Carbon fiber reinforced composite material with antibacterial property and preparation method thereof

Abstract

The application discloses a kind of carbon fiber reinforced antibacterial performance composite material and preparation method thereof, is specifically related to composite material technical field.The perilla aldehyde is reacted with aminothiourea first to obtain perilla aldehyde aminothiourea powder, then carbon fiber fabric is extracted by soxhlet and desized, activated by concentrated nitric acid, pretreated by immersing in coupling agent solution, then reacted with perilla aldehyde aminothiourea powder solution to obtain antibacterial carbon fiber fabric, then epoxy resin glue solution is prepared, finally, the hand lay-up method is used to lay layer, and the composite material is obtained by temperature programmed curing.The interface network of covalent bond connection is constructed between carbon fiber and epoxy resin matrix by coupling agent, which significantly improves the tensile, bending and impact strength, the bactericidal group is anchored on the surface of fiber by covalent bond, a stable antibacterial layer is formed, high efficient antibacterial rate can be maintained before and after aging, the synergistic unity of long-acting antibacterial performance and excellent mechanical property is realized, and the process is stable, suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a carbon fiber reinforced antibacterial composite material and its preparation method. Background Technology

[0002] With the rapid development of modern industry and the medical field, the demand for multifunctional materials is increasing. Composite materials that combine excellent mechanical properties with antibacterial properties are becoming the focus of industry research and application. Single-function materials are no longer sufficient to meet practical needs. In many fields such as aerospace, transportation, and healthcare, materials are required to have both high-strength, lightweight structural support capabilities and antibacterial and bacteriostatic functions to cope with the risk of microbial contamination and infection.

[0003] Carbon fiber, as a high-performance fiber material, possesses outstanding advantages such as high specific strength, high specific modulus, high temperature resistance, corrosion resistance, and good biocompatibility. Its reinforced composites have been widely used in aerospace, transportation, medical and health, food processing, and other fields, playing a crucial role in reducing structural weight and improving product performance. Combining antibacterial properties with carbon fiber reinforced composites can effectively inhibit the growth and spread of microorganisms, reduce the risk of microbial infection and contamination, and expand the application boundaries of carbon fiber composites. Currently, researchers mainly achieve antibacterial functions by introducing antibacterial components into the composite material system and modifying the carbon fiber surface with antibacterial properties. Through the synergistic effect between components, antibacterial properties are imparted to the material while retaining the excellent mechanical properties of carbon fiber, meeting the multifunctional and high-performance requirements of different fields.

[0004] Existing technologies for preparing carbon fiber reinforced antibacterial composites suffer from several substantial drawbacks, with each process exhibiting limitations to varying degrees. Traditional physical loading methods, such as impregnation, often result in uneven dispersion of the antibacterial components. Furthermore, the adhesion between the antibacterial agent and the carbon fiber / matrix is ​​primarily physical, leading to weak bonding and potential loss of functional substances during use. This results in poor stability and durability of the antibacterial properties. While some chemical modification methods can improve bonding strength, the complex reaction processes and stringent requirements for reaction condition control make them difficult to operate. Additionally, some chemical reagents can affect the mechanical properties of the carbon fiber itself, diminishing the core advantages of the composite material. Moreover, most preparation methods are costly and cumbersome, hindering large-scale mass production. Poor compatibility of some antibacterial agents further limits the industrial application and promotion of this type of composite material. Summary of the Invention

[0005] The main objective of this invention is to provide a carbon fiber reinforced antibacterial composite material and its preparation method, which can effectively solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a carbon fiber reinforced antibacterial composite material includes the following steps:

[0008] S1: Dissolve perillaldehyde in anhydrous ethanol and aminothiourea in a mixed solvent. Then, slowly add the aminothiourea solution to the perillaldehyde solution, add glacial acetic acid as a catalyst, and stir and reflux in an oil bath. After the reaction is completed, filter, wash with anhydrous ethanol, and dry at 45-55℃ to constant weight to obtain perillaldehyde aminothiourea powder.

[0009] S2: After desizing, rinsing and drying the carbon fiber fabric using a Soxhlet extractor, it is immersed in concentrated nitric acid at room temperature, then washed with water until neutral and vacuum dried to obtain a surface-activated carbon fiber reinforcement.

[0010] S3: The surface-activated carbon fiber reinforcement obtained in step S2 is pretreated by immersing it in a solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, then dried and immersed in a mixed solution of perillaldehyde thiourea powder and triethylamine in ethanol-water for 2-4 hours at 50-80°C. After drying, antibacterial carbon fiber fabric is obtained.

[0011] S4: Heating bisphenol A type epoxy resin to reduce viscosity, adding 2,4,6-tris(dimethylaminomethyl)phenol and curing agent and stirring evenly, and then vacuum degassing to obtain epoxy resin solution;

[0012] S5: The antibacterial carbon fiber fabric is placed into a mold coated with a release agent according to a predetermined layup method. Epoxy resin is poured using the hand layup method. After the mold is closed, it is cured by programmed temperature rise, cooled and demolded to obtain a composite material with carbon fiber reinforced antibacterial properties.

[0013] Preferably, the mass ratio of perillaldehyde to aminothiourea added in step S1 is (1.4-1.6):1, the reaction temperature is 65-75℃, and the reaction time is 1.5-2.5h.

[0014] Preferably, in step S1, the volume ratio of deionized water to anhydrous ethanol in the mixed solvent is 1:1, the volume ratio of added aminothiourea solution and perillaldehyde solution is 1:(1-3), and the amount of glacial acetic acid added is 0.5-2.0% of the total mass of perillaldehyde and aminothiourea.

[0015] Preferably, in step S2, acetone is used as the solvent for desizing. After Soxhlet extraction and reflux for 5-7 hours, the material is desizing and dried at 75-85°C for 1.5-2.5 hours. The mass fraction of concentrated nitric acid is 60-70%, and the treatment time at room temperature is 3-5 hours.

[0016] Preferably, the pretreatment in step S3 involves immersing the surface-activated carbon fiber reinforcement in an alcohol-water solution containing a coupling agent, soaking it at room temperature for 0.5-2 hours, and then removing and drying it.

[0017] Preferably, the amount of triethylamine used in step S3 is 1-5% of the mass of perillaldehyde thiourea powder.

[0018] Preferably, in step S4, the curing agent is at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, or methylnadic anhydride, and the mass ratio of the added curing agent to the bisphenol A type epoxy resin is (0.75-0.90):1, wherein the amount of 2,4,6-tris(dimethylaminomethyl)phenol added is 0.5-3.0% of the mass of the epoxy resin.

[0019] Preferably, in step S4, the bisphenol A epoxy resin is heated to a vacuum degassing temperature of 75-85°C for 15-25 minutes.

[0020] Preferably, the mass ratio of the antibacterial carbon fiber fabric to the epoxy resin solution added in step S5 is 1:(1.2-2.0).

[0021] Preferably, in step S5, the programmed temperature rise curing specifically involves raising the temperature from room temperature to 85-95°C at a rate of 1.5-2.5°C / min and holding it at that temperature for 1.5-2.5 hours; then raising the temperature to 115-125°C at the same rate and holding it at that temperature for 1.5-2.5 hours; finally raising the temperature to 135-145°C and holding it at that temperature for 1.5-2.5 hours; and then cooling it to below 50°C for demolding.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention utilizes the oxidation and activation of raw carbon fibers with concentrated nitric acid to generate abundant polar functional groups such as carboxyl and hydroxyl groups on the surface, and etches nanoscale trenches, providing dense micromechanical locking sites for epoxy resin and enhancing the physical anchoring effect. Through the hydrolysis and condensation of a silane coupling agent, a dense organic-inorganic hybrid molecular bridge is anchored on the surface, with one end connected to the fiber by a stable Si-OC covalent bond, and the other end retaining highly reactive epoxy groups. During the subsequent curing process with the resin matrix, these epoxy groups participate in the ring-opening crosslinking reaction, forming a continuous covalent bond pathway. The bonding force between the fiber and the matrix jumps from van der Waals forces to the dominant valence bond force, enabling external loads to be efficiently transferred from the matrix to the fiber body. The long-chain alkyl group of the silane coupling agent and the organic layer of the grafted antibacterial molecule form a flexible transition zone with a gradually changing modulus between the rigid fiber and the highly cross-linked resin. This can effectively relax the internal stress of curing and passivate the tips of microcracks generated under stress, preventing cracks from propagating along the interface, thereby simultaneously improving the interlaminar shear strength, flexural modulus and overall toughness of the composite material.

[0024] 2. This invention utilizes the nucleophilic ring-opening addition reaction between the terminal epoxy group of silane and the terminal amino group of perillaldehyde thiourea to covalently anchor the bactericidal group to the fiber surface via stable CN bonds. This forms a "molecular brush" structure that extends uniformly in a monolayer, with its hydrophobic perillyl group, Schiff base, and thion fully exposed. When bacteria come into contact with this interface, the perillyl group, acting as a hydrophobic anchor, rapidly inserts into the phospholipid bilayer of the cell membrane, disrupting the orderly arrangement of membrane lipids, leading to a sharp increase in permeability and causing leakage of contents such as potassium ions and nucleic acids, resulting in physical lysis and death of the bacteria. Simultaneously, the thion and Schiff base, as excellent soft-base ligands, can specifically chelate essential metal ions such as iron and copper in the bacterial respiratory chain enzyme system, inhibiting their energy metabolism. Because the bactericidal components are irreversibly anchored within the composite material, they will not dissolve or migrate with environmental changes, achieving the same lifespan as the material itself, fundamentally ensuring the safety and long-term effectiveness of the application.

[0025] 3. In this invention, the perillaldehyde thiourea molecules are grafted onto the fiber surface via an epoxy-amino ring-opening reaction. The newly generated linker structures are rich in secondary amines and hydroxyl groups. During the subsequent curing stages of the epoxy resin and acid anhydride, these linker arms spontaneously participate in the resin cross-linking reaction, directly integrating the originally independent antibacterial functional layer into the matrix's three-dimensional network. This further densifies the fiber-matrix interface layer, strengthening the interfacial bonding through the grafted molecules. Nitric acid activation simultaneously creates physical and chemical anchor points, while the silane coupling agent plays a crucial role in connecting the fiber, antibacterial agent, and resin, resulting in a comprehensive effect of high strength, high interfacial reliability, and excellent, durable antibacterial properties in the carbon fiber reinforced composite material. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for preparing a carbon fiber reinforced antibacterial composite material, the specific steps of which are as follows:

[0029] S1: Weigh 1.4g of perillaldehyde and 1.0g of aminothiourea. Dissolve 1.4g of perillaldehyde in 50mL of anhydrous ethanol and 1.0g of aminothiourea in a mixed solvent of 25mL of deionized water and 25mL of anhydrous ethanol. Slowly add the above 50mL aminothiourea solution dropwise to 50mL of perillaldehyde solution at a volume ratio of 1:1. Add 0.012g of glacial acetic acid as a catalyst. Under oil bath conditions at 65℃, stir and reflux at a rate of 300r / min for 1.5h. After the reaction is completed, filter and wash 3 times with 10mL of cold anhydrous ethanol each time. Dry at 45℃ to constant weight to obtain perillaldehyde aminothiourea powder.

[0030] S2: Place 10g of carbon fiber fabric into a Soxhlet extractor and desizing it with 100mL of acetone as solvent. After Soxhlet extraction and reflux for 5 hours, desizing is performed. The fabric is then rinsed with deionized water and dried at 75℃ for 1.5 hours. The dried carbon fiber fabric is then immersed in 60% concentrated nitric acid and treated at room temperature for 3 hours. After removal, it is washed with deionized water until neutral and then vacuum dried to obtain surface-activated carbon fiber reinforcement.

[0031] S3: The surface-activated carbon fiber reinforcement obtained in step S2 is immersed in 100 mL of an alcohol-water solution containing γ-(2,3-epoxypropoxy)propyltrimethoxysilane, wherein the volume ratio of alcohol to water is 1:1. The solution is pretreated by immersion at room temperature for 0.5 h. After drying, the solution is immersed in an ethanol-water mixed solution containing 1.0 g of perillaldehyde thiourea powder and 0.01 g of triethylamine, wherein 50 mL of ethanol and 50 mL of deionized water are used. The solution is reacted at 50 °C for 2 h. After drying, the antibacterial carbon fiber fabric is obtained.

[0032] S4: Take 20g of bisphenol A type epoxy resin, heat it at 75℃ to reduce viscosity, add 0.1g of 2,4,6-tris(dimethylaminomethyl)phenol and 15g of curing agent methyltetrahydrophthalic anhydride, stir evenly, and then degas under vacuum at 75℃ for 15 minutes to obtain epoxy resin solution.

[0033] S5: Take 10g of antibacterial carbon fiber fabric and place it into a mold coated with release agent according to the predetermined layup method. Pour 12g of epoxy resin liquid using the hand layup method. After closing the mold, perform programmed temperature rise curing. Specifically, heat from room temperature to 85℃ at a rate of 1.5℃ / min and hold for 1.5h. Then heat to 115℃ at the same rate and hold for 1.5h. Finally, heat to 135℃ and hold for 1.5h. Cool to below 50℃ and demold to obtain a composite material with carbon fiber reinforced antibacterial properties.

[0034] Example 2

[0035] A method for preparing a carbon fiber reinforced antibacterial composite material, the specific steps of which are as follows:

[0036] S1: Weigh 1.5g of perillaldehyde and 1.0g of aminothiourea. Dissolve 1.5g of perillaldehyde in 60mL of anhydrous ethanol, and dissolve 1.0g of aminothiourea in a mixed solvent of 30mL of deionized water and 30mL of anhydrous ethanol (volume ratio 1:1). Slowly add the above 60mL aminothiourea solution dropwise to 120mL of perillaldehyde solution at a volume ratio of 1:2. Add glacial acetic acid as a catalyst, with an addition amount of 0.03g. Under oil bath conditions at 70℃, stir and reflux at a rate of 400r / min for 2h. After the reaction is completed, filter, wash 3 times with 15mL of cold anhydrous ethanol each time, and dry at 50℃ to constant weight to obtain perillaldehyde aminothiourea powder.

[0037] S2: Take 10g of carbon fiber fabric, desize it using a Soxhlet extractor with 120mL of acetone as solvent, reflux for 6h after Soxhlet extraction, dry at 80℃ for 2h, then immerse it in 60mL of 65% concentrated nitric acid at room temperature for 4h, wash repeatedly with deionized water until neutral, and vacuum dry to obtain surface-activated carbon fiber reinforcement.

[0038] S3: The surface-activated carbon fiber reinforcement was immersed in 120 mL of an alcohol-water solution containing γ-(2,3-epoxypropoxy)propyltrimethoxysilane for 1.2 h of pretreatment at room temperature. After drying, it was immersed in an ethanol-water mixed solution containing 1.0 g of perillaldehyde thiourea powder and 0.03 g of triethylamine. The mixed solution consisted of 70 mL of ethanol and 70 mL of deionized water. The mixture was reacted at 65 °C for 3 h and dried to obtain the antibacterial carbon fiber fabric.

[0039] S4: Take 20g of bisphenol A type epoxy resin, heat it at 80℃ to reduce viscosity, add 0.36g of 2,4,6-tris(dimethylaminomethyl)phenol and 16.4g of curing agent methylhexahydrophthalic anhydride, stir evenly, and then degas under vacuum at 80℃ for 20 minutes to obtain epoxy resin solution.

[0040] S5: Take 10g of antibacterial carbon fiber fabric and place it into a mold coated with release agent according to the predetermined layup method. Pour 16g of epoxy resin liquid using the hand layup method. After closing the mold, perform programmed temperature rise curing. Specifically, heat the fabric from room temperature to 90℃ at a rate of 2.0℃ / min, hold for 2 hours, then heat it to 120℃ at the same rate, hold for 2 hours, and finally heat it to 140℃, hold for 2 hours. Cool it to below 50℃ and demold to obtain a composite material with carbon fiber reinforced antibacterial properties.

[0041] Example 3

[0042] A method for preparing a carbon fiber reinforced antibacterial composite material, the specific steps of which are as follows:

[0043] S1: Weigh 1.6g of perillaldehyde and 1.0g of aminothiourea. Dissolve 1.6g of perillaldehyde in 70mL of anhydrous ethanol and dissolve 1.0g of aminothiourea in a mixed solvent of 35mL of deionized water and 35mL of anhydrous ethanol. Slowly add the above 70mL aminothiourea solution dropwise to 210mL of perillaldehyde solution at a volume ratio of 1:3. Add 0.052g of glacial acetic acid as a catalyst. Under oil bath conditions at 75℃, stir and reflux at a rate of 500r / min for 2.5h. After the reaction is completed, filter, wash 3 times with 20mL of cold anhydrous ethanol each time, and dry at 55℃ to constant weight to obtain perillaldehyde aminothiourea powder.

[0044] S2: Take 10g of carbon fiber fabric, desize it using a Soxhlet extractor with 150mL of acetone as solvent, reflux for 7h after Soxhlet extraction, dry at 85℃ for 2.5h, then immerse it in 70mL of 70% concentrated nitric acid at room temperature for 5h, wash repeatedly with deionized water until neutral, and vacuum dry to obtain surface-activated carbon fiber reinforcement.

[0045] S3: The surface-activated carbon fiber reinforcement was immersed in 150 mL of an alcohol-water solution containing γ-(2,3-epoxypropoxy)propyltrimethoxysilane for 2 h of pretreatment at room temperature. After drying, it was immersed in an ethanol-water mixture containing 1.0 g of perillaldehyde thiourea powder and 0.05 g of triethylamine. The mixture consisted of 70 mL of ethanol and 70 mL of deionized water. The mixture was reacted at 80 °C for 4 h and then dried to obtain the antibacterial carbon fiber fabric.

[0046] S4: Take 20g of bisphenol A type epoxy resin, heat it at 85℃ to reduce viscosity, add 0.6g of 2,4,6-tris(dimethylaminomethyl)phenol and 18g of curing agent methylnadic anhydride, stir evenly, and then vacuum degas at 85℃ for 25 minutes to obtain epoxy resin solution.

[0047] S5: Take 10g of antibacterial carbon fiber fabric and place it into a mold coated with release agent according to the predetermined layup method. Pour 20g of epoxy resin liquid using the hand layup method. After closing the mold, perform programmed temperature rise curing. Specifically, heat from room temperature to 95℃ at a rate of 2.5℃ / min, hold for 2.5h, then heat to 125℃ at the same rate, hold for 2.5h, and finally heat to 145℃, hold for 2.5h. Cool to below 50℃ and demold to obtain a composite material with carbon fiber reinforced antibacterial properties.

[0048] Comparative Example 1

[0049] In step S3 of this comparative example, no coupling agent pretreatment is performed. The surface-activated carbon fiber reinforcement is directly reacted with perillaldehyde thiourea powder solution. The remaining steps are the same as in Example 2.

[0050] Comparative Example 2

[0051] In step S1 of this comparative example, the perilla aldehyde thiourea powder is not surface coated. The remaining steps are the same as in Example 2.

[0052] The following performance tests were conducted on the carbon fiber reinforced antibacterial composite materials prepared in Examples 1-3 and Comparative Examples 1-2:

[0053] 1. Antibacterial performance test

[0054] (I) Preparation of bacterial culture

[0055] Pour the nutrient agar medium, which has been sterilized by autoclaving (121℃, 30 min) and cooled, into sterile petri dishes, about 20 mL per dish. Let it stand and cool until solidified to prepare solid culture medium for later use.

[0056] Take out the E. coli culture, and in the clean bench, use a sterile cotton swab to pick up a small amount of the culture and inoculate it onto the prepared solid nutrient agar medium, spreading it evenly.

[0057] Place the inoculated culture medium in a constant temperature incubator with an accuracy of ±1℃, set the temperature to 37℃, and incubate statically for 18-24 hours until single colonies grow on the culture medium.

[0058] Inside the clean bench, a single E. coli colony is picked up with a sterile cotton swab and inoculated into a sterile centrifuge tube containing 10 mL of sterile physiological saline. The tube is then shaken to mix and prepare an initial bacterial suspension.

[0059] (ii) Antibacterial test

[0060] Take three antibacterial performance test samples prepared in Examples 1-3 and Comparative Examples 1-2. Wipe the surface of the sample with anhydrous ethanol to remove impurities, dry it with a hair dryer, and place it in a sterile culture dish after sterilization. Place one sample in each culture dish.

[0061] Inside the clean bench, use a 100μL pipette to draw 0.1mL of calibrated E. coli suspension and evenly drop it onto the surface of each sample. Gently spread it with a sterile cotton swab to ensure that the bacterial suspension evenly covers the sample surface without any missed areas.

[0062] Cover all the petri dishes containing the samples, label the samples, and place them in a 37°C constant temperature incubator for 24 hours to ensure that the bacterial solution is in full contact with the samples and exerts its antibacterial effect.

[0063] After the culture is completed, in the clean bench, use a 1mL pipette to draw 5mL of sterile physiological saline and slowly rinse the sample surface. Collect all the rinsing solution into a sterile centrifuge tube and shake for 1-2 minutes to evenly disperse the bacteria in the rinsing solution and prepare a mixture.

[0064] The above mixture was prepared into 10 using sterile physiological saline. -1 10 -2 10 -3 A gradient dilution of 1:1 was used, with 3 replicates for each gradient to ensure a sterile and uniform dilution process.

[0065] Using a 100μL pipette, take 0.1mL of different dilutions and add them to freshly prepared solid nutrient agar medium. Use a sterile glass scraper to spread the dilutions evenly on the surface of the medium and mark the gradients.

[0066] Place the smeared culture medium in a 37℃ constant temperature incubator and incubate statically for 18-24 hours. After the culture medium grows, count the colonies using a colony counter. Select dilution gradients with colony counts between 30 and 300 for statistical analysis and record the colony count for each gradient.

[0067] Take a sterile culture dish, without placing any sample, and add 0.1 mL of Escherichia coli suspension of the same concentration. The rest of the operation is the same as the above steps. After incubation, count the number of colonies in the blank control group.

[0068] Antibacterial rate (%) = (number of colonies in blank control group - number of colonies in sample group) / number of colonies in blank control group × 100%, calculate the antibacterial rate of each sample.

[0069] 2. Antibacterial stability test

[0070] The samples from Examples 1-3 and Comparative Examples 1-2 were placed in a UV aging test chamber to simulate 3 months of UV irradiation under natural conditions, with a wavelength of 365 nm and an irradiation intensity of 0.8 W / m². 2 Aging time: 72 hours.

[0071] After aging, the sample was removed, the surface was wiped with anhydrous ethanol, and then dried for later use. The antibacterial test steps were the same as those described above. The antibacterial rate of the aged sample against Escherichia coli and Staphylococcus aureus was tested. The antibacterial rate retention rate (%) = antibacterial rate after aging / antibacterial rate before aging × 100%. The experimental results are shown in Table 1.

[0072] 3. Mechanical property testing

[0073] (a) Tensile strength test

[0074] Take three tensile specimens prepared in each of Examples 1-3 and Comparative Examples 1-2. Use a vernier caliper with an accuracy of 0.02 mm to measure the width and thickness at three different points in the middle of each specimen. Record the data and take the average value as the actual size of the specimen.

[0075] Turn on the electronic universal testing machine with an accuracy of 0.01N, adjust the equipment to normal working condition, set an appropriate range according to the estimated strength of the carbon fiber composite material, adjust the tensile rate to 2mm / min, and wait for the equipment parameters to stabilize before use.

[0076] Select a set of specimens and clamp both ends of the specimens steadily on the fixtures of the testing machine, ensuring that the specimens are centered, without skewing or wrinkles. After confirming that the specimens are firmly clamped, start the electronic universal testing machine to perform a tensile test until the specimens break. The testing machine automatically records the maximum load at the time of breakage and simultaneously records the fracture morphology of the specimens.

[0077] Calculate the tensile strength using the formula: Tensile strength σ = F / (b × h), where F is the maximum load at fracture (N), b is the specimen width (mm), and h is the specimen thickness (mm). Calculate the tensile strength of a single specimen.

[0078] (ii) Bending strength test

[0079] Take three bending specimens (80mm×10mm×2mm) prepared in Examples 1-3 and Comparative Examples 1-2, and measure the width and thickness of each specimen with a vernier caliper with an accuracy of 0.02mm.

[0080] Switch the electronic universal testing machine to bending mode, adjust the equipment, set the bending rate to 1 mm / min, adjust the span to 60 mm based on the sample length of 80 mm, calibrate the equipment and set it for later use.

[0081] Place a single bending specimen smoothly on the support platform of the testing machine, ensuring that both ends of the specimen are tightly fitted to the support platform, the force is uniform, and there is no offset or looseness, so as to avoid the test data deviation caused by the specimen being placed crookedly.

[0082] Start the testing machine and apply a uniform bending load to the specimen until the specimen breaks or reaches the set deformation. Record the maximum bending load at this point (unit: N).

[0083] The bending strength is calculated using the formula: Bending strength σ = 3FL / (2bh²), where L is the span (60mm), F is the maximum bending load (N), b is the specimen width (mm), and h is the specimen thickness (mm). The bending strength of a single specimen is then calculated.

[0084] (III) Impact strength testing

[0085] Take impact specimens (80mm×10mm×2mm, no notch) prepared in Examples 1-3 and Comparative Examples 1-2, 3 specimens per group, measure the width and thickness of each specimen with a vernier caliper with an accuracy of 0.02mm, and record the average value of the 3 points.

[0086] Turn on the simply supported beam impact testing machine with a range of 0-50J, adjust the equipment, set the impact energy to 10J according to the estimated impact strength of the carbon fiber composite material, calibrate the position of the impact hammer, and ensure that the equipment is operating normally.

[0087] Place a single impact specimen smoothly on the support of the testing machine, adjust the specimen position to ensure that the specimen fits tightly with the support without loosening, and that the center of the specimen is aligned with the impact point of the impact hammer.

[0088] Start the testing machine, impact the specimen with the impact hammer, record the impact absorbed energy of the specimen (unit: J), observe the specimen fracture, and calculate the impact strength according to the formula: impact strength α=A / (bh), where A is the impact absorbed energy (J), b is the specimen width (mm), and h is the specimen thickness (mm). Calculate the impact strength of a single specimen. The experimental results are shown in Table 2.

[0089] Table 1: Test Table of Antibacterial Properties of Carbon Fiber Reinforced Antibacterial Composites

[0090] Sample number Initial concentration of Escherichia coli (CFU / mL) Colony count (CFU) in the blank control group Antibacterial rate of Escherichia coli before aging (%) Antibacterial rate of Staphylococcus aureus before aging (%) Antibacterial rate of aged Escherichia coli (%) Antibacterial rate of Staphylococcus aureus after aging (%) Antibacterial retention rate of Escherichia coli (%) Staphylococcus aureus antibacterial retention rate (%) Example 1 <![CDATA[8.2×10 6 ]]> 286 92.3 91.7 83.5 82.9 90.5 89.3 Example 2 <![CDATA[7.9×10 6 ]]> 278 95.7 94.9 88.6 87.8 92.6 92.5 Example 3 <![CDATA[8.5×10 6 ]]> 293 94.1 93.5 86.8 85.7 92.2 91.7 Comparative Example 1 <![CDATA[8.0×10 6 ]]> 281 94.9 94.2 87.2 86.5 91.9 91.8 Comparative Example 2 <![CDATA[8.1×10 6 ]]> 285 78.6 77.9 52.3 51.7 66.5 66.4

[0091] Table 2: Test Results of Mechanical Properties of Carbon Fiber Reinforced Antibacterial Composites

[0092] Sample number Maximum fracture load (N) Tensile strength (MPa) Maximum bending load (N) Bending strength (MPa) Impact absorbed energy (J) Impact strength (kJ / m²) Example 1 1786 358.2 892 451.3 4.92 24.7 Example 2 1923 384.6 968 480.2 5.35 26.7 Example 3 1896 377.5 945 475.8 5.21 25.9 Comparative Example 1 1615 323.0 798 396.0 4.32 21.7 Comparative Example 2 1889 379.1 937 469.8 5.18 25.9

[0093] Table 1 shows that Examples 1-3 exhibited high antibacterial rates against both *Escherichia coli* and *Staphylococcus aureus* before and after aging, with high antibacterial rate retention. Comparative Example 1, which did not undergo coupling agent pretreatment in step S3, directly reacted the surface-activated carbon fiber reinforcement with perillaldehyde thiourea powder solution, and its antibacterial performance was not significantly different from Examples 1-3. This indicates that coupling agent pretreatment has little impact on the antibacterial performance of the composite material, suggesting that the antibacterial performance mainly depends on the antibacterial agent itself and its bonding method with the carbon fiber, rather than the coupling agent pretreatment step.

[0094] Comparative Example 2 exhibited an extremely low antibacterial rate, which significantly decreased after aging. This indicates that simple physical adsorption or mixing cannot impart durable antibacterial properties to the material. The weak antibacterial activity of Comparative Example 2 may originate from residual groups with weak bactericidal properties on the fiber surface or from a very small amount of physically adsorbed antibacterial agent. Due to the lack of strong covalent bond anchoring, the antibacterial components are easily lost during aging and test rinsing, leading to a loss of long-term effectiveness.

[0095] In Examples 1-3, coupling agent pretreatment was performed to construct the bonding system. After surface activation with concentrated nitric acid, the carbon fiber surface formed a nanoscale rough structure and generated a large number of oxygen-containing functional groups. These functional groups reacted with the coupling agent to form stable Si-OC covalent bonds. The other end of the coupling agent then underwent ring-opening crosslinking with the epoxy resin, forming a dense interfacial bonding network. In contrast, Comparative Example 1 did not undergo coupling agent pretreatment, resulting in insufficient interfacial bonding and poor mechanical properties.

[0096] Table 2 shows that the mechanical property test results of Examples 1-3 are all high. The best mechanical property result of Example 2 proves that the grafting process not only introduces antibacterial function, but also that the secondary amine and hydroxyl groups generated in the reaction spontaneously act as active sites in the subsequent high-temperature curing, so that the antibacterial molecular layer directly participates in and is woven into the three-dimensional cross-linked network of epoxy resin-anhydride, achieving high strength and high modulus.

[0097] Comparative Example 1 exhibited the worst mechanical properties among all samples, showing a significant difference from the Example. This confirms that the interfacial bridging role of the silane coupling agent is indispensable. Comparative Example 1 lacked a coupling agent layer and could not form a continuous covalent bond pathway or construct a flexible interfacial layer with gradually changing modulus by relying solely on the physical wetting of the polar groups on the fiber surface and the weak hydrogen bonding with the resin.

[0098] In summary, the preparation method of the present invention, through steps such as nitric acid activation, silane coupling agent treatment, and covalent anchoring of bactericidal groups, enables the carbon fiber reinforced antibacterial composite material to possess both good antibacterial properties and antibacterial stability, as well as high mechanical properties.

[0099] In the description of this specification, the terms "preparation example," "example," "various examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that example or preparation example, which are included in at least one example or preparation example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same example or preparation example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more examples or preparation examples.

[0100] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon fiber reinforced antibacterial composite material, characterized in that, Includes the following steps: S1: Dissolve perillaldehyde in anhydrous ethanol and aminothiourea in a mixed solvent. Then, slowly add the aminothiourea solution to the perillaldehyde solution, add glacial acetic acid as a catalyst, and stir and reflux in an oil bath. After the reaction is completed, filter, wash with anhydrous ethanol, and dry at 45-55℃ to constant weight to obtain perillaldehyde aminothiourea powder. S2: After desizing, rinsing, and drying the carbon fiber fabric using a Soxhlet extractor, it is immersed in concentrated nitric acid at room temperature, then washed with water until neutral and vacuum dried to obtain a surface-activated carbon fiber reinforcement. S3: The surface-activated carbon fiber reinforcement obtained in step S2 is pretreated by immersing it in a solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, then dried and immersed in a mixed solution of perillaldehyde thiourea powder and triethylamine in ethanol-water for 2-4 hours at 50-80°C. After drying, antibacterial carbon fiber fabric is obtained. S4: Heating bisphenol A type epoxy resin to reduce viscosity, adding 2,4,6-tris(dimethylaminomethyl)phenol and curing agent and stirring evenly, then vacuum degassing to obtain epoxy resin liquid; S5: The antibacterial carbon fiber fabric is placed into a mold coated with a release agent according to a predetermined layup method. Epoxy resin is poured using the hand layup method. After the mold is closed, it is cured by programmed temperature rise, cooled and demolded to obtain a composite material with carbon fiber reinforced antibacterial properties.

2. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, The mass ratio of perillaldehyde to aminothiourea added in step S1 is (1.4-1.6):1, the reaction temperature is 65-75℃, and the reaction time is 1.5-2.5h.

3. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, In step S1, the volume ratio of deionized water to anhydrous ethanol in the mixed solvent is 1:1, the volume ratio of added aminothiourea solution and perillaldehyde solution is 1:(1-3), and the amount of glacial acetic acid added is 0.5-2.0% of the total mass of perillaldehyde and aminothiourea.

4. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, In step S2, acetone is used as the solvent for desizing. After Soxhlet extraction and reflux for 5-7 hours, the material is desizing and dried at 75-85℃ for 1.5-2.5 hours. The mass fraction of concentrated nitric acid is 60-70%, and the treatment time at room temperature is 3-5 hours.

5. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, The pretreatment in step S3 involves immersing the surface-activated carbon fiber reinforcement in an alcohol-water solution containing a coupling agent, soaking it at room temperature for 0.5-2 hours, and then removing and drying it.

6. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, In step S3, the amount of triethylamine used is 1-5% of the mass of perillaldehyde thiourea powder.

7. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, In step S4, the curing agent is at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, or methylnadic anhydride. The mass ratio of the added curing agent to the bisphenol A type epoxy resin is (0.75-0.90):1, wherein the amount of 2,4,6-tris(dimethylaminomethyl)phenol added is 0.5-3.0% of the mass of the epoxy resin.

8. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, In step S4, the bisphenol A epoxy resin is heated to the vacuum degassing temperature of 75-85℃ for 15-25 minutes.

9. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, The mass ratio of the antibacterial carbon fiber fabric to the epoxy resin solution added in step S5 is 1:(1.2-2.0).

10. The method for preparing a carbon fiber reinforced antibacterial composite material according to claim 1, characterized in that, In step S5, the programmed temperature rise and curing process involves heating from room temperature to 85-95℃ at a rate of 1.5-2.5℃ / min and holding at that temperature for 1.5-2.5h; then heating at the same rate to 115-125℃ and holding at that temperature for 1.5-2.5h; finally heating to 135-145℃ and holding at that temperature for 1.5-2.5h; and then cooling to below 50℃ for demolding.