Preparation method of light-permeable phase-change bamboo wood
By using an acidic sodium chlorite system and a vacuum impregnation method, phase change materials were successfully combined with bamboo, solving the problem of efficiently loading phase change materials onto bamboo while maintaining the integrity of its porous structure. This resulted in the preparation of bamboo with high phase change enthalpy and light transmittance, suitable for building energy-saving materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-12
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of bamboo processing technology, and more specifically, to a method for preparing translucent phase-change bamboo. Background Technology
[0002] With the global energy structure transformation and increasing demand for building energy conservation, the development of green building materials with photothermal regulation capabilities is of great significance. Phase change materials can reversibly absorb and release a large amount of latent heat through a phase change process, significantly improving the temperature regulation capability and energy efficiency of building envelopes. Combining them with traditional building materials holds promise for the development of a new generation of intelligent energy-saving materials.
[0003] Bamboo, as a fast-growing and renewable biomass resource, is highly similar to wood in structure and chemical composition, making it an ideal substrate for preparing functional composite materials. In recent years, the development of transparent wood based on delignification technology has demonstrated a feasible path to impart translucency to biomass substrates. However, the increasing scarcity of wood resources has prompted research to shift towards bamboo. The longitudinal and transverse dissolution differences of lignin and hemicellulose in bamboo are significant. The sodium hydroxide and sodium sulfite solution method for preparing translucent wood is time-consuming; therefore, this invention uses the sodium chlorite solution method.
[0004] Meanwhile, simply using translucent materials cannot meet the needs of buildings for dynamic thermal management. How to efficiently and stably integrate phase change energy storage into a translucent bamboo matrix to form a composite material with both light transmission and thermal regulation characteristics has become a current research challenge and focus. In existing technologies, direct impregnation often fails to maintain the integrity of the bamboo's porous structure while achieving high load-bearing capacity and leak-proof properties for phase change materials.
[0005] Therefore, developing an efficient and structurally friendly method for removing lignin from bamboo, and on this basis constructing a structurally stable, light-transmitting phase-change bamboo material with both photothermal and thermal properties, is of urgent practical significance for expanding the high-value application of bamboo and promoting the development of building energy-saving technologies. Summary of the Invention
[0006] To achieve the above objectives, the present invention provides a method for preparing translucent phase change bamboo, which involves selectively removing lignin from bamboo using an acidic sodium chlorite system, followed by vacuum impregnation to prepare phase change bamboo.
[0007] In this invention, acidic sodium chlorite can maintain the integrity of bamboo fiber structure while selectively removing lignin. The method uses inexpensive and readily available raw materials and is simple to operate.
[0008] The transparent bamboo material prepared by this invention has light transmittance and phase change energy storage characteristics. Its melting enthalpy change at room temperature is greater than 80 J / g, and its phase change enthalpy is 65% of that of polyethylene glycol 800. It is also light-transmitting.
[0009] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing translucent phase-change bamboo includes the following steps: Step 1: Pre-treat the bamboo material; Step 2: Immerse the pretreated bamboo in sodium hydroxide solution and slowly stir at 80℃ for 8-10 hours for alkali treatment. After the reaction is complete, wash off the residual reagent with hot water. Step 3: Immerse the alkali-treated bamboo in a delignification solution and react at 80℃~90℃ for 3h~8h to remove lignin. After the reaction, wash the residual reagent with hot water and immerse the lignin-free bamboo in anhydrous ethanol for later use. Step 4: Immerse the lignin-free bamboo in the mixed solution and perform vacuum impregnation treatment. Then, remove the bamboo strips and heat them to solidify, thereby obtaining translucent phase change bamboo.
[0010] Furthermore, the pretreatment method in step 1 is to slice the bamboo into appropriate sizes and polish it smooth.
[0011] Furthermore, the sodium hydroxide solution in step 2 has a mass fraction of 1% to 2%, and the mass of the sodium hydroxide solution is 20 to 40 times the mass of the pretreated bamboo material.
[0012] Furthermore, the delignification solution in step 3 is a mixed solution of sodium chlorite and acetic acid. The preparation method is as follows: first, add sodium chlorite to water to prepare a sodium chlorite solution with a mass fraction of 3-5%, and then add acetic acid to adjust the pH value of the solution to 4.6.
[0013] Furthermore, in step 3, the mass of the delignification solution is 20 to 30 times the mass of the bamboo material after alkali treatment.
[0014] Furthermore, the preparation method of the mixed solution in step 4 is as follows: epoxy resin and polyethylene glycol are mixed at a mass ratio of 8~6:2~4, heated to 60℃ and stirred for 1 hour, then the curing agent is added and stirred for 20~30 minutes to obtain the mixed solution.
[0015] Furthermore, the epoxy resin is E51; the curing agent is obtained by mixing polyetheramine D-230 and N,N-dimethylacrylamide DMAPA in a mass ratio of 9:1; wherein the mass ratio of the curing agent to the epoxy resin is 3~4:7~6.
[0016] Furthermore, during the vacuum impregnation process in step 4, the pressure is released to atmospheric pressure for 1 minute after every 10 minutes of impregnation, and this process is repeated 3 to 5 times.
[0017] Furthermore, in step 4, the heating and curing process involves maintaining the temperature at 60~70℃ for 24 hours.
[0018] The light-transmitting phase change bamboo material prepared by this invention has light transmittance and high enthalpy value, with a phase change enthalpy greater than 80 J / g, and can be used in energy-saving building components and smart home materials.
[0019] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The delignification process used in this invention significantly improves the permeability of chemical reagents in dense bamboo through optimized pretreatment steps. While maintaining the integrity of the porous skeleton structure of bamboo, it effectively shortens the overall processing time and provides a structural basis for subsequent functionalization.
[0020] 2. This invention innovatively combines phase change material (polyethylene glycol PEG800) with a bamboo matrix, successfully introducing active thermal management functionality while imparting good light transmittance to the material. The prepared light-transmitting phase change bamboo exhibits high phase change enthalpy and cycle stability, achieving synergy between light transmission and thermal energy storage and release, significantly enhancing its application potential in the field of building energy conservation.
[0021] 3. The preparation method of this invention has simple process steps. The acidic sodium chlorite delignification system used combines structural alkali treatment and vacuum impregnation, which achieves efficient delignification and high loading of phase change materials while taking into account the operability of the process and the final performance of the material.
[0022] 4. The transparent bamboo material prepared by this invention has light transmittance and high enthalpy value, with a phase change enthalpy greater than 80 J / g. It can be used as a light-transmitting window with heat storage function, an interior partition, a decorative panel, and a light and heat management furniture component. Attached Figure Description
[0023] Figure 1 Images showing the appearance of raw bamboo, transparent bamboo, and phase-change translucent bamboo; Figure 2 DSC for PEG800, PCW and PCW-bamboo; Figure 3 The images show the appearance of PEG800, PCW, and PCW-bamboo at room temperature and 60℃. Detailed Implementation
[0024] To enable those skilled in the art to more clearly understand the present invention, the invention will be further described in detail below with reference to embodiments and accompanying drawings. However, it should be understood that the following embodiments are merely preferred embodiments of the invention, and the scope of protection of the invention should be determined by the scope defined in the claims. In the description of the invention, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially. In some embodiments, raw materials, methods, and means well known to those skilled in the art are not described in detail in order to highlight the spirit of the invention.
[0025] Example 1 A method for preparing translucent phase-change bamboo includes the following steps: Step 1: Pre-treat the bamboo: Cut the bamboo into strips of 30mm (length) × 7mm (width) × 1mm (thickness), polish them smooth, and then wash them with deionized water; Step 2: Prepare a 1% sodium hydroxide solution and immerse the pretreated bamboo in the sodium hydroxide solution. The mass of the sodium hydroxide solution is 20 times the mass of the pretreated bamboo. Stir slowly at 80℃ for 8 hours to carry out alkaline treatment. After the reaction is completed, wash off the residual reagent with boiling water. Step 3: First, add sodium chlorite to water to prepare a 5% sodium chlorite solution by mass. Then, add acetic acid to adjust the pH of the solution to 4.6 to obtain a delignification solution. The alkali-treated bamboo was immersed in a delignification solution, the mass of which was 30 times the mass of the alkali-treated bamboo. The reaction was carried out at 90°C for 3 hours to remove lignin. After the reaction, the residual reagent was washed with boiling water. The bamboo after lignin removal was then immersed in anhydrous ethanol for later use. Step 4: Mix epoxy resin (epoxy resin is E51) and polyethylene glycol at a mass ratio of 8:2, heat to 60℃ and stir for 1 hour, then add curing agent, which is obtained by mixing polyetheramine D-230 and N,N-dimethylacrylamide DMAPA at a mass ratio of 9:1. The mass ratio of curing agent to epoxy resin is 3:7. Stir for 20 minutes to obtain a mixed solution. Bamboo with lignin removed is immersed in a mixed solution and subjected to vacuum impregnation. The entire bamboo is impregnated under vacuum for 10 minutes and then released to atmospheric pressure for 1 minute. This process is repeated 3 times. The bamboo pieces are then removed and heated to 60°C for 24 hours to cure the phase change translucent bamboo, i.e., PCW-bamboo.
[0026] Example 2 A method for preparing translucent phase-change bamboo includes the following steps: Step 1: Pre-treat the bamboo: Cut the bamboo into strips of 30mm (length) × 7mm (width) × 1mm (thickness), polish them smooth, and then wash them with deionized water; Step 2: Prepare a 1.5% sodium hydroxide solution and immerse the pretreated bamboo in the sodium hydroxide solution. The mass of the sodium hydroxide solution should be 40 times the mass of the pretreated bamboo. Stir slowly at 80℃ for 10 hours to perform alkali treatment. After the reaction is complete, wash off the residual reagent with boiling water. Step 3: First, add sodium chlorite to water to prepare a 4% sodium chlorite solution. Then, add acetic acid to adjust the pH of the solution to 4.6 to obtain a delignification solution. The alkali-treated bamboo was immersed in a delignification solution, the mass of which was 20 times the mass of the alkali-treated bamboo. The reaction was carried out at 80°C for 8 hours to remove lignin. After the reaction was completed, the residual reagent was washed with boiling water. The bamboo after lignin removal was then immersed in anhydrous ethanol for later use. Step 4: Mix epoxy resin (epoxy resin is E51) and polyethylene glycol at a mass ratio of 7:3, heat to 60℃ and stir for 1 hour, then add curing agent. The curing agent is obtained by mixing polyetheramine D-230 and N,N-dimethylacrylamide DMAPA at a mass ratio of 9:1. The mass ratio of curing agent to epoxy resin is 4:6. Stir for 20 minutes to obtain a mixed solution. Bamboo with lignin removed is immersed in a mixed solution and subjected to vacuum impregnation. The entire bamboo is impregnated under vacuum for 10 minutes and then released to atmospheric pressure for 1 minute. This process is repeated 4 times. The bamboo pieces are then removed and heated to 70°C for 24 hours to cure the bamboo, thus obtaining phase change translucent bamboo.
[0027] Example 3 A method for preparing translucent phase-change bamboo includes the following steps: Step 1: Pre-treat the bamboo: Cut the bamboo into strips of 30mm (length) × 7mm (width) × 1mm (thickness), polish them smooth, and then wash them with deionized water; Step 2: Prepare a 1.5% sodium hydroxide solution and immerse the pretreated bamboo in the sodium hydroxide solution. The mass of the sodium hydroxide solution is 30 times the mass of the pretreated bamboo. Stir slowly at 80℃ for 9 hours to carry out alkali treatment. After the reaction is completed, wash off the residual reagent with boiling water. Step 3: First, add sodium chlorite to water to prepare a 5% sodium chlorite solution by mass. Then, add acetic acid to adjust the pH of the solution to 4.6 to obtain a delignification solution. The alkali-treated bamboo was immersed in a delignification solution, the mass of which was 30 times the mass of the alkali-treated bamboo. The reaction was carried out at 90°C for 5 hours to remove lignin. After the reaction, the residual reagent was washed with boiling water. The bamboo after lignin removal was then immersed in anhydrous ethanol for later use. Step 4: Mix epoxy resin (epoxy resin is E51) and polyethylene glycol at a mass ratio of 6:4, heat to 60℃ and stir for 1 hour, then add curing agent. The curing agent is obtained by mixing polyetheramine D-230 and N,N-dimethylacrylamide DMAPA at a mass ratio of 9:1. The mass ratio of curing agent to epoxy resin is 3:7. Stir for 25 minutes to obtain a mixed solution. The lignin-free bamboo was impregnated in a mixed solution and subjected to vacuum impregnation. The entire bamboo was impregnated under vacuum for 10 minutes and then released to atmospheric pressure for 1 minute. This process was repeated 5 times. The bamboo pieces were then removed and heated to 70°C for 24 hours to obtain phase change transparent bamboo.
[0028] Example 4 A method for preparing translucent phase-change bamboo includes the following steps: Step 1: Pre-treat the bamboo: Cut the bamboo into strips of 30mm (length) × 7mm (width) × 1mm (thickness), polish them smooth, and then wash them with deionized water; Step 2: Prepare a 2% sodium hydroxide solution and immerse the pretreated bamboo in the sodium hydroxide solution. The mass of the sodium hydroxide solution is 40 times the mass of the pretreated bamboo. Stir slowly at 80℃ for 8 hours to carry out alkaline treatment. After the reaction is completed, wash off the residual reagent with boiling water. Step 3: First, add sodium chlorite to water to prepare a 3% sodium chlorite solution. Then, add acetic acid to adjust the pH of the solution to 4.6 to obtain a delignification solution. The alkali-treated bamboo was immersed in a delignification solution, the mass of which was 25 times the mass of the alkali-treated bamboo. The reaction was carried out at 85°C for 6 hours to remove lignin. After the reaction, the residual reagent was washed with boiling water. The bamboo after lignin removal was then immersed in anhydrous ethanol for later use. Step 4: Mix epoxy resin (epoxy resin is E51) and polyethylene glycol at a mass ratio of 8:2, heat to 60℃ and stir for 1 hour, then add curing agent. The curing agent is obtained by mixing polyetheramine D-230 and N,N-dimethylacrylamide DMAPA at a mass ratio of 9:1. The mass ratio of curing agent to epoxy resin is 4:6. Stir for 30 minutes to obtain a mixed solution. Bamboo with lignin removed is immersed in a mixed solution and subjected to vacuum impregnation. The entire bamboo is impregnated under vacuum for 10 minutes and then released to atmospheric pressure for 1 minute. This process is repeated 5 times. The bamboo pieces are then removed and heated to 65°C for 24 hours to cure the bamboo and obtain phase change translucent bamboo.
[0029] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that polyethylene glycol is not added when preparing the mixed solution in step 4. The other steps are the same, and transparent bamboo strips are obtained.
[0030] Comparative Example 2 Epoxy resin (E51) and polyethylene glycol were mixed at a mass ratio of 8:2, heated to 60°C and stirred for 1 hour. Then, a curing agent was added, which was obtained by mixing polyetheramine D-230 and N,N-dimethylacrylamide DMAPA at a mass ratio of 9:1. The mass ratio of the curing agent to the epoxy resin was 3:7. The mixture was stirred for 20 minutes to obtain a mixed solution. The mixed solution was then heated and cured at 70°C for 24 hours to obtain the phase change material PCW.
[0031] Performance testing 1. Appearance characteristics Figure 1 The images show the appearance of raw bamboo, transparent bamboo (Comparative Example 1), and phase-change translucent bamboo (Example 1). Figure 1 It can be seen that the microstructure of the transparent bamboo material in Comparative Example 1 and the phase change light-transmitting bamboo material in Example 1 has undergone slight deformation compared with the original bamboo material, indicating that the lignin of the bamboo strips has been removed, and the phase change light-transmitting bamboo material in Example 1 still has the effect of light transmission.
[0032] 2. Thermal performance analysis Take 8 mg of sample, heat it to 60 °C at a heating rate of 5 °C / min under nitrogen protection, and then cool it down to 0 °C. The test is carried out in the temperature range of 0~60 °C.
[0033] Test data such as Figure 2 As shown in Table 1, PEG800 is pure polyethylene glycol 800, PCW is the product of Comparative Example 2, and PCW-bamboo is the product of Example 1. Table 1 shows that PEG800 has a latent heat of melting of 126 J / g and a phase transition peak temperature of 33℃; its latent heat of crystallization is 114 J / g and its phase transition peak temperature is 18℃. When the temperature is higher than the melting temperature, PEG800 undergoes a solid-liquid phase transition, absorbing and storing a large amount of latent heat. When the temperature drops to the crystallization temperature, PEG800 solidifies and crystallizes, releasing the stored latent heat back into the environment. Comparing the data of the three, it can be seen that the enthalpy of melting and crystallization of PCW and PCW-bamboo decrease less than that of PEG800, and no leakage occurs.
[0034] Table 1
[0035] 3. Durability Performance Analysis Under nitrogen protection, with a heating rate of 5℃ / min and a heating / cooling range of 0~60℃, after 100 cycles of thermal cycling, compared with the initial state, the phase change temperature and phase change enthalpy of the phase change translucent bamboo material of Example 1 did not change much. After cycling, the peak phase change temperature increased by 2℃ and 1.1℃, respectively, while the latent heat of crystallization and latent heat of melting decreased by 5% and 0.46%, respectively. The DSC curves of the phase change translucent bamboo material of Example 1 after cycling basically overlapped with those of the sample before cycling. This is because most of the polyethylene glycol is combined through the three-dimensional network structure of epoxy resin and the hydrogen bond interaction between bamboo and PCW, effectively solving the leakage problem in the phase change process, thereby ensuring the durability of heat storage and release performance.
[0036] Figure 3 The images show the appearance of PEG800, PCW, and PCW-bamboo at room temperature and 60℃. At room temperature, PEG800, PCW, and PCW-bamboo are all solid. When the temperature rises above the phase transition temperature, PEG800 melts into a liquid state, while PCW transforms into a gel state without mechanical support. In contrast, PCW-bamboo does not show any significant changes in appearance. This phenomenon is attributed to the three-dimensional porous support structure formed by the bamboo skeleton in PCW-bamboo. This structure provides stable mechanical support for PCW during the phase transition process, thereby maintaining the integrity of the material's macroscopic shape.
[0037] The phase change translucent bamboo material prepared by this invention retains the original properties of bamboo while possessing light transmittance and high enthalpy value, and can be used as a translucent window with heat storage function, interior partition, decorative panel and light and heat management furniture component.
[0038] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A method for preparing translucent phase-change bamboo, characterized in that, Includes the following steps: Step 1: Pre-treat the bamboo material; Step 2: Immerse the pretreated bamboo in sodium hydroxide solution and stir at 80℃ for 8-10 hours for alkali treatment. After the reaction is complete, wash off any residual reagents. Step 3: Immerse the alkali-treated bamboo in a delignification solution and react at 80℃~90℃ for 3h~8h to remove lignin. After the reaction, wash off the residual reagent and immerse the lignin-free bamboo in anhydrous ethanol for later use. Step 4: Immerse the lignin-free bamboo in the mixed solution and perform vacuum impregnation treatment. Then, remove the bamboo strips and heat them to solidify, thereby obtaining translucent phase change bamboo.
2. The method for preparing translucent phase-change bamboo according to claim 1, characterized in that, In step 1, the bamboo is pre-treated by slicing it and then polishing it smooth.
3. The method for preparing translucent phase-change bamboo according to claim 1, characterized in that, In step 2, the sodium hydroxide solution has a mass fraction of 1% to 2%, and the mass of the sodium hydroxide solution is 20 to 40 times that of the pretreated bamboo.
4. The method for preparing translucent phase-change bamboo according to claim 1, characterized in that, The preparation method of delignification solution in step 3 is as follows: first, prepare a sodium chlorite solution with a mass fraction of 3-5%, and then add acetic acid to adjust the pH value of the solution to 4.
6.
5. The method for preparing translucent phase-change bamboo according to claim 1, characterized in that, In step 3, the mass of the delignification solution should be 20 to 30 times that of the alkali-treated bamboo.
6. The method for preparing translucent phase-change bamboo according to claim 1, characterized in that, The preparation method of the mixed solution in step 4 is as follows: epoxy resin and polyethylene glycol are mixed at a mass ratio of 8~6:2~4, heated to 60℃ and stirred for 1 hour, then the curing agent is added and stirred for 20~30 minutes to obtain the mixed solution.
7. The method for preparing translucent phase-change bamboo according to claim 6, characterized in that, The epoxy resin is E51.
8. The method for preparing translucent phase-change bamboo according to claim 6, characterized in that, The curing agent is obtained by mixing polyetheramine D-230 and N,N-dimethylacrylamide in a mass ratio of 9:1; the mass ratio of curing agent to epoxy resin is 3~4:7~6.
9. The method for preparing translucent phase-change bamboo according to claim 1, characterized in that, In step 4, during the vacuum impregnation process, release the pressure to atmospheric pressure for 1 minute after every 10 minutes of impregnation, and repeat the operation 3 to 5 times.
10. The method for preparing translucent phase-change bamboo according to claim 1, characterized in that, In step 4, the heating and curing process involves maintaining the temperature at 60-70℃ for 24 hours.