A nanofiber yarn-coated carbon fiber bundle composite filament and its preparation method

Abstract

This invention relates to the field of carbon fiber composite materials technology, and discloses a carbon fiber bundle composite filament coated with nanofiber yarn, comprising carbon fiber bundles and nanofiber yarn, wherein the nanofiber yarn coats the outer surface of the carbon fiber bundles; the carbon fiber bundles are high-modulus carbon fiber bundles, and the nanofiber yarn is prepared from polymer materials by conjugated electrospinning. This invention utilizes conjugated electrospinning technology to introduce a dense and uniformly distributed layer of nanofiber yarn onto the surface of high-modulus carbon fiber bundles, obtaining a carbon fiber bundle composite filament coated with nanofiber yarn. This composite filament exhibits good wear resistance and toughness, and its processability is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber composite materials technology, and in particular to a carbon fiber bundle composite filament coated with nanofiber yarn and its preparation method. Background Technology

[0002] High-modulus carbon fiber (HMCF) possesses a specific modulus 5-7 times greater than aluminum alloys and a lower mass density than metallic materials. Its reinforced composites can achieve zero expansion in alternating temperature environments, exhibiting lightweight, high stiffness, and dimensional stability, thus finding wide application in aerospace vehicles, deep space exploration, and other fields. However, current HMCF production processes include a 3000℃ high-temperature graphitization process. This results in a denser arrangement of graphite crystal layers parallel to the fiber axis, and its surface structure more closely resembles a three-dimensional ordered graphite structure. This leads to extremely high surface inertness and numerous fibrous strands, resulting in poor fiber weaving properties and a high susceptibility to breakage during processing. Therefore, improving the weaving properties of high-modulus carbon fiber is a pressing issue that needs to be addressed. Summary of the Invention

[0003] In view of this, the present invention provides a carbon fiber bundle composite filament coated with nanofiber yarn and its preparation method, so as to solve the problems of poor weaving performance and easy breakage during processing of high modulus carbon fiber.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] On one hand, the present invention provides a carbon fiber bundle composite filament covered with nanofiber yarn, comprising carbon fiber bundles and nanofiber yarn, wherein the nanofiber yarn covers the outer surface of the carbon fiber bundles;

[0006] The carbon fiber bundle is a high-modulus carbon fiber bundle, and the nanofiber yarn is prepared from polymer material by conjugated electrospinning.

[0007] Preferably, the carbon fiber bundle consists of 1,000-36,000 high-modulus carbon fiber filaments, and the diameter of a single high-modulus carbon fiber filament is 5-7 μm.

[0008] Preferably, the high-modulus carbon fiber filament has a carbon content ≥99%, a tensile strength ≥3200MPa, a tensile modulus ≥350GPa, and a bulk density of 1.81-1.83g / cm³. 3 .

[0009] Preferably, the coating thickness of the nanofiber yarn is 10-30 μm.

[0010] Preferably, the average diameter of the nanofiber yarn is 50-800 nm.

[0011] Preferably, the polymer material includes one or more of silk fibroin, polyvinylidene fluoride, polyimide, nanocellulose, aramid, and aramid sulfone.

[0012] On the other hand, the present invention provides a method for preparing a carbon fiber bundle composite filament coated with nanofiber yarn, comprising the following steps:

[0013] (1) The polymer material is mixed with an organic solvent to obtain an electrospinning solution;

[0014] (2) Fix the carbon fiber bundle to the take-up turntable of the electrospinning machine, and then spray the electrospinning liquid onto the surface of the carbon fiber bundle to form nanofiber yarn, thereby obtaining carbon fiber bundle composite filament material covered with nanofiber yarn.

[0015] Preferably, the mass percentage concentration of the electrospinning solution is 5-20%.

[0016] Preferably, the organic solvent includes one or more of N,N-dimethylformamide, dichloromethane, formic acid, tetrahydrofuran, and methylpyrrolidone.

[0017] Preferably, the moving speed of the carbon fiber bundle is 2-10 mm / s.

[0018] Preferably, the distance between the spinning needle of the electrospinning machine and the take-up turntable is 6-10 cm.

[0019] Preferably, the rotation speed of the take-up turntable is 200-1000 rpm.

[0020] Preferably, the propulsion speed of the electrospinning solution is 0.2-3 mL / h.

[0021] Preferably, the distance between the positive and negative spinning needles of the electrospinning machine is 9-15 cm.

[0022] Preferably, the electrospinning solutions sprayed from the positive and negative spinning needles of the electrospinning machine are the same or different.

[0023] Preferably, the positive electrode voltage of the electrospinning machine is 4-20kV, and the negative electrode voltage is -4 to -20kV.

[0024] This invention provides a carbon fiber bundle composite filament coated with nanofiber yarn and its preparation method. Compared with the prior art, its advantages are as follows:

[0025] This invention utilizes conjugate electrospinning technology to introduce a dense and uniformly distributed layer of nanofiber yarn onto the surface of high-modulus carbon fiber bundles, resulting in a carbon fiber bundle composite filament coated with nanofiber yarn. This composite filament exhibits excellent wear resistance and toughness, thereby improving its weaving performance and significantly enhancing its processability. Furthermore, the surface of the carbon fiber bundle composite filament coated with nanofiber yarn of this invention contains numerous pores, which can effectively improve permeability. Additionally, the nanofiber yarn can provide a certain degree of support and buffer stress transmission, which is beneficial for strengthening the interface of the composite filament. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the electrospinning process of the present invention;

[0028] Figure 2 This is a scanning electron microscope image of the surface of the carbon fiber bundle composite filament coated with nanofiber yarn prepared in Example 1.

[0029] Figure 3 This is a scanning electron microscope image of the cross-section of the carbon fiber bundle composite filament coated with nanofiber yarn prepared in Example 1.

[0030] Figure 4 The images show scanning electron microscope (SEM) images of the cross-section (right image) and longitudinal section (left image) of the second sample to be tested.

[0031] Figure 5 The images show the carbon fiber bundle composite filaments coated with nanofiber yarn prepared in Example 8 and the carbon fiber bundle knotting test results in Comparative Example 1. Detailed Implementation

[0032] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the later embodiments, conditions and methods known in the art can be used for processing.

[0033] In one aspect of the present invention, a carbon fiber bundle composite filament coated with nanofiber yarn is provided, comprising carbon fiber bundles and nanofiber yarn, wherein the nanofiber yarn coats the outer surface of the carbon fiber bundles; the carbon fiber bundles are high-modulus carbon fiber bundles, and the nanofiber yarn is prepared from polymer materials by conjugated electrospinning.

[0034] In some embodiments of the present invention, the carbon fiber bundle is composed of 1,000-36,000 high-modulus carbon fiber filaments, that is, the specification of the carbon fiber bundle is 1-36K, for example, it can be 1K, 5K, 10K, 15K, 20K, 25K, 30K, 36K, etc.; the diameter of a single high-modulus carbon fiber filament is 5-7μm, for example, it can be 5μm, 5.5μm, 6μm, 6.5μm, 7μm, etc.

[0035] In some embodiments of the present invention, the high-modulus carbon fiber filament has a carbon content ≥99%, a tensile strength ≥3200MPa, a tensile modulus ≥350GPa, and a bulk density of 1.81-1.83g / cm³. 3 Specifically, high-modulus carbon fibers can be, for example, polyacrylonitrile-based carbon fibers, and more specifically, BHM3 carbon fibers.

[0036] In some embodiments of the present invention, the coating thickness of the nanofiber yarn is 10-30 μm, for example, it can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.; the average diameter of the nanofiber yarn is 50-800 nm, for example, it can be 50 nm, 100 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, etc.

[0037] In some embodiments of the present invention, the polymer material includes one or more of silk fibroin, polyvinylidene fluoride, polyimide, nanocellulose, aramid, and aramid sulfone.

[0038] In another aspect of the present invention, a method for preparing a carbon fiber bundle composite filament coated with nanofiber yarn is provided, comprising the following steps:

[0039] (1) The polymer material is mixed with an organic solvent to obtain an electrospinning solution;

[0040] (2) Fix the carbon fiber bundle to the take-up turntable of the electrospinning machine, and then spray the electrospinning liquid onto the surface of the carbon fiber bundle to form nanofiber yarn, thereby obtaining carbon fiber bundle composite filament material covered with nanofiber yarn.

[0041] In this invention, the polymer material is first mixed with an organic solvent to obtain an electrospinning solution.

[0042] In some embodiments of the present invention, the mass percentage concentration of the electrospinning solution is 5-20%, for example, it can be 5%, 8%, 10%, 12%, 15%, 18%, 20%, etc. Specifically, the diameter of the nanofiber yarn can be adjusted by changing the concentration of the electrospinning solution. The organic solvent includes one or more of N,N-dimethylformamide, dichloromethane, formic acid, tetrahydrofuran, and methylpyrrolidone.

[0043] In this invention, carbon fiber bundles are fixed to the take-up turntable of an electrospinning machine, and then the electrospinning solution is sprayed onto the surface of the carbon fiber bundles to form nanofiber yarn, thereby obtaining carbon fiber bundle composite filaments coated with nanofiber yarn.

[0044] In some embodiments of the present invention, the moving speed of the carbon fiber bundle is adjusted by controlling the rotation speed of the take-up turntable, so that the moving speed of the carbon fiber bundle is 2-10 mm / s, for example, 2 mm / s, 5 mm / s, 8 mm / s, 10 mm / s, etc.

[0045] In some embodiments of the present invention, the electrospinning solution is injected into the spinning needle of the electrospinning machine, and the electrospinning solution is sprayed onto the surface of the carbon fiber bundle through the spinning needle to form nanofiber yarn.

[0046] In some embodiments of the present invention, the coating thickness of the nanofiber yarn is 10-30 μm. The thickness of the nanofiber yarn is not specifically limited and can be adjusted according to actual conditions. However, it should be noted that as the coating thickness of the nanofiber yarn increases, the tensile strength of the composite filament will significantly improve. Conversely, if the coating thickness of the nanofiber yarn is too large, the interlaminar shear strength of the composite filament will slightly decrease. This is because excessively thick nanofiber yarn will affect resin penetration, thereby leading to a decrease in interlaminar shear strength.

[0047] In some embodiments of the present invention, the average diameter of the nanofiber yarn is 50-800 nm, for example, it can be 50 nm, 100 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, etc. The average diameter of the nanofiber yarn is mainly related to the voltage, the feed speed of the electrospinning solution, and the type of electrospinning solution. The average diameter of the nanofiber yarn varies under different parameters. For example, when the voltage is 6 kV and the feed speed of the electrospinning solution is 0.5 mL / h, when both the positive and negative electrodes are 8% silk fibroin electrospinning solution, the average diameter of the nanofiber yarn is 160 nm; when the positive electrode is 8% silk fibroin electrospinning solution and the negative electrode is 10% polyvinylidene fluoride electrospinning solution, the average diameter of the nanofiber yarn is 710 nm; and when both the positive and negative electrodes are 10% silk fibroin electrospinning solution, the average diameter of the nanofiber yarn is 175 nm.

[0048] In some embodiments of the present invention, the electrospinning solutions injected into the positive and negative spinning needles of the electrospinning machine can be the same or different, and there is no particular limitation on this; adjustments can be made according to actual conditions. For example, both the positive and negative spinning needles may be injected with silk fibroin electrospinning solution, polyvinylidene fluoride electrospinning solution, polyimide electrospinning solution, nanocellulose electrospinning solution, aramid electrospinning solution, or aramid sulfone electrospinning solution; or the positive spinning needle may be injected with silk fibroin electrospinning solution, while the negative spinning needle may be injected with polyvinylidene fluoride electrospinning solution, polyimide electrospinning solution, nanocellulose electrospinning solution, aramid electrospinning solution, or aramid sulfone electrospinning solution.

[0049] In some embodiments of the present invention, the positive electrode voltage of the electrospinning machine is 4-20kV, for example, it can be 4kV, 6kV, 8kV, 10kV, 12kV, 15kV, 18kV, 20kV, etc., and the negative electrode voltage is -4 to -20kV, for example, it can be -4kV, -6kV, -8kV, -10kV, -12kV, -15kV, -18kV, -20kV, etc.

[0050] In some embodiments of the present invention, the propulsion speed of the electrospinning solution in the spinning needle is 0.2-3 mL / h, for example, it can be 0.2 mL / h, 0.5 mL / h, 1 mL / h, 1.5 mL / h, 2 mL / h, 2.5 mL / h, 3 mL / h, etc.

[0051] In some embodiments of the present invention, the distance between the positive and negative spinning needles of the electrospinning machine is 9-15cm, for example, it can be 9cm, 12cm, or 15cm.

[0052] In some embodiments of the present invention, the distance between the spinning needle of the electrospinning machine and the take-up turntable is 6-10cm, for example, it can be 6cm, 7cm, 8cm, 9cm, 10cm, etc. Specifically, it refers to the distance from the end of the spinning needle near the take-up turntable to the take-up turntable. The rotation speed of the spinning needle and the take-up turntable of the electrospinning machine is 200-1000rpm, for example, it can be 200rpm, 400rpm, 600rpm, 800rpm, 1000rpm, etc.

[0053] like Figure 1The diagram shows a schematic of the electrospinning process of the present invention. The carbon fiber bundle is fixed on the take-up turntable of the electrospinning machine. Both spinning needles face the direction of the take-up turntable, so that the spray direction of the electrospinning liquid forms an acute angle with the carbon fiber bundle. Through the high-speed rotation of the take-up turntable, the electrospinning liquid sprayed from the spinning needles curls and forms on the surface of the carbon fiber bundle, forming a stable nanofiber conical surface at the take-up point of the carbon fiber bundle. Through the high-speed rotation of the take-up turntable, the electrospinning liquid is evenly coated on the surface of the carbon fiber bundle, forming a carbon fiber bundle composite filament material coated with nanofiber yarn.

[0054] The technical solutions of this invention will be clearly and completely described below with reference to specific embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0055] The electrospinning machine used in the following examples is a classic electrospinning machine manufactured by Changsha Nayi Instrument Technology Co., Ltd.

[0056] Example 1

[0057] This embodiment provides a method for preparing carbon fiber bundle composite filaments coated with nanofiber yarn, the specific steps of which are as follows:

[0058] (1) Dissolve silk fibroin in formic acid to obtain a silk fibroin electrospinning solution with a mass percentage concentration of 8%.

[0059] (2) Fix the carbon fiber bundle to the take-up turntable of the electrospinning machine and adjust the rotation speed of the take-up turntable so that the moving speed of the carbon fiber bundle is 2mm / min.

[0060] The carbon fiber bundle is 3K polyacrylonitrile-based carbon fiber BHM3, with a single carbon fiber filament diameter of 7μm, a carbon content of 99%, a tensile strength of 3200MPa, a tensile modulus of 400GPa, and a bulk density of 1.82g / cm³. 3 .

[0061] (3) 8% silk fibroin electrospinning solution is injected into both the positive and negative spinning needles of the electrospinning machine. The electrospinning solution is sprayed from the spinning needles onto the surface of the carbon fiber bundle to form nanofiber yarn, thus obtaining carbon fiber bundle composite filament material coated with nanofiber yarn (hereinafter referred to as "composite filament material").

[0062] The electrospinning machine has a positive electrode voltage of 6kV, a negative electrode voltage of -6kV, a propulsion speed of 0.5mL / h for the electrospinning solution, a distance of 12cm between the positive and negative electrode spinning needles, a distance of 8cm between the spinning needles and the take-up turntable, a rotation speed of 800rpm for the take-up turntable, an average diameter of 160nm for the nanofiber yarn, and a coating thickness of 30μm for the nanofiber yarn.

[0063] like Figures 2 to 3 The images shown are scanning electron microscope (SEM) images of the surface and cross-section of the carbon fiber bundle composite filament coated with nanofiber yarn prepared in this embodiment.

[0064] from Figure 2 It can be seen that the surface of the carbon fiber bundle composite filament has reached the nanoscale, exhibiting extremely high precision and uniformity. During the winding process of the nanofiber yarn, the nanofiber yarn exhibits a certain orientation, which can not only enhance the mechanical properties of the composite filament, but also effectively improve its weaving performance.

[0065] from Figure 3 As can be seen, the nanofiber yarn is tightly bonded to the outer layer of the carbon fiber bundle. This tight bonding method significantly enhances the bundle properties of the carbon fiber, making the overall structure more stable and robust. At the same time, the state of the nanofiber yarn is also clearly presented. Its uniform distribution and tight arrangement can effectively improve the mechanical properties and weaving properties of the composite bundle.

[0066] Examples 2-9

[0067] Examples 2-9 are basically the same as Example 1, except for the types of electrospinning solutions used in the positive and negative electrode spinning needles and some electrospinning parameters, as detailed in Table 1. The polyvinylidene fluoride electrospinning solution is obtained by dissolving polyvinylidene fluoride in N,N-dimethylformamide.

[0068] Table 1

[0069]

[0070] Comparative Example 1

[0071] This comparative example is a carbon fiber bundle without nanofiber yarn coating, namely 3K polyacrylonitrile-based carbon fiber BHM3, with a carbon content of ≥99%, a tensile strength of 3200 MPa, a tensile modulus of 400 GPa, and a bulk density of 1.82 g / cm³. 3 .

[0072] The interlaminar shear strength, bending strength, impact strength, hook strength, tensile strength, and tensile strength of the composite filaments prepared in Examples 1-9 and the carbon fiber bundle of Comparative Example 1 were measured. The results are shown in Table 2.

[0073] (1) Test method for hook strength and first tensile strength: The composite filaments of Examples 1-9 and the carbon fiber bundle of Comparative Example 1 were used as the first test samples.

[0074] The first sample to be tested was tested using a universal tensile testing machine. The test standard for hook strength was GJB 1982-94, and the test standard for the first tensile strength was GB / T 3362(2005). The test for the first tensile strength was performed on a sample with a length of 200mm.

[0075] (2) Test methods for interlaminar shear strength and second tensile strength: The same amount of bisphenol A type epoxy resin 6101 was coated on the surface of the composite filaments of Examples 1-9 and the carbon fiber bundle of Comparative Example 1. The samples were cured at 80°C for 2 hours with triethylenetetramine as a curing agent to obtain the second test sample. The volume ratio of composite filament / carbon fiber to bisphenol A type epoxy resin 6101 was 6:4, and the mass ratio of bisphenol A type epoxy resin 6101 to curing agent was 10:1.

[0076] The second sample was tested using a universal tensile testing machine. The interlaminar shear strength test standard was JC / T773-82, and the second tensile strength test standard was GB / T 3362(2005). The second tensile strength test was performed on a sample with a length of 150 mm.

[0077] Table 2

[0078]

[0079]

[0080] As shown in Table 2, compared to carbon fiber bundles without nanofiber yarn coating, the hook strength of the carbon fiber bundle composite filament coated with nanofiber yarn of the present invention can increase by up to 228.77%. This is because the nanofiber yarn acts as a buffer when the composite filament is subjected to lateral force, which can significantly improve the bending resistance of the carbon fiber bundle, thereby improving its bending resistance and abrasion resistance during fabric processing. The relatively small change in tensile strength is because the winding tension during electrospinning may cause damage to the carbon fiber filaments in the carbon fiber bundle.

[0081] like Figure 4The images show scanning electron microscope (SEM) images of the cross-section (left) and longitudinal section (right) of the second test sample. As can be seen from the images, the second test sample exhibits a clear layered structure. Specifically, from the outside in, the second test sample consists of a resin layer, nanofiber yarn, and carbon fiber bundles. The nanofiber yarn plays a crucial transitional role between the resin layer and the carbon fiber bundles. This transition not only effectively alleviates the interfacial stress between the different materials but also further enhances the overall performance and durability of the composite material (the second test sample), enabling the composite material to maintain its lightweight nature while possessing excellent mechanical and weaving properties.

[0082] In addition, the present invention also tested the processing flexibility of the composite filament of Example 8 and the carbon fiber bundle of Comparative Example 1, and conducted knotting tests on both, such as... Figure 5 As shown, the carbon fiber bundle in Comparative Example 1 broke after knotting, while the composite filament in Example 8 remained intact. This demonstrates that the carbon fiber bundle composite filament coated with nanofiber yarn of the present invention has excellent weaving properties and good processing flexibility.

[0083] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A carbon fiber bundle composite filament coated with nanofiber yarn, characterized in that, It includes carbon fiber bundles and nanofiber yarns, with the nanofiber yarns covering the outer surface of the carbon fiber bundles; the carbon fiber bundles are high-modulus carbon fiber bundles, and the nanofiber yarns are prepared from polymer materials by conjugated electrospinning. The polymer material includes one or more of the following: silk fibroin, polyvinylidene fluoride, polyimide, nanocellulose, aramid, and aramid sulfone. The carbon fiber bundle consists of 1000-36000 high-modulus carbon fiber filaments, each with a diameter of 5-7 μm. The high-modulus carbon fiber filaments have a carbon content ≥99%, a tensile strength ≥3200 MPa, a tensile modulus ≥350 GPa, and a bulk density of 1.81-1.83 g / cm³. 3 .

2. The carbon fiber bundle composite filament coated with nanofiber yarn according to claim 1, characterized in that, The coating thickness of the nanofiber yarn is 10-30 μm, and the average diameter of the nanofiber yarn is 50-800 nm.

3. A method for preparing a carbon fiber bundle composite filament coated with nanofiber yarn according to any one of claims 1-2, characterized in that, The process includes the following steps: (1) mixing polymer materials with organic solvents to obtain electrospinning solution; (2) fixing carbon fiber bundles to the take-up turntable of an electrospinning machine, and then spraying the electrospinning solution onto the surface of the carbon fiber bundles to form nanofiber yarn, thereby obtaining carbon fiber bundle composite filaments covered with nanofiber yarn.

4. The method for preparing the carbon fiber bundle composite filament coated with nanofiber yarn according to claim 3, characterized in that, The electrospinning solution has a mass percentage concentration of 5-20%; the organic solvent includes one or more of N,N-dimethylformamide, dichloromethane, formic acid, tetrahydrofuran, and methylpyrrolidone.

5. The method for preparing carbon fiber bundle composite filaments coated with nanofiber yarn according to claim 3, characterized in that, The carbon fiber bundle moves at a speed of 2-10 mm / s.

6. The method for preparing the carbon fiber bundle composite filament coated with nanofiber yarn according to claim 3, characterized in that, The distance between the spinning needle and the take-up turntable of the electrospinning machine is 6-10 cm, and the rotation speed of the take-up turntable is 200-1000 rpm; the propulsion speed of the electrospinning solution is 0.2-3 mL / h.

7. The method for preparing the carbon fiber bundle composite filament coated with nanofiber yarn according to claim 3, characterized in that, The distance between the positive and negative spinning needles of the electrospinning machine is 9-15 cm; the electrospinning solutions sprayed from the positive and negative spinning needles of the electrospinning machine may be the same or different.

8. The method for preparing carbon fiber bundle composite filaments coated with nanofiber yarn according to any one of claims 3-7, characterized in that, The positive electrode voltage of the electrospinning machine is 4-20kV, and the negative electrode voltage is -4 to -20kV.

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