An epoxy resin composite material prepared using wind turbine blades and its preparation method

Abstract

This invention relates to the field of solid waste treatment technology, and discloses an epoxy resin composite material prepared using wind turbine blades and its preparation method. The epoxy resin composite material includes an epoxy resin matrix, filler, diluent, and curing agent. The filler accounts for 10-25% of the weight of the epoxy resin matrix. The filler is modified wind turbine blade powder that has been treated sequentially with an activation liquid and a silane coupling agent. The wind turbine blade powder is obtained by cutting, crushing, and sieving fiber-reinforced epoxy resin-based wind turbine blades. The activation liquid is a mixture of sodium hydroxide and anhydrous ethanol. The silane coupling agent is a reactive silane coupling agent that can chemically react with epoxy groups. This invention improves the interfacial bonding force between the wind turbine blade and the epoxy resin matrix through activation and modification treatment, thereby obtaining a high-performance epoxy resin composite material and realizing the high-value recycling of waste wind turbine blades.

Description

Technical Field

[0001] This invention relates to the field of solid waste treatment technology, specifically to an epoxy resin composite material prepared using wind turbine blades and its preparation method. Background Technology

[0002] Wind turbine blades are mainly made of thermosetting resin and fiber materials. They are one of the core components of wind turbine generators, with a service life of 20-25 years. As time goes by, early wind turbine blades gradually enter their retirement period, and their green recycling and high-value utilization have become urgent needs of the industry. Since thermosetting resin materials cannot be reshaped after curing and the waste is difficult to handle, the current mainstream method for treating wind turbine blades is to crush them into powder and add them as fillers to the resin matrix to prepare resin composite materials. However, due to the poor compatibility and uneven dispersion of wind turbine blade powder (especially the fiber materials) with epoxy resin, the performance of epoxy resin composite materials is directly affected. This results in a significant reduction in the mechanical properties and high-temperature resistance of the composite material compared to the matrix resin, which cannot meet production requirements.

[0003] Existing technology (Preparation and Performance Study of Epoxy Resin Composites Reinforced by Pyrolysis Products of Waste Wind Turbine Blades, Journal of Environmental Engineering, Vol. 18, No. 5, May 2024) uses the products from the pyrolysis of non-metallic powder from waste wind turbine blades as fillers, triethylenetetramine as a curing agent, epoxy resin as a matrix, and ceramic powder and KH-560 coupling agent as additives to prepare composite materials, achieving the recycling and reuse of waste wind turbine blades. However, this method mainly utilizes the fibers after pyrolysis of wind turbine blades, resulting in limited utilization of the blades and low utilization rate. Furthermore, the process of utilizing wind turbine blades after pyrolysis is difficult and consumes a lot of energy. (See also...) Figure 1 and Figure 5 In comparison, it can be seen that the surface of the blade powder fiber becomes smooth after pyrolysis, the organic residue on the fiber surface is destroyed, and the bonding between the blade pyrolysis products and the epoxy resin interface is difficult. This results in poor mechanical properties of epoxy resin composite materials prepared by existing technologies (the tensile strength of P-RWTBs-2%KH-560 / 20%CP / EP composite material prepared after treatment with 2% KH-560 is 55.59MPa and the flexural strength is 86.43MPa), which cannot meet the material requirements for non-load-bearing structures with clear requirements for strength and durability. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method and application for preparing epoxy resin composite materials using wind turbine blades. The aim is to improve the interfacial bonding force between the wind turbine blade powder (especially the fibers therein) and the epoxy resin matrix by activating and modifying the wind turbine blades, thereby obtaining high-performance epoxy resin composite materials and realizing the high-value recycling of waste wind turbine blades.

[0005] To achieve the above objectives, the present invention provides the following technical solutions.

[0006] First, the present invention provides an epoxy resin composite material prepared using wind turbine blades, the epoxy resin composite material comprising an epoxy resin matrix, fillers, diluents and curing agents, wherein the amount of fillers added accounts for 10-25% of the weight of the epoxy resin matrix.

[0007] The filler is modified wind turbine blade powder that has been sequentially treated with an activation liquid and a silane coupling agent. The wind turbine blade powder is obtained by cutting, crushing, and sieving fiber-reinforced epoxy resin-based wind turbine blades. The activation liquid is a mixture of sodium hydroxide and anhydrous ethanol. The silane coupling agent is a reactive silane coupling agent that can chemically react with epoxy groups. The filler provided by this invention is obtained from wind turbine blade powder through activation and modification treatment, without undergoing pyrolysis, high temperature, or resin removal treatment throughout the process.

[0008] The method for preparing the modified wind turbine blade powder includes the following steps: Step 1: The wind turbine blade powder is immersed in the activation solution for activation treatment, and then the activated wind turbine blade powder is obtained through filtration, drying and sieving processes. Step 2: The activated wind turbine blade powder is added to the hydrolysate of the silane coupling agent for modification treatment, and then the modified wind turbine blade powder is obtained through cooling, filtration and drying processes. The hydrolysate of the silane coupling agent is obtained by adding the silane coupling agent to an alcohol-water mixture and reacting for 20-30 minutes. The activation treatment conditions are an activation solution temperature of 60°C and a soaking time of 2-4 hours. The modification treatment conditions are a silane coupling agent hydrolysate temperature of 60-80°C and a reaction time of 2-4 hours.

[0009] Compared to existing pyrolysis techniques for wind turbine blades, this invention directly uses wind turbine blades to prepare epoxy resin composite materials. By utilizing the similarity between the organic matter on the surface of the wind turbine blade fibers and epoxy resin, the interfacial bonding force between the blade and the resin matrix is ​​enhanced, improving material performance and increasing blade utilization while reducing pyrolysis energy consumption.

[0010] This invention selects fiber-reinforced epoxy resin-based wind turbine blade powder, which is activated and modified, and then added as a filler to an epoxy resin matrix to prepare a high-performance composite material. The wind turbine blade fibers play an irreplaceable skeletal reinforcing role in the composite material. However, the wind turbine blade powder (especially the glass fibers) and the epoxy resin matrix only have physical adsorption and mechanical interlocking, resulting in weak interfacial bonding. Activation and modification transform the powder from an "inert filler" into an "active reinforcing phase," a key step in achieving high-performance, high-value-added recycling. This invention uses an activating solution and a silane coupling agent to modify the powder, constructing strong chemical bridges between the powder surface and the epoxy resin matrix. The silanol (-Si-OH) generated after silane hydrolysis condenses with the hydroxyl groups on the powder surface, forming strong Si-O-Si covalent bonds, thus anchoring the coupling agent on the powder surface. Meanwhile, the organic functional groups at the other end of the silane react chemically with the epoxy resin system, improving interfacial properties. Anhydrous ethanol in the activation solution first removes contaminants from the powder surface and slightly swells the fiber surface. Then, sodium hydroxide etches the silica network in the glass fiber, introducing physical defects such as microcracks and depressions on the fiber surface and generating a large number of silanol active groups. These defects enhance the mechanical interlocking between the fiber and epoxy resin through the "locking effect," while the silanol groups can form chemical bonds with the epoxy resin, thus significantly improving the interfacial bonding strength. The activation step of this invention is not a conventional alkaline treatment, but rather employs an ethanol + sodium hydroxide two-component activation system: ethanol swells the surface resin, and NaOH etches the fiber to generate silanol groups; the two work synergistically to produce a dual strengthening effect of mechanical locking and chemical bonding.

[0011] After modification with silane coupling agents, the organic functional groups of reactive silanes anchored on the surface of wind turbine blade powder (such as the amino group of KH550 and the epoxy group of KH560) can directly participate in the curing network of epoxy resin, constructing strong covalent bonds "molecular bridges" between the filler and the matrix. This significantly improves the mechanical strength, modulus, and impact toughness of the composite material, and endows it with excellent water resistance and long-term durability. Meanwhile, the fibers in the powder are bonded to the new epoxy resin matrix through strong chemical bonds, which can efficiently transfer and disperse stress, thereby significantly improving the tensile strength, flexural modulus, impact toughness, and creep resistance of the composite material. This results in a qualitative leap in its mechanical properties, approaching the level of traditional reinforcing materials.

[0012] The epoxy resin composite material prepared using wind turbine blades provided by this invention does not significantly change the mechanical properties and high-temperature resistance of the matrix resin. It can be used as a replacement material for the matrix resin in fields with clear requirements for material strength and durability, such as high-performance prefabricated building components (e.g., artificial stone, repair mortar), transportation components (e.g., automotive interior panels, railway auxiliary products), industrial facilities (e.g., chemical storage tank liners, cable protection troughs), and emerging composite material 3D printing, etc. It effectively solves the problem of high-value recycling of retired wind turbine blades, and also alleviates the production cost pressure caused by the high price of epoxy resin raw materials.

[0013] Furthermore, in the method for modifying wind turbine blade powder with silane coupling agent, the weight ratio of the silane coupling agent to the wind turbine blade powder is (0.05-0.2):1. Excessive silane coupling agent will cause over-coating of the powder, affecting material properties.

[0014] Furthermore, in some embodiments of the present invention, the weight ratio of the epoxy resin matrix, diluent, and curing agent is 1:1:3. There are no particular requirements regarding the types of epoxy resin, diluent, and curing agent. The epoxy resin matrix can be a common bisphenol A type epoxy resin. The diluent's main function is to reduce resin viscosity and decrease air bubbles; a commercially available epoxy resin diluent can be used. An epoxy resin curing agent is selected.

[0015] Furthermore, the fineness of the wind turbine blade powder is 200 mesh. Larger powder sizes result in poorer mechanical properties of the prepared epoxy resin composite material; appropriate powder fineness facilitates the coating of the coupling agent and improves material performance.

[0016] Furthermore, the silane coupling agent is selected from at least one of KH550, KH560, KH561, KH792, and KH540. The amino groups of KH550, KH792, and KH540 can react efficiently with the epoxy groups to open the ring, while the epoxy groups of KH560 and KH561 can participate in the epoxy curing network.

[0017] Secondly, the present invention provides a method for preparing the above-mentioned epoxy resin composite material, which includes the following steps: Step 1: The wind turbine blades are cut, crushed, and then sieved to obtain wind turbine blade powder; Step 2: Prepare an activation solution by mixing sodium hydroxide and anhydrous ethanol. The concentration of sodium hydroxide in the activation solution is 2 mol / L. Soak the wind turbine blade powder in the activation solution at 60°C for 2-4 minutes, then separate and dry to obtain activated wind turbine blade powder. Step 3: Add the silane coupling agent to the alcohol-water mixture and react for 20-30 minutes to obtain a silane coupling agent hydrolysate. Add the activated wind turbine blade powder to the silane coupling agent hydrolysate and stir evenly. React at 60-80℃ for 2-4 hours. After cooling to room temperature, filter the liquid to obtain a filter cake. Dry the filter cake at 80℃ to obtain modified wind turbine blade powder. The alcohol-water mixture consists of water and alcohol compounds in a volume ratio of 1:(8-10). The weight ratio of the silane coupling agent to the activated wind turbine blade powder is (0.05-0.2):1. The amount ratio of the activated wind turbine blade powder to the alcohol-water mixture is 1g:5mL. Step 4: Mix the epoxy resin matrix, modified wind turbine blade powder, diluent and curing agent in a weight ratio of 1:(0.1-0.2):1:3 to obtain a composite material mixture solution; Step 5: Curing the composite material mixture solution to obtain the epoxy resin composite material.

[0018] Furthermore, in some embodiments of the present invention, the curing method in step 5 is a staged temperature rise curing, specifically, curing at 60-90℃ for 1-3 hours first, and then curing at 100-140℃ for 2-4 hours.

[0019] Furthermore, in step 3, the filter cake is dried at 80°C and then passed through a 200-mesh sieve to obtain modified wind turbine blade powder.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes the structural similarity between wind turbine blades and epoxy resin to prepare epoxy resin composites by adding wind turbine blade powder as a filler into an epoxy resin matrix. The wind turbine blades are activated with an activator and modified with a silane coupling agent to improve the interfacial bonding between the wind turbine blade powder (especially the fibers) and the epoxy resin matrix, thereby obtaining high-performance epoxy resin composites. The prepared epoxy resin composites can be widely used as alternatives to epoxy resins in non-load-bearing structural applications where strength and durability are critical, such as high-performance prefabricated building components (e.g., artificial stone, repair mortar), transportation components (e.g., automotive interior panels, railway auxiliary products), industrial facilities (e.g., chemical storage tank linings, cable protection troughs), and emerging composite material 3D printing. This enables the high-value recycling of waste wind turbine blades while alleviating the production cost pressure of epoxy resins, resulting in significant economic benefits. Attached Figure Description

[0021] Figure 1 SEM image of wind turbine blade powder; Figure 2 This is a SEM image of the activated wind turbine blade powder from Example 1; Figure 3 Photographs of the composite material prepared in Example 1; Figure 4 Photographs of the composite material prepared in Comparative Example 1; Figure 5 This is a SEM image of wind turbine blade powder after pyrolysis. Figure 6 This is a test diagram of the contact angle of the wind turbine blade powder in Example 1; Figure 7 This is a contact angle test diagram of the activated wind turbine blade powder in Example 1; Figure 8 This is a contact angle test diagram of the unactivated modified wind turbine blade powder in Example 1; Figure 9 This is a contact angle test diagram of the activated and modified wind turbine blade powder in Example 1; Figure 10 This is a test diagram of the contact angle of wind turbine blade powder after pyrolysis. Figure 3 and Figure 4 In the diagram, the first row contains bending strength test strips, and the second row contains tensile strength test strips. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the materials and equipment used in the following embodiments and comparative examples can be obtained through commercially available channels.

[0023] The wind turbine blade powder used in the following examples and comparative examples was obtained by cutting, crushing, and sieving waste fiber-reinforced epoxy resin-based wind turbine blades. The powder was sieved through a 200-mesh sieve. Its morphology was observed using a scanning electron microscope. Figure 1 As shown. Simultaneously, 10g of wind turbine blade powder was weighed into a crucible and subjected to pyrolysis in a muffle furnace, with a heating rate set at 10℃·min. -1 The temperature was set at 500–750℃ and held constant for 5–8 hours until pyrolysis was complete. The morphology of the pyrolysis products was then observed using a scanning electron microscope. Figure 5 As shown.

[0024] Example 1: Prepare epoxy resin composite materials according to the following steps: S1. Powder Activation: Dissolve sodium hydroxide in water to prepare a concentrated solution, then dilute with anhydrous ethanol to a concentration of 2 mol / L to obtain an activation solution. Immerse the wind turbine blade powder in the activation solution at 60℃ for 2-4 hours, then separate and dry to obtain activated wind turbine blade powder. Observe its morphology using a scanning electron microscope, such as... Figure 2 As shown.

[0025] S2. Preparation of alcohol-water mixture: Mix water and ethanol at a volume ratio of 1:(8-10) to obtain alcohol-water mixture; S3. Add silane coupling agent KH560 to the alcohol-water mixture and stir until homogeneous. React for 20-30 minutes to obtain a silane coupling agent hydrolysate. Then, add the activated wind turbine blade powder to the aforementioned silane coupling agent hydrolysate and stir until homogeneous. React at 60°C for 4 hours. After cooling to room temperature, filter the liquid to obtain a filter cake. Dry the filter cake at 80°C for 5 hours and pass it through a 200-mesh sieve to obtain modified wind turbine blade powder. The weight ratio of silane coupling agent to activated wind turbine blade powder is 0.1:1, and the volume ratio of activated wind turbine blade powder to alcohol-water mixture is 1g:5mL. S4. Epoxy resin matrix, modified wind turbine blade powder, diluent, and curing agent are mixed uniformly at a weight ratio of 1:0.2:1:3 to obtain a composite material mixture solution; wherein, the epoxy resin matrix is ​​bisphenol A type epoxy resin, the diluent is D-921 (chemical name: benzyl glycidyl ether, CAS number: 89616-40-0), and the curing agent is D230 (chemical name: polyetheramine, CAS number: 9046-10-0). S4. The composite material mixture is cured using a staged temperature-increasing curing method to obtain the epoxy resin composite material. Specifically, the composite material mixture is first cured at 80°C for 2 hours, and then cured at 120°C for 2 hours. The resulting epoxy resin composite material is shown below. Figure 3 As shown.

[0026] Figure 1 and Figure 2 The comparison shows that the activation solution damaged the fibers in the wind turbine blade powder, mainly in two ways: First, the fiber surface developed microcracks, etching pits, and peeling marks due to alkaline etching, forming obvious defect structures. Second, the fibers underwent brittle fracture under the combined action of etching and mechanical stirring, with originally long fibers becoming significantly shorter, resulting in a large number of short fiber segments. Furthermore, a small amount of silicate fragments generated by the alkaline etching reaction or incompletely removed residues adhered to the fiber surface. These deposits further demonstrate that the alkaline solution effectively destroyed the original fiber structure, while increasing surface roughness and active sites, which is beneficial for subsequent mechanical and chemical bonding with epoxy resin. Therefore, the activation treatment resulted in obvious defects on the fiber surface, allowing for better epoxy resin penetration and improving the performance of the prepared material.

[0027] The activation treatment (NaOH + anhydrous ethanol) of this invention generates a large number of silanol groups (-Si-OH) on the surface of glass fibers. These are highly polar, high-surface-energy hydrophilic groups that significantly reduce the contact angle between water droplets and solid surfaces. In the modification treatment, the silane coupling agent replaces the hydrophilic silanol groups (-Si-OH) on the fiber surface with hydrophobic organic groups (such as amino, epoxy, or long-chain alkyl groups) through a chemical reaction, significantly reducing the surface free energy of the solid. Simultaneously, the original micro-rough structure further amplifies the hydrophobic effect, making it more difficult for water droplets to spread. Therefore, the contact angle of wind turbine blade powder decreases after activation treatment and increases after modification treatment. Furthermore, using water and a mixture of epoxy resin and curing agent as media, the contact angles of wind turbine blade powder, activated wind turbine blade powder, unactivated but modified wind turbine blade powder, activated and modified wind turbine blade powder, and wind turbine blade powder after pyrolysis (tablet testing) were measured. The results are shown in [reference needed]. Figures 6 to 10 As shown, Figures 6 to 9 This indicates that the wind turbine blade powder successfully achieved the activation and modification objectives through the activation and modification steps of this invention, and the activated and modified wind turbine blade powder exhibited the highest compatibility with the "epoxy resin + curing agent" mixture. Figure 10 This indicates that the bonding force between pyrolysis powder and epoxy resin is poor. The main reason for this is that although the high temperature removes the original epoxy resin residue on the powder surface, exposing the fiber and significantly reducing the water contact angle, it also destroys the silanol active sites and micro-roughness defects introduced by alkali activation, resulting in increased chemical inertness of the fiber surface and decreased physical interlocking ability. Therefore, although the pyrolysis powder has good wettability to water, its interfacial compatibility with the epoxy resin mixture is significantly lower than that of activated powder and activated modified powder, making it difficult to form strong chemical bonds and mechanical interlocking.

[0028] Example 2: Similar to Example 1, except that the wind turbine blade powder was modified directly without the activation step of S1.

[0029] Example 3: Similar to Example 1, except that in step S2 the weight ratio of silane coupling agent to wind turbine blade powder is 0.05:1.

[0030] Example 4: Similar to Example 1, except that in step S2 the weight ratio of silane coupling agent to wind turbine blade powder is 0.2:1.

[0031] Example 5: Similar to Example 1, except that in step S3, the epoxy resin matrix, modified wind turbine blade powder, diluent and curing agent are mixed evenly in a weight ratio of 1:0.1:1:3.

[0032] Example 6: Similar to Example 1, except that in step S2, the wind turbine blade powder is added to the silane coupling agent hydrolysate and reacted at 100°C for 2 hours.

[0033] Example 7: Same as Example 1, except that KH550 was chosen as the silane coupling agent.

[0034] Example 8: Same as Example 1, except that KH561 was selected as the silane coupling agent.

[0035] Example 9: Same as Example 1, except that KH792 was chosen as the silane coupling agent.

[0036] Example 10: Same as Example 1, except that KH540 was chosen as the silane coupling agent.

[0037] The mechanical and heat resistance data of the epoxy resin composite materials prepared in the above examples were tested and compared with the data of the resin matrix (bisphenol A type epoxy resin) used in the examples. The results are shown in Table 1 below.

[0038] The tensile and flexural strengths of the materials were tested using a universal testing machine. For tensile strength testing, a standard dumbbell-shaped specimen with dimensions of 75 mm × 4 mm × 2 mm was used, with a constant force of 10 kN, a tensile speed of 2.0 mm / min, and a gauge length of 25 mm. For flexural strength testing, a standard specimen with dimensions of 80 mm × 15 mm × 4 mm was used, employing a three-point bending test with a constant force of 10 kN, an impact speed of 2 mm / min, and a wheelbase of 32 mm.

[0039] Dynamic thermomechanical analysis (DMA) is used to obtain the onset temperature of the storage modulus of a material, thereby evaluating its heat resistance. The onset temperature of the storage modulus refers to the temperature at which the storage modulus (E') of the material begins to decrease sharply with increasing temperature during DMA testing. It is the critical temperature at which the material begins to lose rigidity, marking the starting point of the material's transition from a rigid (glassy) state to a soft (elastic or viscous flow) state. It is an important indicator for evaluating the material's dimensional stability and load-bearing capacity at high temperatures.

[0040] As can be seen from Table 1 below, the mechanical and heat resistance properties of the composite materials prepared in Examples 1 to 6 are superior to those of the resin matrix (bisphenol A type epoxy resin) used. The addition of wind turbine blade powder improves the performance of the composite materials.

[0041] Comparative Example 1: Prepare epoxy resin composite materials according to the following steps: S1. Dilute silane coupling agent KH560 with ethanol solvent to obtain a silane coupling agent dilution solution with a concentration of 0.5wt%; S2. Add the wind turbine blade powder to the above-mentioned silane coupling agent dilution solution, stir at a speed of 550-650 r / min for 10-30 min, and then cool to 20-30℃; wherein, the weight ratio of silane coupling agent to wind turbine blade powder is 0.1:1. S3. The mixed liquid of S2 is first mixed evenly with the epoxy resin matrix and diluent, and then mixed evenly with the curing agent to obtain a composite material solution; wherein, the epoxy resin matrix, wind turbine blade powder, diluent and curing agent are mixed in a weight ratio of 1:0.2:1:3, the epoxy resin matrix is ​​bisphenol A type epoxy resin, the diluent is D-921, and the curing agent is D230; S4. The above composite material mixture solution is cured by a staged temperature increase curing method, specifically by first curing at 80°C for 2 hours and then curing at 120°C for 2 hours.

[0042] See the cured material. Figure 4 As shown, comparison Figure 3 and Figure 4 It is evident that the specimens of Example 1 and Comparative Example 1 have a significant difference in appearance. The material of Comparative Example 1 is noticeably convex and bent, and the tensile specimen breaks at a narrower point in the middle, making it impossible to test its mechanical properties. In contrast, the specimen of Example 1 is flat and uniform, and has good mechanical properties.

[0043] The reasons for this may be related to whether the silane coupling agent is hydrolyzed and the insufficient modification of the wind turbine blade powder by the silane coupling agent. The silane coupling agent must first be hydrolyzed to generate active silanol (-Si-OH) to undergo an efficient condensation reaction with the hydroxyl groups on the powder surface, thereby forming a strong chemical anchor on the powder surface. If an unhydrolyzed coupling agent is added directly, it is difficult to effectively bond with the powder and is prone to self-polymerization or premature reaction in the resin matrix, leading to interface modification failure. Simultaneously, sufficient powder modification treatment (such as controlling the concentration of the hydrolysate, reaction time, and drying conditions) is crucial. It ensures that the coupling agent forms a uniform, continuous, and dense molecular bridge layer on the fiber and resin powder surfaces, minimizing unmodified areas and interface defects. Only when these two steps work synergistically can the recycled powder be transformed from an inert filler into an active reinforcing phase, achieving strong chemical bonding between the powder and the new matrix, excellent stress transfer, and excellent durability, thus obtaining a high-performance recycled composite material.

[0044] Comparative Example 2: Prepare epoxy resin composite materials according to the following steps: Bisphenol A type epoxy resin matrix, wind turbine blade powder, D-921 diluent and D230 curing agent were mixed evenly in a weight ratio of 1:0.2:1:3 to obtain a composite material solution. The solution was then cured by a staged temperature increase curing method, specifically by first curing at 80℃ for 2 hours and then at 120℃ for 2 hours.

[0045] The mechanical and heat resistance properties of the cured material were tested according to the above testing methods, and the results are shown in Table 1 below.

[0046] As can be seen from Table 1 below, due to the poor dispersibility of unmodified wind turbine blade powder, the mechanical properties and heat resistance of the composite material obtained by directly mixing it with the epoxy resin matrix are significantly reduced compared to the matrix resin.

[0047] Comparative Example 3: Same as Example 1, except that the silane coupling agent selected is A171 (vinylsilane).

[0048] The mechanical and heat resistance properties of the cured material were tested according to the above testing methods, and the results are shown in Table 1 below.

[0049] As can be seen from Table 1 below, since A171 does not contain active organic functional groups that react chemically with the epoxy resin system, it can only provide physical coating for the powder and improve the powder dispersibility, but it cannot establish strong chemical bonds between the powder and the epoxy resin, thus its performance improvement of the composite material is limited.

[0050] Comparative Example 4: Similar to Example 1, except that in step S3, the epoxy resin matrix, modified wind turbine blade powder, diluent and curing agent are mixed evenly in a weight ratio of 1:0.3:1:3.

[0051] The mechanical and heat resistance properties of the cured material were tested according to the above testing methods, and the results are shown in Table 1 below.

[0052] As can be seen from Table 1 below, excessive modified powder affects the mechanical properties and heat resistance of the composite material.

[0053] Table 1. Mechanical and heat resistance data of the composite materials prepared in the examples and comparative examples.

[0054] In summary, it can be seen that by activating and modifying wind turbine blade powder, and by controlling the concentration of coupling agent hydrolysate, the reaction temperature and time between the powder and hydrolysate, the wind turbine blade powder can be fully modified. At the same time, by controlling the amount of modified powder added, high-performance epoxy resin composite materials can be obtained as alternative materials to epoxy resin, alleviating the production cost pressure of epoxy resin and realizing the high-value recycling of waste wind turbine blades.

[0055] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, any improvements and modifications made based on the core ideas of the present invention without departing from the spirit and scope of the present invention should be considered within the scope of protection of the present invention.

Claims

1. An epoxy resin composite material prepared using wind turbine blades, characterized in that: The epoxy resin composite material includes an epoxy resin matrix, fillers, diluents, and curing agents, wherein the fillers account for 10-25% of the weight of the epoxy resin matrix. The filler is modified wind turbine blade powder that has been treated with an activation liquid and a silane coupling agent in sequence. The wind turbine blade powder is obtained by cutting, crushing and sieving fiber-reinforced epoxy resin-based wind turbine blades. The activation liquid is a mixture of sodium hydroxide and anhydrous ethanol. The silane coupling agent is a reactive silane coupling agent that can chemically react with epoxy groups. The method for preparing the modified wind turbine blade powder includes the following steps: Step 1: The wind turbine blade powder is immersed in the activation solution for activation treatment, and then the activated wind turbine blade powder is obtained through filtration, drying and sieving processes. Step 2: The activated wind turbine blade powder is added to the hydrolysate of the silane coupling agent for modification treatment, and then the modified wind turbine blade powder is obtained through cooling, filtration and drying processes. The hydrolysate of the silane coupling agent is obtained by adding the silane coupling agent to an alcohol-water mixture and reacting for 20-30 minutes. The activation treatment conditions are: activation solution temperature 60℃, soaking time 2-4 hours, sodium hydroxide concentration in the activation solution 2 mol / L, and modification treatment conditions are: silane coupling agent hydrolysate temperature 60-80℃, reaction time 2-4 hours.

2. The epoxy resin composite material according to claim 1, characterized in that: In the method for modifying wind turbine blade powder with silane coupling agent, the weight ratio of the silane coupling agent to the wind turbine blade powder is (0.05-0.2):

1.

3. The epoxy resin composite material according to claim 1, characterized in that: The weight ratio of the epoxy resin matrix, diluent, and curing agent is 1:1:

3.

4. The epoxy resin composite material according to claim 1, characterized in that: The fineness of the wind turbine blade powder is 200 mesh.

5. The epoxy resin composite material according to claim 1, characterized in that: The silane coupling agent is selected from at least one of KH550, KH560, KH561, KH792, and KH540.

6. The method for preparing the epoxy resin composite material according to any one of claims 1 to 5, characterized in that: Includes the following steps: Step 1: The wind turbine blades are cut, crushed, and then sieved to obtain wind turbine blade powder; Step 2: Prepare an activation solution by mixing sodium hydroxide and anhydrous ethanol. Soak the wind turbine blade powder in the activation solution at 60°C for 2-4 hours, then separate and dry to obtain activated wind turbine blade powder. Step 3: Add the silane coupling agent to the alcohol-water mixture and react for 20-30 minutes to obtain a silane coupling agent hydrolysate. Add the activated wind turbine blade powder to the silane coupling agent hydrolysate and stir evenly. React at 60-80℃ for 2-4 hours. After cooling to room temperature, filter the liquid to obtain a filter cake. Dry the filter cake at 80℃ to obtain modified wind turbine blade powder. The alcohol-water mixture consists of water and alcohol compounds in a volume ratio of 1:(8-10). The weight ratio of the silane coupling agent to the activated wind turbine blade powder is (0.05-0.2):

1. The amount ratio of the activated wind turbine blade powder to the alcohol-water mixture is 1g:5mL. Step 4: The epoxy resin matrix, modified wind turbine blade powder, diluent and curing agent are mixed evenly at a weight ratio of 1:(0.1-0.2):1:3 to obtain a composite material mixture solution; Step 5: Curing the composite material mixture solution to obtain the epoxy resin composite material.

7. The preparation method according to claim 6, characterized in that: The curing method in step 5 is a staged temperature rise curing, specifically curing at 60-90℃ for 1-3 hours first, and then curing at 100-140℃ for 2-4 hours.

8. The preparation method according to claim 6, characterized in that: In step 3, the filter cake is dried at 80°C and then passed through a 200-mesh sieve to obtain modified wind turbine blade powder.

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