Coating modified carbon fiber with spider-like network structure as well as preparation method and application of coating modified carbon fiber

Abstract

The invention discloses a spider-like network structure coating modified carbon fiber as well as a preparation method and application thereof. The method comprises the following steps: 1, performing desizing treatment on carbon fiber; 2, preparing an aminated carbon nano tube; 3, preparing an aminated carbon nanotube dispersion liquid; and 4, uniformly laying the carbon fibers obtained in the step 1 on a filter membrane, carrying out vacuum filtration on the aminated carbon nanotube dispersion liquid, overturning the carbon fiber tows by 180 degrees, depositing the dispersion liquid, and drying to obtain the spider-like network structure coating modified carbon fibers. According to the invention, a netlike staggered structure coating composed of aminated carbon nanotubes is constructed on the surface of the carbon fiber, the modification technology is simple and easy to implement, the reaction condition is mild, and the method is environment-friendly and efficient. The modified carbon fiber prepared by the method can solve the problem of mutual exclusion of interface toughness of a composite material, the interface bonding strength of the composite material is improved by 46.4-78.0%, and the interface fracture toughness is improved by 94.6-176.0%.

Description

Technical Field

[0001] The present invention relates to the technical field of surface and interface modification and application of materials, and in particular to a carbon fiber modified with a spider web-like structure coating, and a preparation method and application thereof. Background Art

[0002] Carbon fiber reinforced resin-based composites have become key materials in modern industry, especially in aerospace, high-end sporting goods, automobiles, wind power generation and other fields due to their excellent comprehensive performance. Their core advantages and key challenges are closely centered around the interface. However, because carbon fiber undergoes high-temperature carbonization and graphitization during the preparation process, its surface is chemically inert and has low surface energy, making it difficult to fully infiltrate and contact with the resin matrix, resulting in low interface strength between it and the resin matrix. For this reason, improving the interface strength of composite materials by modifying the surface of carbon fiber has become one of the effective ways. However, improving the interface strength of composite materials will come at the expense of interface toughness, which is not conducive to the long-term, safe and stable application of composite materials. Summary of the Invention

[0003] The present invention aims to provide a carbon fiber modified with a spiderweb-like coating, its preparation method, and its application. A network-like, interlaced coating composed of amino-modified carbon nanotubes is constructed on the circumferential surface of the carbon fiber to simultaneously improve the composite's interfacial bonding strength and fracture toughness, resolving the interfacial strength-toughness trade-off. Furthermore, the method offers the advantages of simplicity, environmental friendliness, high efficiency, and low cost.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0006] Step 1: immersing the carbon fiber in an acetone solution, condensing and refluxing, washing with deionized water, and drying to obtain desized carbon fiber;

[0007] Step 2: Preparation of Aminated Carbon Nanotubes

[0008] Step 2.1, dispersing carbon nanotubes in concentrated acid at a mass ratio of 1:(5000-10000) and reflux-oxidizing under stirring, followed by centrifugation and washing with deionized water until the pH of the washing solution reaches 7, and freeze-drying to obtain carboxylated carbon nanotubes;

[0009] Step 2.2, mixing carboxylated carbon nanotubes with thionyl chloride and dimethylformamide in a mass ratio of 1:(1400-1800):(40-60), reflux under stirring, then centrifuging and washing with dichloromethane 3-5 times, and freeze-drying to obtain acyl chloride carbon nanotubes;

[0010] Step 2.3, adding the chlorinated carbon nanotubes to an organic solvent containing an organic amine polymer and subjecting the mixture to reflux treatment under stirring, wherein the mass ratio of the chlorinated carbon nanotubes to the organic amine polymer and the organic solvent is 1:1:(40-80), followed by centrifugation and washing with deionized water 3-5 times, and freeze-drying to obtain the amino-treated carbon nanotubes;

[0011] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0012] Dispersing the amino-modified carbon nanotubes prepared in step 2 in an organic solvent, and uniformly dispersing by ultrasonication at 0-10° C. to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 0.5% to 2%;

[0013] Step 4: Modification of carbon fiber surface coating with spider web structure

[0014] The desized carbon fiber tow obtained in step 1 is evenly laid on the filter membrane, and the amino-treated carbon nanotube dispersion is vacuum filtered and coated on the surface of the desized carbon fiber. After the desized carbon fiber tow is turned 180°, the vacuum filtration and coating steps are repeated. After drying, a carbon fiber modified with a spider web-like structure coating is obtained.

[0015] Furthermore, in step 1, the condensation reflux temperature is 80-100° C., the time is 12-96 hours, and the drying temperature is 60-80° C., the time is 2-4 hours.

[0016] Furthermore, in step 2, the stirring speed is 20 to 40 rpm, the centrifugal speed is 5000 to 10000 rpm, the freezing temperature is -50 to -10°C, and the freezing time is 12 to 48 hours;

[0017] The concentrated acid in step 2.1 is concentrated nitric acid, concentrated sulfuric acid or a mixture of the two, the oxidation reflux temperature is 70-90°C, and the reaction time is 3-6h;

[0018] The reflux temperature in step 2.2 is 60-80°C, and the reaction time is 12-48h;

[0019] In step 2.3, the organic amine polymer is selected from the group consisting of polyetheramine, polyetherimide, polydopamine, polyamide-amine dendrimer, polyethyleneimine, and aminosilane coupling agents; the organic solvent is selected from the group consisting of tetrahydrofuran, dimethylformamide, ethanol, and dichloromethane; the reflux temperature is 80-100° C.; and the reaction time is 12-48 hours.

[0020] Furthermore, in step 3, the organic solvent is one of tetrahydrofuran, dimethylformamide, ethanol or dichloromethane, and the ultrasonic dispersion time is 2 to 4 hours.

[0021] Furthermore, in the step 4, the vacuum filtration is carried out according to the ratio of the volume (ml) of the amino-treated carbon nanotube dispersion to the diameter (cm) of the filter membrane (1-2):1.

[0022] Furthermore, in step 4, the drying temperature is 60-80° C. and the drying time is 2-4 hours.

[0023] The present invention also provides a carbon fiber modified by a coating having a spider web structure, wherein the surface of the carbon fiber is evenly covered with a coating having a network-like staggered structure of amino-treated carbon nanotubes.

[0024] The present invention also provides an application of carbon fibers modified by a spider web-like structure coating in solving the problem of strength-toughness mutual exclusion at the interface of composite materials.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention uses carbon nanotubes to construct an interlaced network structure on the fiber surface, and constructs a mesh-like interlaced structure coating composed of amino carbon nanotubes on the circumferential surface of the carbon fiber to simultaneously improve the interfacial bonding strength and fracture toughness of the composite material, solving the problem of interfacial strength-toughness mutual exclusion. The reinforcing mechanism of the present invention to improve the interfacial bonding strength of the composite material is as follows: the network structure formed by the amino carbon nanotubes can improve the wettability of the resin to the fiber through capillary action, promote the covalent and hydrogen bonding between the active amino groups and the fiber surface and the epoxy resin, and is conducive to the transmission of interfacial stress and improve the interfacial bonding strength of the composite material. The toughening mechanism of the present invention to improve the interfacial fracture toughness of the composite material is as follows: under the action of shear force, the network structure formed by the amino carbon nanotubes consumes energy through hydrogen bonding / van der Waals force sliding. In addition, the extraction of the carbon nanotubes from the resin can also consume energy, improving the interfacial fracture toughness.

[0027] The preparation method of the present invention is simple and easy, has mild reaction conditions, is pollution-free, environmentally friendly and highly efficient. The prepared modified carbon fiber can simultaneously improve the interfacial bonding strength and interfacial fracture toughness of the composite material, with the interfacial bonding strength increased by 46.4-78.0% and the interfacial fracture toughness increased by 94.6-176.0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a surface morphology of the spider-web structure coating modified carbon fiber prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Example 1:

[0031] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0032] Step 1: immersing the carbon fiber in an acetone solution at 80° C. and refluxing for 48 hours, then washing with deionized water, and drying in a drying oven at 60° C. for 3 hours to obtain desized carbon fiber;

[0033] Step 2: Preparation of Aminated Carbon Nanotubes

[0034] Step 2.1, dispersing carbon nanotubes in a mixture of concentrated nitric acid and concentrated sulfuric acid (volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1) at a mass ratio of 1:7500, and oxidizing and refluxing at 80°C for 4 h with continuous stirring at a stirring speed of 20 rpm. After the reaction, centrifuging at 9000 rpm and washing with deionized water until the pH of the washing solution reaches 7, and freeze-drying at -50°C for 24 h to obtain carboxylated carbon nanotubes;

[0035] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1600:50, and refluxed at 60°C for 48 h with continuous stirring at 20 rpm. After the reaction, the mixture was centrifuged at 9000 rpm and washed with dichloromethane three times, and freeze-dried at -50°C for 24 h to obtain chlorinated carbon nanotubes;

[0036] Step 2.3, adding the chlorinated carbon nanotubes to dimethylformamide containing polyetherimide and reflux at 80°C for 48 hours, wherein the mass ratio of the chlorinated carbon nanotubes to the polyetherimide and dimethylformamide is 1:1:60, and stirring is continued during the reaction at a stirring speed of 20 rpm. After the reaction is completed, centrifugation is performed at 9000 rpm and the mixture is washed with deionized water three times, and freeze-dried at -50°C for 24 hours to obtain the amino-modified carbon nanotubes;

[0037] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0038] Dispersing the amino carbon nanotubes prepared in step 2 in dimethylformamide, and ultrasonically dispersing at 0°C for 3 hours to obtain an amino carbon nanotube dispersion with a mass fraction of 1%;

[0039] Step 4: Modification of carbon fiber surface coating with spider web structure

[0040] The desized carbon fiber tow obtained in step 1 was evenly laid on a filter membrane, and the amination-treated carbon nanotube dispersion was vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the amination-treated carbon nanotube dispersion: the diameter (cm) of the filter membrane = 1.57:1; after the desized carbon fiber tow was flipped 180°, the vacuum filtration and coating steps were repeated, and after drying at 60°C for 3h, a spider-web-like structure-modified carbon fiber coating was obtained.

[0041] The surface morphology of the carbon fiber modified by the spider web structure coating prepared in this embodiment is as follows: Figure 1 As shown, from Figure 1 It can be seen that the amino CNTs form a grid structure on the fiber surface, and the coating is evenly distributed. The modified carbon fiber epoxy composite prepared using this example has an interfacial shear strength that is 78.0% higher than that of the desized carbon fiber epoxy composite, and an interfacial fracture toughness that is 176.0% higher.

[0042] Example 2:

[0043] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0044] Step 1: immersing the carbon fiber in a 100° C. acetone solution and condensing and refluxing for 12 hours, then washing with deionized water, and drying in a drying oven at 80° C. for 2 hours to obtain desized carbon fiber;

[0045] Step 2: Preparation of Aminated Carbon Nanotubes

[0046] Step 2.1, dispersing carbon nanotubes in concentrated nitric acid at a mass ratio of 1:10,000 and oxidizing under reflux at 90°C for 3 h with continuous stirring at a stirring speed of 40 rpm. After the reaction, centrifuging at 10,000 rpm and washing with deionized water until the pH of the washing solution reached 7, and freeze-drying at -10°C for 48 h to obtain carboxylated carbon nanotubes;

[0047] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1800:60, and refluxed at 80°C for 12 h with continuous stirring at 40 rpm. After the reaction, the mixture was centrifuged at 10,000 rpm and washed with dichloromethane five times, and freeze-dried at -10°C for 48 h to obtain acyl chloride carbon nanotubes;

[0048] Step 2.3, adding the chlorinated carbon nanotubes to tetrahydrofuran containing polyetherimide and reflux at 100°C for 12 hours, wherein the mass ratio of the chlorinated carbon nanotubes to the polyetherimide and tetrahydrofuran is 1:1:80, and stirring is continued during the reaction at a stirring speed of 40 rpm. After the reaction is completed, centrifugation is performed at 10,000 rpm and the mixture is washed with deionized water five times, and freeze-dried at -10°C for 48 hours to obtain the amino-modified carbon nanotubes;

[0049] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0050] The amino-modified carbon nanotubes prepared in step 2 were dispersed in tetrahydrofuran, and ultrasonically dispersed at 0°C for 3 h to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 1%;

[0051] Step 4: Modification of carbon fiber surface coating with spider web structure

[0052] The desized carbon fiber tow obtained in step 1 is evenly laid on the filter membrane, and the amination-treated carbon nanotube dispersion is vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the amination-treated carbon nanotube dispersion: the diameter (cm) of the filter membrane = 1:1; after the desized carbon fiber tow is turned 180°, the above vacuum filtration and coating steps are repeated, and after drying at 80°C for 2h, a spider-web-like structure-modified carbon fiber coating is obtained.

[0053] The modified carbon fiber epoxy composite material prepared in this embodiment has an interface shear strength increased by 46.4% and an interface fracture toughness increased by 94.6% compared to the desized carbon fiber epoxy composite material.

[0054] Example 3:

[0055] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0056] Step 1: immersing the carbon fiber in a 90° C. acetone solution, condensing and refluxing for 24 hours, washing with deionized water, and drying in a drying oven at 70° C. for 4 hours to obtain desized carbon fiber;

[0057] Step 2: Preparation of Aminated Carbon Nanotubes

[0058] Step 2.1, dispersing carbon nanotubes in concentrated sulfuric acid at a mass ratio of 1:5000 and oxidizing under reflux at 70°C for 6 h with continuous stirring at a stirring speed of 30 rpm. After the reaction, centrifuging at 5000 rpm and washing with deionized water until the pH of the washing solution reached 7, and freeze-drying at -30°C for 12 h to obtain carboxylated carbon nanotubes;

[0059] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1400:40, and refluxed at 70°C for 24 h with continuous stirring at 30 rpm. After the reaction, the mixture was centrifuged at 5000 rpm and washed with dichloromethane four times, and freeze-dried at -30°C for 12 h to obtain chlorinated carbon nanotubes;

[0060] Step 2.3, adding the chlorinated carbon nanotubes to ethanol containing polyetherimide and reflux at 90°C for 24 hours, wherein the mass ratio of the chlorinated carbon nanotubes to the polyetherimide and ethanol is 1:1:40, and stirring is continued during the reaction at a stirring speed of 30 rpm. After the reaction is completed, centrifugation is performed at 5000 rpm and the mixture is washed with deionized water four times, and freeze-dried at -30°C for 12 hours to obtain the amino-modified carbon nanotubes;

[0061] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0062] The amino-modified carbon nanotubes prepared in step 2 were dispersed in ethanol and ultrasonically dispersed at 5° C. for 2 h to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 0.5%;

[0063] Step 4: Modification of carbon fiber surface coating with spider web structure

[0064] The desized carbon fiber tow obtained in step 1 was evenly laid on a filter membrane, and the aminated carbon nanotube dispersion was vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the aminated carbon nanotube dispersion: the diameter (cm) of the filter membrane = 1.45:1; after the desized carbon fiber tow was turned 180°, the vacuum filtration and coating steps were repeated, and after drying at 70°C for 4 hours, a spider web-like structured coating-modified carbon fiber was obtained.

[0065] The modified carbon fiber epoxy composite material prepared in this embodiment has an interface shear strength increased by 57.7% and an interface fracture toughness increased by 123.4% compared to the desized carbon fiber epoxy composite material.

[0066] Example 4:

[0067] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0068] Step 1: immersing the carbon fiber in an acetone solution at 80° C. and refluxing for 96 hours, then washing with deionized water, and drying in a drying oven at 60° C. for 4 hours to obtain desized carbon fiber;

[0069] Step 2: Preparation of Aminated Carbon Nanotubes

[0070] Step 2.1, dispersing carbon nanotubes in concentrated nitric acid at a mass ratio of 1:7000 and refluxing at 80°C for 4 h with continuous stirring at a stirring speed of 30 rpm. After the reaction, centrifuging at 8000 rpm and washing with deionized water until the pH of the washing solution reached 7, followed by freeze-drying at -50°C for 12 h to obtain carboxylated carbon nanotubes;

[0071] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1500:45, and refluxed at 75°C for 36 h with continuous stirring at 30 rpm. After the reaction, the mixture was centrifuged at 8000 rpm and washed with dichloromethane four times, and freeze-dried at -50°C for 12 h to obtain acyl chloride carbon nanotubes;

[0072] Step 2.3, adding the chlorinated carbon nanotubes to dichloromethane containing polyetherimide and reflux at 85°C for 36 hours, wherein the mass ratio of the chlorinated carbon nanotubes to polyetherimide and dichloromethane is 1:1:65, and stirring is continued during the reaction at a stirring speed of 30 rpm. After the reaction is completed, centrifugation is performed at 8000 rpm and the mixture is washed with deionized water four times, and freeze-dried at -50°C for 12 hours to obtain the amino-modified carbon nanotubes;

[0073] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0074] The amino-modified carbon nanotubes prepared in step 2 were dispersed in dichloromethane and ultrasonically dispersed at 0°C for 3 h to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 1.5%;

[0075] Step 4: Modification of carbon fiber surface coating with spider web structure

[0076] The desized carbon fiber tow obtained in step 1 was evenly laid on a filter membrane, and the aminated carbon nanotube dispersion was vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the aminated carbon nanotube dispersion: the diameter (cm) of the filter membrane = 1.78:1; after the desized carbon fiber tow was turned 180°, the vacuum filtration and coating steps were repeated, and after drying at 60°C for 4 hours, a spider-web-like structure-modified carbon fiber coating was obtained.

[0077] The modified carbon fiber epoxy composite material prepared in this embodiment has an interface shear strength increased by 69.6% and an interface fracture toughness increased by 144.5% compared to the desized carbon fiber epoxy composite material.

[0078] Example 5:

[0079] A carbon fiber modified by coating with a spider web-like structure, comprising the following steps:

[0080] Step 1: immersing the carbon fiber in an acetone solution at 80° C. and refluxing for 96 hours, then washing with deionized water, and drying in a drying oven at 60° C. for 4 hours to obtain desized carbon fiber;

[0081] Step 2: Preparation of Aminated Carbon Nanotubes

[0082] Step 2.1, dispersing carbon nanotubes in concentrated nitric acid at a mass ratio of 1:7000 and refluxing at 80°C for 4 h with continuous stirring at a stirring speed of 30 rpm. After the reaction, centrifuging at 8000 rpm and washing with deionized water until the pH of the washing solution reached 7, followed by freeze-drying at -50°C for 12 h to obtain carboxylated carbon nanotubes;

[0083] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1500:45, and refluxed at 75°C for 36 h with continuous stirring at 30 rpm. After the reaction, the mixture was centrifuged at 8000 rpm and washed with dichloromethane four times, and freeze-dried at -50°C for 12 h to obtain acyl chloride carbon nanotubes;

[0084] Step 2.3, adding the chlorinated carbon nanotubes to dichloromethane containing polyetheramine and refluxing at 85°C for 36 hours, wherein the mass ratio of the chlorinated carbon nanotubes to the polyetheramine and dichloromethane is 1:1:65, stirring continuously during the reaction at a stirring speed of 30 rpm. After the reaction is completed, centrifugation at 8000 rpm and washing with deionized water four times, and freeze-drying at -50°C for 12 hours to obtain the amino-modified carbon nanotubes;

[0085] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0086] The amino-modified carbon nanotubes prepared in step 2 were dispersed in dichloromethane and ultrasonically dispersed at 10° C. for 4 h to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 2%;

[0087] Step 4: Modification of carbon fiber surface coating with spider web structure

[0088] The desized carbon fiber tow obtained in step 1 is evenly laid on the filter membrane, and the aminated carbon nanotube dispersion is vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the aminated carbon nanotube dispersion: the diameter (cm) of the filter membrane is 2:1; after the desized carbon fiber tow is turned 180°, the above vacuum filtration and coating steps are repeated, and after drying at 60°C for 4 hours, a spider web structure-like coating-modified carbon fiber is obtained.

[0089] Example 6:

[0090] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0091] Step 1: immersing the carbon fiber in an acetone solution at 80° C. and refluxing for 96 hours, then washing with deionized water, and drying in a drying oven at 60° C. for 4 hours to obtain desized carbon fiber;

[0092] Step 2: Preparation of Aminated Carbon Nanotubes

[0093] Step 2.1, dispersing carbon nanotubes in concentrated nitric acid at a mass ratio of 1:7000 and refluxing at 80°C for 4 h with continuous stirring at a stirring speed of 30 rpm. After the reaction, centrifuging at 8000 rpm and washing with deionized water until the pH of the washing solution reached 7, followed by freeze-drying at -50°C for 12 h to obtain carboxylated carbon nanotubes;

[0094] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1500:45, and refluxed at 75°C for 36 h with continuous stirring at 30 rpm. After the reaction, the mixture was centrifuged at 8000 rpm and washed with dichloromethane four times, and freeze-dried at -50°C for 12 h to obtain acyl chloride carbon nanotubes;

[0095] Step 2.3, adding the chlorinated carbon nanotubes to ethanol containing polydopamine and reflux at 85°C for 36 hours, wherein the mass ratio of the chlorinated carbon nanotubes to polydopamine and ethanol is 1:1:65, and stirring is continued during the reaction at a stirring speed of 30 rpm. After the reaction is completed, centrifugation is performed at 8000 rpm and the mixture is washed with deionized water four times, and freeze-dried at -50°C for 12 hours to obtain the amino-modified carbon nanotubes;

[0096] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0097] The amino-modified carbon nanotubes prepared in step 2 were dispersed in ethanol and ultrasonically dispersed at 10° C. for 4 h to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 2%;

[0098] Step 4: Modification of carbon fiber surface coating with spider web structure

[0099] The desized carbon fiber tow obtained in step 1 is evenly laid on the filter membrane, and the aminated carbon nanotube dispersion is vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the aminated carbon nanotube dispersion: the diameter (cm) of the filter membrane is 2:1; after the desized carbon fiber tow is turned 180°, the above vacuum filtration and coating steps are repeated, and after drying at 60°C for 4 hours, a spider web structure-like coating-modified carbon fiber is obtained.

[0100] Example 7:

[0101] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0102] Step 1: immersing the carbon fiber in an acetone solution at 80° C. and refluxing for 96 hours, then washing with deionized water, and drying in a drying oven at 60° C. for 4 hours to obtain desized carbon fiber;

[0103] Step 2: Preparation of Aminated Carbon Nanotubes

[0104] Step 2.1, dispersing carbon nanotubes in concentrated nitric acid at a mass ratio of 1:7000 and refluxing at 80°C for 4 h with continuous stirring at a stirring speed of 30 rpm. After the reaction, centrifuging at 8000 rpm and washing with deionized water until the pH of the washing solution reached 7, followed by freeze-drying at -50°C for 12 h to obtain carboxylated carbon nanotubes;

[0105] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1500:45, and refluxed at 75°C for 36 h with continuous stirring at 30 rpm. After the reaction, the mixture was centrifuged at 8000 rpm and washed with dichloromethane four times, and freeze-dried at -50°C for 12 h to obtain acyl chloride carbon nanotubes;

[0106] Step 2.3, adding chlorinated carbon nanotubes to ethanol containing polyamide-amine dendrimers and reflux at 85°C for 36 hours, wherein the mass ratio of chlorinated carbon nanotubes to polyamide-amine dendrimers to ethanol is 1:1:65, and stirring is continued during the reaction at a stirring speed of 30 rpm. After the reaction is completed, centrifugation is performed at 8000 rpm and the mixture is washed with deionized water four times, and freeze-dried at -50°C for 12 hours to obtain amino-modified carbon nanotubes;

[0107] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0108] The amino-modified carbon nanotubes prepared in step 2 were dispersed in ethanol and ultrasonically dispersed at 10° C. for 4 h to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 2%;

[0109] Step 4: Modification of carbon fiber surface coating with spider web structure

[0110] The desized carbon fiber tow obtained in step 1 is evenly laid on the filter membrane, and the aminated carbon nanotube dispersion is vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the aminated carbon nanotube dispersion: the diameter (cm) of the filter membrane is 2:1; after the desized carbon fiber tow is turned 180°, the above vacuum filtration and coating steps are repeated, and after drying at 60°C for 4 hours, a spider web structure-like coating-modified carbon fiber is obtained.

[0111] Example 8:

[0112] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0113] Step 1: immersing the carbon fiber in an acetone solution at 80° C. and refluxing for 96 hours, then washing with deionized water, and drying in a drying oven at 60° C. for 4 hours to obtain desized carbon fiber;

[0114] Step 2: Preparation of Aminated Carbon Nanotubes

[0115] Step 2.1, dispersing carbon nanotubes in concentrated nitric acid at a mass ratio of 1:7000 and refluxing at 80°C for 4 h with continuous stirring at a stirring speed of 30 rpm. After the reaction, centrifuging at 8000 rpm and washing with deionized water until the pH of the washing solution reached 7, followed by freeze-drying at -50°C for 12 h to obtain carboxylated carbon nanotubes;

[0116] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1500:45, and refluxed at 75°C for 36 h with continuous stirring at 30 rpm. After the reaction, the mixture was centrifuged at 8000 rpm and washed with dichloromethane four times, and freeze-dried at -50°C for 12 h to obtain acyl chloride carbon nanotubes;

[0117] Step 2.3, adding the chlorinated carbon nanotubes to polyethyleneimine in ethanol and refluxing at 85°C for 36 hours, wherein the mass ratio of the chlorinated carbon nanotubes to polyethyleneimine and ethanol is 1:1:65, and stirring is continued during the reaction at a stirring speed of 30 rpm. After the reaction is completed, centrifugation is performed at 8000 rpm and the mixture is washed with deionized water four times, and freeze-dried at -50°C for 12 hours to obtain the amino-modified carbon nanotubes;

[0118] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0119] The amino-modified carbon nanotubes prepared in step 2 were dispersed in ethanol and ultrasonically dispersed at 10° C. for 4 h to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 2%;

[0120] Step 4: Modification of carbon fiber surface coating with spider web structure

[0121] The desized carbon fiber tow obtained in step 1 is evenly laid on the filter membrane, and the aminated carbon nanotube dispersion is vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the aminated carbon nanotube dispersion: the diameter (cm) of the filter membrane is 2:1; after the desized carbon fiber tow is turned 180°, the above vacuum filtration and coating steps are repeated, and after drying at 60°C for 4 hours, a spider web structure-like coating-modified carbon fiber is obtained.

[0122] Example 9:

[0123] A method for preparing carbon fiber modified by a spider web-like structure coating comprises the following steps:

[0124] Step 1: immersing the carbon fiber in an acetone solution at 80° C. and refluxing for 96 hours, then washing with deionized water, and drying in a drying oven at 60° C. for 4 hours to obtain desized carbon fiber;

[0125] Step 2: Preparation of Aminated Carbon Nanotubes

[0126] Step 2.1, dispersing carbon nanotubes in concentrated nitric acid at a mass ratio of 1:7000 and refluxing at 80°C for 4 h with continuous stirring at a stirring speed of 30 rpm. After the reaction, centrifuging at 8000 rpm and washing with deionized water until the pH of the washing solution reached 7, followed by freeze-drying at -50°C for 12 h to obtain carboxylated carbon nanotubes;

[0127] Step 2.2, carboxylated carbon nanotubes were mixed with thionyl chloride and dimethylformamide in a mass ratio of 1:1500:45, and refluxed at 75°C for 36 h with continuous stirring at 30 rpm. After the reaction, the mixture was centrifuged at 8000 rpm and washed with dichloromethane four times, and freeze-dried at -50°C for 12 h to obtain acyl chloride carbon nanotubes;

[0128] Step 2.3, adding the chlorinated carbon nanotubes to ethanol containing an aminosilane coupling agent and refluxing at 85°C for 36 hours, wherein the mass ratio of the chlorinated carbon nanotubes to the aminosilane coupling agent and the ethanol is 1:1:65, and stirring is continued during the reaction at a stirring speed of 30 rpm. After the reaction is completed, centrifugation is performed at 8000 rpm and the mixture is washed with deionized water four times, and freeze-dried at -50°C for 12 hours to obtain the amino-treated carbon nanotubes;

[0129] Step 3: Prepare the dispersion of amino-modified carbon nanotubes

[0130] The amino-modified carbon nanotubes prepared in step 2 were dispersed in ethanol and ultrasonically dispersed at 10° C. for 4 h to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 2%;

[0131] Step 4: Modification of carbon fiber surface coating with spider web structure

[0132] The desized carbon fiber tow obtained in step 1 is evenly laid on the filter membrane, and the aminated carbon nanotube dispersion is vacuum filtered and coated on the surface of the desized carbon fiber, wherein the volume (ml) of the aminated carbon nanotube dispersion: the diameter (cm) of the filter membrane is 2:1; after the desized carbon fiber tow is turned 180°, the above vacuum filtration and coating steps are repeated, and after drying at 60°C for 4 hours, a spider web structure-like coating-modified carbon fiber is obtained.

Claims

1. A method for preparing carbon fiber modified by a spider web structure coating, characterized in that: The steps include: Step 1: immersing the carbon fiber in an acetone solution, condensing and refluxing, washing with deionized water, and drying to obtain desized carbon fiber; Step 2: Preparation of Aminated Carbon Nanotubes Step 2.1, dispersing carbon nanotubes in concentrated acid at a mass ratio of 1:(5000-10000) and reflux-oxidizing under stirring, followed by centrifugation and washing with deionized water until the pH of the washing solution reaches 7, and freeze-drying to obtain carboxylated carbon nanotubes; Step 2.2, mixing carboxylated carbon nanotubes with thionyl chloride and dimethylformamide in a mass ratio of 1:(1400-1800):(40-60), reflux under stirring, then centrifuging and washing with dichloromethane 3-5 times, and freeze-drying to obtain acyl chloride carbon nanotubes; Step 2.3, adding the chlorinated carbon nanotubes to an organic solvent containing an organic amine polymer and subjecting the mixture to reflux treatment under stirring, wherein the mass ratio of the chlorinated carbon nanotubes to the organic amine polymer and the organic solvent is 1:1:(40-80), followed by centrifugation and washing with deionized water 3-5 times, and freeze-drying to obtain the amino-treated carbon nanotubes; Step 3: Prepare the dispersion of amino-modified carbon nanotubes Dispersing the amino-modified carbon nanotubes prepared in step 2 in an organic solvent, and uniformly dispersing by ultrasonication at 0-10° C. to obtain an amino-modified carbon nanotube dispersion with a mass fraction of 0.5% to 2%; Step 4: Modification of carbon fiber surface coating with spider web structure The desized carbon fiber tow obtained in step 1 is evenly laid on the filter membrane, and the amino-treated carbon nanotube dispersion is vacuum filtered and coated on the surface of the desized carbon fiber. After the desized carbon fiber tow is turned 180°, the vacuum filtration and coating steps are repeated. After drying, a carbon fiber modified with a spider web-like structure coating is obtained.

2. The method for preparing a carbon fiber modified with a spider web structure coating according to claim 1, characterized in that: In the step 1, the condensation reflux temperature is 80-100° C., the time is 12-96 hours, and the drying temperature is 60-80° C., the time is 2-4 hours.

3. The method for preparing a carbon fiber modified with a spider web structure coating according to claim 1, characterized in that: In step 2, the stirring speed is 20 to 40 rpm, the centrifugal speed is 5000 to 10000 rpm, the freezing temperature is -50 to -10°C, and the freezing time is 12 to 48 hours; The concentrated acid in step 2.1 is concentrated nitric acid, concentrated sulfuric acid or a mixture of the two, the oxidation reflux temperature is 70-90°C, and the reaction time is 3-6h; The reflux temperature in step 2.2 is 60-80°C, and the reaction time is 12-48h; In step 2.3, the organic amine polymer is selected from the group consisting of polyetheramine, polyetherimide, polydopamine, polyamide-amine dendrimer, polyethyleneimine, and aminosilane coupling agents; the organic solvent is selected from the group consisting of tetrahydrofuran, dimethylformamide, ethanol, and dichloromethane; the reflux temperature is 80-100° C.; and the reaction time is 12-48 hours.

4. The method for preparing a carbon fiber modified with a spider web structure coating according to claim 1, characterized in that: In step 3, the organic solvent is one of tetrahydrofuran, dimethylformamide, ethanol or dichloromethane, and the ultrasonic dispersion time is 2 to 4 hours.

5. The method for preparing a carbon fiber modified with a spider web structure coating according to claim 1, characterized in that: In the step 4, the vacuum filtration is carried out according to the ratio of the volume (ml) of the amino-treated carbon nanotube dispersion to the diameter (cm) of the filter membrane (1-2):

1.

6. The method for preparing a carbon fiber modified with a spider web structure coating according to claim 1, characterized in that: In step 4, the drying temperature is 60-80° C. and the drying time is 2-4 hours.

7. A spider web structure-modified carbon fiber prepared by the method according to any one of claims 1 to 6, characterized in that: The surface of the carbon fiber is evenly covered with a coating layer having a network-like staggered structure of amino-treated carbon nanotubes.

8. Use of the spider-web-like structure coating modified carbon fiber according to claim 7 in solving the problem of strength-toughness mutual exclusion at the interface of composite materials.

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