Flexible shaped composite phase change material and preparation method thereof

Abstract

The invention discloses a flexible shaped composite phase change material and a preparation method thereof, and belongs to the technical field of composite phase change energy storage. The problems that a common flexible shape-stabilized phase-change material needs to be prepared through high-temperature heating and melting, and the loading capacity of a flexible shape-stabilized phase-change material based on a liquid high-molecular polymer is low are solved. The solid-liquid phase change material comprises the following raw material components in parts by weight: 10-65 parts of a solid-liquid phase change material and 35-90 parts of a liquid high polymer material, and the liquid high polymer material comprises a liquid high polymer material body and a curing agent of the liquid high polymer material body. The flexible shape-stabilized phase-change material prepared by the invention is based on a preparation method of a solid phase-change material at normal temperature, and a liquid polymer material is used as a support material of a composite phase-change material. According to the preparation method, the flexible shape-stabilized phase change material can be obtained by dispersing the phase change material powder into the polymer matrix at normal temperature and curing, the loading capacity of the PCM is greatly improved, and the prepared composite material has the properties of high elasticity, high enthalpy value and no leakage.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite phase change energy storage, and particularly relates to a flexible shaped composite phase change material and a preparation method thereof. Background Art

[0002] With the rapid economic development and continuous improvement of the productivity level, the human demand for energy has been increasing day by day. The unreasonable utilization and waste of energy have led to the shortage of traditional fossil energy. Coupled with the low energy utilization efficiency in the process of energy utilization, it has further aggravated the energy consumption and environmental pollution. Therefore, finding renewable energy and improving the energy utilization efficiency have become crucial issues faced by mankind. Thermal energy storage can achieve energy demand balance and multi-time and multi-space heat supply, improve the heat utilization efficiency of the energy system and relieve the energy crisis, so it is considered as a key technology for future energy supply. Among them, latent heat energy storage based on solid-liquid phase change materials stores and releases a large amount of thermal energy reversibly through reverse phase transformation. The charging / discharging process is approximately isothermal and easy to control, so it has the most practical application prospects. However, the leakage problem during the phase change process hinders its practical application.

[0003] Encapsulating the phase change material is one of the effective measures to solve the leakage during the phase change process. At present, most of the encapsulated phase change materials are prepared by heating the phase change material to melt it into a liquid state and melt-blending it with the supporting material. This method requires good compatibility between the phase change material and the polymer material. In recent years, liquid polymer materials have become an ideal choice for encapsulating phase change materials due to their excellent fluidity and processability. Combining liquid polymer materials with phase change materials can not only achieve good encapsulation effects, but also utilize the flexibility and stability of liquid polymer materials to further improve the performance and application range of phase change materials. However, in the currently studied (Yingli Shi, Min Hu, Yufeng Xing and Yuhang Li, Temperature-dependent thermal and mechanical properties of flexible functional PDMS / paraffin composites. 2019, 185: 108219.) flexible shaped composite phase change materials prepared by melt-blending, the paraffin content is only 30wt%. When the paraffin content exceeds 30wt%, even after long-term stirring and mixing, the paraffin cannot be well compatible with polydimethylsiloxane, resulting in the prepared material not being a uniform composite phase change material. Summary of the Invention

[0004] In view of the problems in the prior art that for the shaped composite phase change material based on liquid polymer, heating and melting the phase change material are often required in the preparation process, and it is also limited by the compatibility between the polymer and the phase change material, which not only restricts the possibility of its large-scale production, but also leads to the problem of low loading of the prepared composite phase change material, the present invention provides a flexible shaped composite phase change material and its preparation method.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A flexible shaped composite phase change material, calculated by weight, the raw material components include: 10-65 parts of solid-liquid phase change powder material and 35-90 parts of liquid polymer, and the liquid polymer includes a liquid polymer body and its curing agent.

[0007] After adopting this technical solution, the solid powder is mixed with the liquid support material, and the polymer material is cured at room temperature to form an encapsulation of the phase change material. There is no need to consider the compatibility between the phase change material and the liquid polymer. Therefore, the addition amount of the solid-liquid phase change powder material can reach 65 parts.

[0008] Preferably, the solid-liquid phase change powder material is an alkane, an alcohol or an acid.

[0009] Preferably, the solid-liquid phase change powder material is at least one of tetradecanol, hexadecanol, octadecanol, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, octadecane, eicosane, paraffin, stearic acid, polyethylene glycol.

[0010] Preferably, the liquid polymer body is one of polydimethylsiloxane, epoxy resin, modified epoxy resin, polyurethane resin.

[0011] Preferably, the particle size of the solid-liquid phase change powder material is less than 150 μm.

[0012] Preferably, it includes the following steps:

[0013] Step A: Mix the solid-liquid phase change powder material with a qualified particle size with the liquid polymer body to obtain a suspension;

[0014] Step B: Add the curing agent corresponding to the used liquid polymer to the suspension obtained in Step A;

[0015] Step C: Put the material obtained in Step B into an incubator to induce cross-linking, and the flexible shaped composite phase change material can be obtained after complete curing.

[0016] Preferably, in Step A and Step B, the materials are mixed evenly by stirring, the stirring speed is 300-500 r / min, and the stirring duration is 20-40 min.

[0017] Preferably, step B is crosslinked and cured at room temperature.

[0018] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0019] The flexible shaped phase change material prepared by the present invention is based on a preparation method of a solid phase change material at room temperature, and a liquid polymer is used as a support material for the phase change composite material. At room temperature, by dispersing the phase change material powder into the polymer matrix, the flexible shaped phase change material can be obtained after the matrix is cured. Moreover, this preparation method greatly improves the loading amount of the phase change material, and the prepared shaped phase change material has the properties of high elasticity, high enthalpy value and no leakage. Description of the Drawings

[0020] Figure 1 It is a flowchart of the preparation of a flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention.

[0021] Figure 2 It is a micrograph of the phase change material powder used for the flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention.

[0022] Figure 3 It is a DSC curve graph of the flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention.

[0023] Figure 4 It is a tensile schematic diagram of Example 5 of the flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention.

[0024] Figure 5 It is a flexibility test graph of Example 5 of the flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention.

[0025] Figure 6 It is a thermal stability test graph of the flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention at 70°C.

[0026] Figure 7 It is a sample graph of Example 6 of the flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention.

[0027] Figure 8 It is a sample graph of Example 7 of the flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention.

[0028] Figure 9 It is a sample graph of Example 8 of the flexible shaped composite phase change material based on a solid phase change material at room temperature according to the present invention.

[0029] Figure 10 Sample diagram of Example 9 of a flexible shaped composite phase change material prepared from a solid state phase change material at room temperature according to the present invention.

[0030] Figure 11 Sample diagram of Comparative Example 1 of a flexible shaped composite phase change material prepared from a solid state phase change material at room temperature according to the present invention.

[0031] Figure 12 Sample comparison between Comparative Example 2 and Example 5 of a flexible shaped composite phase change material prepared from a solid state phase change material at room temperature according to the present invention. Detailed implementation manners

[0032] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are only some of the embodiments of the present application, rather than all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0033] Example 1:

[0034] As Figure 1 shown, a flexible shaped composite phase change material based on a solid state phase change material as the matrix and its preparation method:

[0035] 1) At room temperature, grind paraffin particles into fine powder and sieve the paraffin powder using a 120-mesh sieve and a 150-mesh sieve to obtain paraffin powder with a particle size of about 100 - 120 μm;

[0036] 2) Mix 0.24 g of paraffin powder with 2 g of the bulk of polydimethylsiloxane (PDMS) at room temperature and stir magnetically at 500 r / min for 30 min;

[0037] 3) Add 0.2 g of the curing agent of polydimethylsiloxane to the above suspension and stir magnetically at 500 r / min for 30 min;

[0038] 4) Place the above suspension in a constant temperature oven at 25 °C at room temperature to induce cross-linking for 24 h. After the polydimethylsiloxane is completely cured, a flexible shaped composite phase change material with a paraffin content of 10% can be obtained.

[0039] Example 2:

[0040] A flexible shaped composite phase change material based on a solid state phase change material as the matrix and its preparation method:

[0041] 1) At room temperature, grind paraffin particles into fine powder and sieve the paraffin powder using a 120-mesh sieve and a 150-mesh sieve to obtain paraffin powder with a particle size of about 100 - 120 μm;

[0042] 2) Mix 0.55 g of paraffin powder with 2 g of the bulk of polydimethylsiloxane (PDMS) at room temperature and stir magnetically at 500 r / min for 30 min;

[0043] 3) Add 0.2 g of the curing agent for polydimethylsiloxane to the above suspension and stir magnetically at 500 r / min for 30 min;

[0044] 4) Place the above suspension in a constant temperature oven at 25 °C at room temperature to induce crosslinking for 24 h. After the polydimethylsiloxane is completely cured, a flexible shaped composite phase change material with a paraffin content of 20% can be obtained.

[0045] Example 3:

[0046] A flexible shaped composite phase change material based on a solid state phase change material as the matrix and its preparation method:

[0047] 1) At room temperature, grind paraffin particles into fine powder and sieve the paraffin powder using a 120-mesh sieve and a 150-mesh sieve to obtain paraffin powder with a particle size of about 100 - 120 μm; 2) Mix 0.94 g of paraffin powder with 2 g of the bulk of polydimethylsiloxane (PDMS) at room temperature and stir magnetically at 500 r / min for 30 min;

[0048] 3) Add 0.2 g of the curing agent for polydimethylsiloxane to the above suspension and stir magnetically at 500 r / min for 30 min;

[0049] 4) Place the above suspension in a constant temperature oven at 25 °C at room temperature to induce crosslinking for 24 h. After the polydimethylsiloxane is completely cured, a flexible shaped composite phase change material with a paraffin content of 30% can be obtained.

[0050] Example 4:

[0051] A flexible shaped composite phase change material based on a solid state phase change material as the matrix and its preparation method:

[0052] 1) At room temperature, grind paraffin particles into fine powder and sieve the paraffin powder using a 120-mesh sieve and a 150-mesh sieve to obtain paraffin powder with a particle size of about 100 - 120 μm; 2) Mix 1.47 g of paraffin powder with 2 g of the bulk of polydimethylsiloxane (PDMS) at room temperature and stir magnetically at 500 r / min for 30 min;

[0053] 3) Add 0.2 g of the curing agent for polydimethylsiloxane to the above-mentioned suspension, and stir magnetically at 500 r / min for 30 min;

[0054] 4) Place the above-mentioned suspension in a constant temperature oven at room temperature of 25 °C to induce cross-linking for 24 h. After the polydimethylsiloxane is completely cured, a flexible shaped composite phase change material with a paraffin content of 40% can be obtained.

[0055] Example 5:

[0056] A flexible shaped composite phase change material based on a solid phase change material as the matrix and its preparation method:

[0057] 1) Grind paraffin particles into fine powder at room temperature and screen the paraffin powder using a 120-mesh sieve and a 150-mesh sieve to obtain paraffin powder with a particle size of about 100 - 120 μm; 2) Mix 2.2 g of paraffin powder with 2 g of the main body of polydimethylsiloxane (PDMS) at room temperature, and stir magnetically at 500 r / min for 30 min;

[0058] 3) Add 0.2 g of the curing agent for polydimethylsiloxane to the above-mentioned suspension, and stir magnetically at 500 r / min for 30 min;

[0059] 4) Place the above-mentioned suspension in a constant temperature oven at room temperature of 25 °C to induce cross-linking for 24 h. After the polydimethylsiloxane is completely cured, a flexible shaped composite phase change material with a paraffin content of 50% can be obtained.

[0060] Example 6:

[0061] A flexible shaped composite phase change material based on a solid phase change material as the matrix and its preparation method:

[0062] 1) Grind paraffin particles into fine powder at room temperature and screen the paraffin powder using a 120-mesh sieve and a 150-mesh sieve to obtain paraffin powder with a particle size of about 100 - 120 μm; 2) Mix 4.08 g of paraffin powder with 2 g of the main body of polydimethylsiloxane (PDMS) at room temperature, and stir magnetically at 500 r / min for 30 min;

[0063] 3) Add 0.2 g of the curing agent for polydimethylsiloxane to the above-mentioned suspension, and stir magnetically at 500 r / min for 30 min;

[0064] 4) Place the above-mentioned suspension in a constant temperature oven at room temperature of 25 °C to induce cross-linking for 24 h. After the polydimethylsiloxane is completely cured, a flexible shaped composite phase change material with a paraffin content of 50% can be obtained.

[0065] Example 7:

[0066] A flexible shaped composite phase change material based on a solid-state phase change material as the matrix and its preparation method:

[0067] 1) At room temperature, grind paraffin particles into fine powder and screen the paraffin powder using a 120-mesh sieve and a 150-mesh sieve to obtain paraffin powder with a particle size of about 100 - 120 μm; 2) Mix 2.2 g of the paraffin powder with 1.1 g of the epoxy resin body at room temperature and stir magnetically at 500 r / min for 30 min;

[0068] 3) Add 1.1 g of the epoxy resin curing agent to the above suspension and stir magnetically at 500 r / min for 30 min;

[0069] 4) Place the above suspension in a constant temperature oven at 25 °C for 24 h to cure. After the epoxy resin is completely cured, a flexible shaped composite phase change material with a paraffin content of 50% can be obtained.

[0070] Example 8:

[0071] A flexible shaped composite phase change material based on a solid-state phase change material as the matrix and its preparation method:

[0072] 1) At room temperature, grind stearic acid particles into fine powder and screen the stearic acid powder using a 120-mesh sieve and a 150-mesh sieve to obtain stearic acid powder with a particle size of about 100 - 120 μm; 2) Mix 2.2 g of the stearic acid powder with 2 g of the polydimethylsiloxane body at room temperature and stir magnetically at 500 r / min for 30 min;

[0073] 3) Add 0.2 g of the polydimethylsiloxane curing agent to the above suspension and stir magnetically at 500 r / min for 30 min;

[0074] 4) Place the above suspension in a constant temperature oven at 25 °C for 24 h to induce cross-linking. After the epoxy resin is completely cured, a flexible shaped composite phase change material with a paraffin content of 50% can be obtained.

[0075] Example 9:

[0076] A flexible shaped composite phase change material based on a solid-state phase change material as the matrix and its preparation method:

[0077] 1) At room temperature, grind polyethylene glycol particles into fine powder and screen the polyethylene glycol powder using a 120-mesh sieve and a 150-mesh sieve to obtain polyethylene glycol powder with a particle size of about 100 - 120 μm; 2) Mix 2.2 g of the polyethylene glycol powder with 2 g of the polydimethylsiloxane body at room temperature and stir magnetically at 500 r / min for 30 min;

[0078] 3) Add 0.2 g of the curing agent for polydimethylsiloxane to the above suspension, and stir magnetically at 500 r / min for 30 min;

[0079] 4) Place the above suspension in a constant temperature oven at 25 °C at room temperature to induce cross-linking for 24 h. After the epoxy resin is completely cured, a flexible shaped composite phase change material with a paraffin content of 50% can be obtained.

[0080] Comparative Example 1:

[0081] 1) Weigh 4.4 g of block paraffin No. 42 and put it into a beaker, and place the beaker in a water bath at 60 °C to heat.

[0082] 2) After the paraffin is completely melted, add 4 g of polydimethylsiloxane (PDMS) bulk and 0.4 g of the curing agent to the beaker, and stir magnetically for 30 min.

[0083] 3) After stirring evenly, place the obtained emulsion in a constant temperature oven at 60 °C to cross-link and cure the polydimethylsiloxane for 12 h.

[0084] Comparative Example 2:

[0085] 1) Grind paraffin particles into fine powders at room temperature and screen the paraffin powders using a 45-mesh sieve and an 80-mesh sieve to obtain paraffin particles between 45 and 80 meshes, that is, particles with a particle size of about 180 - 380 μm;

[0086] 2) Mix 2.2 g of paraffin particles with 2 g of polydimethylsiloxane (PDMS) bulk at room temperature, and stir magnetically at 500 r / min for 30 min;

[0087] 3) Add 0.2 g of the curing agent for polydimethylsiloxane to the above suspension, and stir magnetically at 500 r / min for 30 min;

[0088] 4) Place the above suspension in a constant temperature oven at 25 °C at room temperature to induce cross-linking for 24 h. After the polydimethylsiloxane is completely cured, a flexible shaped composite phase change material with a paraffin content of 50% can be obtained.

[0089] The parameter changes of Examples 1 - 9 and Comparative Examples 1 - 2 are shown in Table 1 below:

[0090] Table 1

[0091]

[0092]

[0093] The micrographs of the phase change material powders used in Examples 1 - 7 of the present invention are as Figure 2As shown, the particles are mainly spherical-like, which makes the dispersion effect better when the powder particles are mixed with the liquid polymer.

[0094] The DSC curves of the flexible shaped composite phase change materials based on solid state phase change materials obtained in Examples 1-5 of the present invention are as Figure 2 shown. According to the paraffin content of 10%-50%, Examples 1-5 are respectively corresponding. From Figure 3 it can be seen that the phase change enthalpy value of the flexible shaped phase change material increases with the increase of the paraffin content in the composite material, but the phase change temperature and phase change range remain unchanged. The DSC data of Examples 1-5 are shown in Table 2 below:

[0095] Table 2

[0096]

[0097]

[0098] The tensile schematic diagram of the flexible shaped composite phase change material based on solid state phase change materials obtained in Example 5 of the present invention is as Figure 4 shown. It can be seen from the figure that due to the addition of polydimethylsiloxane in the material and the good mechanical properties of polydimethylsiloxane itself, the composite material has good elasticity and toughness.

[0099] The flexibility test diagram of the flexible shaped composite phase change material based on solid state phase change materials obtained in Example 5 of the present invention is as Figure 5 shown. It can be seen that when the material bears a 500g weight, obvious cracks appear on the surface of the composite material. Therefore, the maximum weight that the material can bear is about 500g.

[0100] The thermal stability test diagram of the flexible shaped composite phase change materials based on solid state phase change materials obtained in Examples 1-5 of the present invention at 70°C is as Figure 6 shown. It can be seen from the figure that the flexible shaped phase change material has almost no leakage compared with pure paraffin under the heating condition of 70°C, indicating that the polydimethylsiloxane completely wraps the paraffin particles.

[0101] The sample diagram of the flexible shaped composite phase change material based on solid state phase change materials obtained in Example 6 of the present invention is as Figure 7 shown, in which the added content of paraffin is about 65%, which is also the maximum content of the preparation method of the present invention.

[0102] The sample diagram of the flexible shaped composite phase change material based on solid state phase change materials obtained in Example 7 of the present invention is as Figure 8 shown, in which the added content of paraffin is about 50%, and the liquid polymer used is epoxy resin.

[0103] The sample diagram of the flexible shaped composite phase change material based on the solid-state phase change material obtained in Example 8 of the present invention is as follows Figure 9 shown. The phase change material used is stearic acid, and the addition content is about 50%. The liquid polymer used is polydimethylsiloxane.

[0104] The sample diagram of the flexible shaped composite phase change material based on the solid-state phase change material obtained in Example 9 of the present invention is as follows Figure 10 shown. The phase change material used is polyethylene glycol 6000, and the addition content is about 50%. The liquid polymer used is polydimethylsiloxane.

[0105] The sample diagram of the flexible shaped phase change material obtained in Comparative Example 1 is as follows Figure 11 shown. Comparative Example 1 is a material prepared by a melt blending method, and the paraffin content is about 50%. However, as can be seen from Figure 11 it, a large amount of paraffin is not wrapped by polydimethylsiloxane. This is because the compatibility between liquid paraffin and polydimethylsiloxane is not good. Even after long-term stirring, during the curing process of polydimethylsiloxane, the unwrapped paraffin will leak out.

[0106] The comparative diagram of the samples of the flexible shaped phase change materials obtained in Example 5 of the present invention and Comparative Example 2 is as follows Figure 12 shown. As can be seen from the figure, the sample structure of Example 5 is denser than that of the sample of Comparative Example 2. There are pores of different sizes in the sample of Comparative Example 2. This is because larger particle sizes are difficult to be evenly distributed during mixing, and larger pores will be formed during curing. While small particles can be more evenly distributed during mixing, and the contact area between small particles and the matrix material is larger, the interfacial bonding is stronger, and the structure is more compact.

[0107] The above embodiments only represent the specific implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation to the protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application.

Claims

1. A flexible shaped composite phase change material, characterized in that: The raw material components include, by weight: 10 to 65 parts of solid-liquid phase change powder material and 35 to 90 parts of liquid high molecular polymer, wherein the liquid high molecular polymer includes a liquid high molecular polymer body and a curing agent thereof.

2. The flexible shaped composite phase change material according to claim 1, characterized in that: The solid-liquid phase change powder material is one or more of alkanes, alcohols or acids.

3. The flexible shaped composite phase change material according to claim 2, characterized in that: The solid-liquid phase change powder material is at least one of tetradecanol, hexadecanol, octadecyl alcohol, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, octadecane, eicosane, paraffin, stearic acid, and polyethylene glycol.

4. The flexible shaped composite phase change material according to claim 1, characterized in that: The liquid high molecular polymer body is one of polydimethylsiloxane, epoxy resin, modified epoxy resin and polyurethane resin.

5. A flexible shaped composite phase change material according to any one of claims 1 to 4, characterized in that: The particle size of the solid-liquid phase change powder material is less than 150 μm.

6. A method for preparing the flexible shaped composite phase change material according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step A: mixing a solid-liquid phase change powder material with a particle size that meets the requirements with a liquid polymer body to obtain a suspension; Step B: adding a curing agent corresponding to the liquid polymer to the suspension obtained in step A; Step C: placing the material obtained in step B into a constant temperature box to induce cross-linking, and obtaining a flexible shaped composite phase change material after complete solidification.

7. The method for preparing a flexible shaped composite phase change material according to claim 6, characterized in that: In step A and step B, the materials are mixed uniformly by stirring, the stirring speed is 300-500 r / min, and the stirring time is 20-40 min.

8. The method for preparing a flexible shaped composite phase change material according to claim 6, characterized in that: Step B is cross-linked and cured at room temperature.

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