High-stability composite phase change material and preparation method thereof

Abstract

The invention belongs to the technical field of phase change material preparation, and particularly relates to a high-stability composite phase change material and a preparation method thereof. According to the method, an organic solid-liquid phase change material is taken as a solvent, a reaction monomer octadecyl acrylate and a cross-linking agent 1, 6-hexanediol diacrylate are subjected to a cross-linking reaction through a redox initiation system (benzoyl peroxide and N, N-dimethyl-p-toluidine), and the solid-liquid phase change material is prepared. A phase-change high-molecular polymer with a phase-change function is constructed, a coating structure is formed on the organic solid-liquid phase-change material, and finally the composite phase-change material with excellent thermal stability and high latent heat characteristics is prepared. The preparation process disclosed by the invention can be carried out under a low-temperature condition, energy consumption and production cost can be effectively reduced, the process is simple, and batch production is easy; the prepared composite phase change material has wide application prospects in the fields of energy storage, temperature control and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of phase change material preparation, and particularly relates to a high-stability composite phase change material and a preparation method thereof. BACKGROUND

[0002] In the field of modern thermal management technology, phase change materials have become the core materials in key scenarios such as power battery thermal management and electronic device heat dissipation, due to their characteristics of realizing efficient heat storage / heat release through the phase change process. At present, phase change materials are mainly divided into two systems: organic phase change materials and inorganic phase change materials. Inorganic phase change materials are greatly limited in actual engineering applications due to inherent defects such as low thermal decomposition temperature, significant supercooling phenomenon and serious phase separation tendency. In contrast, organic phase change materials have become the mainstream direction of current research and application due to their advantages such as high phase change latent heat, controllable cost and wide raw material sources. Organic phase change materials are further divided into solid-solid phase change materials and solid-liquid phase change materials. Although solid-liquid phase change materials can absorb a large amount of heat during the phase change process due to their high phase change latent heat, they have the problems of poor thermal stability and easy liquid leakage at high temperatures, which leads to a significant decrease in the efficiency of the thermal management system. The existing technology usually uses high-stability materials as a supporting skeleton for composite modification, which can improve the stability but inevitably leads to a significant decrease in the phase change latent heat, making it difficult to meet the dual requirements of high stability and high heat storage capacity. Although solid-solid phase change materials have good thermal stability and anti-leakage capacity, their phase change latent heat is relatively low, and the heat storage efficiency per unit mass or volume is obviously inferior, which limits their application in scenarios with strict requirements for thermal management efficiency. Therefore, developing a composite phase change material with high stability and high latent heat has become a technical problem to be solved in the current thermal management field.

[0003] In view of the above problems, the present application uses a solid-solid phase change material polymer with latent heat characteristics as a supporting skeleton, and combines an organic solid-liquid phase change material as a phase change component to prepare a composite phase change material. The composite phase change material effectively retains the high heat storage performance of the phase change material while ensuring that the material has excellent thermal stability and form retention capacity, significantly improves the applicability and thermal management efficiency of the material in scenarios such as power battery thermal management and electronic device heat dissipation, and provides a new solution for the technical development in the field of phase change materials. SUMMARY

[0004] The present application aims to provide a high-stability composite phase change material and a preparation method thereof.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] The present application provides a high-stability composite phase change material, which comprises an organic solid-liquid phase change material, a phase change polymer and a heat-conducting agent.

[0007] The specific reaction of the phase change high molecular polymer is as follows: the cross-linking reaction of the reaction monomer octadecyl acrylate and the cross-linking agent 1,6-hexanediol diacrylate occurs under the action of the redox initiation system (benzoyl peroxide and N,N-dimethyl-p-toluidine) to form.

[0008] Preferably, the high-stability composite phase change material includes, in terms of mass percentage, 30-45% of the organic solid-liquid phase change material, 55-70% of the phase change high molecular polymer, and 0-6% of the heat-conducting agent.

[0009] Preferably, the molar ratio of octadecyl acrylate: 1,6-hexanediol diacrylate is 40:1.

[0010] Preferably, the amount of benzoyl peroxide is 1% and the amount of N,N-dimethyl-p-toluidine is 0.25% in terms of mass percentage.

[0011] Preferably, the organic solid-liquid phase change material includes at least one of paraffin, polyethylene glycol (PM=1500), polyethylene glycol (PM=2000), myristyl alcohol, cetyl alcohol, stearyl alcohol, myristyl amine, cetyl amine, stearyl amine, myristic acid, palmitic acid, and stearic acid.

[0012] Preferably, the heat-conducting agent includes at least one of expanded graphite, carbon fiber, carbon nanotube, boron nitride, and graphene.

[0013] The application also provides a preparation method of the high-stability composite phase change material.

[0014] Step one: mix the organic solid-liquid phase change material and octadecyl acrylate, melt them in an oil bath, and stir them uniformly using mechanical stirring to obtain a mixture a;

[0015] Step two: add the heat-conducting agent to the mixture a in batches, continue to stir the mixture uniformly using mechanical stirring to obtain a mixture b;

[0016] Step three: lower the temperature of the oil bath, add 1,6-hexanediol diacrylate and benzoyl peroxide to the mixture b, and continue to stir the mixture uniformly using mechanical stirring to obtain a mixture c;

[0017] Step four: add N,N-dimethyl-p-toluidine to the mixture c, stir the mixture uniformly using mechanical stirring, transfer the mixture to an oven for solidification reaction, and obtain the high-stability composite phase change material.

[0018] Preferably, the temperature of the oil bath in step one is 60°C, the mechanical stirring speed is 300-500 rpm, and the stirring time is 20-30 min.

[0019] Preferably, the mechanical stirring speed in step two is 800-1200 rpm, and the stirring time is 45-60 min.

[0020] Preferably, the temperature of the oil bath in step three is lowered to 40℃, the mechanical stirring speed is 800-1200 rpm, and the stirring time is 5-10 min.

[0021] Preferably, the mechanical stirring speed in step four is 800-1200 rpm, and the stirring time is 1-2 min.

[0022] Preferably, the oven temperature in step four is 40℃, and the curing reaction time is 60 min.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) Solving the inherent contradiction between stability and latent heat: through the redox initiation system (benzoyl peroxide and N,N-dimethyl-p-toluidine) to initiate in-situ polymerization of monomers and crosslinking agent at low temperature, the phase change polymer directly coats the organic solid-liquid phase change material, forming a "supporting skeleton @ phase change core material" integrated structure. This design not only avoids the dilution effect of the overall energy storage density of the phase change material caused by the lack of phase change latent heat of the supporting material in the traditional physical blending method, but also improves the thermal stability and form retention ability of the material through chemical crosslinking, realizing the synergistic optimization of high latent heat characteristics and anti-leakage performance.

[0025] (2) Reducing energy consumption and process complexity: Compared with the existing technology which relies on high-temperature melting mixing or solvent-assisted forming process, the present application utilizes the low-temperature reaction characteristics of the redox initiation system (which can react and cure at as low as 40℃), significantly reducing the energy consumption demand in the production process; at the same time, the one-step polymerization coating process eliminates the complicated steps such as drying and molding in the traditional composite method, simplifying the production process and making it easier to realize continuous batch production.

[0026] (3) Expanding the engineering application scenarios of the material: The prepared composite phase change material has both the high latent heat advantage of organic solid-liquid phase change material and the structural stability of high molecular polymer, and can be directly applied to power battery thermal management, electronic equipment heat dissipation and other scenes that have strict requirements on material form stability and heat storage efficiency, overcoming the technical bottleneck of traditional solid-liquid phase change material leakage and solid-solid phase change material latent heat deficiency, providing a new material solution for the miniaturization and high efficiency of thermal management system. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 DSC curve of the high-stability composite phase change material obtained in Example 1;

[0028] Figure 2 DSC curve of the high-stability composite phase change material obtained in Example 1;

[0029] Figure 3 DSC curve of the high-stability composite phase change material obtained in Example 3;

[0030] Figure 4 Mass loss curve of the high-stability composite phase change material obtained in Example 1 heated at 55℃ for 120h;

[0031] Figure 5 Shape change of the high-stability composite phase change material obtained in Example 1 during the change from 30℃ to 250℃. DETAILED DESCRIPTION

[0032] The present application will be further described in conjunction with specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and devices used in the present application are conventional reagents, methods and devices in the technical field.

[0033] Example 1:

[0034] A preparation method of a high-stability composite phase change material, the specific steps are as follows:

[0035] Step one: 60g of paraffin and 122.5g of octadecyl acrylate were placed in an oil bath pot at 60℃ for mixing, and mechanical stirring was carried out at a speed of 300rpm until the solution was uniform, and the stirring time was 20min, to obtain a mixture a;

[0036] Step two: 12g of expanded graphite was slowly added in batches to the mixture a, and mechanical stirring was carried out at a speed of 1000rpm until the mixture was uniform, and the stirring time was 60min, to obtain a mixture b;

[0037] Step three: the temperature of the oil bath pot was adjusted to 40℃, and 2.5g of 1,6-hexanediol diacrylate and 2.9g of benzoyl peroxide were added to the mixture b, and mechanical stirring was carried out at a speed of 1000rpm until the mixture was uniform, and the stirring time was 5min, to obtain a mixture c;

[0038] Step four: 0.5g of N,N-dimethyl-p-toluidine was added to the mixture c, and mechanical stirring was carried out at a speed of 800rpm until the mixture was uniform, and the stirring time was 1min, and then the mixture was transferred to an oven at 40℃ for reaction and curing for 60min, and the high-stability composite phase change material was obtained after the reaction and curing was completed.

[0039] Example 2:

[0040] A preparation method of a high-stability composite phase change material, the specific steps are as follows:

[0041] Step one: 80g paraffin, 103.4g octadecyl acrylate were placed in an oil bath pot at 60℃ for mixing, mechanical stirring at 300rpm until the solution was uniform, stirring time was 20min, to get mixture a;

[0042] Step two: 12g expanded graphite was slowly added to mixture a in batches, mechanical stirring at 1000rpm until the mixture was uniform, stirring time was 60min, to get mixture b;

[0043] Step three: the temperature of the oil bath pot was adjusted to 40℃, and 2.1g 1,6-hexanediol diacrylate and 2.9g benzoyl peroxide were added to mixture b, mechanical stirring at 1000rpm until the mixture was uniform, stirring time was 5min, to get mixture c;

[0044] Step four: 0.5g N,N-dimethyl-p-toluidine was added to mixture c, mechanical stirring at 800rpm until the mixture was uniform, stirring time was 1min, then the mixture was transferred to an oven at 40℃ for 60min of reaction and curing, after the reaction and curing was completed, a high-stability composite phase change material was obtained.

[0045] Compared with Example 1, the difference is that the mass content of paraffin is changed from 30% to 40%.

[0046] Example 3:

[0047] A preparation method of a high-stability composite phase change material, the specific steps are as follows:

[0048] Step one: 60g tetradecanol, 122.5g octadecyl acrylate were placed in an oil bath pot at 60℃ for mixing, mechanical stirring at 300rpm until the solution was uniform, stirring time was 20min, to get mixture a;

[0049] Step two: 12g expanded graphite was slowly added to mixture a in batches, mechanical stirring at 1000rpm until the mixture was uniform, stirring time was 60min, to get mixture b;

[0050] Step three: the temperature of the oil bath pot was adjusted to 40℃, and 2.5g 1,6-hexanediol diacrylate and 2.9g benzoyl peroxide were added to mixture b, mechanical stirring at 1000rpm until the mixture was uniform, stirring time was 5min, to get mixture c;

[0051] Step four: 0.5 g of N,N-dimethyl-p-toluidine was added to mixture c, and mechanically stirred at 800 rpm until the mixture was uniform, the stirring time was 1 min, then the mixture was transferred to an oven at 40 °C for 60 min of reaction and curing, and the high-stability composite phase change material was obtained after the reaction and curing was completed.

[0052] Compared with Example 1, the difference is that the organic solid-liquid phase change material used is changed from paraffin to tetradecanol.

[0053] Figures 1-3 The composite phase change material obtained in Examples 1-3 exhibits a high melting enthalpy of 110-121 J / g at 46-47 °C according to different contents of organic solid-liquid phase change materials, Figure 4 The mass loss rate of the sample of Example 1 after aging at 55 °C for 120 h is only 0.35 wt%, which is much lower than that of the sample of Example 2. Figure 5 It can be seen that after 30-250 °C cycling, the sample of Example 1 has no collapse in morphology, indicating that the strategy of in-situ crosslinking coating of organic solid-liquid phase change material by octadecyl acrylate / 1,6-hexanediol diacrylate realizes high latent heat and excellent thermal stability at the same time, the formulation is adjustable, the process is low temperature and energy saving, and it can be directly applied to the thermal management of power batteries and electronic devices.

[0054] The DSC test results of the above examples are shown in Table 1:

[0055] Table 1. DSC calculation parameters of different sample examples

Claims

1. A highly stable composite phase change material, characterized in that, This includes organic solid-liquid phase change materials, phase change polymers, and thermal conductive agents.

2. The high-stability composite phase change material according to claim 1, characterized in that, The specific reaction of the phase change polymer is as follows: the reactant octadecyl acrylate and the crosslinking agent 1,6-hexanediol diacrylate undergo a crosslinking reaction under the action of a redox initiation system (benzoyl peroxide and N,N-dimethyl-p-toluidine) to form the polymer.

3. The high-stability composite phase change material according to claim 1, characterized in that, The high-stability composite phase change material comprises, by weight percentage: 30-45% organic solid-liquid phase change material, 55-70% phase change polymer, and 0-6% thermal conductive agent.

4. The specific reaction of the phase change polymer according to claim 2, characterized in that, The molar ratio of octadecyl acrylate to 1,6-hexanediol diacrylate is 40:1, and the amount of benzoyl peroxide is 1% and the amount of N,N-dimethyl-p-toluidine is 0.25% by mass percentage.

5. The high-stability composite phase change material according to claim 1 or 2, characterized in that, The organic solid-liquid phase change material includes at least one of paraffin wax, polyethylene glycol (PM=1500), polyethylene glycol (PM=2000), tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol, tetradecylamine, hexadecylamine, octadecylamine, tetradecyl acid, hexadecyl acid, and octadecyl acid; and the thermal conductive agent includes at least one of expanded graphite, carbon fiber, carbon nanotubes, boron nitride, and graphene.

6. The method for preparing the high-stability composite phase change material according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Mix the organic solid-liquid phase change material and octadecyl acrylate and melt them in an oil bath while mechanically stirring until the solution is homogeneous to obtain mixture a; Step 2: Add the thermal conductive agent slowly in batches to mixture a, and continue to stir mechanically until the mixture is homogeneous, to obtain mixture b; Step 3: Lower the temperature of the oil bath, and add 1,6-hexanediol diacrylate and benzoyl peroxide to mixture b. Continue to stir mechanically until the mixture is homogeneous to obtain mixture c. Step 4: Add N,N-dimethyl-p-toluidine to mixture c, stir mechanically until homogeneous, and then transfer to an oven for curing reaction to obtain a highly stable composite phase change material.

7. The preparation method according to claim 6, characterized in that, In step one, the oil bath temperature is 60℃, the mechanical stirring speed is 300-500 rpm, and the stirring time is 20-30 min. In step two, the mechanical stirring speed is 800-1200 rpm, and the stirring time is 45-60 min.

8. The preparation method according to claim 6, characterized in that, In step three, the oil bath temperature is lowered to 40°C, the mechanical stirring speed is 800–1200 rpm, and the stirring time is 5–10 min.

9. The preparation method according to claim 6, characterized in that, In step four, the mechanical stirring speed is 800-1200 rpm, and the stirring time is 1-2 min.

10. The preparation method according to claim 6, characterized in that, In step four, the oven temperature is 40°C and the curing reaction time is 60 minutes.

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