High-performance insulating composite material and preparation method and application thereof

Abstract

The application provides a high-performance insulating composite material and a preparation method and application thereof, and belongs to the technical field of composite materials. The preparation method comprises the following steps: mixing an epoxy resin and a silane coupling agent solution to obtain a modified epoxy resin; mixing the modified epoxy resin and a curing agent to obtain an impregnation solution; performing thermal oxidation treatment on aramid fiber to obtain modified aramid fiber; performing ultrasonic impregnation on the modified aramid fiber in the impregnation solution to obtain aramid fiber prepreg; and performing layering and curing molding on the aramid fiber prepreg to obtain the high-performance insulating composite material. The preparation method provided by the application is simple in process, short in cycle and low in cost, the prepared composite material has high interlaminar shear strength and few internal defects, and is suitable for popularization and application in actual engineering.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, and specifically relates to a high-performance insulating composite material, its preparation method, and its application. Background Technology

[0002] Aramid fiber is a type of synthetic aromatic polyamide fiber. Para-aramid fiber (PPTA) has properties such as high specific strength, high modulus, high temperature resistance, corrosion resistance, low density and light weight, impact resistance, good dielectric properties and insulation, and is widely used in protective materials, lightweight structural materials and ultra-high voltage power grid transmission. However, PPTA has a typical "skin-core structure" with highly regular molecular chain segments, high orientation and high crystallinity. The presence of large conjugated benzene ring structure makes it difficult for amide groups to react with other groups. This results in a smooth surface, few active polar groups, low interfacial bonding force, poor wettability and difficulty in dispersion of para-aramid fiber, which limits the performance and application of para-aramid composite materials.

[0003] To address the issues of low surface activity, poor wettability, and poor dispersibility in para-aramid fibers, modification treatment is necessary. However, existing modification methods are often cumbersome, require large amounts of chemical reagents, pose certain operational risks, and are inefficient. Therefore, there is an urgent need for a simple, low-cost, and short-cycle modification method to improve the surface activity and wettability of para-aramid fibers, thereby enhancing the performance of para-aramid composite materials. Summary of the Invention

[0004] To address one or more technical problems existing in the prior art, this invention provides a high-performance insulating composite material, its preparation method, and its application. The preparation method provided by this invention is simple, has a short cycle, and is low in cost. The composite material obtained has high interlaminar shear strength and few defects, making it suitable for promotion and application in practical engineering.

[0005] The present invention provides a method for preparing a high-performance insulating composite material in a first aspect, the method comprising the following steps:

[0006] S1. Mix epoxy resin with a silane coupling agent solution to obtain modified epoxy resin;

[0007] S2. The modified epoxy resin is mixed with a curing agent to obtain an impregnation solution;

[0008] S3. The aramid fiber is subjected to thermal oxidation treatment to obtain modified aramid fiber;

[0009] S4. The modified aramid fiber is ultrasonically impregnated in the impregnation solution to obtain aramid fiber prepreg;

[0010] S5. Lay up and cure the aramid fiber prepreg to obtain the high-performance insulating composite material.

[0011] Preferably, in step S1, the coupling agent solution accounts for 2-3% of the mass of the modified epoxy resin; more preferably, the silane coupling agent accounts for 3-8% of the mass of the silane coupling agent solution, and more preferably 5%.

[0012] Preferably, in step S1, the silane coupling agent solution is obtained by mixing a silane coupling agent and a solvent;

[0013] Preferably, the solvent is a mixture of deionized water and anhydrous ethanol; more preferably, the mass ratio of deionized water to anhydrous ethanol in the solvent is 1:18.

[0014] Preferably, in step S2, the mass ratio of the modified epoxy resin to the curing agent is 100:(20-40), more preferably 100:30.

[0015] Preferably, the epoxy resin is E51 epoxy resin;

[0016] The silane coupling agent is KH550;

[0017] The curing agent is dicyandiamide; and / or

[0018] The aramid fiber is a para-aramid fiber, preferably an aramid III fiber.

[0019] Preferably, before step S3, a pretreatment step of the aramid fiber is further included;

[0020] The pretreatment is to remove the adhering substances on the surface of the aramid fiber; preferably, the aramid fiber is soaked in acetone for 6 hours, washed with distilled water, and then dried at 110°C for 4 hours.

[0021] Preferably, the ultrasonic impregnation time is 20–30 min; and / or

[0022] The thermal oxidation treatment is performed at a temperature of 500℃ for 3–5 minutes.

[0023] Preferably, the layup is performed by laying the aramid fiber prepreg in a mold using an alternating horizontal and vertical layup method; and / or

[0024] The curing temperature is 100–110°C.

[0025] In a second aspect, the present invention provides a high-performance insulating composite material, which is prepared by the preparation method described in the first aspect above.

[0026] The present invention provides, in a third aspect, the application of the high-performance insulating composite material described in the second aspect above in the field of ultra-high voltage power transmission.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] This invention, based on resin matrix modification, combines thermal oxidation modification and ultrasonic impregnation modification of aramid fibers to achieve the preparation of high-performance aramid fiber composite materials. Silane coupling agents can enhance the wettability and reactivity between the fiber and the resin matrix, forming a transitional interface layer between the fiber and the resin. Thermal oxidation treatment utilizes high temperatures to degrade or oxidize the surface of the aramid fibers, thereby destroying the dense, inert surface of the fibers and modifying them, effectively enhancing the shear strength of the composite material. Ultrasonic impregnation can solve the problem of difficult air removal within the aramid fiber prepreg laminate, eliminating bubble defects between the fiber and the resin matrix, thereby improving the strength of the material, product quality, and engineering applicability. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a microscopic CT image of the high-performance insulating composite material provided in the embodiments of the present invention;

[0031] Figure 2 This is a graph showing the relationship between the mass ratio of the silane coupling agent solution and epoxy resin in this invention and the interlaminar shear strength of the resin-modified composite material.

[0032] Figure 3 This is a graph showing the relationship between the ultrasonic impregnation time and the interlaminar shear strength of the ultrasonic-resin modified composite material of the present invention.

[0033] Figure 4 This is a graph showing the relationship between the thermal oxidation treatment time and the interlaminar shear strength of the ultrasonic-resin-modified-fiber-modified composite material of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] The present invention provides a method for preparing a high-performance insulating composite material in a first aspect, the method comprising the following steps:

[0036] S1. Mix epoxy resin with a silane coupling agent solution to obtain modified epoxy resin;

[0037] S2. The modified epoxy resin is mixed with a curing agent to obtain an impregnation solution;

[0038] S3. The aramid fiber is subjected to thermal oxidation treatment to obtain modified aramid fiber;

[0039] S4. The modified aramid fiber is ultrasonically impregnated in the impregnation solution to obtain aramid fiber prepreg;

[0040] S5. Lay up and cure the aramid fiber prepreg to obtain the high-performance insulating composite material.

[0041] This invention, based on resin matrix modification, combines thermal oxidation modification and ultrasonic impregnation modification of aramid fibers to achieve the preparation of high-performance aramid fiber composite materials. Silane coupling agents can enhance the wettability and reactivity between the fiber and the resin matrix, forming a transitional interface layer between the fiber and the resin. Thermal oxidation treatment utilizes high temperatures to degrade or oxidize the surface of the aramid fibers, thereby destroying the dense, inert surface of the fibers and modifying them, effectively enhancing the shear strength of the composite material. Ultrasonic impregnation can solve the problem of difficult air removal within the aramid fiber prepreg laminate, eliminating bubble defects between the fiber and the resin matrix, thereby improving the strength of the material, product quality, and engineering applicability.

[0042] The preparation method provided by this invention is simple, has a short cycle, low cost, does not require the addition of a large amount of chemical reagents, and is highly safe.

[0043] According to some preferred embodiments, in step S1, the coupling agent solution accounts for 2-3% of the mass of the modified epoxy resin (e.g., 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3%); preferably, the silane coupling agent accounts for 3-8% of the mass of the silane coupling agent solution (e.g., 3%, 4%, 5%, 6%, 7%, or 8%), and more preferably 5%.

[0044] This invention modifies epoxy resin with a silane coupling agent to enhance the wettability and reactivity of the fiber and the resin matrix. The coupling agent forms a transitional interface layer between the fiber and the resin, which improves the interfacial bonding strength of the aramid fiber and thus enhances the interlaminar shear strength.

[0045] To investigate the effect of silane coupling agent dosage on the interlaminar shear strength of composite materials and determine the optimal range of silane coupling agent dosage, this invention prepares composite materials by adjusting the mass ratio of epoxy resin and silane coupling agent solution, all other conditions being equal. The specific method is as follows: Epoxy resin is mixed with silane coupling agent solution to obtain modified epoxy resin; wherein, the silane coupling agent solution is obtained by mixing KH550 silane coupling agent and solvent; wherein, KH550 silane coupling agent accounts for 5% of the mass of the silane coupling agent solution; the modified epoxy resin is then subjected to temperature control at room temperature. Epoxy resin and dicyandiamide curing agent were mixed at a mass ratio of 100:30 and stirred thoroughly with a glass rod until the mixture was no longer viscous, thus obtaining an impregnation solution. Aramid III fibers were impregnated in the impregnation solution to obtain an aramid fiber prepreg. A release agent was applied to a mold, and the aramid fiber prepreg was laid up in a transverse and longitudinal layup pattern. Subsequently, a molding process was used to cure the resin-modified composite material at 100-110℃. The relationship between the mass ratio of silane coupling agent solution and epoxy resin and the shear strength between the layers of the resin-modified composite material is as follows: Figure 2 As shown, the interlaminar shear strength of resin-modified composite materials obtained when the mass ratio of epoxy resin to silane coupling agent solution is 98:2 (i.e., the silane coupling agent solution accounts for 2% of the mass of the modified epoxy resin) and 97:3 (i.e., the silane coupling agent solution accounts for 3% of the mass of the modified epoxy resin) is significantly improved compared with the composite material without silane coupling agent modification. Furthermore, the interlaminar shear strength of the resin-modified composite material is highest when the mass ratio of epoxy resin to silane coupling agent solution is 97:3. Therefore, this invention controls the amount of silane coupling agent solution within the above range to ensure that the silane coupling agent maximizes the wettability and reactivity between the fiber and the resin matrix, thereby enhancing the interlaminar shear strength of the composite material. If the amount of silane coupling agent is too large, it will affect the curing of the epoxy resin, weakening the cross-linking degree between the resins and leading to a decrease in the interlaminar shear strength of the sample. If the amount of silane coupling agent is too small, the modification effect is poor, and the improvement in the wettability and reactivity between the fiber and the resin matrix is ​​not significant.

[0046] According to some preferred embodiments, in step S1, the silane coupling agent solution is obtained by mixing a silane coupling agent and a solvent;

[0047] Preferably, the solvent is a mixture of deionized water and anhydrous ethanol.

[0048] In some more preferred embodiments, the mass ratio of deionized water to anhydrous ethanol in the solvent is 1:18.

[0049] According to some preferred embodiments, in step S2, the mass ratio of the modified epoxy resin to the curing agent is 100:(20-40) (for example, it can be 100:20, 100:25, 100:30, 100:35 or 100:40), preferably 100:30.

[0050] According to some preferred embodiments, the epoxy resin is E51 epoxy resin;

[0051] The silane coupling agent is KH550;

[0052] The curing agent is dicyandiamide; and / or

[0053] The aramid fiber is a para-aramid fiber, preferably an aramid III fiber.

[0054] According to some preferred embodiments, before step S3, a step of pretreating the aramid fiber is also included;

[0055] The pretreatment is to remove the adhering substances on the surface of the aramid fiber; preferably, the aramid fiber is soaked in acetone for 6 hours, washed with distilled water, and then dried at 110°C for 4 hours.

[0056] According to some preferred embodiments, the ultrasonic impregnation time is 20 to 30 minutes (for example, it can be 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes or 30 minutes).

[0057] This invention uses ultrasonic impregnation to remove gas adhering to the fiber surface, thereby increasing the degree of impregnation on the aramid fiber surface and achieving full impregnation of the fiber and resin. It coats the surface of the inert fiber with a layer of active resin "coat", eliminating bubble defects between the aramid fiber and the resin matrix, enhancing the fiber surface activity, and thus improving the interlaminar shear strength of the material.

[0058] To investigate the effect of ultrasonic impregnation time on the interlaminar shear strength of composite materials and determine the optimal treatment time range for ultrasonic impregnation, this invention prepared different composite materials by adjusting the ultrasonic impregnation time under the same conditions. The specific method is as follows: Epoxy resin and silane coupling agent solution were mixed at a mass ratio of 97:3 to obtain modified epoxy resin; wherein, the silane coupling agent solution was obtained by mixing KH550 silane coupling agent and solvent, and KH550 silane coupling agent accounted for 5% of the mass of the silane coupling agent solution; under room temperature conditions... Modified epoxy resin and dicyandiamide curing agent were mixed at a mass ratio of 100:30 and stirred thoroughly with a glass rod until the mixture was no longer viscous, thus obtaining an impregnation solution. Aramid fibers were ultrasonically impregnated in the impregnation solution to obtain an aramid fiber prepreg. A release agent was applied to a mold, and the aramid III fiber prepreg was laid up in a transverse and longitudinal layup pattern. Subsequently, it was cured using a molding process at 100-110℃ to obtain an ultrasonic-resin modified composite material. The relationship between the ultrasonic impregnation time and the interlaminar shear strength of the ultrasonic-resin modified composite material is as follows: Figure 3 As shown, the interlaminar shear strength of the ultrasonic-resin modified composite material obtained in 20-30 minutes is relatively high, which is significantly improved compared with the interlaminar shear strength of the composite material without ultrasonic treatment. Therefore, the present invention can obtain a composite material with high shear strength by controlling the ultrasonic impregnation time within the above range. The interlaminar shear strength gradually stabilizes with the extension of time because the surface wettability of the fiber and the resin matrix does not change during the ultrasonic impregnation process, the adhesion between the fiber and the resin matrix is ​​very small, and after the gas attached between the fibers is completely discharged, the interlaminar shear strength does not change significantly with the extension of ultrasonic treatment time.

[0059] According to some preferred embodiments, the temperature of the thermal oxidation treatment is 500°C and the time is 3 to 5 minutes (for example, it can be 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes or 5 minutes).

[0060] This invention modifies aramid fibers by thermally oxidizing them to etch the surface of the fibers, thereby destroying the dense, inert surface of the fibers and effectively improving the shear strength of the composite material.

[0061] Based on the thermogravimetric curve of aramid III fiber, this invention determines the thermal oxidation treatment temperature to be 500℃. To further investigate the effect of thermal oxidation treatment time on the interlaminar shear strength of the composite material and determine the optimal treatment time range, this invention prepares different composite materials by adjusting the thermal oxidation treatment time under the same conditions. The specific method is as follows: Epoxy resin and silane coupling agent solution are mixed at a mass ratio of 97:3 to obtain modified epoxy resin; wherein, the silane coupling agent solution is obtained by mixing KH550 silane coupling agent and solvent, with KH550 silane coupling agent accounting for 5% of the silane coupling agent solution mass; the modified epoxy resin is then reacted with dicyandiamide at room temperature. The chemical agents were mixed at a mass ratio of 100:30 and stirred thoroughly with a glass rod until the mixture was no longer viscous, thus obtaining the impregnation solution. Aramid III fibers were placed in a heating furnace and subjected to thermal oxidation treatment at 500℃ to fully oxidize the fiber surface, obtaining modified aramid fibers. The modified aramid fibers were ultrasonically impregnated in the impregnation solution for 20 minutes to obtain aramid fiber prepreg. A release agent was applied to a mold, and the aramid fiber prepreg was laid up in a transverse and longitudinal layup pattern. Subsequently, it was cured using a molding process at 100-110℃ to obtain an ultrasonic-resin-modified-fiber-modified composite material. The relationship between the thermal oxidation treatment time and the interlaminar shear strength of the ultrasonic-resin-modified-fiber-modified composite material is as follows: Figure 4 As shown, the ultrasonic-resin-modified-fiber-modified composite material obtained with a thermal oxidation treatment time of 3-5 minutes exhibits a higher interlaminar shear strength, reaching its maximum value at 4 minutes, and showing a significant improvement in interlaminar shear strength compared to the composite material without thermal oxidation treatment. Therefore, this invention controls the thermal oxidation treatment time within the above range to ensure the etching effect on the aramid fiber surface, thereby enhancing the interlaminar shear strength of the composite material. If the thermal oxidation treatment time is too long, the strong etching effect on the fiber surface will cause the etching effect to no longer be concentrated on the fiber surface, damaging the fiber body and thus reducing the interlaminar shear strength of the composite material. If the thermal oxidation treatment time is too short, the etching effect on the fiber surface is poor and cannot effectively improve the interlaminar shear strength of the composite material.

[0062] According to some preferred embodiments, the layup is performed by alternating horizontal and vertical layup of the aramid fiber prepreg in the mold; the aramid fiber prepreg of the present invention is laid in the mold using an alternating horizontal and vertical layup method (i.e., alternating horizontal and vertical layups), ultimately forming an alternating arrangement of horizontal and vertical layups; the alternating horizontal and vertical layup method of the present invention can effectively improve the resin wettability, resulting in a composite material with more uniform structure and properties; the present invention does not specifically limit the shape of the mold and the number of layups, and the mold can be cylindrical, square, or other shapes; the specific shape of the mold and the number of layups can be selected and designed according to the actual application scenario. and / or

[0063] The curing temperature is 100-110℃ (for example, it can be 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃ or 110℃).

[0064] In a second aspect, the present invention provides a high-performance insulating composite material, which is prepared by the preparation method described in the first aspect above.

[0065] The present invention provides, in a third aspect, the application of the high-performance insulating composite material described in the second aspect above in the field of ultra-high voltage power transmission.

[0066] The high-performance insulating composite material provided by this invention has high interlaminar shear strength and few defects, making it suitable for promotion and application in actual engineering projects in the field of ultra-high voltage power transmission.

[0067] To more clearly illustrate the technical solution and advantages of the present invention, the present invention will be further described below in conjunction with embodiments.

[0068] The materials and reagents used in this invention can be purchased directly from the market or synthesized in-house, and there are no restrictions on the specific models.

[0069] The performance testing of the composite materials in the embodiments and comparative examples of this invention is performed using the following methods:

[0070] Interlaminar shear strength test: Interlaminar shear strength test was carried out using an electronic universal testing machine (model: TSE503A, Shanghai Wan Test Testing Machine Co., Ltd.).

[0071] The interlaminar shear strength (ILSS) of the composite materials in the examples and comparative examples was tested using the three-point short beam bending method according to ASTM D 2344 on a universal testing machine. The test temperature and relative humidity conditions were 20°C and 50%, respectively. The specimen size was 25mm × 6mm × 2mm, with a span-to-thickness ratio of 5:1. The indenter loading speed was 2mm / min. Five specimens were tested in each group, and the average value was taken. The formula for calculating the ILSS value of the composite material is as follows:

[0072]

[0073] Where τ is the ILSS value of the composite material, in MPa; P b 1 is the maximum load the specimen can withstand at the time of failure, in N; b is the specimen width, in mm; h is the specimen thickness, in mm.

[0074] Defect quantity detection: The number of defects was detected using an EPOCH 650 ultrasonic flaw detector, measuring the number of defects with a size of 1 to 200 μm.

[0075] Example 1

[0076] S1. Mix 582g of E51 epoxy resin with 18g of KH550 silane coupling agent solution to obtain modified epoxy resin; wherein, the silane coupling agent solution is obtained by mixing 1g of KH550 silane coupling agent, 1g of deionized water and 18g of anhydrous ethanol and then stirring thoroughly in a centrifuge at room temperature for 10min.

[0077] S2. Mix 600g of modified epoxy resin with 180g of dicyandiamide curing agent at room temperature, and stir thoroughly with a glass rod until the mixture is no longer viscous to obtain the impregnation solution.

[0078] S3. Place the aramid III fiber in a heating furnace and perform thermal oxidation treatment at 500℃ for 4 minutes to fully oxidize the fiber surface and obtain modified aramid fiber;

[0079] S4. The modified aramid fiber is ultrasonically impregnated in the impregnation solution for 20 minutes to obtain aramid fiber prepreg;

[0080] S5. Apply a release agent to the mold, lay up the aramid fiber prepreg in a transverse and longitudinal layup manner, and then use a molding process to cure and form the composite material at 100-110℃.

[0081] The composite material prepared in Example 1 has an interlaminar shear strength of 59.35 MPa and an internal defect number of 11.

[0082] Depend on Figure 1 It can be seen that the aramid fibers in the composite material have good wettability with the resin matrix and no structural defects.

[0083] Comparative Example 1

[0084] S1. Mix 582g of epoxy resin with 180g of dicyandiamide curing agent, and stir thoroughly with a glass rod until the mixture is no longer viscous to obtain the impregnation liquid;

[0085] S2. Immerse aramid III fibers in the impregnation solution for 20 minutes to obtain aramid fiber prepreg;

[0086] S3. Apply a release agent to the mold, lay up the aramid fiber prepreg in a transverse and longitudinal layup manner, and then use a molding process to cure and form the composite material at 100-110℃.

[0087] The composite material prepared in Comparative Example 1 has an interlaminar shear strength of 33.65 MPa and an internal defect number of 51.

[0088] Comparative Example 2

[0089] S1. Mix 582g of E51 epoxy resin with 18g of KH550 silane coupling agent solution to obtain modified epoxy resin; wherein, the silane coupling agent solution is obtained by mixing 1g of KH550 silane coupling agent, 1g of deionized water and 18g of anhydrous ethanol and then stirring thoroughly in a centrifuge at room temperature for 10min.

[0090] S2. Mix 600g of modified epoxy resin with 180g of dicyandiamide curing agent at room temperature, and stir thoroughly with a glass rod until the mixture is no longer viscous to obtain the impregnation solution.

[0091] S3. Immerse aramid III fibers in the impregnation solution for 20 minutes to obtain aramid fiber prepreg;

[0092] S4. Apply a release agent to the mold, lay up the aramid fiber prepreg in a transverse and longitudinal layup manner, and then use a molding process to cure and form the composite material at 100-110℃.

[0093] The composite material prepared in Comparative Example 2 has an interlaminar shear strength of 41.3 MPa and an internal defect number of 26.

[0094] Comparative Example 3

[0095] S1. Mix 582g of E51 epoxy resin with 18g of KH550 silane coupling agent solution to obtain modified epoxy resin; wherein, the silane coupling agent solution is obtained by mixing 1g of KH550 silane coupling agent, 1g of deionized water and 18g of anhydrous ethanol and then stirring thoroughly in a centrifuge at room temperature for 10min.

[0096] S2. Mix 600g of modified epoxy resin with 180g of dicyandiamide curing agent at room temperature, and stir thoroughly with a glass rod until the mixture is no longer viscous to obtain the impregnation solution.

[0097] S3. Aramid III fibers are ultrasonically impregnated in impregnation solution for 20 min to obtain aramid fiber prepreg;

[0098] S4. Apply a release agent to the mold, lay up the aramid fiber prepreg in a transverse and longitudinal layup manner, and then use a molding process to cure and form the composite material at 100-110℃.

[0099] The composite material prepared in Comparative Example 3 had an interlaminar shear strength of 46.85 MPa and an internal defect number of 18.

[0100] Comparative Example 4

[0101] S1. Mix 582g of E51 epoxy resin with 18g of KH550 silane coupling agent solution to obtain modified epoxy resin; wherein, the silane coupling agent solution is obtained by mixing 1g of KH550 silane coupling agent, 1g of deionized water and 18g of anhydrous ethanol and then stirring thoroughly in a centrifuge at room temperature for 10min.

[0102] S2. Mix 600g of modified epoxy resin with 180g of dicyandiamide curing agent at room temperature, and stir thoroughly with a glass rod until the mixture is no longer viscous to obtain the impregnation solution.

[0103] S3. Place the aramid III fiber in a heating furnace and perform thermal oxidation treatment at 500℃ for 2 minutes to fully oxidize the fiber surface and obtain modified aramid fiber;

[0104] S4. The modified aramid fiber is ultrasonically impregnated in the impregnation solution for 20 minutes to obtain aramid fiber prepreg;

[0105] S5. Apply a release agent to the mold, lay up the aramid fiber prepreg in a transverse and longitudinal layup manner, and then use a molding process to cure and form the composite material at 100-110℃.

[0106] The interlaminar shear strength of the composite material prepared in Comparative Example 4 was 53.12 MPa.

[0107] Comparative Example 5

[0108] S1. Mix 582g of E51 epoxy resin with 18g of KH550 silane coupling agent solution to obtain modified epoxy resin; wherein, the silane coupling agent solution is obtained by mixing 1g of KH550 silane coupling agent, 1g of deionized water and 18g of anhydrous ethanol and then stirring thoroughly in a centrifuge at room temperature for 10min.

[0109] S2. Mix 600g of modified epoxy resin with 180g of dicyandiamide curing agent at room temperature, and stir thoroughly with a glass rod until the mixture is no longer viscous to obtain the impregnation solution.

[0110] S3. Place the aramid III fiber in a heating furnace and perform thermal oxidation treatment at 500℃ for 8 minutes to fully oxidize the fiber surface and obtain modified aramid fiber;

[0111] S4. The modified aramid fiber is ultrasonically impregnated in the impregnation solution for 20 minutes to obtain aramid fiber prepreg;

[0112] S5. Apply a release agent to the mold, lay up the aramid fiber prepreg in a transverse and longitudinal layup manner, and then use a molding process to cure and form the composite material at 100-110℃.

[0113] The interlaminar shear strength of the composite material prepared in Comparative Example 5 was 47.68 MPa.

[0114] In summary, the embodiments of the present invention, based on the modification of the resin matrix, combined with the thermal oxidation modification of aramid fibers and ultrasonic impregnation modification methods, can effectively improve the interlaminar shear strength of the composite material and reduce the number of internal defects in the composite material. The resulting composite material can be promoted and applied in actual engineering projects in the field of ultra-high voltage power transmission.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-performance insulating composite material, characterized in that, The preparation method includes the following steps: S1. Epoxy resin is mixed with a silane coupling agent solution to obtain a modified epoxy resin; the coupling agent solution accounts for 2-3% of the mass of the modified epoxy resin; the silane coupling agent accounts for 5% of the mass of the silane coupling agent solution. S2. The modified epoxy resin is mixed with a curing agent to obtain an impregnation solution; the epoxy resin is E51 epoxy resin; the silane coupling agent is KH550; and the curing agent is dicyandiamide. S3. The aramid fiber is subjected to thermal oxidation treatment to obtain modified aramid fiber; the thermal oxidation treatment temperature is 500℃ and the time is 3~5min; the aramid fiber is para-aramid fiber; S4. The modified aramid fiber is ultrasonically impregnated in the impregnation solution to obtain aramid fiber prepreg; the ultrasonic impregnation time is 20-30 minutes. S5. Lay up and cure the aramid fiber prepreg to obtain the high-performance insulating composite material; the layup is carried out by laying the aramid fiber prepreg in the mold using an alternating horizontal and vertical layup method.

2. The preparation method according to claim 1, characterized in that, In step S1, the silane coupling agent solution is obtained by mixing a silane coupling agent and a solvent; the solvent is a mixture of deionized water and anhydrous ethanol.

3. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of the modified epoxy resin to the curing agent is 100:(20~40).

4. The preparation method according to claim 3, characterized in that, The mass ratio of the modified epoxy resin to the curing agent is 100:

30.

5. The preparation method according to claim 1, characterized in that, The aramid fiber is aramid III fiber.

6. The preparation method according to claim 1, characterized in that, Before step S3, a pretreatment step for the aramid fiber is also included; The pretreatment involves removing the surface deposits of the aramid fibers; the aramid fibers are soaked in acetone for 6 hours, washed with distilled water, and then dried at 110°C for 4 hours.

7. The preparation method according to claim 1, characterized in that, The curing temperature is 100~110℃.

8. A high-performance insulating composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The application of the high-performance insulating composite material according to claim 8 in the field of ultra-high voltage power transmission.

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