High-thermal-conductivity insulating composite material based on MXene and amino-modified cellulose and preparation method of high-thermal-conductivity insulating composite material

Abstract

The invention discloses a high thermal conductivity insulating composite material based on MXene and amino modified cellulose and a preparation method thereof, amino modified cellulose (ABC) and MXene (Ti3C2Tx) are introduced into a traditional particle filling epoxy resin system, and a particle-fiber-nanosheet synergistic enhancement and synergistic heat conduction composite structure is constructed, so that the thermal conductivity of the composite material is improved, and the thermal conductivity of the composite material is improved. Therefore, excellent mechanical property, high thermal conductivity and stable insulating property are realized. According to the composite material, the heat-conducting property can be remarkably improved while the excellent electrical insulating property is maintained, and the composite material is widely applied to the fields of high-voltage electrical equipment, aerospace, new energy automobiles and the like and is particularly suitable for high-performance composite materials needing to have the heat conductivity and the insulating property at the same time.

Description

Technical Field

[0001] This invention belongs to the field of high thermal conductivity insulating composite materials, specifically relating to a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose and its preparation method. Background Technology

[0002] Traditional polymer insulating materials (such as pure epoxy resin) are not only electrical insulators but also poor thermal conductors. Their inherently low thermal conductivity (typically <0.3 W / m·K) easily leads to heat accumulation during device operation, causing localized overheating, aging, and safety hazards. Current improvement methods, primarily using high-proportion filling with insulating particles such as aluminum nitride, can improve thermal conductivity to some extent, but inevitably lead to severe degradation of the material's mechanical properties, manifesting as significant brittleness, insufficient toughness and strength, and inability to meet the load-bearing requirements of structural components. Therefore, existing technologies have consistently struggled to produce a comprehensive material that simultaneously achieves excellent electrical insulation, efficient thermal conductivity, and superior mechanical properties. This invention provides a composite material that overcomes the aforementioned technical challenges through the synergistic effect of MXene and amino-modified cellulose, meeting the requirement of both high thermal conductivity and high insulation while effectively improving the material's mechanical properties. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose, and a method for preparing the same. This composite material maintains excellent electrical insulation properties while significantly improving thermal conductivity, making it widely applicable in high-voltage electrical equipment, aerospace, new energy vehicles, and other fields. It is particularly suitable for high-performance composite materials requiring both thermal conductivity and insulation.

[0004] This invention provides a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose, and its preparation method. Its core innovation lies in introducing amino-modified cellulose (ABC) and MXene (Ti3C2T) into a traditional particulate-filled epoxy resin system. x By constructing a composite structure of "particle-fiber-nanosheet" synergistic reinforcement and synergistic thermal conduction, excellent mechanical properties, high thermal conductivity and stable insulation properties are achieved.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose, the process is as follows: 1) Preheat the epoxy resin at 65~75℃ for 20~40 minutes; add the surface-treated insulating substrate particles and the surface-treated insulating thermally conductive particles to the epoxy resin, and mix at a constant temperature of 65~75℃ for 5~20 minutes under normal pressure and a stirring speed of 300~500 rpm, and then continue stirring at a vacuum degree ≤-0.095 MPa and 400~600 rpm for 10~30 minutes. 2) Under conditions of 65~75℃ and vacuum degree ≤-0.095 MPa, add the surface-modified chopped glass fibers to the mixture in step 1) and stir at 100~300 rpm for 10~20 minutes; 3) Raise the temperature of the material in 2) to 90~110℃, add curing agent, accelerator, defoamer and amino-modified cellulose / Ti3C2 composite material to the system, and stir at 200~400 rpm under the conditions of 90~110℃ and vacuum degree ≤-0.095 MPa until it is visually confirmed that the curing agent has been completely dissolved and all components are mixed evenly. 4) After thoroughly cleaning the metal mold, evenly spray a layer of release agent onto the surface of its cavity. Then, preheat the mold at 90~110℃ for 20~40 minutes. Use a glass rod preheated to 70~90℃ to guide the flow and inject the composite slurry from step 3) along the mold's pouring port. Degas the slurry in the mold under a vacuum of -0.05 MPa ~ -0.1 MPa. 5) After degassing, immediately transfer the mold to an oven preheated to 85~95℃ for three-stage curing: First stage, heat to 95~105℃ at a rate of 1.5~2.5℃ / min and cure at a constant temperature for 100~150 minutes; Second stage, heat to 120~140℃ at a rate of 1~2℃ / min and cure at a constant temperature for 100~150 minutes; Third stage, heat to a final temperature of 170~190℃ at a rate of 0.8~1.2℃ / min and cure at a constant temperature for 150~200 minutes. 6) After the curing process is complete, let the mold cool naturally in the oven. When the temperature drops below 60℃, remove the mold to obtain the product.

[0006] Further, in step 1), the surface-treated insulating substrate particles refer to alumina particles or silica particles treated with a silane coupling agent, and the surface-treated insulating thermally conductive particles refer to aluminum nitride particles or boron nitride particles treated with a silane coupling agent. The specific preparation process of the surface-treated insulating substrate particles and the surface-treated insulating thermally conductive particles is as follows: the insulating substrate particles or insulating thermally conductive particles are added to a silane coupling agent solution and stirred at 50~70℃ for 100~150 minutes; the silane coupling agent is at least one of KH540, KH550, KH560, KH561, KH-792, GLYMO, A-187, A-189, A-1100 and A-1120, the amount of silane coupling agent added is 1~2% of the mass of the insulating substrate particles or insulating thermally conductive particles, the amount of surface-treated insulating substrate particles added is 1%~3% of the mass of the epoxy resin, and the amount of surface-treated insulating thermally conductive particles added is 1~30% of the mass of the epoxy resin. Both the insulating substrate particles and the insulating thermally conductive particles have a particle size of 10 nm to 10 μm. Before being added to the silane coupling agent solution, the insulating substrate particles and insulating thermally conductive particles need to be dried at 110–130 °C for 1–3 hours. The surface-treated insulating thermally conductive particles are used to construct the basic thermal conduction pathways and ensure insulation performance.

[0007] Furthermore, in step 3), the preparation process of the amino-modified cellulose / Ti3C2 composite material is as follows: S1. Dopamine was added to the Tris-HCl buffer solution of fiber dispersion and stirred at 20-30°C for 20-30 hours. After centrifugation and washing with water, polydopamine-coated cellulose was obtained. The polydopamine-coated cellulose was dispersed in a polyethyleneimine solution and stirred at 45-55°C for 10-15 hours. After centrifugation and washing with water, amino-modified cellulose was obtained (its amino-modifying groups can form a reinforced interfacial bond with epoxy resin and MXene, improving mechanical properties and thermal conductivity, while ensuring excellent electrical insulation). S2. Disperse amino-modified cellulose in water, add Ti3C2 (to enhance the thermal conductivity of the composite material and work synergistically with cellulose and thermally conductive particles to construct an efficient three-dimensional thermally conductive network), sonicate at room temperature for 20-40 minutes, stir for 1-3 hours, and freeze-dry to obtain the final product.

[0008] Furthermore, the mass ratio of cellulose, dopamine, and polyethyleneimine is 1:1:1, the concentration of Tris-HCl buffer is 5-15 mM, the pH is 8-9, and the concentration of polyethyleneimine solution is 4-6 mg / mL.

[0009] Further, in step 2), the preparation process of the surface-modified chopped glass fibers is as follows: The chopped glass fibers are added to a silane coupling agent solution and stirred at 50-70°C for 80-100 minutes. Through hydrolysis-condensation reaction, the coupling agent molecules are firmly grafted onto the fiber surface, thereby endowing it with reactive epoxy groups. The silane coupling agent is at least one of KH540, KH550, KH560, KH561, KH-792, GLYMO, A-187, A-189, A-1100, and A-1120. The amount of silane coupling agent added is 1-3% of the solvent mass in the silane coupling agent solution, and the amount of surface-modified chopped glass fibers added is 1%-3% of the epoxy resin mass. The length of the chopped glass fibers is 1-10 mm, and they need to be dried at 100-110°C for 0.5-1.5 hours before being added to the silane coupling agent solution. Its key feature is that the fiber surface is modified with a silane coupling agent, carrying epoxy groups that can react with epoxy resin.

[0010] Further, in step 1), the epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenolic epoxy resin, alicyclic epoxy resin, epoxy phenolic resin, and multifunctional epoxy resin. It serves as both the continuous phase and the binder phase of the composite material. Preferably, the epoxy resin is at least one of E-51, E-44, E-51F, EPON1001, EPON 1004, PRM-550, Tactix 742, Araldite LY 1564, EP-ON 811, Araldite GY 258, Epon 828, CYDF-170, and F-51.

[0011] Further, in step 3), the curing agent is at least one of 4,4'-diaminodiphenyl sulfone (DDS), 4,4'-diaminodiphenylmethane (DDM), methylhexahydrophthalic anhydride (MeHHPA), and methylnadic anhydride (MNA), used to crosslink and cure the system at high temperature, and the amount added is 30% to 40% of the epoxy resin mass; the accelerator is at least one of tris(dimethylaminomethyl)phenol, 2-ethyl-4-methylimidazolium, and triethylenediamine, and the amount added is 0.5% to 2% of the epoxy resin mass; the defoamer is one of silicone-based defoamer, polyether defoamer, and fatty alcohol defoamer, and the amount added is 0.1% to 0.5% of the epoxy resin mass.

[0012] Preferably, the accelerator is at least one of DMP-30, DMP-23, EMI-24 and triethylenediamine, and the defoamer is at least one of BYK-A 530, BYK-022, TEGOAir 910, FOAMASTER 12 and AEROSIL 200.

[0013] Furthermore, the preparation process of the silane coupling agent solution is as follows: anhydrous ethanol and deionized water are mixed in a volume ratio of (9~10):1 to obtain a mixed solvent. The pH value of the mixed solvent is adjusted to 4~5 with glacial acetic acid. The silane coupling agent is added to the pH-adjusted mixed solvent and stirred for 20~40 minutes to obtain the silane coupling agent solution.

[0014] The above preparation method yields a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose.

[0015] The surface modification of MXene (Ti3C2Tx) in this invention involves chemically treating the MXene surface to remove impurities and make it easier to combine with other components. MXene can form a good interfacial bond with cellulose and resin matrices, improving the thermal conductivity and mechanical strength of the composite material.

[0016] Preparation of amino-modified cellulose: After amino modification, cellulose is endowed with reactive amino groups, which enhances its chemical bonding force with the resin matrix and improves its mechanical properties. Cellulose plays a role in materials not only in enhancing mechanical strength but also in improving toughness and thermal conductivity.

[0017] The present invention has the following beneficial effects: This invention achieves breakthrough improvements in thermal conductivity, mechanical properties, and insulation properties by introducing a synergistic reinforcement system formed by amino-modified cellulose (ABC) and MXene (Ti3C2Tx) with chopped glass fibers and highly thermally conductive insulating particles (such as aluminum nitride and boron nitride). Its core mechanism lies in: 1. Constructing an efficient three-dimensional collaborative heat conduction network: In traditional single-particle filled systems, thermally conductive particles are typically randomly distributed within the resin matrix, separated by resin with low thermal conductivity, forming numerous "thermal barriers." Effective bridging between particles is difficult, resulting in a tortuous and discontinuous heat transfer path. The short-cut glass fibers introduced in this invention (with a thermal conductivity of approximately 1.2 W / m·K) not only serve as secondary heat conduction pathways but also, through their interwoven structure within the composite material, act as "thermal bridges" connecting isolated clusters of thermally conductive particles. This successfully links the previously isolated particle "heat islands," constructing a three-dimensional continuous thermally conductive network composed of an interwoven and interconnected "fiber backbone network" and "particle filling network."

[0018] 2. The thermal conductivity enhancement effect of MXene: By introducing MXene (Ti3C2Tx), a two-dimensional material with excellent thermal conductivity, the thermal conductivity network of the composite material can be further enhanced. MXene, as a thermal channel, provides a highly efficient heat transfer path, enhancing the thermal conductivity of the entire composite system. Through synergistic effects with amino-modified cellulose (ABC) and chopped glass fibers, MXene effectively improves the overall thermal management capability of the composite material.

[0019] Ti3C2Tx is a two-dimensional material with unique surface functionalization. Its distinctive feature lies in the chemical etching process used to remove the aluminum layer from Ti3AlC2, exposing the Ti3C2 layer and introducing functional groups containing hydroxyl (-OH), fluorine (-F), and oxygen (-O) groups onto its surface. These surface groups are collectively referred to as Tx. These functional groups endow Ti3C2Tx with excellent hydrophilicity and chemical reactivity, and can improve its interfacial bonding with other materials, making it promising for broad applications in electrochemistry, catalysis, and adsorption. In the preparation of Ti3C2TxMXene nanosheets, a strongly acidic solution is first generated by mixing 9 M concentrations of hydrogen chloride (HCl) and lithium fluoride (LiF). Then, Ti3AlC2 powder is slowly added to the solution, and the mixture is stirred at 42°C for 48 hours to carry out a chemical etching reaction. During this reaction, the aluminum layer is removed, exposing the Ti3C2 layer, and functional groups such as -OH, -F, and -O (i.e., Tx) are introduced onto its surface. These functional groups not only endow Ti3C2 with strong hydrophilicity and chemical reactivity, but also improve its interfacial bonding ability with resin matrices or other materials. After the etching reaction is completed, the suspension is centrifuged and sonicated to remove excess chemical reactants, ensuring that the Tx groups are uniformly distributed on the surface of the Ti3C2 nanosheets, ultimately obtaining stable and uniform Ti3C2Tx nanosheets. This process enhances the surface activity of Ti3C2 nanosheets, further improving their application potential in catalysis, electrochemistry, and composite materials.

[0020] 3. Significant reduction in interfacial thermal resistance: The introduction of cellulose and MXene successfully reduced the interfacial thermal resistance, providing a continuous and efficient energy transfer path for phonons (the main heat carriers), thereby significantly improving the thermal conductivity of the composite material while ensuring electrical insulation. This structure ensures excellent thermal conductivity and maintains electrical insulation properties, successfully resolving the contradiction between thermal conductivity and insulation in traditional materials.

[0021] 4. Enhanced mechanical properties: The cellulose network in this invention not only provides thermal conductivity but also significantly enhances the mechanical strength and toughness of the composite material, particularly in terms of flexural strength, tensile strength, and impact resistance. The synergistic effect of MXene and amino-modified cellulose not only improves the structural stability of the material but also effectively enhances its fatigue durability. This structural design solves the problem of deteriorated mechanical properties often faced by highly filled insulating composite materials while improving thermal conductivity.

[0022] The composite material prepared in this invention achieves a balance and optimization of thermal conductivity, mechanical properties, and insulation properties through a rationally designed "particle-fiber-nanosheet" synergistic reinforcement structure. This novel composite material system provides an ideal material solution for various industrial applications, particularly suitable for high-voltage electrical equipment, aerospace, and new energy vehicles, and is of great significance for improving the safety and stability of such equipment.

[0023] In summary, by introducing MXene and amino-modified cellulose, this invention successfully constructs a highly efficient three-dimensional thermally conductive network. This significantly improves the thermal conductivity of the composite material while maintaining electrical insulation, and also substantially enhances its mechanical properties, overcoming the limitations of traditional materials that struggle to balance thermal conductivity and mechanical performance. This composite material has broad application prospects and is particularly suitable for applications requiring high thermal conductivity and high insulation. Attached Figure Description

[0024] Figure 1 This is a physical image of sample 3 in Table 5 of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited thereto.

[0026] 1. Preparation of surface-modified glass fibers 1) Preparation of silane hydrolysis solution: Accurately measure 450 mL of anhydrous ethanol and 50 mL of deionized water to prepare 500 mL of a mixed solvent with a volume ratio of 9:1. Adjust the pH of the mixed solvent to 4.5 using glacial acetic acid. Then, add 2% (by mass) of silane coupling agent KH-560 to the solution. Place the mixture on a magnetic stirrer and stir continuously at 500 rpm at room temperature for 30 minutes to ensure complete hydrolysis of the silane coupling agent.

[0027] 2) Fiber impregnation and reaction: 50 grams of short glass fibers (3 mm in length) that have been pre-dried at 110°C for 1 hour are completely immersed in the prepared hydrolysate. The entire system is placed in a constant temperature water bath at 60°C and mechanically stirred at 200 rpm for 90 minutes to ensure that the fiber surface and the hydrolyzed silane complete a full condensation reaction.

[0028] 3) Cleaning and Drying: After the reaction, the fibers were separated by vacuum filtration using a Buchner funnel. Subsequently, the fibers were rinsed three times with 300 mL of anhydrous ethanol to thoroughly remove the physically adsorbed coupling agent. The washed fibers were then spread evenly in a petri dish and dried in a 105°C oven for 120 minutes. Finally, the fibers were transferred to a vacuum drying oven at 80°C for 60 minutes, and then stored in a desiccator for later use.

[0029] 2. Preparation of surface-treated particulate fillers 1) Preparation of silane hydrolysis solution: Accurately measure 500 mL of anhydrous ethanol and 50 mL of deionized water to prepare a mixed solvent with a volume ratio of 10:1. Adjust the pH of the mixed solvent to 4.5 using glacial acetic acid. Then, add 1.5% (by weight of the alumina particles to be treated) of silane coupling agent KH-560 to the solution. Place the mixed solution on a magnetic stirrer and stir continuously at 500 rpm at room temperature for 30 minutes to ensure complete hydrolysis of the silane coupling agent.

[0030] 2) Particle impregnation and reaction: 200 g of spherical alumina particles (5 μm in diameter) that have been pre-dried under vacuum at 120°C for 2 hours are slowly added to the prepared hydrolysate. The entire system is placed in a constant temperature water bath at 60°C and mechanically stirred at 400 rpm for 120 minutes to ensure that the aluminum nitride particles and the hydrolyzed silane undergo a complete condensation reaction.

[0031] 3) Cleaning and Drying: After the reaction was complete, the alumina particles were separated by suction filtration using a Buchner funnel. The filter cake was then rinsed three times with 600 mL of anhydrous ethanol. The cleaned alumina particles were spread evenly in a petri dish and dried in a 100°C oven for 180 minutes. Finally, the particles were transferred to a vacuum oven at 80°C and kept for 120 minutes. After drying, they were placed in a desiccator for later use.

[0032] 4) For the surface treatment of other high thermal conductivity insulating particles such as aluminum nitride (0.5μm particle size) and boron nitride (2μm particle size), refer to the above steps.

[0033] 3. Preparation of amino-modified cellulose / Ti3C2 composite material (ABC / MX) 1) Preparation of Ti3C2Tx MXene nanosheets Ti3C2Tx MXene nanosheets were prepared by a chemical etching method, with the following steps: First, 20 mL of 9 M hydrogen chloride (HCl) and 1 g of lithium fluoride (LiF) were stirred in a Teflon container for 5 minutes. Then, 1 g of Ti3AlC2 powder was slowly added to the solution, and the mixture was stirred at 42°C for 48 hours. After the etching reaction was complete, the suspension was washed with deionized water at 3500 rpm until the pH reached neutral. Next, the precipitate was collected, and 40–50 mL of water was added for sonication for 2 hours, followed by centrifugation at 6000 rpm for 10 minutes. The supernatant (15–30 mL) was collected, containing approximately 0.5 g of the treated Ti3C2Tx MXene nanosheets.

[0034] 2) Preparation of ABC / MX composite material The specific preparation steps of amino-modified cellulose are as follows: First, 1 gram of cellulose (BC) was dispersed in 200 mL of Tris-HCl buffer solution (pH = 8.5, 10 mM). Then, 1 gram of dopamine (DA) was added under ultrasonic conditions, and the mixture was continuously stirred at 800 rpm for 24 hours at 26 °C to obtain polydopamine (PDA)-coated cellulose (PDA-BC). Next, PDA-BC was thoroughly washed with deionized water to remove surface-unstable PDA. Then, PDA-BC was dispersed in 200 mL of polyethyleneimine (PEI) solution (concentration 5 mg / mL) and stirred at 323 K for 12 hours. The resulting reddish-brown precipitate was washed repeatedly with deionized water to remove unreacted PEI, and finally dispersed in deionized water to obtain an amino-modified cellulose (ABC) dispersion with a concentration of 10 mg / mL.

[0035] In the experiment, an electrostatic self-assembly strategy was employed to prepare amino-modified cellulose / Ti3C2 composites (ABC / MX). During preparation, the volume of the Ti3C2Tx suspension ranged from 15 mL to 30 mL, containing approximately 0.5 g of Ti3C2 nanosheets, depending on the desired final Ti3C2 mass. The volume of the ABC dispersion was 200 mL, containing 1 g of cellulose (BC). The mass ratio of cellulose to Ti3C2 was controlled by adjusting the volumes of the two solutions to achieve different mass ratios. Specifically, the mass ratio of ABC to MX was varied from 5:1 to 1:5 to test the performance of the composites at different mass ratios. The mixed solutions were ultrasonically treated at room temperature for 30 minutes, followed by stirring for 2 hours. This adjustment allowed for precise control of the cellulose to Ti3C2 ratio in the composites, thereby optimizing the thermal conductivity, mechanical properties, and insulation properties of the composites. Finally, after 12 hours of freeze-drying, the resulting composite material formed an amino-modified cellulose / Ti3C2 composite material (ABC / MX), which was compared with pure cellulose (BC) and cellulose / Ti3C2 composite material (BC / MX, mass ratio 2:1).

[0036] 4. Resin preparation and filler introduction 1) Matrix preheating: Accurately weigh 100 grams of bisphenol A epoxy resin (model E-51) and pour it into a 250 ml wide-mouth beaker. Then place the beaker in a forced-air drying oven preheated to 70°C for 30 minutes. This process aims to effectively reduce the initial viscosity of the resin system and create favorable conditions for the uniform dispersion of fillers.

[0037] 2) Dispersion of particulate fillers: Transfer the preheated epoxy resin beaker to the heating plate of a magnetic stirrer, which is also preheated to 70°C. Then, weigh and mix the surface-treated aluminum nitride particles and surface-treated insulating and thermally conductive particles according to the mixing ratio, dividing them into three equal batches, and slowly add them to the epoxy resin sequentially. Under a constant temperature of 70°C, first mix for 10 minutes at atmospheric pressure and a stirring speed of 400 rpm to initially wet the filler. Then, turn on the vacuum system and, under a vacuum of -0.095 MPa, increase the stirring speed to 500 rpm and continue stirring for 20 minutes. This operation aims to completely remove any trapped gas from the mixture and ensure that the aluminum nitride particles achieve a highly uniform dispersion in the resin matrix.

[0038] 3) Addition of surface-modified fibers: Under the conditions of maintaining a system temperature of 70℃ and a vacuum of -0.095 MPa, the prepared surface-modified chopped glass fibers are slowly and evenly sprinkled into the mixture. To prevent mechanical damage and breakage of the fibers caused by high-speed stirring, the stirring speed should be immediately reduced to 200 rpm, and stirring should continue for 15 minutes under these mild conditions to ensure that the fibers are evenly distributed in the system and that their length remains intact.

[0039] 4) Addition of curing agent, ABC / MX, accelerator, and defoamer: After fiber dispersion, raise the temperature of the entire mixing system to 100℃. Then, add precisely weighed 4,4'-diaminodiphenyl sulfone (DDS, 35 g) curing agent, ABC / MX, defoamer (BYK-022, 0.2% of epoxy resin mass), and accelerator (DMP30, 1% of epoxy resin mass) to the system. Stir at a low speed of 300 rpm for 15 minutes at 100℃ and a vacuum of -0.095 MPa until visually confirmed that the DDS curing agent is completely dissolved and all components are uniformly mixed, ultimately forming an epoxy resin composite slurry with suitable viscosity suitable for casting.

[0040] 5) In the preparation process of this invention, accelerators and defoamers are added to optimize the curing process of the composite material and improve its processing performance. Commonly used accelerators include dimethylaniline (DMA), such as DMP-30 (Invista), which can increase the curing reaction rate and reduce the curing time. It is suitable for most epoxy resin curing systems and is usually added at 0.5%-2% of the resin matrix; 4,4'-dimethyldiphenylamine (DMP-23), such as DMP-23 (Huntsman), is used to accelerate the reaction between epoxy resin and amine curing agents and is widely used in high-performance epoxy resin systems. It is added at 0.5%-1% of the resin matrix; In addition, triethylenediamine (TETA), such as TETA (Huntsman), is often used as a curing accelerator, especially in low-temperature curing systems, where it can improve curing efficiency. It is usually added at 0.5%-1% of the resin matrix. As for defoamers, commonly used ones include silicone-based defoamers, such as BYK-022 (BYK Additives), which effectively removes bubbles during the mixing process of epoxy resin and curing agent, especially in systems with high filler content. The typical addition amount is 0.1%-0.5% of the resin matrix. Polyether-based defoamers, such as FOAMASTER 12 (Evonik), are suitable for defoaming epoxy resins, effectively inhibiting bubble formation and ensuring material uniformity and surface quality. The addition amount is 0.1%-0.3% of the resin matrix. Fatty alcohol-based defoamers, such as AEROSIL 200 (Evonik), also effectively remove bubbles without negatively impacting other material properties. The typical addition amount is 0.1%-0.3% of the resin matrix. The addition of these accelerators and defoamers can significantly improve the preparation efficiency of composite materials and the quality of the final product.

[0041] 5. Pouring and Curing 1) After thoroughly cleaning the metal mold, evenly spray a thin layer of fluorinated mold release agent onto the surface of its cavity. Then place the mold in a forced-air oven and preheat it at 100°C for 30 minutes. Use a glass rod preheated to 80°C to guide the flow, and slowly and continuously inject the composite slurry prepared in step 2 along one side of the mold's pouring gate. The entire pouring process must be completed within 3 minutes. Immediately after completion, use a preheated stainless steel scraper to clean the residual material at the pouring gate.

[0042] 2) After pouring, quickly transfer the entire mold to a vacuum drying oven and perform a step-by-step degassing procedure. First, maintain a low vacuum of -0.05 MPa for 2 minutes to allow large air bubbles inside the slurry to escape smoothly. Then, gradually increase the vacuum to -0.1 MPa over 1 minute and maintain this state for 8 minutes to completely eliminate micron-sized air bubbles that are difficult to escape. This degassing stage takes a total of 15 minutes.

[0043] 3) After degassing, immediately transfer the mold to a preheated 90°C forced-air oven and strictly adhere to the three-stage curing procedure. In the first stage, heat to 100°C at a rate of 2°C / min and maintain this temperature for 120 minutes to allow the system to initially crosslink and gel. In the second stage, heat to 130°C at a rate of 1.5°C / min and maintain this temperature for 120 minutes to develop and solidify the network. In the third stage, heat to a final temperature of 180°C at a rate of 1°C / min and perform post-curing at this temperature for 180 minutes to ensure complete crosslinking and optimal heat resistance and mechanical properties of the material.

[0044] 4) After all curing processes are complete, turn off the oven power and allow the mold to cool naturally inside the oven. Forced rapid cooling is strictly prohibited. The mold can only be removed when the oven temperature drops below 60℃. Finally, using a copper or wooden demolding tool, carefully remove the cured composite material sample or strip from the cavity to obtain the final product. Allow it to cool to room temperature before performance testing.

[0045] 6. Performance Testing and Characterization 1) Insulation performance characterization Dielectric breakdown strength testing was conducted according to GB / T 1408. The sample was a 10cm x 10cm epoxy composite plate with a thickness of 0.5 mm. Surface imperfections were removed by light polishing with sandpaper, and the sample was dried in an oven at 80 ℃ for 12 h to eliminate moisture absorption. An oil-immersed electrode system was used, with upper and lower electrodes being 25mm diameter ball-plate or ball-ball electrodes. The sample was fully immersed in transformer oil and allowed to stand for 10 min to remove air bubbles before voltage was increased. The voltage was applied at a linear rate of 1 kV / s until instantaneous breakdown occurred, and the instrument recorded the breakdown voltage (kV). The breakdown strength was obtained by dividing the breakdown voltage by the sample thickness (kV / mm). Each test group was measured at least 5-8 times, and the average value after removing outliers was taken as the final breakdown strength of the material.

[0046] Dielectric constant and dielectric loss were measured according to GB / T 1409 using a dielectric spectrometer or a precision impedance analyzer (Keysight 4294A). Composite material flat sheets with a diameter of approximately 50 mm and a thickness of approximately 1 mm were prepared, and both sides were uniformly plated with gold as electrodes, or silver paste electrodes with a diameter of 25 mm were used. The electrode layers were cured by drying at 120 ℃ for 30 min. Before testing, the samples were placed in an environment of 23 ± 2 ℃ and 50 ± 5% RH for 24 h. The samples were clamped in a parallel plate capacitor fixture, and the empty fixture capacitance was eliminated through automatic calibration. The test frequency was scanned from 100 Hz to 1 MHz, and the instrument automatically recorded the dielectric constant εr and dielectric loss tanδ as a function of frequency. The performance of conventional insulating materials was characterized by data at 1 kHz, and each group of samples was measured 3-5 times and the average value was taken.

[0047] 2) Characterization of mechanical properties The tensile properties of epoxy resin composites were tested according to GB / T 2567. Specimens were cured in appropriate molds and then conditioned for 24 hours at 23 ± 2 ℃ and 50 ± 5% relative humidity. During testing, the specimens were mounted in the clamps of an electronic universal testing machine (Instron or similar equipment), ensuring no stress concentration in the clamping area. Tensile tests were conducted at a constant displacement rate of 2 mm / min, and the load-displacement curves were recorded in real time. After specimen fracture, the instrument automatically calculated the maximum tensile stress and obtained the average tensile strength. At least 5 specimens were tested in each group to ensure the statistical reliability of the results.

[0048] 3) Characterization of thermal conductivity The thermal conductivity of epoxy resin composites shall be tested in accordance with GB / T 22588 (Flash method for measuring thermal diffusivity of materials) or ASTM E1461.

[0049] Thermal diffusivity test: The test was conducted using a laser flash thermal conductivity meter (such as Netzsch LFA 467 or Lindsay LFA 1000). A circular sample with a diameter of 12.7 mm and a thickness of 2.0 mm was prepared, ensuring both sides of the sample were flat and parallel. Before testing, the sample surface was uniformly carbon-sprayed or gold-plated to ensure sufficient absorption of the laser pulse and uniform emission of the infrared signal. The test was conducted at a constant temperature of 25°C. The instrument emitted short laser pulses to uniformly irradiate the lower surface of the sample, and an infrared detector recorded the temperature rise of the upper surface. By analyzing the temperature rise curve, the thermal diffusivity of the material (unit: mm² / s) was calculated using a mathematical model. Each sample was measured at least three times, and the average value was taken as the final result.

[0050] Thermal conductivity calculation: The thermal conductivity (λ, unit: W / (m·K)) of a material is calculated using the formula λ = α × Cp × ρ, based on the measured thermal diffusivity (α), the specific heat capacity (Cp), and the bulk density (ρ).

[0051] The specific heat capacity (Cp) can be tested using a differential scanning calorimeter (DSC) according to GB / T 19466.4, or directly measured by the specific heat capacity accessory of a laser flash thermal conductivity meter.

[0052] Bulk density (ρ) is calculated by accurately measuring the geometry and mass of the sample.

[0053] To comprehensively characterize the thermal management capabilities of materials, cross-validation can be performed simultaneously using a thermal constant analyzer (such as the Hot Disk TPS2200). This test uses a double-helix probe sensor, clamped between two flat samples (at least 30 mm × 30 mm in size). The test is conducted at room temperature, with the instrument applying a small, instantaneous heating power through the probe and simultaneously recording the temperature rise response, directly analyzing the material's thermal conductivity and thermal diffusivity.

[0054] The test results are detailed in Tables 1 to 4. In the following tables, the incorporation ratios of alumina, aluminum nitride, boron nitride, glass fiber, and cellulose / MXene are all based on the mass of epoxy resin. Alumina, aluminum nitride, and boron nitride refer to surface-treated alumina, aluminum nitride, and boron nitride, and glass fiber refers to surface-modified glass fiber.

[0055] Table 1. Formulation and properties of aluminum nitride as an insulating and thermally conductive particle composite material As shown in Table 1, with the same curing agent, epoxy resin and alumina, the material with the best performance is the aluminum nitride modified with silane coupling agent and the chopped glass fiber modified with silane coupling agent with an incorporation ratio of 2%.

[0056] Table 2. Formulation and properties of boron nitride as an insulating and thermally conductive particle composite material As shown in Table 2, with the same curing agent, epoxy resin and alumina, the material has the best performance when the boron nitride doping ratio modified by silane coupling agent is 20% and the chopped glass fiber doping ratio modified by silane coupling agent is 2%.

[0057] Table 3. Formulations and properties of composite materials with different proportions of cellulose / Ti3C2 containing aluminum nitride as insulating and thermally conductive particles and amino-modified cellulose. Table 3 shows that the weight ratio of ABC to MXene in the ABC / MX ratio significantly affects the insulation and thermal conductivity of the material. A higher ABC content results in stronger mechanical properties, while a higher MXene content leads to stronger thermal conductivity. In contrast, a 2:1 ABC to MXene ratio yields the most balanced performance, maintaining high insulation while leveraging the thermal conductivity of MX. Therefore, all subsequent ABC / MX materials used were prepared with a 2:1 ABC to MXene weight ratio.

[0058] Table 4. Formulations and properties of cellulose / Ti3C2 composites with aluminum nitride as insulating and thermally conductive particles and simultaneously incorporated with amino-modified materials. As shown in Table 4, when the incorporation ratio of silane coupling agent-modified aluminum nitride and silane coupling agent-modified chopped glass fiber is 2%, the incorporation ratio of amino-modified cellulose / Ti3C2 composite material is 4%, and the material performance is the best.

[0059] Table 5. Formulations and properties of cellulose / Ti3C2 composites with boron nitride as an insulating and thermally conductive particle and amino-modified. As shown in Table 5, when the silane coupling agent-modified boron nitride doping ratio is 20% and the silane coupling agent-modified chopped glass fiber doping ratio is 2%, the amino-modified cellulose / Ti3C2 composite material with a doping ratio of 4% exhibits the best performance.

[0060] Table 5 shows the actual sample 3. Figure 1 As shown, by Figure 1 As can be seen, the circular composite material sample prepared by the method of the present invention has a uniform surface. This material possesses both good formability and excellent insulation properties, fully demonstrating the advantages of the amino-modified MXene-reinforced high-performance insulating composite material and its preparation method provided by the present invention.

[0061] In addition to the above formulation, the epoxy resin matrix of the present invention may also be: bisphenol A type epoxy resin, such as E-51 (DER331, 628); bisphenol F type epoxy resin, such as CYDF-170; phenolic epoxy resin, such as F-51 (DEN431). The following types of curing agents are available: 4,4'-diaminodiphenyl sulfone (DDS); 4,4'-diaminodiphenylmethane (DDM); methylhexahydrophthalic anhydride (MeHHPA); methylnadic anhydride (MNA); Accelerators that can be selected include: tris(dimethylaminomethyl)phenol (DMP-30); 2-ethyl-4-methylimidazole (EMI-24), etc., added at 1%-5% together with the curing agent; Defoamers available: BYK-A series (e.g., BYK-A 530); EGO Air series (e.g., TEGO Air 910); Silane coupling agents available include: 3-glycidyl etheroxypropyltrimethoxysilane (KH-560, GLYMO, A-187); 3-glycidyl etheroxypropyltriethoxysilane (KH-561, A-189); 3-aminopropyltriethoxysilane (KH-550, A-1100); N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792, A-1120); and 3-aminopropyltrimethoxysilane.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the specific implementation of the present invention and not to limit it. Those skilled in the art should understand that any equivalent substitutions or obvious modifications made to the implementation of the present invention without changing its performance or use, without departing from the spirit of the present invention, should be covered within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose, characterized in that, The process is as follows: 1) Preheat the epoxy resin at 65~75℃ for 20~40 minutes; add the surface-treated insulating substrate particles and the surface-treated insulating thermally conductive particles to the epoxy resin, and mix at a constant temperature of 65~75℃ for 5~20 minutes under normal pressure and a stirring speed of 300~500 rpm, and then continue stirring at a vacuum degree ≤-0.095 MPa and 400~600 rpm for 10~30 minutes. 2) Under conditions of 65~75℃ and vacuum degree ≤-0.095 MPa, add the surface-modified chopped glass fibers to the mixture in step 1) and stir at 100~300 rpm for 10~20 minutes; 3) Raise the temperature of the material in 2) to 90~110℃, add curing agent, accelerator, defoamer and amino-modified cellulose / Ti3C2 composite material to the system, and stir at 200~400 rpm under the conditions of 90~110℃ and vacuum degree ≤-0.095 MPa until it is visually confirmed that the curing agent has been completely dissolved and all components are mixed evenly. 4) After thoroughly cleaning the metal mold, evenly spray a layer of release agent onto the surface of its cavity. Then, preheat the mold at 90~110℃ for 20~40 minutes. Use a glass rod preheated to 70~90℃ to guide the flow and inject the composite slurry from step 3) along the mold's pouring port. Degas the slurry in the mold under a vacuum of -0.05 MPa ~ -0.1 MPa. 5) After degassing, immediately transfer the mold to an oven preheated to 85~95℃ for three-stage curing; In the first stage, the temperature is increased to 95-105℃ at a rate of 1.5-2.5℃ / min and then kept at the temperature for 100-150 minutes to cure. In the second stage, the temperature is increased to 120-140℃ at a rate of 1-2℃ / min and kept at the temperature for 100-150 minutes to cure. In the third stage, the temperature is increased to the final 170-190℃ at a rate of 0.8-1.2℃ / min and kept at the temperature for 150-200 minutes to cure. 6) After the curing process is complete, let the mold cool naturally in the oven. When the temperature drops below 60℃, remove the mold to obtain the product.

2. The method for preparing the high thermal conductivity insulating composite material based on MXene and amino-modified cellulose according to claim 1, characterized in that, In step 1), the surface-treated insulating substrate particles refer to alumina particles or silica particles treated with a silane coupling agent, and the surface-treated insulating thermally conductive particles refer to aluminum nitride particles or boron nitride particles treated with a silane coupling agent. The specific preparation process of the surface-treated insulating substrate particles and the surface-treated insulating thermally conductive particles is as follows: the insulating substrate particles or insulating thermally conductive particles are added to a silane coupling agent solution and stirred at 50~70℃ for 100~150 minutes; the silane coupling agent is at least one of KH540, KH550, KH560, KH561, KH-792, GLYMO, A-187, A-189, A-1100 and A-1120, the amount of silane coupling agent added is 1~2% of the mass of the insulating substrate particles or insulating thermally conductive particles, the amount of surface-treated insulating substrate particles added is 1%~3% of the mass of epoxy resin, and the amount of surface-treated insulating thermally conductive particles added is 1~30% of the mass of epoxy resin.

3. The method for preparing a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose according to claim 1, characterized in that, In step 3), the preparation process of the amino-modified cellulose / Ti3C2 composite material is as follows: S1. Dopamine was added to the Tris-HCl buffer solution of fiber dispersion and stirred at 20-30°C for 20-30 hours. After centrifugation and washing with water, polydopamine-coated cellulose was obtained. The polydopamine-coated cellulose was dispersed in polyethyleneimine solution and stirred at 45-55°C for 10-15 hours. After centrifugation and washing with water, amino-modified cellulose was obtained. S2. Disperse amino-modified cellulose in water, add Ti3C2, sonicate at room temperature for 20-40 minutes, stir for 1-3 hours, and freeze dry to obtain the product.

4. The method for preparing the high thermal conductivity insulating composite material based on MXene and amino-modified cellulose according to claim 3, characterized in that, The mass ratio of cellulose, dopamine, and polyethyleneimine is 1:1:

1. The concentration of Tris-HCl buffer is 5-15 mM, the pH is 8-9, and the concentration of polyethyleneimine solution is 4-6 mg / mL.

5. The method for preparing a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose according to claim 1, characterized in that, In step 2), the preparation process of the surface-modified chopped glass fiber is as follows: the chopped glass fiber is added to a silane coupling agent solution and stirred at 50-70°C for 80-100 minutes; the silane coupling agent is at least one of KH540, KH550, KH560, KH561, KH-792, GLYMO, A-187, A-189, A-1100 and A-1120, the amount of silane coupling agent added is 1-3% of the solvent mass in the silane coupling agent solution, and the amount of surface-modified chopped glass fiber added is 1%-3% of the epoxy resin mass.

6. The method for preparing a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose according to claim 1, characterized in that, In step 1), the epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenolic epoxy resin, alicyclic epoxy resin, epoxy phenolic resin, and multifunctional epoxy resin; in step 3), the curing agent is at least one of 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylmethane, methylhexahydrophthalic anhydride, and methylnadic anhydride, and the amount added is 30%~40% of the epoxy resin mass; the accelerator is at least one of tris(dimethylaminomethyl)phenol, 2-ethyl-4-methylimidazolium, and triethylenediamine, and the amount added is 0.5%~2% of the epoxy resin mass; the defoamer is one of silicone-based defoamer, polyether defoamer, and fatty alcohol defoamer, and the amount added is 0.1%~0.5% of the epoxy resin mass.

7. The method for preparing a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose according to claim 6, characterized in that, The epoxy resin is at least one of E-51, E-44, E-51F, EPON 1001, EPON 1004, PRM-550, Tactix 742, Araldite LY 1564, EP-ON 811, Araldite GY 258, Epon 828, CYDF-170, and F-51; the accelerator is at least one of DMP-30, DMP-23, EMI-24, and triethylenediamine; and the defoamer is at least one of BYK-A 530, BYK-022, TEGO Air 910, FOAMASTER 12, and AEROSIL 200.

8. The method for preparing a high thermal conductivity insulating composite material based on MXene and amino-modified cellulose according to claim 2 or 5, characterized in that, The preparation process of the silane coupling agent solution is as follows: Anhydrous ethanol and deionized water are mixed in a volume ratio of (9~10):1 to obtain a mixed solvent. The pH value of the mixed solvent is adjusted to 4~5 with glacial acetic acid. The silane coupling agent is added to the pH-adjusted mixed solvent and stirred for 20~40 minutes to obtain the silane coupling agent solution.

9. A high thermal conductivity insulating composite material based on MXene and amino-modified cellulose prepared by any one of the preparation methods according to claims 1 to 8.

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