阅读说明：本技术 一种相变储能木材的制备方法 (Preparation method of phase-change energy-storage wood ) 是由 孙伟圣 王文斌 郭玺 曹惠敏 刘静怡 贾世芳 于 2019-09-24 设计创作，主要内容包括：本发明公开了一种相变储能木材的制备方法,按下述步骤进行：将木材放入氢氧化钠和亚硫酸钠混合溶液中,再将溶液煮沸保持12-48h,直至溶液颜色不发生变化；将煮好的木材放入去离子水中再次煮沸的4-10h,中间更换去离子水,维持去离子水的pH为6-8；c、将去离子水中的木材捞出,放入浓度为90-100％的乙醇溶液中2-6h；再将木材浸渍在固含量为15-40％的相变微胶囊乳液中,在真空度为0.05-0.2MPa的条件下浸渍0.5-2h；浸渍的同时,分别朝木材的横向面和纵向面施加微波辐射；取出浸渍好的木材后在温度为25-40℃下干燥72-120h,得到相变储能木材。本发明制备的相变储能木材具备较大的相变热焓值以及优异的稳定性,热循环耐久性较好,使用寿命长,而且相变微胶囊在木材中的渗透性好,分布均匀。(The invention discloses a preparation method of phase change energy storage wood, which comprises the following steps: putting wood into a mixed solution of sodium hydroxide and sodium sulfite, boiling the solution for 12-48h until the color of the solution is not changed; putting the boiled wood into deionized water for boiling again for 4-10h, replacing the deionized water in the middle, and maintaining the pH value of the deionized water to be 6-8; c. fishing out the wood in the deionized water, and putting the wood in 90-100% ethanol solution for 2-6 h; then, soaking the wood in the phase-change microcapsule emulsion with the solid content of 15-40% for 0.5-2h under the condition that the vacuum degree is 0.05-0.2 MPa; applying microwave radiation to the transverse surface and the longitudinal surface of the wood respectively while impregnating; and taking out the impregnated wood, and drying at the temperature of 25-40 ℃ for 72-120h to obtain the phase change energy storage wood. The phase change energy storage wood prepared by the invention has the advantages of large phase change enthalpy value, excellent stability, good thermal cycle durability, long service life, good permeability of the phase change microcapsules in the wood and uniform distribution.)

1. A preparation method of phase change energy storage wood is characterized by comprising the following steps: the method comprises the following steps:

a. putting wood into a mixed solution of sodium hydroxide and sodium sulfite, boiling the solution for 12-48h until the color of the solution is not changed;

b. boiling the boiled wood in deionized water for 4-10h again, replacing the deionized water in the middle, and maintaining the pH value of the deionized water to be 6-8;

c. fishing out the wood in the deionized water, and putting the wood in 90-100% ethanol solution for 2-6 h;

d. then, soaking the wood in the phase-change microcapsule emulsion with the solid content of 15-40% for 0.5-2h under the condition that the vacuum degree is 0.05-0.2 MPa; applying 500MHz-600MHz microwave radiation to the transverse surface of the wood and 400MHz-500MHz microwave radiation to the longitudinal surface of the wood while impregnating;

e. and taking out the impregnated wood, and drying at the temperature of 25-40 ℃ for 72-120h to obtain the phase change energy storage wood.

2. The method for preparing phase change energy storage wood according to claim 2, wherein: the method comprises the following steps:

a. putting wood into a mixed solution of sodium hydroxide and sodium sulfite, boiling the solution for 12-48h until the color of the solution is not changed;

b. putting the boiled wood into deionized water for boiling again for 4-10h, replacing the deionized water for many times in the middle, and maintaining the pH value of the deionized water to be 7;

c. fishing out the wood in the deionized water, and putting the wood in 95% ethanol solution for 3 hours;

d. then, soaking the wood in the phase-change microcapsule emulsion with the solid content of 30% for 1h under the condition that the vacuum degree is 0.1 MPa; applying 550MHz microwave radiation to the transverse side of the wood and 450MHz microwave radiation to the longitudinal side of the wood while impregnating;

e. and taking out the impregnated wood, and drying at the temperature of 35 ℃ for 96 hours to obtain the phase change energy storage wood.

3. The method for preparing phase change energy storage wood according to claim 1 or 2, wherein: in the step a, the concentration of sodium hydroxide in the mixed solution of sodium hydroxide and sodium sulfite is 2.2-3.0mol/L, and the mass ratio is 15-50%; the concentration of the sodium sulfite in the mixed solution of the sodium hydroxide and the sodium sulfite is 0.2-0.8mol/L, and the mass ratio is 10-50%.

4. The method for preparing phase change energy storage wood according to claim 1 or 2, wherein: in the step d, the vacuum is released once every 10-20min during the vacuum impregnation, and the impregnation is carried out by vacuumizing again after the normal pressure is recovered.

5. The method for preparing phase change energy storage wood according to claim 1 or 2, wherein: and c, soaking the wood soaked in the step c in 45-60% sodium silicate solution for 0.5-1 h.

Technical Field

The invention relates to the technical field of phase change materials and wood processing, in particular to a preparation method of phase change energy storage wood.

Background

The phase-change material is a material which has phase change near a phase-change temperature, absorbs or releases a large amount of heat and keeps the temperature of the material unchanged, so that the phase-change material is widely applied to the fields of energy conservation, solar energy development, electronic equipment and the like. Phase change materials are mainly classified into solid-liquid, solid-solid, and liquid-vapor phase change materials according to a phase change state, and among them, the solid-liquid phase change materials have advantages of high latent heat, appropriate temperature, and the like compared with other two kinds, and thus are most widely used. However, since the solid-liquid phase change material has disadvantages of volume change, leakage, and the like during the phase change process, the heat storage capacity of the solid-liquid phase change material is reduced, and environmental pollution is caused, so how to solve the problems of volume change, leakage, and the like of the solid-liquid phase change material becomes a hot point of research in recent years. The microcapsule technology is a technology for wrapping trace substances in a polymer shell, is a micro-packaging technology for storing solid, liquid and gas, can wrap phase-change materials by utilizing the microcapsule technology to prepare phase-change microcapsules, and can obtain phase-change microcapsule emulsion by adding the microcapsules into deionized water for ultrasonic dispersion. The phase change microcapsule can prevent the phase change material from leaking in the phase change process to the maximum extent, reduce the volume change, increase the heat conduction area and improve the heat conduction efficiency.

Wood is a natural porous material with high strength to weight ratio, good acoustical and aesthetic properties, and good processability, and has been used as a building material and a furniture construction material for thousands of years. The porous wood is utilized, and the modifying agent is injected into the wood under certain pressure and temperature, so that more functions such as corrosion prevention, mildew prevention, flame retardant and the like can be given to the wood. In the prior art, in order to achieve the purpose of controlling the indoor temperature, one mode is to rely on foreign objects to work, such as air conditioning, ice block placement, water spraying and cooling and the like, the air conditioning consumes a large amount of energy sources such as electric energy and the like, the energy conservation and emission reduction are not facilitated, the temperature regulation in the modes of ice block spraying and the like is unstable, and the air conditioning is not suitable for home application, and the other mode is to carry out heat preservation through building materials, such as application of heat preservation materials and the like, but the heat preservation materials are high in cost, complex in manufacturing process and short in. Chinese application No. CN107511900A discloses a method for preparing thermochromic phase change energy storage wood from delignified wood, which comprises the following steps: (1) adding the wood blocks into a mixed solution of sodium hydroxide and sodium sulfite, heating to boil and keeping for a certain time, and then washing with deionized water to obtain delignified wood; (2) adding delignified wood into a hydrogen peroxide solution for bleaching, and heating to boil until the wood is whitened; (3) adding crystal violet lactone and bisphenol A into molten tetradecanol, and magnetically stirring under a heating condition to obtain a compound; (4) and (3) putting the delignified wood into the compound for dipping, and putting the delignified wood into a vacuum oven for a certain time to obtain the thermochromic phase change energy storage wood. The thermochromic phase-change energy storage wood prepared by the method can be used for regulating the indoor temperature, wherein the indoor temperature regulation is carried out through the phase-change energy storage of the compound, but the method cannot effectively permeate the compound into the wood, and the compound is easy to run off, so that the problem of short service life of the phase-change energy storage wood is caused.

Disclosure of Invention

The invention aims to provide a preparation method of phase change energy storage wood. The phase change energy storage wood prepared by the invention has the advantages of large phase change enthalpy value, excellent stability, good thermal cycle durability, long service life, good permeability of the phase change microcapsules in the wood and uniform distribution.

The technical scheme of the invention is as follows: the preparation method of the phase change energy storage wood comprises the following steps:

a. putting wood into a mixed solution of sodium hydroxide and sodium sulfite, boiling the solution for 12-48h until the color of the solution is not changed;

b. putting the boiled wood into deionized water for boiling again for 4-10h, replacing the deionized water in the middle, and maintaining the pH value of the deionized water to be 6-8;

c. fishing out the wood in the deionized water, and putting the wood in 90-100% ethanol solution for 2-6 h;

d. then, soaking the wood in the phase-change microcapsule emulsion with the solid content of 15-40% for 0.5-2h under the condition that the vacuum degree is 0.05-0.2 MPa; applying 500MHz-600MHz microwave radiation to the transverse surface of the wood and 400MHz-500MHz microwave radiation to the longitudinal surface of the wood while impregnating;

e. and taking out the impregnated wood, and drying at the temperature of 25-40 ℃ for 72-120h to obtain the phase change energy storage wood.

The preparation method of the phase change energy storage wood comprises the following steps:

a. putting wood into a mixed solution of sodium hydroxide and sodium sulfite, boiling the solution for 12-48h until the color of the solution is not changed;

b. putting the boiled wood into deionized water for boiling again for 4-10h, replacing the deionized water for many times in the middle, and maintaining the pH value of the deionized water to be 7;

c. fishing out the wood in the deionized water, and putting the wood in 95% ethanol solution for 3 hours;

d. then, soaking the wood in the phase-change microcapsule emulsion with the solid content of 30% for 1h under the condition that the vacuum degree is 0.1 MPa; applying 550MHz microwave radiation to the transverse side of the wood and 450MHz microwave radiation to the longitudinal side of the wood while impregnating;

e. and taking out the impregnated wood, and drying at the temperature of 35 ℃ for 96 hours to obtain the phase change energy storage wood.

In the preparation method of the phase change energy storage wood, in the step a, the concentration of sodium hydroxide in the mixed solution of sodium hydroxide and sodium sulfite is 2.2-3.0mol/L, and the mass ratio is 15-50%; the concentration of the sodium sulfite in the mixed solution of the sodium hydroxide and the sodium sulfite is 0.2-0.8mol/L, and the mass ratio is 10-50%.

In the step d, the vacuum is released once every 10-20min during the vacuum impregnation, and then the impregnation is performed by vacuumizing again.

In the preparation method of the phase change energy storage wood, the wood impregnated in the step c is further impregnated in 45-60% sodium silicate solution for 0.5-1 h.

Compared with the prior art, the invention improves and optimizes the process and parameters compared with the prior art, such as Chinese patent application with publication number CN107511900A, enlarges the intercellular space of the wood by removing partial lignin of the wood, increases the aperture of the micropore, and facilitates the impregnation and filling of the phase-change microcapsule emulsion; the wood is soaked in the phase-change microcapsule emulsion for treatment under the condition that the vacuum degree is 0.05-0.2MPa, and the vacuum impregnation is adopted, so that air in wood cells can be pumped out, the phase-change microcapsule emulsion can conveniently permeate into the wood cells, and the wood can fully absorb the phase-change microcapsule emulsion for subsequent phase-change energy storage; during vacuum impregnation, the microwave radiation of 500MHz-600MHz is applied to the transverse surface of the wood, the microwave radiation of 400MHz-500MHz is applied to the longitudinal surface of the wood, the shape of the wood tissue is changed by the microwave radiation, and a large number of cavities are formed between cell gaps, so that the phase-change microcapsule emulsion enters the wood through the cavities and is fully absorbed, and meanwhile, as the microwave radiation has propagation energy, the transverse and longitudinal microwave radiation is applied to vibrate in different directions, so that the phase-change microcapsule emulsion can be pushed and driven to uniformly diffuse in gaps such as ducts, sieve tubes, cell pores and the like of the wood, phase-change energy-storage microcapsules can be further fully filled in the wood, and the phase-change energy-storage wood with proper phase-change temperature, large latent heat and high stability can be obtained. The phase change energy storage wood prepared by the invention has a larger phase change enthalpy value; the test shows that the weight loss of the invention is only 4.5 wt% below 100 ℃, the invention has excellent thermal stability, the phase transition temperature range is 25-29 ℃, and the invention is suitable for indoor temperature regulation; after 100 times of cold-hot circulation, the initial temperature change range of the phase change energy storage wood is small, the enthalpy value is stable, and the heat circulation durability is excellent; the invention has long service life, simple preparation method and low cost, is suitable for large-area popularization, and has important significance for adjusting indoor temperature and realizing building energy conservation. In addition, the wood impregnated by the ethanol solution is put into the sodium silicate solution for impregnation, the sodium silicate has adhesive force, the wood can adsorb the sodium silicate after being impregnated into the sodium silicate solution, then the phase change energy storage microcapsules are strongly adsorbed in the wood through the adhesive force, and the wood is solidified through the subsequent drying process, and the solidified sodium silicate can be attached to the surface of a pore channel, so that the phase change energy storage microcapsules captured by the sodium silicate have strong leaching resistance, and the stability and the durability of the phase change energy storage wood are finally improved. And due to the curing effect of the sodium silicate, the density and the strength of the energy storage wood can be improved, the weather resistance of the energy storage wood is enhanced, and the service life of the energy storage wood is greatly prolonged. The method is used for removing the vacuum once every 10-20min during vacuum impregnation, and vacuumizing again for impregnation after normal pressure is recovered, so that bubbles in the wood can be eliminated, and the phenomenon that the phase change energy storage microcapsule emulsion cannot permeate continuously due to bubble blockage of the phase change energy storage microcapsule emulsion cup is prevented, and thus the permeability of the phase change energy storage microcapsule emulsion can be further enhanced.

Drawings

FIG. 1 shows the shape and particle size of a phase change energy storage microcapsule in a phase change energy storage wood;

FIG. 2 is a diagram showing the pore size of the phase change energy storage wood;

FIG. 3 is a Differential Scanning Calorimeter (DSC) graph;

fig. 4 is a thermogravimetric analyzer (TG) graph.

Detailed Description

The present invention is further described with reference to the following drawings and examples, but the invention is not limited thereto, and the scope of the invention should include the full contents of the claims, and the invention can be more fully understood by those skilled in the art through the following examples.

The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.