Preparation method of loofah sponge fiber intelligent temperature control material

Abstract

The invention belongs to the technical field of functional material preparation, and particularly relates to a loofah sponge fiber intelligent temperature control material preparation method which comprises the following specific steps: loofah sponge fiber pretreatment: performing chemical pretreatment on natural loofah sponge; performing bleaching, lignin removal and pore structure dredging on the loofah sponge by using a sodium chlorite, hydrogen peroxide or choline chloride-organic acid eutectic solvent (DES) system so as to improve the hydrophilicity of fibers and the loading capacity of microcapsules, and drying the treated loofah sponge for later use; the natural loofah sponge fiber is adopted as a loading framework of the microcapsule, the microcapsule is environmentally friendly and biodegradable, a pore structure is matched with microcapsule embedding, and the material compounding efficiency and the structural stability are effectively improved; the microcapsule prepared in the invention adopts a sodium lignin sulfonate and polyurea composite shell layer, has good thermal stability and packaging performance, and effectively overcomes the leakage problem of the phase change material.

Description

Technical Field

[0001] The invention relates to the technical field of functional material preparation, and in particular to a method for preparing a loofah fiber intelligent temperature control material. Background Art

[0002] With the rapid development of information technology and smart devices, people's demands for environmental comfort, energy efficiency, and energy conservation and environmental protection are increasing. Demand for thermal management materials in areas such as smart wearables, building energy conservation, medical assistance, and vehicle interiors continues to grow. Phase change materials (PCMs), due to their ability to absorb or release large amounts of latent heat during phase changes, are widely used in temperature regulation, thermal buffering, and energy storage, and have become a hot topic in functional materials research.

[0003] Among the many PCMs, aliphatic alkanes, particularly n-octadecane, hold great promise for practical applications due to their high latent heat of phase change, moderate phase transition temperature, and non-toxic and non-corrosive properties. However, due to significant morphological instability during the solid-liquid phase transition, they are prone to liquid phase leakage, leading to reduced energy efficiency, structural damage, and system contamination. Therefore, how to inhibit leakage during heating and improve the service stability of PCMs has become a core issue in this field.

[0004] To address the above-mentioned issues, microencapsulation technology has gradually become a major research topic. Through interfacial polymerization, solvent evaporation, and other technical means, phase change core materials can be encapsulated in polymer shells, significantly improving the encapsulation efficiency and thermal stability of the materials. However, in practical applications, microencapsulated phase change materials still face problems such as difficulty in selecting carrier substrates, low thermal conductivity, and uneven dispersion. In addition, many traditional inorganic or synthetic polymer carriers have problems with poor degradability and insufficient biocompatibility, which restricts their promotion and application in healthy, green, and flexible environments.

[0005] Natural plant fibers, as substrate materials, have gradually attracted widespread attention from researchers due to their wide availability, porous structure, good biocompatibility, and environmental friendliness. Among them, loofah fibers, as a hollow plant material with a three-dimensional mesh structure, possess natural advantages such as large specific surface area, good internal connectivity, and strong load-bearing capacity, making them particularly suitable for constructing carriers for microencapsulated phase change materials. However, research on their integration with microencapsulated phase change materials to achieve stable loading and synergistic performance is still limited, especially lacking systematic loading mechanism design and temperature control performance evaluation.

[0006] In view of the above background, it is urgent to develop a new type of natural porous fiber and high-performance microcapsule phase change material integrated method to improve the practical performance and environmental adaptability of the phase change material and broaden its application range in the field of intelligent temperature control and energy regulation. SUMMARY

[0007] The present application aims to provide a preparation method of luffa fiber intelligent temperature control material to solve the problems in the above background.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a preparation method of luffa fiber intelligent temperature control material, the specific step process of the luffa fiber intelligent temperature control material preparation method is as follows:

[0009] Step one, pretreatment of luffa fiber: chemically pretreat natural luffa, use sodium chlorite, hydrogen peroxide or choline chloride-organic acid deep eutectic solvent (DES) system to bleach, remove lignin and open the pore structure, so as to improve the hydrophilicity of the fiber and the microcapsule loading capacity, and the treated luffa is dried for standby;

[0010] Step two, preparation of phase change microcapsules: use phase change material as core material, sodium lignosulfonate as emulsifier, isophorone diisocyanate (IPDI) and ethylenediamine (EDA) as polyurea shell material, and prepare lignin-based microcapsules with uniform particle size and strong heat sealing property by oil phase, water phase emulsification and interfacial polymerization. Control the emulsion temperature, stirring rate and reaction time to obtain microcapsules with dense shell and excellent stability;

[0011] Step three, preparation of luffa fiber intelligent temperature control material: mix the prepared microcapsule emulsion with the treated luffa fiber, and carry out negative pressure penetration loading reaction under-0.08 to-0.1 MPa for 18 to 36 hours, so that the microcapsules are fully embedded in the internal cavity of the luffa fiber. After loading is completed, the sample is subjected to hot air drying or freeze drying treatment at 40 to 60 DEG C, and the microcapsule-loaded luffa temperature control material is obtained.

[0012] Preferably, in step one, when sodium chlorite is used, the concentration of sodium chlorite solution is 1-10wt%;The temperature used in the reaction is 80℃-100℃, and the mass ratio of luffa to sodium chlorite solution is 1:40-1:10;

[0013] When hydrogen peroxide is used, the concentration of hydrogen peroxide solution is 1-5wt%;The temperature used in the reaction is 100℃-140℃, and the mass ratio of luffa to hydrogen peroxide solution is 1:30-1:10;

[0014] When choline chloride-organic acid deep eutectic solvent is selected, the reaction temperature is 95° C.-110° C., and the mass ratio of loofah sponge to choline chloride-organic acid deep eutectic solvent is 1:20-1:10.

[0015] Preferably, the specific operation of the step 2 is: uniformly mixing the phase change material with ethylenediamine (EDA) and isophorone isocyanate (IPDI) to form an oil phase, dispersing sodium lignin sulfonate in distilled water to form an aqueous phase, and then pouring the oil phase into the aqueous phase, passing through a high-speed homogenizer at an emulsification speed of 6000rpm-15000rpm to obtain an emulsion, and then placing it at 50-90°C, adding ethylenediamine solution dropwise for 2-4h to obtain a phase change microcapsule emulsion.

[0016] Preferably, in step 2, the types of phase change materials are alkanes (n-octadecane), fatty acids and their derivatives (butyl stearate); the mass ratio of phase change material + isophorone isocyanate (IPDI) to lignin sulfonic acid aqueous solution is 1:5-1:20; the core-wall ratio is 4:1-1:1; and the concentration of sodium lignin sulfonate aqueous solution is: 0.4wt%-2.0wt%.

[0017] Preferably, the specific modification operation in step three is: pressurizing the loofah fiber into the phase change microcapsule emulsion for 18-36 hours to obtain the loofah fiber intelligent temperature control material.

[0018] Preferably, in step three, the mass ratio of loofah fiber to phase change microcapsule emulsion is 1:10-1:20.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) This application uses natural loofah fibers as the loading skeleton of microcapsules. It is green, environmentally friendly, biodegradable, and its pore structure is suitable for microcapsule embedding, effectively improving material composite efficiency and structural stability.

[0021] 2) The microcapsules prepared in this application use a composite shell of sodium lignin sulfonate and polyurea, which has good thermal stability and encapsulation performance, effectively overcoming the leakage problem of phase change materials;

[0022] 3) The material in this application has a sensitive overall thermal response, high heat storage and release efficiency, and no significant performance degradation after multiple thermal cycles, making it suitable for multiple repeated use scenarios;

[0023] 4) The process of the present application is simple, the conditions are mild, and there are no toxic by-products in the preparation process, which has good industrial feasibility and environmental adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Flowchart of the steps of this method. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] See also Figure 1 , the present invention provides a technical solution:

[0027] A method for preparing a loofah fiber intelligent temperature control material, the specific steps of the loofah fiber intelligent temperature control material preparation method are as follows:

[0028] Step 1: Pretreatment of loofah fiber: natural loofah is chemically pretreated by using sodium chlorite, hydrogen peroxide or choline chloride-organic acid deep eutectic solvent (DES) system to bleach it, remove lignin and dredge the pore structure to improve the fiber hydrophilicity and microcapsule loading capacity. The treated loofah is dried for later use;

[0029] Step 2: Preparation of Phase Change Microcapsules: Using a phase change material as the core material, sodium lignin sulfonate as the emulsifier, and isophorone isocyanate (IPDI) and ethylenediamine (EDA) as the polyurea shell materials, lignin-based microcapsules with uniform particle size and strong thermal encapsulation properties were prepared through oil-phase and water-phase emulsification and interfacial polymerization. The emulsion temperature, stirring rate, and reaction time were controlled to obtain a microcapsule structure with a dense shell and excellent stability.

[0030] Step 3: Preparation of the loofah fiber intelligent temperature-control material: The prepared microcapsule emulsion is mixed with the treated loofah fibers and subjected to negative pressure osmotic loading for 18-36 hours at -0.08 to -0.1 MPa to fully embed the microcapsules into the loofah fiber cavities. After loading, the sample is hot-air dried or freeze-dried at 40-60°C to obtain the microcapsule-loaded loofah temperature-control material.

[0031] In the step 1, when sodium chlorite is selected, the concentration of the sodium chlorite solution is 1-10 wt %; the reaction temperature is 80° C.-100° C., and the mass ratio of loofah sponge to sodium chlorite solution is 1:40-1:10;

[0032] When hydrogen peroxide is used, the concentration of the hydrogen peroxide solution is 1-5 wt %; the reaction temperature is 100° C.-140° C., and the mass ratio of loofah sponge to hydrogen peroxide solution is 1:30-1:10;

[0033] When choline chloride-organic acid deep eutectic solvent is selected, the reaction temperature is 95° C.-110° C., and the mass ratio of loofah sponge to choline chloride-organic acid deep eutectic solvent is 1:20-1:10.

[0034] The specific operation of step 2 is as follows: uniformly mixing the phase change material with ethylenediamine (EDA) and isophorone isocyanate (IPDI) to form an oil phase, dispersing sodium lignin sulfonate in distilled water to form an aqueous phase, and then pouring the oil phase into the aqueous phase. The mixture is homogenized in a high-speed emulsifier at an emulsification speed of 6000 rpm-15000 rpm to obtain an emulsion, which is then placed at 50-90°C and ethylenediamine solution is added dropwise for 2-4 hours to obtain a phase change microcapsule emulsion.

[0035] In step 2, the types of phase change materials are alkanes (n-octadecane), fatty acids and their derivatives (butyl stearate); the mass ratio of phase change material + isophorone isocyanate (IPDI) to lignin sulfonic acid aqueous solution is 1:5-1:20; the core-to-wall ratio is 4:1-1:1; and the concentration of sodium lignin sulfonate aqueous solution is: 0.4wt%-2.0wt%.

[0036] The specific modification operation in step three is: pressurizing the loofah fiber into the phase change microcapsule emulsion for 18-36 hours to obtain the loofah fiber intelligent temperature control material.

[0037] In the step 3, the mass ratio of loofah fiber to phase change microcapsule emulsion is 1:10-1:20.

[0038] Example 1:

[0039] (1) Preparation of loofah fiber:

[0040] Weigh 15g of loofah fiber into a 200mL beaker, add 2%wt sodium chlorite solution, and heat at 90°C for 4 hours. After the reaction is complete, filter and wash the sample until neutral. Filter, wash, and dry the resulting loofah fiber.

[0041] (2) Preparation of phase change microcapsules:

[0042] Aqueous phase: sodium lignin sulfonate aqueous solution (30 mL, 0.4 wt%); oil phase (2.4 g n-octadecane + 0.6 g IPDI, 3 g in total), the oil phase was poured into the aqueous phase, and then the mixture was emulsified using a homogenizing emulsifier at a speed of 12000 rpm for 3 min to obtain a uniform oil-in-water emulsion with a core-to-wall ratio of 3:1.

[0043] The emulsion was transferred to a three-necked flask and stirred at 70°C on a constant temperature magnetic stirrer at a speed of 450 rpm. Then, ethylenediamine was weighed into 10 ml of distilled water to obtain an ethylenediamine aqueous solution, with the amount of ethylenediamine accounting for 2.9% of the total mass of the ethylenediamine aqueous solution. Then, the ethylenediamine aqueous solution was slowly added to the stirred emulsion, and after complete addition, the emulsification reaction was allowed to proceed at a constant temperature for 5 h to obtain a microcapsule emulsion;

[0044] (3) Preparation of the gourd fiber intelligent temperature control material:

[0045] The microcapsule emulsion prepared above was mixed with the treated gourd fiber, and a vacuum infiltration loading reaction was performed for 24 h to allow the microcapsules to fully embed in the internal cavities of the gourd fiber. After the loading was completed, the sample was subjected to hot air drying or freeze-drying treatment at 40°C to obtain the gourd fiber intelligent temperature control material;

[0046] Example 2:

[0047] (1) Preparation of the gourd fiber:

[0048] 15 g of gourd fiber was weighed into a 200 mL beaker, 2% wt sodium chlorite solution was added, and then heated at 90°C for 4 h. After the reaction was completed, the sample was filtered and washed to neutral. The filtered, washed, and dried gourd fiber was obtained;

[0049] (2) Preparation of the phase change microcapsule:

[0050] Aqueous phase: lignosulfonate sodium aqueous solution (30 mL, 0.6 wt%); oil phase (2.4 g of n-octadecane + 0.6 g of IPDI, a total of 3 g), the oil phase was poured into the aqueous phase, and then a homogeneous emulsion was obtained by using a homogenizing emulsifier to emulsify the mixture at a speed of 12000 rpm for 3 min, with a core-to-wall ratio of 3:1;

[0051] The emulsion was transferred to a three-necked flask and stirred at 70°C on a constant temperature magnetic stirrer at a speed of 450 rpm. Then, ethylenediamine was weighed into 10 ml of distilled water to obtain an ethylenediamine aqueous solution, with the amount of ethylenediamine accounting for 2.9% of the total mass of the ethylenediamine aqueous solution. Then, the ethylenediamine aqueous solution was slowly added to the stirred emulsion, and after complete addition, the emulsification reaction was allowed to proceed at a constant temperature for 5 h to obtain a microcapsule emulsion;

[0052] (3) Preparation of the gourd fiber intelligent temperature control material:

[0053] The microcapsule emulsion prepared above was mixed with the treated gourd fiber, and a vacuum infiltration loading reaction was performed for 24 h to allow the microcapsules to fully embed in the internal cavities of the gourd fiber. After the loading was completed, the sample was subjected to hot air drying or freeze-drying treatment at 40°C to obtain the gourd fiber intelligent temperature control material;

[0054] Example 3:

[0055] (1) Preparation of loofah fiber:

[0056] Weigh 15g of loofah fiber into a 200mL beaker, add 2%wt sodium chlorite solution, and heat at 90°C for 4 hours. After the reaction is complete, filter and wash the sample until neutral. Filter, wash, and dry the resulting loofah fiber.

[0057] (2) Preparation of phase change microcapsules:

[0058] Water phase: sodium lignin sulfonate aqueous solution (30 mL, 0.8 wt%); oil phase (2.4 g n-octadecane + 0.6 g IPDI, 3 g in total), the oil phase was poured into the water phase, and then the mixture was emulsified using a homogenizing emulsifier at 12000 rpm for 3 min to obtain a uniform oil-in-water emulsion with a core-to-wall ratio of 3:1;

[0059] The emulsion was transferred to a three-necked flask and stirred at 450 rpm on a thermostatic magnetic stirrer at 70°C. Next, ethylenediamine was weighed and dissolved in 10 ml of distilled water, so that the ethylenediamine solution accounted for 2.9% of the total mass of the ethylenediamine aqueous solution. The ethylenediamine aqueous solution was then slowly added to the stirred emulsion. After complete addition, the emulsification reaction was allowed to proceed at a stable temperature for 5 hours to obtain a microcapsule emulsion.

[0060] (3) Preparation of loofah fiber intelligent temperature control material:

[0061] The prepared microcapsule emulsion was mixed with the treated loofah fibers and subjected to negative pressure osmotic loading for 24 hours to allow the microcapsules to fully embed into the loofah fiber cavities. After loading, the sample was dried with hot air at 40°C or freeze-dried to obtain the loofah fiber intelligent temperature control material.

[0062] Example 4:

[0063] (1) Preparation of loofah fiber:

[0064] Weigh 15g of loofah fiber into a 200mL beaker, add 2%wt sodium chlorite solution, and heat at 90°C for 4 hours. After the reaction is complete, filter and wash the sample until neutral. Filter, wash, and dry the resulting loofah fiber.

[0065] (2) Preparation of phase change microcapsules:

[0066] Water phase: sodium lignosulfonate aqueous solution (30 mL, 1.0 wt%); oil phase (2.4 g n-octadecane + 0.6 g IPDI, total 3 g), pour the oil phase into the water phase, then use a homogenizing emulsifier to emulsify the mixture at a speed of 12000 rpm for 3 min to obtain a uniform oil-in-water emulsion, core wall ratio 3:1.

[0067] The emulsion was transferred to a three-necked flask and stirred on a constant temperature magnetic stirrer at 70°C at a speed of 450 rpm. Then, according to the total mass of ethylenediamine aqueous solution, 2.9% of ethylenediamine was weighed and dissolved in 10 ml of distilled water to obtain an ethylenediamine aqueous solution. Then, the ethylenediamine aqueous solution was slowly added to the stirred emulsion, and after complete addition, the emulsification reaction was allowed to proceed at a stable temperature for 5 h to obtain a microcapsule emulsion, core wall ratio 3:1; (3) Preparation of luffa fiber intelligent temperature control material:

[0068] The above prepared microcapsule emulsion was mixed with the treated luffa fiber, and a microcapsule was fully embedded in the internal cavity of the luffa fiber by performing a vacuum infiltration loading reaction for 24 hours. After loading was completed, the sample was subjected to hot air drying or freeze drying treatment at 40°C to obtain a luffa fiber intelligent temperature control material;

[0069] Example 5:

[0070] (1) Preparation of luffa fiber:

[0071] 15 g of luffa fiber was weighed and placed in a 200 mL beaker, 2% wt sodium chlorite solution was added, and then heated at 90°C for 4 h. After the reaction was completed, the sample was filtered and washed to neutral. The filtered, washed and dried luffa fiber was obtained;

[0072] (2) Preparation of phase change microcapsules:

[0073] Water phase: sodium lignosulfonate aqueous solution (30 mL, 1.2 wt%); oil phase (2.4 g n-octadecane + 0.6 g IPDI, total 3 g), pour the oil phase into the water phase, then use a homogenizing emulsifier to emulsify the mixture at a speed of 12000 rpm for 3 min to obtain a uniform oil-in-water emulsion, core wall ratio 3:1;

[0074] The emulsion was transferred to a three-necked flask and stirred on a constant temperature magnetic stirrer at 70°C at a speed of 450 rpm. Then, according to the total mass of ethylenediamine aqueous solution, 2.9% of ethylenediamine was weighed and dissolved in 10 ml of distilled water to obtain an ethylenediamine aqueous solution. Then, the ethylenediamine aqueous solution was slowly added to the stirred emulsion, and after complete addition, the emulsification reaction was allowed to proceed at a stable temperature for 5 h to obtain a microcapsule emulsion;

[0075] (3) Preparation of luffa fiber intelligent temperature control material:

[0076] The prepared microcapsule emulsion was mixed with the treated loofah fibers and subjected to negative pressure osmotic loading for 24 hours to allow the microcapsules to fully embed into the loofah fiber cavities. After loading, the sample was dried with hot air at 40°C or freeze-dried to obtain the loofah fiber intelligent temperature control material.

[0077] Example 6:

[0078] (1) Preparation of loofah fiber:

[0079] Weigh 15g of loofah fiber into a 200mL beaker, add 2%wt sodium chlorite solution, and heat at 90°C for 4 hours. After the reaction is complete, filter and wash the sample until neutral. Filter, wash, and dry the resulting loofah fiber.

[0080] (2) Preparation of phase change microcapsules:

[0081] Water phase: sodium lignin sulfonate aqueous solution (30 mL, 0.8 wt%); oil phase (2.4 g n-octadecane + 0.6 g IPDI, 3 g in total), the oil phase was poured into the water phase, and then the mixture was emulsified using a homogenizing emulsifier at 12000 rpm for 3 min to obtain a uniform oil-in-water emulsion with a core-to-wall ratio of 4:1;

[0082] The emulsion was transferred to a three-necked flask and stirred at 450 rpm on a thermostatic magnetic stirrer at 70°C. Next, ethylenediamine was weighed and dissolved in 10 ml of distilled water, so that the ethylenediamine solution accounted for 2.9% of the total mass of the ethylenediamine aqueous solution. The ethylenediamine aqueous solution was then slowly added to the stirred emulsion. After complete addition, the emulsification reaction was allowed to proceed at a stable temperature for 5 hours to obtain a microcapsule emulsion.

[0083] (3) Preparation of loofah fiber intelligent temperature control material:

[0084] The prepared microcapsule emulsion was mixed with the treated loofah fibers and subjected to negative pressure osmotic loading for 24 hours to allow the microcapsules to fully embed into the loofah fiber cavities. After loading, the sample was dried with hot air at 40°C or freeze-dried to obtain the loofah fiber intelligent temperature control material.

[0085] Example 7:

[0086] (1) Preparation of loofah fiber:

[0087] Weigh 15g of loofah fiber into a 200mL beaker, add 2%wt sodium chlorite solution, and heat at 90°C for 4 hours. After the reaction is complete, filter and wash the sample until neutral. Filter, wash, and dry the resulting loofah fiber.

[0088] (2) Preparation of phase change microcapsules:

[0089] Water phase: sodium lignin sulfonate aqueous solution (30 mL, 0.8 wt%); oil phase (2.4 g n-octadecane + 0.6 g IPDI, 3 g in total), the oil phase was poured into the water phase, and then the mixture was emulsified using a homogenizing emulsifier at 12000 rpm for 3 min to obtain a uniform oil-in-water emulsion with a core-to-wall ratio of 2:1;

[0090] The emulsion was transferred to a three-necked flask and stirred at 450 rpm on a thermostatic magnetic stirrer at 70°C. Next, ethylenediamine was weighed and dissolved in 10 ml of distilled water, so that the ethylenediamine solution accounted for 2.9% of the total mass of the ethylenediamine aqueous solution. The ethylenediamine aqueous solution was then slowly added to the stirred emulsion. After complete addition, the emulsification reaction was allowed to proceed at a stable temperature for 5 hours to obtain a microcapsule emulsion.

[0091] (3) Preparation of loofah fiber intelligent temperature control material:

[0092] The prepared microcapsule emulsion was mixed with the treated loofah fibers and subjected to negative pressure osmotic loading for 24 hours to allow the microcapsules to fully embed into the loofah fiber cavities. After loading, the sample was dried with hot air at 40°C or freeze-dried to obtain the loofah fiber intelligent temperature control material.

[0093] Example 8:

[0094] (1) Preparation of loofah fiber:

[0095] Weigh 15g of loofah fiber into a 200mL beaker, add 2%wt sodium chlorite solution, and heat at 90°C for 4 hours. After the reaction is complete, filter and wash the sample until neutral. Filter, wash, and dry the resulting loofah fiber.

[0096] (2) Preparation of phase change microcapsules:

[0097] Water phase: sodium lignin sulfonate aqueous solution (30 mL, 0.8 wt%); oil phase (2.4 g n-octadecane + 0.6 g IPDI, 3 g in total), the oil phase was poured into the water phase, and then the mixture was emulsified using a homogenizing emulsifier at 12000 rpm for 3 min to obtain a uniform oil-in-water emulsion with a core-to-wall ratio of 1:1;

[0098] The emulsion was transferred to a three-necked flask and stirred at 450 rpm on a thermostatic magnetic stirrer at 70°C. Next, ethylenediamine was weighed and dissolved in 10 ml of distilled water, so that the ethylenediamine solution accounted for 2.9% of the total mass of the ethylenediamine aqueous solution. The ethylenediamine aqueous solution was then slowly added to the stirred emulsion. After complete addition, the emulsification reaction was allowed to proceed at a stable temperature for 5 hours to obtain a microcapsule emulsion.

[0099] (3) Preparation of loofah fiber intelligent temperature control material:

[0100] The prepared microcapsule emulsion was mixed with the treated loofah fibers and subjected to negative pressure osmotic loading for 24 hours to fully embed the microcapsules into the loofah fiber cavities. After loading, the sample was dried with hot air at 40°C or freeze-dried to obtain the loofah fiber intelligent temperature-control material.

[0101] Performance testing:

[0102] The products prepared in Examples 1-8 were subjected to performance tests, including morphology observation, Fourier transform infrared, X-ray diffraction, thermogravimetric testing, XPS elemental analysis, differential scanning calorimeter analysis, and leak test analysis.

[0103] Table 1 DSC data of phase change microcapsules

[0104]

[0105] Table 2 Anti-leakage performance test of phase change microcapsules

[0106]

[0107]

[0108] Microencapsulation of n-octadecane with lignin / polyurea via interfacial polymerization has been considered a feasible approach to synthesize phase-change microcapsules with a lignin / polyurea double-layer shell.

[0109] The core-to-wall ratio has a great influence on the performance of microcapsules. If the core-to-wall ratio is too small, it will lead to excessive wall material. The excess wall material will homogeneously nucleate to form pure polymers adhering to the surface of the microcapsules, which will not only affect the morphology of the microcapsules, but also reduce the energy storage performance of the phase change microcapsules. If the core-to-wall ratio is too large, it will lead to insufficient wall material, so that the emulsion droplets cannot be completely coated or the shell wall of the microcapsule is too thin, causing the shell wall to rupture and affecting the sealing performance of the microcapsules.

[0110] At low concentrations (0.4wt%, 0.6wt%), sodium lignin sulfonate's ability to encapsulate the core material is insufficient, potentially leading to cracked or collapsed microcapsules. This is because sodium lignin sulfonate plays a key role in building the outer shell during microcapsule preparation, and its dosage directly affects the physical properties of the microcapsule surface. When the amount of sodium lignin sulfonate used is low, the surface tension of the microcapsules decreases. Surface tension is a key factor in maintaining the structural stability of microcapsules. Lower surface tension weakens the microcapsules' resistance to external forces, such as stirring and shearing forces during the preparation process, making them more susceptible to breakage. Low sodium lignin sulfonate dosages can reduce the surface tension of microcapsules, making them more susceptible to breakage. At high concentrations (1.2wt%), excessive cross-linking can lead to microcapsules of varying sizes and high levels of impurities. This is because the shear forces during the microcapsule molding process increase, leading to uneven microcapsule shapes and a tendency to cause variability. Furthermore, increasing lignin content increases the surface tension of the microcapsules, weakening the mutual attraction between microcapsules and causing them to agglomerate and accumulate impurities. Therefore, when the concentration of sodium lignin sulfonate is 0.8wt% and the core-to-wall ratio is 3:1, the microcapsule phase change latent heat is the largest and the anti-leakage performance is the best.

[0111] Table 3 DSC data of loofah intelligent temperature control fiber

[0112]

[0113] Table 4 Real-time temperature control performance test of loofah intelligent temperature control fiber

[0114]

[0115] Because when the sodium lignin sulfonate concentration is 0.8wt% and the core-to-wall ratio is 3:1, the microcapsule phase change latent heat is the highest and the anti-leakage performance is the best. Therefore, under the same loading rate, the loofah fiber intelligent temperature control material prepared with these phase change microcapsules has the best intelligent temperature control effect.

[0116] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the appended claims rather than the above description. Therefore, it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure signs in the claims should not be regarded as limiting the claims involved.

[0117] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a loofah fiber intelligent temperature control material, characterized in that: The specific steps of the preparation method of the loofah fiber intelligent temperature control material are as follows: Step 1: Pretreatment of loofah fiber: natural loofah is chemically pretreated by using sodium chlorite, hydrogen peroxide or choline chloride-organic acid deep eutectic solvent (DES) system to bleach it, remove lignin and dredge the pore structure to improve the fiber hydrophilicity and microcapsule loading capacity. The treated loofah is dried for later use; Step 2: Preparation of Phase Change Microcapsules: Using a phase change material as the core material, sodium lignin sulfonate as the emulsifier, and isophorone isocyanate (IPDI) and ethylenediamine (EDA) as the polyurea shell materials, lignin-based microcapsules with uniform particle size and strong thermal encapsulation properties were prepared through oil-phase and water-phase emulsification and interfacial polymerization. The emulsion temperature, stirring rate, and reaction time were controlled to obtain a microcapsule structure with a dense shell and excellent stability. Step 3: Preparation of the loofah fiber intelligent temperature-control material: The prepared microcapsule emulsion is mixed with the treated loofah fibers and subjected to negative pressure osmotic loading for 18-36 hours at -0.08 to -0.1 MPa to fully embed the microcapsules into the loofah fiber cavities. After loading, the sample is hot-air dried or freeze-dried at 40-60°C to obtain the microcapsule-loaded loofah temperature-control material.

2. The method for preparing a loofah fiber intelligent temperature control material according to claim 1, wherein: In the step 1, when sodium chlorite is selected, the concentration of the sodium chlorite solution is 1-10 wt %; the reaction temperature is 80° C.-100° C., and the mass ratio of loofah sponge to sodium chlorite solution is 1:40-1:10; When hydrogen peroxide is used, the concentration of the hydrogen peroxide solution is 1-5 wt %; the reaction temperature is 100° C.-140° C., and the mass ratio of loofah sponge to hydrogen peroxide solution is 1:30-1:10; When choline chloride-organic acid deep eutectic solvent is selected, the reaction temperature is 95° C.-110° C., and the mass ratio of loofah sponge to choline chloride-organic acid deep eutectic solvent is 1:20-1:

10.

3. The method for preparing a loofah fiber intelligent temperature control material according to claim 1, wherein: The specific operation of step 2 is as follows: uniformly mixing the phase change material with ethylenediamine (EDA) and isophorone isocyanate (IPDI) to form an oil phase, dispersing sodium lignin sulfonate in distilled water to form an aqueous phase, and then pouring the oil phase into the aqueous phase. The mixture is homogenized in a high-speed emulsifier at an emulsification speed of 6000 rpm-15000 rpm to obtain an emulsion, which is then placed at 50-90°C and ethylenediamine solution is added dropwise for 2-4 hours to obtain a phase change microcapsule emulsion.

4. The method for preparing a loofah fiber intelligent temperature control material according to claim 1, wherein: In step 2, the types of phase change materials are alkanes (n-octadecane), fatty acids and their derivatives (butyl stearate); the mass ratio of phase change material + isophorone isocyanate (IPDI) to lignin sulfonic acid aqueous solution is 1:5-1:20; the core-to-wall ratio is 4:1-1:1; and the concentration of sodium lignin sulfonate aqueous solution is: 0.4wt%-2.0wt%.

5. The method for preparing a loofah fiber intelligent temperature control material according to claim 1, wherein: The specific modification operation in step three is: pressurizing the loofah fiber into the phase change microcapsule emulsion for 18-36 hours to obtain the loofah fiber intelligent temperature control material.

6. The method for preparing a loofah fiber intelligent temperature control material according to claim 1, wherein: In the step 3, the mass ratio of loofah fiber to phase change microcapsule emulsion is 1:10-1:20.

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