High-strength self-healing resin-based composite material and preparation and healing methods thereof

Abstract

The invention discloses a high-strength self-healing resin-based composite material as well as a preparation method and a healing method thereof, belongs to the technical field of resin-based composite materials, and solves the problems that a composite material in the prior art does not have a self-healing function and lacks an effective healing method. The method comprises the following steps: stirring and mixing liquid epoxy resin, solid epoxy resin and reactive polyurethane modified epoxy resin to obtain matrix resin; uniformly mixing a curing agent with matrix resin, and passing through a grinding machine for multiple times to obtain a healable epoxy resin matrix; preparing an adhesive film from the healable epoxy resin matrix, and then laminating the reinforced carbon fiber and the adhesive film to prepare a carbon fiber prepreg; preparing a carbon nanomaterial solution, spraying the carbon nanomaterial solution on one surface of the carbon fiber prepreg, and airing to prepare a modified prepreg; and cutting the modified prepreg, pressurizing and curing to obtain the high-strength self-healing resin-based composite material. The high-strength self-healing resin-based composite material disclosed by the invention is excellent in mechanical property and high in repairing efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of resin-based composite materials, and in particular to a high-strength self-healing resin-based composite material and a preparation method and a healing method thereof. Background Art

[0002] Resin-based composite materials occupy an important position in the aerospace field due to their light weight, high strength, and strong designability. Their usage has become an important indicator of the advanced nature of equipment. Composite structures will inevitably produce local damage and microcracks after molding or during use, which seriously affects the normal use of the material and shortens its service life, greatly increasing safety hazards and maintenance costs. If composite structures can repair minor damage in a timely and rapid manner through body repair, the above problems can be avoided, and high-reliability reuse of composite materials can be achieved, which is of great significance for improving the service life and maintenance capabilities of aerospace vehicle structures and reducing maintenance costs.

[0003] The resins used in traditional resin-based composite materials can be divided into two categories: thermosetting and thermoplastic. Among them, thermosetting resin matrices such as epoxy resins are widely used because of their good dimensional stability, mechanical properties and solvent resistance. However, due to the irreversible three-dimensional cross-linked structure in its polymer network, it is difficult to perform in-situ body repair when defects or damage occur in the composite material during molding or use, and the repair effect is not obvious. Thermoplastic resin-based composite materials have the advantages of high toughness, fatigue resistance, repeatable processing, and weldable repair, but their molding temperature is high, pressure is high, processability is poor, and the quality of composite components is unstable. Therefore, the existing resin-based composite material system can no longer meet the performance requirements of aircraft for repairability. The vitrimer resin matrix based on non-dissociative dynamic covalent bonds has both self-healing function and excellent mechanical and process properties, and is currently one of the main material solutions for achieving self-healing of composite materials. Although relevant research at home and abroad has made certain progress, it is still in the laboratory stage and there has been no report on its application in actual products. Specifically, the following problems exist: (1) It is difficult to take into account both the dynamic reversibility and mechanical and thermal properties of the resin, resulting in poor heat resistance and low mechanical strength. (2) The focus is on the study of resin properties and mechanisms, but the resin does not have the processability for practical engineering applications. There has been no research and development and application of prepreg resin systems with self-healing properties, which cannot meet the requirements of composite component molding or autoclave manufacturing. (3) There is a lack of effective methods for controlled healing of composite damage, and the existing hot press or oven heating methods cannot meet the requirements of actual engineering conditions. Summary of the invention

[0004] In view of the above situation, the present invention aims to provide a high-strength self-healing resin-based composite material and its preparation and healing method, which is used to solve one of the problems that existing composite materials do not have self-healing function, or the dynamic reversibility and mechanical and thermal properties of the resin are difficult to balance, and there is a lack of effective controllable healing methods for composite material damage.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] In one aspect, the present invention provides a method for preparing a high-strength self-healing resin-based composite material, comprising the following steps:

[0007] Step 1, stirring and mixing liquid epoxy resin, solid epoxy resin, and reactive polyurethane modified epoxy resin at 90-110° C. to obtain a matrix resin;

[0008] Step 2, the curing agent and the matrix resin are mixed evenly, and passed through a three-roll grinder for multiple times to obtain a curable epoxy resin matrix;

[0009] Step 3, making a healing epoxy resin matrix into a film, and then laminating the reinforced carbon fiber and the film to prepare a carbon fiber prepreg;

[0010] Step 4, ultrasonically dispersing the high thermal conductivity carbon nanomaterial in a solvent to prepare a carbon nanomaterial solution, spraying the carbon nanomaterial solution evenly on one side of the carbon fiber prepreg, and fully drying it to prepare a modified prepreg;

[0011] Step 5: Cut the modified prepreg, lay it in layers in a mold, and pressurize and cure it to obtain a high-strength self-healing resin-based composite material.

[0012] Furthermore, in step 1, the liquid epoxy resin is one or more of E44, E51, E54, F-44, F-51, TDE-85, and AG-80.

[0013] Furthermore, in step 1, the solid epoxy resin is one or more of E12, E20, E-21, JF-43, and JF-45.

[0014] Furthermore, in step 1, the mass ratio of the liquid epoxy resin, the solid epoxy resin and the reactive polyurethane modified epoxy resin is 40-80:20-60:5-10.

[0015] Furthermore, in step 2, the curing agent is a diborane-oxygen heterocyclic dianiline containing a dynamic borate ester bond bridge.

[0016] Furthermore, in step 2, the mass ratio of the liquid epoxy resin to the curing agent is controlled to be 40-80:20-50.

[0017] Furthermore, in step 3, the content of the healable epoxy resin matrix in the carbon fiber prepreg is controlled to be 38% to 42%.

[0018] Furthermore, in step 5, the curing process is: keep warm at 70-90°C for 0.5-1h, close the mold and pressurize, the curing pressure is 2-4MPa, heat to 140-160°C, and react for 2-3h.

[0019] The present invention also provides a high-strength self-healing resin-based composite material, which is prepared by the above-mentioned preparation method.

[0020] The present invention also provides a method for healing a high-strength self-healing resin-based composite material, comprising the following steps:

[0021] S1. Locate the specific location and size of composite material damage by CT or ultrasonic C-scan;

[0022] S2. Lead out metal wires from both ends of the damaged part by welding metal copper sheets and connect them to an external power source;

[0023] S3. Place the damaged composite material product in a vacuum bag, seal it with a sealing tape, and lead the power wire out from the sealing tape;

[0024] S4, evacuate the chamber and apply external voltage to the composite material, repair the damaged part under vacuum pressure and resistance heat, turn off the vacuum and voltage, remove the vacuum bag, and obtain a repaired composite material product.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] a) The preparation method of the high-strength self-healing resin-based composite material of the present invention adopts a formulation system of a hot-melt prepreg process. The prepared prepreg has good draping processability and a long room temperature application period, which can meet the needs of batch preparation and application, and fills the technical gap in the current engineering application field.

[0027] b) The high-strength self-healing resin-based composite material prepared by the present invention is designed by introducing highly conductive and thermally conductive carbon nanomaterials between layers, constructing a three-dimensional continuous conductive network of carbon nano-carbon fibers in the composite material, and applying an external voltage to the composite material to heat the damaged part of the composite material by utilizing the enhanced resistive thermal effect. At the same time, under certain vacuum pressure conditions, the resin at the damaged interface of the composite material can be re-fused through the exchange reaction of the borate ester bonds and the movement and rearrangement of the polymer chains, thereby achieving damage healing of the composite material without the aid of external heating equipment. The repair method is practical and efficient, with a repair efficiency of more than 84%, which is more in line with the working condition requirements of composite structure products during repair and has the feasibility of promotion and application.

[0028] c) The high-strength self-healing resin-based composite material prepared by the present invention can achieve efficient healing of molding defects and service damage, and has mechanical properties and heat resistance comparable to those of traditional thermosetting composite materials. For example, the 0° tensile strength of the high-strength self-healing resin-based composite material of the present invention is above 1920 MPa (e.g., 1920-2680 MPa), the 0° tensile modulus is above 120 GPa (e.g., 120-154 GPa), and the flexural strength is above 1710 MPa (e.g., 1710-2070 MPa). a), a flexural modulus of more than 115 GPa (for example, 115 to 151 GPa), an interlaminar shear strength of more than 101 MPa (for example, 101 to 108 MPa), a glass transition temperature Tg of 155 to 185°C, and a flexural strength of more than 1540 MPa (for example, 1540 to 1800 MPa) after the damaged sample is repaired; the high-strength self-healing resin-based composite material of the present invention can replace the existing epoxy resin system, improve the molding quality and qualified rate of complex structural parts, and greatly improve the reliability and safety of equipment use.

[0029] d) The healing method of the high-strength self-healing resin-based composite material of the present invention does not require the aid of external heating equipment, and the repair method is practical and efficient, and has the feasibility of popularization and application.

[0030] Other features and advantages of the present invention will be described in the following description, and part of them will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the contents particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0032] Figure 1 CT scan photos of the high-strength self-healing resin-based composite material sample of Example 1 before and after repair;

[0033] Figure 2 These are CT scan photos of the high-strength self-healing resin-based composite material sample of Example 2 before and after repair. DETAILED DESCRIPTION

[0034] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0035] The present invention provides a method for preparing a high-strength self-healing resin-based composite material, comprising the following steps:

[0036] Step 1, stirring and mixing liquid epoxy resin, solid epoxy resin, and reactive polyurethane modified epoxy resin at 90-110° C. to obtain a matrix resin;

[0037] Step 2, mixing the curing agent and the matrix resin evenly at a suitable temperature, and passing through a three-roll mill three times to obtain a healable epoxy resin matrix;

[0038] Step 3, making a healing epoxy resin matrix into a film, and then laminating the reinforced carbon fiber and the film to prepare a carbon fiber prepreg;

[0039] Step 4, ultrasonically dispersing the high thermal conductivity carbon nanomaterial in a solvent to prepare a uniform carbon nanomaterial solution, spraying the carbon nanomaterial solution uniformly on one side of the carbon fiber prepreg, and after fully drying, preparing a modified prepreg;

[0040] Step 5: Cut the modified prepreg, lay it in layers in a mold, and pressurize and cure it to obtain a high-strength self-healing resin-based composite material.

[0041] Specifically, in the above step 1, the liquid epoxy resin is one or more of E44, E51, E54, F-44, F-51, TDE-85, and AG-80.

[0042] Specifically, in the above step 1, the solid epoxy resin is one or more of E12, E20, E-21, JF-43, and JF-45.

[0043] Specifically, in the above step 1, the reactive polyurethane modified epoxy resin is mainly used for toughening purpose. Compared with externally added toughening agents such as rubber and thermoplastics, the advantages of using reactive polyurethane modified epoxy resin in the present invention are: 1. It avoids stress concentration caused by uneven dispersion of added toughening agents, ensuring good mechanical strength and toughness; 2. It can participate in the curing reaction, and the molecular chain segments formed by the toughening agent are also part of the dynamic cross-linked network, and participate in the dynamic exchange and rearrangement movement of the cross-linked network during the resin repair process, avoiding the restriction of the movement of resin molecular segments by the use of added toughening agents, thereby causing a decrease in self-healing efficiency.

[0044] Specifically, in the above step 1, it is considered that too much liquid epoxy resin will result in too low viscosity of the matrix resin at room temperature and no peeling property at room temperature; too little liquid epoxy resin will result in too high viscosity of the matrix resin at room temperature and no adhesion and laying property at room temperature. Therefore, in order to ensure that the viscosity of the matrix resin can meet the requirements of the prepreg molding process and has appropriate adhesion, laying and peeling properties at room temperature, the mass ratio of liquid epoxy resin, solid epoxy resin and reactive polyurethane modified epoxy resin is controlled to be 40-80:20-60:5-10.

[0045] Specifically, in the above step 1, the stirring and mixing is controlled to be uniform at 90-110°C, because in this temperature range, the solid epoxy resin can melt and can be uniformly blended with the liquid epoxy resin. If the temperature is too low, the solid epoxy resin cannot be completely melted and cannot be uniformly mixed; if the temperature is too high, the epoxy group will be thermally oxidized, affecting the quality of the matrix resin.

[0046] Specifically, in the above step 2, the curing agent is a diborane heterocyclic dianiline containing a dynamic borate ester bond bridge, and the curing agent can be any one or a combination of the following:

[0047]

[0048] Specifically, in the above step 2, the curing agent has a relatively high melting point (for example, a melting point of 200-230° C.) and a relatively low reactivity, which can ensure the room temperature storage stability of the prepared prepreg.

[0049] Specifically, in the above step 2, the curing agent and the base resin are uniformly mixed at 25-40°C.

[0050] Specifically, in the above step 2, in order to ensure the curing effect, the mass ratio of the liquid epoxy resin to the curing agent is controlled to be 40-80:20-50.

[0051] Specifically, in the above step 2, if the particle size of the curing agent is too large, the curing agent will be unevenly dispersed and the resin will not be completely cured; if the particle size of the curing agent is too small, the process will be difficult to implement and the cost will be too high. Therefore, in order to facilitate the grinding and dispersion of the curing agent in the epoxy matrix, the particle size of the curing agent is controlled to be 2 to 5 μm.

[0052] Specifically, in the above step 2, the viscosity of the healable epoxy resin matrix at 60-80° C. is 5000-30000 mP.S, which can meet the viscosity requirement of the resin coating process.

[0053] Specifically, in the above step 3, the reinforced carbon fiber may be high-strength carbon fiber and its fabric form, and the reinforced carbon fiber is preferably at least one of T700, T800, T1000h and T1100 carbon fiber.

[0054] Specifically, in the above step 3, the content of the healable epoxy resin matrix in the carbon fiber prepreg is controlled to be 38% to 42%.

[0055] Specifically, in the above step 3, the carbon fiber prepreg fiber surface density is 130-140 g / m 2 .

[0056] Specifically, in the above step 3, the coating temperature is 60-80°C, and the laminating temperature is 70-90°C.

[0057] Specifically, in the above step 3, the carbon fiber prepreg has a shelf life of ≥30 days at room temperature.

[0058] Specifically, in the above step 4, the high thermal conductivity carbon nanomaterial is preferably one or a combination of carbon nanotubes or graphene nanosheets.

[0059] Specifically, in the above step 4, in order to ensure the best thermal and electrical conductivity, the length of the carbon nanotubes is controlled to be 10-200 μm and the diameter is 5-100 nm, and the size of the graphene nanosheets is preferably 0.5-1.5 nm in thickness and 0.5-5 μm in diameter.

[0060] Specifically, in the above step 4, the solvent is preferably ethanol or acetone. Considering that if the mass fraction of the carbon nanomaterial in the carbon nanomaterial solution is too high, the carbon nanomaterial will agglomerate and cannot be effectively and evenly dispersed; if the mass fraction of the carbon nanomaterial is too low, the spraying amount of the carbon nanomaterial solution will be too large, resulting in excessive solvent content in the prepreg, slow volatilization, and affecting the molding quality. Therefore, in order to ensure uniform dispersion of the carbon nanomaterial and uniform spraying amount on the prepreg, which is conducive to the preparation of the modified prepreg, the mass fraction of the carbon nanomaterial in the carbon nanomaterial solution is controlled to be 2% to 5%.

[0061] Specifically, in the above step 4, the carbon nano material solution is sprayed onto the surface of the carbon fiber prepreg by uniform spraying, and the mass percentage of the carbon nano material in the healable epoxy resin matrix is ​​1% to 3%.

[0062] Specifically, in the above step 5, in order to control the viscosity of the resin at the curing pressure point, pressurize at the most appropriate viscosity to ensure the production of high-quality products. After in-depth research, the inventors controlled the curing process as follows: keep warm at 70-90°C for 0.5-1h, close the mold and pressurize, the curing pressure is 2-4MPa, heat to 140-160°C, and react for 2-3h.

[0063] The present invention also provides a high-strength self-healing resin-based composite material, which is prepared by the above preparation method. The 0° tensile strength of the above-mentioned high-strength self-healing resin-based composite material is 1920MPa or more (for example, 1920-2680MPa), the 0° tensile modulus is 120GPa or more (for example, 120-154GPa), the flexural strength is 1710MPa or more (for example, 1710-2070MPa), the flexural modulus is 115GPa or more (for example, 115-151GPa), the interlaminar shear strength is 101MPa or more (for example, 101-108MPa), the glass transition temperature Tg is 155-185°C, the flexural strength of the damaged sample after repair is 1540MPa or more (for example, 1540-1800MPa), and the repair efficiency is 84% ​​or more (for example, 84%-90%).

[0064] The present invention also provides a method for healing a high-strength self-healing resin-based composite material, comprising the following steps:

[0065] S1. Locate the specific location and size of composite material damage by CT or ultrasonic C-scan;

[0066] S2. Lead out metal wires from both ends of the damaged part by welding metal copper sheets and connect them to an external power source;

[0067] S3. Place the damaged composite material product in a vacuum bag, seal it with a sealing tape, and lead the power wire out from the sealing tape;

[0068] S4, evacuate the chamber and apply external voltage to the composite material, repair the damaged part under vacuum pressure and resistance heat, turn off the vacuum and voltage, remove the vacuum bag, and obtain a repaired composite material product.

[0069] Specifically, in the above S4, the vacuum degree is not less than -0.09MPa, the externally applied voltage parameters are adjusted according to the size and depth of the damage, the voltage can be optimized to be 20-400V, the center temperature of the damaged part is controlled between 160-200°C, and the repair time is 20-60min.

[0070] Compared with the prior art, the preparation method of the high-strength self-healing resin-based composite material of the present invention adopts the formulation system of the hot-melt prepreg process. The prepared prepreg has good draping processability and a long room temperature application period, which can meet the needs of batch preparation and application, filling the technical gap in the current engineering application field.

[0071] The high-strength self-healing resin-based composite material prepared by the present invention is designed by introducing highly conductive and thermally conductive carbon nanomaterials between layers, constructing a three-dimensional continuous conductive network of carbon nano-carbon fibers in the composite material, applying an external voltage to the composite material, and utilizing the enhanced resistive thermal effect to heat the damaged portion of the composite material, and at the same time, under certain vacuum pressure conditions, the resin at the damaged interface of the composite material can be re-fused through the exchange reaction of borate bonds and the movement rearrangement of polymer chains, thereby achieving damage healing of the composite material without the aid of external heating equipment. The repair method is practical and efficient, with a repair efficiency of more than 84%, which is more in line with the working condition requirements of composite structure products during repair and has the feasibility of popularization and application.

[0072] The high-strength self-healing resin-based composite material prepared by the present invention can achieve efficient healing of molding defects and service damage, and has mechanical properties and heat resistance comparable to traditional thermosetting composite materials. It can replace the existing epoxy resin system, improve the molding quality and pass rate of complex structural parts, and greatly enhance the reliability and safety of equipment use.

[0073] Example 1

[0074] This embodiment provides a high-strength self-healing resin-based composite material and a preparation and healing method thereof.

[0075] The preparation method of the high-strength self-healing resin-based composite material of this embodiment comprises the following steps:

[0076] Step 1, weighing 60 parts of bisphenol A type liquid epoxy resin E51, 40 parts of solid epoxy resin E20, and 5 parts of reactive polyurethane modified epoxy resin according to their mass parts, stirring and mixing at 100° C. to obtain a base resin;

[0077] Step 2: Weigh 36 parts of curing agent according to the mass fraction, mix it evenly with the above-mentioned base resin at 30°C, and pass it through a three-roll grinder three times to obtain a curable epoxy resin base. The structural formula of the curing agent is as follows:

[0078]

[0079] Step 3: Prepare a film of the healable epoxy resin matrix, and then laminate the T700 unidirectional carbon fiber and the film to prepare a carbon fiber unidirectional prepreg. The mass content of the healable epoxy resin matrix in the prepreg is controlled at 40%, and the prepreg fiber surface density is 135g / m 2 , coating temperature is 70℃, laminating temperature is 80℃;

[0080] Step 4: Weigh 3 parts of carbon nanotubes (length 50-100 μm, diameter 10-20 nm) and ultrasonically disperse them in 100 parts of ethanol solvent to prepare a uniform 3 wt% carbon nanotube ethanol solution. Spray the carbon nanotube material solution evenly on one side of the carbon fiber prepreg, 1 m 2 The spraying amount of the prepreg is 60 ml, the proportion of the carbon nanotubes in the healable epoxy resin matrix is ​​2 wt %, and after being fully dried, a modified prepreg is prepared;

[0081] Step 5: Cut the prepreg into the required shape, lay the layers in the mold, and use the curing process of 80℃ / 0.5h+150℃ / 2h and the curing pressure of 2MPa. After cooling to room temperature, demould to obtain a high-strength self-healing resin-based composite material. The basic mechanical properties and thermal properties of the high-strength self-healing resin-based composite material were tested, and the results are shown in Table 1.

[0082] The healing methods of high-strength self-healing resin-based composite materials include:

[0083] Step 1: Perform a bending fatigue test on the composite material according to standard HB7624 until the composite material fails to form a delamination structure;

[0084] Step 2: locate the specific damaged part and size of the composite material by ultrasonic C scanning, lead out metal wires at both ends of the damaged part by welding metal copper sheets, and connect them to an external power supply;

[0085] Step 3: Place the damaged composite material sample in a vacuum bag, seal it with sealing tape, and lead the power wire out of the sealing tape; evacuate the vacuum pressure to 0.096MPa, apply a voltage of 40V, detect the surface temperature at about 180°C, and let it stand for repair for 30 minutes; turn off the vacuum and voltage, remove the vacuum bag, and obtain the repaired composite material product.

[0086] The flexural strength of the repaired composite material was tested, and the repair efficiency (repaired flexural strength / original flexural strength) was calculated. The results are shown in Table 1.

[0087] Table 1 Performance data of the composite material of Example 1

[0088]

[0089] Example 2

[0090] This embodiment provides a high-strength self-healing resin-based composite material and a preparation and healing method thereof.

[0091] The preparation method of the high-strength self-healing resin-based composite material of this embodiment comprises the following steps:

[0092] Step 1, weighing 50 parts of bisphenol A type liquid epoxy resin E-54, 10 parts of tetrafunctional liquid epoxy resin AG-80, 40 parts of solid epoxy resin JF-45, and 6 parts of reactive polyurethane modified epoxy resin according to mass parts, stirring and mixing at 90° C. to obtain a base resin;

[0093] Step 2, weigh 50 parts of a curing agent (molecular structure is the same as in Example 1) according to the mass fraction, mix it evenly with the above-mentioned base resin at 40° C., and pass it through a three-roll mill three times to obtain a curable epoxy resin base;

[0094] Step 3: Prepare a film of the healable epoxy resin matrix, and then laminate the T800 unidirectional carbon fiber and the film to prepare a carbon fiber unidirectional prepreg. The mass content of the healable epoxy resin matrix in the prepreg is controlled at 40%, and the prepreg fiber surface density is 135g / m 2 , coating temperature is 80℃, laminating temperature is 90℃;

[0095] Step 4: Weigh 4 parts of high thermal conductivity graphene nanosheets (thickness 1nm, diameter 1-2μm) and ultrasonically disperse them in 100 parts of acetone solvent to prepare a uniform 4wt% graphene acetone solution. Spray the graphene solution evenly on one side of the carbon fiber prepreg, 1m2 The prepreg spraying amount is 45 ml, the proportion of graphene in the healable epoxy resin matrix is ​​2 wt %, and after being fully dried, a modified prepreg is prepared;

[0096] Step 5: Cut the prepreg into the required shape, lay it in the mold, and use the curing process of 90℃ / 0.5h+160℃ / 2h and the curing pressure of 2.0MPa. After cooling to room temperature, demould to obtain a high-strength self-healing resin-based composite material. The basic mechanical properties and thermal properties of the composite material were tested, and the results are shown in Table 2.

[0097] The healing methods of high-strength self-healing resin-based composite materials include:

[0098] Step 1: Perform a bending fatigue test on the composite material according to standard HB7624 until the composite material fails to form a delamination structure;

[0099] Step 2: Use CT to locate the specific location and size of the composite material damage, and weld metal copper sheets to lead out metal wires at both ends of the damaged part and connect them to an external power supply;

[0100] Step 3: Place the damaged composite material sample in a vacuum bag, seal it with sealing tape, and lead the power wire out of the sealing tape; evacuate the vacuum pressure to 0.096MPa, apply a voltage of 60V, detect the surface temperature at about 190°C, and let it stand for repair for 30 minutes; turn off the vacuum and voltage, remove the vacuum bag, and obtain the repaired composite material product.

[0101] The flexural strength of the repaired composite material was tested, and the repair efficiency (repaired flexural strength / original flexural strength) was calculated. The results are shown in Table 2.

[0102] Table 2 Performance data of the composite material of Example 2

[0103]

[0104] Example 3

[0105] This embodiment provides a high-strength self-healing resin-based composite material and a preparation and healing method thereof.

[0106] The preparation method of the high-strength self-healing resin-based composite material of this embodiment comprises the following steps:

[0107] Step 1, weighing 60 parts of bisphenol A type liquid epoxy resin E51, 40 parts of solid epoxy resin E20, and 5 parts of reactive polyurethane modified epoxy resin according to their mass parts, stirring and mixing at 100° C. to obtain a base resin;

[0108] Step 2: Weigh 36 parts of curing agent according to the mass fraction, mix it evenly with the above-mentioned base resin at 30°C, and pass it through a three-roll grinder three times to obtain a curable epoxy resin base. The molecular structure of the curing agent is as follows:

[0109]

[0110] Step 3: Make the epoxy resin matrix into a film, and then laminate the T800 unidirectional carbon fiber and the film to prepare a carbon fiber unidirectional prepreg. The mass content of the curable epoxy resin matrix in the prepreg is controlled at 40%, and the prepreg fiber surface density is 135g / m 2 , coating temperature is 70℃, laminating temperature is 80℃;

[0111] Step 4: Weigh 2 parts of carbon nanotubes (length 50-100 μm, diameter 10-20 nm) and 1 part of high thermal conductivity graphene nanosheets (thickness 1 nm, diameter 1-2 μm) and ultrasonically disperse them in 100 parts of acetone solvent to prepare a uniform 3 wt% carbon nanomaterial acetone solution. Spray the carbon nanomaterial solution evenly on one side of the carbon fiber prepreg, 1 m 2 The spraying amount of the prepreg is 60 ml, the proportion of the carbon nanomaterial in the resin is 2 wt %, and after being fully dried, a modified prepreg is prepared;

[0112] Step 5: Cut the modified prepreg into the required shape, lay it in the mold, and use the curing process of 100℃ / 0.5h+160℃ / 3h and the curing pressure of 2MPa. After cooling to room temperature, demould to obtain a high-strength self-healing resin-based composite material. The basic mechanical properties and thermal properties of the composite material were tested, and the results are shown in Table 3.

[0113] The healing methods of high-strength self-healing resin-based composite materials include:

[0114] Step 1: Perform a bending fatigue test on the composite material according to standard HB7624 until the composite material fails to form a delamination structure;

[0115] Step 2: locate the specific location and size of the composite material damage by ultrasonic C scanning, lead out metal wires at both ends of the damaged part by welding metal copper sheets, and connect them to an external power supply;

[0116] Step 3: Place the damaged composite material sample in a vacuum bag, seal it with sealing tape, and lead the power wire out of the sealing tape; evacuate the vacuum pressure to 0.098MPa, apply a voltage of 90V, detect the surface temperature at about 200°C, and let it stand for repair for 40 minutes; turn off the vacuum and voltage, remove the vacuum bag, and obtain the repaired composite material product.

[0117] The flexural strength of the repaired composite material was tested, and the repair efficiency (repaired flexural strength / original flexural strength) was calculated. The results are shown in Table 3.

[0118] Table 3 Performance data of the composite material of Example 3

[0119]

[0120] The inventor has conducted a large number of experimental studies during the research process, and now uses some solutions with poor performance as comparative examples.

[0121] Comparative Example 1

[0122] This comparative example provides a resin-based composite material, and the preparation method of the resin-based composite material comprises the following steps:

[0123] Step 1, weigh 50 parts of bisphenol A type liquid epoxy resin E51, 50 parts of solid epoxy resin E20, and 5 parts of reactive polyurethane modified epoxy resin according to their mass parts, and stir and mix them evenly at 100° C.;

[0124] Step 2, weighing 22 parts of curing agent 4,4′-diaminodiphenyl sulfone (DDS) and 1 part of accelerator boron trifluoride monoethylamine according to mass fraction, mixing them evenly with the above-mentioned base resin at a suitable temperature, and passing through a three-roll mill three times to obtain a mixed resin base;

[0125] Step 3: Make the epoxy resin matrix into a film, and then laminate the T700 unidirectional carbon fiber with the film to prepare a carbon fiber unidirectional prepreg. The prepreg resin mass content is controlled at 40%, and the prepreg fiber surface density is 135g / m 2 , coating temperature is 70℃, laminating temperature is 90℃;

[0126] Step 4: Weigh 3 parts of carbon nanotubes (length 50-100 μm, diameter 10-20 nm) and ultrasonically disperse them in 100 parts of ethanol solvent to prepare a uniform 3 wt% carbon nanotube ethanol solution. Spray the carbon nanotube solution evenly on one side of the carbon fiber prepreg. 2 The prepreg spraying amount is 60 ml, the proportion of carbon nanotubes in the resin is 2 wt %, and after being fully dried, a modified prepreg is prepared;

[0127] Step 5: Cut the prepreg into the required shape and lay it in the mold. The curing process is 110℃ / 0.5h+150℃ / 2h+180℃ / 1h, and the curing pressure is 2MPa. After cooling to room temperature, demould, and test the basic mechanical properties and thermal properties of the composite material. The results are shown in Table 4.

[0128] The conditions of the composite material repair method are the same as those in Example 3. The flexural strength of the repaired composite material is tested, and the repair efficiency (flexural strength after repair / original flexural strength) is calculated. The results are shown in Table 4.

[0129] Table 4 Performance data of the composite material of Comparative Example 1

[0130]

[0131]

[0132] Comparative Example 2

[0133] This comparative example provides a resin-based composite material, and the preparation method of the resin-based composite material comprises the following steps:

[0134] Step 1: Weigh 40 parts of bisphenol A liquid epoxy resin E54, 10 parts of tetrafunctional liquid epoxy resin AG-80, 50 parts of solid epoxy resin JF-45, and 6 parts of toughening agent according to mass parts, and stir and mix them evenly at 90° C.;

[0135] Step 2: Weigh 11 parts of curing agent dicyandiamide and 1 part of accelerator dichlorophenyl dimethyl urea according to mass fraction, mix them evenly with the above-mentioned base resin at a suitable temperature, and pass through a three-roll mill three times to obtain a mixed resin base;

[0136] Step 3: Prepare the epoxy resin matrix into a film, and then laminate the T800 unidirectional carbon fiber and the film to prepare a carbon fiber unidirectional prepreg. The prepreg resin mass content is controlled at 40%, the coating temperature is 80°C, and the laminating temperature is 90°C;

[0137] Step 4: Weigh 4 parts of high thermal conductivity graphene (thickness 1nm, diameter 1-2μm) and ultrasonically disperse them in 100 parts of acetone solvent to prepare a uniform 4wt% graphene acetone solution. Spray the graphene solution evenly on one side of the carbon fiber prepreg, 1m 2 The spraying amount of the prepreg is 45 ml, the proportion of graphene in the resin is 2 wt %, and after being fully dried, a modified prepreg is prepared;

[0138] Step 5: Cut the prepreg into the required shape, lay it in the mold, and use the curing process of 90℃ / 0.5h+130℃ / 2h and the curing pressure of 2.0MPa. After cooling to room temperature, demould, and test the basic mechanical properties and thermal properties of the composite material. The results are shown in Table 5.

[0139] The conditions of the composite material repair method are the same as those in Example 1. The flexural strength of the repaired composite material is tested, and the repair efficiency (flexural strength after repair / original flexural strength) is calculated. The results are shown in Table 5.

[0140] Table 5 Performance data of the composite material of Comparative Example 2

[0141]

[0142] Comparative Example 3

[0143] This comparative example provides a resin-based composite material, and the preparation method of the resin-based composite material comprises the following steps:

[0144] Step 1, weighing 60 parts of bisphenol A type liquid epoxy resin E51, 40 parts of solid epoxy resin E20, and 5 parts of reactive polyurethane modified epoxy resin according to their mass parts, stirring and mixing at 100° C. to obtain a base resin;

[0145] Step 2: Weigh 36 parts of curing agent according to the mass fraction, mix it evenly with the above-mentioned base resin at 30°C, and pass it through a three-roll grinder three times to obtain a curable epoxy resin base. The structural formula of the curing agent is as follows:

[0146]

[0147] Step 3: Prepare a film of the healable epoxy resin matrix, and then laminate the T700 unidirectional carbon fiber and the film to prepare a carbon fiber unidirectional prepreg. The mass content of the healable epoxy resin matrix in the prepreg is controlled at 40%, and the prepreg fiber surface density is 135g / m 2 , coating temperature is 70℃, laminating temperature is 80℃;

[0148] Step 4: Cut the prepreg into the required shape, lay it in the mold, and use the curing process of 80℃ / 0.5h+150℃ / 2h and the curing pressure of 2MPa. After cooling to room temperature, demould, and test the basic mechanical properties and thermal properties of the composite material. The results are shown in Table 6.

[0149] The conditions of the composite material repair method are the same as those in Example 1. The flexural strength of the repaired composite material is tested, and the repair efficiency (flexural strength after repair / original flexural strength) is calculated. The results are shown in Table 6.

[0150] Table 6 Performance data of the composite material of Comparative Example 3

[0151]

[0152] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength self-healing resin-based composite material, It is characterized in that The steps include: Step 1, stirring and mixing liquid epoxy resin, solid epoxy resin, and reactive polyurethane modified epoxy resin at 90-110° C. to obtain a matrix resin; Step 2, the curing agent and the matrix resin are mixed evenly, and passed through a three-roll grinder for multiple times to obtain a curable epoxy resin matrix; Step 3, making a healing epoxy resin matrix into a film, and then laminating the reinforced carbon fiber and the film to prepare a carbon fiber prepreg; Step 4, ultrasonically dispersing the high thermal conductivity carbon nanomaterial in a solvent to prepare a carbon nanomaterial solution, spraying the carbon nanomaterial solution evenly on one side of the carbon fiber prepreg, and fully drying it to prepare a modified prepreg; Step 5: Cut the modified prepreg, lay it in layers in a mold, and pressurize and cure it to obtain a high-strength self-healing resin-based composite material.

2. The method for preparing the high-strength self-healing resin-based composite material according to claim 1, It is characterized in that In step 1, the liquid epoxy resin is one or more of E44, E51, E54, F-44, F-51, TDE-85, and AG-80.

3. The method for preparing the high-strength self-healing resin-based composite material according to claim 1, It is characterized in that In the step 1, the solid epoxy resin is one or more of E12, E20, E-21, JF-43, and JF-45.

4. The method for preparing the high-strength self-healing resin-based composite material according to claim 1, It is characterized in that In the step 1, the mass ratio of the liquid epoxy resin, the solid epoxy resin and the reactive polyurethane modified epoxy resin is 40-80:20-60:5-10.

5. The method for preparing the high-strength self-healing resin-based composite material according to claim 1, It is characterized in that In the step 2, the curing agent is a diborane heterocyclic dianiline containing a dynamic borate ester bond bridge.

6. The method for preparing the high-strength self-healing resin-based composite material according to claim 1, It is characterized in that In the step 2, the mass ratio of the liquid epoxy resin to the curing agent is controlled to be 40-80:20-50.

7. The method for preparing the high-strength self-healing resin-based composite material according to claim 1, It is characterized in that In the step 3, the content of the healable epoxy resin matrix in the carbon fiber prepreg is controlled to be 38% to 42%.

8. The method for preparing the high-strength self-healing resin-based composite material according to claim 1, It is characterized in that In step 5, the curing process is: keep warm at 70-90°C for 0.5-1h, close the mold and pressurize, the curing pressure is 2-4MPa, heat to 140-160°C, and react for 2-3h.

9. A high-strength self-healing resin-based composite material, It is characterized in that The high-strength self-healing resin-based composite material is prepared by the preparation method according to any one of claims 1 to 8.

10. A method for healing a high-strength self-healing resin-based composite material, It is characterized in that The steps include: S1. Locate the specific location and size of composite material damage by CT or ultrasonic C-scan; S2. Lead out metal wires from both ends of the damaged part by welding metal copper sheets and connect them to an external power source; S3. Place the damaged composite material product in a vacuum bag, seal it with a sealing tape, and lead the power wire out from the sealing tape; S4, evacuate the chamber and apply external voltage to the composite material, repair the damaged part under vacuum pressure and resistance heat, turn off the vacuum and voltage, remove the vacuum bag, and obtain a repaired composite material product.

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