Preparation method of phase change microcapsule and phase change microcapsule-doped epoxy resin self-repairing composite insulating material

Abstract

The invention discloses a phase change microcapsule and a preparation method of an epoxy resin self-repairing composite insulating material doped with the phase change microcapsule, the phase change microcapsule self-repairing epoxy resin composite material is of a core-shell structure, 500nm silicon carbide particles and octacosane are used as cores, and the outer layer is coated with Fe3O4 coated SiO2 nanoparticles. In the aspect of heat-conducting property, the heat-conducting property of the epoxy resin composite material is gradually increased along with the increase of the microcapsule content from 0 wt%. Due to the fact that microcapsules with Fe3O4 coated SiO2 nanoparticles as shells are added and interconnected to form a heat conduction network, the overall heat conduction performance of the material is improved; the microencapsulated repairing agent disclosed by the invention not only can heal cracks, but also can provide higher tensile property for damaged parts of the epoxy resin composite material.

Description

Technical Field

[0001] The present invention belongs to the field of materials science, and particularly relates to a preparation method of a phase change microcapsule and an epoxy resin self-healing composite insulating material doped with the phase change microcapsule. Background Art

[0002] Polymer matrix composites are materials composed of polymer materials and reinforcing materials with characteristics such as high strength, high modulus, and temperature resistance. Such composites usually have characteristics such as high specific strength and specific modulus, good resistance to chemical corrosion, and excellent machining properties, so they have been widely used in the fields of aerospace, automobiles, sports equipment, etc. Epoxy resin is generally considered to be a composite matrix with excellent performance due to its good adhesion performance and low curing shrinkage rate. However, in the context of insulation, the defect that micro-damage inside epoxy resin-based materials is difficult to detect or repair in a timely manner seriously hinders its further popularization and application in the high-voltage field.

[0003] During the actual application process of epoxy resin-based composite insulating materials, due to defects in manufacturing processes, transportation conditions, installation methods and the influence of complex working environments of strong magnetism and strong electricity, micro-crack damages are inevitably generated inside the insulating materials. However, there is currently no effective solution to the problem of micro-damage deterioration inside epoxy resin-based insulating composites. Most of the research on effectively preventing micro-crack damages inside epoxy resin-based composite insulating materials focuses on improving the electrical breakdown performance of epoxy resin-based composite insulating materials and increasing the dielectric constant of insulating materials by means of nano-doping, while there is a lack of corresponding research on how to efficiently self-repair internal damages.

[0004] The curing mechanism of microcapsules in epoxy resin-based composite insulating materials is usually to coat a liquid repair agent inside the microcapsule wall. When the damage breaks the capsule wall, the repair agent flows out to fill the damage channel and cures under external conditions such as temperature and light to achieve the repair of the insulating material for the damage. Since the components after curing of the existing repair agents are not exactly the same as those of the epoxy resin matrix, intrinsic defects will appear at the repair interface of the epoxy resin-based composite insulating materials, resulting in a decrease in the mechanical properties of the epoxy resin-based composite insulating materials, which limits the wide application of the current microcapsule self-healing technology in the fields of high voltage and insulation technology.

[0005] The existing microcapsule self-healing technology has made great progress in the field of self-healing of epoxy resin-based composite insulating materials. The microcapsule repair agents in epoxy resin-based composite insulating materials need to be induced to cure by external excitation or through chemical reactions. This curing process is irreversible and can only be repaired once. To solve the problems of irreversible curing and single repair of traditional repair agents, it is urgent to improve the existing technology and innovatively develop a high-performance epoxy resin self-healing composite insulating material with a recyclable path. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract, and the title, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0007] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0008] Therefore, an object of the present invention is to overcome the deficiencies in the prior art and provide a preparation method for a phase change microcapsule and an epoxy self-healing composite insulating material doped with the phase change microcapsule.

[0009] To solve the above technical problems, the present invention provides the following technical solution: A phase change microcapsule, characterized in that: the phase change microcapsule has a core-shell structure, wherein, silicon carbide particles and octacosane are used as the core, and the outer layer is coated with Fe3O4@SiO2 nanoparticles.

[0010] Another object of the present invention is to overcome the deficiencies in the prior art and provide a preparation method for a phase change microcapsule, characterized in that: it includes,

[0011] Dissolve Fe3O4 nanoparticles in absolute ethanol and ultrasonically disperse to obtain dispersion solution 1; dropwise add concentrated ammonia water to dispersion solution 1 to obtain dispersion solution 2; dropwise add tetraethyl orthosilicate to dispersion solution 2 to obtain dispersion solution 3;

[0012] Mix and stir dispersion solution 3 under heating conditions, after solid-liquid separation, filter and wash with methanol and deionized water respectively, and dry at room temperature to obtain Fe3O4@SiO2 nanoparticles;

[0013] Dissolve Fe3O4@SiO2 nanoparticles in a cetyltrimethylammonium bromide solution to obtain an aqueous solution; add silicon carbide particles to octacosane to obtain an oil phase solution;

[0014] Stir the oil phase solution and the aqueous solution at room temperature to obtain an oil-water emulsion, filter and wash with methanol and deionized water respectively, and dry at room temperature to obtain the phase change microcapsule.

[0015] As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of the Fe3O4 nanoparticles to the absolute ethanol is 1.0 - 1.1:35 - 40.

[0016] As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of the dispersion solution 1 to the concentrated ammonia water is 1.0 - 1.2:1.5 - 1.7; the mass ratio of the tetraethyl orthosilicate to the dispersion solution 2 is 1.0 - 1.1:42 - 45.

[0017] As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of the aqueous solution to the oil phase solution is 18-22:12-15.

[0018] As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of Fe3O4@SiO2 nanoparticles to tetradecyltrimethylammonium bromide in the aqueous solution is 0.9-1.3:30-38. As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of silicon carbide particles to octacosane in the oil phase solution is 1.1-1.4:30-34.

[0019] Another object of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of an epoxy resin self-healing composite insulating material doped with phase change microcapsules, which is characterized in that: it includes,

[0020] Using room temperature curing epoxy resin and curing agent as the matrix; mixing the phase change microcapsules with the matrix, degassing the mixed sample, and curing at room temperature to obtain the doped phase change microcapsule epoxy resin self-healing composite insulating material.

[0021] As a preferred embodiment of the preparation method of the present invention, wherein: the mass ratio of the room temperature curing epoxy resin to the curing agent is 1.0-1.2:0.65-0.85.

[0022] As a preferred embodiment of the preparation method of the present invention, wherein: the total content of the phase change microcapsules is 2-8 wt%.

[0023] Advantages of the present invention:

[0024] In terms of thermal conductivity of the present invention, as the content of the microcapsules increases from 0 wt%, the thermal conductivity of the epoxy resin-based composite insulating material shows an upward trend. Since the addition of microcapsules with Fe3O4@SiO2 nanoparticles as the shell increases the overall thermal conductivity of the material; the microencapsulated healing agent of the present invention can not only heal cracks, but also provide good thermal conductivity for the epoxy resin-based composite insulating material. Description of the drawings

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0026] Figure 1 It is a scanning electron microscope characterization diagram of 500 nm silicon carbide particles and octacosane microcapsules with Fe3O4@SiO2 nanoparticles as the shell of the present invention.

[0027] Figure 2 Bar chart of the influence of different microcapsule contents on the thermal conductivity of epoxy resin-based composite insulating materials in the embodiments and comparative examples of the present invention.

[0028] Figure 3 Scratch damage self-healing effect diagram of the phase change microcapsule self-healing epoxy resin-based composite insulating material of the present invention.

[0029] Figure 4 Bar chart of the tensile strength of epoxy resin composites with different microcapsule contents in the embodiments and comparative examples of the present invention.

[0030] Figure 5 Bar chart of the influence of different microcapsule contents of the repair agent on the self-healing efficiency of epoxy resin composites in the embodiments and comparative examples of the present invention. Detailed implementation manners

[0031] To make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention will be given in conjunction with the embodiments of the specification.

[0032] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0033] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that is mutually exclusive with other embodiments.

[0034] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available. The details are shown in Table 1.

[0035] Table 1

[0036]

[0037]

[0038] The performance test methods for the doped phase change microcapsule-containing epoxy resin self-healing composite insulating materials prepared in the embodiments and comparative examples of the present invention refer to:

[0039] Tensile Strength Test: This tensile strength test was carried out in accordance with "GB / T 1040.2-2003 Plastics - Determination of tensile properties - Part 2: Test conditions for moulding and extrusion plastics" and "GB / T 41929-2022 Plastics - Test methods for epoxy resins". According to the standard requirements, epoxy resin specimens with standard dimensions were prepared, and the specific dimensions are as follows: length L = 150 mm, width b = 10 mm ± 0.1 mm, thickness d = 4 mm ± 0.1 mm, gauge length L0 = 50 mm (i.e., the initial distance between the two clamps). An electronic universal material testing machine, model WDW-100E (maximum test force 100 kN, accuracy class 1), equipped with standard tensile clamps and an extensometer (for measuring deformation), was selected. The experimental steps are as follows: First, use a vernier caliper or micrometer to measure the dimensions of the specimen to ensure that they meet the standard requirements and record the data. Then, clean the surface of the specimen with alcohol and cotton swabs to remove dust and impurities, ensuring that the surface is clean and undamaged. Finally, check whether the power supply, sensors, and control system of the testing machine are normal to ensure that the load sensor and displacement sensor have been calibrated. Install the appropriate tensile clamps and extensometer, and adjust their positions and gauge length. Clamp the two ends of the specimen in the upper and lower clamps respectively, ensuring that the specimen is centered and firmly clamped. Check whether the loading direction of the specimen is consistent with the tensile direction of the testing machine. Set the tensile speed to 5 mm / min and the test mode to stress-strain mode in the control software of the testing machine. Start the testing machine to begin the tensile test, observe the deformation of the specimen, and record the changes in load and displacement. When the specimen breaks, the testing machine automatically stops the test and records the maximum load at the time of fracture. Statistically analyze the test data of multiple specimens and calculate the average value and standard deviation.

[0040] Thermal Conductivity Test: This thermal conductivity test is carried out in accordance with the "ASTM E1461 Standard Test Method: Measurement of Thermal Diffusivity by the Flash Method" and refers to relevant thermal conductivity test standards for operation. According to the standard requirements, circular epoxy resin specimens are prepared with the following specific dimensions: diameter D = 12.7 mm, thickness d = 2 mm. A laser thermal conductivity meter, model LFA 447, is selected. This instrument is designed based on the laser flash method and is suitable for measuring the thermal diffusivity and thermal conductivity of materials. First, circular epoxy resin specimens with a diameter of 12.7 mm and a thickness of 2 mm are prepared to ensure that the specimen surfaces are flat. Then, the specimen surfaces are spray-coated with graphite to increase the light absorption ratio and infrared emissivity of the specimen surfaces. Start the laser thermal conductivity meter and turn on the water bath device, and keep it for more than 30 minutes to make the equipment in a stable state. Place the sample tray at the test position to ensure that the sample is tested under a protective atmosphere. Start the laser thermal conductivity meter, and a light pulse is instantaneously emitted by the laser source and uniformly irradiated on the lower surface of the sample, causing its temperature to rise after absorbing the light energy. Use an infrared detector to continuously measure the temperature rise process of the upper surface of the sample and record the relationship curve of temperature rise versus time. Calculate the thermal diffusivity (α) through the analysis software, and combine the specific heat capacity (Cp) and density (ρ) of the sample to calculate the thermal conductivity (λ): λ = α × Cp × ρ, where the specific heat capacity can be obtained through testing with a differential scanning calorimeter (DSC).

[0041] Self-healing efficiency test: This electrical performance test is based on "GB / T 1408.1-2017 Measurement of dielectric properties of plastic insulating materials and bonded insulating materials - Part 1: General guidelines" and "GB / T 1408.2-2017 Measurement of dielectric properties of plastic insulating materials and bonded insulating materials - Part 2: Measurement of dielectric dissipation factor tangent". According to the standard requirements, circular epoxy resin specimens are prepared with the following specific dimensions: diameter D = 25 mm and thickness d = 2 mm. A power frequency high-voltage breakdown platform, model ZJC-50E, is selected. This instrument is suitable for the breakdown voltage test of solid insulating materials, has computer control function, and the voltage rise rate can be adjusted between 10 V / s and 5 kV / s. Prepare circular epoxy resin specimens with a diameter of 25 mm and a thickness of 2 mm, ensuring that the specimen surface is flat. Clean the specimen surface to remove dust and impurities, ensuring that the surface has no defects. Turn on the power frequency high-voltage breakdown platform and warm up the machine to ensure that the instrument is in a stable state. Place the specimen between the test electrodes, ensuring good contact between the specimen and the electrodes. The entire electrode system needs to be placed in filtered transformer oil to prevent corona discharge from affecting the breakdown voltage value. Set the voltage rise rate to 1 kV / s in the instrument control software. Start the test, rotate the voltage booster to gradually increase the voltage until the specimen breaks down, and record the voltage value at the time of breakdown. Calculate the breakdown field strength (E) using the formula: E = U / d, where U is the breakdown voltage and d is the specimen thickness. Statistically analyze the test data of multiple specimens, and use the Weibull distribution model to analyze the breakdown data to obtain a more accurate withstand voltage strength. Calculate the self-healing efficiency by comparing the breakdown strength of the sample before and after the self-healing process. The formula is η = E1 / E2, where E1 is the breakdown strength of the epoxy resin after self-healing and E2 is the original breakdown strength of the epoxy resin without damage.

[0042] Example 1

[0043] This example provides a preparation method for a doped phase change microcapsule epoxy resin self-healing composite insulating material:

[0044] (1) Dissolve 1 g of Fe3O4 nanoparticles in 50 ml of absolute ethanol, and ultrasonically disperse for 30 min in an ultrasonic dispersion device with a frequency and power of 40 kHz and 200 W respectively to prepare dispersion solution 1;

[0045] Add 10 ml of concentrated ammonia water dropwise to 40 ml of dispersion solution 1 to obtain dispersion solution 2;

[0046] Add 5 ml of tetraethyl orthosilicate solution dropwise to 30 ml of dispersion solution 2 to obtain dispersion solution 3;

[0047] The dispersed solution 3 was placed in a water bath at 50 °C and stirred at a high speed of 1000 revolutions per minute for 8 h, followed by suction filtration. It was filtered and washed with methanol and deionized water respectively, and dried at room temperature to obtain Fe3O4@SiO2 nanoparticles.

[0048] (2) 2 g of Fe3O4@SiO2 nanoparticles were added to 100 ml of cetyltrimethylammonium bromide with a concentration of 0.06 mmol / L, and stirred at a high speed of 1200 revolutions per minute at room temperature for 2 h to obtain an aqueous solution;

[0049] 1 g of 500-nm silicon carbide particles were mixed with 20 g of octacosane, and stirred at a high speed of 1000 revolutions per minute in an oil bath at 120 °C for 30 min to obtain an oil phase solution;

[0050] (3) The prepared oil phase solution was mixed with the aqueous solution, and the addition ratio was 1.1:2.6. After the octacosane was solidified, it was filtered and washed with methanol and deionized water respectively, and dried at room temperature to obtain microcapsules;

[0051] (4) 90 parts of E51 type room temperature curing epoxy resin and 20 parts of 593 curing agent were mixed as the matrix; the microcapsules prepared in step (3) were mixed with the matrix, wherein the content of the microcapsules was 2 wt%. After the mixed sample was degassed, it was poured into a dumbbell-shaped polytetrafluoroethylene mold and cured at room temperature for 48 hours to obtain a doped phase change microcapsule epoxy self-healing composite insulating material.

[0052] Example 2

[0053] The difference from Example 1 was that the content of the two-component microcapsules in step (4) was 4 wt%, and the process of the remaining steps was referred to Example 1 to obtain the epoxy self-healing composite insulating material doped with phase change microcapsules in this example.

[0054] Example 3

[0055] The difference from Example 1 was that the content of the two-component microcapsules in step (4) was 6 wt%, and the process of the remaining steps was referred to Example 1 to obtain the epoxy self-healing composite insulating material doped with phase change microcapsules in this example.

[0056] Example 4

[0057] The difference from Example 1 was that the content of the two-component microcapsules in step (4) was 8 wt%, and the process of the remaining steps was referred to Example 1 to obtain the epoxy self-healing composite insulating material doped with phase change microcapsules in this example.

[0058] Comparative Example 1

[0059] The difference from Example 1 is that only a pure epoxy resin sample is prepared. The pure epoxy resin sample is obtained by mixing 90 parts of E51 type room temperature curing epoxy resin and 20 parts of 593 curing agent.

[0060] Comparative Example 2

[0061] The difference from Example 1 is that in step (1), the adjustment of using an ultrasonic dispersion device with 40 kHz and 200 W to ultrasonically disperse the nanoparticles for 30 min is to use a mechanical stirrer to stir the nanoparticles at a rate of 500 r / min for 30 min. The rest of the process steps refer to Example 1, and microcapsules with severe nanoparticle agglomeration and failed to form a coated shell are obtained in this comparative example.

[0062] Comparative Example 3

[0063] The difference from Example 1 is that in step (2), the adjustment of adding 2 g of Fe3O4@SiO2 nanoparticles to 100 ml of cetyltrimethylammonium bromide with a concentration of 0.06 mmol / L is to add 1 g of Fe3O4@SiO2 nanoparticles to 100 ml of cetyltrimethylammonium bromide with a concentration of 0.06 mmol / L. The rest of the process steps refer to Example 1, and microcapsules cannot be formed due to the imbalance between the shell material and the core material ratio in this comparative example.

[0064] Comparative Example 4

[0065] The difference from Example 1 is that in step (2), the adjustment of octacosane is docosane. The rest of the process steps refer to Example 1, and phase change microcapsules with a surface wrinkled morphology are obtained in this comparative example.

[0066] Comparative Example 5

[0067] The difference from Example 1 is that in step (2), the adjustment of 1 g of 500 nm silicon carbide particles is 1 g of 1 um carbon nanotubes. The rest of the process steps refer to Example 1, and carbon nanotube modified phase change microcapsules are obtained in this comparative example.

[0068] Comparative Example 6

[0069] The difference from Example 1 is that in step (2), the adjustment of 1 g of 500 nm silicon carbide particles is 1 g of 1 um boron nitride particles. The rest of the process steps refer to Example 1, and boron nitride particle modified phase change microcapsules are obtained in this comparative example.

[0070] Example 5

[0071] The samples prepared in Examples 1 - 4 and Comparative Example 1 were tested for thermal conductivity:

[0072] The thermal conductivity of the epoxy resin self - healing composite insulating material doped with phase change microcapsules varies with the content of microcapsules asFigure 2 As shown. The thermal conductivity value is the average of 6 measurements. The thermal conductivity of pure epoxy resin is 0.2063 W / m·K. The results show that as the microcapsule content increases from 0 wt% to 8 wt%, the thermal conductivity of the epoxy resin composite gradually increases to 0.3481 W / m·K. Compared with pure epoxy resin, the thermal conductivity of the self-healing epoxy resin composite has increased, probably because the microcapsules with Fe3O4@SiO2 nanoparticles as the shell crosslink with each other to form a heat conduction network chain, improving the thermal conductivity of the composite. The significance of the improved thermal conductivity can be explained from two aspects. On the one hand, the introduction of phase change microcapsules improves the thermal conductivity while maintaining good insulation performance of the composite, expanding the application environment of the epoxy resin self-healing composite insulation material. On the other hand, the increase in thermal conductivity also enables the epoxy resin self-healing composite insulation material to have the function of targeted heating. Octacosane can quickly melt and flow into the micro-damage channels, and when cooled to room temperature, octacosane solidifies to repair the damaged channels.

[0073] Example 6

[0074] The samples prepared in Examples 1 to 4 and Comparative Example 1 were tested for self-healing efficiency:

[0075] The self-healing efficiency of the samples was evaluated according to the fracture test of dumbbell-shaped samples.

[0076] The present invention uses phase change microcapsules with 500 nm silicon carbide particles and octacosane as the core and Fe3O4@SiO2 nanoparticles coated on the outer layer to prepare self-healing composites. The self-healing efficiency of dumbbell-shaped epoxy resin composites was measured using the same parameters to compare the self-healing efficiency of self-healing epoxy resin composite samples with different microcapsule contents. Figure 4 It is a bar chart of the tensile strength of epoxy resin composites with different microcapsule contents in the examples and comparative examples of the present invention.

[0077] Figure 5 It is a bar chart of the influence of different contents of repair agent microcapsules in the examples and comparative examples of the present invention on the self-healing efficiency of epoxy resin composites. According to Figure 5 It shows that as the microcapsule content increases from 2 wt% to 8 wt%, the self-healing efficiency of the epoxy resin composite increases significantly. When the content of the repair agent microcapsule is 8 wt%, the self-healing efficiency of the epoxy resin composite is 96.87%. Obviously, the self-healing effect is related to the amount of repair agent released by the ruptured microcapsules on the crack surface.

[0078] The relevant properties of the products prepared in each example and comparative example were measured, and the results are shown in Table 2.

[0079] Table 2

[0080]

[0081] It can be seen from Figure 1 that the microcapsules are relatively evenly distributed, most of them are spherical or approximately spherical, and the surface morphology is relatively smooth. The outer surface of the microcapsules is smooth and almost has no protrusions, which is due to the outer layer of the microcapsules being the Fe3O4@SiO2 nanoparticle shell. It can be seen from Table 2 that in Comparative Example 2 and Comparative Example 3, the microcapsules that failed to be successfully coated due to severe agglomeration and imbalance in the ratio of shell material to core material. From the examples, the rapid increase in this repair efficiency is due to the microcapsules releasing enough repair agent to fill the microcrack space. The phase change microcapsules embedded in the composite material system provide enough octacosane repair agent for the self-repair of epoxy resin composites and promote the bonding of the new epoxy resin with the original matrix interface.

[0082] 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 preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for preparing phase change microcapsules, characterized in that: including Dissolve Fe3O4 nanoparticles in absolute ethanol and ultrasonically disperse to obtain dispersion solution 1; add concentrated ammonia water to dispersion solution 1 to obtain dispersion solution 2; add tetraethyl orthosilicate to dispersion solution 2 to obtain dispersion solution 3; Mix and stir dispersion solution 3 under heating conditions, separate the solid and liquid, and filter and wash with methanol and deionized water respectively, and dry at room temperature to obtain Fe3O4@SiO2 nanoparticles; Dissolve Fe3O4@SiO2 nanoparticles in cetyltrimethylammonium bromide solution to obtain an aqueous solution; add silicon carbide particles to octacosane to obtain an oil phase solution; Stir the oil phase solution and the aqueous solution at room temperature to obtain an oil-water emulsion, filter and wash with methanol and deionized water respectively, and dry at room temperature to obtain the phase change microcapsules.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the Fe3O4 nanoparticles to the absolute ethanol is 1.0 - 1.1:35 - 40.

3. The preparation method according to claim 1, characterized in that: The mass ratio of dispersion solution 1 to concentrated ammonia water is 1.0 - 1.2:1.5 - 1.7; the mass ratio of tetraethyl orthosilicate to dispersion solution 2 is 1.0 - 1.1:42 - 45.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the aqueous solution to the oil phase solution is 18 - 22:12 - 15.

5. The preparation method according to claim 4, characterized in that: The mass ratio of Fe3O4@SiO2 nanoparticles to cetyltrimethylammonium bromide in the aqueous solution is 0.9 - 1.3:30 - 38.

6. The preparation method according to claim 4, characterized in that: The mass ratio of silicon carbide particles to octacosane in the oil phase solution is 1.1 - 1.4:30 - 34.

7. The phase change microcapsules prepared by the preparation method according to claims 1 to 6, characterized in that: The phase change microcapsules have a core-shell structure, wherein silicon carbide particles and octacosane are used as the core, and the outer layer is coated with Fe 3 O 4 @SiO 2 nanoparticles.

8. A preparation method of an epoxy resin self-healing composite insulating material doped with phase change microcapsules, characterized in that: including Use room temperature curable epoxy resin and curing agent as the matrix; mix the phase change microcapsules with the matrix, degas the mixed sample, and cure at room temperature to obtain the doped phase change microcapsule epoxy resin self-healing composite insulating material.

9. The preparation method according to claim 8, characterized in that: The mass ratio of the room temperature curable epoxy resin to the curing agent is 1.0 - 1.2:0.65 - 0.

85.

10. The preparation method according to claim 8, characterized in that: The total content of the phase change microcapsules is 2 - 8 wt%.

Images