10-200 μm, more preferably 50-150 μm, and further preferably 90 μm. In the application, the polyimide paper is preferably a polyimide precursor polyamic acid (PAA) solution spun fiber felt, and the PAA is subjected to an amidation reaction to obtain a polyimide fiber felt, i.e. polyimide paper (PI paper); in the embodiment of the application, the polyimide paper is specifically purchased from Changchun Gaoci Polyimide Material Co., Ltd., and has a thickness of 90 μm. In the application, the laser-induced conditions comprise: the laser power is preferably ≤25 W, more preferably 1-20 W, and further preferably 7.5-15 W, and specifically can be 7.5 W, 8 W, 8.5 W, 9 W, 9.5 W, 10 W, 10.5 W, 11 W, 11.5 W, 12 W, 12.5 W, 13 W, 13.5 W, 14 W, 14.5 W or 15 W; the laser running speed is preferably ≤1270 mm / s, and more preferably 635 mm / s; the pixels per inch (PPI) is preferably ≤1000, and more preferably 500; and the defocus distance (DL) is preferably ≤4 mm, and more preferably 3 mm. In the application, the laser used in the laser induction preferably comprises an ultraviolet laser, a femtosecond laser, a 1.06 μm fiber laser, a 9.3 μm carbon dioxide infrared laser or a 10.6 μm carbon dioxide infrared laser, and more preferably is a 10.6 μm carbon dioxide infrared laser; the rated power of the 10.6 μm carbon dioxide infrared laser preferably comprises 10-150 W, and more preferably is 25 W. In the application, the mode of the laser induction preferably comprises a vector mode or a fill mode, and more preferably is a fill mode; the full load speed of the vector mode is preferably 254 mm / s, and the full load speed of the fill mode is preferably 1270 mm / s. In the application, in the process of laser induction of the double-sided polyimide substrate, the same or different laser parameters can be selected to induce the double sides of the polyimide substrate, and the same laser parameters are preferentially selected to induce the double sides of the polyimide paper. In the application, the laser-induced graphene substrate comprises a first graphene layer, a polyimide layer and a second graphene layer arranged in a stack, and the thickness of each layer of the polyimide layer in the laser-induced graphene substrate is independently preferably 20-90 μm, more preferably 27-76 μm, and further preferably 32.5 μm. That is, the application controls the conditions of laser induction to ensure that only the upper surface and the lower surface of the polyimide substrate are partially graphitized, and the middle part still retains polyimide, so that the laser-induced graphene substrate has a relatively high tensile strength, and the honeycomb structure formed in the subsequent stretching process is avoided from being damaged.

[0047] After obtaining the laser-induced graphene substrate, the present application assembles at least two layers of the laser-induced graphene substrate and a plurality of thermoplastic core strip glues to obtain an assembly. The present application preferably selects the number of layers of the laser-induced graphene substrate in the laser-induced graphene smart honeycomb structure material according to actual needs, and the number of layers of the laser-induced graphene substrate in the laser-induced graphene smart honeycomb structure material is preferably 2-1000 layers, more preferably 5-500 layers, more preferably 10-100 layers, and more preferably 20-50 layers. In the present application, the thermoplastic core strip glue is preferably obtained by cutting a thermoplastic film, and the thermoplastic film preferably includes one or more of thermoplastic polyurethane (TPU) film, polyethylene film, polypropylene film, polyvinyl chloride film, polystyrene film, polyester film and polyphthalamide film, and more preferably TPU film; the thickness of the thermoplastic film is preferably 10-100 μm, more preferably 30-70 μm, and further preferably 50 μm; in the embodiments of the present application, the TPU film is purchased from Dongguan Xinrui Plastic Products Co., Ltd., and the thickness is 50 μm. In the present application, the assembly is obtained by arranging a plurality of thermoplastic core strip glues in parallel between adjacent two layers of the laser-induced graphene substrate, that is, the number of layers of the thermoplastic core strip glue is equal to the total number of layers of the laser-induced graphene substrate minus 1. The thermoplastic core strip glue in the present application plays a role in bonding adjacent laser-induced graphene substrates, ensuring that the final target material with a honeycomb structure, i.e., a laser-induced graphene smart honeycomb structure material, is obtained. In the present application, when the number of layers of the laser-induced graphene substrate in the laser-induced graphene smart honeycomb structure material is ≥3 layers, the projection area of the thermoplastic core strip glue on the upper surface and the lower surface of the laser-induced graphene substrate in the non-surface position in the laser-induced graphene smart honeycomb structure material preferably does not overlap. The present application preferably uses CAD software or CorelDRAW software to design the shape and size of the laser-induced graphene substrate and the thermoplastic core strip glue, and then cuts them into the preset shape and size; the cutting is preferably laser cutting, and the conditions of the laser cutting include: the laser power is preferably 1-25 W, and more preferably 2 W; the laser running speed is preferably 2.54-50.8 mm / s, and more preferably 12.7 mm / s; the PPI is preferably 1-1000, and more preferably 500; and the defocusing distance is preferably ≤4 mm, and more preferably 0 mm (i.e., cutting under focusing). In the present application, the shape and size of the cell (i.e., the honeycomb unit) in the target material are related to the shape and size of the laser-induced graphene substrate and the thermoplastic core strip glue. Specifically, the side length of the honeycomb unit can be determined by designing the structure of the thermoplastic core strip glue; the shape of the honeycomb unit can be determined by controlling the degree of stretching after hot pressing; the number of honeycomb units can be determined by adjusting the length and number of layers of the laser-induced graphene substrate; and the three-dimensional size of the whole target material can be determined by the side length, shape, length and number of layers of the laser-induced graphene substrate.

[0048] In the embodiments of the present application, the thermoplastic film is taken as an example of TPU film, specifically, the TPU film is cut to obtain two structures of cut TPU, which are defined as TPU-1 and TPU-2 respectively; both the TPU-1 and the TPU-2 are in the shape of a ladder, including two TPU connecting arms in parallel distribution and a plurality of TPU strips (i.e. corresponding to the thermoplastic core strip adhesive) in parallel distribution, one end of each of the TPU strips is perpendicularly connected to one of the TPU connecting arms, and the other end of each of the TPU strips is perpendicularly connected to the other of the TPU connecting arms, wherein the TPU strips play a bonding role and the TPU connecting arms play a connecting role; the spacing between adjacent TPU strips in the TPU-1 is the same and equal to 3 times the width of the TPU strip (the width of each of the TPU strips is the same, and the width of the TPU strip is equal to the side length of the honeycomb unit), the spacing between adjacent TPU strips in the TPU-2 is the same and equal to 3 times the width of the TPU strip (the width of each of the TPU strips is the same), and the spacing between adjacent TPU strips in the TPU-1 is the same as the spacing between adjacent TPU strips in the TPU-2 (the width of each of the TPU strips in the TPU-1 is the same as the width of each of the TPU strips in the TPU-1), when the number of layers of the laser-induced graphene substrate in the laser-induced graphene smart honeycomb structure material is ≥3 layers, the laser-induced graphene substrate (LIGP), the TPU-1 and the TPU-2 are stacked and assembled together in an interleaved order to obtain an assembly (TPU / LIGPs); taking 6 layers of LIGP as an example, 3 layers of TPU-1 and 2 layers of TPU-2 are required, and the stacking order followed by the three is LIGP / TPU-1 / LIGP / TPU-2 / LIGP / TPU-1 / LIGP / TPU-2 / LIGP / TPU-1 / LIGP, as shown in a of Figure 10 In the embodiments of the present application, the thermoplastic film is taken as an example of TPU film, specifically, the TPU film is cut to obtain two structures of cut TPU, which are defined as TPU-1 and TPU-2 respectively; both the TPU-1 and the TPU-2 are in the shape of a ladder, including two TPU connecting arms in parallel distribution and a plurality of TPU strips (i.e. corresponding to the thermoplastic core strip adhesive) in parallel distribution, one end of each of the TPU strips is perpendicularly connected to one of the TPU connecting arms, and the other end of each of the TPU strips is perpendicularly connected to the other of the TPU connecting arms, wherein the TPU strips play a bonding role and the TPU connecting arms play a connecting role; the spacing between adjacent TPU strips in the TPU-1 is the same and equal to 3 times the width of the TPU strip (the width of each of the TPU strips is the same, and the width of the TPU strip is equal to the side length of the honeycomb unit), the spacing between adjacent TPU strips in the TPU-2 is the same and equal to 3 times the width of the TPU strip (the width of each of the TPU strips is the same), and the spacing between adjacent TPU strips in the TPU-1 is the same as the spacing between adjacent TPU strips in the TPU-2 (the width of each of the TPU strips in the TPU-1 is the same as the width of each of the TPU strips in the TPU-1), when the number of layers of the laser-induced graphene substrate in the laser-induced graphene smart honeycomb structure material is ≥3 layers, the laser-induced graphene substrate (LIGP), the TPU-1 and the TPU-2 are stacked and assembled together in an interleaved order to obtain an assembly (TPU / LIGPs); taking 6 layers of LIGP as an example, 3 layers of TPU-1 and 2 layers of TPU-2 are required, and the stacking order followed by the three is LIGP / TPU-1 / LIGP / TPU-2 / LIGP / TPU-1 / LIGP / TPU-2 / LIGP / TPU-1 / LIGP, as shown in a of

[0049] After obtaining the assembly, the assembly is hot-pressed to obtain a laminate. In the present application, the hot-pressing conditions include: the temperature is preferably 80-200°C, more preferably 100-150°C, and further preferably 130-140°C; the pressure is preferably 1-10 MPa, more preferably 3-7 MPa, and further preferably 4-5 MPa; the holding time is preferably 1-1000 min, more preferably 60-480 min, and further preferably 300-360 min. The holding time is selected according to the number of layers of the laser-induced graphene substrate, for example, when the number of layers of the laser-induced graphene substrate is 2, the holding time is preferably 30 min or more to achieve excellent bonding effect, and when the number of layers of the laser-induced graphene substrate is 20, the holding time is preferably 360 min to achieve excellent bonding effect, under the conditions of a hot-pressing temperature of 140°C and a pressure of 5 MPa.

[0050] After obtaining the laminate, the laminate is stretched to obtain a preformed honeycomb body. The laminate is preferably cut to a suitable width according to actual needs, and then stretched and expanded into a honeycomb structure with the aid of a mold to obtain a preformed honeycomb body. The cutting is preferably laser cutting or cutting bed cutting. The laser cutting conditions include: the laser power is preferably 1-25 W, and more preferably 2 W; the laser running speed is preferably 2.54-50.8 mm / s, and more preferably 12.7 mm / s; the PPI is preferably 1-1000, and more preferably 500; and the defocusing distance is preferably ≤4 mm, and more preferably 0 mm (i.e., cutting under focusing). The mold is preferably assisted by a screw and an acrylic plate to achieve stretching. Specifically, a first screw is fitted into the hole on one side of the laminate, and the first screw is fixed on the acrylic plate. Then, a second screw is fitted into the hole on the opposite side of the laminate, and the second screw is fixed on the acrylic plate after the honeycomb cell size and shape meet the requirements, thereby obtaining a honeycomb structure assisted by the screw and the acrylic plate, i.e., a preformed honeycomb body. At this time, the preformed honeycomb body will restore to the original stacked layer structure once it is removed from the screw, so that the preformed honeycomb body is reinforced and formed by subsequent impregnation and curing, i.e., no longer relying on the fixed support of the mold, becoming an independent self-supporting honeycomb structure. In the present application, the shape of the honeycomb cell is affected by the stretching expansion degree (represented by the expansion angle θ, as shown in FIG. d), and specifically, the relationship between the shape of the honeycomb cell and θ is: a hexagonal shape when θ < 60°, a regular hexagonal shape when θ = 60°, a quadrilateral shape when 60° < θ < 90°, and a square shape when θ = 90°. Figure 10

[0051] ​After obtaining the preformed honeycomb body, the preformed honeycomb body is impregnated with a resin material to obtain an impregnated body. In the present application, the resin material used for impregnation is preferably a thermosetting resin, which preferably includes one or more of epoxy resin, polyester resin, phenolic resin, melamine formaldehyde resin, furan resin, polybutadiene resin and silicone resin, more preferably epoxy resin; the epoxy resin preferably includes tetraglycidyl diaminodiphenylmethane (AG80) epoxy resin or bisphenol A epoxy resin, more preferably bisphenol A epoxy resin; the bisphenol A epoxy resin preferably includes IN2 epoxy resin or E51 epoxy resin, more preferably IN2 epoxy resin; the epoxy value of the AG80 epoxy resin is preferably 0.75-0.85, the epoxy value of the E51 epoxy resin is preferably 0.48-0.54, and the epoxy value of the IN2 epoxy resin is preferably 0.23-0.38. In the present application, when the IN2 epoxy resin is used, the curing agent used is preferably AT30 curing agent or AT50 curing agent, more preferably AT30 curing agent. In order to make the resin material have better flowability, the present application preferably uses the resin material after dilution; the diluent used for dilution preferably includes acetone, ethyl acetate or isopropyl alcohol; specifically, when the epoxy resin is used, the diluent used is preferably acetone. In the present application, according to the weight ratio = (epoxy resin + curing agent) / (epoxy resin + curing agent + diluent) = 0.1-100wt%, the concentration of the dilution solution obtained after dilution is preferably 5-50wt%; the mass ratio of the epoxy resin to the curing agent is preferably 10:3. The present application preferably mixes the epoxy resin, the curing agent and the diluent to obtain a dilution solution; the preformed honeycomb body (containing screws and acrylic plates) is immersed in the dilution solution to achieve the impregnation to obtain an impregnated body; the immersion time is preferably 0.01-5h, more preferably 0.1-0.25h.

[0052] After obtaining the impregnated body, the impregnated body is cured to obtain the laser-induced graphene smart honeycomb structure material (3DLIG-HC). In the present application, the curing conditions include: the temperature is preferably 25-80℃, more preferably 50-70℃, and further preferably 60℃; the time is preferably 5-48h, more preferably 7-10h, and further preferably 8h.

[0053] The present application provides a laser-induced graphene smart honeycomb structure material prepared by the preparation method described in the above technical solution. In the present application, the laser-induced graphene smart honeycomb structure material is specifically formed by a laser-induced graphene base, a thermoplastic core strip glue and a cured resin material, wherein the thermoplastic core strip glue is used for selectively misaligned bonding of adjacent laser-induced graphene bases to form a honeycomb structure; and the resin material is used for reinforcing the honeycomb structure. In the present application, the honeycomb structure is specifically formed by an array of honeycomb units.

[0054] The present application provides a kind of intelligent sandwich honeycomb structure material (Sandwich HC), including the laser-induced graphene intelligent honeycomb structure material described in the above technical solution and the skin of the upper surface and the lower surface of the laser-induced graphene intelligent honeycomb structure material.It is described in the present application that the skin can select any hard or soft sheet, plate or film, preferably carbon fiber prepreg plate, glass fiber prepreg plate, laser-induced graphene paper (LIGP), laser-induced graphene paper / IN2 epoxy resin composite film (LIGP / IN2 film, specifically LIGP is impregnated with IN2 epoxy resin and the composite film obtained after curing), epoxy plate, PI film or wood board.In the present application, the thickness of the skin is preferably 50-2000 μm, more preferably 1000 μm.The skin described in the present application is preferably attached to the upper surface and the lower surface of the laser-induced graphene intelligent honeycomb structure material, more preferably adhered to the upper surface and the lower surface of the laser-induced graphene intelligent honeycomb structure material;The adhesive used for adhesion preferably includes double-sided tape, glue, foamed polyurethane glue or epoxy hot glue, more preferably epoxy hot glue.

[0055] The present application provides the application of the laser-induced graphene intelligent honeycomb structure material described in the above technical solution or the intelligent sandwich honeycomb structure material described in the above technical solution in the fields of electric heating, ice prevention, ice removal, high temperature warning, flame retardation, pressure sensing, vibration monitoring, electromagnetic shielding and stealth.

[0056] The technical solutions in the present application will be clearly and completely described below in conjunction with the embodiments in the present application.It is obvious that the described embodiments are only a part of the embodiments of the present application, not all the embodiments.Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0057] In the following examples, the laser used for laser induction is a 10.6 μm carbon dioxide infrared laser with a rated power of 25 W, using a filling mode, and the full load speed is 1270 mm / s;The polyimide (PI) paper used is purchased from Changchun Gaoci Polyimide Material Co., Ltd., with a thickness of 90 μm;The thermoplastic polyurethane (TPU) film used is purchased from Dongguan Xinrui Plastic Products Co., Ltd., with a thickness of 50 μm;The resin material used is IN2 epoxy resin (epoxy value is 0.23-0.38), the curing agent is AT30 curing agent, and the diluent used is acetone.

[0058] Example 1: Establishment of processing parameters of laser-induced graphene paper (LIGP)

[0059] Laser-induced double-sided polyimide paper is used to obtain LIGP; the laser-induced conditions include: laser power of 7.5-15W, laser running speed of 635mm / s, pixels per inch (PPI) of 500, and defocus distance (DL) of 0-4mm.

[0060] Figure 1 This image shows a schematic diagram and scanning electron microscope (SEM) image of the LIGP cross-section. The laser-induced conditions include: laser power of 11W, laser speed of 635mm / s, PPI = 500, and DL = 3mm. Specifically, laser processing of both sides of the PI paper yields double-sided laser-induced LIGP. Because the laser ablation depth is controllable, a residual PI layer is ensured in the middle, thus maintaining certain mechanical properties of the LIGP. The SEM image shows that the LIGP cross-section consists of three parts: the upper and lower LIG layers, and the residual PI layer in the middle.

[0061] Figure 2 The images show scanning electron microscope (SEM) images, transmission electron microscope (TEM) images, Raman spectra, XRD patterns, and EDS patterns of the PI paper and LIGP. The laser-induced conditions include: laser power of 11W, laser speed of 635mm / s, PPI = 500, and DL = 3mm. Figure 2 In the image, 'a' represents the scanning electron microscope (SEM) image (top) and transmission electron microscope (TEM) image (bottom) of LIGP. The results show that the LIGP surface exhibits a porous morphology. The high-magnification TEM image reveals that LIGP has a few-layer graphene structure with an interlayer spacing of approximately 3.35 Å, which corresponds to the (002) crystal plane of laser-induced graphene (LIG). Figure 2 b represents the Raman spectrum (top) and XRD pattern (bottom) of PI paper and LIGP. From the comparison of the Raman spectra above, it can be seen that LIG presents three characteristic peaks corresponding to the D peak, G peak and 2D peak respectively, which proves the existence of graphene structure. From the XRD pattern below, it can be seen that LIG presents two (002) and (100) characteristic peaks, which proves the high-quality graphene structure in LIGP. Figure 2 The 'c' in the figure represents the EDS plot of LIGP, and the results show that the C content in LIGP is increased, with a C mass fraction as high as 97.5%. This fully demonstrates the existence of graphene structures in LIGP.

[0062] Figure 3 Scanning electron microscope (SEM) images of LIGP surfaces prepared under different laser power and defocusing distance conditions are shown. The laser-induced conditions include: laser power of 7.5–15 W (specifically 7.5 W, 10 W, 11 W, 12.5 W, and 15 W), laser speed of 635 mm / s, PPI = 500, and DL = 0–4 mm (specifically 0 mm, 1 mm, 2 mm, 3 mm, and 4 mm). Figure 3a corresponds to DL=0 mm, b corresponds to DL=1 mm, c corresponds to DL=2 mm, d corresponds to DL=3 mm, e corresponds to DL=4 mm. The results show that when the DL is the same, as the laser power increases, the porous structure in the LIGP is obvious, and the surface morphology roughness is improved; when the laser power is fixed, as the DL increases from 0 mm to 4 mm, the gully phenomenon in the LIGP is reduced, the surface morphology becomes more and more flat, and a flat LIG structure is presented.

[0063] Figure 4 Raman spectra of LIGPs prepared under different laser power conditions, wherein the laser-induced conditions include: the laser power is 7.5-15 W (specifically, 7.5 W, 8.5 W, 9.5 W, 10 W, 11 W, 12 W, 12.5 W, 13.5 W, 14.5 W, 15 W), the laser running speed is 635 mm / s, PPI=500, and DL=3 mm. Figure 4 a is the Raman spectrum of the LIGP prepared under different laser power conditions, and b is the integral ratio of the D peak and the G peak and the integral ratio of the 2D peak and the G peak calculated from the Raman spectrum. The results show that as the laser power increases, the D peak decreases, the 2D peak increases, the integral ratio of the D peak and the G peak decreases, and the integral ratio of the 2D peak and the G peak does not change obviously, which is maintained between 0.5 and 0.9, indicating that as the laser power increases, the graphene defect decreases and the graphene quality becomes higher; wherein the graphene quality improves as the laser power increases from 7.5 W to 11 W, and the graphene quality does not change much as the laser power increases from 11 W to 15 W.

[0064] Figure 5 Cross-section scanning electron microscope images of LIGPs prepared under different laser power conditions, wherein the laser-induced conditions include: the laser power is 7.5-15 W (specifically, 7.5 W, 8 W, 8.5 W, 9 W, 9.5 W, 10 W, 10.5 W, 11 W, 11.5 W, 12 W, 12.5 W, 13 W, 13.5 W, 14 W, 14.5 W, 15 W), the laser running speed is 635 mm / s, PPI=500, and DL=3 mm. The results show that as the laser power increases, the LIG layer thickness gradually increases, and the residual PI layer thickness decreases, and the specific thickness data is shown in Figure 6 .

[0065] Figure 6The quantification relationship diagram of the thickness of LIG layer and the thickness of residual PI layer in LIGP prepared under different laser power conditions, wherein the laser-induced conditions include: the laser power is 7.5-15 W (specifically 7.5 W, 8 W, 8.5 W, 9 W, 9.5 W, 10 W, 10.5 W, 11 W, 11.5 W, 12 W, 12.5 W, 13 W, 13.5 W, 14 W, 14.5 W, 15 W), the laser running speed is 635 mm / s, PPI = 500, and DL = 3 mm. The results show that, as the laser power increases from 7.5 W to 15 W, the thickness of the residual PI layer decreases from 76 ± 1.93 μm to 27 ± 2.77 μm; and the total thickness of the LIG layer increases from 53.1 ± 1.49 μm to 108.7 ± 3.74 μm.

[0066] Figure 7 The resistance test and mechanical property test results diagram of LIGP prepared under different laser power conditions, wherein the laser-induced conditions include: the laser power is 7.5-15 W (specifically 7.5 W, 8 W, 8.5 W, 9 W, 9.5 W, 10 W, 10.5 W, 11 W, 11.5 W, 12 W, 12.5 W, 13 W, 13.5 W, 14 W, 14.5 W, 15 W), the laser running speed is 635 mm / s, PPI = 500, and DL = 0-4 mm (specifically 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm). Figure 7 The diagram of the sheet resistance of LIG layer after single-side laser induction versus the power and DL in a (i.e. the sample used here is prepared by laser-induced single-side polyimide paper, and only contains the upper LIG layer and the lower PI layer), the results show that, as the laser power increases from 7.5 W to 15 W, the resistance gradually decreases; as the DL increases, the resistance gradually decreases; specifically, as the laser power increases from 7.5 W to 11 W, the resistance and the tensile strength decrease obviously, while as the laser power further increases from 11 W to 15 W, the resistance decreases slowly, and the tensile strength decreases slightly. Figure 7b in FIG. 2 is a graph showing the effect of different laser powers on the resistance and mechanical properties of LIGP (DL = 3 mm). The results show that as the laser power increases, the square resistance and in-plane resistance of LIGP decrease. In particular, when the laser power increases from 7.5 W to 11 W, the resistance of LIGP decreases sharply, and as the laser power further increases from 11 W to 15 W, the resistance decreases slowly. For the tensile strength, as the laser power increases, the tensile strength of LIGP decreases significantly. Specifically, when the laser power increases from 7.5 W to 11 W, the thickness of the residual PI layer decreases from 76 ± 1.93 μm to 32.5 ± 1.5 μm, and the tensile strength decreases significantly from 7.25 MPa to 2.4 MPa. When the laser power further increases to 15 W, the thickness of the residual PI layer decreases slowly to 27 ± 2.77 μm, and the tensile strength decreases slowly to 0.78 MPa.

[0067] According to the above results, in order to balance the quality of graphene, the electrical conductivity and mechanical properties of LIGP, the optimal conditions for laser induction are determined as follows: laser power is 11 W, laser running speed is 635 mm / s, PPI = 500, and DL = 3 mm, which are used for the preparation of LIGP in all subsequent examples.

[0068] Example 2: Preparation of laser-induced graphene smart honeycomb structure material (3D LIG-HC)

[0069] The thermal properties of the TPU film were tested, Figure 8 FIG. 2b is a graph showing the thermal performance analysis of the TPU film; Figure 8 a in FIG. 2a is a DSC test graph, and the results show that the glass transition temperature of the TPU film is 81.9°C, indicating that the molecular chain segment begins to move at this time. As the temperature increases to about 156°C, the melting temperature is reached, at which time the entire molecular chain is stretched and opened, and complete movement occurs. Figure 8 b in FIG. 2b is a TGA test graph, and the results show that there is almost no weight loss when the temperature is below 200°C, indicating that the TPU film can be used at a processing temperature of 200°C.

[0070] Figure 9 FIG. 3 is a flowchart for the preparation of 3D LIG-HC, Figure 9 a in FIG. 3a is a schematic diagram, and b is an actual operation diagram. The following will be described in detail with reference to Figure 9 The method for preparing 3D LIG-HC using LIGP and TPU film will be described in detail.

[0071] First, LIGP is prepared according to the laser induction technology in Example 1 (the laser induction conditions include: laser power is 11 W, laser running speed is 635 mm / s, PPI = 500, and DL = 3 mm);

[0072] The TPU film is cut by a laser cutting process (the laser cutting conditions include: laser power is 2W, laser running speed is 12.7mm / s, PPI=500, DL=0mm), to obtain two structures of cut TPU, which are defined as TPU-1 and TPU-2; the TPU-1 and TPU-2 are both in the shape of a ladder, including two TPU connecting arms in parallel distribution and a plurality of TPU bands in parallel distribution, one end of each TPU band is connected perpendicularly to one TPU connecting arm, the other end of each TPU band is connected perpendicularly to the other TPU connecting arm, the distance between adjacent TPU bands in the TPU-1 is the same (the width of each TPU band is the same), the distance between adjacent TPU bands in the TPU-2 is the same (the width of each TPU band is the same), and the distance between adjacent TPU bands in the TPU-1 is the same as the distance between adjacent TPU bands in the TPU-2 (the width of each TPU band in the TPU-1 is the same as the width of each TPU band in the TPU-1); the LIGPs, the TPU-1 and the TPU-2 are stacked and assembled together in an interleaved order to obtain an assembly (TPU / LIGPs); taking 6 layers of LIGPs as an example, 3 layers of TPU-1 and 2 layers of TPU-2 are needed, and the stacking order followed by the three is LIGP / TPU-1 / LIGP / TPU-2 / LIGP / TPU-1 / LIGP / TPU-2 / LIGP / TPU-1 / LIGP;

[0073] The TPU / LIGPs are placed in a hot press for hot pressing (the hot pressing temperature is 140℃, the pressure is 5MPa, and the holding time is 60min), to obtain a three-dimensional TPU / LIGPs laminate;

[0074] The three-dimensional TPU / LIGPs laminate is cut by a laser cutting process (the laser cutting conditions include: laser power is 2W, laser running speed is 12.7mm / s, PPI=500, DL=0mm), to obtain a long strip-shaped laminate, and the long strip-shaped laminate is pulled apart to show a hexagonal honeycomb structure;

[0075] A first screw is fitted into a hole on one side of the long strip-shaped laminate, and the first screw is fixed on an acrylic plate, then a second screw is fitted into a hole on the other side of the long strip-shaped laminate opposite to the one side, and the second screw is fixed on the acrylic plate after the long strip-shaped laminate is stretched to a size that meets the requirements of the honeycomb unit, to obtain a preformed honeycomb body;

[0076] IN2 epoxy resin, AT30 curing agent and acetone are mixed to obtain a diluent (the mass ratio of IN2 epoxy resin to AT30 curing agent is 10:3, and the concentration of the diluent, that is, the total concentration of IN2 epoxy resin and AT30 curing agent in the diluent, is 10wt%). The preformed honeycomb body (including screws and acrylic sheet) is immersed in the diluent (immersion time is 5min), and then cured (cured at 60℃ for 8h) to obtain 3D LIG-HC (a layer of skin can be attached to both the upper and lower surfaces of the 3D LIG-HC to form a sandwich smart honeycomb structure material, i.e., Sandwich HC).

[0077] Example 3: Structural Pre-design Principles of 3D LIG-HC

[0078] Figure 10 This is a pre-design schematic diagram of the 3D LIG-HC structure. Figure 10 In the diagram, 'a' shows a schematic diagram of the anisotropic direction of 3D LIG-HC and design drawings of two types of LIG / TPU layers; 'b' shows the relationship curve between the number of LIG layers and the number of honeycomb cells (pores); 'c' shows a schematic diagram of the molding process; 'd' shows a schematic diagram of the unfolding process of a pre-formed honeycomb structure formed by stretching 10 layers of LIGP; 'e' shows the relationship curve between the W direction (width) and L direction (length) of 3DLIG-HC; 'f' shows schematic diagrams of various graphitized clusters; and 'g' shows a schematic diagram of the processing route for triangular clusters in LIG / PI honeycomb. The following section will combine... Figure 10 Please provide a detailed explanation.

[0079] Figure 10 The anisotropic directions of the 3D LIG-HC are defined in section 'a'. The length direction represents the direction along the length of the LIG layer (L), the width direction represents the unfolding direction along the stacked layers (W), and the thickness direction represents the height direction of the cell (T). To form a regular hexagonal lattice, the width of each TPU strip is fixed to be equal to the side length of the hexagon, denoted as m, and the distance between two adjacent TPU strips is equal to 3m. The formation of each cell structure requires two types of TPU, denoted as TPU-1 and TPU-2, whose specific dimensions and TPU strip arrangement are as follows... Figure 10 As shown in a. When the total length of LIGP is TL, the relationship between the total length TL and the side length m of the hexagon is TL=m(4a+1) (where a represents the number of holes that can be formed by two LIGP sheets, and a is a positive integer greater than or equal to 1, such as 1, 2, 3, 4...). As the number of LIGP layers (n) changes, the number of holes (CQ) in the obtained 3D LIG-HC also changes accordingly. Mathematical models are established based on whether the number of LIGP layers is odd or even, as shown in equation (1):

[0080]

[0081] Thus, Figure 10 The variation of the cell number CQ of the 3D LIG-HC composed of four types of LIGP (TL = 5m, 9m, 13m and 17m) is summarized in b. To better explain the relationship therein, as shown in c, taking 10 layers of LIGP with TL of 17m (i.e. a = 4) as an example, 9 layers of TPU, i.e. 5 layers of TPU-1 and 4 layers of TPU-2, are alternately inserted into adjacent LIGP. After hot pressing, the places provided with TPU are bonded, and the places without TPU are not bonded. With the expansion of the stacked layers, the honeycomb structure formed by 5 rows of 4 cells and 4 rows of 3 cells is shown, i.e. CQ = 32. Figure 10 In addition to studying the number of cells, the shape of the cells formed by expansion is also studied in this embodiment.

[0082] The process of 10 layers of stacked layers from their original stacked state to fully expanded state is dynamically presented in d. With the change of the expansion angle (θ), the cell shape is in turn: hexagonal-like (θ < 60°), regular hexagonal (θ = 60°), quadrilateral-like (60° < θ < 90°), regular quadrilateral (θ = 90°). According to the expansion angle (θ), the number of LIGP layers (n) and the total length of LIGP (TL) variables, the function models about the length (L) and width (W) of the 3D LIG-HC are established, as shown in equations (2) and (3): Figure 10 W = n x m x sinθ (2)

[0083]

[0084] Based on the above equations,

[0085] The variation of the length (L) and width (W) of the 3D LIG-HC composed of four types of LIGP (TL = 5m, 9m, 13m and 17m) is summarized in e. When the width W of the 3D LIG-HC is equal to 0nm, 0.866nm and 1nm respectively, it represents three specific cell shapes, i.e. the original stacked layer structure (W = 0nm), the regular hexagonal structure (W = 0.866nm) and the regular quadrilateral structure (W = 1nm); the hexagonal cell is between 0nm and 0.866nm, and the quadrilateral-like cell is between 0.866nm and 1nm. Figure 10 Regarding the preparation of LIGP, since laser has the advantage of selective processing, both bulk laser treated LIGP and selected graphitized LIG / PI can be obtained by design, which are used to form LIG / PI-HC honeycomb with graphene cluster structure.

[0086] Figure 10 ​Four types of 3D LIG-HC with graphene cluster structures were designed, including triangular graphene clusters, rectangular graphene clusters, parallelogram graphene clusters, and rhombic graphene clusters. Based on the pre-designed drawings, specific areas of the PI paper were laser-induced to form specific graphene cluster structures. Figure 11 The image 'g' illustrates the design principle of the third LIG / PI layer in the triangular cluster structure. Specifically, the PI paper is divided into 13 intervals, and laser induction is performed in specific areas on the front and back of the PI paper to ensure the formation of the triangular cluster structure.

[0087] Example 4: Structural pre-design principle of 3D LIG / PI-HC based on multiple graphene cluster combinations

[0088] Figure 11 This is a pre-design schematic diagram of a 3D LIG / PI-HC structure with multi-unit graphene clusters. Specifically, the schematic diagrams of different layers in a 3D LIG / PI-HC structure with multiple graphene cluster combinations are shown below. Figure 11 As shown in a; based on pre-designed drawings, a hybrid LIG / PI-HC with various graphene clusters was finally obtained, such as Figure 12 As shown in b, it includes single-cell clusters, double-cell clusters, triple-cell clusters, six-cell clusters, and ten-cell clusters. In this embodiment, all honeycomb structure processing parameters are consistent. Laser induction conditions include: laser power of 11W, laser speed of 635mm / s, PPI = 500, and DL = 3mm; hot-pressing conditions include: temperature of 140℃, pressure of 5MPa, and holding time of 60min; impregnation conditions include: diluent concentration of 10wt%; conditions not mentioned are the same as in Example 2.

[0089] Example 5: Demonstration of diverse 3D LIG-HC structures

[0090] Figure 12 This diagram illustrates diverse 3D LIG-HC structures, where the honeycomb structure processing parameters (laser-induced conditions, hot-pressing conditions, and impregnation conditions) are consistent with those in Example 4. Compared to traditional smart cell assembly technologies, this invention allows for the design and assembly of highly free-form smart cells by changing a series of adjustable parameters (including the size and number of LIGP layers, the cutting distance of stacked layers, the width of the TPU strip, and the degree of stretching). Firstly, the overall size of the 3D LIG-HC is adjustable, thanks to the scalable size, unlimited stacking quantity, and cutting level of LIGP. For example, Figure 12 In the middle, 'a' is achieved by stacking 24 layers of 185×50mm material. 2 The LIGP of the specified size was constructed to obtain a size of 150×100mm. 23D LIG-HC with large surface area. Ideally, the maximum size of LIGP reaches 600 x 300 mm by using the maximum processing area of current laser instruments 2 A 3D LIG-HC with a surface area of 440 x 433 mm can be constructed with 100 stacked layers 2 Secondly, the cutting distance of the stacked layers is adjustable. As shown in b of Figure 12 , the 3D LIG-HC can be expanded in thickness from 3 mm to 10 mm. Thirdly, in addition to the overall size, the side length and shape of the internal cell of the 3D LIG-HC can also be precisely regulated by design. Specifically, the side length of the cell can be regulated by using TPU tapes with different widths, as shown in c of Figure 12 , which shows four 3D LIG-HCs with different cell side lengths (5 mm, 4 mm, 3 mm, and 2 mm, respectively); by controlling the expansion distance (i.e., the degree of stretching expansion) of the 8-layer stacked layers to be 20 mm, 34.6 mm, 38 mm, and 40 mm, respectively, the internal cell shapes of the resulting honeycomb structures are correspondingly hexagonal, regular hexagonal, quasi-quadrangular, and regular quadrangular. Meanwhile, as shown in e of Figure 12 , by selectively laser-induced graphitization processing of PI, honeycomb structure 3D LIG / PI-HC with various graphene clusters can be obtained. In addition, laser cutting operations can trim the 3D LIG-HC into other shapes. Further, as shown in f of Figure 13 , by assembling a 3D LIG-HC model with the shape of an airplane wing (surface area of 3234 mm 2 , thickness of 5 mm) with a composite skin, a smart sandwich honeycomb structure material (Sandwich HC) can be formed.

[0091] Example 6: Demonstration of Sandwich HC structures with different skin structures

[0092] Figure 13 are demonstration diagrams of Sandwich HC structures with different skin structures, in which the honeycomb structure processing parameters (laser-induced conditions, hot-pressing conditions, and impregnation conditions) in this example are consistent with those in Example 4. As shown in Figure 14 , it demonstrates three Sandwich HC structures, respectively, with fiberglass prepreg skin on the upper and lower surfaces of 3D LIG-HC, with fiberglass prepreg skin on the upper and lower surfaces of 3D LIG / PI-HC, and with carbon fiber prepreg skin on the upper and lower surfaces of 3D LIG-HC.

[0093] Example 7: Large deformation tolerance, light weight, and load-bearing characteristics of 3D LIG-HC

[0094] Figure 14Figure 3 is a diagram of the large deformation tolerance, light weight, and load bearing characteristics of the 3D LIG-HC. Figure 3a is a diagram of the large deformation tolerance of the 3D LIG-HC, wherein the honeycomb structure processing parameters (laser-induced conditions, hot-pressing conditions, and impregnation conditions) are consistent with those in Example 4, refer to the parameter definitions in Example 3, m = 5 mm, n = 10, and θ = 60°. The results show that the 3D LIG-HC can be stretched, pressed, and even bent to nearly 360° to a great extent. Figure 14 Figure 3a is a diagram of the large deformation tolerance of the 3D LIG-HC, wherein the honeycomb structure processing parameters (laser-induced conditions, hot-pressing conditions, and impregnation conditions) are consistent with those in Example 4, refer to the parameter definitions in Example 3, m = 5 mm, n = 10, and θ = 60°. The results show that the 3D LIG-HC can be stretched, pressed, and even bent to nearly 360° to a great extent. Figure 14 Figure 3b is a diagram of the light weight characteristics of the 3D LIG-HC, wherein the honeycomb structure processing parameters (laser-induced conditions, hot-pressing conditions, and impregnation conditions) are consistent with those in Example 4, refer to the parameter definitions in Example 3, m = 2 mm, n = 10, and θ = 60°. The results show that the 3D LIG-HC can stand on the top of the bluestem grass. Figure 15 Figure 3c is a diagram of the load bearing characteristics of the 3D LIG-HC, wherein the total concentration of the epoxy resin and the curing agent in the diluent used for impregnation is 50 wt%, the other honeycomb structure processing parameters (laser-induced conditions, hot-pressing conditions) are consistent with those in Example 4, refer to the parameter definitions in Example 3, m = 5 mm, n = 22, and θ = 60°. The results show that the 3D LIG-HC can bear the weight of an adult of 66.5 kg without breaking or deforming, indicating that it has excellent load bearing capacity.

[0095] Example 8: Study on the formability of the 3D LIG-HC

[0096] Figure 15 Figure 4 is a diagram of the formability of the 3D LIG-HC. In this example, the laser-induced conditions include: laser power of 11 W, laser running speed of 635 mm / s, PPI = 500, and DL = 3 mm; the hot-pressing conditions include: temperature of 120-180 °C, pressure of 2-10 MPa, and holding time of 3-390 min; and the conditions not mentioned are the same as those in Example 4. The effects of the hot-pressing conditions on the bonding strength of the LIGP are described in detail below.

[0097] First, the bonding strength of two layers of LIGP was studied by forming a simple LIGP-TPU-LIGP structure. The hot-pressing pressure was fixed at 5 MPa, and the holding time was 20 min. The different microstructures of the LIG-TPU-LIG processed under different hot-pressing temperatures (120 °C, 140 °C, 160 °C, and 180 °C) were studied, as shown in Figure 15As shown in image a (SEM), at 120℃, the thickness of the TPU interface is 46.5 μm, close to the original interface (50 μm), indicating poor TPU flowability, which is not conducive to fusion with the LIG layer. When the temperature rises to 140℃, the thickness decreases significantly to 28.5 μm, meaning that the flowability is improved, which is beneficial for interface integration. However, with further increases in temperature, the TPU interface almost (at 160℃) or completely (at 180℃) disappears, indicating that the TPU flowability is too high, and it randomly disperses to other areas, which is not conducive to adhesion. To verify the experimental observations, as shown in... Figure 15 As shown in b, the fracture energy (Gc) of double-layer or multi-layer LIG-TPU-LIG samples during the tear test is evaluated with reference to the classic tear test model. The experimentally determined tear force is converted to Gc. Figure 15 The expression 'c' in the figure compares the functional relationship between fracture energy and temperature. Specifically, Gc exhibits a two-state effect; as the temperature increases from 120℃ to 140℃, Gc initially increases from 96.5±6.6 J / m. 2 Increased to 129.9±4.5 J / m 2 Then it gradually decreases. By further increasing the temperature to 170℃, the trend reaches 18.7±3.2 J / m. 2 As in Figure 15 The temperature-dependent fracture energy discussed in section a can well explain the evolving microstructure. Figure 15 The illustration in Figure c further confirms that only tear-failed samples at temperatures between 130°C and 140°C can exhibit LIG / PI cores (Gc > 100 J / m). 2 This indicates the formation of an effective adhesive interface, with effective failure rather than simple debonding occurring during the failure mode. Therefore, 140°C is the optimal temperature for hot-pressing multilayer LIG-HC.

[0098] In addition to temperature, this embodiment further investigates the effect of hot pressing pressure (2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa) on bonding strength by fixing the hot pressing temperature (140℃) and the heat holding and pressure holding time (20min). Figure 15 In the image, d represents the SEM image, and e represents the tear test result. Both images show a sandwich microstructure with similar TPU thickness (29.7±3.4 μm) and almost identical fracture energy (132.8±5.2 J / m). 2 This indicates that the hot pressing pressure has little effect on the bonding strength.

[0099] In this example, the effect of holding time (3 min, 5 min, 10 min, 20 min, 30 min, 60 min) on the bonding strength was further investigated by fixing the hot-pressing temperature (140 °C) and the hot-pressing pressure (5 MPa). Figure 15 The f in g clearly shows that the TPU thickness decreases from 48.9 pm to 26.4 pm as the hot-pressing time is prolonged from 3 min to 30 min; there is almost no change in the TPU thickness (28.1 pm) by further prolonging the hot-pressing time to 60 min. Figure 16 The g in g confirms the observation that the fracture energy of the 10 min hot-pressing exceeds 100 J / m 2 (116.6 ± 8.8 J / m 2 ), representing the formation of a strong bond; by prolonging the hot-pressing time to 30 min and 60 min, the fracture energy stabilizes at 145.1 ± 2.1 J / m 2 , which means that 30 min is sufficient to achieve the optimal bonding performance.

[0100] Considering that there might be differences in the thermal conduction of the stacked structures with different numbers of layers, the number of layers should be a non-negligible factor in determining the bonding quality. In this example, the effect of the number of layers on the bonding strength was investigated by performing the tearing test on LIG samples with 2-20 layers, Figure 16 The h in g compares the fracture energy related to the hot-pressing time, and the results show that all the curves follow a similar trend of increasing and then stabilizing as the hot-pressing time elapses, and the fracture energy curves obviously move to longer hot-pressing times as the number of layers accumulates from low to high, indicating that the hot-pressing time (100 J / m 2 ) to achieve effective bonding also increases as the number of layers increases. Figure 16 The i in g summarizes the hot-pressing time window for different numbers of layers to ensure the efficient and effective bonding performance of the stacked layers, and the results show that as the number of layers increases from 2 to 20, the hot-pressing time window for forming effective bonding changes from 10-30 min to 300-360 min.

[0101] Example 9: Multifunctional performance of 3D LIG-HC

[0102] Figure 16For the results of multifunctional performance test of 3D LIG-HC, the total concentration of epoxy resin and curing agent in the diluent used for impregnation in the preparation of the honeycomb structure in this embodiment was 5-50 wt% (5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%), and the honeycomb structure processing parameters (laser-induced conditions and hot-pressing conditions) were consistent with those in Example 4. Referring to the parameter definitions in Example 3, m = 2 mm, n = 10, and θ = 60°. That is, by adjusting the diluent concentration (5-50 wt%) in the impregnation process, the performance of 3D LIG-HC was studied.

[0103] As shown in a of Figure 16 , as the diluent concentration increased from 5 wt% to 50 wt%, the density of the single-layer LIGP / IN2 film increased from 0.67 ± 0.03 g / cm 3 to 1.03 ± 0.05 g / cm 3 , while the density of the 3D LIG-HC increased from 0.058 ± 0.002 g / cm 3 to 0.181 ± 0.009 g / cm 3 , which was much smaller than that of the single-layer LIGP / IN2 film. Here, the single-layer LIGP / IN2 film was prepared by laser-induced double-sided laser-induced double-sided polyimide paper to obtain LIGP (laser-induced conditions included: laser power was 11 W, laser running speed was 635 mm / s, PPI = 500, DL = 3 mm); the LIGP was impregnated in the diluent (concentration was 5-50 wt%) for 5 min, and then cured (cured at 60°C for 8 h) to obtain the single-layer LIGP / IN2 film

[0104] Figure 16 b of compares the shear strength and shear modulus along the L direction and the W direction, and the results show that, in addition to the positive effect of the diluent concentration (5-50 wt%) on the strength and modulus, the L-direction strength (0.46 ± 0.09 MPa to 2.66 ± 0.06 MPa) or modulus (8.53 ± 0.27 MPa to 20.4 ± 0.99 MPa) always exceeds the corresponding strength (0.15 ± 0.08 MPa to 2.14 ± 0.18 MPa) or modulus (1.91 ± 0.10 MPa to 18.15 ± 1.52 MPa) tested along the W direction, because the interlayer interface tends to debond when the shear force is loaded along the W direction, resulting in lower shear strength along the W direction.

[0105] As shown in a of Figure 16As shown in c, for anisotropic compressive properties, the compressive strength in the L direction (0.84±0.56 kPa to 35.95±2.78 kPa) and W direction (1.02±0.41 kPa to 19.63±1.75 kPa) shows that the compressive strength increases with the increase of diluent concentration (5 to 50 wt%).

[0106] Since the T-axis compressive strength is the main direction of load-bearing capacity of a honeycomb structure... Figure 16 The figure d represents the T-axis compressive properties of different 3D LIG-HCs. The force-displacement curves for a representative 3D LIG-HC (diluted at 30 wt%) are shown below. Figure 16 As shown in the illustration in section d, it follows a standard three-stage transformation similar to that of traditional aramid honeycomb: elastic deformation, compression deformation, and densification. Moreover, as... Figure 16 The results show that as the diluent concentration increases from 5 wt% to 50 wt%, the compressive strength increases from 0.25 ± 0.02 MPa to 6.51 ± 0.43 MPa, confirming that the T-direction compressive performance is superior to the L- and W-direction compressive performance.

[0107] like Figure 16 As shown by the top curve in the figure, with the increase of diluent concentration, energy absorption (Ea) again shows an upward trend from 0.3 kJ to 5.1 kJ. Besides the excellent weight reduction effect brought about by low density, Figure 16 The specific energy absorption in the bottom curve of the e-type curve is mainly in the range of 2.4 kJ / g to 14.2 kJ / g. This is in contrast to commercial applications. Compared to traditional cellular systems, smart cells supporting LIG can exhibit comparable or even superior performance, with comprehensive shear, compression, and energy absorption characteristics (H. Zhou, P. Xu, S. Xie, Z. Feng, D. Wang, Compos. Struct. 2018, 185, 524).

[0108] Besides mechanical properties, considering multifunctional applications, quantifying anisotropic electrical and piezoresistive properties is also important. For example... Figure 16As shown in f, with increasing dilution concentration (from 5 wt% to 50 wt%), the resistance in the W direction (602.19 ± 64.85 Ω to 2098.93 ± 32.57 Ω) was consistently higher than that in the L direction (188.97 ± 8.98 Ω to 503.74 ± 8.96 Ω) and the T direction (9.57 ± 1.78 Ω to 251.49 ± 17.7 Ω); furthermore, the conductivity in the W direction (0.33 ± 0.02 S / m to 0.05 ± 0.01 S / m) was again lower than that in the L direction (1.06 ± 0.07 S / m to 0.39 ± 0.05 S / m) and the T direction (1.34 ± 0.08 S / m to 0.11 ± 0.02 S / m), which is attributed to the W direction hindering electron transport. Based on these characteristics, 3D LIG-HC exhibits anisotropic electrical properties, which is the foundation for intelligent sensing applications.

[0109] Anisotropic piezoresistive properties in Figure 17 The concept of g is discussed further. By applying cyclic compressive deformation in all three directions while monitoring real-time resistance changes, the inset shows sensing data for representative samples, where resistance decreases or recovers synchronously with the loading or unloading of mechanical deformation. By evaluating all sensitivity factor (GF) values, diluent concentration again shows an adverse effect: increasing diluent concentration and resin particle content results in lower GF. This phenomenon can be explained by the variability of the conductive network disrupted by a certain degree of mechanical strain. With lower resin material content, the collapse of incompletely permeated residual pores / voids occurs more frequently, creating more conductive pathways, and vice versa. Specifically, while the GF in the T direction decreased from 13.5 ± 2.0 to 2.7 ± 0.38 as the diluent concentration increased from 10 wt% to 50 wt%, it was significantly higher than the GF in the L direction (1.29 ± 0.16 to 0.24 ± 0.02) and the GF in the W direction (2.50 ± 0.23 to 0.23 ± 0.04).

[0110] With its excellent mechanical and electrical properties, 3D LIG-HC shows great promise for electromagnetic wave shielding and absorption. Based on the differences in electromagnetic mechanisms, this embodiment designs two structures to explore their electromagnetic properties, including a 3D LIG-HC structure and a Sandwich HC structure. The skin used in the Sandwich HC structure is LIGP (laser processing parameters include: laser power of 11W, laser speed of 635mm / s, PPI=500, DL=3mm). Figure 17The electromagnetic interference (EMI) shielding performance of 3D LIG-HC and Sandwich HC was compared when the diluent concentration increased from 5 wt% to 50 wt%. The results showed that the total EMI shielding efficiency of Sandwich HC (37.6 dB to 20.5 dB) was consistently higher than that of 3D LIG-HC (9.87 dB to 6.79 dB). This was attributed to the presence of the LIGP skin, which avoids magnetic leakage and increases reflection loss, thereby simultaneously enhancing the reflection and absorption of electromagnetic waves.

[0111] Besides electromagnetic shielding properties, electromagnetic absorption is also important in load-bearing structures and electromagnetic wave stealth applications. For example... Figure 18 As shown in Figure i, as the diluent concentration increases from 5 wt% to 50 wt%, the reflection loss of 3D LIG-HC (-1.6 dB to -2.3 dB) is consistently higher than that of Sandwich HC (-8.43 dB to -20.01 dB). Therefore, for the 3D LIG-HC structure, low conductivity reduces reflection loss, and the customizable structure improves impedance matching characteristics, which is beneficial for electromagnetic wave absorption. 3D LIG-HC possesses controllable and excellent absorption properties, making it suitable for stealth applications. Sandwich HC structures, due to their excellent conductivity and micro-irregular porous conductive network, can shield electromagnetic waves by increasing reflection loss and multiple reflection losses, making them a promising electromagnetic shielding material.

[0112] Example 10: 3D LIG-HC applied to anti-icing and de-icing

[0113] Figure 18 The image shows the test results of 3D LIG-HC applied to anti-icing and de-icing. In this embodiment, all honeycomb structure processing parameters (laser induction conditions, hot pressing conditions, and impregnation conditions) are consistent with those in Example 4; referring to the parameter definitions in Example 3, m = 2mm, n = 10, θ = 60°. Figure 19 As shown, by inputting 0.1–5W of power into the conductive 3D LIG-HC, the wing model is instantly heated, with the temperature precisely controlled between 28.8 and 161°C. Therefore, the increased temperature can prevent cloud / raindrop capture or remove accumulated ice. For example, by freezing the entire wing in a large block of ice, a continuous input power of 3.5W and a heating temperature of 110°C can reduce the ice from 14.5g to 5.4g within 3 minutes, a reduction of 62.7wt%, demonstrating excellent de-icing performance.

[0114] Example 11: 3D LIG-HC applied to high temperature early warning monitoring

[0115] Figure 19For the test result graph of 3D LIG-HC applied to high-temperature early warning monitoring, all the honeycomb structure processing parameters (laser induction conditions, hot pressing conditions and impregnation conditions) in this embodiment are consistent with those in Embodiment 4; referring to the parameter definition in Embodiment 3, m = 2 mm, n = 10, and θ = 60°. As shown in FIG. 6, by enclosing the combustion flame with a temperature of about 1000°C onto the wing model, the resistance signal monitored by 3D LIG-HC in real time can accurately reflect the flame distance. As the distance gradually shortens from far to 30 cm, 20 cm, 10 cm and 5 cm, the resistance decreases by 4.7%, 9.1%, 17.1% and 23.4% respectively, indicating that the faithful record of the monitoring signal reaches the extreme heat distance, realizing high-temperature early warning before fatal damage occurs, and the resistance sharply decreases to -49.8%, and then rapidly increases to more than 300% when the flame distance is close to 0 cm. Figure 20

[0116] Embodiment 12: 3D LIG-HC applied to flame retardation

[0117] In addition to the heat early warning capability, the structure with a large amount of introduced graphene can theoretically improve the thermal stability of 3D LIG-HC, thereby enhancing the flame retardation performance. Figure 20 For the test result graph of 3D LIG-HC applied to flame retardation, all the honeycomb structure processing parameters (laser induction conditions, hot pressing conditions and impregnation conditions) of 3D LIG-HC in this embodiment are consistent with those in Embodiment 4; referring to the parameter definition in Embodiment 3, m = 2 mm, n = 10, and θ = 60°. As shown in FIG. 7, by keeping the heat flux at 50 kW / m Figure 20 2 The heat release rate (HRR) of 3D LIG-HC, polyimide honeycomb (PI-HC; the PI-HC is prepared according to the preparation process of 3D LIG-HC, except that LIGP is replaced by PI) and epoxy resin plate is compared; by quantification by cone calorimetry, the peak HRR (30.4 kW / m 2 ) of 3D LIG-HC is significantly lower than the peak HRR (219.5 kW / m 2 ) of pure epoxy resin, and is obviously superior to the PI-HC (38.2 kW / m 2 ), proving the excellent flame retardation performance thereof.

[0118] Embodiment 13: 3D LIG-HC applied to array sensing

[0119] Figure 20 ​​The image shows the test results of 3D LIG-HC applied to array sensing. In this embodiment, all the honeycomb structure processing parameters of 3D LIG-HC (laser induction conditions, hot pressing conditions, and impregnation conditions) are consistent with those in Example 4; referring to the parameter definitions in Example 3, m = 2mm, n = 10, θ = 60°. 3D LIG-HC has excellent piezoresistive sensing characteristics. Specifically, nine 3D LIG-HC sensing elements are arranged in a 3×3 equidistant pattern and fixed on a rigid plate to obtain a 3D LIG-HC array sensor, as shown below. Figure 20 Image 'a' shows a physical diagram of a 3D LIG-HC array sensor, where the electrodes of each 3D LIG-HC sensing element are connected via copper foil. (See image 'a'.) Figure 21 As shown in b, when a pair of scissors is placed on a 3D LIG-HC array sensor, the uneven distribution of gravity on the scissors will cause changes in the resistance signal. Figure 21 In section c, the gravity distribution of the scissors on the 3D LIG-HC array sensor was simulated using finite element analysis. The resistance values ​​of the nine 3D LIG-HC sensing elements were detected in real time using a programmable switch control system, and the resistance variation distribution diagram was further obtained, as shown in the figure. Figure 22 As shown in d, due to the greater gravity at the scissor head position, the resistance change of the 3D LIG-HC sensing element at that location is the largest, with ΔR / R0 approximately 0.41%. Moving downwards from the area of ​​greatest pressure, the resistance decreases diagonally, and the resistance change at the unloaded portion of the 3D LIG-HC array sensor is 0. This demonstrates that the piezoresistive array sensor exhibits high sensitivity for real-time, multi-position sensing, meeting the future development needs of intelligent manufacturing.

[0120] Example 14: 3D LIG-HC applied to stress detection in a two-element system

[0121] Figure 22 The image shows the stress detection results of 3D LIG-HC applied to a two-unit cell. In this embodiment, all the honeycomb structure processing parameters of 3D LIG-HC (laser induction conditions, hot pressing conditions, and impregnation conditions) are consistent with those in Example 4; referring to the parameter definitions in Example 3, m = 2mm, n = 10, θ = 60°. Figure 23 As shown, by assembling a 3D LIG-HC wing model with two isolated graphene clusters located in different regions, a weight of 100g was applied to any corresponding position to simultaneously monitor two sets of sensor signals. Clearly, when the weight was applied to position 1, only the resistance at position 1 changed instantaneously, with a resistance change rate of approximately 0.89%, and vice versa.

[0122] Example 15: 3D LIG-HC applied to frequency detection

[0123] Figure 23 For 3D LIG-HC application in frequency detection results, all the honeycomb structure processing parameters (laser-induced conditions, hot-pressing conditions, and impregnation conditions) of 3D LIG-HC in this embodiment are consistent with those in Example 4. Referring to the parameter definitions in Example 3, m = 2 mm, n = 10, and θ = 60°. In addition to the static load, as shown in Figure 23 , it shows the sensing response of the smart wing to different frequency vibrations. Specifically, from low frequency (0.1 Hz) to high frequency (5 Hz), the sensitive response of the smart honeycomb structure shows excellent cycle stability, indicating the ability to warn different frequency vibrations. The ability to perceive static and dynamic mechanical interference can endow 3D LIG-HC with great potential to monitor various abnormal flight states, such as bird strikes, atmospheric turbulence, and mechanical vibrations.

[0124] Example 16: 3D LIG-HC application in electromagnetic shielding and stealth

[0125] Figure 23 For 3D LIG-HC application in electromagnetic shielding and stealth test results, all the honeycomb structure processing parameters (laser-induced conditions, hot-pressing conditions, and impregnation conditions) of 3D LIG-HC in this embodiment are consistent with those in Example 4. Referring to the parameter definitions in Example 3, m = 2 mm, n = 10, and θ = 60°. In the Sandwich HC structure formed by the upper and lower surfaces of 3D LIG-HC with a skin, the skin is LIGP (laser processing parameters: laser power is 11 W, laser running speed is 635 mm / s, PPI = 500, and DL = 3 mm).

[0126] To avoid the interference and detection of radar, the EMI shielding and stealth performance is shown in ​ . The application of Sandwich HC in electromagnetic shielding, ​ , shows that the average SE Total (37.6 dB) exceeds the commercial standard of EMI shielding materials (20 dB) (reference: Y. Qu, X. Li, X. Wang, H. Dai, Compos. Sci. Technol. 2022, 230, 109753). The application of 3D LIG-HC in stealth, ​ , confirms that the entire RL value of the X-band is lower than -10 dB, which indicates that the smart honeycomb structure material can absorb more than 90% of electromagnetic waves (reference: B. Zhao, Z. Yan, Y. Du, L. Rao, G. Chen, Y. Wu, L. Yang, J. Zhang, L. Wu, D. W. Zhang, R. Che, Adv. Mater. 2023, 35, 2210243).

[0127] From the above examples, the present application has at least the following advantages:

[0128] 1. Preparation method level

[0129] (1) The present application uses laser-induced technology combined with honeycomb manufacturing technology to realize the preparation of laser-induced graphene smart honeycomb structure material (3DLIG-HC). This method eliminates the technical obstacles of traditional honeycomb manufacturing technology applied to LIGP honeycomb manufacturing, does not need additional process to give it intelligence, is simple to operate, low in cost, high in efficiency and mild in preparation environment. Compared with the construction of traditional smart honeycomb, the laser-induced graphene smart honeycomb structure material proposed by the present application uses LIGP as the honeycomb framework and thermoplastic polymer film structure as the bonding layer, without the need for post-processing steps such as impregnation / pasting, realizing the in-situ integrated manufacturing of smart honeycomb. (2) The present application can easily realize the flexible manufacturing of laser-induced graphene smart honeycomb structure material through the pre-design of the forming structure, including the expandable macro size, the adjustable edge length of the honeycomb structure, the designability of the graphene cluster structure, and the selective attachment of the skin structure. The pre-design principle is shown in Examples 3-4. Specifically, the large size and adjustable stacking number of LIGP determined by the open laser printing platform realize the large size preparation of the macro size of 3D LIG-HC; by customizing the shape of LIGP and thermoplastic polymer film (such as TPU film) through computer software, the 3D LIG-HC internal honeycomb structure with different edge lengths can be realized; by controlling the stretching expansion degree, the 3D LIG-HC internal honeycomb structure with different shapes can be realized; by selectively attaching different types of skin structure, various types of smart sandwich honeycomb structure materials can be obtained. (3) By adjusting the processing parameters, the present application optimizes the processing technology to realize the strengthening of the bonding between the honeycomb structure interfaces, and realizes the multifunctional characteristics of the honeycomb structure. Specifically, by adjusting the laser-induced parameters and hot-pressing parameters, the penetration of the thermoplastic polymer film bonding layer between the LIGP layers is optimized to improve the bonding strength between the interfaces, realizing the preparation of high-strength honeycomb structure; by adjusting the concentration of the resin material, the smart honeycomb structure with light weight, anisotropic electric / power / sensing characteristics, energy absorption characteristics, electromagnetic shielding / absorption characteristics is realized.

[0130] 2. Product level

[0131] (1) The product size is controllable, the shape is various, and it has the characteristics of light weight, high deformation tolerance, load bearing, etc. The diversified structure and characteristic display is shown in Examples 5-7. (2) The product performance is controllable and has multifunctional characteristics, as shown in Examples 8-9. (3) The product application scenarios are wide, such as the product with flame retardant characteristics, which can also be used for electric heating, ice prevention, ice removal, high temperature warning, vibration monitoring, heavy object detection, electromagnetic shielding, and stealth.

[0132] 3. Application level

[0133] (1) 3D LIG-HC can be constructed into an intelligent wing structure for ice prevention and de-icing. As shown in the results of Example 10, 3D LIG-HC has an electric heating property and can be used as a heater. On the one hand, low-voltage heating prevents icing on the surface of the wing. On the other hand, when the wing surface is iced, high-voltage rapid de-icing is achieved. (2) 3D LIG-HC can be used for temperature warning. As shown in the results of Example 11, the resistance of 3D LIG-HC has a negative temperature coefficient. With the change of the ambient temperature, the resistance of 3D LIG-HC changes instantaneously and correspondingly. In particular, it has a sensitive detection capability for high temperature. (3) 3D LIG-HC can be used for fire retardation. As shown in the results of Example 12, compared with pure resin plates or pure PI honeycomb structures, 3D LIG-HC has a certain fire retardation property due to the presence of graphene particles, which can quickly disperse and transfer heat. (4) 3D LIG-HC can be used for array sensing. As shown in the results of Example 13, 3D LIG-HC has excellent strain sensing sensitivity and can be constructed into an array sensor to detect the weight distribution of a scissors. (5) 3D LIG-HC can be used for detecting the loading of static load. As shown in the results of Example 14, 3D LIG-HC has excellent strain sensing sensitivity and can be used as a sensor to sensitively detect the loading of different positions and different weights. (6) 3D LIG-HC can be used for detecting vibrations of different frequencies. As shown in the results of Example 15, 3D LIG-HC has excellent strain sensing sensitivity and can be used as a sensor to sensitively detect vibrations of different frequencies. (7) 3D LIG-HC can be used for electromagnetic wave shielding and stealth. As shown in the results of Example 16, 3D LIG-HC has excellent electrical conductivity and can reflect and absorb electromagnetic waves well, thereby achieving electromagnetic shielding and stealth.

[0134] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for preparing a laser-induced graphene smart honeycomb structure material, comprising the following steps: laser-induced double-sided polyimide substrate to obtain a laser-induced graphene substrate; the laser-induced graphene substrate comprises a first graphene layer, a polyimide layer and a second graphene layer arranged in a stack; at least two layers of the laser-induced graphene substrate and a plurality of thermoplastic core strip glues are assembled and sequentially subjected to hot pressing, stretching, glue dipping and curing to obtain the laser-induced graphene smart honeycomb structure material; wherein a plurality of the thermoplastic core strip glues are arranged in parallel between the adjacent two layers of the laser-induced graphene substrate.

2. The production method according to claim 1, characterized by, When the number of layers of the laser-induced graphene substrate in the laser-induced graphene smart honeycomb structure material is ≥ 3, the projection area of the thermoplastic core strip glue on the upper surface and the lower surface of the laser-induced graphene substrate at a non-surface position in the laser-induced graphene smart honeycomb structure material does not overlap.

3. The production method according to claim 1 or 2, characterized by, The thermoplastic core strip glue is obtained by cutting a thermoplastic film, and the thermoplastic film comprises one or more of thermoplastic polyurethane film, polyethylene film, polypropylene film, polyvinyl chloride film, polystyrene film and polyester film; the thickness of the thermoplastic film is 10-100 μm.

4. The production method according to claim 1, characterized by, The polyimide substrate comprises one or more of polyimide paper, polyimide felt, polyimide film and polyimide cloth; the thickness of each layer of the polyimide substrate is 10-200 μm.

5. The production method according to claim 1 or 4, characterized by, The conditions of the laser induction include: laser power ≤ 25 W, laser running speed ≤ 1270 mm / s, pixels per inch ≤ 1000, and defocusing distance ≤ 4 mm; the thickness of the polyimide layer in each layer of the laser-induced graphene substrate is independently 20-90 μm.

6. The method of claim 1, wherein, The conditions of the hot pressing include: temperature 80-200 ℃, pressure 1-10 MPa, and holding time 1-1000 min.

7. The preparation method according to claim 1, characterized in that, The resin material used for the glue dipping is a thermosetting resin, and the thermosetting resin comprises one or more of epoxy resin, polyester resin, phenolic resin, melamine formaldehyde resin, furan resin, polybutadiene resin and silicone resin. 8.A laser-induced graphene smart honeycomb structure material prepared by the method of any one of claims 1-7. 9.A smart sandwich honeycomb structure material comprising the laser-induced graphene smart honeycomb structure material of claim 8 and a skin arranged on the upper surface and the lower surface of the laser-induced graphene smart honeycomb structure material. 10.Use of the laser-induced graphene smart honeycomb structure material of claim 8 or the smart sandwich honeycomb structure material of claim 9 in the fields of electric heating, anti-icing, deicing, high-temperature warning, flame retardation, pressure sensing, vibration monitoring, electromagnetic shielding and stealth.

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