Hydrophobic nanosilica modified basalt fiber and preparation method thereof

Abstract

This invention discloses a hydrophobic nano-silica modified basalt fiber and its preparation method. The method includes using basalt fiber as a matrix, introducing silicon-oxygen bonds through hydrolysis and condensation with a silane coupling agent, and then constructing a "micro-nano dual structure" through chemical bonding and physical adsorption of hydrophobic nano-SiO2. The hydrophobic nano-SiO2 is trimethylchlorosilane-modified gas-phase SiO2. The preparation process includes three steps: fiber pretreatment, silanization treatment, and nano-SiO2 grafting. By optimizing parameters such as ultrasonic power, reaction temperature, and dispersion concentration, the surface roughness of the modified basalt fiber is improved, enhancing the interfacial adhesion between the basalt fiber and the asphalt matrix. The method is simple and controllable, suitable for asphalt pavement engineering, and improves its durability.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, specifically to a hydrophobic nano-silica modified basalt fiber and its preparation method. Background Technology

[0002] Basalt fiber, as a novel inorganic non-metallic material, is often used as a reinforcing phase in asphalt mixtures in road engineering to improve the pavement's resistance to rutting and cracking. However, the inherent defects on the surface of basalt fiber limit its engineering application effectiveness:

[0003] (1) Insufficient interfacial bonding: The fiber surface is smooth and rich in hydroxyl groups (-OH), which are highly hydrophilic and have poor compatibility with the hydrophobic asphalt matrix. The interfacial bonding force is weak, and fiber-asphalt peeling is prone to occur when subjected to load, resulting in a decrease in the mechanical properties of the mixture.

[0004] (2) Poor hydrophobicity and stability: The hydroxyl groups on the surface of unmodified fibers easily adsorb water, which reduces the water stability of the mixture under conditions such as freeze-thaw cycles and rainwater erosion.

[0005] (3) Limitations of existing modification methods: The commonly used single silane coupling agent treatment (such as KH550) can only form a single chemical film on the fiber surface, with limited improvement in surface roughness (Ra value is usually <5 nm), and cannot construct a three-dimensional rough structure. Furthermore, the nanoparticles are prone to agglomeration during modification, resulting in low loading rate (<1%), making it difficult to simultaneously meet the requirements for synergistic improvement of hydrophobicity, roughness and interfacial adhesion.

[0006] In the prior art, the patent with publication number CN120717732A is entitled "A High Asphalt-Stone Ratio Durable Basalt Fiber Asphalt Mixture with Low-Temperature Crack Resistance and Its Preparation Method". Although this patent also optimizes the problem of asphalt cracking and loosening in low-temperature environment through pretreatment, its process is too complicated and the improvement of low-temperature crack resistance is not significant. Summary of the Invention

[0007] Objective of the Invention: This invention proposes a hydrophobic nano-silica modified basalt fiber, which simultaneously improves hydrophobicity and interfacial adhesion by constructing a three-dimensional micro / nano structure. This invention also provides a method for preparing the aforementioned hydrophobic nano-silica modified basalt fiber.

[0008] Technical Solution: This invention proposes a hydrophobic nano-silica modified basalt fiber, comprising using basalt fiber as a matrix, grafting a silane coupling agent and hydrophobic nano-SiO2 onto the surface of the basalt fiber, wherein the silane coupling agent is an amino-containing silane; the hydrophobic SiO2 is trimethylchlorosilane-modified gas-phase SiO2; the silane coupling agent forms Si-O-Si covalent bonds on the surface of the basalt fiber through hydrolysis and condensation, and the grafting is completed after introducing amino active sites; the hydrophobic nano-SiO2 is chemically bonded to the amino group of the silane coupling agent and physically adsorbed and anchored onto the surface of the basalt fiber to complete the grafting, and the surface of the grafted basalt fiber exhibits micro-nano protrusions.

[0009] Preferably, the hydrophobic nano-SiO2 has a particle size of 20-50 nm and a surface hydroxyl content of <2 hydroxyl groups / nm².

[0010] Preferably, the hydrolysis of the silane coupling agent involves dissolving the silane coupling agent in anhydrous ethanol to form a hydrolysis system, wherein the volume ratio of the silane coupling agent to anhydrous ethanol is 1:20, and the pH value of the hydrolysis system is 5.

[0011] Preferably, the hydrophobic nano-SiO2 in the dispersion has a mass ratio of 1.4%-1.8%, and the dispersion also contains 0.5% silane coupling agent with a pH value of 6.

[0012] Preferably, the silane coupling agent is KH550.

[0013] A method for preparing hydrophobic nano-silica modified basalt fibers includes the following steps:

[0014] Pretreatment of basalt fibers;

[0015] The silane coupling agent is dissolved, the pH value is adjusted and ultrasonically dispersed to form a reaction solution. The pretreated basalt fiber is immersed in the reaction solution for water bath reaction. The basalt fiber after the reaction is completed is taken out, cleaned and dried to solidify to obtain silanized basalt fiber.

[0016] Hydrophobic nano-SiO2 was added to a dispersion, ultrasonically dispersed, and the pH value was adjusted to form a suspension. Silanized basalt fibers were added to the suspension for a water bath reaction. The silanized basalt fibers that had completed the reaction were taken out, washed, and dried to obtain modified basalt fibers.

[0017] Preferably, the pretreatment in step one specifically includes placing the basalt fiber in an acetone solution, ultrasonically cleaning it, rinsing it with deionized water until neutral, and then drying it in an oven. The ultrasonic cleaning power is 200-300W, the time is 15-30 minutes, the oven temperature is 80℃, and the drying time is 2 hours.

[0018] Preferably, the basalt fiber, after pretreatment, has a moisture content of ≤0.2%, a diameter of 9-15 μm, a length of 6-12 mm, and a surface hydroxyl exposure rate of ≥90%.

[0019] Preferably, step two specifically includes dissolving the silane coupling agent in anhydrous ethanol at a volume ratio of 1:20, adjusting the pH to 5 with glacial acetic acid, ultrasonically dispersing at 300-400W for 30-45 minutes to form a reaction solution, immersing the pretreated basalt fiber in the reaction solution, and reacting with shaking in a water bath at 65-75℃ for 1-2 hours. After removing the pretreated basalt fiber, rinsing it with ethanol, and then placing it in an oven at 120℃ for 1-2 hours to cure it, the silanized basalt fiber is obtained.

[0020] Preferably, step three specifically includes adding hydrophobic nano-SiO2 to an ethanol solution at a mass ratio of 1.4%-1.8% (ethanol solution concentration is 90%), ultrasonically dispersing at 300-400W for 30-45 minutes, adding 0.5% KH550 to adjust the pH to 6, and then ultrasonically dispersing at 300-400W for 15-30 minutes to form a suspension; immersing silanized basalt fibers in the suspension, stirring and reacting in a water bath at 65-75℃ for 1-2 hours, removing the reacted silanized basalt fibers, rinsing with anhydrous ethanol, and drying in a 120℃ oven for 1-2 hours to obtain modified basalt fibers.

[0021] Beneficial Effects: This invention proposes a method for preparing hydrophobic nano-silica modified basalt fiber. Through the dual action of "chemical grafting with silane coupling agent and physical anchoring with hydrophobic nano-SiO2," a three-dimensional micro / nano rough structure is constructed on the surface of the basalt fiber, improving its hydrophobicity, surface roughness, and interfacial adhesion to matrices such as asphalt. The preparation method of the hydrophobic nano-silica modified basalt fiber is stable, cost-controllable, and highly efficient. The microstructure, interfacial properties, and engineering applicability of the prepared modified basalt fiber are superior to existing modification technologies, meeting the needs of large-scale engineering applications. Attached Figure Description

[0022] Figure 1 This is a SEM image of the modified basalt fibers prepared in Example 1 of the present invention;

[0023] Figure 2 This is a SEM image of the modified basalt fibers prepared in Example 2 of the present invention;

[0024] Figure 3 This is a SEM image of the modified basalt fibers prepared in Example 3 of the present invention;

[0025] Figure 4 This is a SEM image of the modified basalt fibers prepared in Example 4 of the present invention;

[0026] Figure 5 This is a SEM image of the modified basalt fibers prepared in Example 5 of the present invention;

[0027] Figure 6 This is a SEM image of the modified basalt fibers prepared in Example 6 of the present invention;

[0028] Figure 7 This is a SEM image of the basalt fibers prepared in Comparative Example 1 of this invention.

[0029] Figure 8 This is a SEM image of the basalt fibers prepared in Comparative Example 2 of this invention.

[0030] Figure 9 This is a SEM image of the basalt fibers prepared in Comparative Example 3 of this invention.

[0031] Figure 10 The FTIR spectra of the modified basalt fiber prepared in Example 3 of the present invention, the basalt fiber in Comparative Example 1, and the hydrophobic nano-silica are shown. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The present invention proposes a hydrophobic nano-silica modified basalt fiber and its preparation method. The raw materials used include: basalt fiber (Jiangsu Tianlong Basalt Continuous Fiber Co., Ltd.); silane coupling agent: KH550 (analytical grade, containing amino groups), Sinopharm Group; hydrophobic nano-SiO2: trimethylchlorosilane modified gas-phase SiO2, i.e., TMCS modified gas-phase SiO2, with a particle size of 20-50 nm and a surface hydroxyl content of <2 hydroxyl groups / nm², Evonik Industries Group. The Ra value was measured using SEM (Zeiss Sigma 300), the hydrophobicity was measured using a contact angle meter (KRÜSS DSA100), and the interfacial bond strength with asphalt was measured using a pull-out tester.

[0033] A hydrophobic nano-silica modified basalt fiber comprises basalt fiber as a matrix, with a silane coupling agent and hydrophobic nano-SiO2 grafted onto the surface of the basalt fiber. The silane coupling agent is an amino-containing silane; the hydrophobic SiO2 is trimethylchlorosilane-modified gas-phase SiO2. The silane coupling agent forms Si-O-Si covalent bonds on the surface of the basalt fiber through hydrolysis and condensation, introducing amino active sites to complete the grafting. The hydrophobic nano-SiO2 is chemically bonded to the amino groups of the silane coupling agent and physically adsorbed and anchored onto the surface of the basalt fiber, thus completing the grafting. The grafted basalt fiber surface exhibits micro- and nano-protrusions, such as... Figure 1-6 As shown, the micro-nano protrusion is shaped like a cauliflower.

[0034] A hydrophobic nano-silica modified basalt fiber and its preparation method include the following steps:

[0035] Basalt fibers are placed in acetone solution and ultrasonically cleaned at 200-300W for 15-30 minutes, rinsed with deionized water until neutral, and dried in an oven at 80℃ for 2 hours. After pretreatment, the basalt fibers have a moisture content of ≤0.2%, a diameter of 9-15μm, a length of 6-12mm, and a surface hydroxyl exposure rate of ≥90%, ensuring that the hydroxyl groups on the surface of the basalt fibers are fully exposed.

[0036] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The solution was ultrasonically dispersed at 300-400W for 30-45 minutes to form a reaction solution. The pretreated basalt fibers were immersed in the reaction solution and reacted in a water bath at 65-75℃ for 1-2 hours. The reacted basalt fibers were then removed, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 1-2 hours to obtain silanized basalt fibers. KH550 formed Si-O-Si covalent bonds on the surface of the basalt fibers through hydrolysis and condensation, introducing amino active sites.

[0037] Hydrophobic nano-SiO2 was added to an ethanol solution at a mass ratio of 1.4-1.8% (ethanol concentration was 90%), and ultrasonically dispersed at 300-400W for 30-45 min. 0.5% KH550 was added to adjust the pH to 6, and then ultrasonically dispersed at 300-400W for 15-30 min to form a suspension. Silanized basalt fibers were immersed in the suspension and stirred in a water bath at 65-75℃ for 1-2 h. The reacted silanized basalt fibers were then rinsed with anhydrous ethanol and dried in a 120℃ oven for 1-2 h to obtain modified basalt fibers. The hydrophobic nano-SiO2 was anchored to the surface of the basalt fibers through chemical bonding (reaction with the silane coupling agent amino) and physical adsorption (van der Waals forces). After grafting, the surface of the basalt fibers exhibited "cauliflower-like" micro-nano protrusions.

[0038] Example 1

[0039] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 25°C and 200W for 15 minutes, rinsed with deionized water until neutral, and dried in an oven at 80°C for 2 hours.

[0040] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The mixture was ultrasonically dispersed at 300W for 30 minutes to form a reaction solution. The pretreated basalt fiber was immersed in the reaction solution and reacted in a water bath at 65℃ for 1 hour. The basalt fiber after the reaction was completed was taken out, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 1 hour to obtain silanized basalt fiber.

[0041] Hydrophobic nano-SiO2 was added to an ethanol solution at a mass ratio of 1.6% (90% ethanol concentration), and ultrasonically dispersed at 300W for 30 min. 0.5% KH550 was added to adjust the pH to 6, and then ultrasonically dispersed at 300W for 15 min to form a suspension. Silanized basalt fibers were immersed in the suspension and stirred in a 70℃ water bath for 1 h. The reacted silanized basalt fibers were then rinsed with anhydrous ethanol and dried in a 120℃ oven for 1 h to obtain modified basalt fibers.

[0042] SEM images of the prepared modified basalt fibers are shown below. Figure 1 As shown, the performance of modified basalt fiber was tested; the tensile strength of the modified basalt fiber monofilament was 92.4%, the elastic modulus was 95.8 MPa, the surface roughness (Ra value) was 23.5 nm, the contact angle was 93°, and the interfacial bond strength with asphalt was 2.7 MPa.

[0043] Example 2

[0044] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 240W for 25 minutes at 25℃, rinsed with deionized water until neutral, and dried in an oven at 80℃ for 2 hours.

[0045] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The mixture was ultrasonically dispersed at 360W for 40 minutes to form a reaction solution. The pretreated basalt fibers were immersed in the reaction solution and reacted in a water bath at 70℃ for 2 hours. The basalt fibers that had completed the reaction were taken out, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 1.5 hours to obtain silanized basalt fibers.

[0046] Hydrophobic nano-SiO2 was added to an ethanol solution at a mass ratio of 1.6% (90% ethanol concentration), and ultrasonically dispersed at 360W for 40 min. 0.5% KH550 was added to adjust the pH to 6, and then ultrasonically dispersed at 360W for 15 min to form a suspension. Silanized basalt fibers were immersed in the suspension and stirred in a 65℃ water bath for 1.5 h. The reacted silanized basalt fibers were then rinsed with anhydrous ethanol and dried in a 120℃ oven for 1.5 h to obtain modified basalt fibers.

[0047] SEM images of the prepared modified basalt fibers are shown below. Figure 2 As shown, the performance of modified basalt fiber was tested; the tensile strength retention rate of the modified basalt fiber monofilament was 94.1%, the elastic modulus was 98.5 MPa, the surface roughness (Ra value) was 22.3 nm, the contact angle was 92°, and the interfacial bond strength with asphalt was 2.6 MPa.

[0048] Example 3

[0049] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 25°C and 240W for 30 minutes, rinsed with deionized water until neutral, and dried in an oven at 80°C for 2 hours.

[0050] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The mixture was ultrasonically dispersed at 360W for 45 minutes to form a reaction solution. The pretreated basalt fiber was immersed in the reaction solution and reacted in a water bath at 75℃ for 2.0 h. The reacted basalt fiber was then removed, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 2 h to obtain silanized basalt fiber.

[0051] Hydrophobic nano-SiO2 was added to an ethanol solution at a mass ratio of 1.6% (ethanol concentration was 90%), and the solution was ultrasonically dispersed at 360W for 45 min. 0.5% KH550 was added to adjust the pH to 6, and the solution was ultrasonically dispersed at 360W for 30 min to form a suspension. Silanized basalt fibers were immersed in the suspension and stirred in a 70℃ water bath for 2 h. The reacted silanized basalt fibers were then rinsed with anhydrous ethanol and dried in a 120℃ oven for 2 h to obtain modified basalt fibers.

[0052] Microstructure analysis:

[0053] As shown in Figure 3 and Figure 10 As shown, SEM observation revealed that the modified fiber surface exhibited cauliflower-like nanoprotrusions with a diameter of 50-100 nm, indicating a significant increase in roughness. FTIR spectroscopy showed a characteristic peak of Si-O-Si bonds at 1080 cm⁻¹, indicating successful grafting of the silane coupling agent and nano-SiO₂.

[0054] Performance tests of modified basalt fiber: The tensile strength of the modified basalt fiber monofilament was 97.6%, the elastic modulus was 104.6 MPa, the surface roughness (Ra value) was 24.7 nm, the contact angle was 95°, and the interfacial bond strength with asphalt was 2.8 MPa.

[0055] The modified basalt fibers were mixed with asphalt to form fiber-reinforced asphalt mixtures, and their performance was tested. The splitting tensile strength of the fiber-reinforced asphalt mixture increased by 21.46%, and the flexural strength increased by 12.7%. Three-dimensional network reinforcement: The modified basalt fibers formed a "bridging-adsorption-locking" structure in the asphalt, increasing the high-temperature dynamic stability of the fiber-reinforced asphalt mixture by 2.3 times and reducing the low-temperature creep stiffness by 30%. Crack inhibition effect: The microcrack initiation time of the fiber-reinforced asphalt mixture was prolonged by 30%, the propagation rate was reduced by 60%, and the fracture energy was increased by 2 times. UV aging tests showed that the penetration decay rate of the fiber-reinforced asphalt mixture decreased by 35%, and the softening point elevation decreased by 40%. After freeze-thaw cycles, the mass loss rate due to water damage decreased from 4.2% to 1.5%, and the anti-stripping performance was significantly improved.

[0056] Example 4

[0057] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 25°C and 240W for 30 minutes, rinsed with deionized water until neutral, and dried in an oven at 80°C for 2 hours.

[0058] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The mixture was ultrasonically dispersed at 360W for 45 minutes to form a reaction solution. The pretreated basalt fiber was immersed in the reaction solution and reacted in a water bath at 75℃ for 2 hours. The basalt fiber after the reaction was completed was taken out, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 2 hours to obtain silanized basalt fiber.

[0059] Hydrophobic nano-SiO2 was added to an ethanol solution at a mass ratio of 1.4% (90% ethanol concentration), and ultrasonically dispersed at 360W for 45 min. 0.5% KH550 was added to adjust the pH to 6, and then ultrasonically dispersed at 360W for 30 min to form a suspension. Silanized basalt fibers were immersed in the suspension and stirred in a 75℃ water bath for 2 h. The reacted silanized basalt fibers were then rinsed with anhydrous ethanol and dried in a 120℃ oven for 2 h to obtain modified basalt fibers.

[0060] SEM images of the prepared modified basalt fibers are shown below. Figure 4 As shown, the performance of modified basalt fiber was tested; the tensile strength retention rate of the modified basalt fiber monofilament was 94.5%, the elastic modulus was 97.3 MPa, the surface roughness (Ra value) was 21.1 nm, the contact angle was 90°, and the interfacial bond strength with asphalt was 2.5 MPa.

[0061] Example 5

[0062] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 300W for 30 minutes at 25℃, rinsed with deionized water until neutral, and dried in an oven at 80℃ for 2 hours.

[0063] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The mixture was ultrasonically dispersed at 400W for 30 minutes to form a reaction solution. The pretreated basalt fiber was immersed in the reaction solution and reacted in a water bath at 75℃ for 1.5 hours. The reacted basalt fiber was then removed, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 2 hours to obtain silanized basalt fiber.

[0064] Hydrophobic nano-SiO2 was added to an ethanol solution at a mass ratio of 1.8% (ethanol concentration was 90%), and the solution was ultrasonically dispersed at 400W for 30 min. 0.5% KH550 was added to adjust the pH to 6, and the solution was ultrasonically dispersed at 400W for 15 min to form a suspension. Silanized basalt fibers were immersed in the suspension and stirred in a 70℃ water bath for 2 h. The reacted silanized basalt fibers were then rinsed with anhydrous ethanol and dried in a 120℃ oven for 2 h to obtain modified basalt fibers.

[0065] SEM images of the prepared modified basalt fibers are shown below. Figure 5 As shown, the performance of modified basalt fiber was tested; the tensile strength of the modified basalt fiber monofilament was 95.7%, the elastic modulus was 99.4 MPa, the surface roughness (Ra value) was 24.1 nm, the contact angle was 94°, and the interfacial bond strength with asphalt was 2.7 MPa.

[0066] Example 6

[0067] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 25°C and 240W for 30 minutes, rinsed with deionized water until neutral, and dried in an oven at 80°C for 2 hours.

[0068] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The mixture was ultrasonically dispersed at 400W for 30 minutes to form a reaction solution. The pretreated basalt fiber was immersed in the reaction solution and reacted in a water bath at 75℃ for 2 hours. The basalt fiber after the reaction was completed was taken out, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 1 hour to obtain silanized basalt fiber.

[0069] Hydrophobic nano-SiO2 was added to an ethanol solution at a mass ratio of 1.8% (ethanol concentration was 90%), and the solution was ultrasonically dispersed at 400W for 30 min. 0.5% KH550 was added to adjust the pH to 6, and the solution was ultrasonically dispersed at 400W for 15 min to form a suspension. Silanized basalt fibers were immersed in the suspension and stirred in a 75℃ water bath for 2 h. The reacted silanized basalt fibers were then rinsed with anhydrous ethanol and dried in a 120℃ oven for 2 h to obtain modified basalt fibers.

[0070] SEM images of the prepared modified basalt fibers are shown below. Figure 6 As shown, the performance of modified basalt fiber was tested; the tensile strength of the modified basalt fiber monofilament was 96.3%, the elastic modulus was 102.4 MPa, the surface roughness (Ra value) was 24.5 nm, the contact angle was 94°, and the interfacial bond strength with asphalt was 2.8 MPa.

[0071] Comparative Example 1

[0072] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 240W for 30 minutes at 25℃, rinsed with deionized water until neutral, and dried in an oven at 80℃ for 2 hours.

[0073] SEM images of the prepared basalt fibers are shown below. Figure 7 As shown, the FTIR spectrum is as follows: Figure 10 As shown, the surface roughness (Ra value) of the basalt fiber monofilament is 1.41 nm, the contact angle is 72°, and the interfacial bond strength with asphalt is 1.2 MPa.

[0074] Comparative Example 2

[0075] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 25°C and 240W for 30 minutes, rinsed with deionized water until neutral, and dried in an oven at 80°C for 2 hours.

[0076] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The mixture was ultrasonically dispersed at 360W for 30 minutes to form a reaction solution. The pretreated basalt fiber was immersed in the reaction solution and reacted in a water bath at 75℃ for 2.0 hours. The reacted basalt fiber was then removed, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 1 hour to obtain silanized basalt fiber.

[0077] SEM images of the prepared basalt fibers are shown below. Figure 8 As shown, the surface roughness (Ra value) of silanized basalt fiber is 4.8 nm, the contact angle is 80°, and the interfacial bond strength with asphalt is 1.8 MPa.

[0078] Comparative Example 3

[0079] Basalt fibers were placed in acetone solution, ultrasonically cleaned at 25°C and 240W for 30 minutes, rinsed with deionized water until neutral, and dried in an oven at 80°C for 2 hours.

[0080] KH550 was dissolved in anhydrous ethanol at a volume ratio of 1:20, and glacial acetic acid was added to adjust the pH to 5. The solution was ultrasonically dispersed at 360W for 30 minutes to form a reaction solution. The pretreated basalt fibers were immersed in the reaction solution and reacted in a water bath at 70℃ for 2.0 h. The reacted basalt fibers were then removed, rinsed three times with anhydrous ethanol, and cured in an oven at 120℃ for 1 h to obtain silanized basalt fibers.

[0081] Nano-SiO2 was added to an ethanol solution at a mass ratio of 1.6% (90% ethanol concentration), and ultrasonically dispersed at 360W for 45 min. 0.5% KH550 was added to adjust the pH to 6, and then ultrasonically dispersed at 360W for 30 min to form a suspension. Silanized basalt fibers were immersed in the suspension and stirred in a 70℃ water bath for 2 h. The reacted silanized basalt fibers were then rinsed with anhydrous ethanol and dried in a 100℃ oven for 2 h to obtain modified basalt fibers.

[0082] SEM images of the prepared basalt fibers are shown below. Figure 9 As shown, the modified basalt fiber has a surface roughness (Ra value) of 18.2 nm, a contact angle of 85°, and an interfacial bond strength with asphalt of 2.1 MPa.

[0083] The Ra values ​​and contact angles of Examples 1-3 were significantly higher than those of the Comparative Examples, with an increase in interfacial bonding strength of 108%-142%, indicating that the synergistic modification of "silane + hydrophobic nano-SiO2" effectively constructed a three-dimensional structure. The Ra value of Comparative Example 2 (single silane) was only 4.8 nm, with limited improvement in bonding strength. Due to the strong hydrophilicity of nano-SiO2, the Ra value and hydrophobicity of Comparative Example 3 were insufficient, resulting in a lower improvement in bonding strength than the Examples.

Claims

1. A hydrophobic nano-silica modified basalt fiber, characterized in that, The method involves using basalt fiber as a matrix, grafting a silane coupling agent and hydrophobic nano-SiO2 onto the surface of the basalt fiber. The silane coupling agent is an amino-containing silane; the hydrophobic SiO2 is trimethylchlorosilane-modified gas-phase SiO2. The silane coupling agent forms Si-O-Si covalent bonds on the surface of the basalt fiber through hydrolysis and condensation, and the grafting is completed after introducing amino active sites. The hydrophobic nano-SiO2 is chemically bonded to the amino group of the silane coupling agent and physically adsorbed and anchored onto the surface of the basalt fiber, thus completing the grafting. The surface of the grafted basalt fiber exhibits micro- and nano-protrusions.

2. The hydrophobic nano-silica modified basalt fiber according to claim 1, characterized in that, The hydrophobic nano-SiO2 has a particle size of 20-50 nm and a surface hydroxyl content of <2 hydroxyl groups / nm².

3. The hydrophobic nano-silica modified basalt fiber according to claim 2, characterized in that, The silane coupling agent hydrolysis is achieved by dissolving the silane coupling agent in anhydrous ethanol to form a hydrolysis system. The volume ratio of the silane coupling agent to anhydrous ethanol is 1:20, and the pH value of the hydrolysis system is 5.

4. The hydrophobic nano-silica modified basalt fiber according to claim 3, characterized in that, The hydrophobic nano-SiO2 in the dispersion has a mass ratio of 1.4%-1.8%, and the dispersion also contains 0.5% silane coupling agent with a pH value of 6.

5. The hydrophobic nano-silica modified basalt fiber according to claim 4, characterized in that, The silane coupling agent used is KH550.

6. A method for preparing hydrophobic nano-silica modified basalt fiber according to any one of claims 1-5, characterized in that, Includes the following steps: Pretreatment of basalt fibers; The silane coupling agent is dissolved, the pH value is adjusted and ultrasonically dispersed to form a reaction solution. The pretreated basalt fiber is immersed in the reaction solution for water bath reaction. The basalt fiber after the reaction is completed is taken out, cleaned and dried to solidify to obtain silanized basalt fiber. Hydrophobic nano-SiO2 was added to a dispersion, ultrasonically dispersed, and the pH value was adjusted to form a suspension. Silanized basalt fibers were added to the suspension for a water bath reaction. The silanized basalt fibers that had completed the reaction were taken out, washed, and dried to obtain modified basalt fibers.

7. The method for preparing hydrophobic nano-silica modified basalt fiber according to claim 6, characterized in that, The pretreatment in step one specifically includes placing basalt fibers in an acetone solution, ultrasonically cleaning them, rinsing them with deionized water until neutral, and then drying them in an oven. The ultrasonic cleaning power is 200-300W, the time is 15-30 minutes, the oven temperature is 80℃, and the drying time is 2 hours.

8. The method for preparing hydrophobic nano-silica modified basalt fiber according to claim 7, characterized in that, The basalt fibers, after pretreatment, have a moisture content of ≤0.2%, a diameter of 9-15 μm, a length of 6-12 mm, and a surface hydroxyl exposure rate of ≥90%.

9. The method for preparing hydrophobic nano-silica modified basalt fiber according to claim 8, characterized in that, Step two specifically includes dissolving the silane coupling agent in anhydrous ethanol at a volume ratio of 1:20, adjusting the pH to 5 with glacial acetic acid, ultrasonically dispersing at 300-400W for 30-45 minutes to form a reaction solution, immersing the pretreated basalt fiber in the reaction solution, and shaking it in a water bath at 65-75℃ for 1-2 hours. After removing the pretreated basalt fiber, rinsing it with anhydrous ethanol, and then placing it in an oven at 120℃ for 1-2 hours to cure it, the silanized basalt fiber is obtained.

10. The method for preparing hydrophobic nano-silica modified basalt fiber according to claim 9, characterized in that, Step three specifically includes adding hydrophobic nano-SiO2 to an ethanol solution at a mass ratio of 1.4%-1.8% (ethanol solution concentration is 90%), ultrasonically dispersing at 300-400W for 30-45 minutes, adding 0.5% KH550 to adjust the pH to 6, and then ultrasonically dispersing at 300-400W for 15-30 minutes to form a suspension; immersing silanized basalt fibers in the suspension, stirring and reacting in a water bath at 65-75℃ for 1-2 hours, removing the reacted silanized basalt fibers, rinsing with ethanol, and drying in a 120℃ oven for 1-2 hours to obtain modified basalt fibers.

Images