Aerogel composite materials and their preparation methods, thermal insulation and energy storage materials

Abstract

This invention provides an aerogel composite material and its preparation method, as well as a thermal insulation and energy storage material. The aerogel composite material has a porous framework structure, which includes phase change material particles and a polymer. The polymer coats at least a portion of the surface of the phase change material particles. The phase change enthalpy of the aerogel composite material is not less than 200 J / g, and the thermal conductivity is not higher than 0.16 W / (m·K). This invention obtains an aerogel composite material by assembling phase change material particles and polymer together to form an aerogel framework structure. Its matrix is ​​composed of phase change material particles and a polymer network, exhibiting excellent thermal insulation performance. At the same time, the phase change material, as a functional phase, provides phase change thermal storage capacity. The synergistic effect of the phase change material and the polymer not only constructs a stable framework structure but also improves the low thermal conductivity and high energy storage density of the aerogel composite material, meeting the dual requirements of efficient thermal insulation and energy storage in practical applications.

Description

Technical Field

[0001] This invention belongs to the field of phase change aerogel composite material technology, specifically relating to an aerogel composite material and its preparation method, as well as a thermal insulation and energy storage material. Background Technology

[0002] The building thermal management industry is a key sector that has experienced rapid growth in recent years. As people's demand for high-quality, comfortable, and energy-efficient living environments continues to increase, the market demand for building energy conservation and thermal management is also growing.

[0003] Aerogel is a traditional building insulation material with advantages such as lightweight and heat insulation. However, it is brittle, easily broken, has poor mechanical load-bearing capacity, and its heat storage performance needs to be improved. It also has poor stability in high-intensity and long-term applications. Therefore, it is only suitable for heat insulation applications in specific environments.

[0004] Therefore, in response to the actual engineering needs in the field of building constant temperature thermal management, there is an urgent need to develop new types of thermal insulation and energy storage materials. Summary of the Invention

[0005] This invention provides aerogel composite materials and their preparation methods, as well as thermal insulation and energy storage materials, which address the problems of high thermal conductivity, low energy storage density, and low stability in high-strength, long-cycle applications of existing aerogel materials.

[0006] In a first aspect, the present invention provides an aerogel composite material having a porous framework structure, the porous framework structure comprising phase change material particles and a polymer, the polymer coating at least a portion of the surface of the phase change material particles;

[0007] The phase transition enthalpy of the aerogel composite material is not less than 200 J / g, and the thermal conductivity is not higher than 0.16 W / (m·K).

[0008] Compared with the prior art, the advantages of the present invention are as follows: by assembling phase change material particles and polymers together to form an aerogel skeleton structure, an aerogel composite material is obtained. Its matrix is ​​composed of phase change material particles and polymer network, which has excellent thermal insulation performance. At the same time, the phase change material, as a functional phase, provides phase change heat storage capacity. The synergistic effect of phase change material and polymer not only constructs a stable skeleton structure, but also improves the low thermal conductivity and high energy storage density of the aerogel composite material, meeting the dual requirements of efficient thermal insulation and energy storage in practical applications.

[0009] Furthermore, the mass ratio of the phase change material particles to the polymer is (1~9):(0.3~1.5).

[0010] Furthermore, the particle size of the phase change material is 2~50 μm; and / or,

[0011] The solid content of the phase change material particles is 80-90%.

[0012] Furthermore, the phase change material particles include at least one of stearic acid, lauryl alcohol, paraffin, and methyl palmitate; and / or,

[0013] The polymer includes at least one of gelatin, chitosan, polyacrylamide, polyvinyl alcohol, and sodium alginate.

[0014] Further, the phase change material particles are paraffin wax, the polymer is polyvinyl alcohol, and the mass ratio of the paraffin wax to the polyvinyl alcohol is (0.4~0.8):(5~7); and / or,

[0015] The phase change material particles are paraffin wax, and the polymer comprises polyacrylamide and polyvinyl alcohol in a mass ratio of (2~4):(0.5~1.5).

[0016] The phase change material particles comprise paraffin and stearic acid in a mass ratio of (3~5):(1~3), and the polymer comprises gelatin and polyvinyl alcohol in a mass ratio of (2~4):(0.5~1.5).

[0017] In a second aspect, the present invention provides a method for preparing an aerogel composite material, used to prepare the aerogel composite material described in the first aspect, characterized by comprising the following steps:

[0018] (1) The molten phase change material is added to the polymer solution, and the mixture is subjected to stirring pre-dispersion treatment and ultrasonic pulverization treatment in sequence. After cooling, a phase change material particle emulsion is obtained.

[0019] (2) The phase change material particle emulsion is poured into a mold and subjected to freeze-thaw cycle treatment, and then freeze-dried to obtain the aerogel composite material; wherein the freeze-thaw cycle treatment includes freezing treatment and thawing treatment performed sequentially.

[0020] Furthermore, the freezing treatment temperature is -5 to -40°C, and the duration is 6 to 48 hours; and / or,

[0021] The thawing process is carried out at room temperature for 6 to 48 hours; the freeze-thaw cycle is repeated 1 to 8 times.

[0022] Furthermore, the temperature of the stirring pre-dispersion treatment is 20~90℃, and the time is 1~60min; and / or,

[0023] The ultrasonic fragmentation treatment is performed at a temperature of 20~90℃ for a time of 1~30 min; and / or,

[0024] The freeze-drying process is carried out at a temperature of -60 to -85°C for 6 to 72 hours.

[0025] Furthermore, the freeze-drying process includes a pre-cooling treatment, wherein the temperature of the pre-cooling treatment is -10 to -80°C and the time is 10 min to 5 h.

[0026] Thirdly, the present invention provides a thermal insulation and energy storage material, including the aerogel composite material described in the first aspect or the aerogel composite material prepared by the preparation method of the aerogel composite material described in the second aspect. Attached Figure Description

[0027] Figure 1 These are the reliability verification results from the test examples of this invention;

[0028] Figure 2 This is a SEM image of the aerogel composite material prepared in Example 4 of the present invention;

[0029] Figure 3 This is a SEM image of the aerogel composite material prepared in Example 4 of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0031] In a first aspect, the present invention provides an aerogel composite material having a porous framework structure, the porous framework structure comprising phase change material particles and a polymer, wherein the polymer coats at least a portion of the surface of the phase change material particles.

[0032] The phase transition enthalpy of the aerogel composite material is not less than 200 J / g, and the thermal conductivity is not higher than 0.16 W / (m·K).

[0033] The aerogel composite material provided by this invention comprises a skeletal structure formed by the assembly of phase change material particles and polymers. The polymer forms a coating layer on the surface of the phase change material particles, and the phase change material particles and their polymer coating layer form a microsphere structure. The microspheres adsorb through electrostatic effects to form a porous skeletal structure, exhibiting excellent thermal insulation performance. Simultaneously, the phase change material, as a functional phase, provides phase change heat storage capacity. The porous structure endows the aerogel with excellent thermal insulation properties, while the phase change material achieves its heat storage function by absorbing and releasing latent heat when the temperature changes. The polymer coating layer prevents the phase change material from flowing or leaking, thus enabling the material to maintain structural stability while possessing efficient thermal insulation and heat storage capabilities.

[0034] The aerogel composite material provided by this invention is formed by assembling phase change material particles and polymers to form an aerogel skeleton structure. The matrix of the aerogel composite material is composed of phase change material particles and polymer network, which has excellent thermal insulation performance. At the same time, the phase change material, as a functional phase, provides phase change heat storage capacity. The synergistic effect of phase change material and polymer not only constructs a stable skeleton structure, but also improves the low thermal conductivity and high energy storage density of the aerogel composite material, meeting the dual requirements of efficient thermal insulation and energy storage in practical applications.

[0035] Furthermore, the mass ratio of phase change material particles to polymer is (1~9):(0.3~1.5).

[0036] By further limiting the mass ratio of phase change material particles to polymers, the synergistic effect can be further enhanced, the thermal conductivity of aerogel composites can be further reduced, the energy storage density can be increased, and the stability of aerogel composites can be further improved.

[0037] Specifically, the particle size of the phase change material particles is 2~50μm; the solid content of the phase change material particles is 80~90%.

[0038] By further defining the phase change material particles and polymers, the synergistic effect can be further enhanced, the thermal conductivity of the aerogel composite material can be further reduced, the energy storage density can be increased, and the stability of the aerogel composite material can be further improved.

[0039] Optionally, the phase change material particles include at least one of stearic acid, lauryl alcohol, paraffin and methyl palmitate; the polymer includes at least one of gelatin, chitosan, polyacrylamide, polyvinyl alcohol and sodium alginate.

[0040] When the phase change material particles or polymers selected from the above-mentioned limited materials are used, the synergistic effect can be further enhanced, the thermal conductivity of the aerogel composite material can be further reduced, the energy storage density can be increased, and the stability of the aerogel composite material can be further improved.

[0041] In one specific embodiment, the phase change material particles are paraffin wax, the polymer is polyvinyl alcohol, and the mass ratio of paraffin wax to polyvinyl alcohol is (5~7):(0.4~0.8).

[0042] In another specific embodiment, the phase change material particles are paraffin wax; the polymer is polyacrylamide and polyvinyl alcohol in a mass ratio of (2~4):(0.5~1.5).

[0043] In another specific embodiment, the phase change material particles are paraffin wax and stearic acid in a mass ratio of (3~5):(1~3); the polymer is gelatin and polyvinyl alcohol in a mass ratio of (2~4):(0.5~1.5).

[0044] The inventors discovered that when the phase change material particles and polymers are combined as described above, and through a special ratio, the thermal conductivity of the aerogel composite material can be further reduced, the energy storage density can be increased, and the stability of the aerogel composite material can be further improved.

[0045] In a second aspect, the present invention provides a method for preparing an aerogel composite material, used to prepare the aerogel composite material of the first aspect, comprising the following steps:

[0046] (1) The molten phase change material is added to the polymer solution, and the mixture is subjected to stirring pre-dispersion treatment and ultrasonic pulverization treatment in sequence. After cooling, a phase change material particle emulsion is obtained.

[0047] (2) After the phase change material particle emulsion is poured into the mold, it is subjected to freeze-thaw cycle treatment and then freeze-drying treatment to obtain aerogel composite material; wherein, the freeze-thaw cycle treatment includes freezing treatment and melting treatment performed sequentially.

[0048] In step (1), molten phase change material particles are added to a completely dissolved, homogeneous, and transparent polymer solution. After stirring and pre-dispersing treatment and ultrasonic pulverization treatment, the polymer is coated on the surface of the phase change material particles. After cooling, a stable phase change material particle emulsion is obtained. In step (2), the phase change material particle emulsion is poured into a mold and subjected to freeze-thaw cycle treatment, followed by freeze-drying treatment to form an aerogel composite material with a porous skeleton structure.

[0049] The method for preparing aerogel composite materials provided by the present invention involves freeze-thaw cycles of a stable, dispersed emulsion of polymer-coated phase change material particles, followed by freeze-drying. This process forms an excellent porous framework structure, creating a good interface between the polymer-coated phase change material microspheres. The method can produce aerogel composite materials with a phase change enthalpy of not less than 200 J / g and a thermal conductivity of not more than 0.16 W / (m·K), and exhibits good stability.

[0050] In one specific embodiment, the molten phase change material particles are obtained by melting in a constant temperature oven at 50°C.

[0051] In one specific embodiment, the concentration of the polymer solution is 40~80 g / L.

[0052] Furthermore, the freezing treatment temperature is -5 to -40°C, and the duration is 6 to 48 hours; the thawing treatment is carried out at room temperature for 6 to 48 hours; the number of freeze-thaw cycles is 1 to 8.

[0053] It is understood that freeze-thaw cycle treatment includes sequential freezing and thawing treatments. Further limiting the parameters of freezing and thawing treatments and the number of cycles can further give aerogel composites excellent structure, further reduce the thermal conductivity of aerogel composites, increase energy storage density, and further improve the stability of aerogel composites.

[0054] Optionally, the temperature for the stirring and pre-dispersion treatment is 20~90℃, and the time is 1~60min;

[0055] The ultrasonic crushing treatment temperature is 20~90℃, and the time is 1~30min;

[0056] The freeze-drying process is carried out at a temperature of -60 to -85°C for 6 to 72 hours.

[0057] In one specific embodiment, the freeze-drying process further includes a pre-cooling process, wherein the temperature of the pre-cooling process is -10 to -80°C and the time is 10 min to 5 h.

[0058] Pre-cooling treatment can further enhance the effects of freeze-drying, further improve the structure of aerogel composites, further reduce the thermal conductivity of aerogel composites, increase energy storage density, and further improve the stability of aerogel composites.

[0059] Thirdly, the present invention provides a thermal insulation and energy storage material, including an aerogel composite material prepared by the method of the first aspect or the method of the second aspect.

[0060] The thermal insulation and energy storage material provided by this invention has a low thermal conductivity, high energy storage density, and high stability in high-intensity and long-cycle applications, providing a new solution for the development of constant-temperature thermal management in the field of thermal management.

[0061] The following detailed description of an aerogel composite material provided by the present invention is provided through specific embodiments. Example 1

[0062] (1) Under magnetic stirring conditions, a certain amount of polymer (gelatin) is heated and stirred until completely dissolved to obtain a homogeneous and transparent polymer solution;

[0063] (2) The phase change material (paraffin) is placed in a 50°C constant temperature oven for melting to obtain molten phase change material particles;

[0064] (3) Take a 25ml beaker, add the polymer solution, and then add the molten phase change material particles to the beaker; wherein the mass ratio of the phase change material particles to the polymer is 7:0.4; then, the mixture of phase change material and polymer solution is heated in a 50℃ water bath and stirred for 5min for pre-dispersion, then transferred to an ultrasonic cell disruptor for 5min for cell disruption, and obtained a phase change material particle emulsion after cooling;

[0065] (4) Pour the cooled paraffin emulsion into the mold, seal it with an acrylic cover and place it in a plastic bag; freeze it at -20℃ for 12 hours and thaw it at room temperature for 12 hours, which is one freeze-thaw cycle; repeat the freeze-thaw cycle 3 times.

[0066] (5) The sample after the freeze-thaw cycle was pre-frozen at -50~-80℃ for 60 min, and then transferred to a freeze dryer for freeze drying for 24 h to obtain the aerogel composite material. Example 2

[0067] The difference between this embodiment and Embodiment 1 is that the polymer is replaced with chitosan. Example 3

[0068] The difference between this embodiment and Embodiment 1 is that the polymer is replaced with polyacrylamide. Example 4

[0069] The difference between this embodiment and Embodiment 1 is that the polymer is replaced with polyvinyl alcohol. Example 5

[0070] The difference between this embodiment and Embodiment 1 is that the polymer is replaced with sodium alginate. Example 6

[0071] The difference between this embodiment and Embodiment 1 is that the polymer includes polyacrylamide and polyvinyl alcohol in a mass ratio of 3:1. Example 7

[0072] The difference between this embodiment and Embodiment 1 is that the phase change material includes paraffin and stearic acid in a mass ratio of 3:1, and the polymer includes gelatin and polyvinyl alcohol in a mass ratio of 5:1. Example 8

[0073] The difference between this embodiment and embodiment 1 is that in step (4), the freeze-thaw cycle is repeated 5 times. Example 9

[0074] The difference between this embodiment and embodiment 1 is that in step (4), the freeze-thaw cycle is repeated 8 times. Example 10

[0075] The difference between this embodiment and Embodiment 1 is that the phase change material is replaced with lauryl alcohol.

[0076] Comparative Example 1

[0077] The difference between this comparative example and Example 1 is that step (4) is not performed.

[0078] Experimental Example 1

[0079] Thermal performance characterization, reliability verification, and high and low temperature cycling stability testing were performed on each of the above embodiments and comparative examples.

[0080] Thermal performance was characterized using a Q20 differential scanning gauging instrument purchased from TA Instruments, USA, to obtain the phase transition enthalpy of the samples. Tests were conducted under a nitrogen atmosphere, with a temperature range of 20–100 °C and a heating rate of 10 °C / min. Thermal conductivity was measured using a TPS2500S thermal conductivity meter, employing the Hot-disk method according to ISO 22007-2 standards, at 30 °C. Three parallel tests were performed at each temperature point, with an air atmosphere.

[0081] The reliability verification method includes the following steps: Paraffin and phase change aerogel samples are placed in a 50℃ oven and heated continuously for 6 hours. During the heating process, filter paper is placed at the bottom of the sample to absorb any leaked paraffin. The weight of the samples is measured before and after heating, and the condition of the samples is observed.

[0082] The method for high and low temperature cycling stability testing includes the following steps: Aerogel composite materials and paraffin phase change materials are placed in a BIO-RAD T100 thermal cycler (USA) for testing. 500 accelerated thermal cycles are performed between 4 and 50°C, with each temperature held for 5 minutes. Samples are taken every 100 cycles. The phase transition enthalpy of the samples after accelerated thermal cycling is measured using a Q20 differential scanning gauging instrument (purchased from TA Instruments, USA). The final phase transition enthalpy value of the samples is obtained. The test is conducted under a nitrogen atmosphere, with a temperature range of 20–100°C and a heating rate of 10°C / min.

[0083] The test results are shown in Table 1. Figure 1 As shown, Figure 1 It can be seen that the aerogel provided by the present invention can still maintain its original appearance under continuous high temperature environment, without the phenomenon of paraffin melting or structural damage.

[0084] Table 1

[0085] Group Phase transition enthalpy (J / g) Thermal conductivity (W / (m·K)) Leakage rate (%) Phase transition enthalpy decay rate (%) after 500 thermal cycles Example 1 204.6 0.1547 0.464 4.57 Example 2 206.1 0.15875 0.349 2.51 Example 3 209.8 0.1375 1.145 3.67 Example 4 209 0.14265 0.443 3.34 Example 5 216.68 0.1188 0.357 5.96 Example 6 211.4 0.11365 0.771 2.83 Example 7 226.2 0.1055 0.306 4.78 Example 8 200.62 0.1222 0.54 2.74 Example 9 213.7 0.1428 0.38 3.86 Example 10 203.1 0.15425 0.48 7.21 Comparative Example 1 185.4 0.21 85.6 90 paraffin 237.9 0.25 - -

[0086] As shown in Table 1, the phase change enthalpy of the aerogel composite materials provided by this invention is greater than 200 J / g, and the thermal conductivity is less than 0.16 W / (m·K), with the highest enthalpy reaching 226 J / g and the lowest thermal conductivity being 0.105 W / (m·K). Furthermore, the phase change material and the polymer together constitute the skeleton structure of the aerogel, and the interfacial bonding is excellent, effectively preventing leakage of the phase change material during the phase change process. The aerogel composite material maintains its original appearance even under sustained high-temperature conditions, without any melting of the phase change material or structural damage. Measurement results show that, except for Example 3, the leakage rate of the other samples is less than 1%. This fully demonstrates the excellent reliability of the composite material and effectively overcomes the problem of leakage that easily occurs in traditional phase change materials in practical thermal management engineering applications. In addition, the aerogel composite material provided by this invention still maintains high heat storage performance after 500 cycles of alternating high and low temperatures, with a performance decay of about 5%. This fully demonstrates the excellent durability of the material, effectively solves the problem of traditional phase change materials being prone to failure after long-term use, and significantly improves its reliability and long-term stability in practical engineering applications of thermal management.

[0087] Experimental Example 2

[0088] The results of scanning electron microscopy (SEM) of Example 4 are as follows: Figure 2 , Figure 3 As shown.

[0089] from Figure 2 , Figure 3 It can be seen that paraffin and polyvinyl alcohol together constitute the skeleton structure of the aerogel composite material and have a good interfacial bonding state, which can effectively prevent the leakage of paraffin during the phase change process.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should all be considered to be within the protection scope of the present invention.

Claims

1. An aerogel composite material, characterized in that, It has a porous framework structure, the porous framework structure comprising phase change material particles and a polymer, the polymer coating at least a portion of the surface of the phase change material particles; The aerogel composite material has a phase change enthalpy of not less than 200 J / g and a thermal conductivity of not more than 0.16 W / (m·K); the phase change material particles include at least one of stearic acid, lauryl alcohol, paraffin and methyl palmitate; the polymer includes at least one of gelatin, chitosan, polyacrylamide, polyvinyl alcohol and sodium alginate. The preparation method of the aerogel composite material includes the following steps: (1) The molten phase change material is added to the polymer solution, and the mixture is subjected to stirring pre-dispersion treatment and ultrasonic pulverization treatment in sequence. After cooling, a phase change material particle emulsion is obtained. (2) The phase change material particle emulsion is poured into a mold and subjected to freeze-thaw cycle treatment, and then freeze-dried to obtain the aerogel composite material; wherein the freeze-thaw cycle treatment includes freezing treatment and thawing treatment performed sequentially.

2. The aerogel composite material according to claim 1, characterized in that, The mass ratio of the phase change material particles to the polymer is (1~9):(0.3~1.5).

3. The aerogel composite material according to claim 1, characterized in that, The phase change material particles have a particle size of 2~50μm; and / or, The solid content of the phase change material particles is 80-90%.

4. The aerogel composite material according to claim 1, characterized in that, The phase change material particles are paraffin wax, the polymer is polyvinyl alcohol, and the mass ratio of the paraffin wax to the polyvinyl alcohol is (5~7):(0.4~0.8); and / or, The phase change material particles are paraffin wax, and the polymer comprises polyacrylamide and polyvinyl alcohol in a mass ratio of (2~4):(0.5~1.5); and / or, The phase change material particles comprise paraffin and stearic acid in a mass ratio of (3~5):(1~3), and the polymer comprises gelatin and polyvinyl alcohol in a mass ratio of (2~4):(0.5~1.5).

5. A method for preparing an aerogel composite material, used to prepare the aerogel composite material according to any one of claims 1-4, characterized in that, Includes the following steps: (1) The molten phase change material is added to the polymer solution, and the mixture is subjected to stirring pre-dispersion treatment and ultrasonic pulverization treatment in sequence. After cooling, a phase change material particle emulsion is obtained. (2) The phase change material particle emulsion is poured into a mold and subjected to freeze-thaw cycle treatment, and then freeze-dried to obtain the aerogel composite material; wherein the freeze-thaw cycle treatment includes freezing treatment and thawing treatment performed sequentially.

6. The method for preparing the aerogel composite material according to claim 5, characterized in that, The freezing treatment temperature is -5 to -40°C, and the duration is 6 to 48 hours; and / or, The thawing process is carried out at room temperature for 6 to 48 hours; the freeze-thaw cycle is repeated 1 to 8 times.

7. The method for preparing the aerogel composite material according to claim 5 or 6, characterized in that, The stirring and pre-dispersion treatment is carried out at a temperature of 20-90℃ for 1-60 minutes; and / or, The ultrasonic pulverization process is performed at a temperature of 20-90℃ for a time of 1-30 minutes; and / or, The freeze-drying process is carried out at a temperature of -60 to -85°C for 6 to 72 hours.

8. The method for preparing the aerogel composite material according to claim 7, characterized in that, The freeze-drying process also includes a pre-cooling treatment, which is performed at a temperature of -10 to -80°C for 10 minutes to 5 hours.

9. A thermal insulation and energy storage material, characterized in that, The aerogel composite material includes the aerogel composite material according to any one of claims 1-4 or the aerogel composite material prepared by the preparation method according to any one of claims 5-8.

Images