Carbon nanotube composite precursor fiber, carbon nanotube composite material and preparation method and application of carbon nanotube composite precursor fiber and carbon nanotube composite material

Abstract

The invention relates to a carbon nanotube composite precursor fiber, a carbon nanotube composite material as well as a preparation method and application of the carbon nanotube composite precursor fiber. The carbon nanotube composite precursor fiber is prepared from the following raw materials: a carbon nanotube, an acid solution and a functional material, the carbon nanotube composite precursor fiber is prepared by liquid crystal spinning, and the liquid crystal spinning comprises the following steps: (1) mixing a carbon nanotube with an acidic solution for the first time, and then mixing the mixture with a functional material for the second time to obtain a carbon nanotube composite precursor solution; and (2) immersing the carbon nanotube composite precursor solution into a coagulating bath, and coagulating to obtain the carbon nanotube composite precursor fiber. The carbon nanotube composite material comprises the carbon nanotube composite precursor fiber. According to the invention, the carbon nanotube and the functional material are compounded by adopting a liquid crystal spinning process, so that the carbon nanotube composite material with high carbon nanotube content, high density, high orientation degree and excellent mechanical and electrical properties is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite materials, and in particular to a carbon nanotube composite precursor fiber, a carbon nanotube composite material, and a preparation method and application thereof. BACKGROUND

[0002] Carbon nanotubes (CNT) have attracted much attention due to their excellent mechanical, electrical and thermal properties, and are expected to achieve significant technological breakthroughs in many fields. However, how to effectively transfer the excellent micro-properties of carbon nanotubes to macro-materials is one of the key problems in the practical application of carbon nanotubes. Assembling carbon nanotubes into continuous materials is considered to be an important way to amplify their excellent properties and achieve industrial-scale applications. Compared with other forms of macro-assembly, carbon nanotube materials have unique advantages such as structural designability and adjustable mechanical property anisotropy. However, carbon nanotube materials still have problems such as low density, high porosity and poor inter-tube interaction, which restrict the further improvement of their performance. Silicon carbide (SiC) is a ceramic material with excellent high-temperature resistance, chemical inertness and oxidation resistance, and can maintain high fracture strength in a wide temperature range. Its products are widely used in aerospace, energy and power, semiconductor electronics and other fields. The combination of silicon carbide and carbon nanotube materials can improve the mechanical and electrical properties through interface stress transfer and conductive network construction, and enhance the electromagnetic shielding ability and other functions.

[0003] At present, the main methods for preparing carbon nanotube / ceramic composite materials include chemical vapor deposition, electrophoretic deposition and polymer-derived ceramic method.

[0004] CN103754878A discloses a method for in-situ self-growth of carbon nanotubes on the surface of silicon carbide particles, which uses chemical vapor deposition to catalytically crack and prepare carbon nanotubes on the surface of silicon carbide. However, using chemical vapor deposition method usually requires a large amount of time for depositing carbon nanotubes or ceramic materials on the substrate, which has low process efficiency and is difficult to continuously prepare.

[0005] CN119980177A discloses a method for improving the bonding strength of a silicon carbide coating on the surface of a graphite substrate and a product thereof, which uses a carbon nanotube dispersion liquid to form a carbon nanotube coating layer on the surface of the graphite substrate by electrophoresis. However, carbon nanotubes are not easy to disperse and tend to agglomerate, resulting in a decrease in the mechanical properties of the material. In addition, the carbon nanotube content of the composite material is low, which makes it difficult to exert the excellent properties of carbon nanotubes.

[0006] The polymer-derived ceramic method is beneficial to prepare high-performance composite materials due to the uniformity of the composite material composition and the controllability of the structure. CN106631079A discloses a carbon nanotube silicon carbide composite material and a preparation method thereof. The carbon nanotube silicon carbide composite material is prepared by using a traditional precursor impregnation and pyrolysis method. However, the process is prone to form a ceramic coating layer on the surface of the carbon nanotube substrate, which affects the uniformity of the material and has limited performance improvement.

[0007] Therefore, how to optimize the process to prepare a carbon nanotube composite material with high content of carbon nanotubes, high density and high orientation degree has become a problem to be solved. SUMMARY

[0008] To solve the above technical problems, the present application provides a carbon nanotube composite precursor fiber, a carbon nanotube composite material and a preparation method and application thereof. The present application innovatively uses a liquid crystal spinning process to composite carbon nanotubes and functional materials to prepare a carbon nanotube composite material with high carbon nanotube content, high density, high orientation degree, excellent mechanical and electrical properties, which is beneficial to load transfer and electron transport.

[0009] To achieve this purpose, the present application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a carbon nanotube composite precursor fiber. The preparation raw material of the carbon nanotube composite precursor fiber comprises carbon nanotubes, an acidic solution and a functional material.

[0011] The carbon nanotube composite precursor fiber is prepared by liquid crystal spinning. The liquid crystal spinning comprises the following steps:

[0012] (1) The carbon nanotubes are mixed with the acidic solution for the first time, and then mixed with the functional material for the second time to obtain a carbon nanotube composite precursor solution;

[0013] (2) The carbon nanotube composite precursor solution is immersed in a coagulation bath to obtain the carbon nanotube composite precursor fiber after coagulation.

[0014] The present application provides a carbon nanotube composite precursor fiber prepared by liquid crystal spinning technology. The carbon nanotubes are treated by an acidic solution to cause protonation and swelling, thereby reducing the van der Waals force between the carbon nanotubes. The surface of each nanotube is covered with the acidic solution, so that they repel each other and prevent aggregation. The carbon nanotubes form a dispersed and aligned liquid crystal phase. Then the carbon nanotubes are mixed with the functional material, and coagulation is carried out in a coagulation bath to make the carbon nanotube composite precursor fiber shrink and dense, thereby further improving the orientation degree and density of the carbon nanotube composite precursor fiber.

[0015] Preferably, the mass ratio of the carbon nanotubes to the functional material is 1:(0.5-1.5), for example, it can be 1:0.5, 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.4, or 1:1.5, etc.

[0016] Preferably, the carbon nanotubes include single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

[0017] Preferably, the diameter of the carbon nanotubes is 7-9 nm, for example, it can be 7 nm, 7.5 nm, 8 nm, 8.5 nm, or 9 nm, etc.

[0018] Preferably, the length of the carbon nanotubes is 100-200 μm, for example, it can be 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, or 200 μm, etc.

[0019] Preferably, the functional material includes any one or a combination of at least two of a ceramic precursor material, graphene, or MXene.

[0020] The functional material employed in the present application can be dissolved in an acidic solution to form a liquid crystal phase.

[0021] Preferably, the ceramic precursor material includes any one or a combination of at least two of silane carbonate, polycarbazirconium, polycarbonhafnium, polycarbonotantalum, or polyborosilazane.

[0022] When the functional material employed in the present application is a ceramic precursor material, the ceramic precursor material can be converted into a carbide material after sintering, the silane carbonate is sintered into silicon carbide, the polycarbazirconium is sintered into zirconium carbide, the polycarbonhafnium is sintered into hafnium carbide, the polycarbonotantalum is sintered into tantalum carbide, and the polyborosilazane is sintered into silicon boron carbonitride. After sintering, the material density is improved, and the mechanical properties of the carbon nanotube composite material are enhanced.

[0023] Preferably, the acidic solution includes chlorosulfonic acid and / or oleum.

[0024] Preferably, the concentration of the carbon nanotubes in the acidic solution is 5-20 g / L, for example, it can be 5 g / L, 6 g / L, 8 g / L, 10 g / L, 12 g / L, 14 g / L, 16 g / L, 18 g / L, or 20 g / L, etc.

[0025] The present application limits the concentration of the carbon nanotubes in the acidic solution to be 5-20 g / L. If too much acidic solution is added, the solute concentration is too low to be solidified and formed. If too little acidic solution is added, the viscosity of the precursor liquid formed by mixing the carbon nanotubes with the acidic solution is too large, and the uniformity is poor, which cannot be formed.

[0026] In a second aspect, the present application provides a method for preparing the carbon nanotube composite precursor fiber as described in the first aspect, wherein the carbon nanotube composite precursor fiber is prepared by liquid crystal spinning, and the liquid crystal spinning comprises the following steps:

[0027] (1) mixing the carbon nanotubes with an acidic solution for a first time, and then mixing the carbon nanotubes with a functional material for a second time to obtain a carbon nanotube composite precursor solution;

[0028] (2) immersing the carbon nanotube composite precursor solution into a coagulation bath to obtain the carbon nanotube composite precursor fiber after coagulation.

[0029] Preferably, the first mixing in step (1) is performed for 10-30 min, for example, 10 min, 15 min, 20 min, 25 min or 30 min, etc.

[0030] Preferably, the second mixing in step (1) is performed for 5-15 min, for example, 5 min, 6 min, 8 min, 10 min, 12 min, 14 min or 15 min, etc.

[0031] Preferably, the first mixing and the second mixing are performed in a rotary mixer.

[0032] Preferably, before step (2), the carbon nanotube composite precursor solution is filtered.

[0033] Preferably, the immersing in step (2) comprises injecting the carbon nanotube composite precursor solution into the coagulation bath.

[0034] Preferably, the injection speed is 60-90 μL / min, for example, 60 μL / min, 70 μL / min, 80 μL / min or 90 μL / min, etc.

[0035] Preferably, the injection comprises injection extrusion injection by using a syringe, and the needle gauge of the syringe is 22-30 G, for example, 22 G, 25 G, 27 G or 30 G, etc.

[0036] Preferably, the coagulant in the coagulation bath in step (2) is acetone.

[0037] Preferably, the coagulation time in step (2) is 2-5 min, for example, 2 min, 3 min, 4 min or 5 min, etc.

[0038] Preferably, after the coagulation in step (2), the carbon nanotube composite precursor fiber is wound.

[0039] Preferably, the winding speed is 10-30 r / min, for example, it can be 10 r / min, 15 r / min, 20 r / min, 25 r / min or 30 r / min, etc.

[0040] In a third aspect, the present application provides a carbon nanotube composite material, which comprises the carbon nanotube composite precursor fiber according to the first aspect.

[0041] Preferably, the carbon nanotube composite material is a carbon nanotube composite fiber.

[0042] Preferably, the carbon nanotube composite material is a carbon nanotube composite plate.

[0043] Preferably, the orientation degree of the carbon nanotubes in the carbon nanotube composite material is 12-20, for example, it can be 12, 13, 14, 15, 16, 17, 18, 19 or 20, etc.

[0044] In a fourth aspect, the present application provides a method for preparing the carbon nanotube composite material according to the third aspect, which comprises:

[0045] The carbon nanotube composite precursor fiber according to the first aspect is heat-cured to obtain the carbon nanotube composite material.

[0046] Preferably, the temperature of the heat curing is 200-240 ℃, for example, it can be 200 ℃, 210 ℃, 220 ℃, 230 ℃ or 240 ℃, etc.

[0047] Preferably, the time of the heat curing is 1-3 h, for example, it can be 1 h, 1.5 h, 2 h, 2.5 h or 3 h, etc.

[0048] Preferably, the method further comprises a step of winding and / or hot pressing before the heat curing.

[0049] Preferably, the winding process comprises a step of dropping a functional material solution.

[0050] The present application drops a functional material solution on the plate during the winding process to fill the gaps between the fibers, reduce the pores and micro-cracks in the carbon nanotube composite material, and thus improve the mechanical properties of the carbon nanotube composite material. However, too much functional material will adversely affect the electrical conductivity of the carbon nanotube composite material.

[0051] Preferably, the concentration of the functional material solution is 5-15 wt%, for example, it can be 5 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt% or 15 wt%, etc.

[0052] Preferably, the amount of the functional material solution added dropwise is 5-15 mL / g, for example, 5 mL / g, 6 mL / g, 8 mL / g, 10 mL / g, 12 mL / g, 14 mL / g, or 15 mL / g, etc., based on the mass of the functional material in the carbon nanotube composite.

[0053] Preferably, the temperature of the hot pressing is 130-170 ℃, for example, 130 ℃, 140 ℃, 150 ℃, 160 ℃, or 170 ℃, etc., and the pressure of the hot pressing is 5-15 MPa, for example, 5 MPa, 6 MPa, 8 MPa, 10 MPa, 12 MPa, 14 MPa, or 15 MPa, etc.

[0054] Preferably, the hot curing is followed by a sintering step.

[0055] When the raw material for preparing the carbon nanotube composite provided by the present application is a ceramic precursor material, the ceramic precursor material can be converted into a corresponding carbide material through a sintering step.

[0056] Preferably, the temperature of the sintering is 800-1600 ℃, for example, 800 ℃, 900 ℃, 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1400 ℃, 1500 ℃, or 1600 ℃, etc.

[0057] Preferably, the time of the sintering is 0.5-1.5 h, for example, 0.5 h, 0.6 h, 0.8 h, 1 h, 1.2 h, 1.4 h, or 1.5 h, etc.

[0058] Preferably, the sintering is carried out in an inert gas atmosphere.

[0059] Preferably, the inert gas comprises any one or a combination of at least two of nitrogen, argon, or helium.

[0060] The method for preparing the carbon nanotube composite provided by the present application includes a method for preparing carbon nanotube composite fibers and a method for preparing carbon nanotube composite plates. The method for preparing carbon nanotube composite fibers is to subject carbon nanotube composite precursor fibers to a hot curing and optionally a sintering step, thereby obtaining the carbon nanotube composite fibers. The method for preparing carbon nanotube composite plates is to subject carbon nanotube composite precursor fibers to a winding plate preparation, hot pressing, hot curing, and sintering, thereby obtaining the carbon nanotube composite plates.

[0061] In a fifth aspect, the present application provides a use of the carbon nanotube composite as described in the third aspect in aerospace materials, energy and power materials, and semiconductor and electronic materials.

[0062] Compared with the prior art, the present application has at least the following beneficial effects:

[0063] (1) The present application innovatively combines carbon nanotubes and functional composite materials by using liquid crystal spinning process, and does not use carbon nanotube dispersion liquid and surfactant and other auxiliaries in the preparation process, thereby avoiding the agglomeration of carbon nanotubes and the influence of surfactants on the performance of fibers, and obtaining carbon nanotube composite precursor fibers with high carbon nanotube content, high density and high orientation.

[0064] (2) The liquid crystal spinning technology used in the present application can realize the industrialized continuous production from carbon nanotube composite precursor fibers to carbon nanotube composite materials.

[0065] (3) The carbon nanotube composite precursor fibers provided by the present application can be directly heat-cured or optionally sintered to obtain a carbon nanotube composite fiber, or can be wound into a plate to obtain a carbon nanotube composite plate, and the carbon nanotube composite fiber and the carbon nanotube composite plate both have excellent mechanical and electrical properties, which are beneficial to load transmission and electron transmission.

[0066] (4) Specifically, the tensile strength of the carbon nanotube composite material provided by the present application can reach 0.6-3.2 Gpa, the tensile strain can reach 0.6-5.2%, and the electrical conductivity can reach 0.6-1.7 MS / m. BRIEF DESCRIPTION OF DRAWINGS

[0067] Figure 1 is an SEM image of the carbon nanotube composite fiber prepared in application example 1 of the present application, and the scale is 10 μm;

[0068] Figure 2 is an SEM image of the carbon nanotube composite fiber prepared in application example 1 of the present application, and the scale is 500 nm;

[0069] Figure 3 is an SEM image of the carbon nanotube composite fiber prepared in application example 6 of the present application, and the scale is 5 μm;

[0070] Figure 4 is an SEM image of the carbon nanotube composite fiber prepared in application example 6 of the present application, and the scale is 500 nm;

[0071] Figures 5-7 is a polarized light microscope image of the carbon nanotube composite precursor liquid prepared in example 1 of the present application, and the polarized light angles are 0°, 45° and 90°, respectively, and the scale is 100 μm;

[0072] Figure 8 is a comparison diagram of the tensile stress-tensile strain curves of the carbon nanotube composite fibers prepared in application examples 2-5 of the present application;

[0073] Figure 9A comparison chart of tensile stress-tensile strain curves of the carbon nanotube composite fiber prepared in application example 1, application example 6 and comparative application example 1 of the present application;

[0074] Figure 10 A photo of the carbon nanotube composite board prepared in application example 7 of the present application, with a scale of 1 cm. DETAILED DESCRIPTION

[0075] The technical solutions of the present application will be further described below by means of specific embodiments in combination with the accompanying drawings. However, the following examples are only simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0076] In the following specific embodiments of the present application, the specific information of the materials used is as follows:

[0077] Carbon nanotube, single-walled carbon nanotube Tuball TM , purchased from OCSiAl Company;

[0078] Polysilicocarbalkane, PCS, purchased from Ningbo Zhongxing New Material Technology Co., Ltd.

[0079] Example 1

[0080] The present embodiment provides a carbon nanotube composite precursor fiber and a preparation method thereof. The preparation raw material of the carbon nanotube composite precursor fiber comprises carbon nanotubes, an acidic solution and a functional material.

[0081] The preparation method comprises the following steps:

[0082] (1) 0.16 g of carbon nanotubes is mixed with 10 mL of chlorosulfonic acid for the first time, and placed in a rotary mixer for homogeneous rotation for 20 min. Then, 0.192 g of polycarbosilane (PCS) is added for the second time, and the mixing time is 10 min. After mixing, a carbon nanotube composite precursor solution is obtained, and the mass ratio of carbon nanotubes to polycarbosilane is 1:1.2;

[0083] (2) The carbon nanotube composite precursor solution is filtered through 400 mesh and 600 mesh filter screens in sequence, and then added to a syringe. The syringe is fixed on a syringe pump, and the setting of the injection extrusion speed is 60 μL / min. The syringe needle specification is 25 G. The carbon nanotube composite precursor solution is injected into an acetone coagulation bath for coagulation for 2 min, and then wound up at a winding speed of 15 r / min. Thus, the carbon nanotube composite precursor fiber is obtained.

[0084] The carbon nanotube composite precursor solution prepared in Example 1 is characterized by using a Zeiss Axi Vert A1 polarizing microscope. The polarizing micrograph is as shown in Figures 5-7As shown, the polarized light angles are 0°, 45° and 90° respectively, and the scale is 100 μm. It can be seen from the figure that the carbon nanotubes in the carbon nanotube composite precursor solution prepared by the embodiment 1 of the present application are uniformly dispersed, and the carbon nanotube composite precursor solution has good solubility. The solution has strong birefringence, indicating that it can form a nematic liquid crystal phase.

[0085] Embodiment 2

[0086] The embodiment provides a carbon nanotube composite precursor fiber and a preparation method thereof, and the difference from the embodiment 1 is that the amount of the carbon nanotubes is 0.246 g, the amount of the polycarbosilane is 0.106 g, and the mass ratio of the carbon nanotubes to the polycarbosilane is 1:0.43.

[0087] Embodiment 3

[0088] The embodiment provides a carbon nanotube composite precursor fiber and a preparation method thereof, and the difference from the embodiment 1 is that the amount of the carbon nanotubes is 0.211 g, the amount of the polycarbosilane is 0.141 g, and the mass ratio of the carbon nanotubes to the polycarbosilane is 1:0.67.

[0089] Embodiment 4

[0090] The embodiment provides a carbon nanotube composite precursor fiber and a preparation method thereof, and the difference from the embodiment 1 is that the amount of the carbon nanotubes is 0.176 g, the amount of the polycarbosilane is 0.176 g, and the mass ratio of the carbon nanotubes to the polycarbosilane is 1:1.

[0091] Embodiment 5

[0092] The embodiment provides a carbon nanotube composite precursor fiber and a preparation method thereof, and the difference from the embodiment 1 is that the amount of the carbon nanotubes is 0.141 g, the amount of the polycarbosilane is 0.211 g, and the mass ratio of the carbon nanotubes to the polycarbosilane is 1:1.5.

[0093] Figure 8 The tensile stress-tensile strain curves of the carbon nanotube composite precursor fibers prepared in the embodiments 2-5 are compared. It can be seen from the figure that the carbon nanotube composite precursor fiber provided by the embodiment 3 has excellent tensile effect, the tensile strength can reach 2.5 GPa, and the tensile strain is 4.3%. The polycarbosilane introduced into the carbon nanotube composite precursor fiber improves the load transfer efficiency of the carbon nanotubes in the fiber, and the tensile strength of the fiber is improved. However, when the content of the polycarbosilane is too high, the content of the polycarbosilane between the carbon nanotubes increases, and the carbon nanotubes are more prone to slip when subjected to load, resulting in a decrease in the tensile strength after reaching the peak. In addition, the polycarbosilane has a certain brittleness, and therefore, with the increase of the content of the polycarbosilane, the tensile strain of the fiber gradually decreases.

[0094] Comparative Example 1

[0095] The present comparative example provides a carbon nanotube composite precursor fiber and a preparation method thereof, and the raw material for preparing the carbon nanotube composite precursor fiber comprises carbon nanotubes and an acidic solution.

[0096] The preparation method comprises the following steps:

[0097] (1) 0.352 g of carbon nanotubes is mixed with 10 mL of chlorosulfonic acid, and is uniformly rotated in a rotary mixer for 20 min to obtain a carbon nanotube precursor solution;

[0098] (2) The carbon nanotube precursor solution is filtered through 400-mesh and 600-mesh filter screens in sequence, and is then added to a syringe. The syringe is fixed on a syringe pump, and the speed of injection extrusion is set to 60 μL / min. The specification of the needle of the syringe is 25 G. After the carbon nanotube precursor solution is injected into an acetone coagulation bath for coagulation, the carbon nanotube material precursor is obtained. After the carbon nanotube composite precursor solution is injected into the acetone coagulation bath for coagulation for 2 min, the carbon nanotube composite precursor fiber is obtained after being wound up at a winding speed of 15 r / min.

[0099] Comparative Example 2

[0100] The present comparative example provides a carbon nanotube composite precursor film and a preparation method thereof, and the raw material for preparing the carbon nanotube composite precursor film comprises carbon nanotubes and an acidic solution.

[0101] The preparation method comprises the following steps:

[0102] (1) 0.16 g of carbon nanotubes is first mixed with 10 mL of chlorosulfonic acid, and is uniformly rotated in a rotary mixer for 10 min. Then, 0.192 g of polycarbosilane is added for second mixing, and the mixing time is 5 min. The mass ratio of the carbon nanotubes to the polycarbosilane in the carbon nanotube composite precursor solution is 1:1.2.

[0103] (2) The carbon nanotube composite precursor solution is filtered through 400-mesh and 600-mesh filter screens in sequence, and is then dropped on a carrier. Another carrier is used to press the carbon nanotube composite precursor solution into a film. After being coagulated in an acetone coagulation bath for 5 min, the carbon nanotube composite precursor film is obtained.

[0104] Application Example 1

[0105] The present application example provides a carbon nanotube composite fiber and a preparation method thereof, and the carbon nanotube composite fiber comprises the carbon nanotube composite precursor fiber prepared in Example 1.

[0106] The preparation method comprises:

[0107] The carbon nanotube composite precursor fiber prepared in Example 1 is heat cured at 220 ℃ for 2 h to obtain the carbon nanotube composite fiber.

[0108] The present application uses a Hitachi SU8200 scanning electron microscope to characterize the micro-morphology of the carbon nanotube composite fiber prepared in Application Example 1, and the SEM image is shown in Figure 1 , the scale is 10 μm, and Figure 2 , the scale is 500 nm; it can be known from Figures 1-2 that the carbon nanotube composite fiber prepared in Application Example 1 has uniform surface thickness and consistent fiber orientation, and has no obvious structural defects.

[0109] Application Examples 2-5

[0110] Application Examples 2-5 respectively provide a carbon nanotube composite fiber and a preparation method thereof, which are different from Application Example 1 in that the carbon nanotube composite precursor fiber prepared in Example 1 is respectively replaced by the carbon nanotube composite precursor fiber prepared in Examples 2-5.

[0111] Application Example 6

[0112] The present application provides a carbon nanotube composite fiber and a preparation method thereof, and the carbon nanotube composite material comprises the carbon nanotube composite precursor fiber prepared in Example 1.

[0113] The preparation method comprises:

[0114] The carbon nanotube composite precursor fiber prepared in Example 1 is heat cured at 220 ℃ for 2 h, and then polycarbosilane is converted into silicon carbide (SiC) through high-temperature sintering, the sintering temperature is 1400 ℃, and the sintering time is 1 h, to obtain the carbon nanotube composite fiber.

[0115] The present application uses a Hitachi SU8200 scanning electron microscope to characterize the micro-morphology of the carbon nanotube composite fiber prepared in Application Example 6, and the SEM image is shown in Figure 3 , the scale is 5 μm, and Figure 4 , the scale is 500 nm; it can be known from Figures 3-4 that the carbon nanotube composite fiber prepared in Application Example 6 has uniform surface thickness and consistent fiber orientation, and has no obvious structural defects, and is more compact compared with the carbon nanotube composite fiber prepared in Application Example 1.

[0116] Application Example 7

[0117] The present application provides a carbon nanotube composite board and a preparation method thereof, and the carbon nanotube composite material comprises the carbon nanotube composite precursor fiber prepared in Example 1.

[0118] The preparation method comprises:

[0119] The carbon nanotube composite precursor fiber prepared in Example 1 is wound into a plate (wound into a plate by using a self-made plate winding device, the plate length is 10 cm, and the plate width is 5 cm), 2 mL of a polycarbosilane solution (10 wt%) is added dropwise to the plate, and after the solvent is volatilized, the plate is hot-pressed at 170 DEG C and 8 MPa, heat-cured at 220 DEG C for 1 h, and sintered at 1400 DEG C for 0.5 h to obtain the carbon nanotube composite plate.

[0120] Figure 10 The carbon nanotube composite plate prepared in Application Example 7 is taken as a ruler with a scale of 1 cm.

[0121] Application Example 8

[0122] The present application example provides a carbon nanotube composite plate and a preparation method thereof, and the carbon nanotube composite material comprises the carbon nanotube composite precursor fiber prepared in Example 1.

[0123] The preparation method comprises:

[0124] The carbon nanotube composite precursor fiber prepared in Example 1 is wound into a plate (wound into a plate by using a self-made plate winding device, the plate length is 10 cm, and the plate width is 5 cm), and after the solvent is volatilized, the plate is hot-pressed at 170 DEG C and 8 MPa, heat-cured at 220 DEG C for 1 h, and sintered at 1400 DEG C for 0.5 h to obtain the carbon nanotube composite plate.

[0125] Comparative Application Example 1

[0126] Comparative Application Example 1 provides a carbon nanotube composite fiber and a preparation method thereof, which is different from Application Example 1 in that the carbon nanotube composite precursor fiber prepared in Example 1 is replaced by the carbon nanotube composite precursor fiber prepared in Comparative Example 1.

[0127] Figure 9 A comparison chart of the tensile stress-tensile strain curves of the carbon nanotube composite fibers prepared in Application Example 1, Application Example 6 and Comparative Application Example 1 is shown in the figure, and it can be known from the figure that the tensile strength of the carbon nanotube composite fiber provided in Application Example 1 is more excellent than that of the carbon nanotube composite fiber provided in Comparative Application Example 1, which is mainly due to the fact that the polycarbosilane improves the load transfer efficiency of the carbon nanotubes in the composite fiber. It can be known from Comparative Application Example 1 and Application Example 6 that when the polycarbosilane is sintered into silicon carbide, the tensile strength of the carbon nanotube composite fiber is improved, but the tensile strain is slightly decreased, which is mainly due to the fact that the volume shrinkage caused by the conversion of polycarbosilane into silicon carbide improves the density of the fiber, but the intrinsic brittleness of silicon carbide leads to the decrease of the tensile strain.

[0128] Comparative Application Example 2

[0129] Comparative Application Example 2 provides a carbon nanotube composite plate and a preparation method thereof, the carbon nanotube composite material comprising a carbon nanotube composite precursor film prepared according to Comparative Example 2.

[0130] The preparation method comprises:

[0131] The carbon nanotube composite precursor film prepared according to Comparative Example 2 is heat cured at 200 ℃ for 3 h, and then sintered at 1400 ℃ for 1 h under a nitrogen atmosphere to obtain the carbon nanotube composite plate.

[0132] Test method

[0133] The carbon nanotube composite fibers or plates prepared according to Application Examples 1-8 and Comparative Application Examples 1-2 are subjected to the following performance tests:

[0134] (1) Tensile mechanical test: an Instron 3365 universal material testing machine is used to test according to the GB / T 31290-2022 “Determination of tensile properties of carbon fiber monofilament” standard;

[0135] (2) Electrical conductivity: a Keithley DAQ6510 data acquisition and recording multimeter system is used to test according to the GB / T45370-2025 “Textiles - Determination of electrical conductivity of yarns” standard.

[0136] Test results

[0137] The test results of the performance tests of the carbon nanotube composite fibers or plates prepared according to Application Examples 1-8 and Comparative Application Examples 1-2 are shown in Table 1 below:

[0138] Table 1

[0139]

[0140] From the test results, it can be seen that:

[0141] (1) From Application Example 1 and Application Examples 2-5, it can be seen that by further limiting the ratio of carbon nanotubes to functional materials, the tensile stress and tensile strain of the carbon nanotube composite fibers prepared by the present application are more balanced. When the polycarbosilane content increases, the polycarbosilane content between the carbon nanotubes increases, and the carbon nanotubes are more prone to slip when subjected to load, resulting in a decrease in tensile strength after reaching a peak. Since polycarbosilane has a certain brittleness, therefore, as the polycarbosilane content increases, the tensile strain of the precursor fiber gradually decreases.

[0142] (2) Through application example 1 and application example 6, it can be seen that the carbon nanotube composite fiber provided by the application has relatively balanced tensile strength and tensile strain before sintering, and after sintering, polycarbosilane is converted into silicon carbide, the tensile strength of the prepared carbon nanotube composite fiber is improved, but the tensile strain slightly decreases, which is mainly due to the volume shrinkage caused by the conversion of polycarbosilane into silicon carbide, which improves the density of the fiber, but the intrinsic brittleness of silicon carbide leads to the decrease of the tensile strain.

[0143] (3) Through application example 7 and application example 8, it can be seen that the carbon nanotube composite board material prepared by first preparing a carbon nanotube composite precursor fiber and then winding the board, has high strength and small strain along the fiber direction, the orientation degree of the carbon nanotube in the composite material is higher, and the mechanical properties of the board are better, but the polycarbosilane increased in the winding process leads to a slight decrease in the final electrical conductivity.

[0144] (4) Through application example 1 and comparative application example 1, it can be seen that by introducing functional materials into the carbon nanotube composite material, the tensile strength of the carbon nanotube composite fiber provided by application example 1 is more excellent than that of the pure carbon nanotube composite fiber provided by comparative application example 1, which is mainly due to the fact that polycarbosilane improves the load transfer efficiency of the carbon nanotube in the composite fiber.

[0145] (5) Through application example 7 and comparative application example 2, it can be seen that the composite material board prepared by the carbon nanotube composite precursor fiber provided by the application has higher strain and electrical conductivity than the carbon nanotube composite board provided by comparative application example 2, which adopts a direct extrusion molding process, and the overall structure and components of the carbon nanotube composite board prepared by the process are more uniform, but the tensile strength of the silicon carbide converted from polycarbosilane is weak, and it is easy to break under excessive stress.

[0146] The applicant declares that the above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the application.

Claims

1. A carbon nanotube composite precursor fiber, characterized in that, The raw materials for preparing the carbon nanotube composite precursor fiber include carbon nanotubes, acidic solution, and functional materials. The carbon nanotube composite precursor fiber was prepared by liquid crystal spinning, which includes the following steps: (1) After mixing carbon nanotubes with an acidic solution for the first time, they are then mixed with functional materials for the second time to obtain a carbon nanotube composite precursor solution; (2) The carbon nanotube composite precursor liquid is immersed in a coagulation bath and the carbon nanotube composite precursor fiber is obtained after coagulation.

2. The carbon nanotube composite precursor fiber according to claim 1, characterized in that, The mass ratio of the carbon nanotubes to the functional materials is 1:(0.5-1.5); Preferably, the carbon nanotubes include single-walled carbon nanotubes and / or multi-walled carbon nanotubes; Preferably, the diameter of the carbon nanotubes is 7-9 nm; Preferably, the length of the carbon nanotubes is 100-200 μm; Preferably, the functional material includes any one or a combination of at least two of ceramic precursor materials, graphene, or MXene; Preferably, the ceramic precursor material includes any one or a combination of at least two of polycarbosilane, polycarbozirconane, polycarbohafnane, polycarbotantalane, or polyborosilicate; Preferably, the acidic solution comprises chlorosulfonic acid and / or fuming sulfuric acid; Preferably, the concentration of the carbon nanotubes in the acidic solution is 5-20 g / L.

3. A method for preparing carbon nanotube composite precursor fibers as described in claim 1 or 2, characterized in that, The carbon nanotube composite precursor fiber was prepared by liquid crystal spinning, which includes the following steps: (1) After mixing carbon nanotubes with an acidic solution for the first time, they are then mixed with functional materials for the second time to obtain a carbon nanotube composite precursor solution; (2) The carbon nanotube composite precursor liquid is immersed in a coagulation bath and the carbon nanotube composite precursor fiber is obtained after coagulation.

4. The method for preparing carbon nanotube composite precursor fibers according to claim 3, characterized in that, The first mixing time in step (1) is 10-30 min; Preferably, the second mixing time in step (1) is 5-15 min; Preferably, the immersion in step (2) includes injecting the carbon nanotube composite precursor liquid into a coagulation bath; Preferably, the injection velocity is 60-90 μL / min; Preferably, the coagulant in the coagulation bath in step (2) is acetone; Preferably, the solidification time in step (2) is 2-5 min; Preferably, step (2) further includes winding after solidification; Preferably, the winding speed is 10-30 r / min.

5. A carbon nanotube composite material, characterized in that, The carbon nanotube composite material includes the carbon nanotube composite precursor fiber as described in claim 1 or 2.

6. The carbon nanotube composite material according to claim 5, characterized in that, The carbon nanotube composite material is a carbon nanotube composite fiber; Preferably, the carbon nanotube composite material is a carbon nanotube composite plate; Preferably, the degree of orientation of the carbon nanotubes in the carbon nanotube composite material is 12-20.

7. A method for preparing a carbon nanotube composite material as described in claim 5 or 6, characterized in that, The preparation method includes: The carbon nanotube composite material is obtained by thermosetting the carbon nanotube composite precursor fiber as described in any one of claims 1 or 2.

8. The method for preparing the carbon nanotube composite material according to claim 7, characterized in that, The thermosetting temperature is 200-240 ℃; Preferably, the thermosetting time is 1-3 hours.

9. The method for preparing the carbon nanotube composite material according to claim 7 or 8, characterized in that, The process prior to thermosetting also includes a winding and / or hot pressing step; Preferably, the winding process includes a step of adding a functional material solution; Preferably, the concentration of the functional material in the functional material solution is 5-15 wt%; Preferably, the amount of the functional material solution added is 5-15 mL / g, based on the mass of the functional material in the carbon nanotube composite material; Preferably, the hot pressing temperature is 130-170 ℃, and the hot pressing pressure is 5-15 MPa; Preferably, the thermosetting process further includes a sintering step; Preferably, the sintering temperature is 800-1600 ℃; Preferably, the sintering time is 0.5-1.5 h; Preferably, the sintering is carried out in an inert gas atmosphere; Preferably, the inert gas includes any one or a combination of at least two of nitrogen, argon, or helium.

10. The application of a carbon nanotube composite material as described in claim 5 or 6 in aerospace materials, energy and power materials, and semiconductor electronic materials.

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