Preparation method of carbon nanotube reinforced composite material laminated plate

Abstract

The invention discloses a preparation method of a carbon nanotube reinforced composite material laminated plate, which is characterized in that stress is transmitted in a matrix or a bridge structure is formed at an interface of a fiber and the matrix through a carbon nanotube, so that the matrix performance and the interface bonding strength can be effectively improved. In various carbon nano tube-based carbon fiber reinforced polymer composite material reinforcing methods, a strategy of coating a carbon nano tube / epoxy resin glue solution by hand is selected, and the mass component of the carbon nano tube in the carbon fiber composite material can be effectively controlled, so that the mechanical property of a carbon fiber composite material laminated board is improved.

Description

Technical Field

[0001] The present invention relates to the field of helicopter composite materials, and particularly to a preparation method of a carbon nanotube reinforced composite laminate. Background Art

[0002] In the research and development of materials for helicopter rotor blades, the existing materials are difficult to meet the mechanical property requirements of future advanced helicopters with bearingless rotors.

[0003] Carbon nanotubes have excellent mechanical properties, a large tube length-to-diameter ratio, and specific surface area, making them very attractive polymer matrix fillers. The huge specific surface area of carbon nanotubes can enhance the interaction with the resin matrix, thus generating higher stress transfer and energy dissipation, and significantly improving the strength and toughness of the composite material. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a preparation method of a carbon nanotube reinforced composite laminate for the defects involved in the background art.

[0005] The present invention adopts the following technical solutions to solve the above technical problems: A preparation method of a carbon nanotube reinforced composite laminate includes the following steps: Step 1), uniformly mixing carbon nanotubes, a curing agent, epoxy resin, and an organic solvent to form a carbon nanotube dispersion solution; Step 2), removing the organic solvent from the carbon nanotube dispersion solution to obtain a uniformly mixed carbon nanotube / epoxy resin glue; Step 3), compounding the carbon nanotube / epoxy resin glue with carbon fiber, and then performing heating, pressurizing, curing, and demolding processing to obtain a laminate of a carbon nanotube / carbon fiber / epoxy resin three-phase composite material, that is, a carbon nanotube reinforced composite laminate.

[0006] As a further optimization scheme of the preparation method of a carbon nanotube reinforced composite laminate of the present invention, multi-walled carbon nanotubes are used as the carbon nanotubes.

[0007] As a further optimization scheme of the preparation method of a carbon nanotube reinforced composite laminate of the present invention, 2-ethyl-4-methylimidazole curing agent is used as the curing agent.

[0008] As a further optimization scheme of the preparation method of a carbon nanotube reinforced composite laminate of the present invention, E-51 type epoxy resin is used as the epoxy resin.

[0009] As a further optimization scheme of the preparation method of a carbon nanotube reinforced composite laminate of the present invention, acetone solution is used as the organic solvent.

[0010] As a further optimized scheme for the preparation method of a carbon nanotube-reinforced composite laminate of the present invention, the mass ratio of carbon nanotubes, curing agent, epoxy resin, and organic solvent is 1-5:1-40:10-40:100.

[0011] As a further optimized scheme for the preparation method of a carbon nanotube-reinforced composite laminate of the present invention, in step 1), mixing is carried out by mechanical stirring or ultrasonic dispersion.

[0012] As a further optimized scheme for the preparation method of a carbon nanotube-reinforced composite laminate of the present invention, when mixing is carried out by mechanical stirring, the rotation speed is 500 r / min and the time is 3 h; when mixing is carried out by ultrasonic dispersion, the ultrasonic frequency is 10 kHz, the power is 40 w, and the time is 30 min.

[0013] As a further optimized scheme for the preparation method of a carbon nanotube-reinforced composite laminate of the present invention, in step 2), the organic solvent is removed by heating and stirring.

[0014] As a further optimized scheme for the preparation method of a carbon nanotube-reinforced composite laminate of the present invention, in step 3), the uniformly mixed carbon nanotube / epoxy resin adhesive solution and carbon fiber are compounded in a mold by a hand lay-up molding process, and then heated, pressurized, cured, and demolded in a flat vulcanizer to prepare a laminate of a carbon nanotube / carbon fiber / epoxy resin three-phase composite material.

[0015] Compared with the prior art, the present invention adopts the above technical solutions and has the following technical effects: The present invention adds carbon nanotubes to the epoxy resin matrix to enhance the performance of the resin matrix, and after being compounded with carbon fiber, a high-performance composite material structure is made, resulting in a significant improvement in mechanical properties, which has important academic value and engineering significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a process schematic diagram of the present invention; Figure 2 is a curing process curve diagram of the carbon nanotube-reinforced composite laminate of the present invention; Figure 3 is a mechanical test curve diagram of the product obtained by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The technical solutions of the present invention will be further described in detail below with reference to the drawings: The present invention can be implemented in many different forms and should not be considered limited to the embodiments described herein. On the contrary, these embodiments are provided so that the present disclosure is thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, components are enlarged for clarity.

[0018] As Figure 1 shown, the present invention discloses a method for preparing a carbon nanotube reinforced composite laminate, comprising the following steps: Step 1), uniformly mixing carbon nanotubes, a curing agent, epoxy resin, and an organic solvent to form a carbon nanotube dispersion solution; Preferably, multi-walled carbon nanotubes are used as the carbon nanotubes, 2-ethyl-4-methylimidazole curing agent is used as the curing agent, E-51 type epoxy resin is used as the epoxy resin, and acetone solution is used as the organic solvent. The mass ratio of carbon nanotubes, curing agent, epoxy resin, and organic solvent is 1-5:1-40:10-40:100; during mixing, mechanical stirring or ultrasonic dispersion can be used; when using mechanical stirring for mixing, the rotation speed is 500 r / min and the time is 3 h; when using ultrasonic dispersion for mixing, the ultrasonic frequency is 10 kHz, the power is 40 w, and the time is 30 min.

[0019] Step 2), removing the organic solvent in the carbon nanotube dispersion solution by heating and stirring to obtain a uniformly mixed carbon nanotube / epoxy resin adhesive; Step 3), compounding the uniformly mixed carbon nanotube / epoxy resin adhesive with carbon fiber in a mold by hand lay-up molding process, and then performing heating, pressurizing, curing, and demolding processing in a flat vulcanizer to prepare a laminate of carbon nanotube / carbon fiber / epoxy resin three-phase composite material, that is, a carbon nanotube reinforced composite laminate.

[0020] The following is a specific example: We need to use a mold to complete the preparation. The mold is made of fiberglass products, with sufficient stiffness and strength, light weight, high durability, easy demolding, and low cost. The mold is divided into three parts, namely the upper template, the inner template, and the lower template. The inner template is sandwiched in the middle with a thickness of 2.1 mm and is a hollow structure. During the process of making the pressing plate, first, a release agent needs to be evenly sprayed on the surface of the mold to ensure that the subsequent product can be separated from the mold smoothly. After air drying, a layer of release paper needs to be pasted on the top of the lower template, the upper and lower surfaces of the inner template, and the bottom of the upper template, and at the same time, a layer of release agent is sprayed to prevent the resin adhesive from flowing onto the iron plate during the hot pressing process and facilitate demolding.

[0021] Weigh the corresponding masses of carbon nanotubes and epoxy resin according to the mass contents of carbon nanotubes of 0%, 2%, 3%, 4%, and 5%. Acetone is a low-viscosity organic solvent that can significantly reduce the overall viscosity of the system, thereby effectively improving the dispersion performance of carbon nanotubes in the epoxy resin matrix. In addition, acetone has a high volatility, with a boiling point of 56.5 °C under standard atmospheric pressure. After mixing evenly, acetone is volatilized by heating or standing, which will not affect the performance of the final cured system and plays an important role in the preparation and performance optimization of the material system. Mix the carbon nanotubes with the acetone solution and ultrasonically vibrate them in an ultrasonic cell disruptor for half an hour. During the ultrasonic vibration process, an ice bag should be placed in the container to prevent the carbon nanotubes from agglomerating due to the temperature rise during ultrasonic vibration. Add the ultrasonically vibrated multi-walled carbon nanotube dispersion to the epoxy resin solution, heat and stir in an oil bath at 60 °C, set the speed of the high-speed stirrer to 500 r / min, stir for three hours, then add 5% of the imidazole curing agent, and stir for half an hour. After that, the carbon nanotubes are evenly mixed into the epoxy resin solution, and the carbon nanotube / epoxy resin two-phase adhesive solution is prepared.

[0022] Unidirectional carbon fiber cloth generally needs to be cut in advance according to the size of the mold. Uniformly coat a layer of resin adhesive on the bottom layer of the mold. The resin adhesive is applied using a brush. The brush should be of a type with short and soft bristles to ensure uniform coating. During the coating process, the thickness of the resin adhesive should be controlled within the range that can completely wet the carbon fiber. During operation, the brush should be kept perpendicular to the coating surface and brushed in sequence from top to bottom to ensure the uniformity and full penetration of the coating. Then lay a layer of unidirectional carbon fiber cloth, and pay attention to removing air bubbles. When brushing, apply force along the radial direction of the unidirectional carbon fiber cloth and drive the air bubbles from the middle to both sides in one direction, and effectively remove the air bubbles entrapped between the fibers through repeated physical pressing operations to make the unidirectional carbon fiber cloth fit tightly. The precise application of resin should accompany the laying of each layer of fiber, with a uniform resin content, until the resin completely wets the fiber to achieve good interfacial bonding. Then apply another layer of resin adhesive on the unidirectional carbon fiber cloth and repeat this step. According to the design requirements, lay the carbon fiber reinforced material accurately in the mold according to the number of layers of the preset laying scheme, ensuring that each layer is laid along a single direction of the fiber, that is, unidirectional laying is implemented. In addition, it is required that the laying of the carbon fiber cloth must be kept flat until the designed thickness is reached. After the laying is completely wetted, apply a layer of resin adhesive on the top layer, place the release paper, and close the mold.

[0023] After laying and infiltrating all fiber layers, the step of mold closing and curing is required. Through heating and pressurizing, the resin system undergoes a curing reaction to form a stable cross-linked structure, aiming to shorten the molding cycle of the laminate. The mold after mold closing is placed in a flat vulcanizer for heating and pressurizing curing. The heating devices are the upper pressure plate heater and the lower pressure plate heater, and the pressurizing device is the hydraulic device at the bottom. The specific curing process flow is as follows: heat up to 80°C and keep warm for 20 minutes, apply a pressure of 2 Mpa, then heat up to 120°C, keep warm for 2 hours, then heat up to 150°C, keep warm for 1 hour, and finally cool to room temperature to release the pressure. The curing process curve is as Figure 2 shown. When the laminate in the mold cures to the demolding strength, the demolding step can be carried out.

[0024] Through demolding and processing operations, composite products with the required shape and performance can be obtained. When demolding, it should be noted that the temperature of the mold after heating and curing is very high. To prevent burns, protective clothing and high-temperature-resistant gloves should be worn. Take the mold out of the flat vulcanizer. At this time, a rubber hammer can be used as a tool to gently strike the periphery and surface of the mold with appropriate force, so that the laminate in the mold is slightly separated from the mold. The rubber tool can effectively prevent the mold from being scratched and damaged. When the mold cools down to room temperature, a scraper can be used to pry open a little gap at the edge of the mold, and then insert a wedge to open the mold and take out the laminate in the mold. When using the scraper and wedge for demolding, it should be noted not to damage the edge of the mold. After the laminate is pressed, the finished board is placed on a CNC machine tool and processed and cut according to the size requirements. At the same time, during the cutting process, it is necessary to pay attention to removing burrs, spurs, repairing the surface. If there are defective products, the defective products should be removed and the intact samples should be retained. The multi-walled carbon nanotube composite laminates with 0%, 2%, 3%, 4%, and 5% contents are prepared, Figure 3 which are the mechanical test results of the composite laminates.

[0025] Those skilled in the art of this technology can understand that, unless otherwise defined, all terms used here (including technical terms and scientific terms) have the same meaning as the general understanding of those of ordinary skill in the art in the field to which this invention belongs. It should also be understood that terms defined in general dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as here.

[0026] The specific embodiments described above have further detailed the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a carbon nanotube reinforced composite laminate, characterized in that, It includes the following steps: Step 1), uniformly mixing carbon nanotubes, a curing agent, epoxy resin and an organic solvent to form a carbon nanotube dispersion solution; Step 2), removing the organic solvent from the carbon nanotube dispersion solution to obtain a uniformly mixed carbon nanotube / epoxy resin adhesive; Step 3), compounding the carbon nanotube / epoxy resin adhesive with carbon fiber, and then performing heating, pressing and curing and demolding processing to obtain a laminate of a carbon nanotube / carbon fiber / epoxy resin three-phase composite material, namely a carbon nanotube-reinforced composite material laminate.

2. The preparation method of the carbon nanotube reinforced composite laminate according to claim 1, characterized in that, The carbon nanotubes used are multi-walled carbon nanotubes.

3. The preparation method of the carbon nanotube reinforced composite laminate according to claim 1, characterized in that, The curing agent used is 2-ethyl-4-methylimidazole curing agent.

4. The preparation method of the carbon nanotube reinforced composite laminate according to claim 1, characterized in that, The epoxy resin used is E-51 type epoxy resin.

5. The preparation method of the carbon nanotube reinforced composite laminate according to claim 1, characterized in that, The organic solvent used is acetone solution.

6. The preparation method of the carbon nanotube reinforced composite laminate according to claim 1, characterized in that, The mass ratio of the carbon nanotubes, the curing agent, the epoxy resin and the organic solvent is 1-5:1-40:10-40:

100.

7. The preparation method of the carbon nanotube reinforced composite laminate according to claim 1, characterized in that, In the said Step 1), mixing is carried out by mechanical stirring or ultrasonic dispersion.

8. The method for preparing a carbon nanotube reinforced composite laminate according to claim 7, characterized in that, When mixing is carried out by mechanical stirring, the rotation speed is 500 r / min and the time is 3 h; when mixing is carried out by ultrasonic dispersion, the ultrasonic frequency is 10 kHz, the power is 40 w and the time is 30 min.

9. The preparation method of the carbon nanotube reinforced composite laminate according to claim 1, characterized in that, In the said Step 2), the organic solvent is removed by heating and stirring.

10. The preparation method of the carbon nanotube reinforced composite laminate according to claim 1, characterized in that, In the said Step 3), the uniformly mixed carbon nanotube / epoxy resin adhesive and carbon fiber are compounded in a mold by a hand lay-up molding process, and then heating, pressing and curing and demolding processing are carried out in a flat vulcanizer to prepare a laminate of a carbon nanotube / carbon fiber / epoxy resin three-phase composite material.

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