Preparation method of bamboo fiber reinforced composite material for automotive interior

Abstract

The application relates to the technical field of composite materials, and discloses a preparation method of a bamboo fiber reinforced composite material for automobile interiors, which comprises the following raw materials in parts by weight: 45-50 parts of polypropylene, 45-50 parts of reinforcing materials and 1-5 parts of functional materials, wherein the reinforcing materials are composite bamboo fiber materials formed by loading bamboo cellulose nanofibers into modified short bamboo fiber bundles; and the modified short bamboo fiber bundles are prepared by surface modification of short bamboo fiber bundles through nanosol, so that the mechanical properties of the composite material are stronger.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, and in particular to a method for preparing bamboo fiber reinforced composite materials for automotive interiors. Background Technology

[0002] The widespread use of plastics has led to environmental problems. Therefore, developing natural fiber composite materials or fully biodegradable green composite materials is of great significance for reducing environmental impact. China is rich in bamboo, and bamboo fiber composite materials, used as materials for vehicle and ship hulls and interiors, can achieve lightweighting and fuel savings. They can replace ordinary engineering plastics and some glass fiber reinforced resin composites in civilian applications, reducing plastic usage, saving raw material resources, and are relatively easy to dispose of. Cellulose nanofibers have a large number of hydrogen bonds and a high specific surface area, making them prone to aggregation. Therefore, how to uniformly load cellulose nanofibers onto the surface of bamboo fiber bundles to promote efficient mechanical bonding at the interface of bamboo-plastic composites is one of the key problems that urgently needs to be solved. Meanwhile, wood fibers, bamboo fibers, hemp fibers, and other plant fibers have been extensively researched and developed. However, the improvement in the mechanical properties of bamboo fiber composites is limited, and the inherent advantages of plant fibers cannot yet be fully utilized. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing bamboo fiber reinforced composite materials for automotive interiors, which has the effects of increasing the contact area between bamboo fiber bundles and polypropylene resin, promoting mechanical interlocking, and enhancing the mechanical properties of the composite material.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for preparing a bamboo fiber reinforced composite material for automotive interiors, comprising the following parts by weight of raw materials: 45-50 parts of polypropylene, 45-50 parts of reinforcing material and 1-5 parts of functional material, wherein the reinforcing material is formed by loading bamboo cellulose nanofibers into modified short bamboo fiber bundles to form a composite bamboo fiber material; wherein the modified short bamboo fiber bundles are prepared by surface modification of short bamboo fiber bundles with nanosol.

[0005] A further provision of the present invention is that the functional material includes a silane coupling agent, maleic anhydride-grafted polypropylene, and an antioxidant.

[0006] A further provision of the present invention is that the short bamboo fiber bundles are prepared by the following steps: cutting the raw bamboo into bamboo strips of equal length, immersing the bamboo strips in a 4-5 wt% peroxyformic acid solution, reacting at 60-65°C for 50-70 min, rinsing the sample with deionized water until neutral after the reaction is completed, and drying to obtain short bamboo fiber bundles.

[0007] A further provision of the present invention is that the bamboo cellulose nanofibers are prepared by the following steps:

[0008] S1: Bamboo thin-wall tissue extraction: The original bamboo strips were crushed into bamboo powder of 30-60 mesh. The bamboo powder was added to pure water at a mass-volume ratio of 1g:15mL. After stirring and standing until stable, the upper sample was bamboo thin-wall tissue.

[0009] S2: Delignification: Bamboo parenchyma tissue with a solid-liquid ratio of 1:10 is mixed with 4wt% peracetic acid solution, the reaction temperature is 80-90℃, the reaction time is 40-50min, and the operation is repeated 3 times to obtain delignified parenchyma tissue.

[0010] S3: Washing: Immerse the delignified parenchyma tissue in a 0.01 mol / mL sodium hydroxide solution for 10-15 min, filter and wash with pure water to remove chemical residues to obtain delignified parenchyma tissue particles;

[0011] S4: Preparation of bamboo cellulose nanofibers: The solid-liquid ratio of delignified thin-walled tissue particles to water was controlled at 1:99. After mixing, the particles were crushed and diluted to a suspension with a concentration of 0.4wt%. The suspension was then transferred to a high-speed homogenizer and processed at 10,000 rpm for 10 min to obtain bamboo cellulose nanofibers.

[0012] A further provision of the present invention is that the modified short bamboo fiber bundle is prepared by the following steps: immersing the short bamboo fiber bundle in a nano-sol aqueous solution, stirring the nano-sol aqueous solution at room temperature using a magnetic stirrer at a uniform speed to ensure that the short bamboo fiber bundle and the sol aqueous solution are fully in contact and react, filtering, washing with deionized water, and finally placing at room temperature for 24 hours, and then drying in an oven at 80°C for 24 hours to obtain the modified short bamboo fiber bundle.

[0013] A further provision of the present invention is that the nanosol aqueous solution is prepared by the following steps: the precursor, hydrolysis agent, ammonia and deionized water are prepared into a sol with pH=8.5 in a certain proportion, and then the sol is placed in a water bath and stirred at 60°C for 3-4 hours to obtain the nanosol aqueous solution.

[0014] A further provision of the present invention is that the precursor is one of tetrabutyl titanate or tetraethyl silicate, and the hydrolysis agent is one of ethylene glycol or ethanol.

[0015] A further provision of the present invention is a method for preparing a bamboo fiber reinforced composite material for automotive interiors, comprising the following preparation steps: 45-50 parts of polypropylene, 45-50 parts of reinforcing material and 1-5 parts of functional material are added to a high-speed mixer for mixing, heated to 100-110℃ and stirred for 10-15 minutes, then the mixed material is added to an internal mixer for internal mixing, the mixed material is pulverized into granules by a pulverizer, dried and then fed into an injection molding machine for injection molding to obtain the bamboo fiber reinforced composite material.

[0016] A further provision of the present invention is that the preparation step of the reinforcing material is as follows: spraying 0.4wt% bamboo cellulose nanofiber suspension onto the surface of modified short bamboo fiber bundles, and then drying it in an oven at 100-105℃ for 24h, so that the bamboo cellulose nanofibers are fully loaded on the surface of the modified short bamboo fiber bundles, wherein the mass ratio of bamboo cellulose nanofiber suspension to modified short bamboo fiber bundles is 3-5:1.

[0017] The antioxidant is selected from one of 1010, 168, 1076, 164, 264, CA, DNP, DLTP, TNP, TPP and MB.

[0018] The beneficial effects of this invention are:

[0019] 1. The synergistic micro-nano reinforcement mechanism of bamboo fiber bundles and bamboo cellulose nanofibers in this invention selects bamboo fiber bundles with appropriate size as the first reinforcing phase of the composite material, so that the bamboo fiber bundles have excellent dispersibility in the polypropylene matrix and good stress transfer efficiency. The bamboo cellulose nanofibers loaded on the surface of the bamboo fiber bundles improve the interaction between the bamboo fiber bundles and polypropylene resin in the composite material through mechanical interlocking.

[0020] 2. Due to the similar material properties of bamboo fiber bundles and bamboo cellulose nanofibers, they exhibit excellent compatibility. The abundant hydrogen bonds and large specific surface area of ​​bamboo cellulose nanofibers enable them to form strong physical interactions with bamboo fiber bundles, self-assembling on the surface of the bamboo fiber bundles to form a stable porous network structure. This effectively increases the contact area between the bamboo fiber bundles and polypropylene resin, promotes mechanical interlocking, and improves the mechanical properties of the composite material. Simultaneously, during material processing, some bamboo cellulose nanofibers may detach from the surface of the bamboo fiber bundles and randomly disperse in the polypropylene matrix. These detached bamboo cellulose nanofibers can, on the one hand, increase the crystallinity of the polypropylene matrix, and on the other hand, serve as a secondary reinforcing phase at the submicron or even nanoscale of the composite material.

[0021] 3. Simultaneously, this invention uses tetrabutyl titanate nanosol or tetraethyl silicate nanosol to modify the surface of bamboo fiber bundles, depositing a small amount of nano-TiO2 particles and nano-SiO2 particles in situ in the micron-sized uneven pores on the surface of bamboo fiber bundles, constructing a rougher surface of a smaller scale, and improving the interfacial strength by utilizing the high rigidity of inorganic nanoparticles and the fact that the nano-size effect may cause changes in the crystallization behavior of the matrix resin in the interfacial region.

[0022] 4. The number of active groups on the surface of bamboo fiber bundles decreased after sol treatment. This is because a small amount of TiO2 or SiO2 nanoparticles were loaded onto the surface of the bamboo fiber bundles, reducing the reaction sites of CO- bonds and lowering the surface polarity. This helps to improve the bonding between the bamboo fiber bundles and polypropylene resin in the composite material. Simultaneously, the sol particles loaded on the surface of the bamboo fiber bundles delayed the thermal decomposition of the bamboo fiber bundles, further improving the stability of the composite material. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] A method for preparing bamboo fiber reinforced composite material for automotive interiors involves mixing 45-50 parts of polypropylene, 45-50 parts of reinforcing material, and 1-5 parts of functional materials (0.4-2 parts of silane coupling agent, 0.5-2 parts of maleic anhydride-grafted polypropylene, and 0.1-1 parts of antioxidant) in a high-speed mixer. The mixture is heated to 100-110℃ and stirred for 10-15 minutes. The resulting mixture is then fed into an internal mixer for intensive mixing. The intensively mixed material is pulverized into granules using a pulverizer, dried, and then fed into an injection molding machine for injection molding to obtain the bamboo fiber reinforced composite material.

[0026] The reinforcing material is a composite bamboo fiber material formed by loading bamboo cellulose nanofibers into modified short bamboo fiber bundles; the modified short bamboo fiber bundles are prepared by surface modification of the short bamboo fiber bundles with nanosol.

[0027] Example 2

[0028] A method for preparing bamboo fiber reinforced composite material for automotive interiors involves mixing 45-50 parts of polypropylene, 45-50 parts of reinforcing material, and 1-5 parts of functional materials (0.4-2 parts of silane coupling agent, 0.5-2 parts of maleic anhydride-grafted polypropylene, and 0.1-1 parts of antioxidant) in a high-speed mixer. The mixture is heated to 100-110℃ and stirred for 10-15 minutes. The resulting mixture is then fed into an internal mixer for intensive mixing. The intensively mixed material is pulverized into granules using a pulverizer, dried, and then fed into an injection molding machine for injection molding to obtain the bamboo fiber reinforced composite material.

[0029] The reinforcing material is modified short bamboo fiber bundles; the modified short bamboo fiber bundles are prepared by surface modification of short bamboo fiber bundles with nano-sol.

[0030] Example 3

[0031] A method for preparing bamboo fiber reinforced composite material for automotive interiors involves mixing 45-50 parts of polypropylene, 45-50 parts of reinforcing material, and 1-5 parts of functional materials (0.4-2 parts of silane coupling agent, 0.5-2 parts of maleic anhydride-grafted polypropylene, and 0.1-1 parts of antioxidant) in a high-speed mixer. The mixture is heated to 100-110℃ and stirred for 10-15 minutes. The resulting mixture is then fed into an internal mixer for intensive mixing. The intensively mixed material is pulverized into granules using a pulverizer, dried, and then fed into an injection molding machine for injection molding to obtain the bamboo fiber reinforced composite material.

[0032] The reinforcing material is a composite bamboo fiber material formed by loading bamboo cellulose nanofibers into short bamboo fiber bundles.

[0033] Example 4

[0034] A method for preparing bamboo fiber reinforced composite material for automotive interiors involves mixing 45-50 parts of polypropylene, 45-50 parts of reinforcing material, and 1-5 parts of functional materials (0.4-2 parts of silane coupling agent, 0.5-2 parts of maleic anhydride-grafted polypropylene, and 0.1-1 parts of antioxidant) in a high-speed mixer. The mixture is heated to 100-110℃ and stirred for 10-15 minutes. The resulting mixture is then fed into an internal mixer for intensive mixing. The intensively mixed material is pulverized into granules using a pulverizer, dried, and then fed into an injection molding machine for injection molding to obtain the bamboo fiber reinforced composite material.

[0035] The reinforcing material is short bamboo fiber bundles.

[0036] The performance of the bamboo fiber reinforced composite materials obtained in Examples 1-4 was tested, and the results are shown in the table below.

[0037] index Example 1 Example 2 Example 3 Example 4 Tensile strength (MPa) 96 92 89 86 Bending strength (MPa) 406 385 363 320 Impact strength (kJ / m²) 14 13 12 9 VOC emission (μg / m³) 40 40 36 35 Biodegradation rate (180 days) 95 95 94 90

[0038] In this invention, a synergistic micro-nano reinforcement mechanism of bamboo fiber bundles and bamboo cellulose nanofibers is employed. Bamboo fiber bundles of appropriate size are selected as the first reinforcing phase in the composite material, resulting in excellent dispersibility and good stress transfer efficiency within the polypropylene matrix. The bamboo cellulose nanofibers loaded on the surface of the bamboo fiber bundles enhance the interaction between the bamboo fiber bundles and the polypropylene resin within the composite material through mechanical interlocking. The numerous hydrogen bonds and large specific surface area of ​​the bamboo cellulose nanofibers enable them to form a strong physical interaction with the bamboo fiber bundles, self-assembling on the surface of the bamboo fiber bundles to form a stable porous network structure. This effectively increases the contact area between the bamboo fiber bundles and the polypropylene resin, promotes mechanical interlocking, and improves the mechanical properties of the composite material.

Claims

1. A method for preparing a bamboo fiber reinforced composite material for automotive interiors, characterized in that: It includes the following raw materials in parts by weight: 45-50 parts polypropylene, 45-50 parts reinforcing material and 1-5 parts functional material, wherein the reinforcing material is formed by loading bamboo cellulose nanofibers into modified short bamboo fiber bundles to form a composite bamboo fiber material. The modified short bamboo fiber bundles were prepared by surface modification of short bamboo fiber bundles using nano-sol. The functional materials include silane coupling agents, maleic anhydride-grafted polypropylene, and antioxidants. The bamboo cellulose nanofibers are prepared by the following steps: S1: Bamboo thin-wall tissue extraction: The original bamboo strips were crushed into bamboo powder of 30-60 mesh. The bamboo powder was added to pure water at a mass-volume ratio of 1g:15mL. After stirring and standing until stable, the upper sample was bamboo thin-wall tissue. S2: Delignification: Bamboo parenchyma tissue with a solid-liquid ratio of 1:10 is mixed with 4wt% peracetic acid solution, the reaction temperature is 80-90℃, the reaction time is 40-50min, and the operation is repeated 3 times to obtain delignified parenchyma tissue. S3: Washing: Immerse the delignified parenchyma tissue in a 0.01 mol / mL sodium hydroxide solution for 10-15 min, filter and wash with pure water to remove chemical residues to obtain delignified parenchyma tissue particles; S4: Preparation of bamboo cellulose nanofibers: The solid-liquid ratio of delignified thin-walled tissue particles to water was controlled at 1:

99. After mixing, the particles were crushed and diluted to a suspension with a concentration of 0.4wt%. The suspension was then transferred to a high-speed homogenizer and processed at 10,000 rpm for 10 min to obtain bamboo cellulose nanofibers.

2. The method for preparing a bamboo fiber reinforced composite material for automotive interiors according to claim 1, characterized in that: The short bamboo fiber bundles are prepared by the following steps: the raw bamboo is cut into bamboo strips of equal length, the bamboo strips are immersed in a 4-5 wt% peroxyformic acid solution, and reacted at 60-65℃ for 50-70 min. After the reaction is completed, the sample is rinsed with deionized water until neutral and then dried to obtain short bamboo fiber bundles.

3. The method for preparing a bamboo fiber reinforced composite material for automotive interiors according to claim 1, characterized in that: The modified short bamboo fiber bundles are prepared by the following steps: the short bamboo fiber bundles are soaked in a nano-sol aqueous solution, and the nano-sol aqueous solution is stirred at a constant speed with a magnetic stirrer at room temperature to ensure that the short bamboo fiber bundles and the sol aqueous solution are fully in contact and react. After filtration, the bundles are washed with deionized water, and finally placed at room temperature for 24 hours. Then, they are dried in an oven at 80°C for 24 hours to obtain the modified short bamboo fiber bundles.

4. The method for preparing a bamboo fiber reinforced composite material for automotive interiors according to claim 1, characterized in that: The nanosol aqueous solution is prepared by the following steps: the precursor, hydrolysis agent, ammonia and deionized water are prepared into a sol with pH=8.5 in a certain proportion, and then the sol is placed in a water bath and stirred at 60°C for 3-4 hours to obtain the nanosol aqueous solution.

5. The method for preparing a bamboo fiber reinforced composite material for automotive interiors according to claim 4, characterized in that: The precursor is one of tetrabutyl titanate or tetraethyl silicate, and the hydrolysis agent is one of ethylene glycol or ethanol.

6. The method for preparing a bamboo fiber reinforced composite material for automotive interiors according to claim 1, characterized in that: The antioxidant is selected from one of 1010, 168, 1076, 164, 264, CA, DNP, DLTP, TNP, TPP and MB.

7. The method for preparing a bamboo fiber reinforced composite material for automotive interiors according to claim 1, characterized in that: The preparation process includes the following steps: 45-50 parts of polypropylene, 45-50 parts of reinforcing material and 1-5 parts of functional material are put into a high-speed mixer for mixing, heated to 100-110℃ and stirred for 10-15 minutes, then the mixed material is put into an internal mixer for internal mixing, the mixed material is crushed into granules by a pulverizer, dried and then put into an injection molding machine for injection molding to obtain bamboo fiber reinforced composite material.