A method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of a conductive fiber

Abstract

The application discloses a method for quickly constructing a bone-shaped porous carbon nanotube layer on the surface of a conductive fiber, which comprises the following steps: firstly, performing carboxylation on carbon nanotubes (CNTs); secondly, preparing a carbon nanotube solution; thirdly, removing sizing agent from the conductive fiber; fourthly, configuring an electrophoresis solution; and finally, performing electrophoretic deposition of the bone-shaped porous carbon nanotube layer; the application quickly constructs a designed bone-shaped porous carbon nanotube layer on the surface of the fiber by using an intermittent electrode plate, improves the mechanical properties of the carbon fiber and the interface properties of the composite material, and is expected to be industrialized.

Description

Technical Field

[0001] This invention relates to the field of conductive fiber surface modification technology, and in particular to a method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of conductive fibers. Background Technology

[0002] Carbon fiber reinforced polymer composites (CFRPs) have been widely used in high-value-added products requiring high strength-to-weight ratio and stiffness due to their excellent comprehensive properties, especially their outstanding structural design, lightweight and high strength, and integrated structural and functional characteristics. These applications include aerospace, weaponry, automobiles, civil infrastructure, and sporting goods.

[0003] The interfacial characteristics between the fiber reinforcement and the matrix are one of the key factors affecting the overall performance of CFRPs. For example, strong adhesion at the interface ensures good stress transfer from the matrix to the fiber, leading to increased overall strength but low toughness. Conversely, weak adhesion at the interface allows for energy dissipation and stress redistribution around cracks and defects, resulting in increased toughness but low strength. Structures such as bone-like fibers can simultaneously improve the strength and toughness of composites. Existing laser etching and plasma bombardment methods can construct bone-like fiber structures; however, both methods introduce defects on the fiber surface, reducing fiber strength (CN113417135A, A method for modifying carbon fibers based on the concave-convex structure of one-dimensional nanomaterials and its preparation). Carbon nanotubes (CNTs) are commonly used as a reinforcing phase in fiber-reinforced resin matrix composites to promote stress transfer between the resin matrix and fibers. Common modification methods that introduce CNTs onto the fiber surface can improve the interfacial properties between the fiber and resin, but often result in significant losses in mechanical properties and have disadvantages such as environmental pollution, low efficiency, cumbersome operation, and difficulty in industrialization. In recent years, carbon nanotubes have been deposited on the surface of fibers using electrophoretic deposition. This method can enhance the mechanical properties of fibers while improving the interfacial strength of carbon fiber composites (Jiang, et al. Influence of carbon nanotube coatings on carbon fiber by ultrasonically assisted electrophoretic deposition on its composite interfacial property[J]. Polymers 2016,8(8),302.). However, this method also has some drawbacks, such as long deposition time and the fact that it can only improve the interfacial strength of composites without structural design, while reducing toughness.

[0004] Therefore, there is an urgent need for a new carbon fiber modification technology that can form a structurally designed carbon nanotube layer on the surface of carbon fibers in a short time, which can improve the interfacial properties of carbon fiber composites while enhancing the mechanical properties of the fibers. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of conductive fibers. By using intermittent electrode plates, a designed bone-like porous carbon nanotube layer is rapidly constructed on the fiber surface, which improves the mechanical properties of carbon fibers and the interfacial properties of composite materials, and is expected to be industrialized.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of a conductive fiber includes the following steps:

[0008] 1) Carboxylation of carbon nanotubes (CNTs): CNTs were immersed in a mixed solution of HNO3 / H2SO4 (1 / 3, v / v) and magnetically stirred at 50-100℃ for 5-12 hours at atmospheric temperature to remove impurities and introduce carboxyl groups on the surface of CNTs; after surface modification, the mixture was diluted with deionized water and filtered through a membrane, then repeatedly washed with pure water to reach a neutral pH value, and dried under vacuum at 50-100℃ for 12-36 hours.

[0009] 2) Preparation of carbon nanotube solution: The carboxylated carbon nanotubes and dispersant from step 1) are dispersed in a solvent and ultrasonically cleaned for 1-3 hours to form a uniformly dispersed carbon nanotube solution.

[0010] 3) Removing sizing agent from conductive fibers: Place the conductive fibers in an acetone solution and react at a constant temperature of 50-100℃ for 12-36 hours. Wash the fibers several times with anhydrous ethanol and deionized water alternately, and then dry the washed conductive fibers at 60-100℃ for 12-36 hours.

[0011] 4) Preparation of electrophoresis solution: Add metal salt to the uniformly dispersed carbon nanotube solution prepared in step 2), sonicate for 0.5-1h, the metal ions will be adsorbed on the surface of carbon nanotubes, thus making the carbon nanotubes positively charged, and then centrifuge at 5000-10000r / min for 10-30min; take the supernatant as the electrophoresis solution.

[0012] 5) Electrophoretic Deposition of Bone-like Porous Carbon Nanotube Layers: The bone-like porous carbon nanotube layer electrophoretic deposition system is a reaction generating device for depositing bone-like porous carbon nanotube layers on the surface of continuous conductive fiber bundles. It consists of an electrophoresis apparatus, an electrolytic cell, and a roller device. The roller device is placed in the electrolytic cell, and the continuous conductive fiber bundles pass through the roller and into the electrophoretic solution, through stainless steel electrode plates, and then out of the electrolytic cell via the roller. In the electrolytic cell, the stainless steel electrode plates with discontinuous structures are connected to the positive electrode of the electrophoresis apparatus as the positive electrode, with a discontinuity spacing of 50-300 μm. The conductive fibers are connected to the negative electrode of the electrophoresis apparatus as the negative electrode, with a spacing of 1-2 cm between the two stainless steel electrode plates. The applied voltage is 10-30 V. Under the action of an electric field... Under these conditions, the carbon nanotubes, which adsorb metal ions and carry a positive charge, move towards the negatively charged electrode and are deposited on the surface of the conductive fiber. Due to the discontinuous structure of the stainless steel electrode plate, the area where the conductive fiber faces the stainless steel electrode plate deposits faster than other areas. The metal ions react with electrons and water to generate metal hydroxide, which acts as a binder to bond the conductive fiber and the carbon nanotubes. The water on the surface of the conductive fiber is electrolyzed to generate hydrogen gas, which then escapes, completing the construction of the bone-like porous carbon nanotube layer. After a deposition time of 20-60 seconds, the conductive fiber with the bone-like porous carbon nanotube layer is repeatedly washed with ethanol and water for 1-3 minutes each to obtain the conductive fiber with the bone-like porous carbon nanotube layer.

[0013] In step 2), the dispersant is N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP).

[0014] In step 2), the mass ratio of carbon nanotubes to dispersant is 1:(0.1-0.3).

[0015] In step 2), the mass ratio of carbon nanotubes to solvent volume is (0.1 mg - 1 mg): 1 ml.

[0016] In step 3), the conductive fiber is carbon fiber, polyacetylene fiber, or polyaniline fiber.

[0017] In step 4), the metal salt is magnesium nitrate or magnesium chloride.

[0018] In step 4), the mass ratio of metal salt to carbon nanotubes is 1:(0.1-0.5).

[0019] The beneficial effects of this invention are as follows:

[0020] This invention is a surface modification method that uses intermittent electrode plates to rapidly construct a bone-like porous carbon nanotube layer on the fiber surface, which solves the problem of long electrophoretic deposition time in traditional electrophoretic deposition methods. Traditional methods require about 1 hour, while this invention shortens it to 20-60 seconds.

[0021] Traditional electrophoretic deposition of conductive fibers can improve the interfacial shear strength by about 10%, while this invention can improve it by 30-70% and simultaneously improve the interfacial fracture toughness by 50-130%. In addition, this method has the advantages of being environmentally friendly, having low risk, and having controllable bone spacing.

[0022] Carboxylated carbon nanotubes react with resins and increase mechanical interlocking with the matrix, improving the surface energy and wettability of fibers, thereby enhancing the interfacial shear strength of composite materials.

[0023] The deposited bone-like porous carbon nanotube layer can deflect cracks and increase energy dissipation. In addition, the fracture of metal hydroxide can further increase energy dissipation, thereby increasing the interfacial fracture toughness of the composite material. At the same time, the bone-like porous carbon nanotube layer deposited on the surface of conductive fibers can repair defects on the surface of conductive fibers, thereby improving the tensile strength of the single filament of conductive fibers. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the bone-like porous carbon nanotube layer electrophoretic deposition system according to an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of a stainless steel electrode plate with an intermittent structure according to an embodiment of the present invention.

[0026] Figure 3 This is a scanning electron microscope image of carbon fibers with a bone-like porous carbon nanotube layer, as shown in Example 1.

[0027] Figure 4 This is a magnified scanning electron microscope image of the carbon fiber with a bone-like porous carbon nanotube layer in Example 1.

[0028] Figure 5 The surface contact angles of the carbon fibers before and after modification in Example 1 are shown.

[0029] Figure 6 The surface energy of the carbon fibers before and after modification in Example 1 is given.

[0030] Figure 7 The values ​​represent the Weibull modulus of the single fiber tensile strength of carbon fibers before and after modification in Example 1, as well as the interfacial shear strength and interfacial fracture toughness of carbon fibers / epoxy resin. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0032] Example 1: A method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of a conductive fiber, comprising the following steps:

[0033] 1) Carboxylation of carbon nanotubes (CNTs): CNTs were immersed in a mixed solution of HNO3 / H2SO4 (1 / 3, v / v) and magnetically stirred at 50°C for 5 hours at atmospheric temperature to remove impurities and introduce carboxyl groups on the surface of CNTs; after surface modification, the mixture was diluted with deionized water and filtered through a membrane, then repeatedly washed with pure water to reach a neutral pH value, and dried under vacuum at 50°C for 12 hours.

[0034] 2) Preparation of carbon nanotube solution: 0.1g of carboxylated carbon nanotubes and 0.01g of N-methylpyrrolidone (NMP) from step 1) were dispersed in 1L of solvent and ultrasonically cleaned for 3h to form a uniformly dispersed carbon nanotube solution.

[0035] 3) Removal of sizing agent from conductive fibers: The carbon fibers are placed in an acetone solution and reacted at a constant temperature of 50°C for 12 hours. They are then washed several times with alternating anhydrous ethanol and deionized water, and the washed carbon fibers are dried at 60°C for 12 hours.

[0036] 4) Preparation of electrophoresis solution: Add 0.01g magnesium nitrate to the uniformly dispersed carbon nanotube solution prepared in step 2), sonicate for 0.5h, magnesium ions will be adsorbed on the surface of carbon nanotubes, thus making the carbon nanotubes positively charged, and then centrifuge at 5000r / min for 10min; take the supernatant as the electrophoresis solution.

[0037] 5) Electrophoretic deposition of bone-like porous carbon nanotube layers: Refer to Figure 1 , Figure 2 The bone-like porous carbon nanotube layer electrophoretic deposition system is a reaction device for depositing bone-like porous carbon nanotube layers on the surface of continuous conductive fiber bundles. It consists of an electrophoresis apparatus, an electrolytic cell, and a roller assembly. The roller assembly is placed in the electrolytic cell, and the continuous conductive fiber bundles pass through the roller and into the electrophoretic solution, through stainless steel electrode plates, and then out of the electrolytic cell via the roller. In the electrolytic cell, the stainless steel electrode plates with an intermittent structure serve as the positive electrode, connected to the positive electrode of the electrophoresis apparatus with an intermittent spacing of 50 μm. The conductive fibers serve as the negative electrode, connected to the negative electrode of the electrophoresis apparatus with a spacing of 1 cm between the two stainless steel electrode plates. The applied voltage is 10 V. Under the influence of the electric field, metal ions are adsorbed and... Positively charged carbon nanotubes move toward the negatively charged electrode and are deposited on the surface of the conductive fiber. Due to the discontinuous structure of the stainless steel electrode plate, the area where the conductive fiber faces the stainless steel electrode plate deposits faster than other areas. Metal ions react with electrons and water to generate metal hydroxide, which acts as a binder to bond the conductive fiber and carbon nanotubes. Water on the surface of the conductive fiber is electrolyzed to generate hydrogen gas, which escapes, completing the construction of the bone-like porous carbon nanotube layer. After a deposition time of 20 seconds, the conductive fiber with the bone-like porous carbon nanotube layer is repeatedly washed with ethanol and water for 1 minute each to obtain the conductive fiber with the bone-like porous carbon nanotube layer.

[0038] This embodiment utilizes a surface modification method involving the rapid construction of a bone-like porous carbon nanotube layer on the fiber surface using intermittent electrode plates, shortening the electrophoresis time to 20 seconds. Scanning electron microscopy images show that the bone-like porous carbon nanotube layer is deposited on the fiber surface. The interfacial shear strength between the conductive fiber and the resin is increased by 60%, while the interfacial fracture toughness is increased by 120%. Furthermore, the Weibull modulus of the single fiber tensile strength of the conductive fiber is increased by 6%. Moreover, the continuous processing method facilitates industrial production.

[0039] Reference Figure 3 , Figure 4 , Figure 3 The image shown is a scanning electron microscope image of the desized carbon fiber in this embodiment. It can be seen that the surface of the desized carbon fiber has many shallow and narrow grooves along the longitudinal direction. Figure 4 This is a magnified scanning electron microscope image of the carbon fiber with a bone-like porous carbon nanotube layer in this embodiment. It can be seen that the fiber surface is covered with a layer of bone-like porous carbon nanotubes. This structure can increase the mechanical interlocking force between the fiber and the resin.

[0040] Reference Figure 5 , Figure 6 , Figure 7 , Figure 5 The figures show the surface contact angles of the carbon fibers before and after modification in this embodiment. It can be seen that the contact angles of the modified carbon fibers are reduced, which is due to the deposition of carboxylated carbon nanotubes. Figure 6 The surface energy of the carbon fiber before and after modification in this embodiment is shown. It can be seen that the surface energy of the modified carbon fiber increases. This is because the surface roughness increases after deposition and the carbon fiber contains a large number of carboxyl groups. Figure 7 The tensile strength of the carbon fiber before and after modification, and the interfacial shear strength and interfacial fracture toughness of the carbon fiber / epoxy resin in this embodiment are shown. The Weibull modulus of the tensile strength of the modified carbon fiber increases because the defects on the carbon fiber surface are filled and repaired by the bone-like porous carbon nanotube layer. The interfacial shear strength of the modified carbon fiber is significantly improved because the carboxylated carbon nanotubes react with the resin and increase the mechanical interlocking with the matrix, thereby increasing the surface energy and wettability of the fiber and thus improving the interfacial shear strength of the composite material. The interfacial fracture toughness of the modified carbon fiber is significantly improved because the bone-like porous carbon nanotube layer can deflect cracks and increase energy dissipation. In addition, the fracture of metal hydroxide can further increase energy dissipation, thereby increasing the interfacial fracture toughness of the composite material.

[0041] Table 1 shows the XPS elemental content analysis of carbon fibers before and after electrophoretic deposition in this embodiment. After electrophoretic deposition, the oxygen and magnesium content on the carbon fiber surface increased, proving that carbon nanotubes and magnesium hydroxide were indeed deposited on the carbon fiber surface.

[0042] Table 1

[0043]

[0044] Example 2: A method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of a conductive fiber, comprising the following steps:

[0045] 1) Carboxylation of carbon nanotubes (CNTs): CNTs were immersed in a mixed solution of HNO3 / H2SO4 (1 / 3, v / v) and magnetically stirred at 100°C for 12 hours at atmospheric temperature to remove impurities and introduce carboxyl groups on the surface of CNTs; after surface modification, the mixture was diluted with deionized water and filtered through a membrane, then repeatedly washed with pure water to reach a neutral pH value, and dried under vacuum at 100°C for 36 hours.

[0046] 2) Preparation of carbon nanotube solution: 0.1 g of carboxylated carbon nanotubes and 0.03 g of N,N-dimethylformamide (DMF) from step 1) were dispersed in 0.1 L of solvent and ultrasonically cleaned for 1 h to form a uniformly dispersed carbon nanotube solution.

[0047] 3) Removal of sizing agent from conductive fibers: The carbon fibers are placed in an acetone solution and reacted at a constant temperature of 100°C for 36 hours. They are then washed several times with alternating anhydrous ethanol and deionized water, and the washed carbon fibers are dried at 100°C for 36 hours.

[0048] 4) Preparation of electrophoresis solution: Add 0.05g magnesium nitrate to the uniformly dispersed carbon nanotube solution prepared in step 2), sonicate for 1 hour, magnesium ions will be adsorbed on the surface of carbon nanotubes, thereby making the carbon nanotubes positively charged, and then centrifuge at 10000r / min for 30min; take the supernatant as the electrophoresis solution.

[0049] 5) Electrophoretic Deposition of Bone-like Porous Carbon Nanotube Layers: The bone-like porous carbon nanotube layer electrophoretic deposition system is a reaction generating device for depositing bone-like porous carbon nanotube layers on the surface of continuous conductive fiber bundles. It consists of an electrophoresis apparatus, an electrolytic cell, and a roller device. The roller device is placed in the electrolytic cell, and the continuous conductive fiber bundle passes through the roller and into the electrophoretic solution, through stainless steel electrode plates, and then exits the electrolytic cell via the roller. In the electrolytic cell, the stainless steel electrode plates with a discontinuous structure are connected to the positive electrode of the electrophoresis apparatus as the positive electrode, with a discontinuity spacing of 300 μm. The conductive fibers are connected to the negative electrode of the electrophoresis apparatus as the negative electrode, with a spacing of 2 cm between the two stainless steel electrode plates. The applied voltage is 30 V. Under the action of an electric field... Under these conditions, the carbon nanotubes, which adsorb metal ions and carry a positive charge, move to the negatively charged electrode and are deposited on the surface of the conductive fiber. Due to the discontinuous structure of the stainless steel electrode plate, the area where the fiber faces the stainless steel electrode plate deposits faster than other areas. The metal ions react with electrons and water to generate metal hydroxide, which acts as a binder to bond the conductive fiber and the carbon nanotubes. The water on the surface of the conductive fiber is electrolyzed to generate hydrogen gas, which then escapes, completing the construction of the bone-like porous carbon nanotube layer. After a deposition time of 60 seconds, the conductive fiber with the bone-like porous carbon nanotube layer is repeatedly washed with ethanol and water for 3 minutes each, thus obtaining the conductive fiber with the bone-like porous carbon nanotube layer.

[0050] The interfacial shear strength of this surface-modified carbon fiber composite material, which utilizes intermittent electrode plates to rapidly construct a bone-like porous carbon nanotube layer on the fiber surface, is improved by 30%, while the interfacial fracture toughness is improved by 50%. In addition, the Weibull modulus of the single fiber tensile strength of the carbon fiber is improved by 10%.

[0051] Example 3: A method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of a conductive fiber, comprising the following steps:

[0052] 1) Carboxylation of carbon nanotubes (CNTs): CNTs were immersed in a mixed solution of HNO3 / H2SO4 (1 / 3, v / v) and magnetically stirred at 80°C for 10 hours at atmospheric temperature to remove impurities and introduce carboxyl groups on the surface of CNTs; after surface modification, the mixture was diluted with deionized water and filtered through a membrane, then repeatedly washed with pure water to reach a neutral pH value, and dried under vacuum at 80°C for 24 hours.

[0053] 2) Preparation of carbon nanotube solution: 0.1 g of carboxylated carbon nanotubes and 0.02 g of N,N-dimethylformamide (DMF) from step 1) were dispersed in 0.5 L of solvent and ultrasonically cleaned for 1 h to form a uniformly dispersed carbon nanotube solution.

[0054] 3) Removal of sizing agent from conductive fibers: The carbon fibers are placed in an acetone solution and reacted at a constant temperature of 80°C for 24 hours. They are then washed several times with alternating anhydrous ethanol and deionized water, and the washed carbon fibers are dried at 80°C for 24 hours.

[0055] 4) Preparation of electrophoresis solution: Add 0.06g of magnesium nitrate to the uniformly dispersed carbon nanotube solution prepared in step 2), sonicate for 1 hour, magnesium ions will be adsorbed on the surface of carbon nanotubes, thus making the carbon nanotubes positively charged, and then centrifuge at 8000r / min for 20min; take the supernatant as the electrophoresis solution.

[0056] 5) Electrophoretic Deposition of Bone-like Porous Carbon Nanotube Layers: The bone-like porous carbon nanotube layer electrophoretic deposition system is a reaction generating device for depositing bone-like porous carbon nanotube layers on the surface of continuous conductive fiber bundles. It consists of an electrophoresis apparatus, an electrolytic cell, and a roller device. The roller device is placed in the electrolytic cell, and the continuous conductive fiber bundle passes through the roller and into the electrophoretic solution, through stainless steel electrode plates, and then exits the electrolytic cell via the roller. The stainless steel electrode plates with discontinuous structures in the electrolytic cell serve as the positive electrode and are connected to the positive electrode of the electrophoresis apparatus, with a discontinuity spacing of 100 μm. The conductive fibers serve as the negative electrode and are connected to the negative electrode of the electrophoresis apparatus, with a spacing of 1.5 cm between the two stainless steel electrode plates. The applied voltage is 20 V. Under the electric field... Under the influence of the electrode, the carbon nanotubes that adsorb metal ions and are positively charged will move to the negatively charged electrode and be deposited on the surface of the conductive fiber. Due to the discontinuous structure of the stainless steel electrode plate, the area of ​​the fiber facing the stainless steel electrode plate has a faster deposition rate than other areas. The metal ions react with electrons and water to generate metal hydroxide, which acts as a binder to bond the conductive fiber and the carbon nanotubes. The water on the surface of the conductive fiber will be electrolyzed to generate hydrogen gas, which will then escape, completing the construction of the bone-like porous carbon nanotube layer. After a deposition time of 30 seconds, the conductive fiber with the bone-like porous carbon nanotube layer is repeatedly washed with ethanol and water for 2 minutes each to obtain the conductive fiber with the bone-like porous carbon nanotube layer.

[0057] The interfacial shear strength of this surface-modified carbon fiber composite material, which utilizes intermittent electrode plates to rapidly construct a bone-like porous carbon nanotube layer on the fiber surface, is improved by 50%, while the interfacial fracture toughness is improved by 90%. In addition, the Weibull modulus of the single fiber tensile strength is improved by 7%.

[0058] Example 4: A method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of a conductive fiber, comprising the following steps:

[0059] 1) Carboxylation of carbon nanotubes (CNTs): CNTs were immersed in a mixed solution of HNO3 / H2SO4 (1 / 3, v / v) and magnetically stirred at 80°C for 9 hours at atmospheric temperature to remove impurities and introduce carboxyl groups on the surface of CNTs; after surface modification, the mixture was diluted with deionized water and filtered through a membrane, then repeatedly washed with pure water to reach a neutral pH value, and dried under vacuum at 70°C for 24 hours.

[0060] 2) Preparation of carbon nanotube solution: 0.1 g of carboxylated carbon nanotubes and 0.03 g of N,N-dimethylformamide (DMF) from step 1) were dispersed in 0.5 L of solvent and ultrasonically cleaned for 1 h to form a uniformly dispersed carbon nanotube solution.

[0061] 3) Removal of sizing agent from conductive fibers: Place polyacetylene fibers in acetone solution and react at a constant temperature of 80°C for 24 hours. Wash the fibers several times with alternating anhydrous ethanol and deionized water, and then dry the washed polyacetylene fibers at 80°C for 24 hours.

[0062] 4) Preparation of electrophoresis solution: Add 0.05g of magnesium chloride to the uniformly dispersed carbon nanotube solution prepared in step 2), sonicate for 1 hour, magnesium ions will be adsorbed on the surface of carbon nanotubes, thereby making the carbon nanotubes positively charged, and then centrifuge at 9000 r / min for 20 min; take the supernatant as the electrophoresis solution.

[0063] 5) Electrophoretic Deposition of Bone-like Porous Carbon Nanotube Layers: The bone-like porous carbon nanotube layer electrophoretic deposition system is a reaction generating device for depositing bone-like porous carbon nanotube layers on the surface of continuous conductive fiber bundles. It consists of an electrophoresis apparatus, an electrolytic cell, and a roller device. The roller device is placed in the electrolytic cell, and the continuous conductive fiber bundle passes through the roller and into the electrophoretic solution, through stainless steel electrode plates, and then exits the electrolytic cell via the roller. The stainless steel electrode plates with discontinuous structures in the electrolytic cell serve as the positive electrode and are connected to the positive electrode of the electrophoresis apparatus, with a discontinuity spacing of 100 μm. The conductive fibers serve as the negative electrode and are connected to the negative electrode of the electrophoresis apparatus, with a spacing of 1.5 cm between the two stainless steel electrode plates. The applied voltage is 20 V. Under the electric field... Under the influence of the electrode, the carbon nanotubes that adsorb metal ions and are positively charged will move to the negatively charged electrode and be deposited on the surface of the conductive fiber. Due to the discontinuous structure of the stainless steel electrode plate, the area of ​​the fiber facing the stainless steel electrode plate has a faster deposition rate than other areas. The metal ions react with electrons and water to generate metal hydroxide, which acts as a binder to bond the conductive fiber and the carbon nanotubes. The water on the surface of the conductive fiber will be electrolyzed to generate hydrogen gas, which will then escape, completing the construction of the bone-like porous carbon nanotube layer. After a deposition time of 30 seconds, the conductive fiber with the bone-like porous carbon nanotube layer is repeatedly washed with ethanol and water for 2 minutes each to obtain the conductive fiber with the bone-like porous carbon nanotube layer.

[0064] The interfacial shear strength of this surface-modified polyacetylene fiber composite material, which utilizes intermittent electrode plates to rapidly construct a bone-like porous carbon nanotube layer on the fiber surface, is improved by 54%, while the interfacial fracture toughness is improved by 86%; in addition, the Weibull modulus of the single fiber tensile strength is improved by 6%.

[0065] Example 5: A method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of a conductive fiber, comprising the following steps:

[0066] 1) Carboxylation of carbon nanotubes (CNTs): CNTs were immersed in a mixed solution of HNO3 / H2SO4 (1 / 3, v / v) and magnetically stirred at 90°C for 10 hours at atmospheric temperature to remove impurities and introduce carboxyl groups on the surface of CNTs; after surface modification, the mixture was diluted with deionized water and filtered through a membrane, then repeatedly washed with pure water to reach a neutral pH value, and dried under vacuum at 70°C for 24 hours.

[0067] 2) Preparation of carbon nanotube solution: 0.1 g of carboxylated carbon nanotubes and 0.04 g of N,N-dimethylformamide (DMF) from step 1) were dispersed in 0.7 L of solvent and ultrasonically cleaned for 2 h to form a uniformly dispersed carbon nanotube solution.

[0068] 3) Removal of sizing agent from conductive fibers: Place polyaniline fibers in acetone solution and react at a constant temperature of 80°C for 24 hours. Wash the fibers several times with alternating anhydrous ethanol and deionized water, and then dry the washed polyaniline fibers at 80°C for 24 hours.

[0069] 4) Preparation of electrophoresis solution: Add 0.07g of magnesium chloride to the uniformly dispersed carbon nanotube solution prepared in step 2), sonicate for 1 hour, magnesium ions will be adsorbed on the surface of carbon nanotubes, thereby making the carbon nanotubes positively charged, and then centrifuge at 9000 r / min for 30 min; take the supernatant as the electrophoresis solution.

[0070] 5) Electrophoretic Deposition of Bone-like Porous Carbon Nanotube Layers: The bone-like porous carbon nanotube layer electrophoretic deposition system is a reaction generating device for depositing bone-like porous carbon nanotube layers on the surface of continuous conductive fiber bundles. It consists of an electrophoresis apparatus, an electrolytic cell, and a roller device. The roller device is placed in the electrolytic cell, and the continuous conductive fiber bundle passes through the roller and into the electrophoretic solution, through stainless steel electrode plates, and then exits the electrolytic cell via the roller. In the electrolytic cell, the stainless steel electrode plates with an intermittent structure serve as the positive electrode and are connected to the positive electrode of the electrophoresis apparatus, with an intermittent spacing of 200 μm. The conductive fibers serve as the negative electrode and are connected to the negative electrode of the electrophoresis apparatus, with a spacing of 1.5 cm between the two stainless steel electrode plates. The applied voltage is 20 V. Under the electric field... Under the influence of the electrode, the carbon nanotubes that adsorb metal ions and are positively charged will move to the negatively charged electrode and be deposited on the surface of the conductive fiber. Due to the discontinuous structure of the stainless steel electrode plate, the area of ​​the fiber facing the stainless steel electrode plate has a faster deposition rate than other areas. The metal ions react with electrons and water to generate metal hydroxide, which acts as a binder to bond the conductive fiber and the carbon nanotubes. The water on the surface of the conductive fiber will be electrolyzed to generate hydrogen gas, which will then escape, completing the construction of the bone-like porous carbon nanotube layer. After a deposition time of 30 seconds, the conductive fiber with the bone-like porous carbon nanotube layer is repeatedly washed with ethanol and water for 1 minute each to obtain the conductive fiber with the bone-like porous carbon nanotube layer.

[0071] The interfacial shear strength of this surface-modified polyacetylene fiber composite material, which utilizes intermittent electrode plates to rapidly construct a bone-like porous carbon nanotube layer on the fiber surface, is improved by 70%, while the interfacial fracture toughness is improved by 130%. In addition, the Weibull modulus of the single fiber tensile strength is improved by 8%.

Claims

1. A method for rapidly constructing a bone-like porous carbon nanotube layer on the surface of a conductive fiber, characterized in that, Includes the following steps: 1) Carboxylation of carbon nanotubes (CNTs): CNTs were immersed in a mixed solution of HNO3 / H2SO4, wherein HNO3 / H2SO4 was 1 / 3 (v / v), and magnetically stirred at 50-100℃ for 5-12 hours at atmospheric temperature; after surface modification, the mixture was diluted with deionized water and filtered through a membrane, then repeatedly washed with pure water to achieve a neutral pH value, and dried under vacuum at 50-100℃ for 12-36 hours. 2) Preparation of carbon nanotube solution: The carboxylated carbon nanotubes and dispersant from step 1) are dispersed in a solvent and ultrasonically cleaned for 1-3 hours to form a uniformly dispersed carbon nanotube solution. The mass ratio of carbon nanotubes to dispersant is 1:(0.1-0.3); the mass ratio of carbon nanotubes to solvent volume is (0.1mg-1mg):1ml; 3) Removing sizing agent from conductive fibers: Place the conductive fibers in an acetone solution and react at a constant temperature of 50-100℃ for 12-36 hours. Wash the fibers several times with anhydrous ethanol and deionized water alternately, and then dry the washed conductive fibers at 60-100℃ for 12-36 hours. 4) Preparation of electrophoresis solution: Add metal salt to the uniformly dispersed carbon nanotube solution prepared in step 2), sonicate for 0.5-1h, the metal ions will be adsorbed on the surface of carbon nanotubes, thus making the carbon nanotubes positively charged, and then centrifuge at 5000-10000r / min for 10-30min; take the supernatant as the electrophoresis solution. 5) Electrophoretic Deposition of Bone-like Porous Carbon Nanotube Layers: The bone-like porous carbon nanotube layer electrophoretic deposition system is a reaction generating device for depositing bone-like porous carbon nanotube layers on the surface of continuous conductive fiber bundles. It consists of an electrophoresis apparatus, an electrolytic cell, and a roller device. The roller device is placed in the electrolytic cell, and the continuous conductive fiber bundles pass through the roller and into the electrophoretic solution, through stainless steel electrode plates, and then out of the electrolytic cell via the roller. The stainless steel electrode plates with discontinuous structures in the electrolytic cell serve as the positive electrode and are connected to the positive electrode of the electrophoresis apparatus, with a discontinuity spacing of 50-300 μm. The conductive fibers serve as the negative electrode and are connected to the negative electrode of the electrophoresis apparatus, with a spacing of 1-2 cm between the two stainless steel electrode plates. The applied voltage is 10-30 V. Under the influence of an electric field... Under these conditions, carbon nanotubes that adsorb metal ions and carry a positive charge move towards the negatively charged electrode and are deposited on the surface of the conductive fiber. Due to the discontinuous structure of the stainless steel electrode plate, the area where the conductive fiber faces the stainless steel electrode plate has a faster deposition rate than other areas. Metal ions react with electrons and water to generate metal hydroxide, which acts as a binder to bond the conductive fiber and carbon nanotubes. Water on the surface of the conductive fiber is electrolyzed to generate hydrogen gas, which then escapes, completing the construction of the bone-like porous carbon nanotube layer. After a deposition time of 20-60 seconds, the conductive fiber with the bone-like porous carbon nanotube layer is repeatedly washed with ethanol and water for 1-3 minutes, respectively, to obtain the conductive fiber with the bone-like porous carbon nanotube layer.

2. The method according to claim 1, characterized in that: The dispersant in step 2) is N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP).

3. The method according to claim 1, characterized in that: In step 3), the conductive fiber is carbon fiber, polyacetylene fiber, or polyaniline fiber.

4. The method according to claim 1, characterized in that: In step 4), the metal salt is magnesium nitrate or magnesium chloride.

5. The method according to claim 1, characterized in that: In step 4), the mass ratio of metal salt to carbon nanotubes is 1:(0.1-0.5).

6. The method according to any one of claims 1-5, characterized in that, Includes the following steps: 1) Carboxylation of carbon nanotubes (CNTs): CNTs were immersed in a mixed solution of HNO3 / H2SO4 with a volume ratio of 1 / 3 and magnetically stirred at 50°C for 5 hours at atmospheric temperature to remove impurities and introduce carboxyl groups on the surface of CNTs. After surface modification, the mixture was diluted with deionized water and filtered through a membrane. Then it was repeatedly washed with pure water to achieve a neutral pH value and dried under vacuum at 50°C for 12 hours. 2) Preparation of carbon nanotube solution: 0.1g of carboxylated carbon nanotubes and 0.01g of N-methylpyrrolidone (NMP) from step 1) were dispersed in 1L of solvent and ultrasonically cleaned for 3h to form a uniformly dispersed carbon nanotube solution. 3) Removal of sizing agent from conductive fibers: The carbon fibers are placed in an acetone solution and reacted at a constant temperature of 50°C for 12 hours. They are then washed several times with alternating anhydrous ethanol and deionized water, and the washed carbon fibers are dried at 60°C for 12 hours. 4) Preparation of electrophoresis solution: Add 0.01g magnesium nitrate to the uniformly dispersed carbon nanotube solution prepared in step 2), sonicate for 0.5h, magnesium ions will be adsorbed on the surface of carbon nanotubes, thus making the carbon nanotubes positively charged, and then centrifuge at 5000r / min for 10min; take the supernatant as the electrophoresis solution. 5) Electrophoretic Deposition of Bone-like Porous Carbon Nanotube Layers: The bone-like porous carbon nanotube layer electrophoretic deposition system is a reaction generating device for depositing bone-like porous carbon nanotube layers on the surface of continuous conductive fiber bundles. It consists of an electrophoresis apparatus, an electrolytic cell, and a roller device. The roller device is placed in the electrolytic cell, and the continuous conductive fiber bundles pass through the roller and into the electrophoretic solution, through stainless steel electrode plates, and then out of the electrolytic cell via the roller. In the electrolytic cell, the stainless steel electrode plates with an intermittent structure are connected to the positive electrode of the electrophoresis apparatus as the positive electrode, with an intermittent spacing of 50 μm. The conductive fibers are connected to the negative electrode of the electrophoresis apparatus as the negative electrode, with a spacing of 1 cm between the two stainless steel electrode plates. The applied voltage is 10 V. Under the action of an electric field... Carbon nanotubes that adsorb metal ions and become positively charged will move towards the negatively charged electrode and be deposited on the surface of conductive fibers. Due to the discontinuous structure of the stainless steel electrode plate, the area where the conductive fiber faces the stainless steel electrode plate has a faster deposition rate than other areas. Metal ions react with electrons and water to generate metal hydroxide, which acts as a binder to bond the conductive fibers and carbon nanotubes. Water on the surface of the conductive fibers will electrolyze to generate hydrogen gas, which will then escape, completing the construction of the bone-like porous carbon nanotube layer. After a deposition time of 20 seconds, the conductive fiber with the bone-like porous carbon nanotube layer is repeatedly washed with ethanol and water for 1 minute each to obtain the conductive fiber with the bone-like porous carbon nanotube layer.

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