A bagasse-based carbon fiber and epoxy resin composite material for composite insulating cross arm and a preparation method thereof

Abstract

This invention discloses a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms and its preparation method, belonging to the field of composite material processing technology. The composite material uses bagasse-based carbon fiber as the reinforcing phase and epoxy resin as the matrix, and incorporates inorganic insulating fillers, flame retardants, and anti-aging additives. The bagasse-based carbon fiber is prepared by mixing bagasse with the resin system after bagasse drying pretreatment, inert atmosphere carbonization, and surface modification. The mixture is then molded, cured in stages, and treated with a surface insulating coating. The resulting composite insulating crossarm exhibits high flexural strength, high volume resistivity, and low water absorption, possessing excellent mechanical properties, electrical insulation properties, and environmental adaptability. It is suitable for power transmission and distribution lines and power engineering projects in complex environments, and has broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of composite material processing technology, specifically to a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms and its preparation method. Background Technology

[0002] Against the backdrop of the global power transmission system developing towards high reliability, lightweight design, and full-cycle cost optimization, high-performance composite material insulated crossarms have become a rigid requirement for laying in harsh environments such as coastal areas, chemical industrial parks, new energy power plants, and urban underground utility tunnels. Their performance is directly related to power grid safety and long-term operational benefits.

[0003] Composite material insulated crossarms possess excellent electrical and mechanical properties, effectively replacing traditional iron crossarms. Composite materials are novel materials formed by combining two or more materials, retaining the advantages of each while acquiring properties not possessed by the constituent materials. Fiber-reinforced composite materials mainly consist of a resin matrix and fibers, exhibiting good chemical stability, excellent electrical properties, and corrosion resistance. Currently, the resin material for fiber-reinforced composite insulated crossarms used in domestic power equipment is mainly epoxy, and the fibers are mainly glass fiber and basalt fiber. Glass fiber composite insulated crossarms possess excellent mechanical and electrical insulation properties, but their aging resistance is insufficient. Since the modulus of glass fiber is also relatively low compared to basalt fiber, the modulus of the corresponding composite products is low. Therefore, basalt fiber is currently a better alternative to glass fiber, but it still has shortcomings in terms of economy and sustainability. Furthermore, because composite insulated crossarms operate outdoors for extended periods, they are subjected to erosion under harsh climatic conditions such as sun exposure, rain, wind, sandstorms, high temperatures, and extreme cold. Therefore, there is a need to develop a lower-cost composite material that can be used under complex environmental conditions such as high loads, high humidity, salt spray, and corrosive environments.

[0004] Bagasse-based carbon fiber is prepared from bagasse, a resource that is abundant and inexpensive. By carbonizing and reusing industrial waste, not only are material costs reduced, but the burden of waste disposal is also lessened. As a fiber-reinforced composite material, it has significant advantages in terms of economy and sustainability. Currently, research on the application of bagasse-based carbon fiber in electrical insulation crossarms is still limited, especially regarding the balance between mechanical and electrical insulation properties; systematic research and engineering application reports are lacking. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms and its preparation method. The composite insulating crossarm possesses excellent mechanical properties, excellent electrical insulation properties, and good environmental adaptability.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms, comprising the following components by weight: 25-35 parts bagasse-based carbon fiber, 38-50 parts epoxy resin, 10-13 parts curing agent, 0.2-0.5 parts curing accelerator, 10-15 parts inorganic insulating filler, 2-4 parts flame retardant, and 0.5-0.8 parts anti-aging additive.

[0007] Furthermore, the inorganic insulating filler is one or both of silicon dioxide and aluminum oxide.

[0008] Furthermore, the flame retardant is a mixture of aluminum hydroxide and an organophosphorus flame retardant in a mass ratio of 2:1.

[0009] Furthermore, the anti-aging additive is a mixture of hindered phenolic antioxidant and ultraviolet light absorber in a mass ratio of 1:1.

[0010] A method for preparing a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms includes the following preparation steps:

[0011] Step S1: Bagasse drying pretreatment

[0012] After selecting bagasse and screening and washing, it is dried at 100-110 ℃ for 10-14 h to remove free moisture.

[0013] Step S2: Inert atmosphere carbonization

[0014] The dried bagasse is placed in an inert atmosphere furnace and heated to 600-800℃ at a heating rate of 3-5℃ / min. After holding at this temperature for 1-2 hours, it is naturally cooled to obtain bagasse-based carbon fiber.

[0015] Step S3: Surface Modification

[0016] The bagasse-based carbon fiber obtained in step S2 is placed in a silane coupling agent solution for surface modification treatment to obtain surface-modified bagasse-based carbon fiber.

[0017] Step S4: Resin system preparation

[0018] Weigh out epoxy resin, curing agent, curing accelerator, inorganic insulating filler, flame retardant and anti-aging additive in proportion, mix and stir evenly, and degas under vacuum to obtain a resin system mixture.

[0019] Step S5: Compression molding

[0020] After mixing the surface-modified bagasse-based carbon fiber with the resin system mixture of step S4 in a certain proportion, the mixture is placed in a mold and molded to prepare the crossbeam blank.

[0021] Step S6: Staged curing

[0022] The molded crossbeam blank is subjected to a staged curing process;

[0023] Step S7: Surface Insulating Coating Treatment

[0024] The cured crossarm is machined to meet assembly requirements, and an insulating coating is applied to its surface by spraying or dipping.

[0025] Furthermore, in step S2, the inert atmosphere of the inert atmosphere furnace is nitrogen or argon.

[0026] Furthermore, in step S3, the silane coupling agent solution is an aqueous solution of aminopropylsilane coupling agent in ethanol with a mass fraction of 1-3%, wherein the volume ratio of ethanol to deionized water is 90:10-95:5, and the pH of the solution is 4-5.

[0027] Furthermore, in step S5, the molding temperature is 110-130℃, the molding pressure is 5-8MPa, and the holding time is 30-40min.

[0028] Furthermore, in step S6, the staged curing process includes a pre-curing stage, a main curing stage, and a post-curing stage. The temperature of the pre-curing stage is 70-90℃, and the holding time is 0.5-1.5h. The curing temperature of the main curing stage is 110-130℃, and the holding time is 1-3h. The curing temperature of the post-curing stage is 140-160℃, and the holding time is 1-3h.

[0029] Furthermore, in step S7, the insulating coating is silicone rubber or a highly insulating epoxy material, and the coating thickness is 0.5-1.0 mm.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) Through reasonable process parameter settings and synergistic effects between various processes, the present invention enables the reinforcing fibers to be uniformly distributed in the matrix and form a stable interface structure. The resulting composite material insulation crossarm has a bending strength ≥205MPa and a volume resistivity >1×10⁻⁶. 12 With a water absorption rate of <0.5% and excellent mechanical properties, it also possesses excellent electrical insulation properties and good environmental adaptability.

[0032] (2) The bagasse-based carbon fiber of the present invention is obtained by bagasse carbonization and surface modification treatment. Bagasse raw material resources are abundant and low cost. As a fiber-reinforced composite material, it has obvious advantages in terms of economy and sustainability. After carbonization, bagasse forms a carbon fiber skeleton with a porous structure. After modification with silane coupling agent, active groups are introduced to improve its interfacial bonding ability with epoxy resin matrix. At the same time, inorganic insulating filler is added to the system to block the conductive path and inhibit the formation of conductive network between carbon fibers. Combined with the staged curing process, the resin crosslinking uniformity is improved and the internal stress is reduced, thereby significantly improving the electrical insulation performance and environmental stability of the composite material while ensuring mechanical properties.

[0033] (3) By coating the surface with an insulating coating, the present invention further improves the insulation barrier, effectively suppresses moisture penetration, electro-tracking and surface discharge phenomena, and enables the composite material insulating crossarm to maintain stable performance during long-term service in high humidity, salt spray and corrosive environments. Attached Figure Description

[0034] Figure 1 This is a SEM image of bagasse carbonized in Example 1 of the present invention;

[0035] Figure 2 This is a comparison diagram of the bending strength of the composite insulating crossarms prepared in Examples 1-4 and Comparative Examples 1-8 of the present invention;

[0036] Figure 3 This is a comparison diagram of the volume resistivity of the composite material insulating crossarms prepared in Examples 1-4 and Comparative Examples 1-8 of the present invention.

[0037] Figure 4 This is a comparison chart of the water absorption rates of the composite insulating crossarms prepared in Examples 1-4 and Comparative Examples 1-8 of the present invention. Detailed Implementation

[0038] The specific embodiments of the present invention will be further described below with reference to examples.

[0039] Example 1

[0040] A bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms, comprising the following components by weight: 30 parts bagasse-based carbon fiber, 44.3 parts epoxy resin, 11.76 parts curing agent, 0.44 parts curing accelerator, 10 parts inorganic insulating filler, 2.9 parts flame retardant, and 0.7 parts anti-aging additive.

[0041] The epoxy resin is bisphenol A epoxy resin with an epoxy value of 0.48–0.54; the curing agent is methyltetrahydrophthalic anhydride; the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol; the inorganic insulating filler is a mixture of silica and alumina in a 1:1 mass ratio; the flame retardant is a mixture of aluminum hydroxide and phenylphosphoric acid in a 2:1 mass ratio; and the anti-aging additive is a mixture of antioxidant 1010 and ultraviolet absorber 328 in a 1:1 mass ratio.

[0042] A method for preparing a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms, the specific preparation steps are as follows:

[0043] Step S1: Bagasse drying pretreatment

[0044] Sugarcane bagasse, a byproduct of the sugar industry, was selected, screened, and washed, and then dried at 105℃ for 12 hours to remove free moisture.

[0045] Step S2: Inert atmosphere carbonization

[0046] The dried bagasse was placed in a nitrogen atmosphere furnace and heated to 650°C at a heating rate of 5°C / min. After holding at this temperature for 2 hours, it was naturally cooled to obtain bagasse-based carbon fiber.

[0047] Step S3: Surface Modification

[0048] The bagasse-based carbon fiber obtained in step S2 was placed in an aqueous solution of 1% (w / w) aminopropyltriethoxysilane coupling agent ethanol for surface modification treatment to improve its surface activity and interfacial bonding performance with the epoxy resin matrix. The volume ratio of ethanol to deionized water in the aqueous solution was 90:10, and the pH of the solution was 4.

[0049] Step S4: Resin system preparation

[0050] Weigh the epoxy resin, curing agent, curing accelerator, inorganic insulating filler, flame retardant and anti-aging additive according to the mass ratio, mix and stir evenly, and degas under vacuum to obtain a resin system mixture.

[0051] Step S5: Compression molding

[0052] The surface-modified bagasse-based carbon fiber and the resin system mixture obtained in step S4 were mixed in proportion and molded into a mold to prepare the crossbeam blank.

[0053] Step S6: Staged curing

[0054] The compression-molded crossbeam blank is subjected to a staged curing process: first, it is pre-cured at 80℃ for 1 hour, then mainly cured at 120℃ for 2 hours, and finally cured at 150℃ for 2 hours to obtain a stable and dense composite material structure.

[0055] Step S7: Surface Insulating Coating Treatment

[0056] The cured crossarm is machined to meet assembly requirements, and a silicone rubber insulating coating with a thickness of 1.0 mm is applied to its surface via dip coating. The machining process includes cutting, drilling, milling, and surface polishing. Specifically, a saw blade is first used to cut the crossarm to a fixed length to achieve the designed dimensions; then, the end face is milled to ensure flatness; next, mounting holes are drilled at predetermined locations; finally, the machined surface is polished to remove burrs.

[0057] Scanning electron microscopy (SEM) was performed on the carbonized bagasse from Example 1 to observe its surface morphology and microstructure. Specifically, the carbonized bagasse sample was fixed on a conductive adhesive, sputtered with gold, and the surface morphology of the sample was observed under the conditions of accelerating voltage EHT 5.00kV and working distance WD 7.3 mm. Figure 1 The image shown is a SEM image of bagasse carbonized in Example 1. The SEM image shows that the surface of the carbonized bagasse is rough, maintaining the skeletal structure of the fibers.

[0058] Example 2

[0059] This embodiment aims to investigate the effect of carbonization temperature on the properties of composite materials. Compared with Example 1, the preparation process parameters are exactly the same except for the carbonization temperature in step S2.

[0060] Step S2: Inert atmosphere carbonization

[0061] The dried bagasse was placed in a nitrogen atmosphere furnace and heated to 600°C at a heating rate of 5°C / min. After holding at this temperature for 2 hours, it was naturally cooled to obtain bagasse-based carbon fiber.

[0062] Example 3

[0063] This embodiment aims to investigate the effect of carbonization temperature on the properties of composite materials. Compared with Example 1, the preparation process parameters are exactly the same except for the carbonization temperature in step S2.

[0064] Step S2: Inert atmosphere carbonization

[0065] The dried bagasse was placed in a nitrogen atmosphere furnace and heated to 700°C at a heating rate of 5°C / min. After holding at this temperature for 2 hours, it was naturally cooled to obtain bagasse-based carbon fiber.

[0066] Example 4

[0067] This embodiment aims to examine the effect of fiber content on the properties of the composite material. Compared with Example 1, the preparation process parameters are exactly the same except for the different amounts of composite material components.

[0068] A bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms comprises the following components by weight: 35 parts bagasse-based carbon fiber, 39.3 parts epoxy resin, 11.81 parts curing agent, 0.39 parts curing accelerator, 10 parts inorganic insulating filler, 2.9 parts flame retardant, and 0.7 parts anti-aging additive.

[0069] Comparative Example 1

[0070] This comparative example aims to examine the effect of carbonization on the properties of composite materials. Compared with Example 1, bagasse was not subjected to the inert atmosphere carbonization treatment in step S2.

[0071] By weight, the composite material comprises the following components: 30 parts bagasse fiber, 44.3 parts epoxy resin, 11.76 parts curing agent, 0.44 parts curing accelerator, 10 parts inorganic insulating filler, 2.9 parts flame retardant, and 0.7 parts anti-aging additive.

[0072] The epoxy resin is bisphenol A epoxy resin with an epoxy value of 0.48–0.54; the curing agent is methyltetrahydrophthalic anhydride; the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol; the inorganic insulating filler is a mixture of silica and alumina in a 1:1 mass ratio; the flame retardant is a mixture of aluminum hydroxide and phenylphosphoric acid in a 2:1 mass ratio; and the anti-aging additive is a mixture of antioxidant 1010 and ultraviolet absorber 328 in a 1:1 mass ratio.

[0073] The preparation steps of this composite material are as follows:

[0074] Step S1: Bagasse drying pretreatment

[0075] Sugarcane bagasse, a byproduct of the sugar industry, was selected, screened, and washed, and then dried at 105℃ for 12 hours to remove free moisture.

[0076] Step S2: Surface Modification

[0077] The bagasse obtained in step S1 was placed in a 1% (w / w) aqueous solution of aminopropyltriethoxysilane coupling agent ethanol for surface modification treatment to improve its surface activity and interfacial bonding performance with the epoxy resin matrix. The volume ratio of ethanol to deionized water in the aqueous solution was 90:10, and the pH of the solution was 4.

[0078] Step S3: Resin system preparation

[0079] Weigh out epoxy resin, curing agent, curing accelerator, inorganic insulating filler, flame retardant and anti-aging additive in proportion, mix and stir evenly, and degas under vacuum to obtain a resin system mixture.

[0080] Step S4: Compression molding

[0081] The surface-modified bagasse fiber and the resin system mixture obtained in step S3 are mixed in proportion and placed in a mold for compression molding to prepare the crossbeam blank. The compression molding temperature is 120℃, the molding pressure is 6 MPa, and the holding time is 30 min.

[0082] Step S5: Staged curing

[0083] The molded crossbeam blank is subjected to a staged curing process: first, pre-curing at 80℃ for 1 hour, then main curing at 120℃ for 2 hours, and finally post-curing at 150℃ for 2 hours to obtain a stable and dense composite material structure.

[0084] Step S6: Surface Insulating Coating Treatment

[0085] The cured crossarm is machined to meet assembly requirements, and a silicone rubber insulating coating with a thickness of 1.0 mm is applied to its surface via dip coating. The machining process includes cutting, drilling, milling, and surface polishing. Specifically, a saw blade is first used to cut the crossarm to a fixed length to achieve the designed dimensions; then, the end face is milled to ensure flatness; next, mounting holes are drilled at predetermined locations; finally, the machined surface is polished to remove burrs.

[0086] Comparative Example 2

[0087] This comparative example aims to examine the effect of carbonization temperature on the properties of the composite material. Compared with Example 1, the preparation process parameters are exactly the same except for the carbonization temperature in step S2.

[0088] Step S2: Inert atmosphere carbonization

[0089] The dried bagasse was placed in an inert atmosphere furnace and heated to 500°C at a heating rate of 5°C / min. After holding at this temperature for 2 hours, it was naturally cooled to obtain bagasse-based carbon fiber.

[0090] Comparative Example 3

[0091] This comparative example aims to examine the effect of carbonization temperature on the properties of the composite material. Compared with Example 1, the preparation process parameters are exactly the same except for the carbonization temperature in step S2.

[0092] Step S2: Inert atmosphere carbonization

[0093] The dried bagasse was placed in a nitrogen atmosphere furnace and heated to 900°C at a heating rate of 5°C / min. After holding at this temperature for 2 hours, it was naturally cooled to obtain bagasse-based carbon fiber.

[0094] Comparative Example 4

[0095] This comparative example aims to examine the effect of surface modification on the properties of composite materials. Compared with Example 1, the preparation process parameters are exactly the same except that the surface modification in step S3 is not performed.

[0096] Comparative Example 5

[0097] This comparative example aims to examine the effect of insulating fillers on the properties of composite materials, and no insulating fillers are added. Compared with Example 1, the preparation process parameters are exactly the same except for the different component ratios of the composite materials.

[0098] By weight, the composite material comprises the following components: 30 parts bagasse-based carbon fiber, 54.3 parts epoxy resin, 11.66 parts curing agent, 0.54 parts curing accelerator, 2.9 parts flame retardant, and 0.7 parts anti-aging additive.

[0099] Comparative Example 6

[0100] This comparative example aims to illustrate the effect of surface insulating coating on the properties of composite materials; no insulating coating is applied. Compared to Example 1, the preparation process parameters are exactly the same except for the absence of step S7, the surface insulating coating treatment.

[0101] Comparative Example 7

[0102] This comparative example aims to examine the influence of carbon fiber raw materials on the properties of composite materials. The carbon fiber raw material used in this comparative example is PAN carbon fiber.

[0103] By weight, the composite material comprises the following components: 30 parts PAN carbon fiber, 44.3 parts epoxy resin, 11.76 parts curing agent, 0.44 parts curing accelerator, 10 parts inorganic insulating filler, 2.9 parts flame retardant, and 0.7 parts anti-aging additive.

[0104] The epoxy resin is bisphenol A epoxy resin with an epoxy value of 0.48–0.54; the curing agent is methyltetrahydrophthalic anhydride; the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol; the inorganic insulating filler is a mixture of silica and alumina in a 1:1 mass ratio; the flame retardant is a mixture of aluminum hydroxide and phenylphosphoric acid in a 2:1 mass ratio; and the anti-aging additive is a mixture of antioxidant 1010 and ultraviolet absorber 328 in a 1:1 mass ratio.

[0105] The preparation steps of this composite material are as follows:

[0106] Step S1: Surface Modification

[0107] PAN carbon fibers were placed in an aqueous solution of ethanol containing 1% (w / w) aminopropyltriethoxysilane coupling agent for surface modification to improve their surface activity and interfacial bonding performance with the epoxy resin matrix. The volume ratio of ethanol to deionized water in the aqueous solution was 90:10, and the pH of the solution was 4.

[0108] Step S2: Resin system preparation

[0109] Weigh out epoxy resin, curing agent, inorganic insulating filler, flame retardant and anti-aging additive in proportion, mix and stir evenly, degas under vacuum, and prepare composite resin system.

[0110] Step S3: Compression molding

[0111] PAN-based carbon fiber and the resin system obtained in step S2 are mixed in proportion and placed in a mold for compression molding to prepare a crossbeam blank. The compression molding temperature is 120℃, the molding pressure is 6 MPa, and the holding time is 30 min.

[0112] Step S4: Staged curing

[0113] The molded crossbeam blank was subjected to a staged curing process: pre-curing at 80℃ for 1 hour, then main curing at 120℃ for 2 hours, and finally post-curing at 150℃ for 2 hours to obtain a stable and dense composite material structure.

[0114] Step S5: Surface Insulation Coating Treatment

[0115] The cured crossarm is machined to meet assembly requirements, and a silicone rubber insulating coating with a thickness of 1.0 mm is applied to its surface via dip coating. The machining process includes cutting, drilling, milling, and surface polishing. Specifically, a saw blade is first used to cut the crossarm to a fixed length to achieve the designed dimensions; then, the end face is milled to ensure flatness; next, mounting holes are drilled at predetermined locations; finally, the machined surface is polished to remove burrs.

[0116] Comparative Example 8

[0117] This comparative example aims to examine the effect of staged curing on the properties of the composite material. Compared with Example 1, the preparation process parameters are exactly the same except for the curing stage in step S6.

[0118] Step S6: Curing Stage

[0119] The molded crossbeam blank is subjected to a single heat curing treatment at a curing temperature of 120 ℃ for 2 hours.

[0120] The carbonization temperature and fiber mass fraction of Examples 1-4 are shown in Table 1.

[0121] Table 1 Carbonization temperature and fiber mass fraction in Examples 1-4

[0122]

[0123] The composite insulating crossarms prepared in Examples 1-4 and Comparative Examples 1-8 were tested for flexural strength, volume resistivity and water absorption.

[0124] The flexural strength was tested according to GB / T 9341-2008 standard, using a three-point bending test with an electronic universal testing machine; the volume resistivity was tested according to GB / T 31838.2-2019 standard, using a high-resistivity meter, under room temperature and 50% relative humidity conditions; the water absorption rate was tested according to GB / T 1034-2008 standard, by immersing the samples in room temperature water for 24 hours and then measuring the change in mass. The test data for flexural strength, volume resistivity, and water absorption rate of Examples 1-4 and Comparative Examples 1-8 are shown in Table 2. Figure 2 This is a comparison diagram of the bending strength of the composite insulating crossarms prepared in Examples 1-4 and Comparative Examples 1-8; Figure 3 The diagram shows a comparison of the volume resistivity of the composite insulating crossarms prepared in Examples 1-4 and Comparative Examples 1-8. Figure 4 The graph shows a comparison of the water absorption rates of the composite insulating crossarms prepared in Examples 1-4 and Comparative Examples 1-8.

[0125] Table 2. Test data of flexural strength, volume resistivity, and water absorption of Examples 1-4 and Comparative Examples 1-8.

[0126]

[0127] from Figure 2 , Figure 3 , Figure 4 It can be clearly seen that the composite material insulating crossarms prepared in Examples 1-4 of this invention have significantly better overall performance in terms of mechanical properties, electrical insulation properties and water absorption rate than those in Comparative Examples 1-8.

[0128] As shown in Table 2, in terms of mechanical properties, the composite insulating crossarms of Examples 1-4 all exhibit flexural strengths above 205 MPa, demonstrating excellent mechanical properties and meeting the design requirements of power systems for the load-bearing capacity of insulating crossarms. However, Comparative Example 1, due to the lack of bagasse carbonization treatment, has a flexural strength of only 120 MPa, indicating poor interfacial bonding between the fiber and resin, leading to a decrease in the material's flexural performance. In Comparative Example 4, the bagasse-based carbon fiber, without surface modification, has a flexural strength of only 170 MPa, indicating poor interfacial bonding between the reinforcing phase and the resin matrix, resulting in a significant reduction in flexural strength and making it difficult to meet engineering application requirements. Comparative Example 2 showed that the bagasse carbonized at 500℃, while Comparative Example 3 showed that the bagasse carbonized at 900℃. The flexural strength was within the range of 150-155 MPa, and the overall mechanical properties were significantly reduced. This indicates that carbonization temperature has a significant impact on flexural strength. If the carbonization temperature is too low, the bagasse will not be fully carbonized, leading to a decrease in flexural strength; if the carbonization temperature is too high, excessive carbonization may form microscopic defects such as cracks, which will also reduce flexural strength. Furthermore, Comparative Example 7 used PAN-based carbon fiber as a reinforcing material, achieving a flexural strength of 210 MPa, which is relatively high, but its volume resistivity was only 1.2 × 10⁻⁶. 12 The low Ω·m electrical insulation performance indicates that the bagasse-based carbon fiber composite insulation crossarm, after carbonization and surface modification, exhibits excellent overall performance. Comparative Example 8, prepared using a single-stage curing process, showed a flexural strength of 200 MPa, which is lower than that of Examples 1-4. This suggests that a staged curing process is beneficial for improving the internal structural density of the material, thereby enhancing the flexural strength of the composite.

[0129] Regarding electrical insulation performance, the volume resistivity of the composite material insulating crossarms in Examples 1-4 of this invention is 1.1 × 10⁻⁶. 12 -1.5×10 12 Within the Ω·m range, it exhibits good and stable insulation properties. This is because the bagasse-based carbon fibers, after carbonization and surface modification, can form a stable interfacial structure with the epoxy resin matrix. Furthermore, the introduction of inorganic insulating fillers further improves the electrical insulation performance of the composite material. In contrast, Comparative Example 1, without bagasse carbonization treatment, has a volume resistivity of only 3.0 × 10⁻⁶. 10 The volume resistivity of Ω·m indicates that uncarbonized bagasse fibers are difficult to form a stable insulating structure; Comparative Example 5, without the addition of inorganic insulating fillers, has a volume resistivity of only 5.0 × 10⁻⁶. 11 Ω·m; Comparative Example 6, without a surface insulating coating, has a volume resistivity of 6.0 × 10⁻⁶. 11 The insulation stability decreased to Ω·m.

[0130] Regarding water absorption performance, the water absorption rate of the composite insulating crossarms in Examples 1-4 of this invention ranges from 0.32% to 0.42%, exhibiting a low overall water absorption rate. This indicates that the internal structure of the composite material is relatively dense, and the interface between the fiber and the resin matrix is ​​well-bonded, which is beneficial for improving the long-term stability of the material in humid environments. In contrast, Comparative Example 1, which did not undergo bagasse carbonization treatment, achieved a water absorption rate of 1.25%, indicating a relatively high rate. This suggests that the fiber structure of the uncarbonized bagasse is less stable, and water absorption channels easily form within the material. Comparative Example 5, without the addition of inorganic insulating fillers, had a water absorption rate of 0.60%. Comparative Example 6, without a surface insulating coating, had a water absorption rate of 0.55%. This indicates that the materials have lower density or poor interfacial bonding, making them prone to water absorption, which can affect their long-term weather resistance and insulation stability.

[0131] In summary, the bagasse-based carbon fiber of this invention uses bagasse, a byproduct of the sugar industry, as raw material. Bagasse resources are abundant and inexpensive, giving it significant advantages in terms of economy and sustainability as a fiber-reinforced composite material. This invention utilizes carbonization of bagasse combined with interface modification technology to ensure uniform distribution of reinforcing fibers within the resin matrix, forming a stable interface structure. Furthermore, a well-designed epoxy resin system, the introduction of inorganic insulating fillers, and a staged curing process further optimize the fiber-resin interface and interlayer structure, improving the overall electrical insulation of the composite material and reducing water absorption. This results in a composite insulating crossarm that possesses excellent mechanical properties, superior electrical insulation, and good environmental adaptability, meeting the application requirements of power transmission line insulating crossarms under complex environmental conditions such as high load, high humidity, salt spray, and corrosion.

[0132] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should be covered by the patent of the present invention.

Claims

1. A bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms, characterized in that, By weight, it includes the following components: 25-35 parts bagasse-based carbon fiber, 38-50 parts epoxy resin, 10-13 parts curing agent, 0.2-0.5 parts curing accelerator, 10-15 parts inorganic insulating filler, 2-4 parts flame retardant, and 0.5-0.8 parts anti-aging additive.

2. The bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in claim 1, characterized in that, The inorganic insulating filler is one or both of silicon dioxide and aluminum oxide.

3. The bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in claim 1, characterized in that, The flame retardant is a mixture of aluminum hydroxide and an organophosphorus flame retardant in a mass ratio of 2:

1.

4. The bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in claim 1, characterized in that, The anti-aging additive is a mixture of hindered phenolic antioxidants and ultraviolet light absorbers in a mass ratio of 1:

1.

5. A method for preparing a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in any one of claims 1-4, characterized in that, The preparation steps include the following: Step S1: Bagasse drying pretreatment After selecting bagasse and screening and washing, it is dried at 100-110 ℃ for 10-14 h to remove free moisture. Step S2: Inert atmosphere carbonization The dried bagasse is placed in an inert atmosphere furnace and heated to 600-800℃ at a heating rate of 3-5℃ / min. After holding at this temperature for 1-2 hours, it is naturally cooled to obtain bagasse-based carbon fiber. Step S3: Surface Modification The bagasse-based carbon fiber obtained in step S2 is placed in a silane coupling agent solution for surface modification treatment to obtain surface-modified bagasse-based carbon fiber. Step S4: Resin system preparation Weigh out epoxy resin, curing agent, curing accelerator, inorganic insulating filler, flame retardant and anti-aging additive in proportion, mix and stir evenly, and degas under vacuum to obtain a resin system mixture. Step S5: Compression molding After mixing the surface-modified bagasse-based carbon fiber with the resin system mixture of step S4 in a certain proportion, the mixture is placed in a mold and molded to prepare the crossbeam blank. Step S6: Staged curing The molded crossbeam blank is subjected to a staged curing process; Step S7: Surface Insulating Coating Treatment The cured crossarm is machined to meet assembly requirements, and an insulating coating is applied to its surface by spraying or dipping.

6. The method for preparing a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in claim 5, characterized in that, In step S2, the inert atmosphere of the inert atmosphere furnace is nitrogen or argon.

7. The method for preparing a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in claim 5, characterized in that, In step S3, the silane coupling agent solution is an aqueous solution of aminopropylsilane coupling agent in ethanol with a mass fraction of 1-3%, wherein the volume ratio of ethanol to deionized water is 90:10-95:5, and the pH of the solution is 4-5.

8. The method for preparing a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in claim 5, characterized in that, In step S5, the molding temperature is 110-130℃, the molding pressure is 5-8MPa, and the holding time is 30-40min.

9. The method for preparing a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in claim 5, characterized in that, In step S6, the staged curing process includes a pre-curing stage, a main curing stage, and a post-curing stage. The temperature of the pre-curing stage is 70-90℃, and the holding time is 0.5-1.5h. The curing temperature of the main curing stage is 110-130℃, and the holding time is 1-3h. The curing temperature of the post-curing stage is 140-160℃, and the holding time is 1-3h.

10. The method for preparing a bagasse-based carbon fiber and epoxy resin composite material for composite insulating crossarms as described in claim 5, characterized in that, In step S7, the insulating coating is silicone rubber or a highly insulating epoxy material, and the coating thickness is 0.5-1.0 mm.

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