A toughened composite material with an aramid interlayer reinforced by carbon nanotubes and its preparation method

Abstract

This invention relates to the field of composite materials technology, providing a toughened aramid fiber interlayer composite material with added carbon nanotubes and its preparation method. First, an aramid fiber interlayer preform is prepared using a wet web-forming process. The fiber surface is activated by hydrofluoric acid etching, and soluble polyetheretherketone (PEEK) resin with active end groups is grafted onto the aramid fiber surface, followed by thorough impregnation with carbon nanotubes to obtain the carbon nanotube-added aramid fiber interlayer. The crystallinity of PEEK is restored through an acid-reduction reaction. A continuous carbon fiber reinforced PEEK prepreg tape is then combined with the prepared toughened interlayer according to a layup design, and the composite board is obtained by hot pressing. This invention significantly improves the mechanical properties of continuous carbon fiber reinforced PEEK composite materials, especially the interlaminar type II fracture toughness, effectively enhancing its anti-delamination ability. It provides an innovative solution for interlaminar toughening of this type of composite material and has broad application prospects in aerospace, new energy, and artificial intelligence fields.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, and particularly relates to a toughened composite material with an aramid interlayer reinforced by adding carbon nanotubes and its preparation method. Background Technology

[0002] Fiber-reinforced resin matrix composites are a class of advanced materials with fibers as reinforcements and resin as the matrix. They have advantages such as high specific strength and specific modulus, fatigue resistance, corrosion resistance and strong designability. They are widely used in aerospace, rail transportation, new energy and other fields, showing broad development prospects.

[0003] Continuous carbon fiber reinforced polyetheretherketone prepreg (CF / PEEK) is a typical example. In practical applications, when the stress state is uncertain or isotropic properties are required, unidirectional layup is often used for structural design. However, the interlaminar transfer of load and energy in this type of composite material mainly relies on resin, resulting in weak mechanical properties in the thickness direction. Under external loads, the laminate is prone to failure from resin-rich areas, causing delamination damage. Once delamination occurs, the reinforcing effect of the fibers cannot be fully utilized, seriously affecting the overall performance and service life of the material, thus limiting its further application. Therefore, improving the comprehensive performance of CF / PEEK, especially interlaminar properties and anti-delamination ability, while ensuring processability has become a key research direction.

[0004] Currently, methods to improve the interlaminar fracture toughness of composite materials mainly include film toughening, particle toughening, and fiber toughening. Fiber toughening effectively improves interlaminar toughness by introducing thermoplastic nonwoven fabrics or chopped fiber films into the interlaminar layer, but its effectiveness is affected by factors such as fiber type, areal density, composition, and compatibility with the resin matrix. Among various fibers, chopped aramid fibers exhibit excellent toughening capabilities. Their toughening mechanisms include not only fiber debonding, pull-out, and transverse fracture, but also a unique longitudinal tearing mode, resulting in a significantly better toughening effect than other short fibers such as carbon fiber and glass fiber. However, existing research mainly focuses on the interlaminar reinforcement of carbon fiber / epoxy resin (CF / EP) systems with chopped aramid fibers, while research on CF / PEEK systems remains relatively limited. Based on this, introducing carbon nanotubes into the interlaminar layer of aramid fibers can further optimize interlaminar properties. Carbon nanotubes possess extremely high specific surface area and excellent mechanical properties, enabling them to form a denser and more robust three-dimensional network structure in the interlayer region. This effectively enhances the interfacial bonding between fibers and resin, further improving crack propagation resistance. Furthermore, the addition of carbon nanotubes helps regulate the areal density of the fiber interlayer. By optimizing their concentration, the interlaminar fracture toughness of the composite material can be synergistically enhanced without sacrificing in-plane mechanical properties. Therefore, using carbon nanotubes and chopped aramid fibers together for interlaminar toughening of CF / PEEK composites not only leverages the macroscopic toughening mechanism of aramid fibers but also utilizes the nano-reinforcing effect of carbon nanotubes to achieve multi-level, multi-scale interlaminar strengthening, providing an important pathway for expanding the application of CF / PEEK in high-end fields. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an aramid interlayer toughened composite material with added carbon nanotubes, in order to solve the problems mentioned in the background art.

[0006] The present invention is implemented as follows: a method for preparing an aramid interlayer toughened composite material with added carbon nanotubes includes the following steps:

[0007] Step 1: Cut the aramid fiber, put it into deionized water, add a compound dispersant, disperse it evenly, collect and separate the solid and liquid by vacuum suction technology, and wet web to obtain the aramid fiber intermediate layer preform.

[0008] Step 2: Place the aramid fiber interlayer preform in a dilute hydrofluoric acid solution for standing and fluorination, then wash and vacuum dry to obtain the fluorinated aramid fiber interlayer preform.

[0009] Step 3: Graft the fluorinated aramid fiber interlayer preform with soluble polyether ether ketone resin to obtain a soluble polyether ether ketone grafted aramid fiber interlayer.

[0010] Step 4: Dissolve carbon nanotubes in dichloromethane solution, add polyvinylpyrrolidone, and ultrasonically disperse to prepare a carbon nanotube-dichloromethane suspension. Impregnate the aramid fiber interlayer grafted with soluble polyether ether ketone (PEEEK). After the solvent evaporates, the aramid fiber interlayer with added carbon nanotubes is obtained. The soluble PEEKEK resin in the aramid fiber interlayer with added carbon nanotubes is reduced to crystalline PEEKEK through an acidification-reduction reaction to prepare a toughened aramid fiber interlayer with crystalline PEEKEK grafted and impregnated with carbon nanotubes. The amount of carbon nanotubes added is 0.375%wt-1.125%wt of the soluble PEEKEK grafted aramid fiber interlayer.

[0011] Step 5: Graft crystalline polyetheretherketone (PEEK) onto a carbon nanotube-impregnated aramid fiber interlayer and a continuous carbon fiber reinforced PEEK prepreg tape of T700, 0.14 mm thickness, and 305 mm width, according to [07 / AF / 04]. s The symmetrical structure is placed in the mold in the following order: 7 layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction, followed by an aramid fiber interlayer. 8 more layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction, followed by another aramid fiber interlayer. 7 more layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction. The mixture is then hot-pressed and demolded to obtain a toughened composite material with an aramid interlayer and added carbon nanotubes.

[0012] Another objective of this invention is to provide a toughened composite material with an aramid interlayer reinforced by adding carbon nanotubes, which is prepared using the above-described preparation method.

[0013] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0014] Significantly improves interlayer performance and interfacial bonding: Through fluorination treatment and soluble polyether ether ketone grafting process, the interfacial compatibility and chemical bonding between aramid fiber and PEEK resin are significantly enhanced; further introduction of carbon nanotubes forms a three-dimensional reinforcing network in the interlayer, effectively bridging cracks and synergistically improving the interlayer fracture toughness and anti-delamination ability of the composite material.

[0015] Achieving multi-scale synergistic toughening and structural stability: Aramid fibers provide macro-scale toughening mechanisms such as debonding, pull-out and longitudinal tearing, while nano-scale carbon nanotubes further consume crack propagation energy through their high specific strength, high toughness and interface effect. The combination of the two achieves macro-nano multi-scale synergistic toughening, and the stability of the overall structure of the toughened intermediate layer and CF / PEEK prepreg tape is ensured by resin crystallization after hot pressing.

[0016] Taking into account the comprehensive mechanical properties of composite materials: The toughened interlayer structure prepared in the embodiments of the present invention is reasonably designed, and the addition of carbon nanotubes is optimized in proportion. While effectively improving the interlayer properties, it does not adversely affect the in-plane mechanical properties of the composite material, thus achieving a good balance between interlayer toughness and in-plane properties.

[0017] Precise and controllable layup structure and process compatibility: Existing interlayer toughening technologies often face problems such as asymmetrical layups, complex processes, or difficulty in scaling up. The embodiments of this invention adopt [07 / AF / 04]. s A symmetrical layup was constructed using alternating layers of continuous carbon fiber / PEEK prepreg tape (rigid layer) and carbon nanotube-impregnated aramid fiber interlayer (toughness layer), creating a "07 / AF / 04" symmetrical structure. The aramid interlayer acts as a toughness isolation layer, effectively deflecting cracks and absorbing impact energy, while the symmetrical carbon fiber / PEEK layers ensure overall stiffness and strength. This achieves synergistic optimization of stiffness and toughness, overcoming the performance trade-offs common in traditional toughening technologies. [07 / AF / 04] s The symmetrical structure can effectively balance the residual stress during the hot pressing process and reduce warping deformation. At the same time, the processing is simple and easy to stack, highly compatible with existing hot pressing processes, and easy to achieve stable and repeatable manufacturing. Attached Figure Description

[0018] Figure 1 A flowchart illustrating the preparation process of an aramid interlayer toughened composite material with added carbon nanotubes, provided in an embodiment of the present invention;

[0019] Figure 2 A physical image of the aramid fiber interlayer grafted with crystalline polyether ether ketone and impregnated with carbon nanotubes provided in an embodiment of the present invention.

[0020] Figure 3 A physical image of the aramid interlayer toughened composite material with added carbon nanotubes provided in an embodiment of the present invention;

[0021] Figure 4 A cross-sectional scanning electron microscope image of the aramid interlayer toughened composite material with added carbon nanotubes provided in an embodiment of the present invention;

[0022] Figure 5 Comparison of type II interlaminar toughness stress-strain curves of composite materials provided in embodiments of the present invention;

[0023] Figure 6 Comparison of interlaminar shear strength stress-strain curves of composite materials provided in embodiments of the present invention;

[0024] Figure 7 Comparison of flexural strength stress-strain curves of composite materials provided in embodiments of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0027] Example 1: A toughened composite material with an aramid interlayer reinforced by added carbon nanotubes, the preparation process of which is as follows: Figure 1 As shown, the specific steps are as follows:

[0028] (1) 1.2g of aramid fibers cut to 5-6mm were put into a beaker containing 5L of deionized water, and compound dispersant (0.5g polyacrylamide, 1.5g sodium dodecyl sulfate, 3g polyethylene oxide) was added. The mixture was stirred at 500r / min for 120min using a mechanical stirrer (Xiniu Technology, JB80-SH) to disperse it evenly. The dispersed aramid fiber liquid was then collected and separated into solid and liquid by vacuum suction in a vacuum filtration device. The mixture was then wet-laid to obtain the aramid fiber intermediate layer preform.

[0029] (2) Place 1.2g of aramid fiber interlayer preform into 150mL of dilute hydrofluoric acid solution and let it stand (hydrofluoric acid (48-55%w / w): water = 1:2), fluorinate for 30min, then wash with deionized water 3 times, 1h each time to ensure the removal of residual hydrofluoric acid, and vacuum dry at 100℃ for 12h to obtain fluorinated aramid fiber interlayer preform;

[0030] (3) Synthesis of 1,1-bis(4-fluorophenyl)-N-phenylmethylimine, a polyether ether ketone monomer containing a ketimine structure, via Schiff base reaction: Toluene (80 mL), aniline (14 mL, 150 mmol), 4,4'-difluorobenzophenone (22.0 g, 100 mmol), and molecular sieve (4 Å, 50 g, activated at 400 °C for 4 h) were placed in a 250 mL three-necked flask, heated to reflux under nitrogen and reacted for 24 h. The molecular sieve was then removed by filtration, and the toluene in the filtrate was evaporated to dryness to obtain a reddish-brown crude product. Since the monomer requires high purity, the crude product was recrystallized three times in methanol to obtain light yellow blocky crystals with a yield of 62%.

[0031] Synthesis of 4-fluoro-4'-nitrobenzophenone via Friedel-Crafts acylation reaction of fluorobenzene and 4-nitrobenzoyl chloride: First, fluorobenzene (80 mL) was added to a 250 mL three-necked flask, followed by 4-nitrobenzoyl chloride (18.5 g, 100 mmol). The mixture was stirred until completely dissolved. Then, the three-necked flask was placed in an ice bath at 0 °C, and pre-ground anhydrous AlCl3 (17 g, 128 mmol) was slowly added (maintaining a low temperature during the addition process). After stirring at 0 °C for 2 h, the mixture was heated to reflux temperature and... The reaction was maintained for 6 hours. After the reaction was complete, the mixture was cooled to room temperature. Then, 100 mL of deionized water was slowly added to the three-necked flask, and the mixture was heated to reflux temperature. Excess fluorobenzene was removed using a Dean-Stark desiccant. After the fluorobenzene was completely removed, the reaction system was cooled to room temperature. The product was poured into cold water, and a lumpy, light yellow crude product precipitated at the bottom. The lumpy, light yellow crude product was filtered and washed three times each with sodium hydroxide solution (0.5 M) and deionized water. The crude product was dissolved in ethanol and recrystallized twice to obtain light yellow crystals of 4-fluoro-4'-nitrobenzophenone, with a yield of approximately 85%.

[0032] The reduction of 4-fluoro-4'-nitrobenzophenone to 4-fluoro-4'-aminobenzophenone using tin(II) chloride dihydrate: First, methanol (150 mL) and 4-fluoro-4'-nitrobenzophenone (0.012 mol, 2.94 g) were added to a 250 mL three-necked flask. Then, tin(II) chloride dihydrate (0.06 mol, 13.48 g) was added to the flask. After reacting at reflux for 6 h, the insoluble matter was filtered off, and the filtrate was concentrated by evaporation. The pH of the filtrate was adjusted to 9 with a saturated aqueous solution of Na2CO3 to remove excess tin salt. After filtration, the mixture was extracted twice with ethyl acetate. The organic phases were combined and dried with anhydrous sodium sulfate. After filtering off the sodium sulfate, the organic phase was subjected to a rotary evaporator to remove the solvent, yielding an orange product. The product was then dried under vacuum to obtain an amino-terminated monomer with a yield of approximately 68%.

[0033] Polymerization was carried out using 1,1-bis(4-fluorophenyl)-N-phenylmethylimine and biphenylhydrazine at a ketone:phenol ratio of 1:1.03: 1,1-bis(4-fluorophenyl)-N-phenylmethylimine (5.866 g, 20 mmol), biphenylhydrazine (4.008 g, 22 mmol), sulfolane (23.51 mL), anhydrous potassium carbonate (3.648 g, 26.4 mmol), and toluene (11.755 mL) in a 250 mL three-necked flask. The system was first heated to 120 °C and maintained for 3 h. The water generated in the reaction was removed by using toluene, and the water was separated by Dean-Stark separator. Turbidity was observed in the apparatus. The temperature was then raised to 190°C to initiate the polymerization reaction. The polymer viscosity continued to increase, and after 12 hours, a viscous, deep yellow polymer solution was formed. After polymerization, the heating power was reduced, and the system was cooled to 130°C. 4-fluoro-4'-aminobenzophenone end-capping agent (0.901 g, 3 mmol) was added, and the reaction was continued at 120°C for 4 hours. The product was discharged in methanol to obtain amino-terminated strip polymer. After pulverizing, it was washed three times each with ethanol, water, and ethanol at reflux temperature. Finally, the product was dried in a vacuum oven for 12 hours to obtain an orange-yellow powdery soluble polyether ether ketone resin.

[0034] Weigh 1.2g of soluble polyether ether ketone resin and dissolve it in 50ml of tetrahydrofuran solution. Use the solution entirely to impregnate and graft the fluorinated aramid fiber interlayer preform. Seal the system for 12h and shake appropriately. After the grafting is complete, open the system and wait for the solvent to evaporate completely at room temperature. Then, perform high-temperature hot pressing at 140℃ and 10MPa for 20min to obtain the soluble polyether ether ketone grafted aramid fiber interlayer.

[0035] (4) Weigh 0.375%wt of carbon nanotubes, specifically soluble polyether ether ketone grafted aramid fiber interlayer, and dissolve them in 100mL of dichloromethane solution. Weigh 0.02g of polyvinylpyrrolidone K30 (pvp) as a dispersant and dissolve it in dichloromethane. Stir for 10min, use ultrasonic cleaner (bath type) for ultrasonication, and after ultrasonication for 5min, place it in ice water to cool and defoam. Continue ultrasonication until the carbon nanotubes are uniformly diffused. The total ultrasonication time is 60min (5min×12 times). Then, immerse the soluble polyether ether ketone grafted aramid fiber interlayer in it. After the solvent evaporates, the aramid fiber interlayer with added carbon nanotubes is obtained.

[0036] The soluble polyetheretherketone resin in the aramid fiber interlayer with added carbon nanotubes was reduced to crystalline polyetheretherketone via an acidification-reduction reaction: A 1L capacity hydrothermal synthesis reactor liner was used, and 500mL of 1M hydrochloric acid solution was added for the acidification-reduction reaction. The aramid short fiber interlayer with added carbon nanotubes prepared above was trimmed to a suitable size so that it could be completely immersed in the hydrochloric acid solution in the reactor. The liner was placed in the hydrothermal synthesis reactor, the lid was tightened, and the reactor was heated at 150℃ for 12 hours. The reduced product was then removed, thoroughly washed with water, and vacuum dried to obtain a toughened aramid fiber interlayer grafted with crystalline polyetheretherketone and impregnated with carbon nanotubes. Figure 2 As shown, carbon nanotubes are uniformly dispersed in aramid fibers;

[0037] (5) Grafting crystalline polyetheretherketone with a carbon nanotube-impregnated aramid fiber interlayer and a continuous carbon fiber reinforced polyetheretherketone prepreg tape of T700, 0.14 mm thick, and 305 mm wide is performed according to [07 / AF / 04]. s The symmetrical structure is laid in the mold, the upper and lower pressure plates are placed, and the mold is placed in a vacuum hot press. The hot pressing program is run: the layup sequence is [0 / 0 / 0 / 0 / 0 / 0 / 0 / AF / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / AF / 0 / 0 / 0 / 0 / 0 / 0 / 0], that is, 7 layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction, one layer of aramid fiber toughening intermediate layer is added, and 8 more layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction, another layer of aramid fiber toughening intermediate layer is added, and then 7 more layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction. The hot pressing program is set as follows: heating rate 15℃ / min, holding temperature 400℃, pressure 8MPa, holding time 40 min, cooling rate 15℃ / min. After the program is completed, the mold is demolded to obtain a composite material with aramid intermediate layer toughening added with carbon nanotubes.

[0038] The obtained composite material was named CNT1@AF-CF / PEEK, such as Figure 3 As shown, the cross-section was analyzed, and the electron microscope images were obtained as follows. Figure 4 As shown, the presence of the interlayer toughening layer is clearly visible, and the aramid toughening layer has a good interfacial bond with the carbon fiber.

[0039] Example 2: Compared with Example 1, the only difference is that the amount of carbon nanotubes added in step (4) is adjusted to 0.75%wt, and the resulting composite material is named CNT2@AF-CF / PEEK.

[0040] Example 3: Compared with Example 1, the only difference is that the amount of carbon nanotubes added in step (4) is adjusted to 1.125%wt, and the resulting composite material is named CNT3@AF-CF / PEEK.

[0041] Comparative Example 1: A continuous carbon fiber reinforced polyether ether ketone-based composite material with an aramid fiber interlayer toughened by the composite material, the specific steps of which are as follows:

[0042] (1), (2), and (3) are the same as in Example 1;

[0043] (4) No carbon nanotubes are added to the aramid fiber interlayer grafted with soluble polyether ether ketone. The polyether ether ketone resin in the aramid fiber interlayer is reduced to crystalline polyether ether ketone by acidification and reduction to obtain the toughened aramid fiber interlayer grafted with the target crystalline polyether ether ketone.

[0044] (5) The intermediate layer of aramid fiber grafted with crystalline polyether ether ketone and impregnated with carbon nanotubes was replaced with an intermediate layer of aramid short fiber toughened with crystalline polyether ether ketone grafted with crystalline polyether ether ketone. The resulting composite material was named AF-CF / PEEK.

[0045] Comparative Example 2: A continuous carbon fiber reinforced polyetheretherketone (PEEK) composite material, the specific steps of which are as follows:

[0046] T700, 0.14mm thick, 305mm wide continuous carbon fiber reinforced polyetheretherketone prepreg tape was laid in 24 layers in the same direction and placed into a mold of uniform size. The upper and lower pressure plates of the mold were placed, and the mold was placed in a vacuum hot press. The hot pressing program was started, with a heating rate of 15℃ / min, a holding temperature of 400℃, a pressure of 8MPa, a holding time of 40min, and a cooling rate of 15℃ / min. After the program was completed, the mold was demolded to obtain a continuous carbon fiber reinforced polyetheretherketone composite material, which was named CF / PEEK.

[0047] Performance testing:

[0048] The mechanical properties of the composite materials prepared in Examples 1-3 and Comparative Examples 1-2 were tested: Type II interlaminar fracture toughness was determined according to ASTM D7905-2019; interlaminar shear strength was determined according to national standard GB / T30969-2014; and flexural strength was determined according to national standard GB / T1449-2005. The test results are as follows: Figures 5 to 7 And as shown in Table 1:

[0049] Table 1 Mechanical properties of composite materials

[0050]

[0051] Examples 1-3 use aramid fiber toughening interlayers grafted with crystalline polyether ether ketone and impregnated with carbon nanotubes. Through the synergistic effect of inorganic particles and fiber layers, a "hard-soft-hard" sandwich structure is formed between the composite material layers. This significantly enhances the type II interlaminar fracture toughness of the composite material while improving its mechanical properties such as flexural strength and interlaminar shear strength. The addition of carbon nanotubes increases the layer density of the aramid fiber interlayer. Simultaneously, the aramid fibers are uniformly dispersed in the slurry, and the carbon nanotubes are uniformly dispersed in the dispersion and completely and uniformly impregnated onto the aramid fibers. This makes the prepared aramid fiber... The isotropic nature of the fiber interlayer ensures uniform stress distribution in the composite material to the greatest extent. Test results show that the composite material (CNT@AF-CF / PEEK) prepared in this embodiment of the invention significantly improves interlaminar properties while maintaining flexural performance, compared with the comparative examples (AF-CF / PEEK and CF / PEEK). In particular, the type II interlaminar fracture toughness is improved by 3.7-5.6 times. The improvement in interlaminar toughness can overcome the bottleneck of interlaminar fracture in laminated composite boards during product processing, thereby improving the interlaminar properties and anti-delamination ability of the composite material.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an aramid interlayer toughened composite material with added carbon nanotubes, characterized in that, Includes the following steps: Step 1: Cut the aramid fiber, put it into deionized water, add a compound dispersant, disperse it evenly, collect and separate the solid and liquid by vacuum suction technology, and wet web to obtain the aramid fiber intermediate layer preform. Step 2: Place the aramid fiber interlayer preform in a dilute hydrofluoric acid solution for standing and fluorination, then wash and vacuum dry to obtain the fluorinated aramid fiber interlayer preform. Step 3: Graft the fluorinated aramid fiber interlayer preform with soluble polyether ether ketone resin to obtain a soluble polyether ether ketone grafted aramid fiber interlayer. Step 4: Carbon nanotubes are dissolved in dichloromethane solution, polyvinylpyrrolidone is added, and the mixture is ultrasonically dispersed to prepare a carbon nanotube-dichloromethane suspension. A soluble polyetheretherketone-grafted aramid fiber interlayer is then impregnated in this suspension. After solvent evaporation, an aramid fiber interlayer with added carbon nanotubes is obtained. The soluble polyetheretherketone resin in the carbon nanotube-added aramid fiber interlayer is reduced to crystalline polyetheretherketone through an acidification-reduction reaction, thus preparing a crystalline polyetheretherketone-grafted and carbon nanotube-impregnated aramid fiber toughened interlayer. The amount of carbon nanotubes added is 0.375%wt-1.125%wt of the soluble polyetheretherketone-grafted aramid fiber interlayer. The specific process of dissolving carbon nanotubes in dichloromethane solution, adding polyvinylpyrrolidone, and ultrasonically dispersing to prepare the carbon nanotube-dichloromethane suspension is detailed below. The process is as follows: Carbon nanotubes are dissolved in dichloromethane solution, and polyvinylpyrrolidone K30 is dissolved in dichloromethane as a dispersant. The mixture is stirred for 10 minutes, and ultrasonically cleaned with a bath-type ultrasonic cleaner for 5 minutes. After ultrasonication, the mixture is placed in ice water to cool and defoam, and then ultrasonication is continued until the carbon nanotubes are uniformly diffused. This process is repeated 12 times, with a total ultrasonic time of 60 minutes. The specific process of reducing the soluble polyether ether ketone resin in the aramid short fiber interlayer with added carbon nanotubes to crystalline polyether ether ketone through acidification reduction reaction is as follows: Hydrochloric acid solution is loaded into the liner of a hydrothermal synthesis reactor. The aramid short fiber interlayer with added carbon nanotubes is completely immersed in the hydrochloric acid solution. The liner is placed in the hydrothermal synthesis reactor and heated at 150°C for 12 hours. After removal, the mixture is washed with water and vacuum dried. Step 5: Graft crystalline polyetheretherketone (PEEK) onto a carbon nanotube-impregnated aramid fiber interlayer and a continuous carbon fiber reinforced PEEK prepreg tape of T700, 0.14 mm thickness, and 305 mm width, according to [07 / AF / 04]. s The symmetrical structure is placed in the mold in the following order: 7 layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction, followed by an aramid fiber interlayer. 8 more layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction, followed by another aramid fiber interlayer. 7 more layers of continuous carbon fiber reinforced polyether ether ketone prepreg tape are laid in the same direction. The mixture is then hot-pressed and demolded to obtain a toughened composite material with an aramid interlayer and added carbon nanotubes.

2. The method for preparing the aramid interlayer toughened composite material with added carbon nanotubes according to claim 1, characterized in that, In step 1, the compound dispersant is a composition of polyacrylamide, sodium dodecyl sulfate and polyethylene oxide in a mass ratio of 1:3:

6.

3. The method for preparing the aramid interlayer toughened composite material with added carbon nanotubes according to claim 1, characterized in that, In step 2, the volume ratio of hydrofluoric acid to water in the dilute hydrofluoric acid solution is 1:2, and the concentration of hydrofluoric acid is 48-55% w / w.

4. The method for preparing the aramid interlayer toughened composite material with added carbon nanotubes according to claim 1, characterized in that, In step 3, the preparation method of the soluble polyether ether ketone resin includes the following steps: synthesizing polyether ether ketone polymer monomers through Schiff base reaction; preparing end-amino end-capping agent monomers through Friedel-Crafts acylation and reduction reactions; carrying out stepwise polymerization of polyether ether ketone polymer monomers with biphenyl; and adding end-amino end-amino end-capping agent monomers in the later stage of polymerization to obtain amino-terminated soluble polyether ether ketone resin.

5. The method for preparing the aramid interlayer toughened composite material with added carbon nanotubes according to claim 1, characterized in that, In step 5, the specific hot pressing process is as follows: heating rate 15℃ / min, holding temperature 400℃, pressure 8MPa, holding time 40min, and cooling rate 15℃ / min.

6. A toughened composite material with an aramid interlayer reinforced with added carbon nanotubes, characterized in that, It is prepared using the preparation method described in any one of claims 1-5.

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