Fiber-reinforced damping composite material and preparation method thereof

Abstract

The invention discloses a fiber reinforced composite material and a preparation method thereof, and solves the problem that the mechanical strength and damping performance of a traditional composite material are mutually restricted. The composite material is prepared by taking rubber with good vibration reduction and sound absorption effects as a matrix, containing a self-welding fiber skeleton structure to ensure the mechanical strength and adopting a step-by-step reconstruction strategy of'cage replacement ', has the advantages of light weight, high strength and strong designability, can replace sound absorption rubber to manufacture various integrated structural components, and has wide application prospects. The method has application prospects in the fields of vehicles, ships and the like.

Description

Technical Field

[0001] This invention belongs to the field of damping material technology, and relates to a fiber-reinforced damping composite material and its preparation method. Background Technology

[0002] In today's rapidly developing society, acoustic issues have attracted widespread attention. Vibration and noise not only affect the environment and human health, but also the operation of vehicles and the quality and function of machinery. Currently, traditional damping materials with practical value can be divided into damping alloy materials and polymer materials. Damping alloy materials mainly achieve damping performance by converting acoustic energy into heat energy through their internal microporous structure. Although they have high modulus, their loss factor is usually below 0.2, and their low damping performance cannot effectively suppress vibration and noise, making it difficult to meet the energy consumption and maneuverability requirements of vehicles. Polymer materials mainly dissipate acoustic energy through internal friction of molecular chain segments, but once the operating temperature exceeds the glass transition temperature of the polymer, the mechanical properties of the material drop sharply, with modulus generally below 10 MPa. They are prone to creep under high-frequency vibration or static loads and cannot be used alone as structural load-bearing components.

[0003] In fact, traditional damping materials face technical bottlenecks in balancing stiffness and energy dissipation under complex dynamic loads and environmental conditions. Single material systems struggle to achieve comprehensive performance indicators, and with the increasing demands for structural-functional integration, higher requirements are being placed on damping materials. For example, the automotive and marine industries require materials that combine high modulus, excellent damping performance, and lightweight characteristics. Especially for ships and submarines, which operate in waters ranging from 0 to 30°C year-round, underwater acoustic materials need to possess both excellent modulus and damping performance within this temperature range. Furthermore, anechoic tiles on submarines are noise reduction materials used underwater; they must meet impedance matching principles to ensure most sound waves are absorbed into the material while simultaneously avoiding detection by sonar above 1 kHz.

[0004] Existing composite material systems can combine the advantages of various materials to meet the requirements of underwater acoustic materials in multiple ways. Adding short fibers to rubber can increase the modulus, but the weak bonding force between the fiber and rubber interface leads to low stress transfer efficiency, making it prone to interfacial delamination in practical applications. Furthermore, the discontinuous fiber dispersion makes it difficult to form an effective support network. Alternating stacking of high-modulus layers and damping layers can achieve a synergistic effect of stiffness and damping, but the interlayer bonding process is complex, the requirements for adhesives are high, the lightweighting is insufficient, and it is prone to delamination failure under long-term humid and hot environments. The concept of "phonon glass" can utilize foam metal of different sizes to form various resonant units to achieve sound absorption across a wide frequency range, but the acoustic structure design is difficult. Therefore, existing composite materials rely on complex multilayer structure designs, making it difficult to achieve the synergistic optimization of high modulus (>200 MPa) and high damping (loss factor >0.3). Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a high-damping fiber-reinforced composite material that offers excellent vibration reduction and noise reduction, low specific gravity, high modulus, good dimensional stability, and ease of construction. This damping material effectively achieves a multi-component damping mechanism, compensating for the low modulus and poor dimensional stability of polymer damping materials while reducing the proportion of fibers, thereby improving the overall performance of the damping material.

[0006] Another object of the present invention is to provide a method for preparing the fiber-reinforced damping composite material.

[0007] Numerous studies have shown that simply layering high-modulus materials with damping materials, or pre-embedding high-modulus materials within damping materials, fails to achieve optimal reinforcement and construction results due to low integration. For example, patent application CN103707590 A discloses a sandwich damping composite material, where the core or face material is a high-modulus structural layer, with damping material positioned between the core or face material to provide overall mechanical and damping properties. However, the presence of a flat, rigid layer in this material's structural design makes it difficult to bond to structures with significant curvature. Patent application CN 109277571 A proposes an acoustic structure that addresses the deformation problem of acoustic materials under high loads through a pre-embedded metal skeleton and elastomer during the molding process, utilizing a composite effect. However, the increased overall rigidity of the material makes it difficult to bend, similarly hindering practical construction.

[0008] Fibers possess excellent mechanical properties, but simply adding fibers to a polymer matrix still results in a composite material's deformation temperature dependent on the polymer matrix. When the temperature exceeds the softening temperature of the polymer matrix, the dimensional stability of the material severely decreases due to the lack of strong inter-fiber interactions. To obtain stronger mechanical properties, a large amount of fiber needs to be added, leading to an increase in the material's specific gravity and hindering impedance matching. The manipulation of fibers to form a three-dimensional network structure is currently a key research focus. Patent CN 101407637 A proposes welding copper fibers in a copolymer together with tin during processing to form a copper-tin skeleton structure, thereby improving the copolymer's volume resistivity. Patent CN 112831186A proposes welding randomly dispersed glass fibers in silicone rubber with epoxy resin during processing to form a skeleton structure, improving the silicone rubber's compression resistance. However, these studies rely on welding agents to weld fibers during the blending process with the matrix, which requires specific thermodynamic and kinetic conditions, such as using a non-polar polymer as the matrix. Due to the weak intermolecular forces in this type of matrix, energy dissipation is mainly achieved through chain segment motion, resulting in poor damping performance. Common damping materials (such as nitrile rubber, neoprene rubber, polyurethane rubber, and acrylate rubber) contain polar groups (such as cyano groups, urethane groups, and ester groups). These groups enhance intermolecular forces and increase internal friction through interactions, thereby improving energy dissipation. Therefore, the focus of this invention is to achieve a synergistic optimization of high modulus, lightweight, and high damping by using damping materials as the matrix of a three-dimensional fiber skeleton structure.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a fiber-reinforced damping composite material, characterized in that it comprises a fiber skeleton and a damping matrix; the fiber skeleton is composed of chopped fibers and a welding agent, substantially forming a three-dimensional network skeleton structure composed of the welding agent and fibers; the welding agent is liquid at the processing temperature and solidifies into a high-strength solid; the damping matrix fills the pores of the fiber skeleton; the pore size of the fiber skeleton is 20~200 µm and the porosity is 45~95%.

[0010] The mass ratio of the fiber skeleton to the damping matrix is ​​(15~60): (85~40); preferably 40:60.

[0011] As a general inventive concept, this invention also provides a method for preparing the fiber-reinforced damping composite material, characterized by "replacing the old with the new," comprising the following steps: (1) The fiber, temporary matrix and welding agent are mixed and dispersed, and then shaped and processed to obtain a sheet material; (2) Remove the temporary matrix from the board (referred to as the "cage-removal" process) to obtain the fiber skeleton; (3) The damping matrix is ​​injected into the pores of the fiber skeleton (referred to as the "bird replacement" process) to obtain the fiber-reinforced damping composite material.

[0012] In step (1), the fibers are selected from glass fibers, carbon fibers, and various organic fibers, preferably glass fibers and carbon fibers. For inorganic fibers such as glass fibers with a large number of hydroxyl groups on their surface, surface treatment can be performed using a silane coupling agent. This silane coupling agent is selected from commonly used silane coupling agents such as γ-aminopropyltriethoxysilane (KH550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), and γ-methacryloyloxypropyltrimethoxysilane (KH570), with KH550 and KH560 being preferred. The glass fibers and carbon fibers are conventional in the art and can be selected from continuous fiber bundles or chopped fibers, with a preferred length of 0.1~20 mm and a preferred diameter of 1~50 μm. The temporary matrix before "cage stabilization" is a non-polar or low-polar polymer or polymer prepolymer with a melt viscosity of 0.1~100000 Pa·s, selected from silicone rubber, polystyrene, and various polyolefins. The welding flux is a polar polymer with a glass transition temperature greater than 30 °C, selected from epoxy resins and nylon resins. The epoxy resin is selected from bisphenol A type epoxy resin, polyphenolic glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, or glycidylamine epoxy resin, preferably liquid bisphenol A type epoxy resin and glycidylamine epoxy resin. The curing agent and accelerator suitable for the epoxy resin system are selected according to industry conventions. The curing agent mainly includes amines (aliphatic amines, alicyclic amines, aromatic amines, polyamides), acid anhydrides (aromatic acid anhydrides, alicyclic acid anhydrides, aliphatic acid anhydrides, acid anhydride adducts, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and their derivatives), and latent curing agents (modified aliphatic amines, aromatic diamines, dicyandiamide, imidazoles, organic acid anhydrides, organic hydrazides, Lewis acid-amine complexes, microcapsules and their derivatives); methylhexahydrophthalic anhydride is preferred. The accelerator can be selected from 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), 2-methylimidazole, etc.; DMP-30 is preferred. The epoxy resin is prepared by weighing each component according to the mass ratio of epoxy resin:curing agent:accelerator = 100: (50~100): (0~10), mixing them thoroughly with a stirrer, and allowing them to stand to obtain the required welding agent.

[0013] To achieve a certain strength, the fiber-reinforced rubber elastomer composite material of the present invention requires a suitable mass ratio of thermosetting welding agent and fiber content. Preferably, in step (1), the mass ratio of fiber, temporary matrix and welding agent is (10~40): (40~85): (5~30); more preferably, the mass ratio is 30: 80: 20.

[0014] Furthermore, the processing method in step (1) is selected from any one of the following methods: Melt blending: Conventional blending equipment such as open mills, internal mixers, or screw extruders are used to thoroughly mix and disperse the matrix, fibers, and welding agent. The resulting blend is then molded into the desired product using a compression molding process. The compression molding process can be designed as a single-step or multi-step operation to ensure the welding agent cures. The preferred compression molding time is 10-30 minutes. Masterbatch dispersion method: This method involves two steps. First, a portion of the matrix and fibers are blended using a mixing device such as an open mill, internal mixer, or extruder to prepare a masterbatch with a fiber content of 40-60 wt%. Then, this masterbatch, the remaining matrix, and the welding agent are uniformly dispersed again using the aforementioned mixing device. Finally, the uniformly mixed material is molded, with one or more molding steps to ensure the welding agent cures. The preferred molding time is 10-30 minutes.

[0015] The method for removing the matrix polymer in step (2) is a solvent dissolution method to avoid damaging the welding flux and fiber components and to improve the matrix removal efficiency, including: Solvent immersion method: Using a corrosion-resistant glass reactor or other vessel that can hold solvent, immerse the plate in the solvent at 10~50 ℃, and change the solvent regularly; Soxhlet extraction: Using a Soxhlet extraction apparatus, the substrate is subjected to Soxhlet extraction at a temperature above the boiling point of the solvent.

[0016] Subsequently, the treated sample was placed in a solvent for ultrasonic treatment and then removed and dried to obtain the fiber skeleton.

[0017] The solvent is selected from one or more solvents with solubility parameters close to that of the matrix, including: n-hexane, cyclohexane, petroleum ether, toluene, xylene, benzene, dichloromethane, chloroform, carbon tetrachloride, methanol, ethanol, isopropanol, acetone, butanone, cyclohexanone, ethyl acetate, butyl acetate, tetrahydrofuran, diethyl ether, N,N-dimethylformamide, acetonitrile, and dimethyl sulfoxide. To utilize the solubility difference between the matrix and the welding flux to achieve selective removal of the matrix, xylene and tetrahydrofuran are preferred.

[0018] Furthermore, the connection between the welding agent and the fiber in the fiber skeleton obtained in step (2) is any one or more of the following three methods: (1) the fiber surface is adhered to by the welding agent; (2) the end region of the fiber is covered with welding agent; (3) the node formed by the intersecting fibers is attached with welding agent.

[0019] Step (3) involves in-situ polymerization to inject the damping matrix into the pores of the fiber skeleton, including the following steps: (1) Inject the polymer solution into the fiber skeleton and exhaust the gas under a vacuum of -0.1 MPa to atmospheric pressure; (2) The temperature is increased until the polymerization reaction is complete, and the composite material is obtained by drying and polishing.

[0020] The polymer solution comprises at least one of the following components: acrylate monomers, epoxy resin monomers, polyurethane prepolymers, organosilicon monomers, or styrene monomers; preferably acrylate monomers. The acrylate monomers may be selected from methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), butyl methacrylate (BMA), isooctyl acrylate (2-EHA), hydroxyethyl acrylate (HEA), glycidyl acrylate (GA), ethyl acrylate urea (EAU), perfluorooctyl ethyl acrylate (FOEA), or derivatives thereof; preferably methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), or butyl methacrylate (BMA). The polymer solution comprises an initiator, the mass of which is 0.01-5% of the total mass of the polymer solution, and the initiator is selected from benzoyl peroxide (BPO), diaminodiphenyl sulfone (DDS), dibutyltin dilaurate (DBTDL), platinum catalyst, or dicumyl peroxide (DCP); preferably benzoyl peroxide (BPO). Fillers can be added to the solution to improve the overall performance of the composite material. These fillers can be selected from styrene-butadiene rubber powder, polyurethane microspheres, cork powder, montmorillonite, mica sheets, graphene nanosheets, and microporous calcium silicate; mica sheets and hollow glass microspheres are preferred. The filler accounts for 0%~50 wt% of the damping matrix by mass, preferably 1 wt%. The programmed temperature rise is achieved by oil bath or water bath heating at 90 ℃ for 30~180 minutes; or at 95 ℃ for 30~60 minutes. The drying conditions are: evaporation in a fume hood for 1~5 days to remove excess solvent, followed by drying in an oven at 30~300 ℃ for 24 hours.

[0021] Compared with the prior art, based on the above technical solution, the beneficial effects and advantages of the present invention are as follows: Traditional damping materials generally suffer from a technical bottleneck where mechanical properties and damping properties are mutually restrictive. Although using a three-dimensional fiber skeleton can effectively enhance the mechanical properties of composite materials, there is a significant performance incompatibility between the formation of the fiber skeleton and the addition of the damping matrix when preparing damping composite materials using this method. This application innovatively adopts a step-by-step process of "replacing the cage with the bird" to avoid this contradiction. After molding a blend of temporary matrix, chopped fibers, and welding agent, the temporary matrix is ​​extracted to achieve "cage removal," resulting in a fiber skeleton as the reinforcing material. Then, the damping matrix and fiber skeleton are combined through in-situ polymerization to achieve "bird replacement," obtaining a fiber-reinforced damping composite material.

[0022] Compared with traditional fiber-reinforced damping composites, this fiber-reinforced damping composite has the following advantages: (1) While significantly reducing the fiber content, it effectively improves the problems of insufficient modulus and poor dimensional stability of damping rubber; (2) The fiber skeleton structure can not only control the pore parameters (including porosity, pore size and micropore morphology) through processing technology, but also breaks through the constraint that the deformation temperature of traditional damping materials is limited by the softening point; (3) Based on the excellent damping and bonding properties of acrylate rubber as the damping matrix, the designability of the effective damping temperature range of the composite material under the premise of achieving high modulus is greatly improved through copolymerization reaction and filler control; (4) Utilizing the plasticity of the fiber skeleton, complex curved surface components can be prepared by the process of replacing the cage with a new one after coating and curing, which can realize the construction of large curvature surfaces such as vehicles and ships. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the method for preparing the fiber-reinforced damping composite material according to the present invention.

[0024] Figure 2 This is a schematic diagram of an optical microscope image of the glass fiber-nylon 6 skeleton structure described in this invention (the temporary matrix in the plate has been removed and the damping matrix has been injected into the pores of the fiber skeleton).

[0025] Figure 3 The curves show the change of energy storage modulus with temperature for Embodiment 2 and Comparative Examples 1 and 2 of the present invention.

[0026] Figure 4 The curves show the loss factor as a function of temperature for Embodiment 2 and Comparative Examples 1 and 2 of the present invention. Detailed Implementation

[0027] The present invention will be further illustrated below through embodiments, the purpose of which is solely to provide a better understanding of the invention. Therefore, the examples given in this invention do not limit the scope of protection of the invention.

[0028] Unless otherwise specified, experimental methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. Room temperature refers to the operating room temperature, which is 10–30 °C.

[0029] This invention provides a fiber-reinforced damping composite material, characterized in that it comprises a fiber skeleton and a damping matrix; the fiber skeleton is composed of chopped fibers and a welding agent, essentially forming a three-dimensional network skeleton structure composed of the welding agent and fibers; the welding agent is liquid at the processing temperature and solidifies into a high-strength solid; the damping matrix fills the pores of the fiber skeleton; the pore size of the fiber skeleton is 20~200 µm, and the porosity is 45~95%. The mass ratio of the fiber skeleton to the damping matrix is ​​(15~60):(85~40); preferably 40:60.

[0030] As a general inventive concept, this invention also provides a method for preparing the fiber-reinforced damping composite material, characterized by "replacing the old with the new," comprising the following steps: (1) The fiber, temporary matrix and welding agent are mixed and dispersed, and then shaped and processed to obtain a sheet material; (2) The fiber skeleton is obtained through the "cage-raising" process; (3) The fiber-reinforced damping composite material is obtained by adopting the "bird replacement" process.

[0031] The equipment used in the preparation method of the present invention is conventional in the art. In step (1), the affinity between the fiber and the welding agent can be changed by adjusting the viscosity of the temporary matrix, the viscosity ratio of the welding agent to the temporary matrix, and the fiber surface modification. Fillers can also be added to effectively improve the interfacial interaction between the welding agent and the fiber. In the molding process, the performance of the sheet material can be enhanced by controlling the temperature, time, shear rate, roller or rotor spacing, and rotor shape during the dispersion and mixing process. In step (2), the etching morphology of the fiber skeleton can be improved by solvent selection, temperature control, and time control. In step (3), the final performance of the fiber-reinforced damping composite material can be controlled by solvent selection, initiator selection, temperature program setting, temperature medium selection, and filler addition. There are many types of chopped fibers, temporary matrix, welding agent, solvent, initiator, and fillers, which can be selected according to relevant professional books and papers. Unless otherwise specified, the raw materials and reagents in the present invention are all commercially available.

[0032] Example 1 First, polystyrene (melt index of 8 g / 10 min as determined by GB / T 3682.1), antioxidant Irganox 1076 FD (0.3% of polystyrene by mass), and glass fiber (KH550 modified) were placed in a 240 ℃ internal mixer and mixed for 3 minutes. Then, nylon 6 (melt index of 102.1 g / 10 min as determined by GB / T 3682.1) was added, and the mixture was further mixed for 7 minutes before being discharged. The mass ratio of polystyrene (PS), nylon 6 (PA6), and glass fiber (GF) was 80:20:30. The mixture was then molded at 240 ℃ and 10 MPa for 10 minutes to obtain a sheet. Xylene was used as a solvent, and polystyrene was removed from the sheet by Soxhlet extraction. The heating temperature was set above the solvent boiling point, the Soxhlet extraction time was 72 hours, and the siphon circulation was 8 times / hour. After soaking, the sample was removed, ultrasonicated for 1 hour, rinsed, and dried at 80 °C for 24 hours to obtain a glass fiber-nylon 6 skeleton structure. The porosity of the fiber skeleton was 76%, and the average pore size of the cross-section was 102 µm. A damping matrix was used to fill the fiber skeleton at a mass ratio of 40:60. The damping matrix was prepared by copolymerization of acrylate solution, using a blend of butyl acrylate (BA) and butyl methacrylate (BMA) at a mass ratio of 60:40. Benzoyl peroxide (BPO) (0.2% of the total polymer solution mass) was added to the solution and stirred to dissolve, resulting in a mixed solution. The fiber skeleton was placed in a container with the mixed solution, and degassing was performed under a vacuum of -0.1 MPa for 30 minutes. The copolymerization method involved incubating the container in a 90 °C water bath for 180 minutes, followed by a 95 °C water bath for 60 minutes. The sample was then removed and placed in a fume hood for 3 days to remove excess solvent. After drying in an 80 °C oven for 24 hours, the sample was polished to obtain the fiber-reinforced damping composite material. The resulting sample had a storage modulus of 233 MPa and a maximum loss factor of tan δ. max = 0.31, effective damping temperature range 15.6 ℃, glass transition temperature 8.0 ℃. Sample composition and specific results are shown in Tables 1 and 3. Figure 1 This is a schematic diagram of the sample preparation process. Figure 2 This is a schematic diagram of an optical microscope image of the sample.

[0033] Example 2 The acrylate solution was a mixture of butyl acrylate (BA) and butyl methacrylate (BMA) in a mass ratio of 70:30, otherwise the same as in Example 1. The resulting sample had a storage modulus of 252 MPa and a maximum loss factor of tan δ. max = 0.36, effective damping temperature range 19.4 ℃, glass transition temperature -6.6 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0034] Example 3 The acrylate solution used was a mixture of butyl acrylate (BA) and butyl methacrylate (BMA) in a mass ratio of 80:20, otherwise the same as in Example 1. The storage modulus of the obtained sample was 233 MPa, and the maximum loss factor tan δ was... max = 0.34, effective damping temperature range 15.1 ℃, glass transition temperature -13.2 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0035] Example 4 Mica (1% by mass of the total polymer solution) was added to the solution, otherwise the same as in Example 2. The resulting sample had a storage modulus of 309 MPa and a maximum loss factor of tan δ. max = 0.41, effective damping temperature range 38 ℃, glass transition temperature -7.0 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0036] Example 5 Hollow glass microspheres (1% of the total mass of the polymer solution) were added to the solution, otherwise the same as in Example 1. The resulting sample had a storage modulus of 285 MPa and a maximum loss factor of tan δ. max = 0.36, effective damping temperature range 22.9 ℃, glass transition temperature 8.5 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0037] Example 6 The acrylate solution used was a mixture of butyl acrylate (BA) and ethyl acrylate (EA) in a mass ratio of 30:70, otherwise the same as in Example 1. The storage modulus of the obtained sample was 277 MPa, and the maximum loss factor tan δ was... max = 0.44, effective damping temperature range 26.7 ℃, glass transition temperature 1.5 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0038] Example 7 In Example 6, the fiber was replaced with T300 carbon fiber (CF) instead of GF. The porosity of the fiber skeleton was 72.0%, and the average pore size of the cross-section was 65 µm. The resulting sample had a storage modulus of 412 MPa and a maximum loss factor of tan δ. max = 0.41, effective damping temperature range 27.5 ℃, glass transition temperature -1.4 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0039] Example 8 Silicone rubber (viscosity 1000 Pa·s at room temperature) and T300 carbon fiber were placed in a mixer and mixed for 3 minutes at room temperature. Epoxy resin was then added, and mixing continued for another 7 minutes before sample extraction. The mass ratio of silicone rubber (SR), epoxy resin (EP), and carbon fiber (CF) was 80:20:30. EP consisted of TDE-85 resin, curing agent methylhexahydrophthalic anhydride, and accelerator 2,4,6-tris(dimethylaminomethyl)phenol, with a mass ratio of 100:85:5. The mixture was thoroughly mixed using a paddle mixer and allowed to stand. The mixture was then molded at 100 °C and 10 MPa for 30 minutes, followed by further molding at 150 °C and 10 MPa for 30 minutes to obtain the sheet material. Tetrahydrofuran was used as the solvent, and Soxhlet extraction was employed to remove the silicone rubber from the sheet material. The heating temperature was set above the solvent boiling point, and the Soxhlet extraction time was 72 hours; the siphon circulation was performed 8 times per hour. After soaking, the sample was removed, ultrasonicated for 1 hour, rinsed, and dried at 80 °C for 24 hours to obtain a carbon fiber-epoxy resin skeleton structure. The porosity of the fiber skeleton was 81.3%, and the average pore size of the cross-section was 50 µm. A damping matrix was used to fill the fiber skeleton, with a mass ratio of fiber skeleton to damping matrix of 40:60. The damping matrix was prepared by copolymerization of acrylate solution, using a blend of butyl acrylate (BA) and ethyl acrylate (EA) at a mass ratio of 60:40. Benzoyl peroxide (BPO) (0.2% by mass of the solution) was added to the solution and stirred to dissolve, resulting in a mixed solution. The fiber skeleton was placed in a container with the mixed solution, and degassing was performed under a vacuum of -0.1 MPa for 30 minutes. The copolymerization method involved incubating the container in a 90 °C water bath for 180 minutes and then in a 95 °C water bath for 60 minutes. The sample was then removed and placed in a fume hood for 3 days to evaporate excess solvent. After drying in an 80 °C oven for 24 hours, the sample was polished to obtain the fiber-reinforced damping composite material. The resulting sample had a storage modulus of 745 MPa and a maximum loss factor of tan δ. max = 0.32, effective damping temperature range 32.1 ℃, glass transition temperature 1.6 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0040] Example 9 The acrylate solution used was a blend of butyl acrylate (BA) and methyl acrylate (MA) in a mass ratio of 60:40, with other parameters the same as in Example 2. The resulting sample had a storage modulus of 252 MPa and a maximum loss factor of tan δ. max = 0.48, effective damping temperature range 28.5 ℃, glass transition temperature -3.5 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0041] Example 10 In Example 9, the fiber was replaced with T300 carbon fiber (CF) instead of GF. The porosity of the fiber skeleton was 72.0%, and the average pore size of the cross-section was 65 µm. The resulting sample had a storage modulus of 376 MPa and a maximum loss factor of tan δ. max = 0.49, effective damping temperature range 23.5 ℃, glass transition temperature 6.3 ℃. Sample composition and specific results are shown in Tables 1 and 3.

[0042] Comparative Example 1 First, polystyrene (melt index determined by GB / T 3682.1: 8 g / 10 min), antioxidant Irganox 1076 FD (0.3% by mass of polystyrene), and T300 carbon fiber were placed in a 240 ℃ internal mixer and mixed for 3 minutes. Then, nylon 6 (melt index determined by GB / T 3682.1: 102.1 g / 10 min) was added, and the mixture was further mixed for 7 minutes before being discharged. The mass ratio of polystyrene (PS), nylon 6 (PA6), and carbon fiber (CF) was 80:20:30. The mixture was then molded at 240 ℃ and 10 MPa for 10 minutes to obtain a sheet. The storage modulus of the obtained sample was 5473 MPa, and the maximum loss factor tanδ was [missing value]. max = 0.52, effective damping temperature range 15.0 ℃, glass transition temperature 125.0 ℃. Sample composition and specific results are shown in Tables 2 and 4.

[0043] Comparative Example 2 In Comparative Example 1, the matrix was replaced with polypropylene (PP) instead of PS. The resulting sample had a storage modulus of 2895 MPa and a maximum loss factor of tan δ. max = 0.04, no effective damping temperature range, glass transition temperature 100.0 ℃. Sample composition and specific results are shown in Tables 2 and 4.

[0044] Comparative Example 3 In Comparative Example 1, the matrix was replaced with polybutyl acrylate (PBA), the welding agent was replaced with epoxy resin (EP) instead of PA6, and the fiber was replaced with glass fiber (GF) instead of CF. EP consisted of TDE-85 resin, curing agent methylhexahydrophthalic anhydride, and accelerator 2,4,6-tris(dimethylaminomethyl)phenol in a mass ratio of 100:85:5. The mixture was thoroughly mixed using a paddle stirrer and then allowed to stand. The resulting sample had a storage modulus of 45 MPa and a maximum loss factor tan δ. max = 1.70, effective damping temperature range 40.0 ℃, glass transition temperature 5.8 ℃. Sample composition and specific results are shown in Tables 2 and 4.

[0045] Table 1. Sample composition of the examples Serial Number Fiber skeleton to mass ratio Damping matrix to mass ratio Damping matrix addition method Mass ratio of fiber skeleton to damping matrix <![CDATA[Filler and its mass ratio a > Example 1 GF:PA6=60:40 PBA: PBMA = 60: 40 In-situ co-aggregation 40: 60 none Example 2 GF:PA6=60:40 PBA: PBMA = 70: 30 In-situ co-aggregation 40: 60 none Example 3 GF:PA6=60:40 PBA: PBMA = 70: 30 In-situ co-aggregation 40: 60 none Example 4 GF:PA6=60:40 PBA: PBMA = 70: 30 In-situ co-aggregation 40: 60 1% Mica Example 5 GF:PA6=60:40 PBA: PBMA = 70: 30 In-situ co-aggregation 40: 60 1% Hollow Glass Microspheres Example 6 GF:PA6=60:40 PBA: PEA = 30: 70 In-situ co-aggregation 40: 60 none Example 7 CF: PA6 = 60: 40 PBA: PEA = 30: 70 In-situ co-aggregation 40: 60 none Example 8 CF:EP=60:40 PBA: PEA = 30: 70 In-situ co-aggregation 40: 60 none Example 9 GF:PA6=60:40 PBA: PMA = 60: 40 In-situ co-aggregation 40: 60 none Example 10 CF: PA6 = 60: 40 PBA: PMA = 60: 40 In-situ co-aggregation 40: 60 none a The mass ratio of the filler shown is the mass ratio of the filler to the damping matrix.

[0046] Table 2. Composition of Comparative Samples Serial Number Fiber skeleton to mass ratio Damping matrix to mass ratio Damping matrix addition method Mass ratio of fiber skeleton to damping matrix <![CDATA[Filler and its mass ratio a <!-- 7 -->]]> Comparative Example 1 CF: PA6 = 60: 40 PS direct blending 40: 60 none Comparative Example 2 CF: PA6 = 60: 40 PP direct blending 40: 60 none Comparative Example 3 GF:EP=60:40 PBA direct blending 40: 60 none a The mass ratio of the filler shown is the mass ratio of the filler to the damping matrix.

[0047] Table 3 Performance of Samples from Examples Serial Number <![CDATA[Storage modulus a (MPa)]]> <![CDATA[Maximum loss factor tan δ max > <![CDATA[Effective damping temperature range b (°C)]]> <![CDATA[Glass transition temperature c (°C)]]> Example 1 233 0.31 15.6 8.0 Example 2 252 0.36 19.4 -6.6 Example 3 233 0.34 15.1 -13.2 Example 4 360 0.41 38.0 -7.0 Example 5 285 0.36 22.9 8.5 Example 6 277 0.44 26.7 1.5 Example 7 412 0.41 27.5 -1.4 Example 8 745 0.32 32.1 1.6 Example 9 252 0.48 28.5 3.5 Example 10 376 0.49 23.5 6.3 a The energy storage modulus shown was measured by DMA under test conditions of 25 °C, 10 Hz, and 0.05% strain.

[0048] b The effective damping temperature range shown is the temperature range where the loss factor tan δ ≥ 0.3.

[0049] c The glass transition temperature shown was measured by DMA under test conditions of 10 Hz and 0.05% strain.

[0050] Table 4 Performance of Comparative Samples Serial Number <![CDATA[Storage modulus a (MPa)]]> <![CDATA[Maximum loss factor tan δ max > <![CDATA[Effective damping temperature range b (°C)]]> <![CDATA[Glass transition temperature c (°C)]]> Comparative Example 1 5473 0.52 15.0 125.0 Comparative Example 2 2895 0.08 none 100.0 Comparative Example 3 45 1.70 40.0 5.8 a The energy storage modulus shown was measured by DMA under test conditions of 25 °C, 10 Hz, and 0.05% strain.

[0051] b The effective damping temperature range shown is the temperature range where the loss factor tan δ ≥ 0.3.

[0052] c The glass transition temperature shown was measured by DMA under test conditions of 10 Hz and 0.05% strain.

[0053] The results in Tables 1 and 3 demonstrate that the introduction of the fiber skeleton structure in this invention can significantly improve the overall performance of the material. For example, based on the composition and properties of the samples in Examples 1-3, damping materials with different effective damping frequency ranges can be obtained by adjusting the glass fiber-nylon 6 skeleton structure and the acrylate solution. Figure 3 and Figure 4As shown, Example 2 exhibits a storage modulus exceeding 200 MPa and a relatively wide effective damping temperature range, achieving synergistic optimization of high modulus, lightweight, and high damping. Based on the sample composition and properties of Examples 4-5, adding fillers during the acrylate copolymerization process widens the effective damping temperature range and shifts the effective damping frequency range. Based on the sample composition and properties of Examples 6-10, changing the types of fibers and welding agents can improve the sample's storage modulus. For example, replacing the glass fiber-nylon 6 skeleton structure with a carbon fiber-epoxy resin structure increases the sample's storage modulus by approximately 500 MPa.

[0054] The results in Tables 2 and 4 illustrate the necessity and rationality of the "replacing the old with the new" fiber-reinforced damping composite material preparation method, which is the key feature of this invention. Directly using a non-polar polymer as the damping matrix presents two problems. First, based on the composition and properties of Comparative Example 1, directly using the relatively weakly polar polystyrene (PS), although the sample has a storage modulus as high as 5473 MPa, its glass transition temperature is outside the applicable temperature range, resulting in a maximum loss factor temperature of 125.0 ℃ for the fiber-reinforced damping composite material, which is difficult to meet the needs of practical applications. Second, based on the composition and properties of Comparative Example 2, directly using non-polar but somewhat crystalline polypropylene (PP) as the damping matrix results in a loss factor of only 0.10 due to restricted molecular motion, leading to a maximum loss factor of only 0.08 for the fiber-reinforced damping composite material, which is also difficult to meet the needs of practical applications. If a polar polymer is used as the damping matrix, based on the composition and performance of Comparative Example 3, although the effective damping temperature range is wide and the average loss factor is large, the average storage modulus of the fiber-reinforced damping composite material is as low as 45 MPa, indicating that the fiber skeleton structure has not been formed. Figure 3 and Figure 4 As shown, by combining the energy storage modulus and loss factor of the comparative examples and the comparative examples, it is found that using a non-polar polymer as the matrix before "cage replacement" and using a polar damping matrix to "replace the bird" is necessary to prepare a fiber skeleton reinforced composite material with high modulus and high damping at the application temperature.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A fiber-reinforced damping composite material, characterized in that, It includes a fiber skeleton and a damping matrix; the fiber skeleton is composed of chopped fibers and a welding agent, which essentially forms a three-dimensional network skeleton structure composed of welding agent and fibers; the welding agent is liquid at the processing temperature and becomes a high-strength solid after solidification; the damping matrix fills the pores of the fiber skeleton; the pore size of the fiber skeleton is 20~200 µm and the porosity is 45~95%.

2. The fiber-reinforced damping composite material according to claim 1, characterized in that, The mass ratio of the fiber skeleton to the damping matrix is ​​(15~60): (85~40).

3. A method for preparing the fiber-reinforced damping composite material as described in claim 1 or 2, characterized in that, Includes the following steps: (1) The fiber, temporary matrix and welding agent are mixed and dispersed, and then shaped and processed to obtain a sheet material; (2) Remove the temporary matrix from the board obtained in step (1) to obtain the fiber skeleton; (3) The damping matrix is ​​injected into the pores of the fiber skeleton obtained in step (2) to obtain the fiber-reinforced damping composite material.

4. The preparation method according to claim 3, characterized in that, In step (1), the fiber is selected from glass fiber, carbon fiber or organic fiber; the temporary matrix is ​​a non-polar or low-polar polymer or polymer prepolymer with a melt viscosity of 0.1~100000 Pa·s; the welding flux is a polar polymer with a glass transition temperature greater than 30 ℃. The non-polar or low-polar polymer is selected from silicone rubber, polystyrene, or polyolefin; the polar polymer is selected from epoxy resin or nylon resin.

5. The preparation method according to claim 3, characterized in that, In step (1), the mass ratio of fiber, matrix and welding flux is (10~40): (40~85): (5~30).

6. The preparation method according to claim 3, characterized in that, The processing method in step (1) is selected from any one of the following methods: Melt blending method: Using conventional blending equipment such as open mill, internal mixer or screw extruder, the matrix, fiber and welding agent are fully mixed and dispersed. The resulting blend is then molded into the desired product through compression molding. The compression molding process can be designed as a single step or multi-step operation to ensure the curing of the welding agent. Masterbatch dispersion method: This method is carried out in two steps. First, a portion of the matrix and fiber are blended using a mixing device such as an open mill, internal mixer or extruder to prepare a masterbatch with a fiber content of 40~60 wt%. Then, this masterbatch, the remaining matrix and welding agent are uniformly dispersed again using the aforementioned mixing device. Finally, the uniformly mixed material is molded. The molding steps are one or more steps to ensure the curing of the welding agent.

7. The preparation method according to claim 3, characterized in that, The method for removing the matrix polymer in step (2) is a solvent dissolution method, including: Solvent immersion method: Immerse the board in solvent at 10~50 ℃, and change the solvent regularly; Soxhlet extraction: Soxhlet extraction of the sheet material is performed at a temperature above the boiling point of the solvent. Subsequently, the treated sample was placed in a solvent for ultrasonic treatment and then removed and dried to obtain the fiber skeleton.

8. The preparation method according to claim 3, characterized in that, The connection between the welding agent and the fiber in the fiber skeleton obtained in step (2) is any one or more of the following three methods: (1) the fiber surface is adhered to by the welding agent; (2) the end area of ​​the fiber is covered with welding agent; (3) the node formed by the intersecting fibers is attached with welding agent.

9. The preparation method according to claim 3, characterized in that, Step (3) involves in-situ polymerization to inject the damping matrix into the pores of the fiber skeleton, including the following steps: (1) Inject the polymer solution into the fiber skeleton and exhaust the gas under a vacuum of -0.1 MPa to atmospheric pressure; (2) The temperature is increased until the polymerization reaction is complete, and the composite material is obtained by drying and polishing.

10. The method according to claim 9, characterized in that, The polymer solution in step (1) contains at least one of the following components: acrylate monomers, epoxy resin monomers, polyurethane prepolymers, organosilicon monomers, or styrene monomers; the acrylate monomers are selected from methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), butyl methacrylate (BMA), isooctyl acrylate (2-EHA), hydroxyethyl acrylate (HEA), glycidyl acrylate (GA), ethyl acrylate urea (EAU), perfluorooctyl ethyl acrylate (FOEA), or derivatives thereof; the polymer solution contains an initiator, the mass of which is 0.01~5% of the total mass of the polymer solution, the initiator being selected from benzoyl peroxide (BPO), diaminodiphenyl sulfone (DDS), dibutyltin dilaurate (DBTDL), platinum catalyst, or dicumyl peroxide (DCP).

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