A cellulose-based high thermal conductivity phase change fiber and its preparation method

Abstract

The present invention discloses a cellulose-based high-thermal-conductivity phase-change fiber and a preparation method thereof. The method comprises the following steps: activating cellulose, dissolving hydroxylated boron nitride nanosheets and activated cellulose to obtain a shell spinning solution; emulsifying the hydroxylated boron nitride nanosheets, nanocellulose, and a phase-change medium in deionized water to obtain a core spinning solution; and preparing the cellulose-based high-thermal-conductivity phase-change fiber by a one-step coaxial wet spinning process. The cellulose, the phase-change medium, and the high-thermal-conductivity component BNNs-OH are assembled into a phase-change fiber material, which can exhibit phase change capability at 20°C-60°C, has a thermal conductivity of 0.5-10 W / (m·K), and has good thermal management performance and excellent thermal conductivity. As a thermal management fabric, the fiber is composed of biomass components, can be prepared in a one-step process under mild conditions, has strong operability, and high production efficiency, and is suitable for large-scale production and application.

Description

Technical Field

[0001] The present invention belongs to the field of thermal regulation technology, and specifically relates to a cellulose-based high thermal conductivity phase change fiber and a preparation method thereof. Background Art

[0002] With the development of science and technology, people have developed various advanced thermal regulation devices and technologies to provide two-way thermal regulation (i.e., heating and cooling) for the human body to meet the thermal comfort needs under different environmental conditions. This has resulted in a large amount of carbon dioxide emissions and consumed a lot of energy. In this context, the emergence of smart phase change fibers designed for temperature regulation has attracted great attention.

[0003] Traditional phase-change textiles primarily utilize strategies such as surface modification with phase-change media, impregnation with porous materials, and microencapsulation. While these materials can effectively control temperature to a certain extent, they also have some drawbacks. For example, surface modification with phase-change materials can easily leak and exhibit unstable performance under high-temperature conditions. While porous material impregnation offers good stability at high temperatures, its temperature control capability is closely related to the internal phase-change media loading; a larger loading can easily lead to a decrease in the material's mechanical properties. While these preparation methods have already played a significant role in practical thermal management, the low thermal conductivity of most polymer-based materials limits the thermal management capabilities of phase-change fibers. Therefore, the search for simple, efficient, highly conductive phase-change fibers suitable for thermal management in various environments is of great practical significance. In recent years, biomass materials have attracted increasing attention due to their widespread availability, low cost, and environmental friendliness. Cellulose, as a major component of plant cells, is an important renewable resource. Cellulose-based materials hold great potential for the preparation of phase-change fibers, primarily due to their excellent physical and chemical properties and environmental advantages.

[0004] Cellulose-based biomass phase-change fibers have the following advantages: Cellulose and its derivatives, including viscose and Lyocell fibers, are used in the textile industry and advanced functional fibers because of their good renewability, sustainability, hygroscopicity, and breathability. A Chinese patent application numbered 202310878877.X, titled "An Elastic Phase-Change Fiber and Its Preparation Method," states that the prepared elastic phase-change fibers need to be freeze-dried after curing and molding. During the freeze-drying molding process, a large number of pores appear inside the fibers, which blocks heat transfer. As a result, the prepared phase-change fibers have poor thermal conductivity, limiting their application. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a cellulose-based high thermal conductivity phase change fiber and a preparation method thereof. The preparation method is simple, and the wet-spun cellulose fiber is further activated, and the cellulose, phase change medium and high thermal conductivity component BNNs-OH are assembled into a phase change fiber material through a one-step coaxial wet spinning method. The phase change fiber material has good thermal management performance and excellent thermal conductivity. As a thermal management fabric, it is composed of biomass components, can be prepared in one step, has mild conditions, strong operability, high production efficiency, and is suitable for large-scale production and application.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a cellulose-based high thermal conductivity phase change fiber comprises the following steps:

[0008] S1, activating cellulose to obtain cellulose with reduced intermolecular hydrogen bond entanglement;

[0009] S2, dissolving hydroxylated boron nitride nanosheets and the cellulose obtained in S1 in a solvent, wherein the hydroxylated boron nitride nanosheets account for 5% to 50% of the mass of the cellulose, to obtain a shell spinning solution;

[0010] emulsifying hydroxylated boron nitride nanosheets, nanocellulose and phase change medium in deionized water to obtain a core spinning solution;

[0011] S3, spinning the shell layer spinning solution and the core layer spinning solution by a coaxial wet spinning one-step method, wherein the stretching ratio is 100%-350%, to obtain a cellulose-based high thermal conductivity phase change fiber.

[0012] Preferably, S1 activates cellulose in an activator at 80-160° C. for 30-120 min at a mass ratio of 1:10, wherein the activator is N,N-dimethylformamide, N,N-dimethylacetamide or a 20% by mass sodium hydroxide solution, and then dries to obtain cellulose with reduced intermolecular hydrogen bond entanglement.

[0013] Preferably, the hydroxylated boron nitride nanosheets in S2 are obtained by the following process:

[0014] Boron nitride nanosheets are hydrothermally reacted in a sodium hydroxide solution with a concentration of 0.5-1.5 mol / L for 12-36 hours. The ratio of boron nitride nanosheets to sodium hydroxide is (6-10) g: (0.05-0.15) mol. The temperature of the sodium hydroxide solution is 80-120°C. The resulting reaction solution is then centrifuged, washed, and finally dried to obtain hydroxylated boron nitride nanosheets.

[0015] Preferably, the solvent described in S2 is a 78%-84% by mass NMMO aqueous solution, an 8% by mass LiCl N,N-dimethylacetamide solution, or a mixed solution of sodium hydroxide and urea.

[0016] Furthermore, the mass ratio of cellulose obtained by S1 to the solvent was 1:20. When the solvent was a mixed solution of sodium hydroxide and urea, the hydroxylated boron nitride nanosheets and the cellulose obtained by S1 were stirred in the solvent at 55-65°C for 12-24 h to obtain a shell spinning solution.

[0017] When the solvent is a 78%-84% by mass NMMO aqueous solution or an 8% by mass LiCl N,N-dimethylacetamide solution, the hydroxylated boron nitride nanosheets and the cellulose obtained by S1 are stirred in the solvent at room temperature for 12-24 h to obtain a shell spinning solution.

[0018] Preferably, in S2, the mass ratio of hydroxylated boron nitride nanosheets, nanocellulose, phase change medium and deionized water is (0.1-1): (0.5-5): (40-80): (10-57).

[0019] Furthermore, the nanocellulose is TEMPO-CNF, and the phase change medium is paraffin or polyethylene glycol with a molecular weight of 1000-20000.

[0020] Preferably, in S3, the volume ratio of the shell layer spinning solution to the core layer spinning solution is 1:1, the flow rate of the core layer spinning solution is 2-20 ml / h, and the flow rate of the shell layer spinning solution is 5-50 ml / h.

[0021] Furthermore, the coagulation bath used in the one-step coaxial wet spinning method is water, ethanol solution or calcium chloride solution.

[0022] A cellulose-based high thermal conductivity phase change fiber obtained by any of the above-mentioned preparation methods of cellulose-based high thermal conductivity phase change fibers can exhibit phase change ability at 20°C-60°C and has a thermal conductivity of 0.5-10 W / (m·K).

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] The present invention discloses a method for preparing cellulose-based high thermal conductivity phase change fibers. After cellulose is activated, the degree of hydrogen bond entanglement between its molecules is reduced, which can further improve the solubility of cellulose in solvents. The cellulose can then be combined with hydroxylated boron nitride nanosheets (BNNs-OH) to prepare a shell spinning solution. The addition of BNNs-OH as a high thermal conductivity filler at an amount less than 5% cannot achieve a significant improvement in the thermal conductivity coefficient. When the amount exceeds 50%, a large amount of thermal conductive filler will increase the viscosity of the spinning solution, aggregate the thermal conductive filler, and cannot be completely dispersed, resulting in a decrease in the thermal conductivity coefficient. The molecular structure of nanocellulose contains A large number of hydroxyl groups and other active groups can induce the orientation of the thermal conductive filler by forming hydrogen bonds with the high thermal conductive filler. The core layer spinning solution is prepared by deionized water, which can reduce the viscosity of the core layer spinning solution. The shell layer spinning solution and the core layer spinning solution are coaxially wet-spinned in one step to prepare cellulose-based high thermal conductive phase change fibers. The fiber diameter is different under different stretching ratios. As the tensile force increases, the fiber diameter becomes thinner. The fiber interior is subjected to axial tensile force. Under the action of hydrogen bonds, the BNNS-OH in the shell and core layer lamellar state moves with the cellulose and CNF chain segments and is arranged horizontally along the axial direction. The larger the stretch ratio, the more regular the arrangement. However, if the stretch ratio exceeds 300%, a certain degree of defects will appear on the fiber surface. If it continues to increase to 350%, it will cause the phase change medium to leak. The raw material source of the present invention, biomass raw material cellulose, is easily available, abundant and cheap. The degradation products of cellulose-based phase change fibers in the environment are harmless to the environment, in line with the concept of environmental protection. High thermal conductive phase change fibers can be industrialized and have significant benefits.

[0025] When the phase-change fiber of this invention is made into a fabric and applied to the arm, in a 40°C environment, the phase-change medium can transform from solid to liquid, absorbing heat and reducing skin temperature by more than 4°C within 60 seconds. Furthermore, in environments below 20°C, the phase-change medium can transform from liquid back into solid, releasing heat and maintaining skin temperature around 37°C for more than 10 minutes. This fiber exhibits excellent high-temperature thermal conductivity and thermal management properties, enabling stable use in a wide range of environments (e.g., between -10°C and 80°C). As a fiber material, it has a high biomass content, is easily degradable, and is easy to handle, providing a more sustainable option for temperature protection and thermal management. The cellulose-based high-thermal-conductivity phase-change fiber of this invention can withstand temperatures ranging from 20°C to 80°C and maintain stability, exhibiting phase-change properties between 20°C and 60°C, and possessing a thermal conductivity of 0.5-10 W / (m·K). It is an environmentally friendly, efficient, and reliable alternative and will play an important role in the field of phase-change fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a sample photo of the cellulose-based high thermal conductivity phase change fiber prepared in Example 1 of the present invention.

[0027] Figure 2 This is a scanning electron microscope image of the cellulose-based high thermal conductivity phase change fiber prepared in Example 4 of the present invention.

[0028] Figure 3 This is an infrared imaging photograph of the cellulose-based high thermal conductivity phase change fiber fabric prepared in Example 5 of the present invention during the thermal management process. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solution of the present invention with reference to specific drawings, process steps, implementation conditions, and materials. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0030] The present invention provides a method for preparing a cellulose-based high thermal conductivity phase change fiber, comprising the following steps:

[0031] 1) The cellulose is activated (activated in an activator and then dried, with the mass ratio of activator to cellulose being 10:1) to reduce the degree of hydrogen bond entanglement between cellulose molecules and further improve the solubility of cellulose in solvents.

[0032] The activation agent used in the activation process is one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and a 20% by mass sodium hydroxide solution. The activation temperature is 80-160°C, and the activation time is 30-120 minutes.

[0033] 2) Boron nitride nanosheets (BNNs), a high thermal conductivity material, were prepared by hydrothermal reaction to prepare hydroxylated boron nitride nanosheets (BNNs-OH).

[0034] The solvent used for the hydrothermal reaction is sodium hydroxide aqueous solution with a concentration of 0.5-1.5 mol / L, the ratio of BNNs to sodium hydroxide aqueous solution is 6-10 g:100 ml, the reaction temperature is 80-120°C, and the reaction time is 12-36 h. The resulting reaction solution is then centrifuged, washed, and finally dried to obtain BNNs-OH.

[0035] 3) Dissolve BNNs-OH and activated cellulose in 20 g of solvent (corresponding to 1 g of activated cellulose) to prepare a shell spinning solution.

[0036] The solvent is a mixed solution of 78%-84% by mass of NMMO (N-methylmorpholine-N-oxide) aqueous solution, 8% by mass of LiCl in N,N-dimethylacetamide (DMAc) solution, sodium hydroxide and urea, and the stirring time is 12-24 h.

[0037] LiCl in DMAc solution is preferred. Although NNMO aqueous solution is environmentally friendly and controllable, it requires strict process control to prevent explosion. The mixed solution of sodium hydroxide and urea has some obstacles to the dispersion of high thermal conductive fillers and needs to be stirred at 55-65°C, so the operation is relatively troublesome (other solvents are at room temperature).

[0038] Based on the thermal conductivity requirements, the BNNs-OH addition level is 5-50% of the cellulose mass. As the BNNs-OH addition level reaches 50%, the fiber's thermal conductivity reaches its maximum. Further increases in the BNNs-OH addition level decrease the thermal conductivity of the fiber. This is primarily due to the fact that excessive amounts of thermally conductive fillers increase the viscosity of the spinning solution, causing the fillers to aggregate and become unable to disperse completely, leading to a decrease in thermal conductivity.

[0039] 4) Prepare the core spinning solution by mixing BNNs-OH with nanocellulose (CNF), a phase change medium, and deionized water in a mass ratio of (0.1-1):(0.5-5):(40-80):(10-57) and emulsifying (stirring at 90°C for 30 minutes and cooling to room temperature). Under the action of CNF, paraffin wax and CNF segments encapsulate to form phase change microspheres. The hydroxyl groups on the outer CNF layer are hydrogen-bonded with those on the BNNS-OH. If the phase change medium is replaced with PEG, all three contain hydroxyl groups, which are randomly bonded together by hydrogen bonds. Dispersing and emulsifying in water primarily reduces the viscosity of the core spinning solution.

[0040] The CNF is TEMPO-CNF, and the phase change medium is paraffin wax with different phase transition temperatures, which ultimately forms dispersed particles in water, or PEG (polyethylene glycol) with various molecular weights (1,000-20,000). The appropriate phase change material is selected based on specific requirements. The amount of BNNs-OH is determined by the required heat transfer rate. The higher the heat transfer rate, the closer the required BNNs-OH amount is to 70% of the maximum value.

[0041] 5) High thermal conductivity phase change fibers were prepared by a one-step coaxial wet spinning process using a shell spinning solution and a core spinning solution with a volume ratio of 1:1.

[0042] The spinning process parameters are: a core layer spinning solution flow rate of 2-20 ml / h, and a shell layer spinning solution flow rate of 5-50 ml / h. The stretch ratio during spinning is 100-350%, preferably 300%. The spinning coagulation bath is a solution of water, an aqueous ethanol solution, or an aqueous calcium chloride solution. Fiber diameters vary under different stretch ratios. As the stretching force increases, the fiber diameter becomes thinner. The fiber interior is subjected to axial stretching force. Under the action of hydrogen bonds, the lamellar BNNS-OH groups in the shell and core layers move with the cellulose and CNF chain segments, forming a horizontal arrangement along the axial direction. A larger stretch ratio results in a more regular arrangement. However, if the stretch ratio exceeds 300%, a certain degree of defects will appear on the fiber surface. Further increase to 350% will lead to leakage of the phase change medium.

[0043] Example 1

[0044] Take 100g of DMF, add 10g of cellulose into it, activate at 80℃ for 1h, and dry to obtain activated fibers.

[0045] 10 g of BNNs were added to 100 ml of 1 mol / L sodium hydroxide solution and reacted at 100 °C for 20 h. The resulting reaction solution was centrifuged, washed, and finally dried to obtain BNNs-OH.

[0046] Then, 1 g of activated cellulose and 0.5 g of BNNs-OH were added to a 20 g LiCl DMAc solution (the amount of LiCl used was 1.6 g) and stirred at room temperature for 12 h to obtain a shell spinning solution.

[0047] Take 0.1g BNNs-OH, 0.2g TEMPO-CNF, 6g paraffin with a phase transition temperature of 37℃ and 3.7g water, stir at 90℃ for 30 min, and cool to room temperature to obtain the core layer spinning solution.

[0048] Take 10 ml of core layer spinning solution and 10 ml of shell layer spinning solution, add them into a 10 ml syringe, and prepare high thermal conductivity phase change fiber by coaxial wet spinning. The core liquid flow rate is 6 ml / h, the shell layer flow rate is 10 ml / h, the coagulation bath is water, and the stretching ratio is 300%. Cellulose-based high thermal conductivity phase change fiber can be obtained.

[0049] Example 2

[0050] Take 100g of 20% by mass sodium hydroxide, add 10g of cellulose thereto, activate at 80°C for 90 minutes, and dry to obtain activated fibers.

[0051] 10 g of BNNs were added to 100 ml of 0.5 mol / L sodium hydroxide solution and reacted at 120 °C for 36 h. The resulting reaction solution was then centrifuged, washed, and finally dried to obtain BNNs-OH.

[0052] Then, 1 g of activated cellulose and 0.5 g of BNNs-OH were added to a mixed solution of 20 g of urea and sodium hydroxide (the mass ratio of NaOH, urea, and water was 7:12:81), and stirred at 60°C for 12 h to obtain a shell spinning solution.

[0053] Take 0.1g BNNs-OH, 0.2g TEMPO-CNF, 4g PEG with a molecular weight of 12000 and 5.7g water, stir at 90℃ for 30 min, and cool to room temperature to obtain the core layer spinning solution.

[0054] 10 ml of core layer spinning solution and shell layer spinning solution were taken respectively, added into a 10 ml syringe, and high thermal conductivity phase change fiber was prepared by coaxial wet spinning. The core liquid flow rate was 16 ml / h, the shell layer flow rate was 30 ml / h, the coagulation bath was 75% by mass ethanol aqueous solution, and the stretching ratio was 150%. Cellulose-based high thermal conductivity phase change fiber was obtained.

[0055] Example 3

[0056] Take 100g of DMAc, add 10g of cellulose into it, activate at 120℃ for 30min, and dry to obtain activated fiber.

[0057] 10 g of BNNs were added to 100 ml of 0.5 mol / L sodium hydroxide solution and reacted at 80 °C for 15 h. The resulting reaction solution was centrifuged, washed, and finally dried to obtain BNNs-OH.

[0058] Then, 1 g of activated cellulose and 0.3 g of BNNs-OH were added to a 20 g LiCl DMAc solution (the amount of LiCl used was 1.6 g), and stirred at room temperature for 12 h to obtain a shell spinning solution.

[0059] Take 0.1g BNNs-OH, 0.2g TEMPO-CNF, 5g PEG with a molecular weight of 8000 and 4.7g water, stir at 90℃ for 30 min, and cool to room temperature to obtain the core layer spinning solution.

[0060] Take 10 ml of core layer spinning solution and 10 ml of shell layer spinning solution, add them into a 10 ml syringe, and prepare high thermal conductivity phase change fiber by coaxial wet spinning. The core liquid flow rate is 8 ml / h, the shell layer flow rate is 10 ml / h, the coagulation bath is 70% by mass ethanol aqueous solution, and the stretching ratio is 200%. Cellulose-based high thermal conductivity phase change fiber can be obtained.

[0061] Example 4

[0062] Take 100g of DMAc, add 10g of cellulose into it, activate at 120℃ for 30min, and dry to obtain activated fiber.

[0063] 8 g of BNNs were added to 100 ml of 0.5 mol / L sodium hydroxide solution and reacted at 80°C for 15 h. The resulting reaction solution was then centrifuged, washed, and dried to obtain BNNs-OH.

[0064] Then, 1 g of activated cellulose and 0.3 g of BNNs-OH were added to a 20 g LiCl DMAc solution (the amount of LiCl used was 1.6 g), and stirred at room temperature for 12 h to obtain a shell spinning solution.

[0065] Take 0.1g BNNs-OH, 0.2g TEMPO-CNF, 5g paraffin with a phase transition temperature of 45℃ and 4.7g water, stir at 90℃ for 30 min, and cool to room temperature to obtain the core layer spinning solution.

[0066] Take 10 ml of core layer spinning solution and 10 ml of shell layer spinning solution, add them into a 10 ml syringe, and prepare high thermal conductivity phase change fiber by coaxial wet spinning. The core liquid flow rate is 8 ml / h, the shell layer flow rate is 10 ml / h, the coagulation bath is 50% by mass ethanol aqueous solution, and the stretching ratio is 200%. Cellulose-based high thermal conductivity phase change fiber can be obtained.

[0067] Example 5

[0068] Take 100g of DMAc, add 10g of cellulose into it, activate at 120℃ for 30min, and dry to obtain activated fiber.

[0069] 6 g of BNNs were added to 100 ml of 0.5 mol / L sodium hydroxide solution and reacted at 100 °C for 15 h. The resulting reaction solution was then centrifuged, washed, and dried to obtain BNNs-OH.

[0070] Then, 1 g of activated cellulose and 0.3 g of BNNs-OH were added to a 20 g LiCl DMAc solution (the amount of LiCl used was 1.6 g), and stirred at room temperature for 12 h to obtain a shell spinning solution.

[0071] Take 0.2g BNNs-OH, 0.2g TEMPO-CNF, 5g paraffin with a phase transition temperature of 60℃ and 4.6g water, stir at 90℃ for 30 min, and cool to room temperature to obtain the core layer spinning solution.

[0072] 15 ml of core layer spinning solution and shell layer spinning solution were taken respectively, added into a 20 ml syringe, and high thermal conductivity phase change fiber was prepared by coaxial wet spinning. The core liquid flow rate was 10 ml / h, the shell layer flow rate was 18 ml / h, the coagulation bath was a 45% by mass ethanol aqueous solution, and the stretching ratio was 300%. Cellulose-based high thermal conductivity phase change fiber was obtained.

[0073] Example 6

[0074] Take 100g of DMF, add 10g of cellulose into it, activate at 120℃ for 120min, and dry to obtain activated fiber.

[0075] 9 g of BNNs were added to 100 ml of 1 mol / L sodium hydroxide solution and reacted at 100 °C for 20 h. The resulting reaction solution was then centrifuged, washed, and dried to obtain BNNs-OH.

[0076] Then, 1 g of activated cellulose and 0.3 g of BNNs-OH were added to a 20 g LiCl DMAc solution (the amount of LiCl used was 1.6 g), and stirred at room temperature for 12 h to obtain a shell spinning solution.

[0077] Take 0.2g BNNs-OH, 0.2g TEMPO-CNF, 5g paraffin with a phase transition temperature of 25℃ and 4.6g water, stir at 90℃ for 30 min, and cool to room temperature to obtain the core layer spinning solution.

[0078] 15 ml of core layer spinning solution and 15 ml of shell layer spinning solution were taken and added to a 20 ml syringe. High thermal conductivity phase change fiber was prepared by coaxial wet spinning. The core liquid flow rate was 9 ml / h, the shell layer flow rate was 20 ml / h, the coagulation bath was ethanol / water solution, and the stretching ratio was 300%. Cellulose-based high thermal conductivity phase change fiber was obtained.

[0079] like Figure 1 As shown, the prepared core-shell phase change fibers are wound on a collecting roller. The prepared fibers have uniform diameters and a certain glossiness on the surface.

[0080] like Figure 2This SEM image of a cross-section of a prepared phase change fiber clearly shows a two-layer structure: a core composed of the phase change medium paraffin and CNF (the wrinkles inside are caused by CNF aggregation). The outer surface of the fiber has a certain degree of roughness. The fiber shell is approximately 50 μm thick.

[0081] The fibers of Example 5 were woven into a fabric. First, the fabric was placed on a 60°C hot plate, and the temperature changes were recorded using an infrared imager. The yellow background in the first column indicates a constant 60°C hot plate temperature. The fabric surface temperature was recorded over time. The second example shows the fabric cooling process. After heating, the fabric was placed on a 20°C stainless steel plate, and the cooling process was recorded over time. The following results are obtained: Figure 3 As shown in the infrared imaging diagram, it can be seen that when the temperature rises, the temperature is 30.9°C in 5s, 32.1°C in 10s, 34.3°C in 30s, 42.3°C in 60s, 50.0°C in 300s, 55.6°C in 600s, and 55.9°C in 900s. When the temperature drops, the temperature is 53.1°C in 5s, 52.0°C in 10s, 50.8°C in 15s, 49.1°C in 30s, 46.0°C in 60s, 32.8°C in 120s, and 26.5°C in 300s. Therefore, it has certain temperature buffering and thermal management capabilities in both hot and cold environments.

Claims

1. A method for preparing a cellulose-based high thermal conductivity phase change fiber, characterized in that: The following steps are involved: S1, activating cellulose to obtain cellulose with reduced intermolecular hydrogen bond entanglement; S2, dissolving hydroxylated boron nitride nanosheets and the cellulose obtained in S1 in a solvent, wherein the hydroxylated boron nitride nanosheets account for 5% to 50% of the mass of the cellulose, to obtain a shell spinning solution; emulsifying hydroxylated boron nitride nanosheets, nanocellulose and a phase change medium in deionized water, wherein the phase change medium is paraffin wax or polyethylene glycol with a molecular weight of 1,000-20,000, to obtain a core layer spinning solution; S3, spinning the shell layer spinning solution and the core layer spinning solution by a coaxial wet spinning one-step method, wherein the stretching ratio is 100%-350%, to obtain a cellulose-based high thermal conductivity phase change fiber.

2. The method for preparing the cellulose-based high thermal conductivity phase change fiber according to claim 1, characterized in that: S1 activates cellulose at a mass ratio of 1:10 in an activator at 80-160°C for 30-120 min. The activator is N,N-dimethylformamide, N,N-dimethylacetamide or a 20% by mass sodium hydroxide solution, and then dries to obtain cellulose with reduced intermolecular hydrogen bond entanglement.

3. The method for preparing the cellulose-based high thermal conductivity phase change fiber according to claim 1, characterized in that: The hydroxylated boron nitride nanosheets described in S2 are obtained by the following process: Boron nitride nanosheets are hydrothermally reacted in a sodium hydroxide solution with a concentration of 0.5-1.5 mol / L for 12-36 hours. The ratio of boron nitride nanosheets to sodium hydroxide is (6-10) g: (0.05-0.15) mol. The temperature of the sodium hydroxide solution is 80-120°C. The resulting reaction solution is then centrifuged, washed, and finally dried to obtain hydroxylated boron nitride nanosheets.

4. The method for preparing the cellulose-based high thermal conductivity phase change fiber according to claim 1, characterized in that: The solvent described in S2 is a 78%-84% by mass NMMO aqueous solution, an 8% by mass LiCl N,N-dimethylacetamide solution, or a mixed solution of sodium hydroxide and urea.

5. The method for preparing the cellulose-based high thermal conductivity phase change fiber according to claim 4, characterized in that: The mass ratio of cellulose obtained by S1 to solvent is 1:

20. When the solvent is a mixed solution of sodium hydroxide and urea, the hydroxylated boron nitride nanosheets and cellulose obtained by S1 are stirred in the solvent at 55-65°C for 12-24 h to obtain a shell spinning solution. When the solvent is a 78%-84% by mass NMMO aqueous solution or an 8% by mass LiCl N,N-dimethylacetamide solution, the hydroxylated boron nitride nanosheets and the cellulose obtained by S1 are stirred in the solvent at room temperature for 12-24 h to obtain a shell spinning solution.

6. The method for preparing the cellulose-based high thermal conductivity phase change fiber according to claim 1, characterized in that: In S2, the mass ratio of hydroxylated boron nitride nanosheets, nanocellulose, phase change medium and deionized water is (0.1-1): (0.5-5): (40-80): (10-57).

7. The method for preparing the cellulose-based high thermal conductivity phase change fiber according to claim 6, characterized in that: The nanocellulose is TEMPO-CNF.

8. The method for preparing the cellulose-based high thermal conductivity phase change fiber according to claim 1, characterized in that: In S3, the volume ratio of the shell layer spinning solution to the core layer spinning solution is 1:1, the flow rate of the core layer spinning solution is 2-20 ml / h, and the flow rate of the shell layer spinning solution is 5-50 ml / h.

9. The method for preparing the cellulose-based high thermal conductivity phase change fiber according to claim 8, characterized in that: The coagulation bath used in the one-step coaxial wet spinning method is water, ethanol solution or calcium chloride solution.

10. A cellulose-based high thermal conductivity phase change fiber obtained by the preparation method of the cellulose-based high thermal conductivity phase change fiber according to any one of claims 1 to 9.

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