A green, low-cost sugar-based multifunctional carbon fiber and its preparation method

Abstract

The present invention discloses a green, low-cost sugar-based multifunctional carbon fiber and a preparation method thereof, belonging to the technical field of carbon fiber preparation. The present invention uses water-soluble sugars, gel monomers, reinforcing phases and spinning aids as main raw materials, and prepares carbon fiber precursors containing multifunctional phases in situ through wet spinning and drying, and then realizes efficient synthesis of multifunctional carbon fibers through pre-carbonization and carbonization treatment. The multifunctional phase introduced into the carbon fiber prepared by the present invention gives the carbon fiber excellent properties such as high temperature resistance, oxidation resistance, corrosion resistance, high strength, high electrical conductivity, high thermal conductivity and high specific surface area, making it expected to be used in a variety of fields such as aerospace, automotive industry, electronic equipment, energy field, construction engineering, medical equipment and environmental protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon fiber preparation, and in particular relates to a green, low-cost sugar-based multifunctional carbon fiber and a preparation method thereof. Background Art

[0002] Traditional carbon fiber has excellent properties such as high strength, high modulus, light weight, high temperature resistance, and corrosion resistance. It is widely used in aerospace, automobile manufacturing, wind turbine blades, sports equipment, and building reinforcement. It can significantly improve the structural performance and durability of the material.

[0003] However, traditional carbon fibers have significant limitations in terms of multifunctionalization. It is difficult to directly introduce a multifunctional phase during the precursor preparation stage. This can usually only be achieved through secondary functionalization of the finished carbon fibers. This late modification process not only relies on toxic and hazardous substances, increasing the environmental burden, but also makes the process more complicated. In addition, the preparation process of traditional polyacrylonitrile (PAN)-based carbon fibers is complex and energy-intensive, requiring multiple steps of high-temperature carbonization, which limits production and costs. The emission of harmful gases during the preparation process and the difficulty of recycling also have an adverse impact on the environment. Moreover, the main raw materials of carbon fibers rely on non-renewable fossil resources, such as PAN and asphalt, which consume a lot of resources. The above problems limit the application potential of carbon fibers in multifunctional composite materials such as electrical conductivity, thermal conductivity, and energy storage. New methods are urgently needed to promote their multifunctionalization and sustainable development. Summary of the Invention

[0004] The purpose of the present invention is to provide a green, low-cost sugar-based multifunctional carbon fiber and a preparation method thereof. By using water-soluble sugars, gel monomers, reinforcing phases and spinning aids as the main raw materials, carbon fiber precursors containing multifunctional phases are prepared in situ by wet spinning and drying, and then pre-carbonized and carbonized to achieve efficient synthesis of multifunctional carbon fibers. Compared with traditional carbon fibers that require functional modification in the later stage, the present invention can directly introduce reinforcing phases in the precursor preparation stage, so that the multifunctional phases are evenly distributed, significantly simplifying the process, reducing energy consumption, not relying on non-renewable fossil resources, and having the advantages of being green, environmentally friendly, and easy to operate.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a green and low-cost method for preparing sugar-based multifunctional carbon fibers, comprising the following steps:

[0007] Dissolving a gel monomer, a water-soluble sugar, and a cross-linking agent in water to obtain a solution A; adding a reinforcing phase, a spinning aid, an initiator, and a catalyst to the solution A to prepare a spinning solution;

[0008] Prepare a solution identical to solution A, add an ionic gelling agent, and use it as a coagulation bath;

[0009] A solution containing the gel monomer, cross-linking agent, reinforcing phase and spinning aid omitted from the spinning solution is used as the water bath solution;

[0010] Obtaining multifunctional carbon fiber precursor by wet spinning using the spinning solution, the coagulation bath and the water bath solution;

[0011] The multifunctional carbon fiber precursor is pre-carbonized to obtain pre-carbonized multifunctional fibers; and the pre-carbonized multifunctional fibers are carbonized to obtain the green, low-cost sugar-based multifunctional carbon fibers;

[0012] The reinforcing phase includes diamond, graphene, graphene oxide, carbon nanotubes, fullerene, silicon, boron, ZrO2, HfO2, Ta2O5, Al2O3 or TiO2.

[0013] The present invention uses water-soluble sugars, gel monomers, a reinforcing phase, and a spinning aid as the main raw materials. Through wet spinning and drying, carbon fiber precursors containing a multifunctional phase are prepared in situ. The coagulation bath and water bath solutions prepared in the wet spinning process can be recycled multiple times. The present invention introduces a multifunctional reinforcing phase during the precursor preparation stage; then, through pre-carbonization, volatiles and moisture are removed, promoting the caramelization reaction, reducing internal stress, avoiding cracking and breakage, completing the stabilization treatment, and ensuring fiber uniformity and strength. Finally, carbonization is performed to obtain the multifunctional carbon fiber.

[0014] Optionally, the gel monomer includes one or more of acrylamide, acrylic acid, methacrylic acid, polyethylene glycol diacrylate and N-isopropylacrylamide.

[0015] Optionally, the water-soluble sugar includes one or more of glucose, fructose, galactose, maltose, sucrose, lactose and oligofructose.

[0016] Optionally, the crosslinking agent includes one or more of N,N'-methylenebisacrylamide, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diacrylamide ethylenediamine, polyethylene glycol diacrylate, trimethylolpropane triacrylate, divinyl urea, N,N'-ethylenebisacrylamide and N,N'-bis(acryloyloxyethyl)urea.

[0017] Preferably, the mass ratio of the gel monomer, the water-soluble sugar, the cross-linking agent and water in the solution A is 1-20:10-60:0.05-2:100.

[0018] Optionally, the spinning aid includes one or more of sodium alginate, sodium polyacrylate and sodium carboxymethyl cellulose.

[0019] Optionally, the initiator includes one or more of ammonium persulfate, azobisisobutyronitrile, potassium persulfate and hydrogen peroxide.

[0020] Optionally, the catalyst includes one or more of triethanolamine, sodium bisulfite and tetramethylethylenediamine.

[0021] Preferably, in the spinning solution, the reinforcing phase is added in the form of micro-nano powder or aqueous dispersion, and the spinning aid, initiator and catalyst are added in the form of aqueous solution, wherein the particle size of the reinforcing phase does not exceed 30 μm, the concentration of the reinforcing phase aqueous dispersion is 0.05-30wt.%, the concentration of the spinning aid aqueous solution is 1-10wt.%, the concentration of the initiator aqueous solution is 0.5-20wt.%, and the concentration of the catalyst aqueous solution is 0.5-20wt.%.

[0022] Preferably, in the spinning solution, the mass ratio of the reinforcing phase to the water in the solution A is 0.05 to 20:100, and the mass ratio of the spinning aid to the water in the solution A is 0.5 to 10:100.

[0023] In the spinning solution, the amount of initiator and catalyst added is determined by the amount of gel monomer used, and can be added according to conventional amounts in the art.

[0024] Optionally, the ionic gelling agent includes calcium chloride and / or calcium acetate.

[0025] Preferably, the ionic gelling agent accounts for 1 to 20% of the mass of the coagulation bath.

[0026] Preferably, during the wet spinning process, the temperature of the water bath solution is 25-90°C.

[0027] Preferably, in the wet spinning process, the process parameters are: spinning needle inner hole diameter 30-200 μm, spinning speed 50-2000 μL / min, drawing machine speed 1-20 m / min, drying temperature 50-300° C., and drying time 1-30 min.

[0028] Preferably, the pre-carbonization is performed by gradient temperature increase, with the maximum temperature not exceeding 350°C.

[0029] More specific operating steps are: gradually heating the multifunctional carbon fiber precursor in a continuous pre-carbonization furnace, and uniformly pulling it through each temperature zone to achieve stable pre-carbonization and obtain pre-carbonized fibers with uniform quality; the wire speed is preferably 0.02 to 1 m / min to ensure that the fiber gradually adapts to the heating process to avoid damage to the internal structure, and the precursor has sufficient residence time in each temperature zone to react and form an ideal micro-nano structure.

[0030] Preferably, the carbonization is carried out under anaerobic conditions, with the temperature being raised directly or gradually to 800-2000° C., with a heating rate of 1-20° C. / min, and the holding time of each gradient being 0.5-6 h.

[0031] The second technical solution of the present invention: provides a green, low-cost, sugar-based multifunctional carbon fiber prepared according to the above-mentioned green, low-cost, sugar-based multifunctional carbon fiber preparation method.

[0032] The third technical solution of the present invention is to provide a multifunctional graphite fiber obtained by graphitizing the pre-carbonized multifunctional fiber or the green, low-cost sugar-based multifunctional carbon fiber prepared according to the above preparation method.

[0033] Preferably, the graphitization temperature is 2000-3000° C., the heating rate is 0.5-20° C. / min, and the holding time is 0.5-6 h.

[0034] The beneficial technical effects of the present invention are as follows:

[0035] The present invention addresses the problems of long cycle, complex process, high energy consumption, high pollution and strong dependence on non-renewable fossil resources in the traditional carbon fiber preparation process, and innovatively proposes a method for preparing carbon fiber by directly introducing a multifunctional phase in the precursor preparation stage. The method uses water-soluble sugars, gel monomers, reinforcing phases and spinning aids as raw materials, adopts wet spinning to prepare precursor containing multifunctional phases, and through pre-carbonization and carbonization steps, realizes the efficient synthesis of multifunctional carbon fibers. These multifunctional phases give carbon fibers excellent properties such as high temperature resistance, oxidation resistance, corrosion resistance, high strength, high electrical conductivity, high thermal conductivity and high specific surface area, making them expected to be applied in aerospace, automotive industry, electronic equipment, energy field, construction engineering, medical equipment and environmental protection and other fields. The method provided by the present invention not only has a simple process flow, low energy consumption and low environmental burden, but also ensures the uniform distribution of the multifunctional phase, showing the advantages of green environmental protection and easy operation, and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a continuous collection production line for wet spinning.

[0037] Figure 2 This is a picture of the continuous pre-carbonization furnace used in the embodiments of the present invention.

[0038] Figure 3 It is the equipment for carbonization or graphitization in the embodiment of the present invention.

[0039] Figure 4 This is the temperature zone setting diagram of the continuous pre-carbonization furnace in Examples 1 and 3.

[0040] Figure 5This is the temperature zone setting diagram of the continuous pre-carbonization furnace in Example 2.

[0041] Figure 6 This is a picture of the diamond-reinforced carbon fiber prepared in Example 1.

[0042] Figure 7 This is a TEM image of the diamond-reinforced carbon fiber prepared in Example 1.

[0043] Figure 8 This is a graph showing the tensile strength of the diamond-reinforced carbon fiber prepared in Example 1.

[0044] Figure 9 These are the oxidation resistance test results of the high-temperature resistant and oxidation-resistant graphite fiber prepared in Example 3. DETAILED DESCRIPTION

[0045] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0046] In addition, for numerical ranges in the present invention, it is understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intervening value in the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] The wet spinning continuous collection production line in the embodiment of the present invention is shown in FIG. Figure 1 .

[0050] The picture of the continuous pre-carbonization furnace used in the embodiment of the present invention is shown in FIG. Figure 2 .

[0051] The equipment for carbonization or graphitization in the embodiment of the present invention is shown in FIG. Figure 3 .

[0052] Example 1

[0053] (1) Preparation of spinning solution: First, 12 g of acrylic acid, 40 g of glucose, and 0.5 g of ethylene glycol diacrylate were mixed and dissolved in 110 mL of deionized water, and stirred to form a uniform transparent solution. Then, 48 g of a 5% diamond aqueous dispersion (diamond particle size of 10 nm) was added, along with 50 mL of a 4% sodium alginate aqueous solution, 4 mL of a 10% ammonium persulfate aqueous solution, and 4 mL of a 10% tetramethylethylenediamine aqueous solution. Ultrasonication and stirring were performed to form a uniform solution. The bubbles in the spinning solution were removed by a debubbler to obtain a spinning solution for use.

[0054] (2) Prepare the coagulation bath: Dissolve 1800 g of acrylic acid, 6000 g of glucose, 150 g of ethylene glycol diacrylate, and 1800 g of calcium chloride in 16500 mL of deionized water. Stir in a coagulation bath to form a uniform, transparent solution. During the spinning process, turn on the circulation pump of the coagulation bath to circulate the coagulation bath in a fixed manner. The prepared coagulation bath can be reused multiple times.

[0055] (3) Preparation of water bath solution: 6000 g of glucose, 600 mL of a 10% by mass aqueous solution of ammonium persulfate, and 600 mL of a 10% by mass aqueous solution of tetramethylethylenediamine were mixed and dissolved in 16500 mL of deionized water. The mixture was stirred in a constant temperature water bath to form a uniform transparent solution. During the spinning operation, the heating device of the constant temperature water bath was turned on to stabilize the water bath temperature at 70°C. In addition, the prepared water bath solution can be recycled multiple times.

[0056] (4) Preparation of carbon fiber precursor: Use a syringe to draw the prepared spinning solution and connect the spinning needle with an inner diameter of 80 μm. Then use a high-precision syringe pump to inject the spinning solution into the coagulation bath through the spinning needle at a speed of 500 μL / min to generate gel fiber. The gel fiber is pulled by a drawing machine and passed through a 70℃ constant temperature water washing tank. The drawing machine speed is 8m / min, and then it enters a 120℃ blast dryer for drying. Finally, it is collected into bundles by a collection roller to obtain carbon fiber precursor.

[0057] (5) Pre-carbonization: The carbon fiber precursor is passed through the continuous pre-carbonization furnace at a speed of 0.05m / min through the unwinding machine and the traction machine. The precursor is pulled through each temperature zone in a uniform manner to achieve stable pre-carbonization and obtain pre-carbonized fibers with uniform quality. The pre-carbonization production line adopts a 5-section furnace design, each furnace section has 5 temperature zones, a total of 25 temperature zones, gradually rising from 25°C to 220°C. The temperature zone distribution ranges from low temperature, medium temperature to high temperature, gradually removing volatiles and moisture, promoting caramel reaction, and completing the final stabilization treatment to ensure fiber uniformity and strength. See the temperature zone setting of the continuous pre-carbonization furnace for details. Figure 4 .

[0058] (6) Carbonization: The pre-carbonized fiber was carbonized in a carbonization furnace. Under vacuum conditions, the temperature was raised to 360°C, 920°C, 1050°C, and 1400°C at a heating rate of 4°C / min, and each temperature was kept for 2 h. The furnace was then cooled to room temperature to obtain diamond-reinforced carbon fiber.

[0059] (7) Graphitization: The multifunctional carbon fiber was graphitized using a graphitization furnace. Under vacuum conditions, the temperature was raised to 1800°C at a heating rate of 4°C / min, and then to 2800°C at a heating rate of 2°C / min. The temperature was kept at this temperature for 2 h, and the furnace was cooled to room temperature to obtain diamond-reinforced graphite fiber.

[0060] The picture of diamond reinforced carbon fiber prepared in Example 1 is shown in Figure 6 .

[0061] The TEM image of the diamond-reinforced carbon fiber prepared in Example 1 is shown in FIG. Figure 7 .

[0062] from Figure 7 As can be seen in the figure, this is a transmission electron microscope (TEM) image of diamond-reinforced carbon fiber, which clearly shows the microstructural characteristics of the sample. Two significant areas can be observed in the image: the ordered lattice fringes represent the diamond phase, while the matrix is ​​mainly composed of nanocrystalline graphite and amorphous carbon. The lattice fringes of the diamond phase are clear and regular, indicating that it is highly crystallized and has extremely high structural stability; while the matrix part shows a relatively disordered feature, reflecting the random distribution of amorphous carbon and nanocrystalline graphite. In addition, the illustration is a selected area electron diffraction (SAED) pattern, which shows a combined structure of discrete spots and continuous rings, where the spots correspond to the highly ordered crystal features of the diamond phase, while the continuous rings reflect the presence of amorphous carbon and nanocrystalline graphite.

[0063] The tensile strength of the diamond-reinforced carbon fiber prepared in Example 1 is shown in FIG. Figure 8 , where 1#, 2#, and 3# are the tensile strengths of different segments of the diamond-reinforced carbon fiber prepared in Example 1.

[0064] Example 2

[0065] (1) Preparation of spinning solution: First, 36 g of methacrylic acid, 120 g of sucrose and 3 g of N,N'-methylenebisacrylamide were mixed and dissolved in 330 mL of deionized water, and stirred to form a uniform transparent solution. Then, 72 g of a 5% boron aqueous dispersion with a boron particle size of 10 nm was added, along with 120 mL of a 5% sodium alginate aqueous solution, 12 mL of a 10% azobisisobutyronitrile aqueous solution, and 12 mL of a 10% sodium bisulfite aqueous solution. Ultrasonication and stirring were performed to form a uniform solution. The bubbles in the spinning solution were removed by a debubbler to obtain a spinning solution for use.

[0066] (2) Prepare a coagulation bath: Dissolve 1800 g of methacrylic acid, 6000 g of sucrose, 150 g of N,N'-methylenebisacrylamide, and 1800 g of calcium chloride in 16500 mL of deionized water. Stir the mixture in a coagulation bath to form a uniform, transparent solution. During the spinning process, turn on the circulation pump of the coagulation bath to circulate the coagulation bath in a directional manner. The prepared coagulation bath can be reused multiple times.

[0067] (3) Preparation of a water bath solution: 6000 g of sucrose, 600 mL of a 10% by mass aqueous solution of azobisisobutyronitrile, and 600 mL of a 10% by mass aqueous solution of sodium bisulfite were mixed and dissolved in 16500 mL of deionized water. The mixture was stirred in a constant temperature water bath to form a uniform transparent solution. During the spinning operation, the heating device of the constant temperature water bath was turned on to stabilize the water bath temperature at 60°C. In addition, the prepared water bath solution can be recycled multiple times.

[0068] (4) Preparation of carbon fiber precursor: Use a syringe to draw the prepared spinning solution and connect the spinning needle with an inner hole diameter of 60μm. Then use a high-precision syringe pump to inject the spinning solution into the coagulation bath through the spinning needle at a speed of 400μL / min to generate gel fiber. The gel fiber is pulled by a drawing machine and passed through a 60℃ constant temperature water washing tank. The drawing machine speed is 8m / min, and then it enters a 90℃ blast dryer for drying. Finally, it is collected into bundles by a collection roller to obtain carbon fiber precursor.

[0069] (5) Pre-carbonization: The carbon fiber precursor is passed through the continuous pre-carbonization furnace at a speed of 0.1m / min through the unwinding machine and the traction machine. The precursor is pulled through each temperature zone in a uniform manner to achieve stable pre-carbonization and obtain pre-carbonized fibers with uniform quality. The pre-carbonization production line adopts a 5-section furnace design, each furnace section has 5 temperature zones, a total of 25 temperature zones, gradually rising from 25°C to 220°C. The temperature zone distribution ranges from low temperature, medium temperature to high temperature, gradually removing volatiles and moisture, promoting caramel reaction, and completing the final stabilization treatment to ensure fiber uniformity and strength. See the temperature zone setting of the continuous pre-carbonization furnace for details. Figure 5 .

[0070] (6) Carbonization: The pre-carbonized fiber was carbonized in a carbonization furnace. Under argon conditions, the temperature was raised to 1400°C at a heating rate of 2°C / min, kept at this temperature for 2 h, and then cooled to room temperature to obtain highly conductive carbon fiber.

[0071] (7) Graphitization: The highly conductive carbon fibers were graphitized using a graphitization furnace. Under argon conditions, the temperature was raised to 1800°C at a heating rate of 8°C / min, and then to 2600°C at a heating rate of 4°C / min. The temperature was kept at this temperature for 3 h, and the furnace was cooled to room temperature to obtain highly conductive graphite fibers.

[0072] The conductivity of the highly conductive carbon fiber prepared in Example 2 is 1.1×10 5 S / m.

[0073] Example 3

[0074] (1) Preparation of spinning solution: First, 12 g of acrylic acid, 40 g of glucose, and 0.5 g of ethylene glycol diacrylate were mixed and dissolved in 110 mL of deionized water and stirred to form a uniform transparent solution. Then, 48 g of a 5% by mass zirconium oxide aqueous dispersion, 50 mL of a 4% by mass sodium alginate aqueous solution, 4 mL of a 10% by mass ammonium persulfate aqueous solution, and 4 mL of a 10% by mass tetramethylethylenediamine aqueous solution were added. The solution was ultrasonically stirred to form a uniform solution. The bubbles in the spinning solution were removed by a degassing machine to obtain a spinning solution for use.

[0075] (2) Prepare the coagulation bath: Dissolve 1800 g of acrylic acid, 6000 g of glucose, 150 g of ethylene glycol diacrylate, and 1800 g of calcium chloride in 16500 mL of deionized water. Stir in a coagulation bath to form a uniform, transparent solution. During the spinning process, turn on the circulation pump of the coagulation bath to circulate the coagulation bath in a fixed manner. The prepared coagulation bath can be reused multiple times.

[0076] (3) Preparation of water bath solution: 6000 g of glucose, 600 mL of a 10% by mass aqueous solution of ammonium persulfate, and 600 mL of a 10% by mass aqueous solution of tetramethylethylenediamine were mixed and dissolved in 16500 mL of deionized water. The mixture was stirred in a constant temperature water bath to form a uniform transparent solution. During the spinning operation, the heating device of the constant temperature water bath was turned on to stabilize the water bath temperature at 70°C. In addition, the prepared water bath solution can be recycled multiple times.

[0077] (4) Preparation of carbon fiber precursor: Use a syringe to draw the prepared spinning solution and connect the spinning needle with an inner diameter of 80 μm. Then use a high-precision syringe pump to inject the spinning solution into the coagulation bath through the spinning needle at a speed of 500 μL / min to generate gel fiber. The gel fiber is pulled by a drawing machine and passed through a 70℃ constant temperature water washing tank. The drawing machine speed is 8m / min, and then it enters a 120℃ blast dryer for drying. Finally, it is collected into bundles by a collection roller to obtain carbon fiber precursor.

[0078] (5) Pre-carbonization: The carbon fiber precursor is passed through the continuous pre-carbonization furnace at a speed of 0.05m / min through the unwinding machine and the traction machine. The precursor is pulled through each temperature zone in a uniform manner to achieve stable pre-carbonization and obtain pre-carbonized fibers with uniform quality. The pre-carbonization production line adopts a 5-section furnace design, each furnace section has 5 temperature zones, a total of 25 temperature zones, gradually rising from 25°C to 220°C. The temperature zone distribution ranges from low temperature, medium temperature to high temperature, gradually removing volatiles and moisture, promoting caramel reaction, and completing the final stabilization treatment to ensure fiber uniformity and strength. See the temperature zone setting of the continuous pre-carbonization furnace for details. Figure 4 .

[0079] (6) Graphitization: The pre-carbonized fiber was graphitized in a graphitization furnace. Under vacuum conditions, the temperature was raised to 1800°C at a heating rate of 4°C / min, and then to 2800°C at a heating rate of 2°C / min. The temperature was kept at this temperature for 3 h, and the furnace was cooled to room temperature to obtain high-temperature resistant and oxidation-resistant graphite fiber.

[0080] The oxidation resistance test results of the high temperature resistant and oxidation resistant graphite fiber prepared in Example 3 are shown in Figure 9 .

[0081] from Figure 9 As can be seen in the figure, the test results of the oxidation resistance of zirconia reinforced graphite fiber are shown, including the relationship curves of the sample's mass loss (Weight%), differential thermogravimetric (DTG% / min) and heat flow (Heat flow W / g) with temperature. The mass loss curve (black) shows that the starting temperature of the sample's oxidation is 764°C, at which time the sample begins to experience significant mass loss. The DTG curve (red) shows the maximum rate point of the oxidation reaction, indicating that the oxidation reaction is most intense within this temperature range. The heat flow curve (blue) shows an obvious exothermic process (Exothermic), further indicating that the oxidation reaction of the sample is an exothermic reaction. From Figure 9 As can be seen in the graphite fiber's oxidation onset temperature of 764°C, the graphite fiber's oxidation resistance is significantly improved, likely due to the zirconia reinforcement. Zirconia forms a protective oxide coating on the fiber surface, inhibiting the penetration of oxidants and thus slowing the oxidative decomposition of the graphite fiber. Overall, these results demonstrate that zirconia-reinforced graphite fiber exhibits excellent oxidation resistance in high-temperature environments, making it ideal for specialized engineering applications requiring both high-temperature resistance and oxidation resistance.

[0082] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A green and low-cost method for preparing sugar-based multifunctional carbon fibers, characterized in that: The following steps are involved: Dissolving gel monomer, water-soluble sugar and cross-linking agent in water to obtain solution A; Adding a reinforcing phase, a spinning aid, an initiator and a catalyst to the solution A to prepare a spinning solution; Prepare a solution identical to solution A, add an ionic gelling agent, and use it as a coagulation bath; A solution containing the gel monomer, cross-linking agent, reinforcing phase and spinning aid omitted from the spinning solution is used as the water bath solution; Obtaining multifunctional carbon fiber precursor by wet spinning using the spinning solution, the coagulation bath and the water bath solution; The multifunctional carbon fiber precursor is pre-carbonized to obtain pre-carbonized multifunctional fibers; and the pre-carbonized multifunctional fibers are carbonized to obtain the green, low-cost sugar-based multifunctional carbon fibers; The reinforcing phase includes diamond, graphene, graphene oxide, carbon nanotubes, fullerene, silicon, boron, ZrO2, HfO2, Ta2O5, Al2O3 or TiO2; The gel monomer includes one or more of acrylamide, acrylic acid, methacrylic acid, polyethylene glycol diacrylate and N-isopropylacrylamide; The water-soluble sugar includes one or more of glucose, fructose, galactose, maltose, sucrose, lactose and oligofructose; The crosslinking agent includes one or more of N,N'-methylenebisacrylamide, ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, divinyl urea, N,N'-ethylenebisacrylamide and N,N'-bis(acryloyloxyethyl)urea; The spinning aid comprises one or more of sodium alginate, sodium polyacrylate and sodium carboxymethyl cellulose; The wet spinning process includes: injecting the spinning solution into the coagulation bath through a spinning needle to generate gel fibers; and the gel fibers pass through the water bath solution under traction to obtain carbon fiber precursors.

2. The method for preparing green, low-cost sugar-based multifunctional carbon fibers according to claim 1, characterized in that: The mass ratio of the gel monomer, the water-soluble sugar, the cross-linking agent and water in the solution A is 1-20:10-60:0.05-2:

100.

3. The method for preparing green, low-cost sugar-based multifunctional carbon fibers according to claim 1, characterized in that: In the spinning solution, the reinforcing phase is added in the form of micro-nano powder or aqueous dispersion, and the spinning aid, initiator and catalyst are added in the form of aqueous solution, wherein the particle size of the reinforcing phase does not exceed 30 μm, the concentration of the reinforcing phase aqueous dispersion is 0.05~30wt.%, the concentration of the spinning aid aqueous solution is 1~10wt.%, the concentration of the initiator aqueous solution is 0.5~20wt.%, and the concentration of the catalyst aqueous solution is 0.5~20wt.%.

4. The method for preparing green, low-cost sugar-based multifunctional carbon fibers according to claim 1, characterized in that: In the spinning solution, the mass ratio of the reinforcing phase to the water in the solution A is 0.05-20:100, and the mass ratio of the spinning aid to the water in the solution A is 0.5-10:

100.

5. The method for preparing green, low-cost sugar-based multifunctional carbon fibers according to claim 1, characterized in that: The ionic gelling agent accounts for 1 to 20% of the mass of the coagulation bath.

6. The method for preparing green, low-cost sugar-based multifunctional carbon fibers according to claim 1, characterized in that: During the wet spinning process, the process parameters are: spinning needle inner hole diameter 30-200 μm, spinning speed 50-2000 μL / min, drawing machine speed 1-20 m / min, drying temperature 50-300° C., and drying time 1-30 min.

7. The method for preparing green, low-cost sugar-based multifunctional carbon fibers according to claim 1, characterized in that: The pre-carbonization is performed by gradient temperature increase, with the maximum temperature not exceeding 350°C.

8. The method for preparing green, low-cost sugar-based multifunctional carbon fibers according to claim 1, characterized in that: The carbonization is carried out under oxygen-free conditions, with the temperature being raised directly or gradually to 800-2000° C., with a heating rate of 1-20° C. / min, and the holding time of each gradient being 0.5-6 h.

9. A green, low-cost, sugar-based multifunctional carbon fiber prepared according to the method for preparing a green, low-cost, sugar-based multifunctional carbon fiber according to any one of claims 1 to 8.

10. A multifunctional graphite fiber, characterized in that: The green, low-cost sugar-based multifunctional carbon fiber is obtained by graphitizing the preparation method according to any one of claims 1 to 8.

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