Cellulose-based composite phase change fiber as well as preparation method and application thereof
By combining coaxial wet spinning and aqueous coagulation bath, cellulose-based composite phase change fibers are prepared, which solves the problems of leakage, insufficient heat transfer efficiency and insufficient mechanical properties of phase change fibers in the existing technology. It achieves efficient photothermal synergy and phase change heat storage performance, which is suitable for personal thermal management scenarios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING FORESTRY UNIVERSITY
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-12
AI Technical Summary
Existing phase change fibers suffer from problems such as melt leakage, insufficient heat transfer efficiency, performance degradation after recycling, insufficient mechanical properties, and difficulty in achieving photothermal synergy, making it difficult to balance continuous spinning and high phase change enthalpy.
Using coaxial wet spinning technology, a core-shell structure is formed by solvent exchange between the inner and outer spinning solutions. Combined with an aqueous coagulation bath and two-stage solvent replacement, cellulose-based composite phase change fibers are prepared. Through the composite spinning solution of nanocellulose and phase change materials and the outer extrusion of cellulose/photothermal materials, a stable core-shell structure is formed, which improves mechanical properties and photothermal conversion capabilities.
It achieves efficient confinement of phase change materials, maintains the integrity of fiber structure, and combines high phase change performance, good mechanical properties and photothermal function. It also reduces the use of organic solvents and improves the engineering processability and thermal management efficiency of fibers.
Smart Images
Figure CN122013359A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of phase change materials technology, specifically relating to a cellulose-based composite phase change fiber, its preparation method, and its application. Background Technology
[0002] With rising living standards and urbanization, the demand for thermal comfort in personal wearable devices is constantly increasing, and thermal management processes such as heating and cooling often result in high energy consumption. Phase change materials (PCMs) can undergo reversible phase changes during heating and cooling, absorbing or releasing latent heat to achieve thermal energy storage and release, and are widely used in temperature buffering and thermal energy storage. Among them, solid-liquid phase change materials such as paraffin wax, polyethylene glycol, and n-octadecane have advantages such as high latent heat and adjustable phase change temperature range. However, in practical applications, they are still prone to problems such as melt leakage, insufficient heat transfer efficiency, and performance degradation after repeated use, thus limiting their phase change efficiency and long-term stability.
[0003] To achieve the structured utilization of phase change materials and facilitate subsequent processing and integration, PCM is often composited with a polymer matrix to construct a fibrous morphology. In particular, encapsulating PCM within the fiber using a core-shell structure can improve encapsulation stability and reduce leakage risk during continuous molding. Cellulose, being widely available, renewable, and possessing excellent fiber-forming properties, is an important matrix for constructing phase change fibers, stabilizing phase change systems and aiding in encapsulation. However, phase change fibers for engineering applications, in addition to requiring high phase change heat storage capacity, generally prioritize mechanical properties and aim to further incorporate photothermal conversion functions to enhance the efficiency of energy harvesting and utilization. Therefore, developing a cellulose-based composite phase change fiber technology that can balance phase change performance, mechanical properties, and photothermal properties within the fiber structure has significant research and application value.
[0004] Currently, the main methods for preparing phase change fibers include melt spinning, wet spinning, and electrospinning. Melt spinning often requires high processing temperatures, which can easily cause leakage, migration, or thermal aging of the phase change material. While electrospinning is convenient for constructing porous / nanostructures, it generally suffers from low yield, high cost, and difficulty in continuous large-scale preparation. In contrast, wet spinning offers relatively mild process conditions and strong continuous forming capability, and is therefore considered one of the important approaches to achieving the engineering preparation of phase change fibers.
[0005] Currently, the preparation of phase change fibers mainly employs hollow fiber post-impregnation and wet spinning methods. Hollow fiber post-impregnation typically involves first preparing fibers with a hollow structure, then introducing solid-liquid phase change materials into the cavity through melt impregnation or vacuum adsorption to achieve heat storage functionality. This method is highly dependent on the quality of the hollow structure formation and the subsequent impregnation process; continuous production stability and fiber structure consistency are easily affected by process fluctuations. In contrast, wet spinning has stronger continuous forming capabilities and is therefore more widely used in the preparation and scale-up of phase change fibers. In wet spinning processes, existing technologies more commonly employ coaxial wet spinning to form a core-shell structure. The outer layer is a polymer solution that can rapidly solidify during coagulation to form a continuous outer shell, while the inner layer is a feed system containing the phase change material. The feed system can be a microcapsule suspension, emulsion, or dispersion, or it can be a molten phase change material and its modified system. After being coaxially spun, the spinning solution enters the coagulation bath, where the outer layer preferentially solidifies and coats the inner phase change components, thereby obtaining a continuous filament that can be drawn and wound. In the coagulation and post-treatment stages, organic solvents such as ethanol, isopropanol, and acetone, or mixtures thereof, are often used as coagulation or displacement media, along with washing, solvent displacement, and drying and setting steps to reduce residual solvents and stabilize the fiber structure.
[0006] In summary, the shortcomings of the existing technology can be summarized as follows: (1) Solid-liquid phase change materials are prone to leakage: Solid-liquid phase change materials such as paraffin (PW), polyethylene glycol, and n-octadecane will melt and flow during phase change. If the coating / encapsulation is not sufficient, leakage is likely to occur, resulting in fabric contamination, heat storage capacity reduction and service life reduction. Even if conventional coating methods are used, leakage and performance degradation often occur due to shell defects, interface instability or structural damage after cycling. (2) Process defects: Existing phase change fibers often use organic coagulation baths such as ethanol, isopropanol, and acetone or multi-step organic solvent replacement in the solidification and post-processing stages to obtain a denser shell and interface stability. However, such processes are often more complex and may lead to solvent residues, safety, environmental protection and cost burdens, thereby affecting the stability of continuous preparation and engineering scale-up. (3) It is difficult to simultaneously achieve both encapsulation form and textileability: Microcapsule strategies often result in powder or filler-type products, which are more often used as coatings / fillers, which is not conducive to forming continuous filaments and further weaving them into fabrics. Aerogel encapsulation often forms blocks or films, which limits the flexibility of textile processing and wearability. Existing technologies cannot achieve a balance between continuous spinning and high phase change enthalpy / leakage resistance. (4) Insufficient mechanical strength: When the structural design and process coupling are not properly coordinated, phase change fibers are prone to microcracks, interface peeling or loose structure, resulting in a decrease in load-bearing capacity and loss of phase change material, thereby reducing the wearability and safety of the fabric. (5) Difficulty in achieving "light-heat-heat storage" synergy: Some phase change fibers rely solely on ambient heat for phase change heat storage and release, lacking an efficient light-heat conversion interface, resulting in insufficient heating rate and energy utilization under external fields such as solar irradiation, making it difficult to achieve rapid heat charging or active synergy in low-temperature environments. Summary of the Invention
[0007] Technical Purpose
[0008] The technical objective of this invention is to provide a novel cellulose-based composite phase change fiber and its preparation method, which enables the phase change material to achieve efficient confinement and maintain the integrity of the fiber structure under repeated phase change cycles. This significantly suppresses leakage while taking into account high phase change performance, good mechanical properties and photothermal functions. Furthermore, it reduces the dependence on organic solidification media while ensuring the quality of forming and packaging. Preferably, it achieves a controllable forming and post-processing path based on water-based solidification.
[0009] Another technical objective of this invention is to provide articles made from cellulose-based composite phase change fibers.
[0010] Technical content On one hand, the present invention provides a method for preparing cellulose-based composite phase change fibers, the method comprising the following steps: (1) Preparation of cellulose / photothermal material composite spinning solution: The cellulose raw material is completely dissolved in the cellulose solvent, and cellulose auxiliary agent is optionally added. After the cellulose is completely dissolved, the photothermal material is added and the mixture is stirred until it is completely dispersed to obtain the cellulose / photothermal material composite spinning solution. Preparation of nanocellulose / phase change material composite spinning solution: The nanocellulose dispersion in deionized water and the phase change material were thoroughly mixed under stirring to obtain the nanocellulose / phase change material composite spinning solution; (2) Using a spinning solution extrusion device with a coaxial spinning needle having inner and outer layers, the nanocellulose / phase change material composite spinning solution prepared in the previous step is extruded from the inner layer of the coaxial spinning needle, and the cellulose / photothermal material composite spinning solution prepared in the previous step is extruded from the outer layer of the coaxial spinning needle, so that the two spinning solutions are extruded simultaneously. After passing through an air gap of 1-3 cm, they enter the water, and wet composite fibers are obtained through a solvent exchange process; and (3) Place the wet composite fiber prepared in step (2) in water as a coagulation bath and let it stand for 12-24 hours, or change the coagulation bath multiple times, so that the wet composite fiber and the solvent of the coagulation bath can be fully exchanged. Then, dry continuously or dry intermittently in an oven, and finally wind it on a roller to obtain cellulose-based composite phase change fiber.
[0011] In a specific embodiment, in step (1), the cellulose raw material is selected from one or more of dissolved wood pulp, refined cotton, and chemical wood pulp, and the degree of polymerization is 400-1500.
[0012] In a specific embodiment, in step (1), the cellulose solvent is selected from one or more of superbasic ionic liquids, imidazole ionic liquids, pyridinic ionic liquids and choline ionic liquids, preferably 1-allyl-3-methylimidazolium chloride or N-propenylpyridinium chloride.
[0013] In a specific embodiment, in step (1), the cellulose adjuvant is selected from one or more of dimethyl sulfoxide (DMSO) and dimethylformamide (DMF).
[0014] In a specific embodiment, in step (1), the photothermal material is selected from one or more of carbon nanotubes, carbon black and graphene.
[0015] In a specific embodiment, in step (1), the cellulose raw material and cellulose solvent are mixed at a mass ratio of 1:20-30, the mass ratio of cellulose solvent to cellulose auxiliary agent is 5:1-2, and the photothermal material and cellulose raw material are mixed at a mass ratio of 0.1-1:1.
[0016] In a specific embodiment, in step (1), the conditions for dissolving the cellulose raw material are: stirring at 70-100 °C and 100-800 rpm for 1-6 h until the cellulose raw material is completely dissolved in the cellulose solvent.
[0017] In a specific embodiment, in step (1), the nanocellulose is selected from one or more of mechanically processed cellulose nanofibers, TEMPO oxidized cellulose nanofibers, and carboxymethylated cellulose nanofibers.
[0018] In a specific embodiment, in step (1), the phase change material is selected from one or more of paraffin, polyethylene glycol and n-octadecane.
[0019] In a specific embodiment, in step (1), the concentration of the cellulose / photothermal material composite spinning solution is 2-8 wt%, and the concentration of the nanocellulose / phase change material composite spinning solution is 4-24 wt%.
[0020] In a specific embodiment, in step (1), the mass ratio of the phase change material to the nanocellulose is 9-29:1.
[0021] In a specific embodiment, in step (1), the concentration of the nanocellulose dispersion in deionized water is 0.5-1wt%.
[0022] In a specific embodiment, in step (1), the preparation conditions of the nanocellulose / phase change material composite spinning solution are: stirring at 20-100 °C and a speed of 500-8000 rpm for 15 min-1 h to ensure thorough mixing.
[0023] In a specific implementation, in step (2), the coaxial spinning needle with inner and outer double layers is one of 12G, 13G, 14G, 15G, 16G, 17G, 18G, 19G, 20G, 21G, 22G, 23G, 24G, 25G, 26G, 27G, 28G, 30G, and 32G. The specifications of the inner and outer needles can be selected according to the fiber diameter required for actual production and the ratio of the inner and outer diameters.
[0024] In a specific embodiment, in step (2), the spinning solution extrusion equipment is also equipped with a feed cylinder.
[0025] In a specific embodiment, in step (2), the outer layer extrusion temperature is 70-100 °C. The temperature can be controlled using a temperature control device on the barrel.
[0026] In a specific embodiment, in step (2), the injection speed is controlled by air pressure, and the extrusion speed is 0.02-0.45 ml / min. The extrusion speed of the inner and outer layers is selected according to the solid content of different spinning solutions. For example, for a cellulose / photothermal material composite spinning solution, a solid content of 3 wt% corresponds to an extrusion speed of 0.2 ml / min, and so on, 4 wt% corresponds to 0.25 ml / min, 5 wt% corresponds to 0.3 ml / min, 6 wt% corresponds to 0.35 ml / min, 7 wt% corresponds to 0.4 ml / min, and 8 wt% corresponds to 0.45 ml / min. For a nanocellulose / phase change material composite spinning solution, a solid content of 5 wt% corresponds to an extrusion speed of 0.02 ml / min, and so on, 10 wt% corresponds to 0.03 ml / min, 15 wt% corresponds to 0.04 ml / min, 20 wt% corresponds to 0.05 ml / min, and 25 wt% corresponds to 0.06 ml / min. In a specific implementation, in step (2), the air gap is 1-3 cm.
[0027] In step (2), the two-step solvent exchange mechanism in coaxial wet spinning is as follows: the inner layer of nanocellulose / phase change material composite spinning solution is an aqueous phase, and the outer layer of cellulose / photothermal material composite spinning solution is an organic phase. To ensure that the fiber can be formed in the coagulation bath, water is chosen as the coagulation bath. In summary, the fiber center and the surrounding medium together constitute a three-phase system of inner aqueous phase – outer organic phase – coagulation bath aqueous phase. The inner and outer spinning solutions are simultaneously extruded from the coaxial spinning needle and enter the air gap. During this period, solvent exchange occurs between the aqueous solvent of the inner layer and the organic solvent of the outer layer, which is the first-stage solvent exchange. The inner and outer spinning solutions enter the water serving as the coagulation bath, where the cellulose solvent, cellulose auxiliaries, and coagulation bath undergo rapid bidirectional diffusion, completing the cellulose coagulation and regeneration, which is the second-stage solvent exchange. This process is accompanied by the synchronous migration of cellulose solvent, cellulose auxiliaries, and water in the inner and outer layers of the fiber, which enhances the stability of the fiber's inner and outer interfaces, ultimately forming a cellulose-based composite phase change fiber with a core-shell structure. It is this two-stage solvent exchange process of "air gap-water bath" that enables the outer cellulose to achieve a continuous structure during regeneration and forms a strong coupling at the core-shell interface, thereby significantly improving the fiber's mechanical strength and structural integrity. At the same time, the stable core-shell confinement effectively suppresses the leakage of phase change components and maintains its reversible phase change behavior, ensuring high phase change enthalpy and cycle stability, ultimately endowing the fiber with excellent mechanical properties and phase change heat storage performance.
[0028] On the other hand, the present invention provides a cellulose-based composite phase change fiber prepared by the above method.
[0029] In a specific embodiment, the cellulose-based composite phase change fiber has a core-shell structure, wherein the shell is cellulose / photothermal material and the core is nanocellulose / phase change material. The shell thickness is approximately 20 μm, and the core thickness is approximately 720 μm. The phase change enthalpy is as high as 142.69 J / g, and the latent heat retention rate is 84.01%. After 75 thermal cycles, it still retains 71.7% of its initial latent heat capacity. Thanks to the coaxial orientation structure of the fiber and the strong core-shell interface bonding, its tensile strength can reach 47.94 MPa, and it can be directly woven into fabric. After introducing the photothermal material, based on the photothermal shell and the microtexture structure of the fiber surface, the fabric made from this fiber has a tensile strength of 125 mW / cm². 2 Under certain lighting conditions, the photothermal conversion efficiency can reach up to 84.11%.
[0030] In another aspect, the present invention provides a thermal management article comprising at least the above-mentioned cellulose-based composite phase change fiber.
[0031] In a specific embodiment, the article is a fabric.
[0032] In a specific embodiment, the fabric is woven from the aforementioned cellulose-based composite phase change fibers.
[0033] Furthermore, the present invention provides the application of the above-mentioned thermal management product in research on human body temperature regulation.
[0034] Beneficial effects The cellulose-based composite phase change fiber of this invention achieves structural confinement of solid-liquid phase change materials through a core-shell structure. The core layer consists of cellulose and phase change components forming a thermal storage unit, while the shell layer consists of a cellulose-based composite photothermal material forming an outer shell. This is achieved through a two-stage solvent replacement and aqueous solidification process, which, combined with the two-step solvent replacement process, creates a micro-textured morphology on the fiber surface. This ensures both phase change thermal storage functionality and high mechanical strength and photothermal conversion capability. This structure provides the phase change material with dual constraints of "interface stability + shell confinement" during melting / solidification cycles, effectively reducing the risk of leakage and cycle decay. The introduction of the photothermal material significantly improves the fiber's thermal conductivity and light absorption capacity, promoting rapid heat charging and discharging and achieving more efficient photo-thermal-phase change thermal storage synergistic temperature regulation under illumination.
[0035] This invention employs coaxial wet spinning to achieve continuous fiber formation. Compared to methods that primarily yield powder / filler through microcapsule or porous carrier adsorption, this approach is more suitable for continuous preparation, improving engineering processability and application adaptability. In terms of process, this invention uses water as a coagulation bath and combines it with two-stage solvent replacement to achieve structural control. Compared to common organic coagulation baths or multi-step organic replacement routes, this reduces the safety and environmental burden caused by the use and residue of organic media, and improves the stability and scalability of the continuous preparation process. Photothermal materials enhance the fiber's absorption and thermal conversion of light energy, and couple heat to the core-layer phase change unit more quickly through shell thermal conduction. The micro-textured surface formed by the two-step solvent replacement further enhances light absorption and heat exchange, promoting the synergistic effect of photothermal acquisition and phase change heat storage. Ultimately, this results in a thermal management fabric that combines leak-proofness, fast response, high strength, and photothermal enhancement, suitable for personal thermal management and related thermal control scenarios. Attached Figure Description
[0036] Figure 1 : Morphology-cross section SEM image of the cellulose-based composite phase change fiber prepared in Example 1 of this invention.
[0037] Figure 2 : Morphology-side surface SEM image of the cellulose-based composite phase change fiber prepared in Example 1 of this invention.
[0038] Figure 3 : DSC heating and cooling curves of cellulose-based composite phase change fibers and paraffin prepared in Examples 1-3 of this invention.
[0039] Figure 4 : DSC heating and cooling cycle curve of cellulose-based composite phase change fiber prepared in Example 2 of this invention.
[0040] Figure 5 Image showing the cellulose-based composite phase change fiber prepared in Example 4 of this invention, weighed at 200 g.
[0041] Figure 6 Image of a fabric woven from the cellulose-based composite phase change fiber prepared in Example 5 of this invention.
[0042] Figure 7 : Encapsulation test diagrams of cellulose-based composite phase change fibers prepared in Examples 1-3 and Comparative Example 1 of this invention.
[0043] Figure 8 Tensile stress-strain curves of cellulose-based composite phase change fibers prepared in Examples 1-3 and fibers prepared in Comparative Example 3.
[0044] Figure 9The graph shows the heating curves of the cellulose-based composite phase change fibers prepared in Examples 1-3 of this invention and the cooling curves of the fibers prepared in Comparative Example 3 under light irradiation and after the light source is turned off.
[0045] Figure 10 Temperature rise and fall curves of fabrics woven from cellulose-based composite phase change fibers prepared in Example 2 of the present invention, fabrics woven from fibers prepared in Comparative Example 3, and commercial fabrics at 85 °C and 25 °C. Detailed Implementation
[0046] The technical solutions of this application will be described in detail below through embodiments to enable those skilled in the art to better understand this application; however, the provision of these embodiments is not intended to limit the scope of this application.
[0047] the term In this article, "thermal management" refers to the use of cellulose-based composite phase change fibers as the core, which accelerates the heat storage and release response rate of the fibers through the synergistic effect of solar photothermal conversion and phase change heat storage, thereby enhancing their ability to buffer and regulate environmental or human body temperature fluctuations.
[0048] Materials, reagents, and instruments Materials: Refined cotton (DP=600) and chemical wood pulp (DP=1000) were purchased from Jinan Shengquan Group Co., Ltd. (Jinan, China); dissolving wood pulp (DP=700) was purchased from Hubei Chemical Fiber Co., Ltd.; carbon nanotubes, carbon black, and graphene were purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.; ionic liquid 1-allyl-3-methylimidazolium chloride ([AMIM]Cl, 421.66) was purchased from Qingdao Aolico New Materials Technology Co., Ltd. (China); dimethyl sulfoxide (DMSO, 78.13) and dimethylformamide (DMF) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd. All reagents were used directly without further purification. Polyethylene glycol (PEG, Mn=2000) was purchased from Beijing Lanyi Co., Ltd., China. Paraffin wax (PW, Mn=341.4) and n-octadecane were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Mechanically processed cellulose nanofibers, TEMPO oxidized cellulose nanofibers, and carboxymethylated cellulose nanofibers were purchased from Tianjin Wood Elf Biotechnology Co., Ltd.
[0049] Instrumentation: The microstructure of the fibers was characterized using a scanning electron microscope (SEM, Hitachi SU-8010), and the thermal properties of the fibers were tested using a differential scanning calorimeter (DSC, TA2500). The latent heat retention rate was calculated according to Formula 1.
[0050] In the formula, ΔH m1 ΔH represents the enthalpy of heating of paraffin (PW).m2 The enthalpy value for heating cellulose-based composite phase change fibers.
[0051] The mechanical properties of the samples were tested using a tensile testing machine (Zwell, Roell), and a xenon lamp (CEL-HXUV300) was used to simulate sunlight of different intensities (125 mW / cm²). 2 Thermocouples were connected to a computer to record temperature changes in the fibers, thereby evaluating their photothermal conversion efficiency. Simultaneously, an infrared thermal imager (Fotric, 325pro) was used to acquire infrared thermal images of the samples, recording temperature changes in different fabrics. The photothermal conversion efficiency was calculated using Formula 2:
[0052] In the formula, m is the sample mass (g), and ΔH h enthalpy of temperature rise of cellulose-based composite phase change fiber (J / g), P is solar irradiance (mW / cm²). 2 ), s is the irradiated area of the sample (cm²) 2 ), Δt is the phase transition duration (s); all of the above parameters are key parameters for evaluating the photothermal conversion performance of phase change materials.
[0053] Preparation Example Example 1: (S1) Preparation of spinning solution: (S1-1) Preparation of cellulose / photothermal material composite spinning solution: First, refined cotton and 1-allyl-3-methylimidazolium chloride were mixed at a mass ratio of 1:25, and dimethyl sulfoxide (DMSO) was added at a mass ratio of 1-allyl-3-methylimidazolium chloride to dimethyl sulfoxide of 5:1. The mixture was dissolved at 80 °C and 200 rpm for 4 h to ensure complete dissolution of the cellulose. Subsequently, carbon nanotubes were added at a mass ratio of cellulose to photothermal material of 1:0.5, and the mixture was stirred for another 2 h at 80 °C and 200 rpm, successfully preparing a 5% cellulose / photothermal material composite spinning solution.
[0054] (S1-2) Preparation of nanocellulose / phase change material composite spinning solution: TEMPO oxidized cellulose nanofibers were added to deionized water to prepare a nanocellulose dispersion with a concentration of 0.7%. Paraffin was added at a mass ratio of paraffin to TEMPO oxidized cellulose nanofibers of 20:1. The mixture was thoroughly mixed for 15 min at 80 °C and 8000 rpm, and a nanocellulose / phase change material composite spinning solution with a concentration of 13% was successfully prepared.
[0055] (S2) Wet spinning: Wet spinning is performed using a spinning solution extrusion device equipped with a barrel and coaxial spinning needles (inner and outer double layers). The cellulose / photothermal material composite spinning solution prepared in step (S1-1) is used as the outer layer, and the nanocellulose / phase change material composite spinning solution prepared in step (S1-2) is used as the inner layer. The inner and outer coaxial spinning needles are 21G and 16G respectively. The spinning rates of the inner and outer layers are 0.03 ml / min and 0.27 ml / min respectively. The temperature of the outer layer is controlled at 80 °C using the barrel's temperature control device, so that the inner and outer spinning solutions are extruded simultaneously. The spinning needles are 1 cm away from the surface of the water coagulation bath. After passing through an air gap, the fibers enter the coagulation bath to obtain wet composite fibers.
[0056] (S3) Solvent exchange and drying: The wet composite fiber obtained in step (S2) is moved through a water coagulation bath to allow for sufficient solvent exchange between the wet composite fiber and the solvent in the coagulation bath for 24 hours to remove residual cellulose solvent and auxiliary molecules. Then, it is continuously dried in air and finally wound onto a wire roller to obtain cellulose / phase change material composite thermal management fiber.
[0057] Example 2: (S1) The preparation of the spinning solution was the same as in Example 1, except that paraffin was added at a mass ratio of paraffin:TEMPO oxidized cellulose nanofibers of 15:1, and a 10% nanocellulose / phase change material composite spinning solution was successfully prepared.
[0058] (S2, S3) Wet spinning, solvent exchange and drying are exactly the same as in Example 1.
[0059] Example 3: (S1) The preparation of the spinning solution was the same as in Example 1, except that paraffin was added at a mass ratio of paraffin:TEMPO oxidized cellulose nanofibers of 10:1, and a 7% nanocellulose / phase change material composite spinning solution was successfully prepared.
[0060] (S2, S3) Wet spinning, solvent exchange and drying are exactly the same as in Example 1.
[0061] Example 4: (S1) Preparation of spinning solution: (S1-1) Preparation of cellulose / photothermal material composite spinning solution: First, dissolved wood pulp and 1-allyl-3-methylimidazolium chloride were mixed at a mass ratio of 1:25, and dimethylformamide (DMF) was added at a mass ratio of 1-allyl-3-methylimidazolium chloride to dimethylformamide of 5:1. The mixture was dissolved at 90 °C and 200 rpm for 4 h to ensure complete dissolution of the cellulose. Subsequently, carbon nanotubes were added at a mass ratio of cellulose to photothermal material of 1:0.5, and the mixture was stirred for another 2 h at 90 °C and 200 rpm, successfully preparing a 5% cellulose / photothermal material composite spinning solution.
[0062] (S1-2) Preparation of nanocellulose / phase change material composite spinning solution: A nanocellulose dispersion with a concentration of 0.7% was prepared by adding mechanically produced cellulose nanofibers to deionized water. Polyethylene glycol was added at a mass ratio of 15:1 to mechanically produced cellulose nanofibers, and the mixture was thoroughly mixed for 20 min at 25 °C and 500 rpm, thus successfully preparing a 10% nanocellulose / phase change material composite spinning solution.
[0063] (S2) Wet spinning: Wet spinning is performed using a spinning solution extrusion device equipped with a barrel and coaxial spinning needles (inner and outer layers). The cellulose / photothermal material composite spinning solution prepared in step (S1-1) is used as the outer layer, and the nanocellulose / phase change material composite spinning solution prepared in step (S1-2) is used as the inner layer. The inner and outer coaxial spinning needles are 22G and 17G respectively. The spinning rates of the inner and outer layers are 0.06 ml / min and 0.30 ml / min respectively. The temperature of the outer layer is controlled at 90 °C using the barrel's temperature control device, so that the inner and outer spinning solutions are extruded simultaneously. The spinning needles are 2 cm away from the surface of the water coagulation bath. After passing through an air gap, the fibers enter the water coagulation bath to obtain wet composite fibers.
[0064] (S3) Solvent exchange and drying: The wet composite fiber obtained in step (S2) is moved through a water coagulation bath to allow for sufficient solvent exchange between the wet composite fiber and the solvent in the coagulation bath for 24 hours, in order to remove residual cellulose solvent and auxiliary molecules. Then, it is continuously dried in air and finally wound onto a wire roller to obtain cellulose / phase change material composite thermal management fiber.
[0065] Example 5: (S1) Preparation of spinning solution: (S1-1) Preparation of cellulose / photothermal material composite spinning solution: First, chemical wood pulp with a degree of polymerization of 800 and N-propenylpyridine chloride were mixed at a mass ratio of 1:25, and dimethylformamide was added at a mass ratio of N-propenylpyridine chloride to dimethylformamide of 5:1. The mixture was dissolved at 70 °C and 200 rpm for 4 h to ensure complete dissolution of the cellulose. Subsequently, graphene was added at a mass ratio of cellulose to photothermal material of 1:0.5, and the mixture was stirred for another 2 h at 70 °C and 200 rpm, successfully preparing a 5% cellulose / photothermal material composite spinning solution.
[0066] (S1-2) Preparation of nanocellulose / phase change material composite spinning solution: A nanocellulose dispersion with a concentration of 0.7% was prepared by adding carboxymethyl cellulose nanofibers to deionized water. Polyethylene glycol was added at a mass ratio of 15:1 to cellulose nanofibers, and the mixture was thoroughly mixed for 20 min at 25 °C and 500 rpm, thus successfully preparing a 10% nanocellulose / phase change material composite spinning solution.
[0067] (S2) Wet spinning: Wet spinning is performed using a spinning solution extrusion device equipped with a barrel and coaxial spinning needles (inner and outer layers). The cellulose / photothermal material composite spinning solution prepared in step (S1-1) is used as the outer layer, and the nanocellulose / phase change material composite spinning solution prepared in step (S1-2) is used as the inner layer. The inner and outer coaxial spinning needles are 22G and 17G respectively, and the spinning rates of the inner and outer layers are 0.1 ml / min and 0.36 ml / min respectively, to stabilize the fiber structure and prevent collapse. The temperature of the outer layer is controlled at 70 °C using the barrel's temperature control device, allowing the inner and outer spinning solutions to be extruded simultaneously. The spinning needles are 3 cm away from the surface of the water coagulation bath, and the fibers enter the water coagulation bath after passing through an air gap.
[0068] (S3) Solvent exchange and drying are exactly the same as in Example 4.
[0069] Comparative Example 1: (S1) The preparation of the spinning solution was the same as in Example 1, except that paraffin was added at a mass ratio of 25:1 of paraffin:TEMPO oxidized cellulose nanofibers, and a 15% nanocellulose / phase change material composite spinning solution was successfully prepared.
[0070] (S2, S3) Wet spinning, solvent exchange and drying are exactly the same as in Example 1.
[0071] Comparative Example 2: (S1) Preparation of spinning solution: TEMPO oxidized cellulose nanofibers were added to deionized water to prepare a nanocellulose dispersion with a concentration of 0.7%. Paraffin was added at a mass ratio of 15:1 of paraffin to TEMPO oxidized cellulose nanofibers, and the mixture was thoroughly mixed for 15 min at 80 °C and 8000 rpm. Finally, a 10% nanocellulose / phase change material composite spinning solution was successfully prepared.
[0072] (S2) Wet spinning: Wet spinning was performed using a spinning solution extrusion device equipped with a barrel and spinning needles, using the nanocellulose / phase change material composite spinning solution prepared in step (S1). The spinning needles were 17G, the spinning rate of the injection pump was 0.03 ml / min, and the spinning needles were inserted 1 cm below the surface of the water coagulation bath.
[0073] Experiments revealed that the cellulose / phase change material composite spinning solution in Comparative Example 2 exhibited strong fluidity but lacked fiber-forming properties, making wet spinning difficult. This underscores the importance of shell design for constructing phase change material composite thermal management fibers.
[0074] Comparative Example 3: (S1) Preparation of spinning solution: First, refined cotton with a degree of polymerization of 600 and a 1-allyl-3-methylimidazolium chloride solution were mixed at a mass ratio of 1:25 and dissolved at 80 °C and 200 rpm for 4 h to ensure complete dissolution of cellulose. Then, carbon nanotubes were added at a mass ratio of cellulose to photothermal material of 1:0.5, and the mixture was stirred for another 2 h at 80 °C and 200 rpm. Finally, a cellulose / photothermal material composite spinning solution with a concentration of 5.7% was successfully prepared.
[0075] (S2) Wet spinning: Wet spinning is performed using a spinning solution extrusion device equipped with a barrel and spinning needles, using the cellulose / photothermal material composite spinning solution prepared in step (S1). The spinning needles are 17G, and the spinning rate of the injection pump is 0.03 ml / min. The temperature of the barrel is controlled at 80 °C using a temperature control device, and the spinning needles are 1 cm away from the surface of the water coagulation bath. The fibers enter the coagulation bath after passing through an air gap.
[0076] (S3) Solvent exchange and drying: The wet composite fiber obtained in step (S2) is moved through a water coagulation bath to allow the wet composite fiber to undergo sufficient solvent exchange with the solvent in the coagulation bath. Then it is continuously dried in the air and finally wound onto a wire roller to obtain cellulose / photothermal composite fiber.
[0077] Test example: Test Example 1: The cellulose / phase change material composite thermal management fiber prepared in Example 1 was observed by SEM. The results are shown in [Figure 1]. Figure 1 and2 .
[0078] Figure 1 and Figure 2 The cross-sectional SEM images and side-surface SEM images of the cellulose / phase change material composite thermal management fiber prepared in Example 1 are shown. The images clearly show that the interface between the inner and outer layers of the fiber is tightly connected without obvious cracks. The inner layer of the fiber has a solid and dense structure, and the paraffin microcapsules retain their spherical structure after encapsulation. Due to the two-stage solvent exchange during the coaxial wet spinning process, the fiber surface exhibits a micro-textured morphology.
[0079] Test Example 2: Differential scanning calorimetry (DSC) was used to test the endothermic and exothermic properties of the fibers under heating and cooling conditions: an empty crucible was placed in the reference pan, and the crucible containing the weighed sample was placed in the sample pan. The initial equilibrium temperature was 0 °C under a nitrogen atmosphere, and the temperature was increased to 100 °C at a rate of 10 °C / min without holding, and then decreased to 0 °C at a rate of -10 °C / min. Figure 3 The DSC heating and cooling curves of the cellulose-based composite phase change fibers and paraffin in Examples 1-3 are presented. As can be seen from the figures, the fiber in Example 1 has a crystallization peak temperature of 45.6 °C and a crystallization endothermic enthalpy of 135.1 J / g, a melting peak temperature of 56.5 °C, and a melting exothermic enthalpy of 134.1 J / g. The fiber in Example 3 exhibits both endothermic and exothermic peaks, indicating that it possesses the energy storage and temperature regulation capabilities of a phase change material. The fiber in Example 3 has a crystallization peak temperature of 45.8 °C and a crystallization endothermic enthalpy of 112.3 J / g, a melting peak temperature of 56.9 °C, and a melting exothermic enthalpy of 110.2 J / g.
[0080] The comparison revealed that the endothermic and exothermic peaks of the cellulose / phase change material composite thermal management fiber of this application are close to those of paraffin, indicating that the cellulose-based composite phase change fiber of this application has excellent energy storage and temperature regulation capabilities.
[0081] Test Example 3: The DSC heating and cooling cycle curves of the cellulose / phase change material composite thermal management fiber in Example 2 were evaluated, and the results are as follows.
[0082] from Figure 4 It can be seen that after 100 heating and cooling cycles, the heat absorption and release of the fiber hardly changed. After the 75th heating and cooling cycle, it still retained 71.7% of its latent heat capacity, demonstrating the fiber's excellent thermal energy storage stability and the encapsulation effect of the paraffin-based phase change material, which is crucial for intelligent thermally regulated textiles.
[0083] Test Example 4: The mechanical properties of the cellulose-based composite phase change fiber prepared in Example 4 were tested, and the results showed that... Figure 5 middle.
[0084] from Figure 5 As can be seen, the fiber can lift a weight equivalent to 2000 times its own weight (200 g) without breaking, indicating that the excellent mechanical strength of cellulose is well imparted to the cellulose-based composite phase change fiber.
[0085] Test Example 5: The cellulose-based composite phase change fiber prepared in Example 5 was woven into a square fabric of 2 cm × 2.5 cm. Figure 6 This indicates that the cellulose-based composite phase change fiber possesses excellent flexibility and mechanical strength, and can be easily made into fabrics using traditional weaving processes, demonstrating its great potential for widespread application in the field of wearable thermal management.
[0086] Test Example 6: To evaluate the encapsulation effect of the cellulose-based composite phase change fiber of this application on paraffin, pure paraffin, and the fiber samples from Examples 1-3 and Comparative Example 1 were placed on filter paper. After heating at 100 °C for 1 hour, the oil spot diffusion phenomenon on the filter paper surface was observed. The results are as follows: Figure 7 As shown in the image.
[0087] from Figure 7 As can be seen, the unstained oil spots can be clearly observed by adding a hydrophilic methyl orange solution. Almost no white oil spots were observed on the filter paper containing the fibers in Examples 1-3. In contrast, Comparative Example 1 showed obvious traces of paraffin leakage after heating.
[0088] Test Example 7: The mechanical properties of the cellulose-based composite phase change fibers prepared in Examples 1-3 and the cellulose / photothermal composite fiber prepared in Comparative Example 3 were tested. The fibers were clamped in the fixture of a tensile testing machine, ensuring good alignment to prevent eccentric forces from affecting test accuracy. A 10 N sensor was used, and the tensile rate was set to 1 mm / min. A tensile load was applied slowly at a constant rate, while the sensor simultaneously collected data on the load and elongation within the gauge length. The fiber tensile stress-strain results are shown below. Figure 8 middle.
[0089] from Figure 8As can be seen from the data, the tensile breaking stress of the fiber in Example 1 was 32.56 MPa, and the elongation at break was 11.15%. In Example 2, the tensile breaking stress of the fiber was 42.56 MPa, and the elongation at break was 7.78%. In Example 3, the tensile breaking stress of the fiber was 47.94 MPa, and the elongation at break was 9.79%. In contrast, the tensile breaking stress of the cellulose / photothermal composite fiber in Comparative Example 3 was 27.00 MPa, and the elongation at break was 8.69%. This indicates that during the wet spinning process of this application, the axial traction force causes the cellulose to align axially, while paraffin forms a continuous cross-linked network in the core layer, synergistically improving the overall mechanical properties of the fiber.
[0090] Test Example 8: The cellulose-based composite phase change fibers prepared in Examples 1-3 and the cellulose / photothermal composite fibers prepared in Comparative Example 3 were woven into square fabrics of 2cm × 2.5cm. After weighing, the fabrics were placed in the center of a xenon lamp with an AM·1.5·G filter, and the light intensity was set to 125 mW / cm². 2 The real-time temperature of the fiber was recorded and data was collected using thermocouples connected to a computer, resulting in the fiber's temperature rise curve under illumination and its cooling curve after the light source was turned off. The results are as follows: Figure 9 As shown.
[0091] Depend on Figure 9 It can be seen that the surface temperature of the fabrics in Examples 1-3 and Comparative Example 3 increases with the extension of light exposure time, indicating that the fibers possess photothermal properties. Specifically, Example 1 had a mass of 0.2867 g, a temperature rise enthalpy of 135.06 J / g, a phase transition duration of 75.36 s, and a calculated photothermal conversion efficiency of 82.21%; Example 2 had a mass of 0.463 g, a temperature rise enthalpy of 142.69 J / g, a phase transition duration of 125.67 s, and a calculated photothermal conversion efficiency of 84.11%; and Example 3 had a mass of 0.533 g, a temperature rise enthalpy of 112.28 J / g, a phase transition duration of 117.12 s, and a calculated photothermal conversion efficiency of 81.76%. However, in contrast, Comparative Example 3 did not exhibit a temperature plateau period, indicating that it lacks phase transition properties.
[0092] Test Example 9: The cellulose / phase change material composite thermal management fiber prepared in Example 2 and the cellulose / photothermal composite fiber prepared in Comparative Example 3 were woven into square fabrics with a size of 2cm × 2.5cm. At the same time, commercially available common fabrics (silk, linen, cotton, polyester, wool) were selected and cut into square samples of the same size (2cm × 2.5cm) for comparison of the photothermal and phase change properties of the fabrics.
[0093] The fabric was woven on an 85 °C hot table and then moved to room temperature to cool naturally. The temperature was recorded by an infrared thermal imager throughout the process. Figure 10 Temperature rise and fall curves for different fabrics at 85 °C and 25 °C.
[0094] from Figure 10 As can be seen, during the heating phase, all commercial fabrics (silk, linen, cotton, polyester, and wool) reached their peak saturation temperature within 100 seconds. The fiber textile prepared in Comparative Example 3 reached 65.56 °C in 155 seconds. The fiber textile prepared in Example 2 took 215 seconds to reach 65.66 °C, and a temperature plateau appeared at approximately 55 °C (see the dashed box on the left in the figure), indicating that the sample underwent a solid-liquid transition to achieve phase change heat absorption. During the cooling phase, the temperature of all samples decreased. The fiber textile prepared in Example 2 also showed a temperature plateau at 45 °C (see the dashed box on the right in the figure), indicating that a phase change heat release process from liquid to solid occurred. This effectively mitigated the rapid cooling change of the fiber, and it ultimately took 295 seconds to recover to room temperature. In summary, the cellulose / phase change material composite thermal management fiber of this application possesses excellent phase change heat storage / release capabilities.
Claims
1. A method for preparing cellulose-based composite phase change fibers, the method comprising the following steps: (1) Preparation of cellulose / photothermal material composite spinning solution: The cellulose raw material is completely dissolved in the cellulose solvent, and cellulose auxiliary agent is optionally added. After the cellulose is completely dissolved, the photothermal material is added and the mixture is stirred until it is completely dispersed to obtain the cellulose / photothermal material composite spinning solution. Preparation of nanocellulose / phase change material composite spinning solution: The nanocellulose dispersion in deionized water and the phase change material were thoroughly mixed under stirring to obtain the nanocellulose / phase change material composite spinning solution; (2) Using a spinning solution extrusion device with a coaxial spinning needle having inner and outer layers, the nanocellulose / phase change material composite spinning solution prepared in the previous step is extruded from the inner layer of the coaxial spinning needle, and the cellulose / photothermal material composite spinning solution prepared in the previous step is extruded from the outer layer of the coaxial spinning needle, so that the two spinning solutions are extruded simultaneously. After passing through an air gap of 1-3 cm, they enter the water, and wet composite fibers are obtained through a solvent exchange process; and (3) Place the wet composite fiber prepared in step (2) in water as a coagulation bath and let it stand for 12-24 hours, or change the coagulation bath multiple times, so that the wet composite fiber and the solvent of the coagulation bath can be fully exchanged. Then, dry continuously or dry intermittently in an oven, and finally wind it on a roller to obtain cellulose-based composite phase change fiber.
2. The method according to claim 1, wherein, In step (1), The cellulose raw material is selected from one or more of dissolving wood pulp, refined cotton, and chemical wood pulp, with a degree of polymerization of 400-1500; The cellulose solvent is selected from one or more of superbasic ionic liquids, imidazolium ionic liquids, pyridinium ionic liquids and choline ionic liquids, preferably 1-allyl-3-methylimidazolium chloride or N-propenylpyridinium chloride. The cellulose adjuvant is selected from one or more of dimethyl sulfoxide (DMSO) and dimethylformamide (DMF); The photothermal material is selected from one or more of carbon nanotubes, carbon black, and graphene.
3. The method according to claim 1, wherein, In step (1), The cellulose raw material and cellulose solvent are mixed at a mass ratio of 1:20-30, the mass ratio of cellulose solvent to cellulose auxiliary agent is 5:1-2, and the photothermal material is mixed with the cellulose raw material at a mass ratio of 0.1-1:
1. The conditions for dissolving cellulose raw materials are as follows: stirring at 70-100 °C and 100-800 rpm for 1-6 hours until the cellulose raw materials are completely dissolved in the cellulose solvent.
4. The method according to claim 1, wherein, In step (1), The nanocellulose is selected from one or more of mechanically produced cellulose nanofibers, TEMPO oxidized cellulose nanofibers, and carboxymethylated cellulose nanofibers; and The phase change material is selected from one or more of paraffin, polyethylene glycol, and n-octadecane.
5. The method according to claim 1, wherein, In step (1), The concentration of the cellulose / photothermal material composite spinning solution is 2-8 wt%, and the concentration of the nanocellulose / phase change material composite spinning solution is 4-24 wt%. The mass ratio of the phase change material to the nanocellulose is 9-29:1; The concentration of the nanocellulose dispersion in deionized water is 0.5-1 wt%.
6. The method according to claim 1, wherein, In step (1), The preparation conditions for the nanocellulose / phase change material composite spinning solution are as follows: stirring at 20-100 °C and a speed of 500-8000 rpm for 15 min-1 h to ensure thorough mixing.
7. The method according to claim 1, wherein, In step (2), The coaxial spinning needle with inner and outer double layers is selected from one of 12G, 13G, 14G, 15G, 16G, 17G, 18G, 19G, 20G, 21G, 22G, 23G, 24G, 25G, 26G, 27G, 28G, 30G, and 32G, and the spinning solution extrusion equipment is also equipped with a feed cylinder; and / or The outer layer extrusion temperature is 70-100 °C, and the extrusion speeds of the inner and outer layers are independently 0.02-0.45 ml / min; and / or The air gap is 1-3 cm.
8. A cellulose-based composite phase change fiber prepared by any one of claims 1-7.
9. A thermal management article comprising at least the cellulose-based composite phase change fiber as described in claim 8, preferably, the thermal management article being a fabric.
10. The application of the thermal management product as described in claim 9 in research on human body temperature regulation.