Preparation method of modified epoxy resin coating coated foamy carbon shaped phase change material

Abstract

The invention provides a preparation method of a modified epoxy resin coating coated foamy carbon shaped phase change material, which comprises the following steps: S1, carbonizing melamine foam to obtain foamy carbon, immersing the foamy carbon into molten paraffin, repeatedly extruding to enable the foamy carbon to adsorb the paraffin, and cooling to obtain shaped paraffin foamy carbon; s2, adding a defoaming agent and acetone into epoxy resin, stirring, adding a curing agent, and continuously stirring to obtain modified epoxy resin; and S3, coating the surface of the paraffin foamy carbon in the step S1 with the modified epoxy resin in the step S2, and curing to obtain the shaped phase change material with the modified epoxy resin coating. The foamy carbon is used as a shaped phase change material, so that high specific surface area and high adsorption rate are provided, and the heat-conducting property is also improved; the paraffin has good heat storage performance and also provides stable heat regulation performance; the epoxy resin coating is coated on the surface of the foamy carbon, so that the mechanical property and the heat transfer property of the paraffin / foamy carbon are improved, and meanwhile, the leakage rate of the phase-change material is also reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of shaped phase change encapsulation materials, and particularly to a preparation method of a modified epoxy resin-coated foam carbon shaped phase change material. Background Art

[0002] Phase change materials (PCMs) have attracted much attention due to their excellent performance in thermal energy storage. During the isothermal phase change process, PCMs can achieve a high energy storage density, which provides strong technical support for applications in multiple fields such as solar / electric heat energy storage, waste heat utilization, building energy conservation, and thermal control.

[0003] Although the application prospects of phase change materials in energy storage are bright, there are still many challenges in the actual application process. For example, solid-liquid phase change materials are prone to leakage during use, and their low thermal conductivity characteristics limit their wide application. The leakage problem of PCMs can be solved by methods such as microencapsulation, electrospinning, and porous structure encapsulation. However, in actual applications, the microencapsulation materials are easily damaged, resulting in the release of phase change materials, affecting their performance and lifespan. And the size of the microencapsulated phase change materials is usually small, which is not suitable for some application scenarios that require a large amount of heat storage.

[0004] Existing encapsulation materials are usually divided into organic materials and inorganic materials. Organic materials have good stability but low thermal conductivity, while inorganic materials have high thermal conductivity but poor thermal stability, which is not conducive to the long-term use of the materials. The shaped phase change heat storage materials can be directly in contact with heat transfer fluid media such as air, without the need for a coil structure to isolate the heat transfer fluid from the phase change material, reducing the heat transfer resistance and cost at the same time. In addition, when the shaped phase change heat storage materials themselves have good forming properties, it is possible to directly construct a heat transfer configuration with a high specific surface area through the shaped phase change heat storage materials. Therefore, it is of great significance to study shaped phase change heat storage encapsulation materials with anti-leakage, good mechanical properties, and thermal conductivity. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a preparation method of a modified epoxy resin-coated foam carbon shaped phase change material. The foam carbon shaped phase change material provides a high specific surface area and high adsorption rate. The modified epoxy resin coating not only greatly prevents the leakage of the phase change material, but also provides good mechanical properties, photothermal conversion, and thermal conductivity through the combination of organic and inorganic materials, realizes the multifunctionalization of the phase change material, and greatly increases the service life of the material.

[0006] The technical solution of the present invention is realized as follows: On the one hand, the present invention provides a preparation method of a modified epoxy resin-coated foam carbon shaped phase change material, including the following steps:

[0007] S1. Melamine foam is carbonized to obtain carbon foam, which is then immersed in molten paraffin. By repeatedly squeezing, the carbon foam adsorbs the paraffin, and after cooling, shaped paraffin carbon foam is obtained.

[0008] S2. Defoamer and acetone are added to epoxy resin. After stirring, a curing agent is added, and continuous stirring yields modified epoxy resin.

[0009] S3. The modified epoxy resin from step S2 is coated on the surface of the paraffin carbon foam from step S1, and after curing, shaped phase change material with a modified epoxy resin coating is obtained.

[0010] Based on the above technical solution, preferably, the preparation of the modified epoxy resin further includes the following steps:

[0011] S21. Carbon nanotubes and nano-silicon carbide powder are ultrasonically dispersed in dimethylformamide, followed by washing and drying to obtain carbon nanotube / silicon carbide composite powder.

[0012] S22. Defoamer, acetone, and the carbon nanotube / silicon carbide composite powder prepared in step S2 are added to epoxy resin. After stirring, a curing agent is added, and continuous stirring yields modified epoxy resin.

[0013] Based on the above technical solution, preferably, in step S21, the mass ratio of carbon nanotubes to nano-silicon carbide powder is 1 - 2:3 - 4.

[0014] Based on the above technical solution, preferably, in step S22, the mass ratio of the epoxy resin:carbon nanotube / silicon carbide powder:defoamer:acetone:curing agent is 100:5 - 9:3 - 5:20 - 30.

[0015] Based on the above technical solution, preferably, in step S1, the melamine foam is washed successively with alcohol and deionized water and then dried; then the dried melamine foam is carbonized in a nitrogen atmosphere, heated to 600 - 700 °C at a rate of 4 - 6 °C / min, carbonized for 0.5 - 1.5 h, and then cooled to obtain carbon foam.

[0016] Based on the above technical solution, preferably, in step S1, the carbon foam adsorbs paraffin under vacuum conditions, with a vacuum degree of 10 -1 ~10 -2 Pa, and the vacuum adsorption is carried out for 1 - 2 h.

[0017] Based on the above technical solution, preferably, in step S1, the mass ratio of carbon foam to paraffin is 1:2 - 3.

[0018] Based on the above technical solution, preferably, in step S21, the mass ratio of carbon nanotubes to nano-silicon carbide powder is 1 - 2:3 - 4.

[0019] On the basis of the above technical solutions, preferably, in step S22, the mass ratio of the epoxy resin: carbon nanotube / silicon carbide powder: defoamer: acetone: curing agent is 100:5-9:3-5:20-30.

[0020] On the basis of the above technical solutions, preferably, in step S2, the mass ratio of the epoxy resin to the curing agent is 3-5:1.

[0021] On the basis of the above technical solutions, preferably, in step S2, the stirring speed is 100-130 r / min, and the mechanical stirring time is 20-30 min.

[0022] On the basis of the above technical solutions, preferably, in step S2, the curing time is 24-48 h, and the curing temperature is 20-30 °C.

[0023] On the basis of the above technical solutions, preferably, the epoxy resin is E44 epoxy resin, the defoamer is silicone defoamer, and the curing agent is amine curing agent.

[0024] On the other hand, the present invention also provides an application of the shaped phase change material prepared by the preparation method of the modified epoxy resin coated foam carbon shaped phase change material in packaging materials.

[0025] The preparation method of the modified epoxy resin coated foam carbon shaped phase change material of the present invention has the following beneficial effects compared with the prior art:

[0026] (1) The present invention uses foam carbon as the shaped phase change material, providing a high specific surface area and high adsorption rate, and also improving the thermal conductivity; at the same time, using the good heat storage performance of paraffin wax to provide stable thermal regulation performance. Since the exposed paraffin wax / foam carbon is extremely vulnerable to the environment during use, in a humid or high-temperature environment, the foam carbon is easy to absorb moisture, resulting in a poor adsorption capacity and hindering the heat transfer process of the material. Coating an epoxy resin coating on its surface can effectively solve these problems. In addition, its high coating rate greatly reduces the leakage rate of the phase change material.

[0027] (2) After adding carbon nanotube / silicon carbide as a filler to the epoxy resin, the hardness and strength of the epoxy resin can be improved, the external force can be effectively dispersed, the fatigue resistance of the composite material can be improved, and the thermal conductivity can be further enhanced. In addition, the addition of the composite powder also enhances the flame retardant performance of the material, broadens the application scenarios of the material, and can be applied to industries such as electronics, electrical and aerospace.

[0028] (3) The synergistic effect of carbon nanotube / silicon carbide composite powder and epoxy resin improves the barrier performance of the composite material, reduces gas and liquid penetration, and further decreases the leakage rate of the phase change material. The good photothermal conversion ability of carbon nanotubes greatly enhances the photothermal conversion performance of the phase change material, achieving a high photothermal conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 SEM image of the material obtained in Example 1;

[0031] Figure 2 DSC diagrams of the materials obtained in Examples 1-4;

[0032] Figure 3 Leakage test diagrams of the materials obtained in Examples 1-4 and Comparative Example 1;

[0033] Figure 4 Photothermal conversion curve diagrams of the materials obtained in Examples 1-4;

[0034] Figure 5 Thermal conductivity diagrams of the materials obtained in Examples 1-4 and Comparative Example 1;

[0035] Figure 6 Stress-strain curves of the materials obtained in Examples 1-2 and Comparative Example 1 under compressive force;

[0036] Figure 7 Relationship curve between the mass fraction of CNTs / SiC in epoxy resin and oxygen index. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0038] The epoxy resin used in the present invention is E44 epoxy resin, purchased from Shanghai Macklin Biochemical Co., Ltd.; the paraffin wax is sectioning paraffin wax with the national drug code 69019563, purchased from Shanghai Sinopharm Chemical Reagent Co., Ltd.; the defoaming agent is silicone defoaming agent with the model number M756786, purchased from Shanghai Macklin Biochemical Co., Ltd.; the curing agent is amine curing agent with the model number A875163, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0039] Example 1

[0040] A preparation method of a modified epoxy resin-coated foam carbon shaped phase change material in this example is achieved through the following technical solutions:

[0041] S1, carbonizing melamine foam:

[0042] S11, ultrasonic wash melamine foam with length, width and height of 35mm×40mm×20mm with alcohol and deionized water for 1h respectively, and then dry it.

[0043] S12, place the washed and dried melamine foam in a tubular high-temperature resistance furnace under a nitrogen atmosphere, heat it to 600°C at a rate of 5°C / min, carbonize for 1h, and then naturally cool to obtain foam carbon.

[0044] S2, foam carbon adsorbing paraffin wax:

[0045] Take 20g of paraffin wax and heat it to melt in an oven at 90°C. Put 10g of foam carbon into a beaker containing the melted paraffin wax, squeeze out the air bubbles repeatedly to make the foam carbon fully adsorb the paraffin wax, and perform vacuum adsorption for 1h with a vacuum degree of 10 -2 pa, and cool it at room temperature for 2h to obtain shaped paraffin / foam carbon.

[0046] S3, preparation of modified epoxy resin:

[0047] S31, add 5g of defoaming agent and 25g of acetone to 100g of epoxy resin, and mechanically stir at a speed of 130r / min for 20min to make the composite powder disperse evenly.

[0048] S32, according to the ratio of epoxy resin to curing agent of 4:1, add 16.25g of curing agent to the homogeneous solution obtained in S41, and continue to mechanically stir for 20min to obtain modified epoxy resin.

[0049] S4, evenly coat the modified epoxy resin on the surface of paraffin / foam carbon with a silicone brush, with a thickness of 50μm, and cure it at room temperature for 24h to obtain a shaped phase change material with a modified epoxy resin coating.

[0050] Example 2

[0051] A preparation method of a modified epoxy resin-coated foam carbon shaped phase change material in this embodiment is achieved through the following technical solutions:

[0052] S1, carbonized melamine foam:

[0053] S11, Ultrasonically wash melamine foam with dimensions of 35 mm × 40 mm × 20 mm with alcohol and deionized water for 1 h respectively, and then dry it.

[0054] S12, Place the washed and dried melamine foam in a tubular high-temperature resistance furnace under a nitrogen atmosphere, heat it to 600 °C at a rate of 5 °C / min, carbonize for 1 h, and then naturally cool to obtain foam carbon.

[0055] S2, Foam carbon adsorbing paraffin:

[0056] Take 20 g of paraffin and heat it to melt in an oven at 90 °C. Put 10 g of foam carbon into a beaker containing the melted paraffin, squeeze out the bubbles repeatedly to make the foam carbon fully adsorb the paraffin, and then perform vacuum adsorption for 1 h with a vacuum degree of 10 -2 Pa. After cooling at room temperature for 2 h, shaped paraffin / foam carbon is obtained.

[0057] S3, Preparation of carbon nanotube / silicon carbide composite powder:

[0058] S31, Take 5 g of carbon nanotubes and add them to 95 g of dimethylformamide solvent, and ultrasonically disperse for 40 min to obtain a uniform dispersion of carbon nanotubes. The mass fraction of the dimethylformamide solvent is 95%.

[0059] S32, Add 7.5 g of nano-silicon carbide powder to the dispersion in S31, continue to ultrasonically disperse for 1 h to obtain a uniform dispersion, filter it, wash it 3 times with anhydrous ethanol and deionized water respectively, and then dry it in vacuum at 60 °C for 12 h to obtain carbon nanotube / silicon carbide composite powder.

[0060] S4, Preparation of modified epoxy resin:

[0061] S41, Add 5 g of carbon nanotube / silicon carbide composite powder, 5 g of defoamer, and 25 g of acetone to 100 g of epoxy resin, and mechanically stir at a speed of 130 r / min for 20 min to make the composite powder disperse evenly.

[0062] S42, According to the ratio of epoxy resin to curing agent of 4:1, add 16.25 g of curing agent to the homogeneous solution obtained in S41, and continue to mechanically stir for 20 min to obtain modified epoxy resin.

[0063] S5, Use a silicone brush to evenly coat the modified epoxy resin on the surface of paraffin / foam carbon with a thickness of 50 μm, and cure it at room temperature for 24 h to obtain a shaped phase change material with a modified epoxy resin coating.

[0064] Example 3

[0065] Compared with Example 2, the preparation method of the modified epoxy resin is different, specifically as follows:

[0066] S41, Add 7 g of carbon nanotube / silicon carbide composite powder, 5 g of defoamer, and 25 g of acetone to 100 g of epoxy resin, and mechanically stir at a speed of 130 r / min for 20 min to evenly disperse the composite powder.

[0067] S42, Add 16.25 g of curing agent to the homogeneous solution obtained in S41 at a ratio of epoxy resin to curing agent of 4:1, and continue mechanical stirring for 20 min to obtain the modified epoxy resin.

[0068] The rest is the same as Example 2.

[0069] Example 4

[0070] Compared with Example 2, the preparation method of the modified epoxy resin is different, specifically as follows:

[0071] S41, Add 9 g of carbon nanotube / silicon carbide composite powder, 5 g of defoamer, and 25 g of acetone to 100 g of epoxy resin, and mechanically stir at a speed of 130 r / min for 20 min to evenly disperse the composite powder.

[0072] S42, Add 16.25 g of curing agent to the homogeneous solution obtained in S41 according to the ratio of epoxy resin to curing agent of 4:1, and continue mechanical stirring for 20 min to obtain the modified epoxy resin.

[0073] The rest is the same as Example 2.

[0074] Example 5

[0075] The preparation method of a modified epoxy resin-coated foam carbon shaped phase change material in this example is realized through the following technical solutions:

[0076] S1, Carbonize melamine foam:

[0077] S11, Ultrasonically wash the melamine foam with length, width and height of 35 mm×40 mm×20 mm with alcohol and deionized water for 1 h respectively, and dry.

[0078] S12, Place the washed and dried melamine foam in a tubular high-temperature resistance furnace under a nitrogen atmosphere, heat it from 4°C to 650°C, carbonize it for 1.5 h, and naturally cool it to obtain foam carbon.

[0079] S2, Adsorb paraffin on foam carbon:

[0080] Take 30 g of paraffin wax and heat it to melt in an oven at 90 °C. Put 10 g of carbon foam into a beaker containing the melted paraffin wax, and squeeze it repeatedly to expel air bubbles and make the carbon foam fully adsorb the paraffin wax. Then perform vacuum adsorption for 2 h with a vacuum degree of 10 -1 Pa, and cool it at room temperature for 2 h to obtain shaped paraffin wax / carbon foam

[0081] S3. Preparation of carbon nanotube / silicon carbide composite powder:

[0082] S31. Take 5 g of carbon nanotubes and add them to 95 g of dimethylformamide solvent, and perform ultrasonic dispersion for 40 min to obtain a uniform dispersion of carbon nanotubes. The mass fraction of the dimethylformamide solvent is 95%.

[0083] S32. Add 15 g of nano-silicon carbide powder to the dispersion obtained in S31, continue ultrasonic dispersion for 1 h to obtain a uniform dispersion, filter it, wash it 3 times with absolute ethanol and deionized water respectively, and then perform vacuum drying at 60 °C for 12 h to obtain carbon nanotube / silicon carbide composite powder. The mass ratio of carbon nanotubes to silicon carbide is 1:3.

[0084] S4. Preparation of modified epoxy resin:

[0085] S41. Add 6 g of carbon nanotube / silicon carbide composite powder, 3 g of defoamer, and 20 g of acetone to 100 g of epoxy resin, and perform mechanical stirring at a speed of 100 r / min for 25 min to make the composite powder disperse evenly

[0086] S42. According to the mass ratio of epoxy resin to curing agent of 5:1, add the curing agent to the homogeneous solution obtained in S41, and continue mechanical stirring for 20 min to obtain modified epoxy resin

[0087] S5. Use a silicone brush to evenly coat the modified epoxy resin on the surface of paraffin wax / carbon foam with a thickness of 50 μm, and cure it at room temperature for 36 h to obtain a shaped phase change material with a modified epoxy resin coating

[0088] Example 6

[0089] A preparation method of a modified epoxy resin-coated carbon foam shaped phase change material in this example is realized through the following technical solutions:

[0090] S1. Carbonize melamine foam:

[0091] S11. Ultrasonically wash melamine foam with dimensions of 35 mm × 40 mm × 20 mm with alcohol and deionized water for 1 h respectively, and then dry it.

[0092] S12. Place the cleaned and dried melamine foam in a tube-type high-temperature resistance furnace under a nitrogen atmosphere, heat it to 700 °C at a rate of 6 °C / min for carbonization for 0.5 h, and obtain carbon foam after natural cooling.

[0093] S2. Adsorb paraffin on the carbon foam:

[0094] Take an appropriate amount of paraffin and heat it to melt in an oven at 90 °C. Put the carbon foam into a beaker containing the melted paraffin, squeeze out the air bubbles repeatedly and make the carbon foam fully adsorb the paraffin. Adsorb it under vacuum for 1 h and cool it at room temperature for 2 h to obtain the shaped paraffin / carbon foam.

[0095] S3. Preparation of carbon nanotube / silicon carbide composite powder:

[0096] S31. Take an appropriate amount of carbon nanotubes and add them to dimethylformamide solvent for ultrasonic dispersion for 40 min to obtain a uniform dispersion of carbon nanotubes. The mass fraction of the dimethylformamide solvent is 95%.

[0097] S32. Add nano-silicon carbide powder to the dispersion obtained in S31, continue ultrasonic dispersion for 1 h to obtain a uniform dispersion, filter it and wash it 3 times with anhydrous ethanol and deionized water respectively, and then dry it in vacuum at 60 °C for 12 h to obtain carbon nanotube / silicon carbide composite powder. The mass ratio of carbon nanotubes to silicon carbide is 2:3.

[0098] S4. Preparation of modified epoxy resin:

[0099] S41. Add 8 g of carbon nanotube / silicon carbide composite powder, 4 g of defoaming agent, and 30 g of acetone to 100 g of epoxy resin, and mechanically stir it at a speed of 120 r / min for 30 min to make the composite powder disperse evenly.

[0100] S42. According to the mass ratio of epoxy resin to curing agent of 100:30, add the curing agent to the homogeneous solution obtained in S41, and continue mechanical stirring for 20 min to obtain the modified epoxy resin.

[0101] S5. Use a silica gel brush to evenly coat the modified epoxy resin on the surface of the paraffin / carbon foam with a thickness of 50 μm, and cure it at room temperature for 48 h to obtain the shaped phase change material with a modified epoxy resin coating.

[0102] Comparative Example 1

[0103] Compared with Example 1, in Comparative Example 1, no modified epoxy resin is added. The specific preparation method of the phase change material is as follows:

[0104] S1. Carbonize the melamine foam: the same as in Example 1.

[0105] S2. Adsorb paraffin on the carbon foam: the same as in Example 1.

[0106] Comparative Example 2

[0107] Compared with Example 2, the carbon foam does not adsorb paraffin. The specific preparation method of the phase change material is as follows:

[0108] S1. Carbonized melamine foam: The same as in Example 2.

[0109] S2. Preparation of carbon nanotube / silicon carbide composite powder: The same as in Example 2.

[0110] S3. Preparation of modified epoxy resin: The same as in Example 2.

[0111] S4. Use a silicone brush to evenly coat the modified epoxy resin on the surface of the carbon foam with a thickness of 50 μm, and cure it at room temperature for 24 h to obtain carbon foam with a modified epoxy resin coating.

[0112] Comparative Example 3

[0113] Compared with Example 2, the modified epoxy resin lacks nano-silicon carbide powder. The specific preparation method of the phase change material is as follows:

[0114] S1. Carbonized melamine foam: The same as in Example 2.

[0115] S2. Carbon foam adsorbing paraffin: The same as in Example 2.

[0116] S3. Preparation of modified epoxy resin: The same as in Example 2.

[0117] S31. Add 5 g of carbon nanotube powder, 5 g of defoamer, and 25 g of acetone to 100 g of epoxy resin, and mechanically stir at a rate of 130 r / min for 20 min to make the powder evenly dispersed.

[0118] S32. Add a curing agent to the homogeneous solution obtained in S31 at a ratio of epoxy resin to curing agent of 4:1, and continue mechanical stirring for 20 min to obtain a modified epoxy resin.

[0119] S4. Use a silicone brush to evenly coat the modified epoxy resin on the paraffin / carbon foam surface with a thickness of 50 μm, and cure it at room temperature for 24 h to obtain a shaped phase change material with a modified epoxy resin coating.

[0120] Comparative Example 4

[0121] Compared with Example 2, the modified epoxy resin lacks nano-carbon nanotube powder. The specific preparation method of the phase change material is as follows:

[0122] S1. Carbonized melamine foam: The same as in Example 2.

[0123] S2. Carbon foam adsorbing paraffin: The same as in Example 2.

[0124] S3. Preparation of modified epoxy resin: The same as in Example 2.

[0125] S31. Add 5 g of silicon carbide powder, 5 g of defoamer, and 25 g of acetone to 100 g of epoxy resin, and mechanically stir at a speed of 130 r / min for 20 min to uniformly disperse the powder.

[0126] S32. Add a curing agent to the homogeneous solution obtained in S31 at a ratio of epoxy resin to curing agent of 4:1, and continue mechanical stirring for 20 min to obtain a modified epoxy resin.

[0127] S4. Uniformly coat the modified epoxy resin on the surface of paraffin / foamed carbon with a silicone brush to a thickness of 50 μm, and cure at room temperature for 24 h to obtain a shaped phase change material with a modified epoxy resin coating.

[0128] Comparative Example 5

[0129] Compared with Example 2, the dosage of carbon nanotube / silicon carbide composite powder in Comparative Example 5 exceeds the specified range. The specific preparation method of the phase change material is as follows:

[0130] S1. Carbonized melamine foam: The same as in Example 2.

[0131] S2. Foamed carbon adsorbing paraffin: The same as in Example 2.

[0132] S3. Preparation of carbon nanotube / silicon carbide composite powder: The same as in Example 2.

[0133] S4. Preparation of modified epoxy resin:

[0134] S41. Add 11 g of carbon nanotube / silicon carbide composite powder, 5 g of defoamer, and 25 g of acetone to 100 g of epoxy resin, and mechanically stir at a speed of 130 r / min for 20 min to uniformly disperse the composite powder.

[0135] S42. According to the ratio of epoxy resin to curing agent of 4:1, add 16.25 g of curing agent to the homogeneous solution obtained in S41, and continue mechanical stirring for 20 min to obtain a modified epoxy resin.

[0136] S5. Uniformly coat the modified epoxy resin on the surface of paraffin / foamed carbon with a silicone brush to a thickness of 50 μm, and cure at room temperature for 24 h to obtain a shaped phase change material with a modified epoxy resin coating.

[0137] Detect the performance of the phase change materials prepared in the examples and comparative examples. The detection method is as follows, and the results are shown in Table 1 and Figure 2-7 .

[0138] Thermal diffusivity: The phase change behavior of the composite phase change material was studied by a differential scanning calorimeter at a heating rate of 10 °C / min in a nitrogen atmosphere from 0 °C to 90 °C.

[0139] Leakage rate test: To study the shape stability of the composite phase change material, the corresponding sample was placed on a constant temperature heating table at 90 °C and observed continuously for 60 min, and the weight retention rate of the composite phase change material was recorded. Leakage rate = 1 - weight retention rate.

[0140] Photothermal conversion rate: The photothermal conversion performance of the sample was tested using a self-built photothermal conversion test system, and the power of the simulated sunlight was 400 mW·cm -2 , and the light source was turned off after 500 s.

[0141] Thermal conductivity: The thermal diffusivity was obtained at room temperature using a laser thermal conductivity meter.

[0142] Mechanical properties: The mechanical properties of the sample under compressive force were tested using an electronic universal material testing machine.

[0143] Flammability: The oxygen content of the composite phase change material was tested using a limiting oxygen index instrument.

[0144] Table 1 Properties of the phase change material

[0145]

[0146] Figure 1 It is the scanning electron microscope image of the material obtained in Example 1. It can be seen from the figure that the epoxy resin coating is coated on the surface of the foam carbon. This coating can not only prevent the leakage of the phase change material, but also improve the stability of the phase change material, avoiding the problem that it absorbs moisture under humid or high-temperature conditions and hinders the heat transfer process of the material.

[0147] Table 1 and Figure 2 As can be seen, the thermal diffusivity and thermal conductivity of Examples 2-4 are higher than those of Example 1 because the addition of carbon nanotube / silicon carbide enhances the thermal conductivity of the phase change material.

[0148] It can be seen from Example 1 and Comparative Example 1 that after the epoxy resin is coated on the surface of the foam carbon, the leakage rate of the phase change material is greatly reduced; compared with Example 1, in Examples 2-3, due to the addition of carbon nanotube / silicon carbide composite powder, the barrier performance of the composite phase change material is improved, thereby reducing the gas and liquid penetration and lowering the leakage rate of the phase change material (see Table 1 and Figure 3 ).

[0149] Figure 4 It can be seen that Examples 2-3 show a relatively high photothermal conversion effect, and Example 4 has the best photothermal conversion effect. Examples 2-4 show relatively high thermal conductivity (see Table 1 and Figure 5) It shows that the addition of carbon nanotube / silicon carbide composite powder improves the thermal conductivity of the phase change material.

[0150] Table 1 and Figure 6 As shown, compared with Comparative Example 1, the mechanical properties of the phase change material are increased after the surface of Example 1 is coated with epoxy resin. On this basis, further adding carbon nanotube / silicon carbide composite powder (Examples 2-5) can further improve the mechanical properties of the phase change material.

[0151] Figure 7 As shown, the oxygen index increases with the increase of the CNTs / SiC content, indicating that the flame retardancy improves with the increase of the CNTs / SiC content. Considering the comprehensive performance of the composite phase change material, the performance is the best when the CNTs / SiC content is 5% - 9%.

[0152] From Comparative Example 2, it can be seen that the carbon foam does not adsorb paraffin, so it is an ordinary thermal conductive foam, and its phase change energy storage capacity is greatly reduced; the strength of the carbon foam skeleton is also insufficient and it is easy to break.

[0153] From Comparative Examples 3 and 4, it can be seen that when the carbon nanotube or silicon carbide composite powder is missing, the toughness of the epoxy resin is insufficient, and the barrier property of the coating only depends on the resin itself. Since the thermal expansion coefficient of the resin does not match that of the carbon foam, it will cause an increase in interfacial microcracks and the formation of permeation channels, thereby increasing the leakage rate of the final phase change material and reducing the mechanical strength, thermal regulation performance and flame retardancy of the phase change material.

[0154] From Comparative Example 5, it can be seen that after the amount of carbon nanotube / silicon carbide composite powder exceeds the specified range, the excessive powder will interfere with the formation of a continuous film of the coating, thereby generating micropores and cracks, weakening the barrier effect, increasing the leakage rate of the phase change material, and reducing the flame retardancy, heat storage capacity and mechanical strength.

[0155] In summary, the modified epoxy resin coating prepared by the present invention coated on the carbon foam adsorbing paraffin shows excellent thermal conductivity, photothermal conversion property and good mechanical properties, as well as a low leakage rate, realizing the multifunctionalization of the phase change material.

[0156] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material, characterized in that: The following steps are involved: S1, carbonizing melamine foam to obtain foam carbon, then immersing it in melted paraffin, repeatedly squeezing the foam carbon to make it absorb the paraffin, and obtaining a fixed paraffin foam carbon after cooling; S2, adding a defoamer and acetone to the epoxy resin, stirring, adding a curing agent, and continuing to stir to obtain a modified epoxy resin; S3, coating the modified epoxy resin of step S2 on the surface of the paraffin foam carbon of step S1, and obtaining a fixed phase change material with a modified epoxy resin coating after curing.

2. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 1, characterized in that: The preparation of the modified epoxy resin also includes the following steps: S21, ultrasonically dispersing the carbon nanotubes and nano-silicon carbide powder in dimethylformamide, followed by washing and drying to obtain a carbon nanotube / silicon carbide composite powder; S22, adding a defoaming agent, acetone and the carbon nanotube / silicon carbide composite powder prepared in step S2 into the epoxy resin, stirring, adding a curing agent, and continuing to stir to obtain a modified epoxy resin.

3. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 2, characterized in that: In step S21, the mass ratio of carbon nanotubes to nano silicon carbide powder is 1-2:3-4.

4. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 2, characterized in that: In step S22, the mass ratio of the epoxy resin: carbon nanotube / silicon carbide powder: defoamer: acetone: curing agent is 100:5-9:3-5:20-30.

5. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 1, characterized in that: In step S1, the melamine foam is washed with alcohol and deionized water in sequence and dried; the dried melamine foam is then carbonized in a nitrogen atmosphere, heated to 600-700° C. at 4-6° C. / min, carbonized for 0.5-1.5 h, and then cooled to obtain foamed carbon.

6. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 1, characterized in that: In step S1, the foamed carbon adsorbs paraffin under vacuum conditions, and the vacuum degree is 10 -1 ~10 -2 pa, vacuum adsorption for 1-2h.

7. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 1, characterized in that: In step S1, the mass ratio of foamed carbon to paraffin is 1:2-3.

8. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 1, characterized in that: In step S2, the stirring speed is 100-130 r / min, and the mechanical stirring time is 20-30 min.

9. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 1, characterized in that: In step S2, the curing time is 24 to 48 hours and the curing temperature is 20 to 30°C.

10. The method for preparing a modified epoxy resin coating-coated carbon foam shaped phase change material according to claim 1, characterized in that: The epoxy resin is E44 epoxy resin, the defoamer is an organosilicon defoamer, and the curing agent is an amine curing agent.

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