阅读说明：本技术 一种石墨烯基多重响应的定型复合相变材料及制备和应用 (Graphene-based multi-response shaped composite phase change material and preparation and application thereof ) 是由 史全 孙克衍 于 2020-05-22 设计创作，主要内容包括：本发明属于定型复合相变材料领域,特别涉及一种石墨烯基多重响应的定型复合相变材料及制备和应用,具体以下工艺步骤：(1)将氧化石墨烯分散液超声形成均匀悬浊液；然后加入钼酸铵和硫脲,磁力搅拌形成稳定混合液；将混合液置于水热釜中反应形成复合石墨烯气凝胶；然后将复合气凝胶通过冷冻干燥制得最终的复合石墨烯气凝胶载体。(2)将相变材料与(1)中得到的载体混合,置于真空烘箱中使相变材料充分进入到载体结构中,除去表面多余的相变材料后,制得多重响应的石墨烯基定型复合相变材料。本发明制得的石墨烯基多重响应的定型复合相变材料为黑色块状物,具有定型效果好,相变材料负载量高,相变焓大,循环性能好等优点,同时该体系具有强吸光和导电性,可以将光能,电能转化为热能进行储存,可用于热能转化与储存领域。(The invention belongs to the field of shaped composite phase change materials, and particularly relates to a graphene-based multi-response shaped composite phase change material, and preparation and application thereof, wherein the method specifically comprises the following process steps: (1) carrying out ultrasonic treatment on the graphene oxide dispersion liquid to form a uniform suspension; then adding ammonium molybdate and thiourea, and magnetically stirring to form a stable mixed solution; placing the mixed solution in a hydrothermal kettle for reaction to form composite graphene aerogel; and then, carrying out freeze drying on the composite aerogel to obtain the final composite graphene aerogel carrier. (2) And (3) mixing the phase-change material with the carrier obtained in the step (1), putting the mixture into a vacuum oven to enable the phase-change material to fully enter a carrier structure, and removing redundant phase-change materials on the surface to obtain the multi-response graphene-based shaped composite phase-change material. The graphene-based multi-response shaped composite phase-change material prepared by the invention is a black block, has the advantages of good shaping effect, high phase-change material load, large phase-change enthalpy, good cycle performance and the like, has strong light absorption and electric conductivity, can convert light energy and electric energy into heat energy for storage, and can be used in the field of heat energy conversion and storage.)

1. A preparation method of a graphene-based multi-response shaped composite phase change material is characterized by comprising the following specific process steps:

(1) ultrasonically treating the graphene oxide aqueous dispersion to form a uniform turbid liquid; then adding ammonium molybdate and thiourea, and magnetically stirring to form a stable mixed solution; placing the mixed solution in a hydrothermal kettle for reaction to form composite graphene aerogel; then, freeze-drying the composite aerogel to obtain a final composite graphene aerogel carrier;

(2) and (2) mixing the phase-change material with the carrier obtained in the step (1), putting the mixture into a vacuum oven to enable the phase-change material to fully enter a carrier structure, and removing redundant phase-change material on the surface to obtain the graphene-based sizing composite phase-change material.

2. The method of claim 1, wherein: the concentration of the graphene oxide dispersion liquid in the step (1) is 2-10g/L, the preferable range is 5-10g/L, and the reaction effect is best when the concentration is 6 g/L.

3. The production method according to claim 1 or 2, characterized in that: the mass ratio of ammonium molybdate to graphene oxide in the mixed solution stabilized in the step (1) is graphene oxide: ammonium molybdate is 0.1-2, preferably in the range of 0.4-1.2, and when the ratio is 0.5, the reaction effect is the best;

the mass ratio of ammonium molybdate to thiourea in the stable mixed solution in the step (1) is ammonium molybdate: thiourea is 0.025 to 0.2, preferably in the range of 0.04 to 0.1, and the reaction effect is most excellent when the ratio is 0.05.

4. The method of claim 1, wherein: the ultrasonic time required for forming the graphene dispersion liquid in the step (1) is 2-4h, and the reaction effect is optimal when the time is 4 h;

the magnetic stirring time for forming the stable mixed solution in the step (1) is 10-30min, and when the time is 30min, the reaction effect is optimal.

5. The method of claim 1, wherein: the reaction temperature of the reaction kettle in the step (1) is 150-180 ℃, the reaction time is 24-36h, the preferred range is 24-30h, and when the temperature is 180 ℃ and the reaction time is 24h, the reaction effect is optimal;

the freeze-drying temperature in the step (1) is-20 ℃ to-5 ℃, the time is 48 to 72 hours, the preferable range is 48 to 60 hours, and when the temperature is-10 ℃ and the time is 48 hours, the freeze-drying effect is optimal.

6. The method of claim 1, wherein: the phase-change material in the step (2) is one or more than two of paraffin, polyethylene glycol, fatty alcohol and fatty acid; the mass ratio of the phase-change material in the product to the carrier obtained in the step (1) is 3-10.

7. The method of claim 1, wherein: the set temperature of the vacuum oven in the step (2) is 80-100 ℃, the vacuum degree is-0.06 MPa-0.1 MPa, the preferred range is-0.08 MPa-0.1 MPa, and the best effect is achieved when the temperature is 80 ℃ and the vacuum degree is-0.1 MPa;

the vacuum impregnation time in the step (2) is 2-4h, and the effect is optimal when the vacuum impregnation time is 4 h.

8. The composite phase-change material prepared by the preparation method of any one of claims 1 to 7, which is characterized in that: the finally prepared graphene-based multi-response shaped composite phase change material is a black massive solid.

9. The composite phase change material of claim 8, wherein: the multiple response means that the light energy and the electric energy can be simultaneously responded and converted into heat energy;

the finally prepared graphene-based multi-response shaped composite phase change material has strong light absorption capacity;

the finally prepared graphene-based multi-response shaped composite phase change material can conduct electricity;

the finally prepared graphene-based multi-response shaped composite phase change material can convert light energy and/or electric energy into heat energy for storage.

10. Use of the composite phase change material according to claim 8 or 9, wherein: the product may be used as a phase change material for thermal energy conversion and/or storage.

Technical Field

The invention belongs to the field of shaped composite phase change materials, and particularly relates to a preparation method for synthesizing a graphene-based shaped composite phase change material capable of being used as multiple responses for heat energy conversion and storage through hydrothermal reaction, freeze drying and vacuum impregnation.

Background

The human development and social progress lead to the increasing consumption rate of resources, and the energy crisis problem caused by the increase of the consumption rate is in urgent need to be solved. Improving the utilization rate of energy is an important way to solve the energy problem. Thermal energy is an important energy source closely related to human life, and the improvement of the utilization rate is beneficial to reducing energy consumption. The phase-change material is used as a core functional material of a thermal energy storage system, and the research is deep, and the performance improvement is important for improving the thermal energy storage efficiency.

With the research and development of phase-change materials, the interconversion between heat energy and other environmental energy sources becomes a hot spot of research in the field. Solar energy is the most abundant natural energy, and is an important aspect in the field of heat energy conversion when steam is converted into heat energy and stored; in addition, the reasonable utilization of electric energy in different periods and the conversion of the electric energy into heat energy are important aspects for researching the conversion of the heat energy. However, the insensitivity of the phase change material itself to light and the insulation are problems that must be solved in the thermal energy conversion process.

According to the invention, graphene oxide, ammonium molybdate and thiourea are used as raw materials, different proportions of the graphene oxide, the ammonium molybdate and the thiourea are regulated, a composite graphene aerogel carrier is obtained through hydrothermal reaction and freeze drying, and then a phase-change material is immersed in the composite graphene aerogel carrier through vacuum impregnation to finally obtain the multi-response shaped composite phase-change material. In the product, the phase-change material has high load, excellent heat storage performance and shape stability, and in addition, the system can respond to light energy and electric energy and convert the light energy and the electric energy into heat energy for storage, and the system shows excellent heat energy conversion and storage capacity.

Disclosure of Invention

The invention provides a graphene-based multi-response shaped composite phase change material which is prepared by taking graphene oxide, ammonium molybdate and thiourea as raw materials, performing hydrothermal reaction, freeze-drying to obtain a composite graphene aerogel carrier, and then immersing a phase change material in the carrier through vacuum impregnation.

The synthesized graphene-based multi-response shaped composite phase change material comprises the following steps:

(1) carrying out ultrasonic treatment on graphene oxide aqueous dispersion with a certain concentration for a certain time to form uniform turbid liquid; then adding ammonium molybdate and thiourea with certain mass, and magnetically stirring for a certain time to form a stable mixed solution; placing the mixed solution in a hydrothermal kettle, and reacting at a certain temperature for a certain time to form composite graphene aerogel; and then, carrying out freeze drying on the composite aerogel at a certain temperature for a certain time to obtain the final composite graphene aerogel carrier.

(2) Mixing the phase-change material with the carrier obtained in the step (1), putting the mixture into a vacuum oven to enable the phase-change material to fully enter a carrier structure, and removing redundant phase-change material on the surface to obtain the graphene-based shaped composite phase-change material.

Further, the multiple responses mean that the light energy and the electric energy can be simultaneously responded and converted into the heat energy.

Further, raw materials for constructing the graphene composite aerogel are graphene oxide, ammonium molybdate and thiourea.

Further, the concentration of the graphene oxide dispersion liquid in the step (1) is 2-10 g/L.

Further, the mass ratio of ammonium molybdate to graphene oxide in the mixed solution stabilized in the step (1) is graphene oxide: ammonium molybdate 0.1-2.

Further, the mass ratio of ammonium molybdate to thiourea in the stable mixed solution in the step (1) is ammonium molybdate: 0.025-0.2 parts of thiourea.

Further, the ultrasonic time required for forming the graphene dispersion liquid in the step (1) is 2-4 h.

Further, the magnetic stirring time for forming the stable mixed solution in the step (1) is 10-30 min.

Further, the reaction temperature of the reaction kettle in the step (1) is 150-180 ℃, and the reaction time is 24-36 h.

Further, the freeze-drying temperature in the step (1) is-20 ℃ to-5 ℃, and the time is 48-72 h.

Further, the phase-change material in the step (2) is one or more than two of paraffin, polyethylene glycol, fatty alcohol and fatty acid; the mass ratio of the phase-change material in the product to the carrier obtained in the step (1) is 3-10;

further, the set temperature of the vacuum oven in the step (2) is 80-100 ℃, and the vacuum degree is-0.06 MPa-0.1 MPa.

Further, the vacuum impregnation time in the step (2) is 2-4 h.

The design reaction condition of the invention has low requirement on pressure and temperature, the operation is simple and convenient, the prepared graphene-based multi-response shaped composite phase-change material is a black block, and the invention has the advantages of good shaping effect, high phase-change material load, large phase-change enthalpy, good cycle performance and the like, and meanwhile, the system has strong light absorption and electric conductivity, can convert light energy and electric energy into heat energy for storage, and can be used in the field of heat energy conversion and storage.

Drawings

Fig. 1 differential scanning calorimetry curve of graphene aerogel/paraffin (90%).

Fig. 2 absorbance curve of graphene aerogel/octadecanol (80%).

Fig. 3 electrothermal conversion curve (current 0.15A) of graphene aerogel/paraffin (80%).

Detailed Description

Example 1

(1) Taking 0.12g of graphene oxide in 20mL of distilled water, and carrying out ultrasonic treatment for 2h to form a uniform suspension; then 0.2g of ammonium molybdate and 1g of thiourea are added, and the mixture is magnetically stirred for 30min to form a stable mixed solution; then transferring the mixed solution into a reaction kettle, and reacting at 180 ℃ for 24 hours to obtain the composite graphene aerogel; and then placing the aerogel in a freeze dryer, setting the temperature to be-10 ℃, and freeze-drying for 48 hours to obtain the graphene aerogel carrier.

(2) Adding a proper amount of paraffin (the mass ratio of the paraffin to the graphene carrier is 20: 1) into the carrier in the step (1), and placing the carrier in a vacuum oven, wherein the vacuum degree is-0.1 MPa, and the temperature is 80 ℃ for dipping for 3 hours. And removing redundant paraffin on the surface to finally obtain the graphene-based multi-response sizing composite phase change material.

The graphene-based multiple-response shaping composite phase change material is a black block, wherein the mass percent of paraffin accounts for about 90%, and the loading amount is high; the leakage is avoided in the heating process, and the shaping effect is good; after 100 heating and cooling cycles (heating to 80 ℃, cooling to 0 ℃, and the cycle), the phase change performance is almost unchanged, and the cycle performance is good; the absorbance is 1.0-1.8, and the light absorption capacity is strong; and the composite material may be electrically conductive; the material can convert light and electric energy into heat energy for storage; the differential scanning calorimetry curve is shown in figure 1;

example 2

(1) Taking 0.16g of graphene oxide in 20mL of distilled water, and carrying out ultrasonic treatment for 2h to form a uniform suspension; then 0.16g of ammonium molybdate and 1.6g of thiourea are added, and the mixture is magnetically stirred for 30min to form a stable mixed solution; then transferring the mixed solution into a reaction kettle, and reacting at 180 ℃ for 24 hours to obtain the composite graphene aerogel; and then placing the aerogel in a freeze dryer, setting the temperature to be-10 ℃, and freeze-drying for 48 hours to obtain the graphene aerogel carrier.

(2) Adding a proper amount of octadecanol (the mass ratio of the octadecanol to the graphene carrier is 20: 1) into the carrier in the step (1), and placing the carrier in a vacuum oven, wherein the vacuum degree is-0.1 MPa, and the temperature is 80 ℃ for soaking for 2 hours. And removing redundant paraffin on the surface to finally obtain the graphene-based multi-response sizing composite phase change material.

The graphene-based multiple-response shaped composite phase change material is a black block, wherein the mass percent of octadecanol accounts for about 80%, and the loading amount is high; the leakage is avoided in the heating process, and the shaping effect is good; after 100 heating and cooling cycles (heating to 80 ℃, cooling to 0 ℃, and circulating the cycles), the phase change performance is almost unchanged, the cycle performance is good, the absorbance is 1.0-1.8, and the light absorption capacity is strong; and the composite material may be electrically conductive; the material can convert light and electric energy into heat energy for storage; the absorbance curve is shown in figure 1;

example 3

(1) Taking 0.2g of graphene oxide in 20mL of distilled water, and carrying out ultrasonic treatment for 3h to form a uniform suspension; then 0.2g of ammonium molybdate and 1.8g of thiourea are added, and the mixture is magnetically stirred for 30min to form a stable mixed solution; then transferring the mixed solution into a reaction kettle, and reacting at 180 ℃ for 24 hours to obtain the composite graphene aerogel; and then placing the aerogel in a freeze dryer, setting the temperature to be-10 ℃, and freeze-drying for 48 hours to obtain the graphene aerogel carrier.

(2) Adding a proper amount of paraffin (the mass ratio of the paraffin to the graphene carrier is 20: 1) into the carrier in the step (1), and placing the carrier in a vacuum oven, wherein the vacuum degree is-0.1 MPa, and the temperature is 80 ℃ for soaking for 2 hours. And removing redundant paraffin on the surface to finally obtain the graphene-based multi-response sizing composite phase change material.

The graphene-based multiple-response shaping composite phase change material is a black block, wherein the mass percent of paraffin accounts for about 80%, and the loading amount is high; the leakage is avoided in the heating process, and the shaping effect is good; after 100 heating and cooling cycles (heating to 80 ℃, cooling to 0 ℃, and circulating) the phase change performance is almost unchanged, the cycle performance is good, the absorbance is 1.0-1.8, and the light absorption capacity is strong; and the composite material may be electrically conductive; the material can convert light and electric energy into heat energy for storage; the electrothermal conversion curve (0.18A) is shown in FIG. 3;

example 4

(1) Taking 0.12g of graphene oxide in 20mL of distilled water, and carrying out ultrasonic treatment for 2h to form a uniform suspension; then 0.3g of ammonium molybdate and 1.8g of thiourea are added, and the mixture is magnetically stirred for 30min to form a stable mixed solution; then transferring the mixed solution into a reaction kettle, and reacting at 180 ℃ for 24 hours to obtain the composite graphene aerogel; and then placing the aerogel in a freeze dryer, setting the temperature to be-10 ℃, and freeze-drying for 48 hours to obtain the graphene aerogel carrier.

(2) Adding a proper amount of octadecanoic acid (the mass ratio of the octadecanoic acid to the graphene carrier is 20: 1) into the carrier in the step (1), and placing the carrier in a vacuum oven, wherein the vacuum degree is-0.1 MPa, and the temperature is 80 ℃ for soaking for 2 hours. And removing redundant paraffin on the surface to finally obtain the graphene-based multi-response sizing composite phase change material.

The graphene-based multiple-response shaped composite phase change material is a black block, wherein the stearic acid accounts for about 90% by weight, and the loading amount is high; the leakage is avoided in the heating process, and the shaping effect is good; after 100 heating and cooling cycles (heating to 80 ℃, cooling to 0 ℃, and circulating the cycles), the phase change performance is almost unchanged, the cycle performance is good, the absorbance is 1.0-1.8, and the light absorption capacity is strong; and the composite material may be electrically conductive; the material can convert light and electric energy into heat energy for storage.