Shape memory based self-healing carbon fiber composites

Abstract

The present application belongs to the field of carbon fiber composite materials, and provides a shape memory based self-repairing carbon fiber composite material, which comprises a composite material body, the composite material body comprising a carbon fiber layer, a shape memory polymer base layer and a branch pipeline; the carbon fiber layer comprises first carbon fiber bundles and second carbon fiber bundles, the first carbon fiber bundles and the second carbon fiber bundles are woven into warp and weft lines, the first carbon fiber bundles and the second carbon fiber bundles are staggered to form a micro-embedded structure, and the shape memory polymer base layer is embedded in the micro-embedded structure after being formed; the branch pipeline comprises a hub part and an extension part, and the branch pipeline is arranged in a net-like structure in the composite material body; the shape memory polymer base layer and the carbon fiber layer are arranged, so that stress can be more effectively transmitted when the material is stressed, the overall strength of the composite material is enhanced, a self-repairing system is formed by the shape memory effect and the branch pipeline to realize self-repairing, the mechanical properties and functions are restored, and the service life is prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of carbon fiber composite materials, and particularly relates to a shape memory-based self-repairing carbon fiber composite material. BACKGROUND

[0002] With the continuous progress of modern science and technology, its development is increasingly stable and rapid. In this process, carbon fiber composite materials have stood out in many fields due to their outstanding mechanical properties, showing remarkable application value; in the field of aerospace, carbon fiber composite materials are widely used in the manufacture of structural parts of aircraft. Its light and strong characteristics greatly reduce the overall weight of the aircraft, thereby significantly improving flight efficiency; this not only means that the aircraft can fly more efficiently in the blue sky, but also saves a large amount of fuel cost for the airline and reduces environmental pollution; in the automotive field, carbon fiber composite materials also shine. It is actively applied to the manufacture of vehicle bodies and parts, greatly reducing the overall weight of the vehicle, making the car more lightweight. The direct benefit of this change is a significant improvement in fuel economy, reducing energy consumption, and also bringing a qualitative leap in the handling and acceleration performance of the car.

[0003] However, in the long-term practical application process, although the traditional carbon fiber composite material has many advantages, it has gradually exposed a series of problems that cannot be ignored.

[0004] The traditional carbon fiber composite material is relatively simple in structural design, usually composed of carbon fibers and resin matrix, and the most prominent disadvantage is its irreversible damage. Once the carbon fiber composite material is damaged by external impact, fatigue load or environmental erosion during use, such as microcracks, fiber breakage or delamination, the damage is often difficult to detect and repair, and due to the lack of effective self-repairing mechanism, these small damages will gradually accumulate and expand, thereby seriously affecting the overall performance and service life of the material.

[0005] Therefore, the technical personnel in the art propose a shape memory-based self-repairing carbon fiber composite material to solve the problems raised in the background art. SUMMARY

[0006] In order to solve the above technical problems, the present application provides a shape memory-based self-repairing carbon fiber composite material to solve the problem of irreversible damage of carbon fiber composite materials in the prior art. Once the carbon fiber composite material is damaged during use, it lacks an effective self-repairing mechanism, thereby seriously affecting the overall performance and service life of the material.

[0007] A shape memory-based self-healing carbon fiber composite material includes a composite material body, which comprises a carbon fiber layer, a shape memory polymer base layer, and branch pipes.

[0008] The carbon fiber layer includes a first carbon fiber bundle and a second carbon fiber bundle, which are woven together with warp and weft threads, and the first carbon fiber bundle and the second carbon fiber bundle are interwoven to form a micro-embedded structure.

[0009] The shape memory polymer base layer is disposed between two carbon fiber layers, and the matrix material is embedded in the micro-embedded structure after the shape memory polymer base layer is formed.

[0010] The branch pipeline includes a central section and an extension section, and the branch pipeline is arranged in a mesh structure within the composite material body.

[0011] The above technical solution involves placing a shape memory polymer base layer between two carbon fiber layers. After the shape memory polymer base layer is formed, the matrix material is embedded in the microstructure, which improves the interfacial bonding force. This allows the material to transfer stress more effectively when under stress, thereby enhancing the overall strength of the composite material.

[0012] Preferably, the branch pipe is filled with a self-healing agent.

[0013] Preferably, the central part is arranged in a mesh structure below the central axis of the first carbon fiber bundle and the second carbon fiber bundle.

[0014] Preferably, the extension is formed by extending from the central part, the diameter of the tube gradually decreases between the central part and the extension, and the extension is located at the micro-embedded structure.

[0015] Through the above technical solution, the pipe diameter gradually decreases between the central part and the extension part, resulting in a smaller pipe diameter near the micro-embedded structure, thereby increasing the local concentration of the self-healing agent and improving the repair efficiency. In areas with a lower probability of damage, the pipe diameter increases, reducing stress concentration inside the material. The smaller pipe diameter limits the flow rate of the self-healing agent. When the self-healing agent flows in the pipe, due to the smaller pipe diameter, the same volume of self-healing agent will have a slower flow rate when passing through the smaller pipe diameter area, which makes the self-healing agent stay in the area for a relatively longer time. This helps to concentrate the self-healing agent near the high-incidence area of ​​damage and reduce its diffusion to other non-critical areas, thereby increasing the local concentration.

[0016] Preferably, the shape memory polymer base layer is made of polyurethane and is formed by hot pressing. The carbon fiber layer and the shape memory polymer base layer in a molten state are hot pressed under high temperature and high pressure, and the shape memory polymer base layer material flows into the micro-embedded structure to form mechanical interlocking.

[0017] Preferably, the shape memory polymer base layer is made of polyester material.

[0018] Preferably, the portion of the shape memory polymer base layer near the carbon fiber layer is a hardened zone, while the interior of the shape memory polymer base layer is a soft zone.

[0019] Preferably, the central portion is located in the soft zone, and the extension portion is located in the hardened zone.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention improves the interfacial bonding force by placing a shape memory polymer base layer between two carbon fiber layers and embedding the matrix material into the micro-embedded structure after the shape memory polymer base layer is formed. This allows for more effective stress transfer when the material is under stress, thereby enhancing the overall strength of the composite material.

[0022] 2. This invention divides the shape memory polymer base layer into a hardened zone and a soft zone. The area near the carbon fiber layer has higher hardness and strength, gradually transitioning to a softer area with better shape recovery performance towards the inside. While ensuring good bonding with carbon fiber, it provides sufficient driving force for shape recovery. The shape memory polymer base layer can generate deformation and recovery force more quickly, promoting the self-healing process.

[0023] 3. By setting up branch pipes and filling the branch pipes with a self-healing agent, the material can achieve self-repair through the shape memory effect and the self-healing system formed by the branch pipes after being damaged, thereby restoring its mechanical properties and functions and extending its service life. In addition, the material has good shape memory characteristics and can restore its original shape under specific conditions, adapting to complex usage environments and working requirements.

[0024] 4. This invention designs the branch pipelines with a gradient structure, with a smaller pipe diameter near the micro-embedded structure to increase the local concentration of the self-healing agent and improve repair efficiency; while in areas with a lower probability of damage, the pipe diameter increases to reduce stress concentration inside the material; the smaller pipe diameter limits the flow rate of the self-healing agent. When the self-healing agent flows in the pipeline, due to the smaller pipe diameter, the same volume of self-healing agent will flow at a slower speed when passing through the smaller diameter area, which makes the self-healing agent stay in the area for a relatively longer time. This helps to concentrate the self-healing agent near the high-incidence area of ​​damage and reduce its diffusion to other non-critical areas, thereby increasing the local concentration. Attached Figure Description

[0025] Figure 1 This is a front view of the present invention.

[0026] Figure 2 This is an enlarged schematic diagram of the microembedded structure;

[0027] Figure 3 This is a cross-sectional structural diagram of the present invention;

[0028] Figure 4 for Figure 3 Enlarged view of part A in the middle;

[0029] Figure 5 This is a schematic diagram of the branch pipeline structure;

[0030] Figure 6 This is a schematic diagram of the structure of a shape memory polymer base layer.

[0031] In the picture:

[0032] 1. Composite material body; 2. Carbon fiber layer; 201. First carbon fiber bundle; 202. Second carbon fiber bundle; 3. Micro-embedded structure; 4. Shape memory polymer base layer; 401. Hardened area; 402. Soft area; 5. Branch pipeline; 501. Central part; 502. Extension part. Detailed Implementation

[0033] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0034] Example 1: As shown in the attached document Figure 1 To be continued Figure 6 As shown: The present invention provides a self-healing carbon fiber composite material based on shape memory, including a composite material body 1, which includes a carbon fiber layer 2, a shape memory polymer base layer 4, and branch pipes 5.

[0035] The carbon fiber layer 2 includes a first carbon fiber bundle 201 and a second carbon fiber bundle 202. The first carbon fiber bundle 201 and the second carbon fiber bundle 202 are woven together with warp and weft threads, and the first carbon fiber bundle 201 and the second carbon fiber bundle 202 are interwoven to form a micro-embedded structure 3. The carbon fiber layer 2 adopts a multi-layer interwoven carbon fiber weaving structure, which can increase the contact area between the carbon fiber and the shape memory polymer base layer 4 and improve the interfacial bonding strength. The first carbon fiber bundle 201 and the second carbon fiber bundle 202 are interwoven at different angles to form the carbon fiber layer 2, with angles of 0° / 45° / 90°.

[0036] The shape memory polymer base layer 4 is disposed between two carbon fiber layers 2, and the matrix material is embedded in the micro-embedded structure 3 after the shape memory polymer base layer 4 is formed.

[0037] The branch pipe 5 includes a central part 501 and an extension part 502. The branch pipe 5 is arranged in a mesh structure inside the composite material body 1. The branch pipe 5 is filled with a self-healing agent, which is selected from polyurethane prepolymer and catalyst or two-component epoxy resin.

[0038] The central part 501 is arranged in a mesh structure below the central axis of the first carbon fiber bundle 201 and the second carbon fiber bundle 202. The extension part 502 is formed by extending from the central part 501 and is located at the micro-embedded structure 3. The pipe diameter between the central part 501 and the extension part 502 gradually decreases. The pipe diameter of the branch pipe 5 is designed as a gradient structure. The pipe diameter is smaller near the micro-embedded structure 3 to increase the local concentration of the self-healing agent and improve the repair efficiency. In areas where the possibility of damage is low, the pipe diameter is increased to reduce stress concentration inside the material.

[0039] Smaller pipe diameters limit the flow rate of self-healing agents. When the self-healing agent flows in the pipe, the flow rate of the same volume of self-healing agent will be slower when passing through the smaller pipe diameter area due to the smaller pipe diameter. This makes the self-healing agent stay in the area for a relatively longer time, which helps to concentrate the self-healing agent near the high-incidence area of ​​damage and reduce its diffusion to other non-critical areas, thereby increasing the local concentration.

[0040] The shape memory polymer base layer 4 is made of polyurethane or polyester and is formed by hot pressing. The carbon fiber layer 2 and the shape memory polymer base layer 4 in the molten state are hot pressed under high temperature and high pressure. The shape memory polymer base layer 4 material flows into the micro-embedded structure 3 to form mechanical interlocking.

[0041] The shape memory polymer base layer 4 can also be impregnated by a process in which the carbon fiber layer 2 with micro-embedded structure 3 is impregnated in the liquid shape memory polymer base layer 4 material, and then the matrix material is fully inserted into the micro-embedded structure 3 by vacuuming or applying pressure to complete the mechanical integration.

[0042] The shape memory polymer base layer 4 can also introduce polymerizable shape memory polymer monomers or prepolymers on the surface of the carbon fiber layer 2, and then generate the shape memory polymer base layer 4 in situ on the carbon fiber surface by initiating a polymerization reaction, and interlock with the micro-embedded structure 3.

[0043] The portion of the shape memory polymer base layer 4 near the carbon fiber layer 2 is the hardened area 401, while the center of the shape memory polymer base layer 4 is the soft area 402. The central part 501 is located in the soft area 402, and the extension part 502 is located in the hardened area 401. The shape memory polymer base layer 4 has higher hardness and strength in the area near the carbon fiber layer 2, and gradually transitions to a softer area with better shape recovery performance towards the interior. This can provide sufficient shape recovery driving force while ensuring good bonding with carbon fiber. The shape memory polymer base layer 4 can generate deformation and recovery force more quickly, promoting the self-healing process.

[0044] As can be seen from the above, the first carbon fiber bundle 201 and the second carbon fiber bundle 202 are woven with warp and weft threads, providing a foundation for high strength and high modulus. The interlaced micro-embedded structure 3 increases the contact area and mechanical interlocking effect with the shape memory polymer base layer 4, improves the interfacial bonding force, and thus can more effectively transfer stress when subjected to force, thereby enhancing the overall strength of the composite material.

[0045] The branch pipes 5 are distributed in a mesh pattern within the composite material. The central part 501 is located in the soft area 402 of the shape memory polymer base layer 4, which facilitates the storage and flow of the self-healing agent. The extension part 502 is located in the hardened area 401, which can more accurately guide the self-healing agent to the damaged area. When the material is damaged, the pressure change in the branch pipes 5 causes the self-healing agent to flow to the damaged area, and the repair is achieved through chemical reaction and physical action.

[0046] After being damaged, this composite material can self-repair through the shape memory effect and the self-healing system formed by the branch pipes 5, restoring its mechanical properties and functions and extending its service life. Furthermore, the material possesses excellent shape memory characteristics, enabling it to recover its original shape under specific conditions, adapting to complex operating environments and requirements. Combined with the reinforcement of carbon fiber, this results in a composite material with high strength, high modulus, and good toughness, meeting the mechanical performance requirements of various application scenarios.

[0047] Example 2: Carbon fiber layer treatment: T700 carbon fiber was selected and woven into a fabric using a 0° / 90° interlacing method. The carbon fiber fabric was subjected to plasma treatment at 60W for 10 minutes under an argon atmosphere. Then, it was immersed in a 3% silane coupling agent solution and stirred at 50°C for 40 minutes. After removal, it was dried in an oven at 80°C for 2 hours.

[0048] Shape memory polymer (SMP) matrix preparation: Select polyester-type SMP and heat it to 150°C to melt it.

[0049] Branching duct 5 structure construction: 3D printing was used to print a branching vascular network using a biocompatible flexible material. The diameter of the tubes gradually increases from the center to the edge, with a minimum diameter of 0.1 mm and a maximum diameter of 0.5 mm.

[0050] Composite material molding: The treated carbon fiber cloth is placed in a mold, molten SMP is poured in, and the mixture is held at 8 MPa pressure for 1.5 hours to allow the SMP to fully impregnate the carbon fiber cloth. Then, a structure with a vascular network is embedded in it, and pressure is applied again to make it tightly bonded. The mixture is then allowed to cool naturally to room temperature.

[0051] The test data are as follows: Tensile strength: 800 MPa;

[0052] Shape recovery time (from deformation to 90% recovery): 8 minutes (at 80°C);

[0053] Self-repair efficiency (ratio of the strength restored after damage to the original strength): 75%.

[0054] Example 3: Carbon fiber layer treatment: T800 carbon fiber was used for asymmetric weaving. The carbon fiber woven fabric was subjected to high-temperature treatment in a nitrogen atmosphere at 400°C for 1.5 hours. Subsequently, it was immersed in an 8% sodium hydroxide solution and treated at room temperature for 30 minutes. After removal, it was washed and dried at 100°C for 3 hours.

[0055] Shape memory polymer (SMP) matrix preparation: Polyurethane-type SMP is selected and synthesized through chemical reaction, controlling the molecular weight and degree of crosslinking.

[0056] Branch tubing 5 structure construction: A vascular network was prepared using microfluidic technology, with a diameter ranging from 0.05 mm to 0.4 mm and exhibiting a gradual distribution.

[0057] Composite material molding: Carbon fiber cloth is laid at the bottom of the mold, some SMP liquid is poured in, then the vascular network is placed, and the remaining SMP liquid is poured in. Air bubbles are removed under vacuum, and the mixture is heated to 120℃ for 2 hours to cure.

[0058] The test data is as follows:

[0059] Tensile strength: 950 MPa;

[0060] Shape recovery time (from deformation to 90% recovery): 7 minutes (at 70°C);

[0061] Self-repair efficiency (ratio of the strength restored after damage to the original strength): 78%.

[0062] Example 4: Carbon fiber layer treatment: T300 carbon fiber was selected and woven into a plain weave fabric. The carbon fiber fabric was subjected to electrochemical oxidation treatment in a sulfuric acid solution with a current density of 1 A / dm³. 2 Process for 20 minutes. Then rinse with deionized water and dry at 60°C for 2 hours.

[0063] Shape memory polymer (SMP) matrix preparation: prepared in a twin-screw extruder using a polyesteramide type SMP.

[0064] Branch pipe 5 structure construction: The vascular network mold is made on a flexible substrate using photolithography, and then filled with a soft polymer. The pipe diameter varies between 0.08mm and 0.35mm.

[0065] Composite material molding: The treated carbon fiber cloth is composited with the SMP matrix through a hot pressing process at a temperature of 180℃, a pressure of 12MPa, and a time of 1 hour; then the vascular network is embedded and pressure is applied to bond them together.

[0066] The test data is as follows:

[0067] Tensile strength: 750 MPa;

[0068] Shape recovery time (from deformation to 90% recovery): 9 minutes (at 90°C);

[0069] Self-repair efficiency (ratio of restored strength to original strength after damage): 70%.

[0070] Example 5: Carbon fiber layer treatment: Using T1000 carbon fiber, woven in a twill pattern, the carbon fiber cloth was treated in oxygen plasma for 8 minutes at a power of 70W, then soaked in a 5% titanate coupling agent solution for 30 minutes, and dried at 70°C for 2.5 hours.

[0071] Shape memory polymer (SMP) matrix preparation: Synthesize polyether-type SMP and control its glass transition temperature.

[0072] Branch pipeline 5 structure construction: The vascular network was prepared using electrospinning technology, with the diameter gradually changing from 0.06 mm to 0.45 mm.

[0073] Composite material molding: Carbon fiber cloth and SMP matrix are combined by winding process, cured at 10MPa pressure and 160℃ for 3 hours, and then embedded into vascular network.

[0074] The test data is as follows:

[0075] Tensile strength: 1000MPa

[0076] Shape recovery time (from deformation to 90% recovery): 6 minutes (at 60°C)

[0077] Self-repair efficiency (ratio of the strength restored after damage to the original strength): 80%.

[0078] Example 6: Carbon Fiber Layer Treatment: T1100 carbon fiber was selected and a satin weave was used. The carbon fiber weave was first treated in an ultraviolet environment for 15 minutes to enhance its surface activity. Subsequently, it underwent low-temperature plasma treatment in a carbon dioxide atmosphere for 12 minutes at a power of 80W. Afterward, it was immersed in a 6% aluminate coupling agent solution and stirred at 60°C for 50 minutes. It was then removed and dried in a 90°C oven for 2.5 hours. The ultraviolet and low-temperature plasma treatments further improved the surface roughness and chemical activity of the carbon fiber, increasing its bonding strength with the shape memory polymer substrate. The aluminate coupling agent treatment formed chemical bonds on the carbon fiber surface, improving interfacial compatibility and thus more effectively transferring stress under load, enhancing the overall strength of the composite material.

[0079] Shape memory polymer (SMP) matrix preparation: Polycarbonate-based SMP was selected and synthesized via solution polymerization. The polymerization conditions were strictly controlled to obtain the ideal molecular weight and crosslinking density. The SMP was heated to 180℃ to a molten state. Polycarbonate-based SMP possesses good mechanical and shape memory properties; by precisely controlling the synthesis conditions, its properties can be optimized, improving the shape recovery ability and mechanical properties of the composite material. Branching pipe structure construction: A branching vascular network was constructed using a flexible and biocompatible polymer material via laser engraving. The pipe diameter increases linearly from the center to the edge, with a minimum diameter of 0.08 mm and a maximum diameter of 0.6 mm.

[0080] Laser engraving enables the creation of high-precision vascular networks. The rational design of the tube diameter can better control the flow and distribution of the self-healing agent, ensuring that the self-healing agent can quickly and accurately reach the damaged site when damage occurs, thereby improving repair efficiency.

[0081] Composite material molding: The treated carbon fiber cloth is placed in a mold, molten SMP is poured in, and the mixture is kept under a pressure of 10 MPa for 2 hours to allow the SMP to fully impregnate the carbon fiber cloth. Then, the structure with the vascular network is embedded in it, and a pressure of 15 MPa is applied again to make it tightly bonded. It is then allowed to cool naturally to room temperature.

[0082] Higher pressure and longer time help SMP fully penetrate into the carbon fiber layers, forming a good interfacial bond and improving the integrity and mechanical properties of the composite material. Double pressurization ensures a tight bond between the vascular network and the composite material, preventing separation or leakage during use.

[0083] The test data are as follows: Tensile strength: 1100 MPa;

[0084] Shape recovery time (from deformation to 90% recovery): 5 minutes (at 70°C); Self-healing efficiency (ratio of recovered strength to original strength after damage): 85%.

[0085] The above experiments verify that this material has high tensile strength, indicating its excellent load-bearing capacity; the short shape recovery time demonstrates its rapid response and shape recovery ability; and the high self-healing efficiency means that the composite material can effectively restore its mechanical properties after damage, extend its service life, and adapt to various complex working environments and application scenarios.

[0086] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0087] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-healing carbon fiber composite material based on shape memory, characterized in that, It includes a composite material body (1), which includes a carbon fiber layer (2), a shape memory polymer base layer (4), and branch pipes (5); The carbon fiber layer (2) includes a first carbon fiber bundle (201) and a second carbon fiber bundle (202). The first carbon fiber bundle (201) and the second carbon fiber bundle (202) are woven together with warp and weft threads, and the first carbon fiber bundle (201) and the second carbon fiber bundle (202) are interwoven to form a micro-embedded structure (3). The shape memory polymer base layer (4) is disposed between two carbon fiber layers (2), and the matrix material is embedded in the micro-embedded structure (3) after the shape memory polymer base layer (4) is formed; the part of the shape memory polymer base layer (4) near the carbon fiber layer (2) is the hardened area (401), and the interior of the center of the shape memory polymer base layer (4) is the soft area (402); The branch pipe (5) includes a central part (501) and an extension part (502). The branch pipe (5) is arranged in a mesh structure inside the composite material body (1). The branch pipe (5) is filled with a self-healing agent. The extension part (502) is formed by extending from the central part (501). The pipe diameter between the central part (501) and the extension part (502) decreases step by step, and the extension part (502) is located at the micro-embedded structure (3). The central portion (501) is located in the soft area (402), and the extension portion (502) is located in the hardened area (401).

2. The self-healing carbon fiber composite material based on shape memory as described in claim 1, characterized in that: The shape memory polymer base layer (4) is made of polyurethane and is formed by hot pressing. The carbon fiber layer (2) and the shape memory polymer base layer (4) in the molten state are hot pressed under high temperature and high pressure. The shape memory polymer base layer (4) material flows into the micro-embedded structure (3) to form mechanical interlocking.

3. The self-healing carbon fiber composite material based on shape memory as described in claim 1, characterized in that: The shape memory polymer base layer (4) is made of polyester.

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