A method for growing nano-zinc oxide on the surface of glass fiber, glass fiber with nano-zinc oxide grown on the surface and fiber reinforced composite

Abstract

This invention discloses a method for growing nano-zinc oxide on the surface of glass fibers, glass fibers with nano-zinc oxide grown on their surface, and fiber-reinforced composite materials. The method includes: pretreating the glass fibers; preparing an alcoholic solution containing a zinc compound and an alkaline substance as a seed solution; contacting the pretreated glass fibers with the seed solution and drying them to attach zinc oxide nuclei to the surface of the glass fibers; preparing an aqueous solution containing a zinc salt and an organic amine as a precursor solution; placing the nucleated glass fibers and the precursor solution in a sealed reaction vessel for a hydrothermal reaction to grow nano-zinc oxide on the surface of the glass fibers; separating and drying the reaction after completion to obtain glass fibers with nano-zinc oxide grown on their surface. This invention also provides glass fibers prepared by this method and fiber-reinforced composite materials containing these glass fibers.

Description

Technical Field

[0001] This invention relates to the field of glass fiber surface modification technology, specifically to a method for growing nano-zinc oxide on the surface of glass fibers, as well as glass fibers with nano-zinc oxide grown on their surface prepared by the method and fiber-reinforced composite materials containing the glass fibers. Background Technology

[0002] Glass fiber is widely used as a reinforcing material in fiber-reinforced composites due to its high strength and corrosion resistance. Nano-zinc oxide, as a functional nanomaterial, possesses unique physicochemical properties, and its introduction into composite material systems holds promise for endowing materials with new functions and improving their performance.

[0003] In fiber-reinforced composites, the interfacial properties between glass fibers and the resin matrix are a key factor determining the overall mechanical properties of the composite. Untreated glass fiber surfaces are typically smooth, non-polar, and chemically inert, making it difficult for effective mechanical interlocking and chemical bonding to form between the glass fibers and the resin matrix. This results in weak interfacial bond strength, thus limiting further improvements in the overall mechanical properties of the composite.

[0004] Therefore, how to effectively improve the surface properties of glass fiber and enhance its interfacial bonding with the resin matrix is ​​a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for uniformly and firmly growing nano-zinc oxide on the surface of glass fiber, so as to overcome the defects of poor interfacial bonding performance between the smooth surface of glass fiber and resin matrix caused by chemical inertness, thereby improving the overall mechanical properties of fiber reinforced composite materials.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for growing nano-zinc oxide on the surface of glass fiber, comprising the following steps: S1: Pretreatment of glass fiber; S2: Prepare a seed solution, wherein the seed solution is an alcoholic solution containing a zinc compound and an alkaline substance; S3: The glass fiber pretreated in step S1 is brought into contact with the seed solution and dried to allow zinc oxide crystal nuclei to adhere to the surface of the glass fiber. S4: Prepare a precursor solution, wherein the precursor solution is an aqueous solution containing a zinc salt and an organic amine; S5: The glass fiber treated in step S3 and the precursor solution are placed in a sealed reaction vessel and subjected to a hydrothermal reaction to grow nano zinc oxide on the surface of the glass fiber. After the reaction is completed, the glass fiber is separated and dried to obtain glass fiber with nano zinc oxide grown on its surface.

[0007] Further, the pretreatment in step S1 includes washing the glass fiber with deionized water and then drying it. As one embodiment, the drying temperature in step S1 is between 60°C and 120°C.

[0008] Further, in step S2, the zinc-containing compound is zinc acetate or its hydrate, and the alkaline substance is sodium hydroxide or potassium hydroxide. In one embodiment, the alcohol solution is an ethanol solution. Further, in the seed solution, the molar ratio of the zinc-containing compound to the alkaline substance is 1:(2.5 to 3.5), and the concentration of the zinc-containing compound is 8 mmol / L to 12 mmol / L. Further, step S2 also includes stirring the alcohol solution at a temperature of 50°C to 70°C for 1 hour to 3 hours. As one embodiment, the stirring speed is 150 rpm to 450 rpm.

[0009] Further, in step S3, the contact method is immersion, and the immersion time is 1 to 15 minutes. Further, in step S3, the drying temperature is 80°C to 100°C, and the drying time is 20 to 40 minutes.

[0010] Further, in step S4, the zinc salt is zinc acetate or its hydrate, and the organic amine is hexamethylenetetramine. Further, in the precursor solution, the concentration of the zinc salt is 8 mmol / L to 12 mmol / L, and the concentration of the organic amine is 8 mmol / L to 12 mmol / L.

[0011] Further, in step S5, the hydrothermal reaction temperature is 60°C to 100°C, and the reaction time is 4 hours to 10 hours. Further, in step S5, the mass-to-volume ratio of the glass fiber to the precursor solution is 1 g:(80 to 250) mL. Further, in step S5, the filling degree of the sealed reaction vessel is 50% to 85% of the total volume.

[0012] The present invention also provides a glass fiber with nano-zinc oxide grown on its surface, prepared by the method described in any of the preceding claims. Further, the nano-zinc oxide has a nano-columnar structure. Further, the nano-zinc oxide is uniformly distributed on the surface of the glass fiber.

[0013] The present invention also provides a fiber-reinforced composite material comprising glass fibers with nano-zinc oxide grown on their surface as described in any of the above claims as a reinforcing material.

[0014] Compared with the closest prior art, the present invention has the following beneficial effects: This invention first uses a seed solution to attach zinc oxide nuclei to the surface of pretreated glass fibers, and then uses a hydrothermal reaction to allow nano-zinc oxide to grow directionally from these nuclei. The zinc-containing compounds in the seed solution react with alkaline substances in an alcohol solution to generate zinc oxide nuclei. After drying, these nuclei firmly adhere to the glass fiber surface, providing uniform nucleation sites for subsequent hydrothermal growth. Under hydrothermal conditions, the zinc salt and organic amines in the precursor solution slowly release zinc ions and hydroxide ions, promoting the epitaxial growth of zinc oxide crystals along the nuclei to form a uniformly distributed nanostructure. This process transforms the originally smooth, inert glass fiber surface into a nano-zinc oxide coating with a specific morphology (such as nanopillars), significantly increasing the fiber's specific surface area and surface roughness. Simultaneously, the polarity of the nano-zinc oxide surface also enhances the fiber's surface energy. When this modified glass fiber is used as a reinforcing material in composite materials, the increased roughness creates a stronger mechanical interlocking effect with the resin matrix, while the improved surface energy promotes wettability and chemical bonding between the fiber and the resin. This directly and effectively solves the defect of weak interfacial bonding between glass fiber and resin matrix, ultimately resulting in a significant enhancement of the overall mechanical properties of the composite material. By controlling parameters such as seed solution concentration, hydrothermal reaction temperature, and time, the morphology, size, and distribution uniformity of nano-zinc oxide can be regulated, further optimizing the interfacial modification effect. Attached Figure Description

[0015] Figure 1 This is a scanning electron microscope image of the original glass fiber after cleaning and drying. Figure 2 This is a scanning electron microscope image of ZnO nanopillars on the glass fiber surface in Example 1; Figure 3 This is a scanning electron microscope image of ZnO nanopillars on the glass fiber surface in Example 2; Figure 4 This is a process diagram of fiber microstructure testing before and after modification in this invention; Figure 5 This is a comparison chart of the interfacial strength test results of microfibers before and after modification in this invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0017] Glass fiber reinforced composites are widely used in aerospace, automotive, and construction industries. The inventors of this application discovered that the smooth and chemically inert surface of glass fibers in existing technologies results in weak interfacial bonding with the resin matrix, limiting further improvements in the composite material's performance. The method provided in this application, through a step-by-step controlled process, first generates and attaches uniform zinc oxide crystal nuclei in situ on the glass fiber surface as "seeds." Then, under hydrothermal conditions, the zinc oxide crystals are guided to grow epitaxially from these seed sites, thereby constructing a uniformly distributed nano-zinc oxide structure on the glass fiber surface. The nanostructure formed by this method not only significantly increases the fiber surface roughness, enhancing the mechanical interlocking with the resin, but also, the polar groups on the surface of the nano-zinc oxide increase the fiber's surface energy, promoting chemical bonding with the resin. This synergistic enhancement of interfacial properties from both physical and chemical perspectives ultimately improves the overall mechanical strength of the composite material.

[0018] Embodiments of the present invention provide a method for growing nano-zinc oxide on the surface of glass fiber. The method includes the following steps: Step S1: Pre-treat the glass fiber.

[0019] In this step, the purpose of pretreatment is to remove any impurities, oil, or slurry that may be present on the glass fiber surface, providing a clean surface to facilitate subsequent crystal nuclei adhesion. Specifically, pretreatment includes washing the glass fiber with deionized water and then drying it. The drying process removes moisture from the surface and internal pores of the glass fiber, preventing moisture from interfering with the concentration of the subsequent seed solution and the adhesion process. The drying temperature can be controlled between 60°C and 120°C. Within this temperature range, moisture can be effectively removed while avoiding excessively high temperatures that could alter the surface properties of the glass fiber. Preferably, the drying temperature can be 80°C or 100°C, and the drying time is typically 1 to 2 hours.

[0020] Step S2: Prepare seed solution.

[0021] The seed solution is an alcoholic solution containing a zinc-containing compound and an alkaline substance. In this embodiment, the zinc-containing compound can be zinc acetate or its hydrate, the alkaline substance can be sodium hydroxide or potassium hydroxide, and the alcoholic solution can be an ethanol solution. By dissolving the zinc-containing compound and the alkaline substance in ethanol, they react in the alcoholic medium to generate tiny zinc oxide nuclei or precursors, which are the starting point for subsequent hydrothermal growth. In the seed solution, the concentration of the zinc-containing compound is 8 mmol / L to 12 mmol / L, and the molar ratio of the zinc-containing compound to the alkaline substance is 1:(2.5 to 3.5). For example, when the zinc-containing compound is zinc acetate dihydrate, its molar concentration can be set to 10 mmol / L, and the molar ratio with sodium hydroxide can be set to 1:3. This concentration and ratio range helps to generate an appropriate amount of zinc oxide nuclei with suitable particle size, ensuring uniform subsequent growth. If the proportion of the alkaline substance is too low, insufficient nuclei will be generated; if the proportion is too high, it may lead to nuclei agglomeration or the formation of other basic zinc salts.

[0022] To further promote the reaction and ensure uniform mixing of the solution, step S2 also includes stirring the prepared alcohol solution at a temperature of 50°C to 70°C for 1 to 3 hours. The stirring speed can be controlled between 150 rpm and 450 rpm. For example, stirring at 60°C and 300 rpm for 2 hours can ensure that the reaction proceeds fully, resulting in a stable seed solution that provides uniform adhesion points for the glass fibers.

[0023] Step S3: The glass fiber pretreated in step S1 is brought into contact with the seed solution and dried to allow zinc oxide crystal nuclei to adhere to the surface of the glass fiber.

[0024] In this step, immersion is the preferred contact method. Clean, dry glass fibers are immersed in the seed solution for 1 to 15 minutes. Within this time range, the crystal nuclei in the seed solution can be fully adsorbed onto the glass fiber surface. Too short a time may result in insufficient adsorption; too long a time may lead to multilayer adsorption, affecting the uniformity of subsequent growth. After immersion, the glass fibers with attached crystal nuclei need to be dried. The drying temperature is controlled between 80°C and 100°C, and the drying time is 20 to 40 minutes. For example, drying at 90°C for 30 minutes. This drying process promotes solvent evaporation and transforms the zinc oxide precursor adsorbed on the fiber surface into stable zinc oxide crystal nuclei, firmly fixing them to the fiber surface and providing stable and uniformly distributed growth sites for the next hydrothermal growth step.

[0025] Step S4: Prepare the precursor solution.

[0026] The precursor solution is an aqueous solution containing a zinc salt and an organic amine. In this embodiment, the zinc salt can be zinc acetate or its hydrate, and the organic amine can be hexamethylenetetramine. The concentration of the zinc salt in the precursor solution is 8 mmol / L to 12 mmol / L, and the concentration of the organic amine is also 8 mmol / L to 12 mmol / L. For example, both concentrations can be set to 10 mmol / L. Hexamethylenetetramine slowly hydrolyzes under hydrothermal conditions to generate ammonia and formaldehyde. Ammonia reacts with water to produce hydroxide ions, which combine with the zinc ions released from the zinc salt, providing reactants for the continuous and slow growth of zinc oxide crystals. This slow release mechanism facilitates the directional and orderly epitaxial growth of zinc oxide along the crystal nuclei formed in step S3, thereby forming a well-defined nanostructure.

[0027] Step S5: The glass fiber treated in step S3 and the precursor solution are placed in a sealed reaction vessel and subjected to a hydrothermal reaction to allow nano-zinc oxide to grow on the surface of the glass fiber. After the reaction is completed, the glass fiber is separated and dried to obtain glass fiber with nano-zinc oxide growing on its surface.

[0028] Hydrothermal reaction is a crucial step in the formation of nano-zinc oxide structures. In this step, the hydrothermal reaction temperature is controlled between 60°C and 100°C, and the reaction time is between 4 and 10 hours. For example, the reaction temperature can be 90°C, and the reaction time can be 6 hours. This temperature and time range ensures that the zinc oxide crystals have sufficient driving force and time to grow, while avoiding overgrowth, shedding, or morphological deterioration due to excessively high temperature or time. The mass-to-volume ratio of glass fiber to precursor solution is controlled between 1 g:(80 to 250) mL, which ensures that each fiber is fully in contact with the growth solution and receives sufficient reactant supply. In addition, the filling degree of the sealed reaction vessel is controlled between 50% and 85% of the total volume. Appropriate filling degree allows for the establishment of suitable pressure inside the hydrothermal reactor, which is conducive to promoting the reaction and influencing the crystallinity and morphology of the final product. After the reaction is complete, the glass fiber is removed from the solution and washed several times with deionized water to remove residual reactants and byproducts. Finally, it is dried at 60°C to 80°C to obtain glass fiber with nano zinc oxide grown on its surface.

[0029] The glass fibers with nano-zinc oxide grown on their surface, prepared by the above method, have a uniformly distributed nano-columnar structure of zinc oxide on their surface. This uniformly distributed nano-columnar structure significantly increases the specific surface area and surface roughness of the fibers.

[0030] This application also provides a glass fiber with nano-zinc oxide grown on its surface, which is prepared by the method described in any of the above embodiments. Due to the aforementioned seed-layer guided hydrothermal growth process, the nano-zinc oxide on the surface of the prepared glass fiber not only has a nano-columnar structure but also achieves a uniform distribution on the fiber surface. This structural feature is the material basis for its ability to effectively improve the interfacial properties of composite materials.

[0031] This application also provides a fiber-reinforced composite material comprising glass fibers with nano-zinc oxide grown on their surface as reinforcement. When the glass fibers modified by this method are used as reinforcement and combined with a resin matrix (such as epoxy resin, unsaturated polyester, etc.), the uniformly distributed nano-zinc oxide pillars on the fiber surface can embed themselves into the resin like "anchors," forming a strong mechanical interlock. Simultaneously, the polarity of the nano-zinc oxide surface increases the surface energy of the fiber, improves the wettability of the resin to the fiber, and may also lead to certain chemical interactions with it. The synergistic effect of physical interlocking and chemical bonding significantly enhances the interfacial bond strength between the fiber and the resin, thereby effectively transferring the load from the resin matrix to the high-strength glass fibers, ultimately resulting in a significant improvement in the overall mechanical properties of the composite material, such as tensile strength and flexural strength.

[0032] To more intuitively demonstrate the effects of the technical solution of this application, the following description is provided through specific embodiments and comparative examples.

[0033] Example 1 1. Pretreatment: Take glass fiber cloth, ultrasonically clean it with deionized water for 15 minutes, and then dry it in an 80℃ oven for 2 hours.

[0034] 2. Preparation of seed solution: Dissolve 2.195 g of zinc acetate dihydrate (Zn(CH3COO)2·2H2O) and 1.2 g of sodium hydroxide (NaOH) separately in anhydrous ethanol, and bring the volume to 1 L to obtain a seed solution with a zinc compound concentration of 10 mmol / L and a molar ratio of 1:3. Place the solution in a 65°C water bath and magnetically stir at 300 rpm for 2 hours.

[0035] 3. Attaching crystal nuclei: Immerse the pretreated glass fiber cloth in the seed solution for 10 minutes, then remove it and dry it at 90℃ for 30 minutes.

[0036] 4. Preparation of precursor solutions: Dissolve 2.195 g of zinc acetate dihydrate and 1.4 g of hexamethylenetetramine (HMTA) in deionized water and bring the volume to 1 L to obtain precursor solutions with a concentration of 10 mmol / L.

[0037] 5. Hydrothermal Reaction: 1 g of glass fiber cloth with attached crystal nuclei was placed together with 100 mL of precursor solution into a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE) (approximately 85% filling). The reactor was sealed and placed in an oven at 90 °C for 6 hours. After the reaction, the mixture was allowed to cool naturally. The glass fiber cloth was then removed, rinsed repeatedly with deionized water, and finally dried at 70 °C to obtain glass fibers with nano-zinc oxide grown on their surface.

[0038] Example 2 The difference from Example 1 is that the hydrothermal reaction temperature in step 5 is 70°C and the reaction time is 8 hours. The other steps and parameters are the same as in Example 1.

[0039] Example 3 The difference from Example 1 is that in step 2, the concentration of the zinc compound in the seed solution is 8 mmol / L, and the NaOH concentration is adjusted accordingly to maintain a molar ratio of 1:3. Other steps and parameters are the same as in Example 1.

[0040] Comparative Example 1 Steps 2 and 3 (i.e., without preparing and attaching the seed layer) are skipped, and the pretreated glass fiber cloth is directly subjected to the hydrothermal reaction in step 5. Other parameters are the same as in Example 1.

[0041] Comparative Example 2 The hydrothermal reaction in step 5 was skipped; only step 3 (i.e., only the seed layer) was performed. Other parameters were the same as in Example 1.

[0042] Performance testing: The glass fibers obtained in Examples 1-3 and Comparative Examples 1-2 were used as reinforcing materials and epoxy resin were prepared into composite laminates by hand lay-up process. The tensile strength and flexural strength were tested, and the results are as follows: Figure 5 As shown in Table 1.

[0043] Table 1. Properties of glass fiber reinforced composite materials prepared in different embodiments and comparative examples.

[0044] The data above show that the glass fibers with nano-zinc oxide grown on their surface, prepared using the method of this application (Examples 1-3), exhibit significantly higher tensile and flexural strengths than the comparative examples and untreated fibers. Example 1, in particular, achieved the best performance under optimized parameters. Comparative Example 1, lacking a uniform seed layer, resulted in uneven distribution and easy agglomeration of zinc oxide produced by hydrothermal growth, limiting its interface improvement effect. Comparative Example 2, with only a seed layer and no subsequent growth, formed a less significant surface structure, contributing little to performance improvement. This confirms the necessity and synergistic advantages of the two-step process of attaching uniform crystal nuclei with a seed solution followed by controlled epitaxial growth via hydrothermal reaction for constructing effective interface reinforcement structures on glass fiber surfaces. This method achieves significant strengthening of the glass fiber-resin interface by constructing a uniform nano-columnar structure.

Claims

1. A method for growing nano-zinc oxide on the surface of glass fiber, characterized in that, Includes the following steps: S1: Pretreatment of glass fiber; S2: Prepare a seed solution, wherein the seed solution is an alcoholic solution containing a zinc compound and an alkaline substance; S3: The glass fiber pretreated in step S1 is brought into contact with the seed solution and dried to allow zinc oxide crystal nuclei to adhere to the surface of the glass fiber. S4: Prepare a precursor solution, wherein the precursor solution is an aqueous solution containing a zinc salt and an organic amine; S5: The glass fiber treated in step S3 and the precursor solution are placed in a sealed reaction vessel and subjected to a hydrothermal reaction to grow nano zinc oxide on the surface of the glass fiber. After the reaction is completed, the glass fiber is separated and dried to obtain glass fiber with nano zinc oxide grown on its surface.

2. The method for growing nano-zinc oxide on the surface of glass fiber according to claim 1, characterized in that, The pretreatment in step S1 includes: washing the glass fiber with deionized water and then drying it; the drying temperature in step S1 is 60°C to 120°C.

3. The method for growing nano-zinc oxide on the surface of glass fiber according to claim 1 or 2, characterized in that, In step S2, the zinc-containing compound is zinc acetate or its hydrate, and the alkaline substance is sodium hydroxide or potassium hydroxide. The alcohol solution is an ethanol solution; In the seed solution, the molar ratio of the zinc-containing compound to the alkaline substance is 1:(2.5 to 3.5), and the concentration of the zinc-containing compound is 8 mmol / L to 12 mmol / L; Step S2 further includes stirring the alcohol solution at a temperature of 50°C to 70°C for 1 hour to 3 hours; The stirring speed is from 150 rpm to 450 rpm.

4. The method for growing nano-zinc oxide on the surface of glass fiber according to claim 1, characterized in that, In step S3, the contact method is immersion, the immersion time is 1 to 15 minutes, the drying temperature in step S3 is 80°C to 100°C, and the drying time is 20 to 40 minutes.

5. The method for growing nano-zinc oxide on the surface of glass fiber according to claim 1, characterized in that, In step S4, the zinc salt is zinc acetate or its hydrate, the organic amine is hexamethylenetetramine, the concentration of the zinc salt is 8 mmol / L to 12 mmol / L, and the concentration of the organic amine is 8 mmol / L to 12 mmol / L.

6. The method for growing nano-zinc oxide on the surface of glass fiber according to claim 1, characterized in that, In step S5, the temperature of the hydrothermal reaction is 60°C to 100°C, and the reaction time is 4 hours to 10 hours.

7. The method for growing nano-zinc oxide on the surface of glass fiber according to claim 1, characterized in that, In step S5, the mass-to-volume ratio of the glass fiber to the precursor solution is 1 g: (80 to 250) mL.

8. The method for growing nano-zinc oxide on the surface of glass fiber according to claim 6, characterized in that, In step S5, the filling degree inside the sealed reaction vessel is 50% to 85% of the total volume.

9. A glass fiber with nano-zinc oxide grown on its surface, characterized in that, The nano zinc oxide is prepared by the method according to any one of claims 1 to 8, wherein the nano zinc oxide has a nano-columnar structure and is uniformly distributed on the surface of the glass fiber.

10. A fiber-reinforced composite material, characterized in that, The glass fiber with nano-zinc oxide grown on its surface, as described in claim 9, is used as a reinforcing material.

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