Preparation method of a multi-scale interface toughened resin matrix composite material structure

Abstract

The present invention discloses a preparation method for a multi-scale interface toughened resin matrix composite material structure. The structure is a "sandwich" sandwich structure, with a fiber reinforcement as the "core" and a toughening layer as the "skin", and a fiber reinforced composite material is prepared through the VARTM preparation process. The innovation of the present invention lies in that through the toughening treatment of the interface between the fiber and the resin and the interlayer between the fibers, the toughening effect is localized at the "surface layer" position that contributes the most to the toughness of the composite material, so as to obtain the toughening effect to the greatest extent. The present invention conducts a toughening treatment on the toughening layer of the composite material panel through means such as pretreatment of the toughening layer, addition of one-dimensional nanoparticles, two-dimensional nanosheets, three-dimensional organic frameworks, etc. The toughening layer has good wettability and good bonding force with the resin, and the mechanical properties of the prepared composite material are significantly improved. The flexural strength is increased by 86.5%, the impact strength is increased by 63.2%, and the interlaminar shear strength is increased by 78.8%. The preparation process of the present invention is simple, has a short process, high efficiency and is green and environmentally friendly, can be industrialized, and has good development prospects.

Description

Technical Field

[0001] The present invention relates to the field of preparation of toughened resin matrix composites, and particularly relates to a method for preparing a multi-scale interface toughened resin matrix composite structure. Background Art

[0002] Resin matrix composites are widely used in the fields of automobiles, rail transit, and aerospace due to their good thermal stability, corrosion resistance, and relatively good mechanical properties. Their output and application level can also reflect the development degree of a country's industrial technology from the side. However, the crosslinking density of the resin matrix is large, and after reacting with the curing agent, its rigidity becomes large, and there is a problem of high brittleness. At the same time, when the sandwich structure composite material is impacted during use, it is easy to cause microcracks and delamination. The further expansion of the cracks and delamination leads to the failure of the composite material structure, thus restricting its application fields. In order to improve the impact resistance of resin matrix composites, it is generally achieved by improving the toughness of the composites. As a lightweight, high-rigidity, and high-strength structural material, fiber-reinforced resin matrix composites have been widely used in advanced engineering fields. There are mainly two ways for fiber-reinforced resin matrix composites: one is to toughen the epoxy resin matrix, and the other is to toughen the interlayer of the composite material. Interlayer toughening is to insert a thin toughening material layer between the composite material matrices to improve the fracture toughness and impact resistance of the composite material. The traditional in-situ toughening technology will greatly increase the viscosity of the resin matrix, while interlayer toughening can maximize the protection of the mechanical properties of the resin matrix. Interlayer "off-site" toughening is to separate the main components of the resin matrix from the toughening components, and localize the toughening effect at the interlayer position that contributes the most to the toughness of the composite material, so as to obtain the toughening effect to the greatest extent. However, there are problems such as poor bonding force between the toughening layer and the resin matrix and incomplete penetration of the resin into the toughening layer in fiber interlayer toughening. Low-speed impact will cause fractures in the resin-rich areas between layers, forming delamination damage, which will greatly reduce the mechanical properties of the composite material. In the process of using the sandwich structure composite material, surface / core structure debonding failure is likely to occur. Surface / core debonding will greatly affect the performance of the composite material structure, thus leading to structural damage or failure. During the stress process, the skin panel of the sandwich structure composite material mainly bears bending, torsion, and various internal loadings, and the middle core material is mainly responsible for transmitting plane shear and compression loads. The strain of the panel is relatively large, and the strain of the core material is relatively small. Therefore, the toughening of the sandwich structure is mainly the toughening of its interface.

[0003] CN 103554478 B discloses a phosphorus-containing polyaryletherketone for toughening bis-maleimide resin matrix composites interlayer and its toughening film. Aiming at the specific process requirements of preparing composite laminates with bis-maleimide resin system for RTM molding process, a phosphorus-containing polyaryletherketone film for interlayer toughening matching with the RTM molding process of bis-maleimide resin is designed. It can maintain a complete film structure, effectively avoid the sudden increase in resin viscosity caused by the dissolution of the film during the injection process, and cause problems such as difficult resin flow. This film greatly improves the interlayer toughness of the composite material, and the impact compression strength is increased from 160 MPa to 255 MPa. At the same time, the phosphorus-containing polyaryletherketone has excellent heat resistance.

[0004] CN 107141717 A reports a preparation method of a transparent self-toughening dicyandiamide / epoxy resin-based composite material. Aiming at the problems of large heat release, concentrated heat, phase separation of resin and curing agent, and large brittleness and opacity of the cured product in the dicyandiamide-cured epoxy system, a liquid epoxy resin, a solid epoxy resin, a dicyandiamide curing agent and a promoter are used to prepare an epoxy resin by solution reaction. The peak heat flow of this system is reduced by more than 48% compared with the usual dicyandiamide / epoxy resin system, the heat release is reduced by more than 38%, and at the same time, the elongation at break of the resin reaches more than 3.5%, the tensile strength reaches 80 MPa, and the impact strength reaches 24 KJ / m 2 Above.

[0005] CN 112208161 A invented a laminated fiber body toughened resin matrix composite material and its preparation method. By etching and hydroxylation treatment of the surface of aluminosilicate fiber cloth to obtain fiber preform A, and successively using silica sol solution filling treatment and carbon nanotube surface modification of alumina fiber cloth to obtain preform C, a polyamide resin solution is coated on the surfaces of fiber preform A and fiber preform C, stacked and pressed into shape to obtain a laminated fiber body toughened resin matrix composite material. The preparation method of the invention effectively improves the microscopic structure of the fiber interface and the mechanical bonding effect between fibers in different directions, and shows excellent mechanical properties macroscopically. The flexural strength is increased by 202.8% compared with the control group. Summary of the Invention

[0006] The interfacial bonding ability between fiber and resin is the main influencing factor affecting the toughening effect. The purpose of the present invention is to overcome the deficiencies of the prior art. The structural design and preparation method of a multi-scale interfacial toughened resin matrix composite material mainly includes: toughening layer pretreatment, adding one-dimensional nano-toughening particles, two-dimensional nano-sheets, three-dimensional organic frameworks and material self-toughening at five different scales. Interfacial toughening localizes the toughening effect at the surface layer position that contributes the most to the toughness of the composite material, so as to obtain the toughening effect to the greatest extent. The quality of the interfacial toughening effect will directly affect the performance of the composite material structure.

[0007] The present invention designs a sandwich multi-interlayer structure, with a fiber reinforcement as the "core" and a toughened fiber layer as the "skin", and prepares a composite material through the VARTM molding process. The structure shown from top to bottom is: fiber toughening layer - core material - fiber toughening layer.

[0008] Starting from improving the toughness of the face-core interface of the sandwich structure and delaying the premature failure of the sandwich material caused by delamination, the present invention solves the problem that the toughening layer of glass fiber mat as a carbon fiber resin matrix composite material will delaminate and fall off during the stress process. On the premise of maintaining the original stability of the composite material, the mechanical properties of the composite material are greatly improved.

[0009] The object of the present invention is mainly achieved through the following technical solutions: A multi-scale interface toughened resin matrix composite material structure design and its preparation method, characterized by including: mineral fibers such as glass fiber, carbon fiber, aluminum silicate fiber or synthetic fibers such as aramid fiber, polyethylene fiber; nanoparticles such as nylon, silicon dioxide and titanium dioxide; two-dimensional nanomaterials such as hydroxylated multi-walled carbon nanotubes (MWCNT-COOH), hexagonal boron nitride, MXene; three-dimensional nanomaterials such as metal-organic frameworks; thermosetting resin or thermoplastic resin; curing agent; adhesive and antistatic agent. The multi-dimensional nano-fillers can increase the surface roughness of the fibers, and the existing carboxyl groups can bond with the groups in the fibers and the resin. At the same time, the ionized H + can act as a curing agent and participate in the curing process of the resin, reducing the cross-linking degree of the resin, making the resin easier to penetrate, increasing the interfacial bonding force between the resin and the toughening layer, and thus improving the overall mechanical properties of the composite material. The unique three-dimensional skeleton structure of the metal-organic framework can be used as a carrier to evenly distribute the nano-fillers in the fiber toughening layer, reducing the problems of structural instability and mechanical failure caused by aggregation.

[0010] The specific steps are as follows:

[0011] Step 1: 1. Determine the ratio of fiber to resin content to achieve the best fiber reinforcement effect; 2. Through formula design, adjust the ratio of the fiber toughening layer to the nano-fillers and the modification scheme; 3. Determine the ratio of the "core" to the "skin" of the sandwich structure; 4. Determine the composite material structure design and its molding process.

[0012] The present invention provides a structural design and a preparation method of a multi-scale interface toughened resin matrix composite material, and its formula is as follows: 1. Fibers and resin each account for 50% of the overall composite material, 50-200 parts of fibers, and 50-200 parts of resin; 2. 5-20 parts of one-dimensional nanoparticles; 3. 5-35 parts of two-dimensional nanosheets; 4. 2-20 parts of three-dimensional nano-framework; 5. 20-100 parts of functional resin; 6. 5-30 parts of adhesive; 7. 5-20 parts of antistatic agent; Further, the functional resin preferably has one or more of high-strength and high-toughness resin, organosilicon-modified waterborne polyurethane resin, phenolic resin, or black polysulfone resin;

[0013] Step 2: Preparation of the fiber felt toughening layer (skin): In this study, the papermaking process is adopted to fully mix mineral fibers or synthetic fibers, multi-dimensional nano-fillers, and functional resins. With fibers as the scaffold and nano-fillers as the filling, a fiber toughening material with a stable structure is constructed.

[0014] Further, surface pretreatment of the fibers: First, weigh 50-100 parts of mineral fibers or synthetic fibers. (1) Mineral fibers: Place the mineral fibers in a muffle furnace and heat them to 300-700 °C at a rate of 5 °C - 30 °C / min, hold for 30-90 min to remove some surface impurities. The calcined mineral fibers are dispersed in acetone or butanone and subjected to ultrasonic surface cleaning for 2-4 h, washed three times with ethanol and deionized water or distilled water respectively to remove acetone or butanone, and then transferred to an oven at 40-80 °C for drying and collection.

[0015] Further, (2) Synthetic fibers: The pretreatment of synthetic fibers includes desizing and scouring, relaxation processing, pre-shaping, and alkali weight reduction treatment. Immerse the synthetic fibers in a solution of polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, sodium silicate, and non-ionic surfactant for 10-50 min to remove the sizing on the fiber surface, then place them in water at 30-60 °C for washing, and finally wash them repeatedly three times with deionized water or distilled water to complete the desizing and scouring pretreatment. The desized and scoured synthetic fibers are subjected to relaxation processing and pre-shaping under the action of heat and humidity, additives, and mechanical kneading to eliminate the internal stress generated during the desizing and scouring process and improve the strength and toughness of the fibers themselves. Generally, polyester synthetic fibers also require alkali weight reduction treatment, that is, the fibers are immersed in a high-temperature and relatively concentrated caustic soda solution to achieve the best performance of the fibers.

[0016] Furthermore, weigh the pretreated mineral fibers or synthetic fibers, put them into a 1000 ml fiber disintegrator, add 5-30 parts of adhesive and 5-20 parts of antistatic agent, and stir for 3-10 min to obtain preform A;

[0017] Further, 5 - 20 parts of nanoparticles such as Cu, Ni, and Zr are configured into a solution, and the preform A is immersed in this solution. After 30 - 60 minutes, the preform B is obtained.

[0018] Further, 5 - 35 parts of nanosheets such as polydopamine, hexagonal boron nitride, hydroxylated carbon nanotubes, and MXene are configured into a solution with deionized water or distilled water according to a mass ratio of 1:1, 1:2, or 1:4, and ultrasonicated for 30 - 80 minutes to obtain a dispersion. The dispersion and the resin with specific toughening function are poured into the above-mentioned preform B, stirred for 10 - 60 minutes, and fully mixed. The non-dried toughened fiber felt is prepared by suction filtration, which is called preform C.

[0019] Further, 2 - 20 parts of MOFs (metal-organic frameworks) are configured into a solution and evenly sprayed on the preform C through an airbrush.

[0020] Further, the preform C is prepared according to the above method. The two non-dried toughened layers after spraying are adhered through physical and mechanical actions to form a complete-structured toughened layer, which is sent into a flat dryer at 30 - 80 °C for drying for 15 - 90 minutes.

[0021] Further, the surface weight of the prepared toughened fiber felt is 10 - 200 g / m 3 , and the thickness is 0.05 - 2 mm.

[0022] Further, according to the above method, multiple toughened fiber felts are prepared. The prepared toughened fiber felts are stored in a dry environment for the next composite material preparation process.

[0023] Further, pretreatment of the core fiber reinforcement: Mineral fibers such as carbon fiber and silicon carbide are selected as the main body of the composite material. Weigh 50 - 100 parts of the fiber, immerse the fiber in hydrochloric acid or sulfuric acid with a concentration of 2 - 10 mol / L for 10 - 60 minutes, then wash it with water until neutral, and then wash it three times with absolute ethanol, and dry it at 30 - 90 °C for 30 - 120 minutes to remove the auxiliaries and impurities on the fiber, which is beneficial for better bonding between the toughened layer and the resin in the molding process.

[0024] Step three: The toughened composite material is prepared by the VARTM molding process. The toughened fiber felt (skin) and the fiber core material need to be assembled and laid, and then the resin is infiltrated and cured under the action of vacuum negative pressure.

[0025] Further, the fiber core material, toughened fiber felt, release cloth, breather felt, flow guide net, absorbent felt, and vacuum bag are cut to appropriate sizes, and they are simply cleaned with a blower and then set aside. Since the carbon fiber cloth is relatively thick and not conducive to the flow of the resin, its four sides are cut at 45° to assist the resin in filling and flowing.

[0026] Further, tempered glass is selected as the single-sided mold, and a liquid release agent is applied to the surface and air-dried for standby.

[0027] Further, a toughening layer - fiber substrate (4 - 20 layers) - toughening layer is placed in sequence from bottom to top, with at least one toughening layer. Subsequently, the main structure is assembled and placed on the mold.

[0028] Further, a release cloth, a breather felt, and a flow net are sequentially laid on the main structure. The above-mentioned tooling is integrally sealed with a sealant, and two interfaces with opposite positions are reserved. One end is connected to a vacuum pump through a buffer tank, and the other end is sealed for standby.

[0029] Further, the airtightness of the mold is checked, with the criterion of maintaining a pressure of 0.1 MPa for 30 min.

[0030] Further, the above-mentioned standby port is connected to the prepared resin, and the vacuum pump valve is opened; the resin then starts to infiltrate the main structure. After curing, the mold is taken out to obtain the prepared fiber-reinforced and toughened composite material.

[0031] Preferably, a preparation method for a multi-scale interface toughened resin-based composite material structure includes the following steps:

[0032] 1) Put 50 - 100 parts by weight of surface-treated glass fibers into a fiber dissociator, add 10 - 50 parts by weight of binder and 5 - 20 parts by weight of antistatic agent, and stir to obtain preform A;

[0033] In step 1), the preparation of the surface-treated glass fibers specifically includes:

[0034] Place the glass fibers in a muffle furnace at 450°C to 550°C for heat preservation for 30 - 90 min, then disperse them in acetone or methyl ethyl ketone, perform ultrasonic surface cleaning, wash them with ethanol and deionized water respectively, and then transfer them to an oven for drying and collection to obtain the surface-treated glass fibers.

[0035] More preferably, place the glass fibers in a muffle furnace at 500°C for heat preservation for 60 min.

[0036] Preferably, perform ultrasonic surface cleaning for 3 - 5 h, and more preferably, perform ultrasonic surface cleaning for 4 h.

[0037] Preferably, wash with ethanol and deionized water three times respectively to remove acetone.

[0038] Preferably, then transfer them to an oven at 55°C to 65°C for drying and collection, and more preferably, then transfer them to an oven at 60°C for drying and collection.

[0039] Preferably, the binder is preferably 10 to 30 parts of polyethylene oxide (PEO), and more preferably 20 parts of polyethylene oxide (PEO).

[0040] Preferably, the antistatic agent is preferably 3 to 10 parts of a cationic antistatic agent, and more preferably 5 parts.

[0041] 2) Prepare a solution by mixing 10 to 20 parts by weight of metal particles with deionized water in a mass ratio of 1:1.5 to 3, and mix it with preform A to prepare preform B;

[0042] 3) Prepare a solution by mixing 10 - 60 parts by weight of nanosheets with deionized water in a mass ratio of 1:1.5 to 3, and ultrasonically disperse it to obtain a dispersion. Pour the dispersion and 6 - 12% wt of a toughening functional resin relative to the dispersion into the above preform B, stir, and mix well. Through the papermaking process, prepare an undried toughened fiber mat - preform C. Evenly spray 10 - 40 parts of MOFs metal-organic framework on preform C to obtain a toughening layer. Bond two toughening layers through their physical and mechanical actions, and send them into a flat dryer for drying to obtain a toughened mat;

[0043] 4) Place 30 - 100 parts of fiber reinforcement into organosilicon-modified waterborne polyurethane resin for surface modification, take it out after impregnation to obtain a carbon fiber substrate. Place the bottom toughened mat, carbon fiber substrate, and surface toughening layer from bottom to top in sequence to complete the assembly of the main structure. Then, lay a release cloth, a breather mat, and a flow net on the main structure in sequence, and use a sealant to seal the above tooling as a whole. Connect one end to a vacuum pump through a buffer tank, and connect the other port to 150 - 200 parts of epoxy resin prepared in advance. Uniformly mix the epoxy resin with a curing agent, open the vacuum pump valve, and after the resin is completely infiltrated and cured, take out the mold to obtain the prepared fiber-reinforced composite material.

[0044] In step 2), the metal particles (Al, Cu, Ni, Fe, Ag), preferably (preferably Ni nanoparticles) 15 parts.

[0045] The nanosheets are preferably 10 parts by weight (5 - 15 parts by weight) of carbon nanotubes.

[0046] In step 3), the resin with toughening function (preferably organosilicon-modified waterborne polyurethane resin).

[0047] The MOFs metal-organic framework is preferably 10 parts of metal-organic framework (ZIF-8), prepared into a solution, and evenly sprayed on preform C through an airbrush.

[0048] The drying conditions are: send it into a flat dryer at 50 - 70 °C and dry for 20 - 60 min. More preferably, send it into a flat dryer at 60 °C and dry for 30 - 45 min.

[0049] In step 4), 30 - 100 parts of fiber reinforcement, and the fiber reinforcement is preferably carbon fiber.

[0050] There is 1 layer of bottom toughening felt in the main structure.

[0051] The carbon fiber base material is 12 - 18 layers.

[0052] There is 1 layer of surface toughening layer in the main structure.

[0053] Epoxy resin is preferably 100 epoxy resins (LY, 1572, Huntsman Advanced Materials (Guangdong) Co., Ltd.), and 25 parts of supporting curing agent.

[0054] Compared with the prior art, the present invention has the following advantages:

[0055] For the fiber - toughened composite material prepared by the present invention, after functional modification of the fiber - toughened layer, the problem that the fiber - toughened layer and the composite material core material are delaminated due to the poor bonding force between the fiber and the resin, which seriously affects the mechanical properties of the composite material, is greatly improved. The prepared composite material shows excellent mechanical properties under bending, tensile and impact tests. Compared with the control group, under the optimal ratio, the bending performance can increase by up to 65.3%, the tensile strength can increase by up to 68.4%, and the impact strength can increase by up to 60.4%. The method steps of the present invention are simple, have good controllability, can realize stable and continuous production, can improve the bonding force between the fiber and the resin interface, maximize its mechanical properties, achieve energy conservation and consumption reduction, and sustainable development, and have good development prospects. Brief Description of the Drawings

[0056] Figure 1 It is the composite material structure design and the composite material preparation flow chart;

[0057] Figure 2 It is the VARTM process flow chart, where 1 - mold; 2 - laminate; 3 - bar; 4 - release cloth; 5 - sealant; 6 - guide tube; 7 - guide net; 8 - isolation film; 9 - equalizing plate; 10 - breather felt; 11 - vacuum bag; 12 - vacuum valve group; Detailed Embodiments

[0058] The present invention designs a sandwich multi - interlayer structure, with the fiber reinforcement as the "core" and the toughened fiber layer as the "skin", and prepares the composite material through the VARTM molding process. The shown structure from top to bottom is: fiber - toughened layer - core material - fiber - toughened layer. The structure is as Figure 1 shown.

[0059] The VARTM molding process flow is as Figure 2As shown below. First, tempered glass is selected as the single-sided mold 1, and a layer of liquid release agent is applied on its surface and air-dried for later use. Subsequently, the fiber core material, toughened fiber felt, release cloth, breather felt, flow guide net, resin absorption felt, and vacuum bag are cut to appropriate sizes, and after being simply cleaned with a blower, they are ready for use. Since the carbon fiber cloth is relatively thick and not conducive to the flow of resin, 45° cuts are made around its perimeter to assist the resin in filling the mold and flowing. The toughening layer - fiber substrate - toughening layer are placed in sequence from bottom to top to complete the assembly of the main structure, forming the laminate 2, which is placed on the mold 1. The retaining bar 3 is placed to keep the laminate 2 fixed. Further, the release cloth 4 is laid on the laminate 2 in sequence, sealant 5 is pasted around the mold, the flow guide tube 6 is laid around the laminate 2, and at the same time, the release cloth 4 and the flow guide net 7 are laid on the flow guide tube 6. The isolation film 8 is neatly laid on the release cloth 4, the uniform pressure plate 9 is placed, and finally a layer of breather felt 10 is placed, the vacuum bag 11 is laid, the flow guide tube 6 is connected to the resin tube, the vacuum bag film 44 is sealed, the vacuum valve group 12 is installed, the above-mentioned tooling is hermetically sealed with the sealant 5, and two interfaces with opposite positions are reserved. One end is connected to the vacuum pump through a buffer tank, and the other end is sealed for later use. The air tightness of the mold is checked, with the criterion of maintaining a pressure of 0.1 MPa for 30 minutes. Finally, the above-mentioned reserved port is connected to the prepared resin, and the vacuum pump valve is opened; the resin then starts to infiltrate the main structure. After curing, the mold is taken out to obtain the prepared fiber-reinforced composite material.

[0060] The preparation method of the metal-organic framework ZIF-8 is as follows: First, 2.95 g of Zn(NO3)2·6H2O and 6.5 g of 1,2-dimethylimidazole are weighed with an electronic balance. The two raw materials are respectively added to 200 ml of ultrapure water, stirred at room temperature for 10 minutes under a magnetic stirrer, the two solutions are mixed, and stirring is continued for 40 minutes. After being repeatedly washed three times with ultrapure water and centrifuged (9000 r / min, 12 minutes), after washing and centrifuging, it is placed in an oven at 60 °C and dried for 12 hours to obtain the white powder of ZIF-8 (the molecular formula of 1,2-dimethylimidazole: C5H8N2, molecular weight is 96.13; the molecular formula of zinc nitrate hexahydrate: Zn(NO3)2·6H2O, molecular weight is 297.49, both are provided by Aladdin Reagent (Shanghai) Co., Ltd.).

[0061] In the example, the polyethylene oxide PEO used is a product of Guangzhou Lihou Trading Co., Ltd. with a molecular weight of 1,000,000.

[0062] In the example, the antistatic agent is a cationic antistatic agent (polyquaternium-11, Shandong Baiqian Chemical Co., Ltd.).

[0063] In the example, the nanosheet material is multi-walled carbon nanotubes (outer diameter 8 - 15 nanometers, length 50 μm, Aladdin Reagent (Shanghai) Co., Ltd.).

[0064] The glass fiber in the example (China National Bluestar Group Co., Ltd., 562A chopped glass fiber).

[0065] The silicone-modified waterborne polyurethane resin in the example is the product of Jining Tangyi Chemical Co., Ltd., 1910R.

[0066] In the following examples, unless otherwise specified, all parts mentioned are parts by mass.

[0067] Example 1

[0068] A multi-scale interface toughened resin matrix composite structure design and its preparation method: Weigh the glass fiber, place the glass fiber in a muffle furnace at 500 °C for 60 min to remove some surface impurities. The treated glass fiber is dispersed in acetone, and surface cleaning is carried out by ultrasonic for 4 h. Then it is washed three times with ethanol and deionized water respectively to remove acetone, and then transferred to an oven at 60 °C for drying and collection.

[0069] Weigh 50 parts of the surface-treated glass fiber, put it into a 1000 ml fiber dissolver, add 20 parts of binder (polyethylene oxide (PEO)) and 5 parts of antistatic agent (cationic antistatic agent), and stir for 5 min to obtain preform A;

[0070] Prepare a solution of 15 parts of metal particles (Ni nanoparticles) and deionized water according to a mass ratio of 1:2, and mix it with preform A to prepare preform B; Prepare a solution of 10 parts of nanosheets (carbon nanotubes) and deionized water according to a mass ratio of 1:2, and carry out ultrasonic for 45 min to obtain a dispersion. Pour the dispersion and a resin with a specific toughening function of 8% wt relative to the mass of the dispersant (silicone-modified waterborne polyurethane resin) into the above preform B, stir for 30 min to fully mix, and prepare an undried toughened fiber mat - preform C through the traditional papermaking process. Prepare a solution of 10 parts of MOFs metal-organic framework (metal-organic framework (ZIF-8)), and evenly spray it on preform C through an air pump airbrush. Prepare another toughening layer according to the above placement, bond the two toughening layers through their own physical and mechanical actions, and send them into a 60 °C flat dryer for 40 min to dry for standby.

[0071] The toughened composite material is prepared by the VARTM molding process. The fiber reinforcement (carbon fiber) is placed in the organosilicon-modified waterborne polyurethane resin with different concentrations, specifically 8wt%, for surface modification. After impregnation for 15 minutes, it is taken out. 50 parts of the pretreated carbon fiber cloth and toughened fiber felt are placed on the tempered glass treated with the release agent. The toughened felt (1 layer) - carbon fiber substrate (15 layers) - toughened layer (1 layer) are placed in sequence from bottom to top to complete the assembly of the main structure. Subsequently, the release cloth, breather felt and flow net are laid on the main structure in sequence, and the above tooling is sealed integrally with the sealant. One end is connected to the vacuum pump through the buffer tank, and the other port is connected to the prepared epoxy resin (100 epoxy resins (LY, 1572, Huntsman Advanced Materials (Guangdong) Co., Ltd.)) and 25 parts of the matching curing agent). The epoxy resin and the curing agent are evenly mixed. The vacuum pump valve is opened. After the resin is completely infiltrated and cured, the mold is taken out to obtain the prepared fiber-reinforced composite material.

[0072] Through the three-point bending experiment, the flexural performance and energy absorption during the bending process of the composite material are characterized; through the five-notch simply supported beam impact test, the impact toughness and absorption rate of the composite material are characterized; through the short beam shear test, the bonding degree between the layers of the composite material is characterized. The composite material is cut into the standard sample size for mechanical testing (bending - test standard ISO 178, size 50mm×10mm×2mm; tensile - test standard ISO 527, size 200mm×25mm×2mm; impact - test standard - ISO 179, size 50mm×10mm×2mm). Compared with the control group (Example 5), the flexural strength is increased by 86.5%, the impact strength is increased by 63.2%, the interlaminar shear strength is increased by 78.8%, and the tensile strength is increased by 58.3%. The specific data are shown in Table 1.

[0073] Example 2

[0074] Multi-scale interface toughened resin matrix composite structure design and its preparation method: Weigh 100 parts of glass fiber, place the glass fiber in a muffle furnace at 500 °C for 60 min to remove part of the surface impurities. The treated glass fiber is dispersed in acetone and ultrasonically cleaned for 4 h. Then it is washed three times with ethanol and deionized water respectively to remove acetone, and then transferred to an oven at 60 °C for drying and collection. Weigh 50 parts of the surface-treated glass fiber, put it into a 1000 ml fiber dissociator, add 10 - 50 parts of binder, specifically 20 parts of polyethylene oxide (PEO), and 5 - 20 parts of antistatic agent, specifically 5 parts of cationic antistatic agent, and stir for 5 min to obtain preform A; Mix 10 - 30 parts of metal particles (Al, Cu, Ni, Fe, Ag), specifically 15 parts of Al nanoparticles, with deionized water according to a mass ratio of 1:2 to prepare a solution, and mix it with preform A to prepare preform B; Mix 10 - 60 parts of nanosheets, specifically 10 parts of carbon nanotubes, with deionized water according to a mass ratio of 1:2 to prepare a solution, and ultrasonically disperse it for 45 min to obtain a dispersion. Pour the dispersion and 6% wt of resin with specific toughening function (specifically organosilicon-modified waterborne polyurethane resin) into the above preform B, stir for 30 min to mix well, and prepare an undried toughened fiber mat - preform C through traditional papermaking process. Mix 10 - 40 parts of MOFs metal-organic frameworks, specifically 10 parts of metal-organic framework (ZIF-8), into a solution, and evenly spray it on preform C through an airbrush. Prepare another toughening layer according to the above method, bond the two toughening layers through their physical and mechanical actions, and send them into a 60 °C flat dryer for 30 - 45 min to dry for standby. Use the VARTM molding process to prepare the toughened composite material. Put the fiber reinforcement, specifically carbon fiber, into organosilicon-modified waterborne polyurethane resin with different concentrations, specifically 6 wt%, for surface modification, take it out after impregnation for 15 min. Place 50 parts of the pretreated carbon fiber cloth and the toughened fiber mat on the tempered glass treated with a release agent, and place the toughened mat (1 layer) - carbon fiber substrate (15 layers) - toughening layer (1 layer) from bottom to top in sequence to complete the assembly of the main structure. Then lay a release cloth, a breather mat and a flow net on the main structure in sequence, seal the above tooling as a whole with a sealant, connect one end to a vacuum pump through a buffer tank, and connect the other port to 150 - 200 parts of epoxy resin, specifically 100 parts of epoxy resin (LY, 1572, Huntsman New Materials (Guangdong) Co., Ltd.), and 25 parts of curing agent. Mix the epoxy resin and the curing agent evenly, open the vacuum pump valve, and after the resin is completely infiltrated and cured, take out the mold to obtain the prepared fiber-reinforced composite material.

[0075] Through three-point bending tests, the flexural properties and energy absorption during the bending process of the composite materials were characterized; through five-notch simply supported beam impact tests, the impact toughness and absorption rate of the composite materials were characterized; through short beam shear tests, the degree of bonding between layers of the composite materials was characterized. The composite materials were cut into the standard specimen sizes for mechanical tests (bending - test standard ISO 178, size 50 mm × 10 mm × 2 mm; tensile - test standard ISO 527, size 200 mm × 25 mm × 2 mm; impact - test standard - ISO 179, size 50 mm × 10 mm × 2 mm). Compared with the control group (Example 5), the flexural strength of the prepared composite materials increased by 65.7%, the impact strength increased by 57.7%, the interlaminar shear strength increased by 59.6%, and the tensile strength increased by 45.8%. The specific data are shown in Table 1.

[0076] Example 3

[0077] A multi-scale interface toughened resin matrix composite structure design and its preparation method: Weigh 100 parts of glass fiber, place the glass fiber in a muffle furnace at 500 °C for 60 minutes to remove some surface impurities. The treated glass fiber is dispersed in acetone, and ultrasonic surface cleaning is carried out for 4 hours. Then it is washed three times with ethanol and deionized water respectively to remove acetone, and then transferred to an oven at 60 °C for drying and collection. Weigh 50 parts of the surface-treated glass fiber, put it into a 1000 ml fiber dissociator, add 10 - 50 parts of binder, specifically 20 parts of polyethylene oxide (PEO), and 5 - 20 parts of antistatic agent, specifically 5 parts of cationic antistatic agent, and stir for 5 minutes to obtain preform A; Prepare a solution by mixing 10 - 30 parts of metal particles (Al, Cu, Ni, Fe, Ag), specifically 15 parts of (Ag nanoparticles), with deionized water in a mass ratio of 1:2, and mix it with preform A to prepare preform B; Prepare a solution by mixing 10 - 60 parts of nanosheets, specifically 10 carbon nanotubes, with deionized water in a mass ratio of 1:2, and ultrasonicate for 45 minutes to obtain a dispersion. Pour the dispersion and a 4%wt resin with a specific toughening function (specifically organosilicon-modified waterborne polyurethane resin) into the above preform B, stir for 30 minutes to mix well, and prepare an undried toughened fiber mat - preform C through the traditional papermaking process. Prepare a solution of 10 - 40 parts of MOFs metal-organic frameworks, specifically 10 parts of metal-organic framework (ZIF-8), and spray it evenly on preform C through an airbrush. Prepare another toughening layer according to the above method, bond the two toughening layers through their own physical and mechanical actions, and send them into a 60 °C flat dryer for 30 - 45 minutes to dry for later use. Use the VARTM molding process to prepare the toughened composite material. Put the fiber reinforcement, specifically carbon fiber, into an organosilicon-modified waterborne polyurethane resin with different concentrations, specifically 4wt%, for surface modification, take it out after impregnation for 15 minutes. Place 50 parts of the pretreated carbon fiber cloth and the toughened fiber mat on the tempered glass treated with a release agent, and place the toughened mat (1 layer) - carbon fiber substrate (15 layers) - toughening layer (1 layer) from bottom to top in sequence to complete the assembly of the main structure. Then lay a release cloth, a breather mat and a flow net on the main structure in sequence, seal the above tooling as a whole with a sealant, connect one end to a vacuum pump through a buffer tank, and connect the other port to 150 - 200 parts of epoxy resin, specifically 100 parts of epoxy resin (LY, 1572, Huntsman New Materials (Guangdong) Co., Ltd.), and 25 parts of curing agent. Mix the epoxy resin and the curing agent evenly, open the vacuum pump valve, and after the resin is completely infiltrated and cured, take out the mold to obtain the prepared fiber-reinforced composite material.

[0078] Through three-point bending tests, the flexural properties and energy absorption during the bending process of the composite materials were characterized; through five-notch simply supported beam impact tests, the impact toughness and absorption rate of the composite materials were characterized; through short beam shear tests, the bonding degree between the layers of the composite materials was characterized. The composite materials were cut into the standard sample sizes for mechanical tests (bending - test standard ISO 178, size 50 mm × 10 mm × 2 mm; tensile - test standard ISO 527, size 200 mm × 25 mm × 2 mm; impact - test standard - ISO 179, size 50 mm × 10 mm × 2 mm). Compared with the control group (Example 5), the flexural strength of the prepared composite materials increased by 62.7%, the impact strength increased by 53.8%, the interlaminar shear strength increased by 51.9%, and the tensile strength increased by 42.3%. The specific data are shown in Table 1.

[0079] Example 4

[0080] A multi-scale interface toughened resin-based composite material structure design and preparation method: weigh 100 parts of glass fiber, place the glass fiber in a 500°C muffle furnace for 60 minutes, remove some impurities on the surface, disperse the treated glass fiber in acetone, perform 4 hours of ultrasonic surface cleaning, wash three times with ethanol and deionized water respectively, remove acetone, and then transfer to a 60°C oven for drying and collection. Weigh 50 parts of surface-treated glass fiber, put it into a 1000ml fiber disintegrator, add 10-50 parts of adhesive, specifically 20 parts of polyethylene oxide (PEO), 5-20 parts of antistatic agent, specifically 5 parts of cationic antistatic agent, stir for 5 minutes, and prepare preform A; prepare a solution of 10-30 parts of metal particles (Al, Cu, Ni, Fe, Ag), specifically 15 parts of (Fe nanoparticles) with deionized water according to a mass ratio of 1:2, and mix with preform A to prepare preform B; prepare 10-60 parts of nanosheets, specifically 10 carbon The nanotubes and deionized water were prepared into a solution in a mass ratio of 1:2, and ultrasonicated for 45 minutes to obtain a dispersion. The dispersion and 2%wt of a resin with a specific toughening function (specifically, a silicone-modified waterborne polyurethane resin) were poured into the preform B, stirred for 30 minutes, and fully mixed. An undried toughened fiber felt, a preform C, was prepared by a traditional papermaking process. 10-40 parts of a MOFs metal organic framework, specifically 10 parts of a metal organic framework (ZIF-8) (prepared into a solution, was evenly sprayed on the preform C through an air pump spray pen, and another preform was prepared according to the above placement. The two toughening layers are bonded by their own physical and mechanical action, and then sent to a 60°C flat plate dryer for 30-45 minutes to dry for use. The toughened composite material is prepared by VARTM molding process. The fiber reinforcement, specifically carbon fiber, is placed in different concentrations of silicone-modified waterborne polyurethane resin, specifically 2wt%, for surface modification. After immersion for 15 minutes, take it out and place 50 parts of pre-treated carbon fiber cloth and toughened fiber felt on tempered glass treated with release agent. From bottom to top, toughened felt (1 layer) - carbon fiber substrate (15 layers) are placed in sequence. )—toughening layer (1 layer), complete the assembly of the main structure, and then lay the demoulding cloth, breathable felt and guide net on the main structure in turn, use sealant to seal the above-mentioned tooling as a whole, one end is connected to the vacuum pump through the buffer tank, and the other end is connected to 150-200 parts of the prepared epoxy resin, specifically 100 epoxy resin (LY, 1572, Huntsman New Materials (Guangdong) Co., Ltd.)), 25 parts of curing agent, mix the epoxy resin and the curing agent evenly, open the vacuum pump valve, and after the resin is completely infiltrated and cured, take out the mold to obtain the prepared fiber-reinforced composite material.

[0081] Through three-point bending tests, the flexural properties and energy absorption during the bending process of the composite materials were characterized; through five-notch simply supported beam impact tests, the impact toughness and absorption rate of the composite materials were characterized; through short beam shear tests, the interfacial bonding degree of the composite materials was characterized. The composite materials were cut into the standard sample sizes for mechanical tests (bending - test standard ISO 178, size 50 mm × 10 mm × 2 mm; tensile - test standard ISO 527, size 200 mm × 25 mm × 2 mm; impact - test standard ISO 179, size 50 mm × 10 mm × 2 mm). Compared with the control group (Example 5), the flexural strength of the prepared composite materials increased by 54.9%, the impact strength increased by 50.2%, the interlaminar shear strength increased by 46.1%, and the tensile strength increased by 34.4%. The specific data are shown in Table 1.

[0082] Example 5

[0083] A structural design and preparation method of a multi-scale interface toughened resin matrix composite material: Weigh 50 parts of glass fiber and put it into a 1000 ml fiber dissociator, add 10 - 50 parts of binder, specifically 20 parts, and 10 - 50 parts of antistatic agent, specifically 10 parts of cationic antistatic agent, stir for 25 - 30 min, prepare another toughening layer according to the above placement, bond the two toughening layers through physical and mechanical actions, and send them into a 60 °C flat dryer for 30 - 45 min to dry for standby.

[0084] The toughened composite material was prepared by the VARTM molding process. Place 80 - 100 parts of fiber core material, specifically 50 parts of carbon fiber and toughened fiber felt, on the tempered glass treated with mold release agent, and place the toughening felt - carbon fiber base material (15 layers) - toughening layer from bottom to top in sequence to complete the assembly of the main structure. Subsequently, place the release cloth, breather felt and flow net on the main structure in sequence, seal the above tooling as a whole with sealant, connect one end to a vacuum pump through a buffer tank, and connect the other port to 150 - 200 parts of resin that has been prepared, specifically 100 parts of epoxy resin (LY, 1572, Huntsman New Materials (Guangdong) Co., Ltd.), 25 parts of curing agent. Mix the epoxy resin and the curing agent evenly, open the vacuum pump valve, and after the resin is completely infiltrated and cured, take out the mold to obtain the prepared fiber toughened composite material.

[0085] Through three-point bending tests, the flexural properties and energy absorption during the bending process of the composite materials were characterized; through five-notch simply supported beam impact tests, the impact toughness and absorption rate of the composite materials were characterized; through short beam shear tests, the bonding degree between the layers of the composite materials was characterized. The composite materials were cut into the standard sample sizes for mechanical tests (bending - test standard ISO 178, size 50 mm × 10 mm × 2 mm; tensile - test standard ISO 527, size 200 mm × 25 mm × 2 mm; impact - test standard - ISO 179, size 50 mm × 10 mm × 2 mm). The flexural strength of the prepared composite materials was 502.3 MPa, the impact strength reached 860 KJ / m2, the interlaminar shear strength was 52 MPa, and the tensile strength was 622.3 MPa. The specific data are shown in Table 1.

[0086] Table 1 Specific data of the mechanical property tests of the composite materials

[0087]

[0088] By comparing with Example 5 (control group), it was found that after multi-scale toughening treatment of the toughening layer, the toughening effect of the composite materials was significantly improved. The flexural strength of the composite materials increased by 86.5%, the impact strength increased by 63.2%, the interlaminar shear strength increased by 78.8%, and the tensile strength increased by 58.3%. Different differences in the metal particles themselves would also affect the mechanical properties of the composite materials. Ni particles themselves had excellent flame retardant properties, and at the same time, like other metal particles, they had good toughening effects. Two-dimensional and three-dimensional materials were very helpful for the overall dispersion performance, reducing the risk of stress concentration caused by particle aggregation and affecting the mechanical properties. The addition of nano-materials greatly improved the interfacial bonding force between the fibers and the resin, and the delamination of the interface during the stress process was also significantly reduced. The sandwich-structured panel had a significant improvement in the ability to withstand bending, torsion, and various in-plane loads during the stress process. The present invention has good prospects in improving the structural performance of composite materials and expanding the application fields.

[0089] The specific embodiments described above further detailed the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a multi-scale interface toughened resin matrix composite material structure, characterized in that It includes the following steps: 1) Put 50-100 parts by weight of surface-treated glass fiber into a fiber dissolver, add 10-50 parts by weight of binder and 5-20 parts by weight of antistatic agent, and stir to obtain preform A; 2) Prepare a solution by mixing 10-20 parts by weight of metal particles with deionized water in a mass ratio of 1:1.5-3, and mix it with preform A to prepare preform B; 3) Prepare a solution by mixing 10-60 parts by weight of nanosheets with deionized water in a mass ratio of 1:1.5-3, and ultrasonically prepare a dispersion. Pour the dispersion and a resin with a toughening function of 6-12% wt relative to the dispersion into the above preform B, stir, and mix well. Through the papermaking process, prepare an undried toughened fiber mat - preform C. Evenly spray 10-40 parts of MOFs metal-organic framework on preform C to obtain a toughening layer. Bond two toughening layers through their own physical and mechanical actions, and send them into a flat dryer for drying to obtain a toughened mat; 4) Put the fiber reinforcement into an organosilicon-modified waterborne polyurethane resin for surface modification, take it out after impregnation to obtain a carbon fiber substrate. Place a bottom toughened mat, a carbon fiber substrate, and a surface toughening layer from bottom to top in sequence to complete the assembly of the main structure. Then lay a release cloth, a breather mat, and a flow guide net on the main structure in sequence. Use a sealant to seal the above tooling as a whole. Connect one end to a vacuum pump through a buffer tank, and connect the other port to the prepared epoxy resin. Open the vacuum pump valve. After the resin is completely infiltrated and cured, take out the mold to obtain the prepared fiber-reinforced composite material.

2. The preparation method of the multi-scale interface toughened resin matrix composite material structure according to claim 1, characterized in that In step 1), the preparation of the surface-treated glass fiber specifically includes: Place the glass fiber in a muffle furnace at 450°C - 550°C for heat preservation for 30-90 min, then disperse it in acetone or butanone, perform ultrasonic surface cleaning, wash it with ethanol and deionized water respectively, and then transfer it to an oven for drying and collection to obtain the surface-treated glass fiber.

3. The preparation method of the multi-scale interface toughened resin matrix composite material structure according to claim 2, characterized in that, In step 1), then transfer it to an oven at 55°C - 65°C for drying and collection.

4. The preparation method of the multi-scale interface toughened resin matrix composite material structure according to claim 1, characterized in that, In step 1), the binder is polyethylene oxide; The antistatic agent is a cationic antistatic agent.

5. The preparation method of the multi-scale interface toughened resin matrix composite material structure according to claim 1, characterized in that, In step 2), the metal particles are Al, Cu, Ni, Fe, or Ag.

6. The preparation method of the multi-scale interface toughened resin matrix composite material structure according to claim 1, wherein, In step 3), the nanosheets are carbon nanotubes; The resin with a toughening function is an organosilicon-modified waterborne polyurethane resin; The MOFs metal-organic framework is metal-organic framework ZIF-8.

7. The preparation method of the multi-scale interface toughened resin matrix composite material structure according to claim 1, characterized in that, In step 3), the drying conditions are: send it into a flat dryer at 50 - 70°C and dry it for 20-60 min.

8. The preparation method of the multi-scale interface toughened resin matrix composite material structure according to claim 1, characterized in that, In step 4), the fiber reinforcement is carbon fiber; In the main structure, there is 1 layer of bottom toughened mat, 12-18 layers of carbon fiber substrate, and 1 layer of surface toughening layer.

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