A modified bamboo-based fiber composite material and its preparation method

Abstract

This invention discloses a modified bamboo-based fiber composite material and its preparation method. Specifically, it relates to a modified bamboo-based fiber composite material, characterized by comprising the following components in parts by weight: 80-100 parts modified bamboo fiber, 70-90 parts epoxy resin, and 2-5 parts curing agent. The modified bamboo fiber is prepared through the following steps: Step 1: Immersing the bamboo fiber in a 10-15% sodium hydroxide solution at 70°C for 3-6 hours, then washing with water until neutral and drying; Step 2: Immersing the bamboo fiber treated in Step 1 in an aqueous mixture containing 0.6%-1.4% Grubbs catalyst, stirring and soaking for 12-24 hours; Step 3: Mixing the dried bamboo fiber treated in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 30-50:1 until homogeneous. The modified bamboo-based fiber composite material prepared by this invention exhibits good mechanical properties.

Description

Technical Field

[0001] This invention relates to the technical field of bamboo fiber composite materials, and in particular to a modified bamboo-based fiber composite material and its preparation method. Background Technology

[0002] Composite materials are materials composed of two or more materials with different properties combined in various ways. They can fully utilize the advantages of each component while overcoming the shortcomings of a single material, thereby expanding their application areas. Traditional composite materials, such as glass fiber, carbon fiber, and chemical fiber reinforcements, have excellent mechanical properties, but they also reveal many drawbacks during use: these materials usually rely on petrochemical raw materials, leading to significant resource consumption; the manufacturing process is complex and energy-intensive; and waste products are difficult to degrade, causing adverse environmental impacts. With increasing global attention to environmental issues, the limitations of traditional composite materials are prompting the materials industry to gradually shift towards green and ecological development.

[0003] With the deepening of the green development concept, green plant fibers are gradually replacing some traditional glass fiber materials, becoming an important component in the sustainable development of composite materials. This substitution is not limited to simple material replacement, but also reflects its comprehensive contribution to optimizing the performance and environmentally friendly properties of composite materials. Green plant fibers demonstrate irreplaceable advantages in achieving lightweighting, reducing carbon emissions, and improving biodegradability, and their application prospects are becoming increasingly clear.

[0004] Bamboo fiber stands out among numerous green plant fibers due to its unique growth advantages and structural characteristics, becoming a key driving force in the field of lightweight composite materials. Thanks to its excellent specific strength and specific modulus, bamboo fiber can significantly enhance the mechanical properties of composite materials, providing superior strength and stiffness. These properties make bamboo fiber materials an important solution for achieving lightweight goals in weight-sensitive applications, especially in the automotive and aerospace industries, and its potential value continues to be researched and confirmed.

[0005] Meanwhile, bamboo fiber reinforced composites have shown particularly strong performance in market applications. The automotive industry leverages their low density and high strength to significantly reduce vehicle weight, thereby improving fuel efficiency and reducing emissions; the construction industry uses bamboo fiber materials to develop high-strength, durable building components, effectively reducing resource consumption; and in the sporting goods sector, bamboo fiber's excellent toughness and heat resistance contribute to the development of high-performance lightweight equipment. These success stories further demonstrate the market potential of bamboo fiber composites across multiple fields, with demand showing rapid growth and a vast future development space.

[0006] However, currently, bamboo fiber composite materials have poor interfacial compatibility with hydrophilic groups and hydrophobic matrix resins, and the microscopic structure is uneven, which affects the overall performance of the composite materials. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a modified bamboo-based fiber composite material and its preparation method.

[0008] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0009] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0010] 80-100 parts of modified bamboo fiber;

[0011] 70-90 parts epoxy resin;

[0012] 2-5 parts of curing agent;

[0013] The modified bamboo fiber is prepared through the following steps:

[0014] Step 1: Immerse the bamboo fiber in a 10-15% sodium hydroxide solution at 70°C for 3-6 hours, then wash with water until neutral.

[0015] Step 2: Immerse the bamboo fiber treated in Step 1 in an aqueous solution containing 0.6%–1.4% (w / w) of Grubbs catalyst, stirring and soaking for 12–24 hours.

[0016] Step 3: Mix the dried bamboo fiber treated in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 30-50:1 until homogeneous. Then, dry it with hot air at 60°C for 4-6 hours until the moisture content of the bamboo fiber is less than 10%.

[0017] Furthermore, the average particle size of the dicyclopentadiene microcapsules is 2–8 μm.

[0018] Furthermore, the aqueous mixture of the Grubbs catalyst in step 2 also contains porous silica particles with a mass fraction of 0.1% to 0.2%.

[0019] Furthermore, the D50 particle size of the porous silica is controlled to be 10–100 μm.

[0020] Furthermore, the bamboo fiber is a mixed type of bamboo fiber consisting of bamboo green bundle fiber and bamboo flesh bundle fiber in a mass ratio of 20 to 30:1.

[0021] Furthermore, the average length of the bamboo fiber is 5 to 10 cm.

[0022] Furthermore, the aspect ratio of the bamboo fiber is 400 to 485.

[0023] Furthermore, it also includes 1 to 5 parts by weight of needle-shaped nano-calcium carbonate particles.

[0024] Furthermore, the needle-shaped nano-calcium carbonate particles have an average particle size of 35–50 nm and an aspect ratio of 15–20:1.

[0025] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0026] S1: After uniformly mixing the modified bamboo fiber with needle-shaped nano calcium carbonate particles, lay the mixture in a mold coated with a release agent.

[0027] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0028] S3: After covering with the upper mold, press at room temperature for 24-48 hours, then remove the mold to obtain the sample;

[0029] S4: Dry the sample in a drying oven at 70℃ for 6-8 hours.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] This invention modifies bamboo fiber, utilizing a strong alkaline effect to thoroughly remove impurities such as pectin and hemicellulose, reducing fiber polarity. Simultaneously, it imparts more and deeper grooves to the bamboo fiber surface, promoting the firm and uniform adhesion of Grubbs catalyst and dicyclopentadiene microcapsules. In this invention, the alkali concentration, treatment time, and temperature of the alkaline treatment are controlled within appropriate ranges to avoid excessive alkali treatment affecting the mechanical properties of the bamboo fiber, while also preventing insufficient alkali treatment from failing to form sufficiently uniform and deep surface grooves for the adhesion of Grubbs catalyst and dicyclopentadiene microcapsules. Secondly, by preferentially modifying bamboo fiber using Grubbs catalyst and dicyclopentadiene microcapsules, during the curing process of the epoxy resin in the composite material, bamboo fiber exhibits better compatibility with the resin. Furthermore, under the influence of internal stress and external pressure during epoxy resin curing, some microcapsules rupture on the surface of the bamboo fiber, releasing the internal dicyclopentadiene. This dicyclopentadiene then further cross-links with the epoxy resin under the action of the Grubbs catalyst, resulting in a more compact and stable composite structure. Simultaneously, the remaining unruptured dicyclopentadiene microcapsules can self-repair defects such as damage and cracks in the composite material during use, achieving a durable and long-lasting effect.

[0032] Furthermore, this invention incorporates the doping of porous silica during the bamboo fiber modification process. This improves the mechanical properties of the alkali-treated bamboo fiber while minimizing the loss of its inherent rough, grooved structure due to alkali corrosion. The increased porosity further enhances the specific surface area, thus facilitating the adsorption of dicyclopentadiene microcapsules on the bamboo fiber surface. Moreover, by adding needle-shaped nano-calcium carbonate particles and coordinating parameters such as the particle size and length of the bamboo fiber and the nano-calcium carbonate particles, the composite material's strength and toughness are improved during preparation. Simultaneously, the needle-shaped nano-calcium carbonate particles more readily cause the dicyclopentadiene microcapsules to break and fragment, better releasing dicyclopentadiene and improving the composite material's performance. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the embodiments.

[0034] The dicyclopentadiene microcapsules used in this invention are all microcapsules with urea-formaldehyde resin as the wall material and dicyclopentadiene as the core material.

[0035] Example 1

[0036] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0037] 80 parts of modified bamboo fiber;

[0038] 70 parts epoxy resin;

[0039] 2 parts curing agent;

[0040] Modified bamboo fiber is prepared through the following steps:

[0041] Step 1: Immerse the bamboo fiber in a 10% sodium hydroxide solution at 70°C for 3 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 20:1. The average length of the bamboo fiber is 5cm and the aspect ratio of the bamboo fiber is 400.

[0042] Step 2: Soak the bamboo fiber treated in Step 1 in an aqueous mixture containing 0.6% Grubbs catalyst by mass and stir for 12 hours. Then, dry it with hot air at 60°C for 4 hours until the moisture content of the bamboo fiber is less than 10%.

[0043] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 30:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 2μm.

[0044] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0045] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0046] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0047] S3: After covering with the upper mold, press at room temperature for 24 hours, then remove the mold to obtain the sample;

[0048] S4: Dry the sample in a drying oven at 70℃ for 6 hours.

[0049] Example 2

[0050] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0051] 100 parts of modified bamboo fiber;

[0052] 90 parts epoxy resin;

[0053] 5 parts curing agent;

[0054] Modified bamboo fiber is prepared through the following steps:

[0055] Step 1: Immerse the bamboo fiber in a 15% sodium hydroxide solution at 70°C for 6 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 30:1. The average length of the bamboo fiber is 10cm and the aspect ratio of the bamboo fiber is 485.

[0056] Step 2: Soak the bamboo fiber treated in Step 1 in an aqueous mixture containing 1.4% Grubbs catalyst by mass for 24 hours with stirring. Then, dry it with hot air at 60°C for 6 hours until the moisture content of the bamboo fiber is less than 10%.

[0057] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 50:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 8μm.

[0058] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0059] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0060] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0061] S3: After covering with the upper mold, press at room temperature for 48 hours, then remove the mold to obtain the sample;

[0062] S4: Dry the sample in a drying oven at 70℃ for 8 hours.

[0063] Example 3

[0064] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0065] 90 parts modified bamboo fiber;

[0066] 80 parts epoxy resin;

[0067] 3.5 parts curing agent;

[0068] Modified bamboo fiber is prepared through the following steps:

[0069] Step 1: Immerse the bamboo fiber in a 13% sodium hydroxide solution at 70°C for 4 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 25:1. The average length of the bamboo fiber is 7cm and the aspect ratio of the bamboo fiber is 442.

[0070] Step 2: Soak the bamboo fiber treated in Step 1 in an aqueous mixture containing 1.2% Grubbs catalyst by mass for 16 hours with stirring. Then, dry it with hot air at 60°C for 4 hours until the moisture content of the bamboo fiber is less than 10%.

[0071] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 40:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 6μm.

[0072] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0073] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0074] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0075] S3: After covering with the upper mold, press at room temperature for 36 hours, then remove the mold to obtain the sample;

[0076] S4: Dry the sample in a drying oven at 70℃ for 7 hours.

[0077] Example 4

[0078] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0079] 80 parts of modified bamboo fiber;

[0080] 70 parts epoxy resin;

[0081] 2 parts curing agent;

[0082] Modified bamboo fiber is prepared through the following steps:

[0083] Step 1: Immerse the bamboo fiber in a 10% sodium hydroxide solution at 70°C for 3 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 15:1. The average length of the bamboo fiber is 13cm and the aspect ratio of the bamboo fiber is 323.

[0084] Step 2: Soak the bamboo fiber treated in Step 1 in an aqueous mixture containing 0.6% Grubbs catalyst by mass and stir for 12 hours. Then, dry it with hot air at 60°C for 5 hours until the moisture content of the bamboo fiber is less than 10%.

[0085] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 30:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 2μm.

[0086] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0087] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0088] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0089] S3: After covering with the upper mold, press at room temperature for 24 hours, then remove the mold to obtain the sample;

[0090] S4: Dry the sample in a drying oven at 70℃ for 6 hours.

[0091] Example 5

[0092] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0093] 80 parts of modified bamboo fiber;

[0094] 70 parts epoxy resin;

[0095] 2 parts curing agent;

[0096] Modified bamboo fiber is prepared through the following steps:

[0097] Step 1: Immerse the bamboo fiber in a 10% sodium hydroxide solution at 70°C for 3 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 42:1. The average length of the bamboo fiber is 3cm and the aspect ratio of the bamboo fiber is 312.

[0098] Step 2: Soak the bamboo fiber treated in Step 1 in an aqueous mixture containing 0.6% Grubbs catalyst by mass and stir for 12 hours. Then, dry it with hot air at 60°C for 4 hours until the moisture content of the bamboo fiber is less than 10%.

[0099] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 30:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 2μm.

[0100] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0101] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0102] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0103] S3: After covering with the upper mold, press at room temperature for 24 hours, then remove the mold to obtain the sample;

[0104] S4: Dry the sample in a drying oven at 70℃ for 6 hours.

[0105] Example 6

[0106] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0107] 90 parts modified bamboo fiber;

[0108] 80 parts epoxy resin;

[0109] 3.5 parts curing agent;

[0110] Modified bamboo fiber is prepared through the following steps:

[0111] Step 1: Immerse the bamboo fiber in a 13% sodium hydroxide solution at 70°C for 4 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 25:1. The average length of the bamboo fiber is 7cm and the aspect ratio of the bamboo fiber is 442.

[0112] Step 2: The bamboo fiber treated in Step 1 is soaked in an aqueous mixture of 1.2% Grubbs catalyst by mass and stirred for 16 hours. Then, it is dried by hot air at 60°C for 4 hours until the moisture content of the bamboo fiber is less than 10%. The aqueous mixture of Grubbs catalyst also contains 0.15% porous silica particles by mass, and the D50 particle size of the porous silica is controlled to be 50 μm.

[0113] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 40:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 6μm.

[0114] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0115] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0116] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0117] S3: After covering with the upper mold, press at room temperature for 36 hours, then remove the mold to obtain the sample;

[0118] S4: Dry the sample in a drying oven at 70℃ for 7 hours.

[0119] Example 7

[0120] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0121] 90 parts modified bamboo fiber;

[0122] 80 parts epoxy resin;

[0123] 3.5 parts curing agent;

[0124] Modified bamboo fiber is prepared through the following steps:

[0125] Step 1: Immerse the bamboo fiber in a 13% sodium hydroxide solution at 70°C for 4 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 25:1. The average length of the bamboo fiber is 7cm and the aspect ratio of the bamboo fiber is 442.

[0126] Step 2: The bamboo fiber treated in Step 1 is soaked in an aqueous mixture of 1.2% Grubbs catalyst by mass and stirred for 16 hours. Then, it is dried by hot air at 60°C for 4 hours until the moisture content of the bamboo fiber is less than 10%. The aqueous mixture of Grubbs catalyst also contains 0.1% porous silica particles by mass, and the D50 particle size of the porous silica is controlled to be 10 μm.

[0127] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 40:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 60μm.

[0128] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0129] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0130] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0131] S3: After covering with the upper mold, press at room temperature for 36 hours, then remove the mold to obtain the sample;

[0132] S4: Dry the sample in a drying oven at 70℃ for 7 hours.

[0133] Example 8

[0134] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0135] 90 parts modified bamboo fiber;

[0136] 80 parts epoxy resin;

[0137] 3.5 parts curing agent;

[0138] Modified bamboo fiber is prepared through the following steps:

[0139] Step 1: Immerse the bamboo fiber in a 13% sodium hydroxide solution at 70°C for 4 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 25:1. The average length of the bamboo fiber is 7cm and the aspect ratio of the bamboo fiber is 442.

[0140] Step 2: The bamboo fiber treated in Step 1 is soaked in an aqueous mixture of 1.2% Grubbs catalyst by mass and stirred for 16 hours. Then, it is dried by hot air at 60°C for 6 hours until the moisture content of the bamboo fiber is less than 10%. The aqueous mixture of Grubbs catalyst also contains 0.2% porous silica particles by mass, and the D50 particle size of the porous silica is controlled to be 100 μm.

[0141] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 40:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 6μm.

[0142] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0143] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0144] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0145] S3: After covering with the upper mold, press at room temperature for 36 hours, then remove the mold to obtain the sample;

[0146] S4: Dry the sample in a drying oven at 70℃ for 7 hours.

[0147] Example 9

[0148] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0149] 90 parts modified bamboo fiber;

[0150] One part of needle-shaped nano-calcium carbonate particles;

[0151] 80 parts epoxy resin;

[0152] 3.5 parts curing agent;

[0153] Among them, the needle-shaped nano-calcium carbonate particles have an average particle size of 35 nm and an aspect ratio of 15:1.

[0154] Modified bamboo fiber is prepared through the following steps:

[0155] Step 1: Immerse the bamboo fiber in a 13% sodium hydroxide solution at 70°C for 4 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 25:1. The average length of the bamboo fiber is 7cm and the aspect ratio of the bamboo fiber is 442.

[0156] Step 2: The bamboo fiber treated in Step 1 is soaked in an aqueous mixture of 1.2% Grubbs catalyst by mass and stirred for 16 hours. Then, it is dried by hot air at 60°C for 6 hours until the moisture content of the bamboo fiber is less than 10%. The aqueous mixture of Grubbs catalyst also contains 0.15% porous silica particles by mass, and the D50 particle size of the porous silica is controlled to be 50 μm.

[0157] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 40:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 6μm.

[0158] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0159] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0160] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0161] S3: After covering with the upper mold, press at room temperature for 36 hours, then remove the mold to obtain the sample;

[0162] S4: Dry the sample in a drying oven at 70℃ for 7 hours.

[0163] Example 10

[0164] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0165] 90 parts modified bamboo fiber;

[0166] Five parts of needle-shaped nano-calcium carbonate particles;

[0167] 80 parts epoxy resin;

[0168] 3.5 parts curing agent;

[0169] Among them, the needle-shaped nano-calcium carbonate particles have an average particle size of 50 nm and an aspect ratio of 20:1.

[0170] Modified bamboo fiber is prepared through the following steps:

[0171] Step 1: Immerse the bamboo fiber in a 13% sodium hydroxide solution at 70°C for 4 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 25:1. The average length of the bamboo fiber is 7cm and the aspect ratio of the bamboo fiber is 442.

[0172] Step 2: The bamboo fiber treated in Step 1 is soaked in an aqueous mixture of 1.2% Grubbs catalyst by mass and stirred for 16 hours. Then, it is dried by hot air at 60°C for 6 hours until the moisture content of the bamboo fiber is less than 10%. The aqueous mixture of Grubbs catalyst also contains 0.15% porous silica particles by mass, and the D50 particle size of the porous silica is controlled to be 50 μm.

[0173] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 40:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 6μm.

[0174] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0175] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0176] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0177] S3: After covering with the upper mold, press at room temperature for 36 hours, then remove the mold to obtain the sample;

[0178] S4: Dry the sample in a drying oven at 70℃ for 7 hours.

[0179] Example 11

[0180] A modified bamboo-based fiber composite material comprises the following components in parts by weight:

[0181] 90 parts modified bamboo fiber;

[0182] Three portions of needle-shaped nano-calcium carbonate particles;

[0183] 80 parts epoxy resin;

[0184] 3.5 parts curing agent;

[0185] Among them, the needle-shaped nano-calcium carbonate particles have an average particle size of 37 nm and an aspect ratio of 17:1.

[0186] Modified bamboo fiber is prepared through the following steps:

[0187] Step 1: Immerse the bamboo fiber in a 13% sodium hydroxide solution at 70°C for 4 hours, then wash with water until neutral. The bamboo fiber is a mixture of bamboo green bundle fiber and bamboo flesh bundle fiber with a mass ratio of 25:1. The average length of the bamboo fiber is 7cm and the aspect ratio of the bamboo fiber is 442.

[0188] Step 2: The bamboo fiber treated in Step 1 is soaked in an aqueous mixture of 1.2% Grubbs catalyst by mass and stirred for 16 hours. Then, it is dried by hot air at 60°C for 4 hours until the moisture content of the bamboo fiber is less than 10%. The aqueous mixture of Grubbs catalyst also contains 0.15% porous silica particles by mass, and the D50 particle size of the porous silica is controlled to be 50 μm.

[0189] Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 40:1 until homogeneous; wherein the average particle size of the dicyclopentadiene microcapsules is 6μm.

[0190] A method for preparing a modified bamboo-based fiber composite material includes the following steps:

[0191] S1: The modified bamboo fiber is laid in a mold coated with a release agent;

[0192] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0193] S3: After covering with the upper mold, press at room temperature for 36 hours, then remove the mold to obtain the sample;

[0194] S4: Dry the sample in a drying oven at 70℃ for 7 hours.

[0195] Comparative Example 1

[0196] Bamboo-based fiber composite material, comprising the following components in parts by weight:

[0197] 80 parts bamboo fiber;

[0198] 70 parts epoxy resin;

[0199] 2 parts curing agent;

[0200] Its preparation method includes the following steps:

[0201] S1: Lay bamboo fiber into a mold coated with a release agent;

[0202] S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber.

[0203] S3: After covering with the upper mold, press at room temperature for 24 hours, then remove the mold to obtain the sample;

[0204] S4: Dry the sample in a drying oven at 70℃ for 6 hours.

[0205] Detection methods

[0206] Performance testing

[0207] The tensile strength and flexural strength of Examples 1-11 and Comparative Example 1 were tested as follows.

[0208] (1) Tensile strength shall be tested in accordance with GB / T1447-2005. Take dumbbell-shaped specimens with a size of 100mm×20mm×4mm. There are 5 specimens in each group. The upward loading speed of the clamp is 5mm / min.

[0209] (2) Bending strength was tested according to GB / T1449-2005 using a universal testing machine. The sample size was 80mm×15mm×4mm, with 5 samples per group. The downward loading speed of the loading roller was 2mm / min.

[0210] The test results are shown in Table 1 below.

[0211] Table 1

[0212]

[0213]

[0214] Conclusion: The test results above show that the composite material made by adding the modified bamboo fiber and epoxy resin of this invention has better tensile and flexural strength. Furthermore, the addition of porous silica particles and needle-like nano-calcium carbonate significantly improves both the tensile and flexural strength of the composite material.

[0215] The composite material samples of Examples 1, 6, 9 and Comparative Example 1 were bent into cracks using a universal testing machine. The samples were then placed at room temperature for 10 days before the cracks were observed. It was clear that the number and depth of cracks in Examples 1, 6, and 9 decreased sequentially, while there was no significant change in Comparative Example 1.

[0216] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A modified bamboo-based fiber composite material, characterized in that, The components include the following parts by weight: 80-100 parts of modified bamboo fiber; 70-90 parts epoxy resin; 2-5 parts of curing agent; The modified bamboo fiber is prepared through the following steps: Step 1: Immerse the bamboo fiber in a 10-15% sodium hydroxide solution at 70°C for 3-6 hours, then wash with water until neutral. Step 2: Soak the bamboo fiber treated in Step 1 in an aqueous mixture of 0.6% to 1.4% by mass of Grubbs catalyst, stir and soak for 12 to 24 hours, and then dry it with hot air at 60°C for 4 to 6 hours until the moisture content of the bamboo fiber is less than 10%. Step 3: Mix the dried bamboo fiber processed in Step 2 with dicyclopentadiene microcapsule powder at a mass ratio of 30-50:1 until homogeneous.

2. The modified bamboo-based fiber composite material according to claim 1, characterized in that, The average particle size of the dicyclopentadiene microcapsules is 2–8 μm.

3. The modified bamboo-based fiber composite material according to claim 1, characterized in that: The aqueous mixture of Grubbs catalyst in step 2 also contains porous silica particles with a mass fraction of 0.1% to 0.2%.

4. The modified bamboo-based fiber composite material according to claim 3, characterized in that: The D50 particle size of the porous silica is controlled to be 10–100 μm.

5. The modified bamboo-based fiber composite material according to claim 4, characterized in that: The bamboo fiber is a mixed type of bamboo fiber consisting of bamboo green bundle fiber and bamboo flesh bundle fiber in a mass ratio of 20 to 30:

1.

6. The modified bamboo-based fiber composite material according to claim 5, characterized in that: The average length of the bamboo fiber is 5 to 10 cm.

7. The modified bamboo-based fiber composite material according to claim 5, characterized in that: The aspect ratio of the bamboo fiber is 400 to 485.

8. The modified bamboo-based fiber composite material according to claim 5, characterized in that: It also includes 1 to 5 parts by weight of needle-shaped nano-calcium carbonate particles.

9. The modified bamboo-based fiber composite material according to claim 7, characterized in that: The needle-shaped nano-calcium carbonate particles have an average particle size of 35–50 nm and an aspect ratio of 15–20:

1.

10. A method for preparing a modified bamboo-based fiber composite material according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: After uniformly mixing the modified bamboo fiber with needle-shaped nano calcium carbonate particles, lay the mixture in a mold coated with a release agent. S2: After mixing epoxy resin and curing agent evenly, a mixed adhesive is obtained and applied evenly to the laid modified bamboo fiber. S3: After covering with the upper mold, press at room temperature for 24-48 hours, then remove the mold to obtain the sample; S4: Dry the sample in a drying oven at 70℃ for 6-8 hours.

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