Preparation method of heat-storage transparent wood

Abstract

The invention provides a preparation method of heat-storage transparent wood, which comprises the following operation steps: firstly, mixing polyethylene glycol diacrylate (PEGDA) with polyethylene glycol (PEG), dipping the PEG / PEGDA mixture in different proportions into a delignified balsa wood matrix, and then quickly curing under an ultraviolet lamp to prepare the heat-storage transparent wood. According to the method, the performance of the transparent wood is improved, and the transparent wood has the advantages of being adjustable in phase change temperature and transparency at the same time, so that the application requirements of various complex indoor environments are met, and the method has huge application potential in the aspect of replacing traditional glass.

Description

Technical Field

[0001] The present invention relates to a preparation method of heat storage transparent wood, belonging to the technical field of preparation of biomass-based new materials and composite phase change energy storage materials. Background Art

[0002] In the construction industry, energy efficiency is an important driving force for material design and innovation. Adjustable transparency means that the energy consumption for indoor environment regulation can be reduced by flexibly adjusting the entry of light and heat at different times in the building. The proposal of this concept has opened up a new direction for the development of transparent materials. Solid-liquid phase change materials (PCMs) have the advantages of storing and releasing a large amount of thermal energy, improving the thermal comfort of the indoor environment, and reducing energy consumption. However, problems such as their easy leakage and limited phase change temperature adjustment range restrict their practical applications. In the fields of thermal comfort and energy applications, it is particularly important to develop materials that can adjust the phase change temperature.

[0003] Polyethylene glycol (PEG) is a common PCM. It has supercooling phenomenon. Making full use of this characteristic is expected to meet the application requirements in the complex and changeable fields of thermal comfort and energy applications. It can be concluded from some previous studies that the cross-linked network formed by polymers can, to a certain extent, solve the leakage problem of PCMs. The cross-linked network can also change parameters such as the crystallization behavior and phase change temperature of the material by restricting the degree of freedom of molecular chain movement. Cellulose, as the basic skeleton structure of wood, is a matrix with a natural three-dimensional porous structure. Incorporating the phase change material into the wood system can be a solution to solve its poor anti-leakage performance.

[0004] Transparent wood is obtained by removing part or all of the lignin in the wood and filling its microstructure with a polymer (such as polyethylene glycol diacrylate (PEGDA)) whose refractive index is close to that of cellulose, so as to reduce light scattering and increase the light transmittance while maintaining the natural texture and sustainability of the wood. The refractive index of PEGDA is similar to that of cellulose, and the cross-linked network formed after its curing is expected to adjust the phase change performance of PEG. At the same time, it has a similar long chain to PEG, which can further weaken the influence of heterogeneous nucleation and change the phase change temperature of PEG. Therefore, in the present invention, PEGDA and PEG are mixed, impregnated into delignified balsa wood, and quickly cured with an ultraviolet lamp to prepare a heat storage transparent wood suitable for adjusting the thermal comfort of indoor buildings. Summary of the Invention

[0005] The present invention addresses the problems of poor anti-leakage performance of existing composite phase change energy storage materials, limited phase change temperature adjustment range, and relatively narrow functional range of transparent wood. PEGDA and PEG are mixed and introduced into the transparent wood cross-linking system to obtain a preparation method for heat storage transparent wood. This method has a simple preparation process and low energy consumption, improves the performance of transparent wood, and enables it to have excellent properties of adjustable phase change temperature and adjustable transparency, so as to meet the application requirements of various complex indoor environments. The technical solution adopted by the present invention is: a preparation method for heat storage transparent wood, and the specific steps

[0006] are as follows:

[0007] (1) After soaking the wooden block in deionized water until it sinks to the bottom, transfer it to a NaClO2 solution for delignification treatment;

[0008] (2) Rinse the delignified wooden block repeatedly with deionized water to remove chemical agents, and then soak it in an ethanol solution and heat it until the wood becomes transparent;

[0009] (3) Add PEG to a three-necked flask and heat it at 40 - 60 °C until it is completely dissolved. Subsequently, slowly add PEGDA to the three-necked flask and stir; add a photoinitiator to the three-necked flask and stir in a dark environment;

[0010] (4) Take out the delignified balsa wood sample from the ethanol solution and, under pressure, immerse it in a PEG / PEGDA mixture with different ratios, repeatedly change the mixture, and perform multiple soaking treatments;

[0011] (5) Clamp the sample treated in (4) between two pieces of glass, cure it using an ultraviolet curing lamp, and then peel it off from the glass to obtain the heat storage transparent wood.

[0012] Preferably, in step (1), the wooden block is balsa wood with a thickness of 1 - 2 mm, the pH of the NaClO2 solution is 4 - 6, and the mass fraction is 8 - 12%.

[0013] Preferably, in step (2), the temperature of the ethanol solution is 60 - 85 °C, and it is soaked in the ethanol solution for 4 - 6 h.

[0014] Preferably, in step (3), the molecular weight of PEG is 800, and PEGDA is slowly added to the three-necked flask and stirred for 20 - 40 min.

[0015] Preferably, in step (3), the weight ratios of PEG and PEGDA are respectively set to 50 - 90%, and the addition amount of the photoinitiator is 0.5 - 2% of PEGDA.

[0016] Preferably, in step (4), the pressure treatment temperature is 40 - 60°C, the pressure is -0.08 MPa, and it is immersed in a PEG / PEGDA mixture with different ratios for 0.5 - 2 h, and the immersion treatment is carried out 2 - 4 times.

[0017] Preferably, in step (5), the curing time of the ultraviolet curing lamp is 5 - 10 min.

[0018] The present invention also provides the application of the heat storage transparent wood prepared by the preparation method described in the above technical solution as an energy-saving building material.

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

[0020] 1. The prepared material not only has excellent temperature regulation performance and adjustable optical properties, but also solves to a certain extent the problem of poor anti-leakage performance of solid-liquid phase change materials in use, and has low thermal conductivity, and has great potential in replacing traditional glass.

[0021] 2. The preparation method is simple to operate and low in energy consumption. Using delignified natural balsa wood as the matrix, PEGDA as the reinforcing phase, and encapsulating PEG into the wood matrix by the impregnation method. Cleverly utilizing the characteristics of the supercooling phenomenon of PEG, the prepared heat storage transparent wood has unique photothermal properties and has good development prospects and the value of further in-depth research and expansion. Specific implementation methods

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the following examples are used to further elaborate on the present invention in detail. It should be understood that the specific examples described here are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] The following is a detailed description of the present invention with specific implementation examples:

[0025] Comparative Example 1

[0026] (1) After soaking the balsa wood blocks with a size of 20×20×1.5 mm in deionized water until they sink to the bottom, transfer them to a 10% mass fraction of NaClO2 solution with a pH of 4.6 for delignification treatment;

[0027] (2) Rinse the delignified wood blocks repeatedly with deionized water to remove chemical agents, and then soak them in an ethanol solution and heat them, and boil them at 80°C for 4 h until the wood becomes transparent;

[0028] (3) Add PEG with a molecular weight of 800 to a three-necked flask and heat it to complete dissolution at 50°C;

[0029] (4) Take out the delignified balsa wood samples from the ethanol solution and immerse them in PEG under the conditions of 50 °C and -0.08 MPa for 1 h, and repeat the replacement of the mixture for a total of 3 times;

[0030] (5) Clamp the samples treated in (4) between two pieces of glass and cure them with an ultraviolet curing lamp at 50 °C for 10 min, and then peel them off from the glass to obtain heat storage transparent wood.

[0031] Comparative Example 2

[0032] (1) Immerse the balsa wood blocks with the size of 20×20×1.5 mm in deionized water until they sink to the bottom, and then transfer them to a 10% NaClO2 solution with a pH of 5 for delignification treatment;

[0033] (2) Rinse the delignified wood blocks repeatedly with deionized water to remove chemical agents, and then soak them in an ethanol solution and heat them, boil at 80 °C for 4 h until the wood becomes transparent;

[0034] (3) Add PEGDA into a three-necked flask and heat it to complete dissolution at 50 °C, add a photoinitiator accounting for 1% of the weight of PEGDA into the three-necked flask, and stir it in a dark environment;

[0035] (4) Take out the delignified balsa wood samples from the ethanol solution and immerse them in PEGDA under the conditions of 50 °C and -0.08 MPa for 1 h, and repeat the replacement of the mixture for a total of 3 times;

[0036] (5) Clamp the samples treated in (4) between two pieces of glass and cure them with an ultraviolet curing lamp at 50 °C for 10 min, and then peel them off from the glass to obtain heat storage transparent wood.

[0037] Example 1

[0038] (1) Immerse the balsa wood blocks with the size of 20×20×1.5 mm in deionized water until they sink to the bottom, and then transfer them to a 10% NaClO2 solution with a pH of 4.3 for delignification treatment;

[0039] (2) Rinse the delignified wood blocks repeatedly with deionized water to remove chemical agents, and then soak them in an ethanol solution and heat them, boil at 80 °C for 4 h until the wood becomes transparent;

[0040] (3) Add PEG with a molecular weight of 800 into a three-necked flask and heat it to complete dissolution at 50 °C. Subsequently, slowly add PEGDA with a weight ratio of 50% into the three-necked flask and stir for 30 min; add a photoinitiator with a weight of 1% of PEGDA into the three-necked flask and stir for 30 min in a dark environment;

[0041] (4) Take out the delignified balsa wood sample from the ethanol solution and immerse it in PEGDA at 50 °C under a pressure of -0.08 MPa for 1 h. Replace the mixture repeatedly for a total of 3 treatments;

[0042] (5) Clamp the sample treated in (4) between two pieces of glass and cure it with a UV curing lamp at 50 °C for 10 min, then peel it off from the glass to obtain heat storage transparent wood.

[0043] Example 2

[0044] (1) Immerse the balsa wood block with dimensions of 20×20×1.5 mm in deionized water until it sinks to the bottom, then transfer it to a 10% NaClO2 solution with a pH of 4.9 for delignification treatment;

[0045] (2) Rinse the delignified wood block with deionized water repeatedly to remove the chemical agents, and then soak it in an ethanol solution and heat it. Boil it at 70 °C for 4.5 h until the wood becomes transparent;

[0046] (3) Add PEG with a molecular weight of 800 into a three-necked flask and heat it to complete dissolution at 45 °C. Subsequently, slowly add PEGDA with a weight ratio of 40% into the three-necked flask and stir for 25 min; add a photoinitiator with a weight of 1.3% of PEGDA into the three-necked flask and stir for 30 min in a dark environment;

[0047] (4) Take out the delignified balsa wood sample from the ethanol solution and immerse it in PEGDA at 45 °C under a pressure of -0.08 MPa for 1.8 h. Replace the mixture repeatedly for a total of 2 treatments;

[0048] (5) Clamp the sample treated in (4) between two pieces of glass and cure it with a UV curing lamp at 50 °C for 8 min, then peel it off from the glass to obtain heat storage transparent wood.

[0049] Example 3

[0050] (1) Immerse the balsa wood block with dimensions of 20×20×1.5 mm in deionized water until it sinks to the bottom, then transfer it to a 12% NaClO2 solution with a pH of 5.8 for delignification treatment;

[0051] (2) The delignified wood blocks were repeatedly rinsed with deionized water to remove the chemical agents, and then soaked in an ethanol solution and heated. They were boiled at 75 °C for 6 h until the wood became transparent.

[0052] (3) PEG with a molecular weight of 800 was added to a three-necked flask and heated to complete dissolution at 55 °C. Subsequently, PEGDA with a weight ratio of 30% was slowly added to the three-necked flask and stirred for 25 min. A photoinitiator with a weight of 1.7% of PEGDA was added to the three-necked flask and stirred in the dark for 30 min.

[0053] (4) The delignified balsa wood samples were taken out of the ethanol solution and immersed in PEGDA at 60 °C under a pressure of -0.08 MPa for 0.7 h. The mixture was repeatedly changed and the treatment was carried out 3 times in total.

[0054] (5) The samples treated in (4) were clamped between two pieces of glass and cured with a UV curing lamp at 50 °C for 8 min, and then peeled off from the glass to obtain the heat storage transparent wood.

[0055] Example 4

[0056] (1) Balsa wood blocks with dimensions of 20×20×1.5 mm were soaked in deionized water until they sank to the bottom, and then transferred to a NaClO2 solution with a pH of 5.1 and a mass fraction of 12% for delignification treatment.

[0057] (2) The delignified wood blocks were repeatedly rinsed with deionized water to remove the chemical agents, and then soaked in an ethanol solution and boiled at 80 °C for 4 h until the wood became transparent.

[0058] (3) PEG with a molecular weight of 800 was added to a three-necked flask and heated to complete dissolution at 45 °C. Subsequently, PEGDA with a weight ratio of 20% was slowly added to the three-necked flask and stirred for 40 min. A photoinitiator with a weight of 1.5% of PEGDA was added to the three-necked flask and stirred in the dark for 40 min.

[0059] (4) The delignified balsa wood samples were taken out of the ethanol solution and immersed in PEGDA at 50 °C under a pressure of -0.08 MPa for 1 h. The mixture was repeatedly changed and the treatment was carried out 3 times in total.

[0060] (5) The samples treated in (4) were clamped between two pieces of glass and cured with a UV curing lamp at 50 °C for 10 min, and then peeled off from the glass to obtain the heat storage transparent wood.

[0061] Example 5

[0062] (1) After soaking a balsa wood block with dimensions of 20×20×1.5 mm until it sinks to the bottom in deionized water, it is transferred to a NaClO2 solution with a pH of 4.7 and a mass fraction of 12% for delignification treatment;

[0063] (2) The delignified wood block is repeatedly rinsed with deionized water to remove chemical agents, then soaked in an ethanol solution, and boiled at 85 °C for 5 h until the wood becomes transparent;

[0064] (3) PEG with a molecular weight of 800 is added to a three-necked flask and heated to complete dissolution at 50 °C. Subsequently, PEGDA with a weight ratio of 10% is slowly added to the three-necked flask and stirred for 30 min; A photoinitiator with a weight of 1.3% of PEGDA is added to the three-necked flask and stirred for 37 min in a dark environment;

[0065] (4) The delignified balsa wood sample is taken out from the ethanol solution and immersed in PEGDA at 50 °C under a pressure of -0.08 MPa for 1.3 h, and the mixture is repeatedly replaced for a total of 3 treatments;

[0066] (5) The sample treated in (4) is clamped between two pieces of glass and cured with an ultraviolet curing lamp at 50 °C for 10 min, and then peeled off from the glass to obtain heat storage transparent wood.

[0067] The thermal properties of the above 7 groups of samples (Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3, Example 4, Example 5) were measured under nitrogen conditions using a differential scanning calorimeter (DSC, DSC50, USA). The parameter settings were as follows: A sample of 5.00±0.50 mg was cooled from 70 °C to -10 °C at a cooling rate of 5 °C / min and heated from -10 °C to 50 °C at a heating rate of 5 °C / min. The haze meter was used to measure the light transmittance of the samples at 10 °C and 35 °C respectively. The test results are shown in Table 1.

[0068] Table 1 Summary of Thermal and Optical Properties of Series of Heat Storage Transparent Wood

[0069] Category Melting temperature Latent heat Condensation temperature Latent heat Transmittance at 10°C Transmittance at 35°C Comparative Example 1 31.20℃ 106.8 J / g 20.1℃ 106.4 J / g 25.80％ 36.40％ Comparative Example 2 —— —— —— —— 89.10％ 89.30％ Example 1 29.62℃ 47.9 J / g 12.96℃ 48.1 J / g 54.60％ 80.60％ Example 2 29.61℃ 60.1 J / g 15.47℃ 60.6 J / g 53.80％ 79.20％ Example 3 29.72℃ 72.9 J / g 16.38℃ 72.3 J / g 52.60％ 78.80％ Example 4 29.51℃ 84.2 J / g 18.35℃ 84.0 J / g 52.80％ 77.20％ Example 5 29.74℃ 96.3 J / g 18.85℃ 95.8 J / g 48.20％ 77.10％

[0070] Summarizing Table 1, it can be seen that the melting temperature and condensation temperature of Comparative Example 1 are 31.2 °C and 20.1 °C respectively; the latent heat is 106.8 J / g, the light transmittance at 10 °C is 25.8%, and the light transmittance at 35 °C is 36.4%; the light transmittance of Comparative Example 2 at 10 °C is 89.1%, and the light transmittance at 35 °C is 89.3%. In the series of examples, the melting temperature is close to 30 °C, the condensation temperature can be adjusted to 12.96 - 18.85 °C, and the phase change latent heat is 47.9 - 96.3 J / g. Compared with Comparative Example 1, its thermal properties are more suitable for scenarios requiring temperature regulation; the adjustable range of transparency is 48 - 80%, combining the light regulation ranges of Comparative Examples 1 and 2 with only PEG and PEGDA added. These excellent properties make this material have broad application prospects in application fields such as energy-saving building materials and smart windows that require temperature regulation and light switching.

[0071] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing heat-storage transparent wood, characterized in that: The steps include: (1) After the wood blocks are soaked in deionized water and settled to the bottom, they are transferred to a NaClO2 solution for delignification treatment; (2) The delignified wood blocks are repeatedly rinsed with deionized water to remove the chemical agents, and then immersed in an ethanol solution and heated until the wood is translucent; (3) adding polyethylene glycol (PEG) into a three-necked flask and heating at 40-60° C. until completely dissolved, then slowly adding polyethylene glycol diacrylate (PEGDA) into the three-necked flask and stirring; adding a photoinitiator into the three-necked flask and stirring in a dark environment; (4) taking out the delignified balsa wood sample from the ethanol solution and immersing it in a mixture of PEG / PEGDA with different ratios under pressure, repeatedly changing the mixture and performing multiple immersion treatments; (5) The sample treated in (4) is sandwiched between two sheets of glass, cured using an ultraviolet curing lamp, and then peeled off from the glass to obtain heat-storage transparent wood.

2. The preparation method according to claim 1, characterized in that: In the step (1), the wood block is balsa wood with a thickness of 1-2 mm, and the pH value of the NaClO2 solution is 4-6, and the mass fraction is 8-12%.

3. The preparation method according to claim 1, characterized in that: In the step (2), the temperature of the ethanol solution is 60-85° C., and the sample is immersed in the ethanol solution for 4-6 hours.

4. The preparation method according to claim 1, characterized in that: In the step (3), the molecular weight of PEG is 800, and PEGDA is slowly added into a three-necked flask and stirred for 20-40 minutes.

5. The preparation method according to claim 1, characterized in that: In the step (3), the weight ratio of PEG to PEGDA is set to 50-90%, and the amount of photoinitiator added is 0.5-2% of PEGDA.

6. The preparation method according to claim 1, characterized in that: In the step (4), the pressure treatment temperature is 40-60°C, the pressure is -0.08MPa, and the mixture is immersed in a PEG / PEGDA mixture of different proportions for 0.5-2h, and the immersion treatment is performed 2-4 times.

7. The preparation method according to claim 1, characterized in that: In the step (5), the curing time of the UV curing lamp is 5-10 minutes.

8. A heat-storing transparent wood, characterized in that: The method is prepared by any one of claims 1 to 7.

9. Use of the heat-storage transparent wood according to claim 8 as an energy-saving building material.