Silk protein peptide modified alumina filler, epoxy resin composite material and preparation method thereof

Abstract

This invention discloses a silk fibroin peptide-modified alumina filler, an epoxy resin composite material, and their preparation method. The preparation method of the epoxy resin composite material includes the following steps: S1: Preparation of silk fibroin peptide-modified alumina filler: Silk fibroin peptides are dispersed in water, and alumina filler is added to allow the silk fibroin peptides to be adsorbed onto the surface of the alumina filler; then, after solid-liquid separation and drying, silk fibroin peptide-modified alumina filler is obtained; S2: Preparation of epoxy resin composite material: The silk fibroin peptide-modified alumina filler is mixed evenly with epoxy resin and a curing agent, and then cured to obtain an epoxy resin composite material based on silk fibroin peptide-modified alumina. The epoxy resin composite material obtained utilizes biodegradable silk fibroin peptides to modify the surface of the alumina filler, constructing a three-dimensional thermally conductive network with low interfacial thermal resistance, thereby achieving synergistic optimization of the thermal conductivity and degradability of the epoxy composite material.

Description

Technical Field

[0001] This invention belongs to the field of electrical insulation materials and green power equipment technology, specifically relating to a silk protein peptide modified alumina filler, an epoxy resin composite material, and their preparation methods. Background Technology

[0002] Epoxy resins are widely used in the manufacture of power equipment such as basin insulators, dry-type transformers, and high-voltage instrument transformers due to their excellent dielectric strength, strong mechanical properties, and good processing characteristics. In recent years, highly degradable epoxy resins designed based on breakable dynamic bonds or bio-based monomers have shown good environmental absorption potential and are considered candidate materials for future sustainable power equipment. However, with the trend of power equipment moving towards higher voltage levels and more complex operating environments, heat dissipation has become one of the key factors restricting the improvement of power equipment performance. Epoxy resins have extremely low intrinsic thermal conductivity (approximately 0.15-0.25 W / (m·K)), making it difficult to dissipate the Joule heat generated during equipment operation in a timely manner, which can easily lead to localized overheating and accelerated insulation aging.

[0003] To improve the thermal conductivity of epoxy resins, introducing highly thermally conductive inorganic fillers into the resin matrix is ​​one of the most common and efficient modification strategies. Among these, alumina (Al2O3) has become an ideal filler for thermal conductivity modification of epoxy resins due to its high thermal conductivity, excellent electrical insulation properties, wide availability, and controllable cost. However, as inorganic particles, alumina exhibits significant interfacial incompatibility with organic epoxy resin matrices. While traditional silane coupling agents can improve dispersion and enhance interfacial bonding, they are not biodegradable and hinder the depolymerization of the resin backbone, compromising the overall biodegradability of the material. Therefore, a novel modification strategy that combines interfacial strengthening capabilities with environmentally friendly properties is urgently needed. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing an epoxy resin composite material based on silk fibroin peptide-modified alumina. The epoxy resin composite material obtained by this method utilizes biodegradable silk fibroin peptides to modify the surface of the alumina filler, constructing a three-dimensional thermally conductive network with low interfacial thermal resistance, thereby achieving synergistic optimization of the thermal conductivity and degradability of the epoxy composite material.

[0005] To achieve the above technical objectives, the technical solution adopted by this invention is as follows: The preparation method of the epoxy resin composite material based on silk fibroin peptide-modified alumina includes the following steps: S1: Preparation of silk protein peptide modified alumina filler: Silk protein peptides are dispersed in water, and alumina filler is added to allow the silk protein peptides to be adsorbed onto the surface of the alumina filler; then, through solid-liquid separation and drying, silk protein peptide modified alumina filler is obtained. S2: Preparation of epoxy resin composite material: The silk protein peptide modified alumina filler is mixed evenly with epoxy resin and curing agent, and then cured to obtain epoxy resin composite material based on silk protein peptide modified alumina.

[0006] This invention first prepares alumina filler modified with silk fibroin peptides (SFP). The surface of the alumina inorganic filler is modified using biodegradable silk fibroin peptides (SFP), and then mixed with epoxy resin and a curing agent to prepare an epoxy resin composite material. This achieves synergistic optimization of the thermal conductivity and biodegradability of the epoxy composite material. The small molecular structure (500-5000 Da) of SFP can form an ultrathin, uniform bio-interface layer on the Al2O3 filler surface, effectively reducing interfacial thermal resistance through hydrogen bonding, promoting uniform dispersion of the filler, and guiding its construction of a continuous thermally conductive network. As a green interfacial modifier for the inorganic filler, biodegradable SFP enables the construction of the thermally conductive network and improves the thermal conductivity of the epoxy composite material. Thus, without sacrificing the biodegradability of the highly degradable epoxy resin, the thermal management capability of the epoxy composite material is significantly improved, providing technical support for the future application of highly degradable insulating materials in the high-voltage electrical engineering field.

[0007] Furthermore, the alumina is α-Al₂O₃.

[0008] Furthermore, in step S2, a latent curing accelerator is added; the epoxy resin is a bio-based epoxy monomer containing cleavable ester bonds.

[0009] Furthermore, the latent curing accelerator is a complex of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and phenol in a 1:1 molar ratio (PH-TBD).

[0010] Further, in step S2, the method for uniform mixing is to stir at 65~85 ℃ while simultaneously vacuuming for 35~45 min, then add PH-TBD and continue vacuuming and stirring for 10~15 min; the curing adopts a segmented curing regime of 80 ℃ / 4~5 h + 140 ℃ / 12~14 h.

[0011] The present invention also provides an epoxy resin composite material based on alumina modified with silk protein peptides, which uses biodegradable silk protein peptides to modify the surface of alumina filler to construct a three-dimensional thermally conductive network with low interfacial thermal resistance, thereby achieving synergistic optimization of the thermal conductivity and degradability of the epoxy composite material.

[0012] To achieve this technical objective, the technical solution adopted by the present invention is as follows: the epoxy resin composite material comprises: an epoxy resin matrix and silk protein peptide-modified alumina filler dispersed in the epoxy resin matrix; the silk protein peptide-modified alumina filler comprises alumina particles and silk protein peptides adsorbed on the surface of the alumina particles.

[0013] The present invention also provides a silk protein peptide-modified alumina filler. The epoxy resin composite material prepared by the present invention uses biodegradable silk protein peptides to modify the surface of the alumina filler, thereby constructing a three-dimensional thermally conductive network with low interfacial thermal resistance, and achieving synergistic optimization of the thermal conductivity and degradability of the epoxy composite material.

[0014] To achieve this technical objective, the technical solution adopted by the present invention is as follows: the silk protein peptide modified alumina filler includes: alumina particles, and silk protein peptides adsorbed on the surface of the alumina particles.

[0015] Furthermore, the mass ratio of the silk protein peptide to the alumina is 1:20 to 1:60.

[0016] The present invention also provides a method for preparing alumina filler modified with silk protein peptides. The epoxy resin composite material prepared by the method utilizes biodegradable silk protein peptides to modify the surface of the alumina filler, thereby constructing a three-dimensional thermally conductive network with low interfacial thermal resistance and achieving synergistic optimization of the thermal conductivity and degradability of the epoxy composite material.

[0017] To achieve this technical objective, the technical solution adopted by this invention is: a method for preparing the silk fibroin peptide-modified alumina filler, comprising the following steps: S1.1: Add silk protein peptides to water to prepare an aqueous solution of silk protein peptides; S1.2: Alumina particles are added to the aqueous solution of silk protein peptides to carry out a modification reaction, so that the silk protein peptides are adsorbed on the surface of alumina particles. S1.3: Centrifuge the mixture obtained in step S1.2 to collect the solid product; wash and dry the solid product to obtain silk protein peptide modified alumina filler.

[0018] Further, in step S1.2, the modification reaction is achieved by heating and stirring, and intermittent ultrasonic treatment during the reaction process; the heating and stirring temperature is 60~80 ℃, the rotation speed is 250~350 rpm, and the time is 2~3 h; the specific method of the intermittent ultrasonic treatment is to use an ultrasonic power of 175~250 W, each treatment is 3~8 min, the interval is 8~15 min, and a total of 2~5 treatments are performed.

[0019] The intermittent ultrasonic treatment can break up alumina agglomerates by utilizing the ultrasonic cavitation effect and promote the uniform adsorption of silk protein peptides on the surface of alumina particles. It can also avoid the denaturation of silk protein peptides, cavitation shielding and excessive particle damage caused by continuous ultrasonication, thus balancing modification efficiency and process stability.

[0020] Further, in step S1.3, the centrifugation speed is 7500~8500 rpm and the time is 8~15 min; the specific method of washing and drying is to wash the solid product with deionized water 2~5 times and vacuum dry it at 60~80 ℃ for 10~15 h.

[0021] The present invention has the following advantages over the prior art: 1. Biodegradable silk protein peptides are used as green interface modifiers to replace traditional non-degradable silane coupling agents, taking into account both environmental protection and interface function.

[0022] 2. In a highly degradable epoxy resin matrix, the filler is guided to form a continuous, highly insulating three-dimensional thermally conductive network, thereby achieving synergistic optimization of thermal conductivity and biodegradability. Attached Figure Description

[0023] The following detailed description, in conjunction with the accompanying drawings and embodiments of the present invention, is as follows: Figure 1 This is a schematic diagram of the silk protein peptide-modified alumina of the present invention; Figure 2 These are thermal imaging images of five epoxy resin composite material samples of the present invention as they were cooled from 100 °C. Figure 3 These are images of the degradation solutions of four epoxy resin composite material samples (excluding AS-0 sample) of the present invention after degradation at 160 °C for 0, 1, 2, and 4 h, respectively. Figure 4 This is a comparative graph showing the thermal conductivity, degradation rate, and impact strength of five epoxy resin composite material samples from this invention. Detailed Implementation

[0024] To enhance understanding of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. These embodiments are only used to explain the invention and do not limit the scope of protection of the invention.

[0025] This embodiment provides a method for preparing an epoxy resin composite material based on silk fibroin peptide-modified alumina, comprising the following steps: S1: Preparation of silk protein peptide modified alumina filler: Silk protein peptides are dispersed in water, and alumina filler is added to allow the silk protein peptides to be adsorbed onto the surface of the alumina filler; then, through solid-liquid separation and drying, silk protein peptide modified alumina filler is obtained. S2: Preparation of epoxy resin composite material: The silk protein peptide modified alumina filler is mixed evenly with epoxy resin and curing agent, and then cured to obtain epoxy resin composite material based on silk protein peptide modified alumina.

[0026] Preferably, the alumina is α-Al2O3.

[0027] Preferably, the mass ratio of silk protein peptide to alumina in the silk protein peptide modified alumina filler of the present invention is 1:20 to 1:60. The mass ratio of epoxy resin to silk protein peptide modified alumina filler in the epoxy resin composite material is 1:1.5 to 1:2.

[0028] To test the thermal conductivity and biodegradability of the epoxy resin composite material based on silk fibroin peptide-modified alumina of the present invention, five samples were prepared according to different modified Al2O3 fillers in this embodiment, named AF-0, AS-0, AF-1, AF-2, and AF-3, respectively. The raw materials for preparing the modified Al2O3 filler include Al2O3 (α-Al2O3) particles, silk fibroin peptides, silane coupling agent (KH-560), and water. The proportions of each raw material are shown in Table 1 below.

[0029] Table 1. Raw material ratios required for the preparation of modified Al2O3 fillers

[0030] The information on the raw materials silane coupling agent (KH-560), silk protein peptides and Al2O3 (α-Al2O3) particles in Table 1 above is shown in Table 2 below.

[0031] Table 2. Information on raw materials required for the preparation of modified Al2O3 fillers.

[0032] The detailed characteristics and pretreatment methods of each raw material are as follows: Silane coupling agent (KH-560): Produced by Aladdin Reagent (Shanghai) Co., Ltd., with the chemical formula C9H. 20 O5Si, purity ≥97%; it is a colorless and transparent liquid, easily soluble in organic solvents, and easily hydrolyzed in water; the epoxy groups in its molecular structure can react with epoxy resin, and the methoxysilane end can bond with the hydroxyl groups on the surface of inorganic fillers, thereby improving the interfacial compatibility between fillers and resins; it should be sealed and stored in a cool and dry place before use, and moisture should be prevented during handling.

[0033] Silk protein peptides: Produced by Xi'an Nans Biotechnology Co., Ltd., these are natural silk protein peptide powders with a molecular weight range of 1000–5000 Da. Their main components are short-chain polypeptides composed of amino acids such as glycine, alanine, and serine. They are prepared using an alkaline hydrolysis method, contain no solvent residue, and exhibit good water solubility and biocompatibility. Before use, store in a desiccator at room temperature to avoid moisture absorption and clumping. Weighing must be performed in a dry environment to prevent degradation.

[0034] Al2O3 (α-Al2O3) particles: provided by Hefei Kejing Materials Technology Co., Ltd., with a particle size of 5–10 μm, purity ≥99.5%, and specific surface area of ​​approximately 10–15 m². 2 / g; The surface of the particles is rich in hydroxyl groups (–OH), which is conducive to hydrogen bonding with the amino (–NH2) and carboxyl (–COOH) groups in silk protein peptides; Before use, the Al2O3 particles are placed in a vacuum drying oven and baked at 120 °C for 2 h to remove the surface adsorbed moisture and organic impurities. After cooling to room temperature, they are sealed and stored for later use.

[0035] In step S1, in order to obtain Al2O3 filler with surface-modified silk protein peptides, the silk protein peptides are first dispersed in water, preferably deionized water, and Al2O3 filler is added. The silk protein peptides are fully adsorbed onto the surface of the filler by stirring and ultrasonic assistance. Then, after solid-liquid separation and low-temperature drying, Al2O3 filler with surface-modified silk protein peptides is obtained.

[0036] Meanwhile, according to the silk fibroin peptide incorporation quality from low to high, AF-0, AF-1, AF-2 and AF-3 sample fillers were prepared respectively for subsequent preparation of epoxy resin composite materials.

[0037] Specifically, the steps for preparing silk fibroin peptide-modified alumina filler (taking AF-2 sample filler as an example) include: S1.1: Preparation of silk protein peptide solution: Accurately weigh 2.0 g of silk protein peptide and 98.0 g of deionized water according to the mass ratio of Al2O3 particles: silk protein peptide: deionized water = 60:2:98; add the silk protein peptide to the deionized water, stir and ultrasonically disperse at 30~50 ℃ (preferably 40 ℃) for 20~30 min (preferably 30 min) to prepare a uniform and transparent 2wt% silk protein peptide aqueous solution.

[0038] S1.2: Modification reaction: Weigh 60 g of Al2O3 particles that have been pretreated by drying at 120 ℃ for 2 h, and add them to the prepared silk protein peptide aqueous solution. React under mechanical stirring conditions of 60~80 ℃ (preferably 60 ℃) and 250~350 rpm (preferably 300 rpm) for 2~3 h (preferably 2 h). During the reaction, intermittent ultrasonic treatment is performed with an ultrasonic power of 175~250 W (preferably 200 W). Each treatment lasts for 3~8 min (preferably 5 min), with an interval of 8~15 min (preferably 10 min). The treatment is repeated 2~5 times (preferably 3 times) to promote the uniform adsorption of silk protein peptides on the surface of Al2O3 filler.

[0039] S1.3: Post-processing: After the reaction, the mixture is centrifuged at 7500-8500 rpm (preferably 8000 rpm) for 8-15 min (preferably 10 min), and the solid product is collected. The obtained solid is washed with deionized water 2-5 times (preferably 3 times) to remove physically adsorbed silk protein peptides. Finally, the washed packing is placed in a vacuum drying oven and dried at 60-80 ℃ (preferably 80 ℃) for 10-15 h (preferably 12 h) to obtain silk protein peptide-modified Al2O3 packing, labeled as AF-2 sample packing. A schematic diagram of silk protein peptide-modified alumina is shown below. Figure 1 As shown.

[0040] In addition, the specific preparation steps for the AS-0 sample packing are as follows: Weigh 1 g of KH-560 and 99 g of deionized water according to the formula, mix them, and stir magnetically for 10-30 minutes (preferably 25 minutes) to ensure complete hydrolysis. Then slowly add 60 g of Al2O3 particles and continue stirring until a uniform slurry is formed. Transfer the slurry to a reaction vessel and heat it at 60-90 ℃ (preferably 80 ℃) under reflux for 1-3 hours (preferably 2 hours). After the reaction is completed, filter the mixture and wash the filter cake 2-3 times with anhydrous ethanol or deionized water. Place the washed filter cake in a forced-air drying oven at 80-100 ℃ (preferably 100 ℃) and dry it to constant weight. Finally, grind the cake and pass it through a 200-mesh sieve to obtain the AS-0 sample packing.

[0041] In step S2, Al2O3 filler modified with silk fibroin peptide (SFP) is mixed with highly degradable epoxy resin and curing agent. The highly degradable epoxy resin uses a bio-based epoxy monomer containing cleavable ester bonds, and a latent curing accelerator system is a complex of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and phenol in a 1:1 molar ratio. After the mixture is heated, stirred and dispersed evenly, it is degassed under vacuum, poured into a mold, and cured by stepwise heating to obtain a degradable epoxy resin composite material based on silk fibroin peptide modified alumina (Al2O3@SFP / epoxy composite material).

[0042] Preferably, the epoxy resin is bisphenol A diglycidyl ether epoxy resin (E51); the curing agent is methyltetrahydrophthalic anhydride (Me-THPA).

[0043] The raw material information for step S2 is shown in Table 3 below.

[0044] Table 3. Raw material information for the preparation of epoxy composite materials

[0045] The preparation and pretreatment of raw materials for epoxy composite materials include: 1. Place each filler in a vacuum drying oven and preheat it at 80 ℃ for later use.

[0046] 2. Clean the mold with anhydrous ethanol, then apply the release agent evenly and preheat it at the same temperature for 12 hours.

[0047] 3. Raw materials shall be weighed according to the ratio of E51:Me-THPA:Al2O3@SFP:PH-TBD=100:84.66:180:5.

[0048] Specifically, the steps for preparing epoxy resin composite materials include: S2.1: Weigh the raw materials according to the formula (E51: 50 g, Me-THPA: 42.33 g, Al2O3@SFP: 90 g, PH-TBD: 2.5 g; except for the accelerator PH-TBD) into the reactor, place it on the heating jacket, stir at 65~85 ℃ (preferably 80 ℃) and simultaneously vacuum for 35~45 min (preferably 40 min); then add PH-TBD, and continue vacuum stirring for 10~15 min (preferably 10 min).

[0049] S2.2: Slowly pour the degassed and uniformly mixed reactants into a preheated mold, and then transfer the mold to a vacuum drying oven; set a segmented curing regime of 80 ℃ / 4~5 h (preferably 4 h) + 140 ℃ / 12~14 h (preferably 12 h), to ensure the initial gel crosslinking of the epoxy system in the low-temperature pre-curing stage, and to drive the epoxy-anhydride system to complete deep crosslinking in the high-temperature curing stage, thus constructing a complete dynamic ester exchange network; after curing, place the sample in an oven to cool down slowly and demold the sample to obtain Al2O3@SFP / epoxy composite material (AF-0~AF-3 samples).

[0050] In addition, the preparation method of Al2O3@KH560 / epoxy composite material (AS-0 sample) is the same as that of Al2O3@SFP / epoxy composite material; the raw materials are weighed according to E51:Me-THPA:Al2O3@KH560:PH-TBD=100:84.66:180:5, and the specific weighing amounts are E51: 50 g, Me-THPA: 42.33 g, Al2O3@KH560: 90 g, and PH-TBD: 2.5 g.

[0051] In this embodiment, the method for testing the thermal conductivity of the prepared epoxy composite material is as follows: To measure the effect of the filler / matrix interface on the thermal conductivity of epoxy resin composites, thermal images of five epoxy resin composites were taken using a handheld thermal imager (model: HIKMICRO, manufacturer: Hangzhou Weiying Software Co., Ltd.), such as... Figure 2 As shown; during the test, the sample was heated to 100 ℃, and the temperature change process from 100 ℃ to natural cooling was filmed, with a measurement time of 240 s. From Figure 2 As can be seen, when the silk protein peptide addition is 2% (the content of silk protein peptide in the aqueous solution), i.e., the AF-2 sample, its maximum temperature is always lower than that of the other four groups of epoxy resin composite materials due to its higher interfacial bonding strength.

[0052] The thermal conductivity of composite materials was tested using the transient hot-wire method. A TC3000E thermal conductivity meter was used to measure the thermal conductivity of the prepared samples at room temperature. An internal fine metal wire was used as the heat source, and a constant heat flux was applied at the start of the test to induce a transient temperature rise in the sample. The temperature rise curve was obtained in real time by monitoring the change in the resistance of the hot wire, and the result was calculated using the ideal model formula of the hot-wire method. Analysis is performed; in the formula, λ is the temperature rise of the hot wire at time t (the change relative to the initial temperature), in K (or °C); q is the heating power per unit length of the hot wire (constant line heat source power), in W / m; λ is the thermal conductivity of the material being tested (a physical quantity to be determined), in W / (m·K); a is the thermal diffusivity of the material being tested, in m² / s; t is the heating / testing time, in s; r0 is the radius of the hot wire (metal wire), in m; C is an instrument constant related to the geometry and material properties of the hot wire; combined with the sample size and test conditions, the thermal conductivity of the material is directly calculated and output using the instrument's built-in algorithm.

[0053] According to international standard ISO 22007-2:2015, the thermal conductivity of epoxy resin composite materials was tested using a TC3000E thermal conductivity tester (transient hot wire method). The sample was a disc-shaped specimen with a diameter of 40 mm and a thickness of 5 mm. Measurements were taken at room temperature for 5 seconds, and the final output included the thermal conductivity and accuracy evaluation results. The thermal conductivity results of the five epoxy resin composite material samples in this embodiment are as follows: Figure 4 As shown in the image.

[0054] The method for testing the biodegradability of the prepared epoxy composite material in this embodiment is as follows: The degradability was assessed by placing the sample in an ethylene glycol solution containing 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), reacting at 160 °C for 4 hours, cooling, washing, drying, and recording the mass loss rate to evaluate the degradability of the material under catalytic alcoholysis conditions.

[0055] Specifically, 10-11 mL of ethylene glycol and 1.1 g of catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were added to the reaction vessel and mixed thoroughly. Each sample, after curing and weighing (W1=1 g), was completely immersed in the above solution and heated to 160 °C for 4 hours. The degradation solutions of the four groups of epoxy resin composite samples (excluding AS-0 samples) after degradation at 160 °C for 0, 1, 2, and 4 hours are shown below. Figure 3As shown, with prolonged degradation time, the solution color of the four groups of epoxy resin composite samples gradually deepened from nearly colorless to yellowish-brown, with the color depth AF-3>AF-2>AF-1>AF-0. This is because the catalytic effect of silk fibroin peptide-modified alumina accelerated the degradation process, making the sample with more silk fibroin peptides darker in color. After the reaction, the system was allowed to cool naturally to room temperature. The samples were then removed and thoroughly washed with a suitable solvent (such as water or ethanol) to remove residual solution from the surface, and then dried. The dried samples were weighed again (W2, AF-0, AS-0, AF-1~AF-3 were 0.62 g, 0.69 g, 0.6 g, 0.55 g, and 0.38 g, respectively). Based on the mass change before and after the reaction, the mass loss rate (%), i.e., the degradation rate, was calculated using the formula (W1-W2) / W1. The results are shown in the figure. Figure 4 As shown, this is used to evaluate the biodegradability of epoxy resin composites.

[0056] The method for testing the mechanical properties of the prepared epoxy composite material in this embodiment is as follows: According to the testing specifications for the impact strength of epoxy resin in GB / T2571-1995, impact strength tests were conducted on standard impact samples of epoxy resin. The impact testing instrument used was the ZLCED-5.5 composite impact tester from Jinan Zhongluchang Testing Machine Manufacturing Co., Ltd., and the test sample was a standard bending test specimen. The instrument displayed the final experimental result value; no further calculations were required. The results are as follows: Figure 4 As shown.

[0057] The above-mentioned surface modification of alumina (Al2O3) with silk fibroin peptides (SFP) was used to prepare Al2O3@SFP / epoxy composites (AF-0~AF-3) with different silk fibroin peptide contents. Simultaneously, Al2O3@KH560 / epoxy composite (AS-0) was also prepared. The effects of silk fibroin peptide addition on the thermal conductivity, mechanical properties, and biodegradability of the composites were systematically studied. The results are as follows: Figure 4 As shown.

[0058] Figure 4 The results showed that the introduction of silk fibroin peptides significantly regulated thermal conductivity and biodegradability. The thermal conductivity initially increased and then decreased with increasing silk fibroin peptide content, with AF-2 (2% silk fibroin peptides) reaching a maximum of 0.5 W / m·K, significantly higher than other samples. AF-0 had the lowest thermal conductivity, possibly due to interfacial defects caused by unmodified materials. The thermal conductivity of AS-0, AF-1, and AF-3 were 0.46, 0.47, and 0.48 W / m·K, respectively, which were relatively close. The impact strength also showed a trend of first increasing and then decreasing, with AF-2 being the highest, 15.8% higher than AF-0 (12.24 kJ / m²). This indicates that an appropriate amount of silk protein peptides forms a uniform thin layer on the Al2O3 surface, improving interfacial bonding, reducing interfacial thermal resistance, and enhancing toughness. However, excessive silk protein peptides (3%, AF-3) may lead to thickening or agglomeration of the coating layer, which in turn hinders heat conduction and causes stress concentration, resulting in a decrease in performance. The thermal conductivity of AF-3 decreased to 0.48, and the impact strength decreased to 12.49. In terms of biodegradability, the degradation rate of epoxy composites increases with the increase of silk protein peptide content. AF-3 has the highest degradation rate at 62%, followed by AF-2 at 45%, and then AF-1, AF-0, and AS-0.

[0059] In summary, the optimal ratio for adding silk fibroin peptides (the content of silk fibroin peptides in the aqueous solution) is between 2% and 2.5%, achieving a synergistic improvement in thermal conductivity and mechanical properties while maintaining good degradation performance. This invention provides experimental evidence for the biochemical modification of Al2O3-based fillers and their application in biodegradable composite materials.

[0060] This invention utilizes biodegradable silk protein peptides to modify the surface of inorganic thermally conductive fillers in alumina, constructing a three-dimensional thermally conductive network with low interfacial thermal resistance. This solves the technical problems of insufficient thermal conductivity of highly degradable epoxy resins used for high-voltage electrical insulation and the degradation of its biodegradability by traditional interfacial modifiers, providing key technical support for the future application of highly degradable insulating materials in the field of high-voltage electrical engineering.

[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an epoxy resin composite material based on silk fibroin peptide-modified alumina, characterized in that, Includes the following steps: S1: Preparation of silk protein peptide modified alumina filler: Silk protein peptides are dispersed in water, and alumina filler is added to allow the silk protein peptides to be adsorbed onto the surface of the alumina filler; then, through solid-liquid separation and drying, silk protein peptide modified alumina filler is obtained. S2: Preparation of epoxy resin composite material: The silk protein peptide modified alumina filler is mixed evenly with epoxy resin and curing agent, and then cured to obtain epoxy resin composite material based on silk protein peptide modified alumina.

2. The method for preparing epoxy resin composite material based on silk fibroin peptide-modified alumina according to claim 1, characterized in that, In step S2, a latent curing accelerator is added; the epoxy resin is a bio-based epoxy monomer containing cleavable ester bonds.

3. The method for preparing epoxy resin composite material based on silk fibroin peptide-modified alumina according to claim 2, characterized in that, The latent curing accelerator is a complex of 1,5,7-triazabicyclo[4.4.0]dec-5-ene and phenol in a molar ratio of 1:

1.

4. The method for preparing the epoxy resin composite material based on silk fibroin peptide-modified alumina according to claim 1, characterized in that, In step S2, the method for uniform mixing is to stir at 65~85 ℃ while simultaneously vacuuming for 35~45 min, then add PH-TBD and continue vacuuming and stirring for 10~15 min; the curing adopts a segmented curing regime of 80 ℃ / 4~5 h + 140 ℃ / 12~14 h.

5. An epoxy resin composite material based on silk fibroin peptide-modified alumina, characterized in that, include: An epoxy resin matrix and silk protein peptide-modified alumina filler dispersed in the epoxy resin matrix; The silk protein peptide-modified alumina filler includes alumina particles and silk protein peptides adsorbed on the surface of the alumina particles.

6. A silk fibroin peptide-modified alumina filler, characterized in that, include: Alumina particles, and silk protein peptides adsorbed on the surface of the alumina particles.

7. The silk fibroin peptide-modified alumina filler according to claim 6, characterized in that, The mass ratio of the silk protein peptide to the alumina is 1:20 to 1:

60.

8. A method for preparing silk fibroin peptide-modified alumina filler, characterized in that, Includes the following steps: S1.1: Add silk protein peptides to water to prepare an aqueous solution of silk protein peptides; S1.2: Alumina particles are added to the aqueous solution of silk protein peptides to carry out a modification reaction, so that the silk protein peptides are adsorbed on the surface of alumina particles. S1.3: Centrifuge the mixture obtained in step S1.2 to collect the solid product; wash and dry the solid product to obtain silk protein peptide modified alumina filler.

9. The method for preparing silk fibroin peptide-modified alumina filler according to claim 8, characterized in that, In step S1.2, the modification reaction is achieved by heating and stirring, and intermittent ultrasonic treatment during the reaction process; the heating and stirring temperature is 60~80 ℃, the rotation speed is 250~350 rpm, and the time is 2~3 h; the specific method of the intermittent ultrasonic treatment is to use an ultrasonic power of 175~250 W, each treatment is 3~8 min, the interval is 8~15 min, and a total of 2~5 treatments are performed.

10. The method for preparing silk fibroin peptide-modified alumina filler according to claim 8, characterized in that, In step S1.3, the centrifugation speed is 7500~8500 rpm and the time is 8~15 min; the specific method of washing and drying is to wash the solid product with deionized water 2~5 times and vacuum dry it at 60~80 ℃ for 10~15 h.

Images