Carbon nanotube modified glass fiber composite sound-absorbing material, preparation method and application thereof

Abstract

This invention relates to a composite sound-absorbing material based on carbon nanotube-modified glass fiber, its preparation method, and its application. The composite sound-absorbing material includes a glass fiber substrate, on the surface of which carbon nanotube micro / nanostructures are disposed, with silica microspheres loaded at the tips of the carbon nanotube micro / nanostructures; wherein the mass fraction of the carbon nanotube micro / nanostructures is 10%–60%. The problem this invention aims to solve is to achieve a multi-level micro / nano structure design by in-situ growing carbon nanotubes on the surface of glass fiber, thereby achieving low-frequency, broadband sound absorption effects.

Description

Technical Field

[0001] This invention relates to a composite sound-absorbing material based on carbon nanotube-modified glass fiber, its preparation method and application, belonging to the field of sound-absorbing material technology. Background Technology

[0002] Sound-absorbing materials have important applications in construction, transportation, and industrial noise reduction. In recent years, fiber-based composite materials have become the mainstream due to their lightweight, controllable porosity, and surface properties. Traditional materials such as glass fiber, polyester fiber, and wood fiber are widely used due to their lightweight and corrosion resistance. However, their sound absorption performance in the mid-to-low frequency range (≤2000Hz) is significantly insufficient, mainly relying on the physical control of material thickness and porosity, resulting in large material volume and high cost. In recent years, microstructure modification technology (such as nanomaterial composites) has become a research hotspot for improving sound absorption performance.

[0003] By designing appropriate microstructures for fiber materials, efficient dissipation of sound wave energy can be achieved. For example, molding fibers into hierarchical porous foam structures can effectively improve the impedance matching of the material when dealing with low-frequency noise, thereby enhancing the sound absorption effect. Developing fiber materials with core-shell structures and covering the surface of traditional inorganic fibers with functional nanolayers can increase the roughness of the material's internal surface, thereby enhancing the reflection of sound waves within the material and improving the sound absorption effect.

[0004] Although the emergence of new processes and theories in recent years has promoted the development of a large number of new fiber sound-absorbing materials, fiber-based sound-absorbing materials still face shortcomings such as complex processes, short lifespan, and environmental unfriendliness, and further research and development are needed to improve them. Summary of the Invention

[0005] In view of this, the main objective of the present invention is to provide a composite sound-absorbing material based on carbon nanotube-modified glass fiber, its preparation method and application. The problem to be solved is to achieve a micro-nano multi-level structure design by growing carbon nanotubes in situ on the surface of glass fiber, thereby achieving low-frequency and wide-frequency sound absorption effect.

[0006] The objective of this invention and the technical problem it solves are achieved by the following technical solution. This invention proposes a composite sound-absorbing material based on carbon nanotube-modified glass fiber. The composite sound-absorbing material includes a glass fiber substrate, on the surface of which carbon nanotube micro / nano structures are disposed, and the top of the carbon nanotube micro / nano structures is loaded with silica microspheres; wherein the mass fraction of the carbon nanotube micro / nano structures is 10%–60%.

[0007] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0008] Preferably, in the aforementioned composite sound-absorbing material based on carbon nanotube-modified glass fiber, the glass fiber substrate is selected from at least one of E-glass fiber, S-glass fiber, quartz fiber and high silica fiber, and its single filament diameter is 5-25 μm and its linear density is 100-9600 tex.

[0009] The objective of this invention and the technical problem it solves are achieved through the following technical solution. This invention proposes a method for preparing a composite sound-absorbing material based on carbon nanotube-modified glass fiber, comprising the following steps:

[0010] 1) Pretreatment: Immerse the glass fiber substrate or its fabric in hydrogen peroxide solution and treat it at 45-60℃ for 10-60 minutes to remove the sizing agent on the surface and form a hydroxyl activated layer;

[0011] 2) Supported catalyst: The pretreated fiber was impregnated in a complex colloidal solution and then dried under infrared lamp irradiation;

[0012] 3) Carbon nanotube growth: Using roll-to-roll chemical vapor deposition, the fiber carrying the catalyst is sequentially heated in the first heating stage and then heated in the second heating stage to grow carbon nanotubes in situ, thus obtaining the composite sound-absorbing material based on carbon nanotube-modified glass fiber.

[0013] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0014] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 1), the glass fiber substrate is in the form of a fabric, selected from plain weave fabric, non-woven fabric, or mesh fabric, with an areal density of 20–160 g / m². 2 .

[0015] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, the concentration of the hydrogen peroxide aqueous solution in step 1) is 10–30 wt%.

[0016] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 2), the complexed colloidal solution contains Ni(NO3)2·6H2O and Fe(NO3)3·9H2O, the total concentration of the two metal ions is 0.1-0.5 mol / L, and the pH value is 8-9.

[0017] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 2), the molar ratio of Ni to Fe in the complexed colloidal solution is 95:5 to 80:20.

[0018] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 2), the complexed colloidal solution further contains an ammonium citrate complexing agent with a concentration of 0.01–0.05 mol / L; the drying temperature is 60–100 °C, and the drying time is 9–11 min.

[0019] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 3), the conditions for the first heating are as follows: the temperature is 200–450°C, the atmosphere is a hydrogen-argon mixture with a hydrogen gas fraction of 0.1–5%, and the residence time is 0.5–5 min.

[0020] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 3), the conditions for the second heating are as follows: the temperature is 500–850°C, the atmosphere is an acetylene / argon mixture with an acetylene volume fraction between 0.05 and 4.5%, and the residence time is 0.5–5 min.

[0021] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 3), the linear velocity of the first heating and the second heating is both 0.2 to 2 m / min.

[0022] The objective of this invention and the technical problem it solves are achieved through the following technical solution. This invention proposes the application of a mid-to-low frequency noise absorbing material in noise shielding, wherein the mid-to-low frequency noise absorbing material is a composite sound-absorbing material made of carbon nanotubes modified with glass fibers, as described above.

[0023] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0024] Preferably, the aforementioned low-to-medium frequency noise absorbing material is used in noise shielding, wherein the noise shielding is architectural noise shielding, traffic noise shielding, or industrial noise shielding.

[0025] Preferably, in the application of the aforementioned low-to-medium frequency noise absorbing material in noise shielding, the low-to-medium frequency is 100 to 2000 Hz.

[0026] By employing the above technical solution, the composite sound-absorbing material based on carbon nanotube-modified glass fiber, its preparation method, and its application provided by the present invention have at least the following advantages:

[0027] This invention addresses the problem of insufficient low-frequency sound absorption performance in current foam-based sound-absorbing materials by proposing a method for preparing sound-absorbing materials based on carbon nanotube-modified glass fibers. By growing carbon nanotube micro-nano structures on the surface of traditional glass fibers, the low-frequency sound absorption performance of the material is improved and the sound absorption frequency band is broadened.

[0028] The material preparation method of the present invention is simple, does not involve complex processes and equipment (such as electrospinning, freeze drying, etc.), is easy to scale up and customize, and has controllable performance;

[0029] The preparation method proposed in this invention is compatible with most commercially available glass fiber types and specifications, and other raw materials are also simple and readily available, making it highly versatile.

[0030] The material prepared by this invention contains no organic components, is non-flammable, and is safe and eco-friendly in use and disposal.

[0031] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the following describes a preferred embodiment of the present invention with a concentration of 0.01 to 0.05 mol / L; the drying temperature is 60 to 100°C and the time is 9 to 11 min.

[0032] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 3), the conditions for the first heating are as follows: the temperature is 200–450°C, the atmosphere is a hydrogen-argon mixture with a hydrogen gas fraction of 0.1–5%, and the residence time is 0.5–5 min.

[0033] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 3), the conditions for the second heating are as follows: the temperature is 500–850°C, the atmosphere is an acetylene / argon mixture with an acetylene volume fraction between 0.05 and 4.5%, and the residence time is 0.5–5 min.

[0034] Preferably, in the aforementioned method for preparing composite sound-absorbing materials based on carbon nanotube-modified glass fibers, in step 3), the linear velocity of the first heating and the second heating is both 0.2 to 2 m / min.

[0035] The objective of this invention and the technical problem it solves are achieved through the following technical solution. This invention proposes the application of a mid-to-low frequency noise absorbing material in noise shielding, wherein the mid-to-low frequency noise absorbing material is a composite sound-absorbing material made of carbon nanotubes modified with glass fibers, as described above.

[0036] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0037] Preferably, the aforementioned low-to-medium frequency noise absorbing material is used in noise shielding, wherein the noise shielding is architectural noise shielding, traffic noise shielding, or industrial noise shielding.

[0038] Preferably, in the application of the aforementioned low-to-medium frequency noise absorbing material in noise shielding, the low-to-medium frequency is 100 to 2000 Hz.

[0039] By employing the above technical solution, the composite sound-absorbing material based on carbon nanotube-modified glass fiber, its preparation method, and its application provided by the present invention have at least the following advantages:

[0040] This invention addresses the problem of insufficient low-frequency sound absorption performance in current foam-based sound-absorbing materials by proposing a method for preparing sound-absorbing materials based on carbon nanotube-modified glass fibers. By growing carbon nanotube micro-nano structures on the surface of traditional glass fibers, the low-frequency sound absorption performance of the material is improved and the sound absorption frequency band is broadened.

[0041] The material preparation method of the present invention is simple, does not involve complex processes and equipment (such as electrospinning, freeze drying, etc.), is easy to scale up and customize, and has controllable performance;

[0042] The preparation method proposed in this invention is compatible with most commercially available glass fiber types and specifications, and other raw materials are also simple and readily available, making it highly versatile.

[0043] The material prepared by this invention contains no organic components, is non-flammable, and is safe and eco-friendly in use and disposal.

[0044] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0045] Figure 1 This is a scanning electron microscope image of the composite sound-absorbing material sample of Example 5 of the present invention;

[0046] Figure 2 This is a scanning electron microscope image of the composite sound-absorbing material sample of Example 7 of the present invention;

[0047] Figure 3 This is a scanning electron microscope image of the composite sound-absorbing material sample of Example 12 of the present invention;

[0048] Figure 4 This is a scanning electron microscope image of the composite sound-absorbing material sample of Example 16 of the present invention. Detailed Implementation

[0049] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following detailed description, in conjunction with preferred embodiments, provides a detailed explanation of the specific implementation methods, structures, features, and effects of a composite sound-absorbing material based on carbon nanotube-modified glass fiber, its preparation method, and its application. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0050] Unless otherwise specified, all materials or reagents listed below are commercially available.

[0051] Some embodiments of the present invention provide a composite sound-absorbing material based on carbon nanotube-modified glass fiber. The composite sound-absorbing material includes a glass fiber substrate, on the surface of which a carbon nanotube micro / nanostructure is disposed, and silica microspheres are loaded at the tips of the carbon nanotube micro / nanostructure. The mass fraction of the carbon nanotube micro / nanostructure is 10%–60%. Below 10%, the CNT content on the fiber surface is too low, failing to generate sufficient microscopic "roughness," which is detrimental to sound absorption. Above 60%, the CNTs will entangle and aggregate, forming new interfaces, leading to the closure of the micropores with sound-absorbing properties, which is also detrimental to sound absorption.

[0052] In some optional embodiments, the glass fiber substrate is selected from at least one of alkali-free glass fiber (E-glass fiber), S-glass fiber, quartz fiber, or high-silica fiber, with a single filament diameter of 5–25 μm and a linear density of 100–9600 tex. The reason for limiting the diameter and linear density is that excessively fine single filament diameter and low linear density result in insufficient fiber strength to withstand the tensile stress applied during continuous processing, while excessively thick single filament diameter and high linear density lead to insufficient fiber flexibility and inability to adapt to the winding, unwinding, and weaving processes required for continuous processing. The fiber fabric can be plain weave, non-woven fabric, mesh fabric, etc., with a fabric areal density ranging from 20–160 g / m². 2 The reason for the limitation on surface density is that the lower the surface density, the greater the porosity of the fiber fabric. Too high porosity will make the sound-absorbing material too thick, which is not conducive to practical applications. On the other hand, too low porosity will prevent sound waves from entering the interior of the material, resulting in insufficient sound absorption performance.

[0053] Some embodiments of the present invention also provide a method for preparing a composite sound-absorbing material based on carbon nanotube-modified glass fiber, comprising the following steps:

[0054] 1) Pretreatment: Immerse the glass fiber substrate or its fabric in a 10-30 wt% hydrogen peroxide solution and treat it at 45-60℃ for 10-60 minutes to remove the sizing agent on the surface and form a hydroxyl activated layer. The fiber pretreatment process is mainly determined by the fiber's physical parameters and chemical composition. Generally speaking, the finer the monofilament and the higher the linear density, the more sizing agent the fiber contains. Therefore, a higher hydrogen peroxide concentration, temperature and longer treatment time are required to completely remove the sizing agent. However, excessively high temperatures and concentrations can cause oxidative damage to the fibers. If stronger oxidation conditions are required, the oxidation time can be extended to no more than 60 minutes, but optimal conditions do not recommend exceeding 30 minutes. Furthermore, the fiber's chemical composition (especially its SiO2 content) also determines the fiber pretreatment process parameters. The main purpose of pretreatment is to remove the sizing agent and fully expose surface hydroxyl groups. Higher SiO2 content exposes more dangling hydroxyl groups. A concentration below 10 wt% cannot provide sufficient oxidizing power, resulting in incomplete treatment. Excessively high concentrations damage the fiber itself and increase costs. 30 wt% is a common commercially available concentration of hydrogen peroxide and has sufficient oxidizing power, so this concentration is chosen as the upper limit. 45℃ and 10 minutes are the lower limit for oxidation treatment. Below this limit, incomplete removal of the sizing agent will occur. Excessive heating (above 60℃) or extending the time (above 60 minutes) increases costs and carries the risk of damaging the fiber itself. Therefore, the upper limit is set at 60℃ and 60 minutes.

[0055] 2) Catalyst Support: The pretreated fibers are impregnated in a complexed colloidal solution containing Ni(NO3)2·6H2O and Fe(NO3)3·9H2O, with a total metal ion concentration of 0.1–0.5 mol / L and pH = 8–9. After the fibers are completely submerged, they are filtered and dried. A pH below 0.1 mol / L results in insufficient metal loading and incomplete impregnation, while a pH above 0.5 mol / L causes metal agglomeration during subsequent processing. The purpose of pH control is to form complex molecules between Ni and Fe metals and the complexing agent. The formed complex molecules have suitable steric hindrance, allowing the metal to spread evenly on the fiber surface. pH = 8–9 is the range in which Ni, Fe, and ammonium citrate can stably complex. If the pH is too low, Ni and Fe exist in ionic form, resulting in too little steric hindrance and agglomeration. If the pH is too high, Ni and Fe exist in precipitated form, resulting in excessive steric hindrance and uneven distribution. The specific process is as follows: ① Nickel nitrate (Ni(NO3)2·6H2O) and iron nitrate (Fe(NO3)3·9H2O) are dissolved in deionized water at a certain Ni:Fe molar ratio, so that the total concentration of metal ions is between 0.1-0.5 mol / L and the Ni:Fe molar ratio is between 95:5-80:20. The Ni:Fe molar ratio affects the catalyst activity and determines the content and morphology of subsequent carbon nanotube growth. The main mechanism is that the precipitation degree of C element in Ni and Fe metals is different. The higher the Fe content, the faster the C precipitation. However, excessive Fe content will also lead to the precipitation of impurity C, reducing the crystallinity and uniformity of carbon nanotubes. Insufficient Fe content will lead to insufficient C precipitation, and the growth of carbon nanotubes will be inhibited. ② Add ammonium citrate complexing agent at a concentration between 0.01-0.05 mol / L. Then adjust the solution to pH 8-9 using sodium hydroxide, ammonia, etc., so that the catalyst forms a stable metal complex colloid. ③ Completely immerse the fiber in the solution to ensure that the catalytic metal ions uniformly cover the surface through chemical adsorption. Then dry the fiber under infrared lamp irradiation at 60-100℃ for 9-11 minutes. If the time is too short (e.g., less than 9 minutes) or the temperature is too low (e.g., less than 60℃), the drying will be incomplete. If the time is too long (e.g., more than 11 minutes) or the temperature is too high (e.g., more than 100℃), it will increase energy consumption and may also cause material oxidation. The resulting glass fiber or glass fiber fabric loaded with the catalyst is obtained.

[0056] 3) Carbon nanotube growth: A roll-to-roll chemical vapor deposition method was used to grow carbon nanotubes in situ by sequentially passing catalyst-loaded fibers through a first heating chamber and a second heating chamber. As the carbon nanotube content increased, its microstructure gradually transitioned from independent tubular structures to a felt-like structure. Figures 2 to 3 It can be seen that, Figure 2 It is tubular. Figure 3It is felt-like, with the content increasing from 40wt% to 60wt%. The specific growth process is as follows: ① Using a stepper motor for uniform speed traction, the fiber or fiber fabric is passed through the first heating chamber, where it stays for 0.5-5 minutes. The first heating chamber plays a role in reducing the metal; if the time is less than 0.5 minutes, the reduction is incomplete, and if it is more than 5 minutes, it will cause agglomeration. The temperature of the heating chamber is 200-450℃. The first heating chamber plays a role in reducing the metal; if the temperature is less than 200℃, reduction is not possible, and if it is more than 450℃, it will cause agglomeration. A hydrogen-argon mixture with a hydrogen gas fraction between 0.1% and 5% (v / v) is introduced. If the hydrogen gas fraction is less than 0.1%, the reduction will be too low, and if it is more than 5%, there will be a risk of combustion and explosion. ② Subsequently, the fiber or fiber fabric is passed through the second heating chamber at the same linear speed, where it stays for 0.5-5 minutes. The carbon nanotube content is basically determined by the residence time of the fiber in the second heating chamber. To obtain carbon nanotubes with a content between 10 and 60 wt%, the heating time was set between 0.5 and 5 minutes. The temperature of the second heating chamber was 500-850℃. The second heating chamber serves to grow carbon nanotubes on the fiber surface. Below 500℃, the main product is amorphous carbon; above 850℃, the fiber will be damaged. An acetylene / argon mixture with a volume fraction between 0.05% and 4.5% (v / v) is introduced. If the acetylene volume fraction is less than 0.05%, the carbon source supply will be too low, and carbon nanotubes will not grow. If the acetylene volume fraction is greater than 4.5%, uncontrollable carbon deposition will occur, affecting material performance and clogging the equipment. Tetraethyl orthosilicate silicon source gas can also be introduced to generate SiO2 microspheres on the top of the carbon nanotubes, expanding the broadband sound absorption effect. After growth, the material is naturally cooled to obtain carbon nanotube-modified glass fibers.

[0057] In some optional embodiments, in step 1), the glass fiber substrate is in the form of a fabric, selected from plain weave, nonwoven fabric, or mesh fabric, wherein the fabric porosity matches the areal density, and the areal density is 20–160 g / m². 2 .

[0058] In some optional embodiments, in step 2), the surface of the carbon nanotubes is further loaded with silica microspheres, which are simultaneously generated in the second heating chamber by introducing tetraethyl orthosilicate (5–10 sccm). Below a flow rate of 5 sccm, the tetraethyl orthosilicate concentration cannot be sufficient, resulting in incomplete silica microspheres. Furthermore, to avoid the decomposition of tetraethyl orthosilicate poisoning the catalyst (the formed silica may cover the catalyst surface, preventing it from contacting acetylene), the upper limit is set at 10 sccm.

[0059] In some optional embodiments, in step 2), the complexing colloidal solution further comprises ammonium citrate as a complexing agent at a concentration of 0.01–0.05 mol / L. Ammonium citrate is a key component of the complexing agent. Excessive concentration (e.g., greater than 0.05 mol / L) leads to an overabundance of complexing agent, increasing costs and introducing unnecessary component contamination. Insufficient concentration (e.g., less than 0.01 mol / L) results in incomplete metal complexation, failing to uniformly cover the glass fiber surface through chemisorption.

[0060] In some optional embodiments, in step 2), the Ni:Fe molar ratio of the complexed colloidal solution is 95:5 to 80:20. The Ni:Fe ratio affects the catalyst activity and determines the content and morphology of subsequent carbon nanotube growth. The main mechanism is that the precipitation degree of C element in Ni and Fe metals is different. The higher the Fe content, the faster the C precipitation. However, excessive Fe content will also lead to the precipitation of impurity C, reducing the crystallinity and uniformity of carbon nanotubes. Insufficient Fe content will lead to insufficient C precipitation, thus inhibiting carbon nanotube growth.

[0061] In some optional embodiments, in step 3), the linear velocity of the first heating chamber and the second heating chamber is 0.2–2 m / min, and the residence time of the fiber in the heating chamber is matched with the length of the chamber. Selecting a linear velocity range of 0.2–2 m / min results in a smaller error.

[0062] Some embodiments of the present invention also provide an application of carbon nanotube-modified glass fiber in the field of low-frequency sound absorption, wherein the material can be used for the absorption of low-to-medium frequency noise (100-2000Hz) in building, transportation, or industrial equipment.

[0063] The specific embodiments of the present invention will be described in further detail below with reference to examples, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention still fall within the scope of protection of the present invention.

[0064] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0065] This paper presents a method for preparing carbon nanotube-modified glass fiber low-frequency sound-absorbing materials with a carbon nanotube mass fraction ranging from 10% to 60% in the total mass of the material, using commercially available glass fiber filaments. The glass fibers used include alkali-free glass fiber (E-glass fiber), S-glass fiber, quartz fiber, and high-silica fiber. The diameter of the individual fiber filaments ranges from 5 to 25 μm, and the linear density ranges from 100 to 9600 tex.

[0066] Example 1

[0067] Alkali-free glass fibers were treated with hydrogen peroxide oxidation to remove the sizing agent on their surface. Specifically, the fibers were soaked in a 10wt% H2O2 solution at 55°C for 30 minutes to oxidize and remove the silane coupling agent residue on the surface, forming a hydroxyl activated layer. The fibers were then washed with deionized water until neutral to obtain the pretreated fibers.

[0068] The pretreated fibers are wound onto a spool and pulled by a stepper motor through a catalyst solution tank. The specific process is as follows: ① Ni(NO3)2·6H2O and Fe(NO3)3·9H2O are dissolved in deionized water at a molar ratio of Ni:Fe = 95:5, so that the total concentration of metal ions is 0.1 mol / L; ② Ammonium citrate complexing agent is added at a concentration of 0.01 mol / L, and then 28 wt% ammonia water is used to adjust the solution to pH = 8 so that the catalyst forms a stable metal complex colloid; ③ The fibers are completely immersed in the above metal complex colloidal solution for 30 seconds to ensure that the catalytic metal ions uniformly cover the surface through chemical adsorption, and then the fibers are dried under infrared lamp irradiation at 60°C for 10 minutes to obtain glass fibers loaded with catalyst.

[0069] Carbon nanotubes were grown from the aforementioned catalyst-loaded glass fibers using roll-to-roll chemical vapor deposition (RTR-CVD). Under the constant traction of a stepper motor at 1 m / min, the fibers were sequentially passed through the first and second heating chambers, allowing the carbon nanotubes to grow in situ on the glass fiber surface. The specific growth process was as follows: ① Under the traction of the stepper motor, the catalyst-loaded glass fibers were passed through the first heating chamber, where they remained for 0.5 min; the heating chamber temperature was 200°C, and the gas atmosphere was a 0.5% (v / v) hydrogen-argon mixture; ② Subsequently, the fibers that had passed through the first heating chamber were passed through the second heating chamber, where they remained for 0.5 min; the heating chamber temperature was 500°C, and the gas atmosphere was a 0.5% (v / v) acetylene / argon mixture. After natural cooling to room temperature, a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 10 wt% was obtained, named CNT / e-GF-10%.

[0070] Example 2

[0071] The difference between this embodiment and Embodiment 1 is that in this embodiment, the temperature of the second heating chamber is 850°C during the roll-to-roll chemical vapor deposition process. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 12 wt%, named CNT / e-GF-12%.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that the temperature of the second heating chamber in this comparative example is 900°C during the roll-to-roll chemical vapor deposition process. This comparative example ultimately yielded a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 15 wt%, named CNT / e-GF-15%. The tensile strength of the products obtained in Examples 1, 2, and Comparative Example 1 was tested, and the results are shown in Table 1.

[0074] Table 1. Fiber parameters and applications of Examples 1-2 and Comparative Example 1.

[0075]

[0076] As can be seen from the data in Table 1, Examples 1-2 and Comparative Example 1 mainly compared the effects of parameters in the second heating chamber (temperature zone 2) on carbon nanotube growth. Carbon-containing gas undergoes cracking and precipitation on the catalyst surface, growing into carbon nanotubes. By changing the growth temperature and acetylene concentration, low-frequency sound-absorbing materials with different carbon nanotube contents can be obtained. A comparison of Examples 1 and 2 shows that, due to the higher second heating chamber temperature used in Example 2, while achieving a higher carbon nanotube content, the fiber tensile strength also decreased slightly. With further increases in temperature, as shown in Comparative Example 1, when the growth temperature in the second heating chamber exceeds the softening point of alkali-free glass fiber (850℃), although a higher carbon nanotube content can still be obtained, the mechanical properties of the material will be significantly reduced, thus hindering its subsequent applications.

[0077] Example 3

[0078] S-glass fibers were treated with hydrogen peroxide oxidation to remove the sizing agent on their surface. Specifically, the fibers were soaked in a 12wt% H2O2 solution at 45°C for 10 minutes to oxidize and remove the silane coupling agent residue on the surface, forming a hydroxyl activated layer. The fibers were then washed with deionized water until neutral to obtain the pretreated fibers.

[0079] The pretreated fibers are wound onto a spool and pulled by a stepper motor through a catalyst solution tank. The specific process is as follows: ① Ni(NO3)2·6H2O and Fe(NO3)3·9H2O are dissolved in deionized water at a molar ratio of Ni:Fe = 90:10, so that the total concentration of metal ions is 0.2 mol / L; ② Ammonium citrate complexing agent is added at a concentration of 0.02 mol / L, and then 28 wt% ammonia water is used to adjust the solution to pH = 9 so that the catalyst forms a stable metal complex colloid; ③ The fibers are completely immersed in the above metal complex colloidal solution for 30 seconds to ensure that the catalytic metal ions uniformly cover the surface through chemical adsorption. Then, the fibers are dried under infrared lamp irradiation at 100°C for 10 minutes to obtain glass fibers loaded with catalyst.

[0080] Carbon nanotubes were grown from the aforementioned glass fiber loaded with catalyst using roll-to-roll chemical vapor deposition (RTR-CVD). Under the constant traction of a stepper motor at 1 m / min, the fiber is sequentially passed through the first and second heating chambers, allowing carbon nanotubes to grow in situ on the glass fiber surface. The specific growth process is as follows: ① Under the traction of the stepper motor, the glass fiber carrying the catalyst is passed through the first heating chamber, where it stays for 2 minutes; the heating chamber temperature is 300℃, and the gas atmosphere is a 1.5% (v / v) hydrogen-argon mixture (where 1.5% (v / v) is the hydrogen content in the mixture); ② Subsequently, the fiber passing through the first heating zone is passed through the second heating chamber, where it stays for 1 minute; the heating chamber temperature is 600℃, and the gas atmosphere is a 2% (v / v) acetylene / argon mixture (where 2% (v / v) is the acetylene content in the mixture). After natural cooling to room temperature, a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 25 wt% is obtained, named CNT / s-GF-25%.

[0081] Example 4

[0082] The difference between this embodiment and Embodiment 3 is that, in this embodiment, the fiber residence time in the second heating chamber during the roll-to-roll chemical vapor deposition process is 1.5 minutes. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 18 wt%, named CNT / s-GF-18%.

[0083] Example 5

[0084] The difference between this embodiment and Embodiment 3 is that in this embodiment, the fiber stays in the second heating chamber for 3 minutes during the roll-to-roll chemical vapor deposition process. The final result is a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 24 wt%, named CNT / s-GF-24%.

[0085] Example 6

[0086] The difference between this embodiment and Embodiment 3 is that in this embodiment, the fiber stays in the second heating chamber for 5 minutes during the roll-to-roll chemical vapor deposition process. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 30 wt%, named CNT / s-GF-30%.

[0087] As can be seen from the results of Examples 3-6, as the residence time of the fiber in the second heating chamber is extended, the proportion of carbon nanotubes in the material gradually increases. Under the conditions of catalyst concentration of 0.2 mol / L and composition of Fe:Ni = 90:10, the carbon nanotube content can reach up to 30 wt%.

[0088] Example 7

[0089] The difference between this embodiment and Example 6 is that the catalyst concentration in this embodiment is 0.4 mol / L, while the other conditions are the same as in Example 6. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 40 wt%, named CNT / s-GF-40%.

[0090] Example 8

[0091] The difference between this embodiment and Example 6 is that the catalyst concentration in this embodiment is 0.5 mol / L, while the other conditions are the same as in Example 6. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 50 wt%, named CNT / s-GF-50%.

[0092] Example 9

[0093] The difference between this embodiment and Example 8 is that the molar ratio of Fe:Ni catalyst in this embodiment is 85:15, otherwise it is the same as in Example 8. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 54 wt%, named CNT / s-GF-54%.

[0094] Example 10

[0095] The difference between this embodiment and Example 8 is that the Fe:Ni molar ratio of the catalyst in this embodiment is 80:20, while the rest is the same as in Example 8. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 60 wt%, named CNT / s-GF-60%.

[0096] Example 11

[0097] The difference between this embodiment and Embodiment 9 is that the gas atmosphere of the second heating chamber in this embodiment is a 2.5% (v / v) acetylene / argon mixture, otherwise it is the same as in Embodiment 9. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 60 wt%, named CNT / s-GF-56%.

[0098] Example 12

[0099] The difference between this embodiment and Embodiment 9 is that the gas atmosphere of the second heating chamber in this embodiment is a 5% (v / v) acetylene / argon mixture, otherwise it is the same as in Embodiment 9. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 60 wt%, named CNT / s-GF-60%.

[0100] The results of Examples 7 and 8 show that increasing the catalyst concentration can further increase the carbon nanotube content in the material.

[0101] The results of Examples 9 and 10 show that increasing the Ni content in the catalyst can further increase the carbon nanotube content in the material.

[0102] The results of Examples 9, 11, and 12 show that, without changing the catalyst composition and concentration, the carbon nanotube content in the material can be further increased by adjusting the atmosphere in the second heating chamber.

[0103] The results of Examples 1-12 show that the carbon nanotube content in low-frequency sound-absorbing materials can be controlled by adjusting the catalyst composition, concentration, and parameters such as temperature, time, and atmosphere in the second heating zone.

[0104] Based on the above method, carbon nanotubes can also be modified on the surface of glass fiber fabrics (such as non-woven fabrics, plain weave fabrics, and mesh fabrics). Through similar processes, low-frequency sound-absorbing materials with a carbon nanotube mass fraction distribution between 10% and 60% can be obtained.

[0105] Based on the above method, an appropriate amount of tetraethyl orthosilicate silicon source gas can be introduced into the second heating chamber to form silica microspheres at the top of the carbon nanotubes, thereby further extending the sound absorption frequency band of the low-frequency sound-absorbing material. The specific method is as follows.

[0106] Example 13

[0107] S-glass fibers were treated with hydrogen peroxide oxidation to remove the sizing agent on their surface. Specifically, the fibers were soaked in a 30wt% H2O2 solution at 60°C for 60 minutes to oxidize and remove the silane coupling agent residue on the surface, forming a hydroxyl activated layer. The fibers were then washed with deionized water until neutral to obtain the pretreated fibers.

[0108] The pretreated fibers are wound onto a spool and pulled by a stepper motor through a catalyst solution tank. The specific process is as follows: ① Ni(NO3)2·6H2O and Fe(NO3)3·9H2O are dissolved in deionized water at a molar ratio of Ni:Fe = 90:10, so that the total concentration of metal ions is 0.2 mol / L; ② Ammonium citrate complexing agent is added at a concentration of 0.02 mol / L, and then 28 wt% ammonia water is used to adjust the solution to pH = 9 so that the catalyst forms a stable metal complex colloid; ③ The fibers are completely immersed in the above metal complex colloidal solution for 30 seconds to ensure that the catalytic metal ions uniformly cover the surface through chemical adsorption, and then the fibers are dried under infrared lamp irradiation at 100°C for 10 minutes to obtain glass fibers loaded with catalyst.

[0109] Carbon nanotubes were grown from the aforementioned glass fiber loaded with catalyst using roll-to-roll chemical vapor deposition (RTR-CVD). Under the traction of a stepper motor, the fiber is sequentially passed through the first and second heating chambers, allowing carbon nanotubes to grow in situ on the glass fiber surface. The specific growth process is as follows: ① Under the traction of a stepper motor, the glass fiber carrying the catalyst is passed through the first heating chamber, where it stays for 2 minutes; the heating chamber temperature is 300℃, and the gas atmosphere is a 1.5% (v / v) hydrogen-argon mixture (where 1.5% (v / v) is the hydrogen content in the mixture); ② Subsequently, the fiber passing through the first heating zone is passed through the second heating chamber, where it stays for 1 minute; the heating chamber temperature is 600℃, and the gas atmosphere is a 2% (v / v) acetylene / argon mixture (where 2% (v / v) is the acetylene content in the mixture), while 5 sccm of tetraethyl orthosilicate is introduced. After natural cooling to room temperature, a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 22 wt% is obtained, named SiO2@CNT / s-GF-22%.

[0110] Example 14

[0111] The difference between this embodiment and Embodiment 13 is that in this embodiment, 10 sccm of tetraethyl orthosilicate is introduced into the second heating chamber. After natural cooling to room temperature, a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 18 wt% is obtained, named SiO2@CNT / s-GF-18%.

[0112] Example 15

[0113] The difference between this embodiment and Embodiment 12 is that in this embodiment, 10 sccm of tetraethyl orthosilicate is introduced into the second heating chamber. After natural cooling to room temperature, a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 55 wt% is obtained, named SiO2@CNT / s-GF-55%.

[0114] Example 16

[0115] The difference between this embodiment and Example 15 is that the molar ratio of Fe to Ni in this embodiment is 80:20. This embodiment ultimately yields a low-frequency sound-absorbing material with a carbon nanotube mass fraction of 60 wt%, named SiO2@CNT / s-GF-60%.

[0116] A comparison of Examples 13 and 14, and Examples 12 and 15, shows that increasing the amount of tetraethyl orthosilicate inhibits the formation of carbon nanotubes to some extent. This is because the formed silica may cover the surface of the catalyst, preventing it from contacting acetylene. However, the results of Example 16 indicate that by appropriately adjusting the catalyst composition, the tendency for silica to cover the catalyst surface can be reduced, thereby ensuring the formation of 60 wt% carbon nanotubes.

[0117] Low-frequency sound absorption tests were conducted on the materials from Examples 5, 7, 12, and 16. The test method was as follows: First, the fiber was made into a circular sample with a diameter of 100 mm, matching the inner diameter of the standing wave tube. The sample was installed at the end of the standing wave tube, with the back tightly against a rigid backing to avoid the cavity affecting the test results. Then, a loudspeaker was selected and excited to emit sound waves of 200 Hz, 500 Hz, 1000 Hz, 1500 Hz, and 2000 Hz. After the sound waves were reflected by the sample, a stable standing wave was formed inside the standing wave tube. The position of the detector was changed to test the sound pressure at different positions inside the tube. The maximum (Lmax) and minimum (Lmin) sound pressure within one cycle were measured and substituted into the following formula to calculate the sound absorption coefficient α.

[0118]

[0119] Where SWR is the standing wave ratio, SWR=10^[(L max -L min The test was conducted three times at each frequency point, and the arithmetic mean was taken as the sound absorption coefficient at that point. The test results are summarized in Table 2.

[0120] Table 2 Sound absorption performance of Examples 5, 7, 12, and 16 at different frequencies

[0121] Example 200Hz 500Hz 1000Hz 1500Hz 2000Hz CNT content Example 5 0.11 0.34 0.68 0.66 0.59 24wt% Example 7 0.15 0.47 0.95 0.93 0.84 40wt% Example 12 0.15 0.43 0.84 0.86 0.85 60wt% Example 16 0.32 0.54 0.98 0.97 0.89 60wt%

[0122] As can be seen from Examples 5, 7, 12, and 16 in Table 2, the composite sound-absorbing material based on carbon nanotube-modified glass fiber proposed in this invention exhibits good sound absorption performance in the mid-to-low frequency range. The results of Examples 5, 7, and 12 show that as the carbon nanotube content increases from 24% to 60%, the sound absorption performance first increases and then decreases. This is mainly because as the carbon nanotube content increases, the carbon nanotubes become entangled on the fiber surface, forming pore structures of different sizes, increasing the tortuosity of sound waves passing through the fiber surface, thus leading to increased sound wave energy attenuation. However, as the carbon nanotube content further increases, the carbon nanotubes will compress each other, forming a "felt-like" morphology (see...). Figure 3 The closure of micropores with sound-absorbing properties due to the carbon nanotubes reduces the material's sound absorption capacity. Therefore, the sound absorption effect of composite sound-absorbing materials obtained by simply modifying carbon nanotubes has an upper limit. Example 16, based on Example 12, further generates silica microspheres at the top of the carbon nanotubes, which further improves the specific surface area and porosity of the composite sound-absorbing material. A new sound wave loss mechanism is introduced through the carbon-silicon interface, thereby improving both the peak sound absorption coefficient and the low-frequency sound absorption coefficient of the composite sound-absorbing material. The peak sound absorption coefficient reaches 0.98 at 1000Hz, and the low-frequency (200Hz, 500Hz) sound absorption coefficients are 0.32 and 0.54, respectively, representing increases of 113% and 14.9%, respectively, showing a significant improvement.

[0123] from Figure 1-3 It can be seen that as the carbon nanotube content increases, the carbon nanotubes gradually become entangled and eventually form a felt. Figure 4 Is Figure 3 Based on this, silica microspheres are grown, which further improves the specific surface area and porosity of the composite sound-absorbing material.

[0124] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0125] The numerical range described in this invention includes all values ​​within this range, and also includes any range value composed of any two values ​​within this range. Different values ​​of the same indicator appearing in all embodiments of this invention can be arbitrarily combined to form a range value.

[0126] The technical features in the claims and / or specification of this invention can be combined, and the combination is not limited to the combinations obtained through reference in the claims. Technical solutions obtained by combining the technical features in the claims and / or specification are also within the scope of protection of this invention.

[0127] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a composite sound-absorbing material based on carbon nanotube-modified glass fiber, characterized in that, Includes the following steps: 1) Pretreatment: Immerse the glass fiber substrate or its fabric in a 10-30 wt% hydrogen peroxide solution and treat it at 45-60℃ for 10-60 minutes to remove the surface sizing agent and form a hydroxyl activated layer; 2) Supported catalyst: The pretreated fibers are impregnated with a catalyst containing... and In the complexed colloidal solution, the molar ratio of Ni to Fe is 95:5~80:20, and then it is dried under infrared lamp irradiation at 60~100℃ for 9-11 min; 3) Carbon nanotube growth: A roll-to-roll chemical vapor deposition method is used to sequentially pass the catalyst-loaded fibers through: The first heating is performed at a temperature of 200~450℃, using a hydrogen-argon mixture with a hydrogen gas fraction of 0.1~5%, and the mixture is held for 0.5~5 minutes. The second heating is carried out at a temperature of 500~850℃, with an acetylene / argon mixture containing 0.05~4.5% acetylene by volume, and 5~10 sccm of tetraethyl orthosilicate is introduced to simultaneously generate silica microspheres at the top of the carbon nanotubes, and the mixture is held for 0.5~5 min. The composite sound-absorbing material based on carbon nanotube-modified glass fiber was obtained.

2. The method for preparing the composite sound-absorbing material based on carbon nanotube-modified glass fiber as described in claim 1, characterized in that, In step 1), the glass fiber substrate is in the form of a fabric, selected from plain weave fabric, non-woven fabric, or mesh fabric, with an areal density of 20~160. .

3. The method for preparing the composite sound-absorbing material based on carbon nanotube-modified glass fiber as described in claim 1, characterized in that, In step 2), the total concentration of metal ions in the complexed colloidal solution is 0.1~0.5 mol / L, and the pH value is 8~9.

4. The method for preparing the composite sound-absorbing material based on carbon nanotube-modified glass fiber as described in claim 1, characterized in that, In step 2), the complexed colloidal solution further includes an ammonium citrate complexing agent; the concentration of the ammonium citrate complexing agent is 0.01~0.05 mol / L.

5. The method for preparing the composite sound-absorbing material based on carbon nanotube-modified glass fiber as described in claim 1, characterized in that, In step 3), the catalyst-carrying fiber passes through the first heating chamber and the second heating chamber at a linear velocity of 0.2~2m / min.

6. A composite sound-absorbing material based on carbon nanotube-modified glass fiber prepared by the preparation method according to any one of claims 1-5, characterized in that, The composite sound-absorbing material includes a glass fiber substrate, on the surface of which carbon nanotube micro / nano structures are grown in situ, and the top of the carbon nanotube micro / nano structures is loaded with silica microspheres; wherein the mass fraction of the carbon nanotube micro / nano structures is 10% to 60%.

7. The composite sound-absorbing material based on carbon nanotube-modified glass fiber as described in claim 6, characterized in that, The glass fiber substrate is selected from at least one of E-glass fiber, S-glass fiber, quartz fiber and high silica fiber, and its monofilament diameter is 5~25μm and its linear density is 100~9600tex.

8. The application of a mid-to-low frequency noise absorbing material in noise shielding, characterized in that, The mid-to-low frequency noise absorbing material is a composite sound-absorbing material made of carbon nanotube-modified glass fiber prepared by the preparation method described in claim 3.

9. The application of the low-to-medium frequency noise absorbing material as described in claim 8 in noise shielding, characterized in that, The noise shielding refers to building noise shielding, traffic noise shielding, or industrial noise shielding.

10. The application of the low-to-medium frequency noise absorbing material as described in claim 8 in noise shielding, characterized in that, The frequency of the medium and low frequency is 100~2000Hz.

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