Aramid fiber composite film for enhancing heat transfer through interface interaction and synergistic orientation and application thereof

Abstract

The invention provides an aramid fiber composite film for enhancing heat transfer through interface interaction and synergistic orientation and application of the aramid fiber composite film, and relates to the field of thermal interface materials. Carboxylated multi-walled carbon nanotubes are added into an aramid matrix, and interface thermal resistance is reduced and phonon scattering is reduced through a strong hydrogen bond and pi-pi stacking effect between the carboxylated multi-walled carbon nanotubes and aramid and blade coating synergistic orientation of the carboxylated multi-walled carbon nanotubes and the aramid; and the high-thermal-conductivity composite film with high orientation degree, high regularity and in-plane anisotropy is formed. The heat-conducting composite film disclosed by the invention has high order and regularity, high heat conductivity, high temperature resistance and insulativity, and meets the heat dissipation requirement of a high-power chip.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of thermal interface materials, and particularly relates to an aramid composite film for enhancing heat transfer through interfacial interaction and synergistic orientation and application thereof. BACKGROUND

[0002] With the explosive development of artificial intelligence (AI) technology, we are ushering in a new era of intelligence. Chips, as the core components of artificial intelligence systems, are responsible for processing large amounts of data, running complex algorithms, and driving intelligent decision-making. However, as AI chip performance continues to improve, its power consumption and heat generation also increase dramatically, and heat dissipation has become one of the key bottlenecks restricting the development of AI technology. Thermal interface materials (TIMs), as the key medium connecting chips and heat sinks, directly determine the efficiency and stability of the thermal management system. Aramid has excellent properties such as light weight, flexibility, high strength, and insulation. More importantly, due to the presence of abundant active functional groups, aramid is easier to assemble into thin films through intramolecular and intermolecular bonds, so aramid may be an ideal candidate for the next generation of polymer-based thermal interface materials. However, the thermal conductivity of aramid is not ideal, which limits its further application.

[0003] Currently, there are two methods to improve thermal conductivity. One is to increase the orientation degree and regularity of macromolecular chains to improve the intrinsic thermal conductivity of aramid, but it is difficult to achieve. The other method is to add high thermal conductivity fillers to the aramid matrix, which is the main method adopted by most researchers, with the advantages of simplicity, efficiency, and low cost. However, the interfacial thermal resistance between the filler and the matrix may hinder the improvement of thermal conductivity. The interfacial thermal resistance is mainly caused by poor contact between the filler and the matrix. Carboxylated multi-walled carbon nanotubes (CNTs- COOH ) can provide abundant carboxyl groups (carboxylation ratio 3.86wt%) and π-π conjugated groups, and have similar one-dimensional (1D) morphological characteristics as aramid, which can be filled in 1D aramid and synergistically oriented with aramid. The present application realizes the synergistic orientation of carboxylated multi-walled carbon nanotubes and aramid through strong hydrogen bonding and π-π stacking between them, and through the scraping method, reduces the interfacial thermal resistance, forms a high-thermal-conductivity composite film with high orientation degree and regularity, and solves the problems existing in the above two methods. SUMMARY

[0004] One of the purposes of the present application is to provide an aramid composite film for enhancing heat transfer through interfacial interaction and synergistic orientation.

[0005] The second purpose of the present application is to provide an application of an aramid composite film for enhancing heat transfer through interfacial interaction and synergistic orientation in high-power chip heat dissipation.

[0006] To achieve the above object, the technical scheme adopted by the present application is:

[0007] The present application provides a kind of aramid composite film for realizing heat transfer by interface interaction and synergic orientation enhancement, the composite film includes 90-60wt% aramid matrix and 10-40wt% heat-conducting filler carboxylated multi-walled carbon nanotube, wherein heat-conducting filler carboxylated multi-walled carbon nanotube is uniformly dispersed in aramid matrix.

[0008] Preferably, the mass ratio of the aramid to the carboxylated multi-walled carbon nanotube is 6:4.

[0009] Preferably, the composite film is prepared by the following steps:

[0010] (1) aramid and carboxylated multi-walled carbon nanotube are placed in concentrated sulfuric acid medium, and are uniformly dispersed by ultrasonic and mechanical stirring, and synergic ordered orientation of aramid and carboxylated multi-walled carbon nanotube is realized by scraping method;

[0011] (2) the solution prepared in step (1) is dried and hot-pressed to form a composite film.

[0012] Preferably, in step (1), the aramid is para-aramid copolymer fiber.

[0013] Preferably, in step (1), the carboxylated multi-walled carbon nanotube has a diameter of 5-15 nm, a length of 10-30 μm, an aspect ratio of 0.67-6, a purity of ≥98wt%, and a carboxylation ratio of 3.86wt%.

[0014] Preferably, in step (2), the drying is carried out at 40°C, and the hot-pressing is carried out at 6.8kPa.

[0015] The present application provides an application of the aramid composite film for enhancing heat transfer by interface interaction and synergic orientation in high-power chip heat dissipation.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] 1. The composite film of the present application relies on strong hydrogen bonding and π-π anchoring between aramid and carboxylated multi-walled carbon nanotube to enhance the interaction force at the interface between the matrix and the heat-conducting filler, and realizes high orientation and regularity of aramid and carboxylated multi-walled carbon nanotube by scraping method, solving the problem of improving the thermal conductivity of aramid-based composite film by two traditional methods, so that the heat-conducting composite film of the present application has high order and regularity, high thermal conductivity, high temperature resistance and insulation, meeting the heat dissipation demand of high-power chip.

[0018] 2. The thermal decomposition rate of the composite film of the present application is higher than 550°C at the fastest rate.

[0019] 3、The in-plane thermal conductivity of the composite film of the present application is 6.8 W / m·K to 12.2 W / m·K, the normal thermal conductivity is 1.4 W / m·K to 2.6 W / m·K, and the minimum square resistance value is 21.43 KΩ / sq. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the interfacial interaction and synergistic orientation of the aramid composite film prepared by the present application, which synergistically enhances the heat transport. Figure 1 a is a process flow diagram for preparing aramid composite film thin film. Figure 1 b is a photo of aramid composite film. Figure 1 c is the heat flow direction and synergistic orientation of aramid composite thin film. Figure 1 d is the hydrogen bonding and π-π stacking interaction between aramid and CNTs- COOH and the anthropomorphized illustration. Figure 1 e is the interfacial phonon transport path of aramid and CNTs- COOH .

[0021] Figure 2 is the characterization of aramid composite film (denoted as ACNTs- COOH ) prepared in Examples 1-4. Figure 2 a, Figure 2 b) is the XRD spectrum of aramid, CNTs- COOH , and ACNTs- COOH thermally conductive composite film. Figure 2 c is the liquid crystal texture of ACNTs- COOH -10% and ACNTs- COOH -20% taken by POM. Figure 2 d is the SEM cross-sectional morphology and EDS element distribution of ACNTs- COOH -10% and ACNTs- COOH -20% thermally conductive composite film. Figure 2 e- Figure 2 g is the XPS spectrum of aramid and ACNTs- COOH -20% thermally conductive composite film.

[0022] Figure 3 is the thermal conductivity, square resistance and mechanical properties of ACNTs- COOH thermally conductive composite film prepared in Examples 1-4. Figure 3 a is the in-plane and normal thermal diffusivity of the composite thermally conductive film with the increase of CNTs- COOH loading. Figure 3 b is the in-plane and normal thermal conductivity. Figure 3 c is the thermal conductivity increase ratio of the composite thermally conductive film with different CNTs- COOH contents compared with pure aramid.Figure 3 d is the ACNTs- COOH - the in-plane thermal diffusivity of the 40% thermally conductive composite film. Figure 3 e is the ACNTs- COOH - the specific heat capacity of the 40% thermally conductive composite film at different temperatures. Figure 3 f is the ACNTs- COOH - the in-plane thermal conductivity of the 40% thermally conductive composite film. Figure 3 g is the ACNTs- COOH Comparison of the in-plane thermal conductivity of the thermally conductive composite film with the composite thermally conductive film with carbon nanotubes as the thermally conductive filler. Figure 3 h is the ACNTs- COOH Sheet resistance value of the thermally conductive composite film. Figure 3 i is the ACNTs- COOH TGA curve of the thermally conductive composite film.

[0023] Figure 4 Application in electronic thermal management of the composite thermally conductive film prepared in Examples 1-4. Figure 4 a is the experimental configuration of the heat dissipation of the LED lamp (20W) with the composite thermally conductive film as the thermal interface material. Figure 4 b is the infrared thermal image of the LED lamp corresponding to different running times. Figure 4 c is the change of the surface temperature of the LED lamp with the running time. Figure 4 d is the ACNTs- COOH - the temperature change of the 40% film within 600 seconds of 25 cycles. DETAILED DESCRIPTION

[0024] The application will be further described in detail below in conjunction with the accompanying drawings and specific examples.

[0025] In the following examples, the raw materials and reagents used are commercially available unless otherwise specified, and the aramid is a full para-aramid copolymer fiber produced by DuPont, USA. The carboxylated multi-walled carbon nanotubes are produced by Shanghai Adamas Reagent Co., Ltd., with a diameter of 5-15 nm, a length of 10-30 μm, an aspect ratio of 0.67-6, a purity of 98 wt%, and a carboxylation ratio of 3.86 wt%.

[0026] Example 1

[0027] An ACNTs- COOH -10% composite thermally conductive film, the thermally conductive filler carboxylated multi-walled carbon nanotubes and aramid are synergistically oriented in the plane of the composite film. The mass ratio of aramid to carboxylated multi-walled carbon nanotubes is 9:1, i.e. the mass fraction of carboxylated multi-walled carbon nanotubes is 10 wt%.

[0028] According toFigure 1 The preparation is carried out according to the flowchart shown in a, specifically as follows:

[0029] The aramid matrix and the carboxylated multi-walled carbon nanotube heat-conducting filler are placed in a concentrated sulfuric acid medium, uniformly dispersed by means of ultrasonic and mechanical stirring, and the aramid and carboxylated multi-walled carbon nanotube are cooperatively and orderly oriented by means of scraping, and the composite heat-conducting film is formed after drying and hot pressing.

[0030] Example 2

[0031] An ACNTs- that enhances heat transfer through interfacial interaction and cooperative orientation COOH -20% composite heat-conducting film, the heat-conducting filler carboxylated multi-walled carbon nanotube and aramid are cooperatively oriented in the plane of the composite film. The mass ratio of aramid and carboxylated multi-walled carbon nanotube is 8:2, that is, the mass fraction of carboxylated multi-walled carbon nanotube is 20wt%.

[0032] The preparation method is the same as that in Example 1.

[0033] Example 3

[0034] An ACNTs- that enhances heat transfer through interfacial interaction and cooperative orientation COOH -30% composite heat-conducting film, the heat-conducting filler carboxylated multi-walled carbon nanotube and aramid are cooperatively oriented in the plane of the composite film. The mass ratio of aramid and carboxylated multi-walled carbon nanotube is 7:3, that is, the mass fraction of carboxylated multi-walled carbon nanotube is 30wt%.

[0035] The preparation method is the same as that in Example 1.

[0036] Example 4

[0037] An ACNTs- that enhances heat transfer through interfacial interaction and cooperative orientation COOH -40% composite heat-conducting film, the heat-conducting filler carboxylated multi-walled carbon nanotube and aramid are cooperatively oriented in the plane of the composite film. The mass ratio of aramid and carboxylated multi-walled carbon nanotube is 6:4, that is, the mass fraction of carboxylated multi-walled carbon nanotube is 40wt%.

[0038] The preparation method is the same as that in Example 1.

[0039] Figure 1 It is a schematic diagram of the interfacial interaction and cooperative orientation of the heat-conducting composite film prepared in the present application. Figure 1 a is a flowchart of the preparation process of aramid composite film. Figure 1 b is a photo of aramid composite film. Figure 1 c is the heat flow transfer direction and cooperative orientation of aramid composite film. Figure 1 d is the hydrogen bonding and π-π stacking action between aramid and CNTs- COOH and the anthropomorphized illustration.Figure 1 e is the phonon transmission path of the interface between aramid and CNTs-COOH. The heat transfer in the aramid composite film is enhanced by interfacial interaction and cooperative orientation. COOH Provides abundant hydroxyl groups and π-π conjugated groups. CNTs- COOH Good interface bonding with aramid, and CNTs- COOH Arranged in a highly ordered aramid liquid crystal matrix, such as Figure 1 As shown in a. aramid and CNTs- COOH The close contact and long-range ordered structure provide a perfect heat conduction path inside the nanocomposite ( Figure 1 c) CNTs- COOH With morphological characteristics similar to aramid, CNTs- COOH The oriented structure can be well filled in 1D aramid. In terms of thermal conductivity, aramid and CNTs- COOH can be cooperatively oriented along the coating direction, resulting in efficient phonon transport, and aramid and CNTs- COOH The hydrogen bonding and π-π conjugation effects between the chains reduce the interfacial thermal resistance and phonon scattering by enhancing the interaction between the chains ( Figure 1 d) Phonon transport at the interface between polymer matrix and filler is as follows Figure 1 As shown in e.

[0040] Figure 2 ACNTs prepared in Example 1-4 COOH Characterization of composite thermal conductive film. ( Figure 2 a, Figure 2 b) is aramid, CNTs- COOH and ACNTs- COOH XRD spectrum of the thermally conductive composite film. Figure 2 c is to shoot ACNTs using POM- COOH -10% and ACNTs- COOH -20% liquid crystal texture. Figure 2 d is ACNTs- COOH -10% and ACNTs- COOH SEM cross section and EDS element distribution of -20% thermal conductive composite film. Figure 2 e- Figure 2 g is aramid and ACNTs- COOH -20% thermal conductive composite film XPS spectrum. This study used commercially available CNTs- COOH ACNTs- COOH film.Figure 2 a aramid film and CNTs COOH XRD patterns of the powders. The XRD pattern of pure aramid film shows a broad diffraction peak at ~20° corresponding to the (110) plane in its semi-crystalline structure. The XRD pattern of CNTs COOH has a typical diffraction peak at ~26° corresponding to the (002) plane. In the composite films, the CNTs COOH peak is low in intensity at low loading, while the CNTs COOH peak intensity increases with increasing loading Figure 2 b). Meanwhile, the position and shape of the CNTs COOH peak remain essentially unchanged, indicating that the CNTs COOH maintain their original crystal structure in the composites. Achieving liquid crystal orientation in the aramid matrix is the key to building high thermal conductivity nanocomposites, and is also the key to the cooperative orientation of aramid and CNTs COOH . The cooperative orientation of aramid and CNTs COOH can form an ordered molecular arrangement, thereby reducing phonon scattering in the thermal conduction path and improving thermal conductivity. The cooperative orientation of aramid and CNTs COOH can be characterized by the optical texture observed in the transmission mode of polarized light microscopy and the cross-sectional morphology of the film sample. Figure 2 c shows the optical structure of the composite films (ACNTs COOH -10%, ACNTs COOH -20%). The black dark areas in the optical texture are CNTs COOH . The brightly colored areas are the aramid matrix. All the films exhibit typical nematic liquid crystal optical texture, indicating that CNTs COOH of different proportions are uniformly distributed in the aramid matrix and achieve cooperative orientation with the aramid liquid crystal matrix. In addition, as the CNTs COOH content increases (10wt% to 40wt%), the black dark areas gradually increase and the field becomes brighter. Figure 2 d is the SEM cross-sectional image and EDS element distribution of the film sample (ACNTs COOH -10%, ACNTs COOH -20%). CNTs COOH are ordered along the vertical direction of the cross-section of the thermal conductive composite film, proving that the blade coating method achieves ordered arrangement of the composite film along the plane direction. It can be seen that CNTs COOH are uniformly distributed in the aramid matrix. This indicates that CNTs COOHCNTs- aramid have a good interaction and form a well-connected network at high loading. COOH CNTs- aramid matrix form a uniform orientation along the draw direction. In addition, the elemental distribution of carbon (C), nitrogen (N) and oxygen (O) elements further confirmed the uniform distribution of CNTs- COOH CNTs- aramid matrix. The uniform distribution of CNTs- COOH CNTs- aramid matrix is attributed to the strong hydrogen bonding and π-π stacking interactions between them. The EDS analysis also further confirmed the uniform distribution of carbon (yellow), nitrogen (red) and oxygen (purple) elements throughout the sample. Hydrogen bonding and π-π stacking interactions are important forms of intermolecular interactions. The synergy of hydrogen bonding and π-π stacking enhances the intermolecular interaction forces. In this work, the aramid matrix and CNTs- COOH CNTs- fillers are manifested as shifts in the binding energies in the XPS (X-ray photoelectron spectroscopy) spectra. Figure 2 e is the XPS spectra of aramid and ACNTs- COOH -20% thin film, aramid shows characteristic peaks at 284.4 eV, 399.5 eV and 532.5 eV corresponding to C1s, N 1s and O1s, respectively. ACNTs- COOH -20% shows characteristic peaks of C1s, N 1s and O1s at 285 eV, 400 eV and 532 eV, respectively. Figure 2 f-2g are the high-resolution XPS spectra of C1s and N1s. The results show that ACNTs- COOH -20% thin film, the C=O shifts to a lower binding energy of 287.92 eV, while ACNTs- COOH -20% thin film, the C=N shifts to a binding energy of 286.37 eV. In addition, ACNTs- COOH -20% thin film, the N-H has a N1s binding energy of 400.06 eV, which is higher than that of aramid. These results indicate that the chemical environment of C=O and N-H has changed, further confirming that hydrogen bonding and π-π stacking interactions have formed between aramid and CNTs- COOH .

[0041] Figure 3 are the ACNTs- COOH Thermal conductivity, sheet resistance and mechanical properties of the thermally conductive composite films prepared in Examples 1-4. Figure 3 a is the in-plane and normal thermal diffusivity of the films as the loading of CNTs- COOH increases. Figure 3 b is the in-plane and normal thermal conductivity.Figure 3 c The thermal conductivity of the composite thermal conductive films with different CNTs- COOH content increases proportionally. Figure 3 d The thermal diffusivity of the ACNTs- COOH -40% thermal conductive composite films at different temperatures. Figure 3 e The specific heat capacity of the ACNTs- COOH -40% thermal conductive composite films at different temperatures. Figure 3 f The in-plane thermal conductivity of the ACNTs- COOH -40% thermal conductive composite films at different temperatures. Figure 3 g The ACNTs- COOH -40% thermal conductive composite films prepared were compared with the in-plane thermal conductivity of the composite thermal conductive films with carbon nanotubes as the thermal conductive filler. Figure 3 h The sheet resistance value of the thermal conductive composite films. COOH Figure 3 i The TGA curve of the thermal conductive composite films. The thermal conductivity of the ACNTs- COOH -40% thermal conductive composite films was studied using LFA467 laser thermal conductivity instrument. COOH COOH The thermal conductivity of the thin films was studied. The in-plane, normal thermal diffusivity (a || , a ⊥ ) and standard deviation (s) are shown in Table S1, Table S2.

[0042] Table S1. In-plane thermal diffusivity (a || ) and standard deviation (s)

[0043]

[0044] Table S2. Normal thermal diffusivity (a ⊥ ) and standard deviation (s)

[0045]

[0046] As expected, a || depends on the CNTs- COOH loading, when the loading increases from 10wt% to 40wt%, a || ranges from 4.89 to 7.24 mm 2 / s( Figure 3 a). In contrast, a ⊥ changes little due to the lack of effective thermal conduction pathways. The thermal conductivity of the ACNTs- COOH thin films is anisotropic. Considering the interface interaction and synergistic orientation of aramid and CNTs- COOH COOH ​​​The film should exhibit good thermal conductivity in the in-plane direction. Figure 3 b gives the ACNTs- COOH In-plane thermal conductivity λ of thermally conductive composite film || and normal thermal conductivity λ ⊥ In-plane thermal conductivity λ || and normal thermal conductivity λ ⊥ According to the formula λ=α×C p ×ρ is calculated. ρ、C p The values ​​of , λ, and σ are shown in Tables S3 and S4.

[0047] Table S3. ACNTs- COOH Specific heat capacity of the film (C p ), density (ρ), in-plane thermal conductivity (λ || ) and standard deviation (σ)

[0048]

[0049] Table S4. ACNTs- COOH Specific heat capacity of the film (C p ), density (ρ), normal thermal conductivity (λ ⊥ ) and standard deviation (σ)

[0050]

[0051]

[0052] Compared with pure aramid membrane, ACNTs- COOH The composite film has excellent thermal conductivity. COOH With the increase of load, ACNTs- COOH Lambda of composite membrane || Increased dramatically. When CNTs- COOH When the loading is 40wt%, ACNTs- COOH -40% of lambda || Reaching a maximum value of 12.6W / m·K. Their λ ⊥ is 1.44~2.58W / m·K, due to CNTs- COOH The horizontal orientation of its λ ⊥ In order to further illustrate the effectiveness of improving the in-plane thermal conductivity, a parameter η is introduced, which is defined as follows: Where λ || and λ m are the in-plane thermal conductivity of the composite film and the pure aramid film respectively. Figure 3 c. It can be seen that as CNTs- COOH With the increase of load, ACNTs-COOH Lambda of composite membrane || Increased dramatically, compared to the aramid membrane || (2.42W / m·K) increased by 420%. This is because CNTs- COOH Strong hydrogen bonds between aramid and CNTs- COOH The π-π conjugated interaction between ACNTs is beneficial to reduce the COOH Interfacial thermal resistance and phonon scattering in composite films. Another important aspect is the interfacial thermal resistance and phonon scattering in ACNTs- COOH The cooperative orientation formed in the composite film constructs an efficient phonon transport path. COOH λ of the film in the parallel direction || The enhancement is attributed to CNTs- COOH In order to be applied to thermal management materials, ACNTs- COOH -40% film α at different temperatures || Research was conducted. Figure 3 d and Table S5 show the ACNTs- COOH -40% of the film's alpha || With the increase of temperature, ACNTs- COOH -40% of the film's alpha || At 200℃, the α of COOH-40% || 8.07mm 2 / s, compared with α at room temperature || It can also be observed that when heated from 25℃ to 200℃, the ACNTs- COOH -40% of the film's C p Slightly increased ( Figure 3 e). Figure 3 f and Table S6, ACNTs- COOH -40% composite film λ || It increases slightly with the increase of temperature. This is mainly because λ || The change depends on the balance between phonon excitation and scattering. When the temperature increases from 25℃ to 200℃, the excited phonons can effectively reduce the Umklapp phonon scattering, resulting in ACNTs- COOH -40% composite film λ || From the above analysis, it can be seen that within the normal device operating temperature range, ACNTs- COOH The nanocomposite film has excellent heat dissipation performance. Figure 3 g is ACNTs- COOH Comparison of the in-plane thermal conductivity of the composite membrane with the same filler content in the literature.COOH The prepared film exhibits excellent in-plane thermal conductivity. Electrical insulation is paramount in electronic thermal management. Sheet resistance, also known as film resistance, is an important metric for evaluating a film's surface resistivity, thereby helping to assess its electrical insulation capabilities. Figure 4 h and Table S7 show the ACNTs- COOH -20%, ACNTs- COOH -30% and ACNTs- COOH -40% of the sheet resistance value. When the thermal conductive filler consists only of CNTs- COOH When the composition is measured, ACNTs- COOH -40% sheet resistance at room temperature is 21.43 kΩ / sq. The lower the filler content, the higher the resistance value. This phenomenon can be attributed to the fact that the insulating aramid matrix effectively hinders the CNTs- COOH After demonstrating the excellent thermal conductivity and electrical insulation properties of the composite film, we will now discuss its thermal stability. Thermal stability is a crucial performance indicator in the processing and application of composite materials. Figure 4 e shows the ACNTs- COOH TGA graph of the film. Weight loss before 200°C is primarily due to the loss of physically adsorbed water. After 550°C, the decomposition rate of the composite film increases dramatically. These results demonstrate that the addition of fillers maintains high thermal stability.

[0053] Table S5. ACNTs- COOH -40% film in-plane thermal diffusivity (α || ) and standard deviation (σ)

[0054]

[0055] Table S6. ACNTs- COOH -40% film specific heat capacity at different temperatures (C p ), density (ρ), in-plane thermal conductivity (λ || ) and standard deviation (σ)

[0056]

[0057] Table S7. Sheet resistance (sr) and standard deviation (σ)

[0058]

[0059] Figure 4 This is the application of the composite thermally conductive film prepared in Examples 1-4 in electronic thermal management. Figure 4 a is the heat dissipation experiment configuration of LED lamp (20W) using composite thermal conductive film as thermal interface material. Figure 4b is the infrared thermal image of the LED lamp corresponding to different running time. Figure 4 c is the change of the surface temperature of the LED lamp with running time. Figure 4 d is ACNTs- COOH -40% film temperature change within 25 cycles of 600s. Efficient thermal management is of great significance to ensure the safe and stable operation of the device and prolong the service life of the device. The thermal interface material (TIM) between the LED lamp and the heat sink is the key medium for conducting the heat generated by the LED to the heat sink. In this paper, the thermal management performance of the composite film as a thermal interface material was studied, and the device schematic diagram is shown in Figure 3 a. The LED used in this study is a 20W COB LED (model 2828) that emits white light at a color temperature of 6000K. The same size (4cm*4cm) ACNTs- COOH -10% and ACNTs- COOH -40% composite films were placed between the LED lamp and the aluminum heat sink. The composite films loaded with different CNTs- COOH were placed as TIMs under the LED lamp, and their thermal conductivity was observed by infrared thermal image Figure 4 b). Within the same power generation cycle, the surface temperature of the ACNTs- COOH -40% composite film was significantly lower than that of the ACNTs- COOH -10% composite film. This further indicates that the heat dissipation performance of the ACNTs- COOH -40% composite film is superior to that of the ACNTs- COOH -10% composite film, which is consistent with the conclusion in Figure 4 b. When heat is transferred in the ACNTs- COOH composite film, the heat transfer path is more along the continuous orientation direction of CNTs- COOH and aramid. The data acquisition system also continuously recorded the change of the surface temperature of the LED lamp with time ​ c). It can be seen that after heating for 100s, the temperature rise speed of the composite film containing 40wt% CNTs- COOH is slower than that of the composite film containing 10wt% CNTs- COOH . The steady-state average temperature of the LED lamp with ACNTs- COOH -40% as TIM and the LED lamp with ACNTs- COOH -10% as TIM after lighting for 600s is 184℃ and 201℃ respectively, with an average temperature difference of 17℃. In addition, the temperature change of ACNTs- COOH -40% is very small in the thermal cycle test, indicating that the composite film has good thermal stability ​ d). ACNTs- COOHThe composite film has excellent thermal conductivity and thermal stability, and can be used as a heat dissipation material for electronic devices.

Claims

1. An aramid composite film that enhances heat transfer through interfacial interaction and synergistic orientation, characterized in that: The composite film comprises 90-60 wt% of a matrix aramid and 10-40 wt% of a thermal conductive filler carboxylation multi-walled carbon nanotubes, wherein the thermal conductive filler carboxylation multi-walled carbon nanotubes are uniformly dispersed in the aramid matrix.

2. The aramid composite film for enhancing heat transfer through interfacial interaction and synergistic orientation according to claim 1, characterized in that: The mass ratio of the aramid to the carboxylated multi-walled carbon nanotubes is 6:

4.

3. The aramid composite film according to claim 1 or 2, characterized in that: The aramid composite film is prepared by the following steps: (1) placing aramid and carboxylated multi-walled carbon nanotubes in a concentrated sulfuric acid medium, uniformly dispersing them by ultrasonic and mechanical stirring, and achieving coordinated and orderly orientation of the aramid and carboxylated multi-walled carbon nanotubes by doctor blade coating; (2) The solution obtained in step (1) is dried and hot-pressed to form a composite film.

4. The aramid composite film according to claim 1 or 2, characterized in that: In step (1), the aramid is a fully para-aramid copolymer fiber.

5. The aramid composite film with enhanced heat transfer through interfacial interaction and synergistic orientation according to claim 1 or 2, characterized in that: In step (1), the carboxylated multi-walled carbon nanotubes have a diameter of 5-15 nm, a length of 10-30 μm, an aspect ratio of 0.67-6, a purity of ≥98 wt%, and a carboxylation ratio of 3.86 wt%.

6. The aramid composite film with enhanced heat transfer through interfacial interaction and synergistic orientation according to claim 1 or 2, characterized in that: In step (2), the product is dried at 40° C. and hot pressed at 6.8 kPa.

7. Use of the aramid composite film according to any one of claims 1 to 6 that enhances heat transfer through interfacial interaction and synergistic orientation in heat dissipation of high-power chips.

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