A method for modifying bamboo fibers and its application in resin-based composite materials

Abstract

The application discloses a resin-based composite material containing modified bamboo fibers, and raw materials of the composite material include epoxy resin, acetone, the modified bamboo fibers and ethylenediamine. The modified bamboo fibers are added into the epoxy resin to form the composite material according to the method, so that the mechanical properties of the composite material can be remarkably improved, the epoxy resin matrix material can be applied to occasions with high stress demand, and the application range of the epoxy resin material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of application of bamboo fiber, and particularly relates to a modification method of bamboo fiber and application of the bamboo fiber in resin-based composite materials. BACKGROUND

[0002] The name of composite material originated in the 1940s, which refers to the combination of two or more than two materials with different chemical and physical properties, which is composed of a reinforcing body, a matrix and an interface between them, and is usually better than a single material in performance. However, many composite materials are not convenient for recycling, and cannot be degraded after the end of service life, causing great environmental problems. Plant fibers are low in cost, small in density, high in specific strength and specific modulus, and have the advantage of degradability, which meets the concept of sustainable development. Since the 1990s, plant fiber reinforced composites have gradually become a global research hotspot and have developed rapidly in many fields, such as packaging, biological medicine, construction, automotive field, etc.

[0003] Due to environmental concerns, people are paying more and more attention to plant fiber reinforced composites, and the research and development of such products are also rising. At present, the plant fibers used for composite reinforcement reported at home and abroad are various, such as sisal, flax, ramie, cotton fiber, bamboo fiber, sugarcane fiber, etc. Among them, bamboo fiber has high yield, high specific strength and modulus, light weight and low price, and has good development potential. Bamboo fiber is a fiber prepared by physical or chemical methods from bamboo, and its basic components are consistent with those of other types of plant fibers, which are cellulose, hemicellulose and lignin. In addition to low cost, high strength and good rigidity, bamboo fiber also has the functions of deodorization, antibacterial, sound insulation and ultraviolet resistance, so it has broad research prospects. SUMMARY

[0004] Therefore, the present application provides a modification method of bamboo fiber, comprising the following steps:

[0005] (1) configuring an aqueous solution of sodium hydroxide, immersing the bamboo fiber in the aqueous solution of sodium hydroxide for 3-4h, then solid-liquid separation, washing the solid phase with deionized water until the washing liquid is neutral, and then drying at 80℃ for more than 8h to obtain alkali washed bamboo fiber;

[0006] (2) configuring an aqueous solution of ethanol, adjusting pH of the aqueous solution of ethanol to 9 with 10wt% sodium hydroxide solution, then adding the alkali washed bamboo fiber into the solution to prepare a suspension, water-bath constant temperature of the suspension to 60±2℃ in nitrogen atmosphere, after constant temperature, stirring the suspension, adding vinyltriethoxysilane into the suspension under stirring, after completing the feeding, continuing to constant temperature of 60±2℃ in nitrogen atmosphere, stirring the suspension for more than 2h, then air cooling to normal temperature, solid-liquid separation, washing the solid phase with ethanol, drying at 60℃ for more than 5h, obtaining the first modified bamboo fiber;

[0007] (3) dispersing the first modified bamboo fiber in toluene to form a toluene suspension, water-bath constant temperature of the toluene suspension to 80±3℃ in nitrogen atmosphere, stirring the toluene suspension, then adding 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide into the toluene suspension under stirring, after completing the feeding, continuing to stir the toluene suspension at 80±3℃ in nitrogen atmosphere for more than 15h, condensing reflux during the constant temperature process, then air cooling to normal temperature, solid-liquid separation, washing the solid phase with ethanol for more than 3 times, drying at 60℃ for more than 1h, obtaining the second modified bamboo fiber;

[0008] (4) dispersing the second modified bamboo fiber in dimethyl sulfoxide to form a dimethyl sulfoxide suspension, water-bath constant temperature of the dimethyl sulfoxide suspension to 60±3℃, then stirring the dimethyl sulfoxide suspension, adding dimethylaminoethyl methacrylate and styrene into the suspension during the stirring process, after completing the feeding, constant temperature of 60±3℃ for 10-20min, then adding azobisisobutyronitrile under stirring, after completing the feeding, continuing to constant temperature of 60±3℃ for more than 4h, then solid-liquid separation, washing the solid phase with ethanol for more than 3 times, drying at 60℃ for more than 1h, obtaining the modified bamboo fiber.

[0009] Further, in the step (1), the mass percentage of sodium hydroxide in the aqueous solution of sodium hydroxide is 3%-5%, and the solvent is water; the solid-liquid mass ratio of the bamboo fiber soaked in the aqueous solution of sodium hydroxide is 1:50-100.

[0010] Further, in the step (2), the volume percentage of ethanol in the aqueous solution of ethanol is 50%-60%; the solid-liquid mass ratio of the suspension prepared by adding the alkali washed bamboo fiber into the solution is 1:50; the mass ratio of the added vinyltriethoxysilane to the alkali washed bamboo fiber in the suspension is vinyltriethoxysilane: alkali washed bamboo fiber = 6-8:1.

[0011] Further, in the step (3), the solid-liquid mass ratio of the primary modified bamboo fiber dispersed in toluene is solid / liquid=1:50; the mass ratio of 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the primary modified bamboo fiber in the toluene suspension is 3-isopropyl-dimethyl benzyl isocyanate:dibenzoyl peroxide:primary modified bamboo fiber=3-4:0.2-0.3:1.

[0012] Further, in the step (4), the solid-liquid mass ratio of the secondary modified bamboo fiber dispersed in dimethyl sulfoxide is solid / liquid=1:50; the mass ratio of dimethylaminoethyl methacrylate, styrene and azobisisobutyronitrile to the secondary modified bamboo fiber in the dimethyl sulfoxide suspension is dimethylaminoethyl methacrylate:styrene:azobisisobutyronitrile:secondary modified bamboo fiber=2-3:1-3:0.08-0.1:1.

[0013] The application further discloses a resin-based composite material containing the modified bamboo fiber.

[0014] Further, the weight fractions of the raw materials are as follows: epoxy resin 100 parts, acetone 12-16 parts, the modified bamboo fiber 5-10 parts and ethylenediamine 6-8 parts.

[0015] The preparation method of the resin-based composite material is as follows: the raw materials are weighed according to the weight fractions, the epoxy resin and the acetone are mixed to form a mixture, the mixture is kept in water bath at 80 DEG C, then the modified bamboo fiber is added to the mixture under stirring, the mixture is kept at 80 DEG C for 10-20 min after the addition, then the ethylenediamine is added, the mixture is kept at 80 DEG C for 5-8 min, then the mixture is poured into a mold and cooled, the resin-based composite material is obtained after curing at room temperature for more than 10 h.

[0016] The technical mechanism of the present application is that the present application is to graft macromolecular structure on the surface of the bamboo fiber by modifying the bamboo fiber, so as to eliminate the poor compatibility and poor binding force of the hydroxyl or phenolic hydroxyl group with the resin matrix. The bamboo fiber is modified by the method of the present application, first, the impurities and easily separated particles on the surface of the bamboo fiber are removed by alkali treatment, so as to avoid that the surface sharp part of the impurity particles becomes the source of the formation of micro-cracks of the resin matrix after subsequent compounding, thereby causing the strength of the material to decrease, and the alkali treatment is beneficial to improve the surface roughness of the bamboo fiber, thereby increasing the contact and binding area of the fiber and the resin matrix, and improving the binding force between the two phases. After the subsequent alkali treatment, the macromolecular groups are grafted on the surface of the bamboo fiber, thereby improving the wettability of the bamboo fiber and the resin, so that the bamboo fiber and the resin matrix are combined more closely, and it is not easy to produce large gaps and holes at the interface between the two phases. At the same time, after the macromolecular groups are grafted, the dispersibility of the bamboo fiber is improved, the agglomeration degree of the bamboo fiber is reduced, thereby making the fiber more uniformly distributed in the resin matrix, and it is not easy to produce local stress concentration or deformation cracking, thereby improving the overall strength of the material.

[0017] The present application has the beneficial effect that the bamboo fiber is modified according to the method of the present application and then added into the epoxy resin to form a composite material, which can significantly improve the mechanical properties of the composite material, so that the epoxy resin matrix material can be applied to occasions with high stress demand, thereby improving the application range of the epoxy resin material. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Tensile property comparison chart of the resin matrix composite material prepared by the method described in each example and comparative example. DETAILED DESCRIPTION

[0019] The present application will be further described below in combination with examples.

[0020] Example 1

[0021] A modification method of bamboo fiber, the steps comprising:

[0022] (1) An aqueous solution of sodium hydroxide is configured, the mass percentage of sodium hydroxide in the aqueous solution of sodium hydroxide is 3%, and the solvent is water; the bamboo fiber (fiber length 3-6 cm, diameter 15-21 μm) is soaked in the aqueous solution of sodium hydroxide for 3 h, the solid-liquid mass ratio of the bamboo fiber soaked in the aqueous solution of sodium hydroxide is 1:50; then the solid-liquid separation is carried out, the solid phase is washed with deionized water until the washing liquid is neutral, and then dried at 80℃ for 8 h, to obtain alkali washed bamboo fiber;

[0023] (2) configure the aqueous solution of ethanol, the volume percentage of ethanol in the aqueous solution of ethanol is 50%; adjust the pH of the aqueous solution of ethanol to 9 with 10wt% sodium hydroxide solution, then add the alkali washed bamboo fiber into the solution to prepare a suspension, the solid-liquid mass ratio of the alkali washed bamboo fiber added into the solution to prepare a suspension is 1:50; the suspension is water bathed in a nitrogen atmosphere to constant temperature at 60±2℃, after constant temperature, the suspension is stirred, and then vinyltriethoxysilane is added to the suspension under stirring, the mass ratio of the added vinyltriethoxysilane to the alkali washed bamboo fiber in the suspension is vinyltriethoxysilane: alkali washed bamboo fiber = 6:1; after the addition is completed, the suspension is continuously stirred at 60±2℃ in a nitrogen atmosphere for 2h, and then air-cooled to room temperature, solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 5h to obtain the first modified bamboo fiber;

[0024] (3) disperse the first modified bamboo fiber in toluene to form a toluene suspension, the solid-liquid mass ratio of the first modified bamboo fiber dispersed in toluene is solid / liquid = 1:50; the toluene suspension is water bathed in a nitrogen atmosphere to constant temperature at 80±3℃, the toluene suspension is stirred, then 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide are added to the toluene suspension under stirring, the mass ratio of the added 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the first modified bamboo fiber in the toluene suspension is 3-isopropyl-dimethyl benzyl isocyanate:dibenzoyl peroxide: first modified bamboo fiber = 3:0.2:1; after the addition is completed, the toluene suspension is continuously stirred at 80±3℃ in a nitrogen atmosphere for 15h, and then air-cooled to room temperature, solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 1h to obtain the second modified bamboo fiber;

[0025] (4) disperse the second modified bamboo fiber in dimethyl sulfoxide to form a dimethyl sulfoxide suspension, the solid-liquid mass ratio of the second modified bamboo fiber dispersed in dimethyl sulfoxide is solid / liquid = 1:50; the dimethyl sulfoxide suspension is water bathed to constant temperature at 60±3℃, then the dimethyl sulfoxide suspension is stirred, and then dimethylaminoethyl methacrylate and styrene are added to the suspension during stirring, after the addition is completed, the suspension is stirred at 60±3℃ for 10min, then azobisisobutyronitrile is added to the suspension under stirring, the mass ratio of the added dimethylaminoethyl methacrylate, styrene and azobisisobutyronitrile to the second modified bamboo fiber in the dimethyl sulfoxide suspension is dimethylaminoethyl methacrylate: styrene: azobisisobutyronitrile: second modified bamboo fiber = 2:1:0.08:1; after the addition is completed, the suspension is continuously stirred at 60±3℃ for 4h, and then solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 1h to obtain the modified bamboo fiber.

[0026] A resin-based composite material containing the modified bamboo fiber, the raw materials of the composite material including: epoxy resin, acetone, the modified bamboo fiber and ethylenediamine. The weight ratio of each raw material is: epoxy resin 100 parts, acetone 12 parts, the modified bamboo fiber 5 parts, and ethylenediamine 6 parts.

[0027] The preparation method of the resin-based composite material is as follows: each raw material is weighed according to the weight ratio, the epoxy resin and the acetone are mixed to form a mixture, the mixture is water-bathed and kept at 80°C, then the modified bamboo fiber is added to the mixture under stirring, the mixture is kept at 80°C for 10 minutes after the addition, then the ethylenediamine is added, and the mixture is stirred at 80°C for 5 minutes, then poured into a mold and cooled, and cured at room temperature for 10 hours to obtain the resin-based composite material.

[0028] Example 2

[0029] A modification method of a bamboo fiber, the steps including:

[0030] (1) An aqueous solution of sodium hydroxide is configured, the mass percentage of sodium hydroxide in the aqueous solution being 4%, and the solvent being water; the bamboo fiber (fiber length 3-6 cm, diameter 15-21 μm) is soaked in the aqueous solution of sodium hydroxide for 3 hours, the solid-liquid mass ratio of the bamboo fiber in the aqueous solution of sodium hydroxide being 1:50; then the solid-liquid separation is performed, the solid phase is washed with deionized water until the liquid after washing is neutral, and then the solid phase is dried at 80°C for 8 hours to obtain alkali-washed bamboo fiber;

[0031] (2) An aqueous solution of ethanol is configured, the volume percentage of ethanol in the aqueous solution being 50%; the pH of the aqueous solution of ethanol is adjusted to 9 with a 10wt% sodium hydroxide solution, then the alkali-washed bamboo fiber is added to the solution to prepare a suspension, the solid-liquid mass ratio of the suspension being 1:50; the suspension is water-bathed and kept at 60±2°C in a nitrogen atmosphere, then the suspension is stirred after keeping, the vinyltriethoxysilane is added to the suspension under stirring, the mass ratio of the added vinyltriethoxysilane to the alkali-washed bamboo fiber in the suspension being 7:1; after the addition is completed, the suspension is kept at 60±2°C in the nitrogen atmosphere and stirred for 2 hours, then air-cooled to room temperature, the solid-liquid separation is performed, the solid phase is washed with ethanol for 3 times, and then dried at 60°C for 5 hours to obtain the first modified bamboo fiber;

[0032] (3) dispersing the primary modified bamboo fibers in toluene to form a toluene suspension, the solid-liquid mass ratio of the primary modified bamboo fibers dispersed in toluene being solid / liquid = 1:50; water-bath constant temperature of the toluene suspension to 80±3℃ in a nitrogen atmosphere, stirring the toluene suspension, then adding 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the toluene suspension in a stirring state, the mass ratio of 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the primary modified bamboo fibers in the toluene suspension being 3-isopropyl-dimethyl benzyl isocyanate:dibenzoyl peroxide:primary modified bamboo fibers = 3:0.2:1; after the completion of feeding, continuing to stir the toluene suspension at 80±3℃ in a nitrogen atmosphere for 15h, condensing reflux in the process of constant temperature, then air cooling to room temperature, solid-liquid separation, washing the solid phase with ethanol for 3 times, drying at 60℃ for 1h, obtaining secondary modified bamboo fibers;

[0033] (4) dispersing the secondary modified bamboo fibers in dimethyl sulfoxide to form a dimethyl sulfoxide suspension, the solid-liquid mass ratio of the secondary modified bamboo fibers dispersed in dimethyl sulfoxide being solid / liquid = 1:50; water-bath constant temperature of the dimethyl sulfoxide suspension to 60±3℃, then stirring the dimethyl sulfoxide suspension, adding dimethylaminoethyl methacrylate and styrene to the suspension in the process of stirring, after the completion of feeding, constant temperature stirring of the suspension at 60±3℃ for 10min, then adding azobisisobutyronitrile in a stirring state, the mass ratio of dimethylaminoethyl methacrylate, styrene, azobisisobutyronitrile to the secondary modified bamboo fibers in the dimethyl sulfoxide suspension being dimethylaminoethyl methacrylate:styrene:azobisisobutyronitrile:secondary modified bamboo fibers = 2:2:0.09:1; after the completion of feeding, continuing to constant temperature stirring of the suspension at 60±3℃ for 4h, then solid-liquid separation, washing the solid phase with ethanol for 3 times, drying at 60℃ for 1h, obtaining modified bamboo fibers.

[0034] A resin-based composite material containing the modified bamboo fibers described above, the raw materials of the composite material including: epoxy resin, acetone, the modified bamboo fibers and ethylenediamine. The weight fractions of each raw material are: epoxy resin 100 parts, acetone 14 parts, the modified bamboo fibers 7 parts, ethylenediamine 7 parts.

[0035] The preparation method of the resin-based composite material described above is: taking each raw material according to the weight fractions described above, mixing the epoxy resin and acetone to form a mixture, water-bath constant temperature of the mixture to 80℃, then adding the modified bamboo fibers to the mixture in a stirring state, after feeding, continuing to constant temperature stirring of the mixture at 80℃ for 10min, then adding the ethylenediamine, constant temperature stirring at 80℃ for 5min, pouring into a mold to cool, curing at room temperature for 10h, obtaining the resin-based composite material.

[0036] Example 3

[0037] A modification method of bamboo fiber, steps include:

[0038] (1) configure the aqueous solution of sodium hydroxide, the mass percentage of sodium hydroxide in the aqueous solution of sodium hydroxide is 4%, and the solvent is water; the bamboo fiber (fiber length 3-6 cm, diameter 15-21 μm) is soaked in the aqueous solution of sodium hydroxide for 3 h, and the solid-liquid mass ratio of the bamboo fiber soaked in the aqueous solution of sodium hydroxide is 1:50; then solid-liquid separation, the solid phase is washed with deionized water until the washing liquid is neutral, and then dried at 80℃ for 8 h, to obtain alkali washed bamboo fiber;

[0039] (2) configure the aqueous solution of ethanol, the volume percentage of ethanol in the aqueous solution of ethanol is 50%; adjust the pH of the aqueous solution of ethanol to 9 with 10wt% sodium hydroxide solution, then add the alkali washed bamboo fiber to the solution to prepare a suspension, the solid-liquid mass ratio of the suspension prepared by adding the alkali washed bamboo fiber to the solution is 1:50; the suspension is kept at 60±2℃ in a nitrogen atmosphere water bath, after keeping, the suspension is stirred, and vinyltriethoxysilane is added to the suspension under stirring, the mass ratio of the added vinyltriethoxysilane to the alkali washed bamboo fiber in the suspension is vinyltriethoxysilane: alkali washed bamboo fiber = 7:1; after the addition is completed, the suspension is continuously kept at 60±2℃ in a nitrogen atmosphere for 2 h, and then air-cooled to room temperature, solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 5 h, to obtain the first modified bamboo fiber;

[0040] (3) disperse the first modified bamboo fiber in toluene to form a toluene suspension, the solid-liquid mass ratio of the first modified bamboo fiber dispersed in toluene is solid / liquid = 1:50; keep the toluene suspension at 80±3℃ in a nitrogen atmosphere water bath, stir the toluene suspension, then add 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the toluene suspension under stirring, the mass ratio of the added 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the first modified bamboo fiber in the toluene suspension is 3-isopropyl-dimethyl benzyl isocyanate:dibenzoyl peroxide: first modified bamboo fiber = 4:0.3:1; after the addition is completed, continue to stir the toluene suspension at 80±3℃ in a nitrogen atmosphere for 15 h, condense reflux during keeping, then air-cooled to room temperature, solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 1 h, to obtain the second modified bamboo fiber;

[0041] (4) dispersing the secondary modified bamboo fiber in dimethyl sulfoxide to form a dimethyl sulfoxide suspension, the solid-liquid mass ratio of the secondary modified bamboo fiber dispersed in the dimethyl sulfoxide being solid / liquid = 1:50; water-bath constant temperature of the dimethyl sulfoxide suspension to 60±3℃, then stirring the dimethyl sulfoxide suspension, adding dimethylaminoethyl methacrylate and styrene to the suspension during the stirring process, after the completion of the feeding, constant temperature of the suspension to 60±3℃ for 10 min, then adding azobisisobutyronitrile under the stirring state, the mass ratio of the dimethylaminoethyl methacrylate, styrene and azobisisobutyronitrile to the secondary modified bamboo fiber in the dimethyl sulfoxide suspension being dimethylaminoethyl methacrylate:styrene:azobisisobutyronitrile:secondary modified bamboo fiber = 3:2:0.09:1; after the completion of the feeding, constant temperature of the suspension to 60±3℃ for 4 h, then solid-liquid separation, washing the solid phase with ethanol for 3 times, drying at 60℃ for 1 h, obtaining the modified bamboo fiber.

[0042] A resin-based composite material containing the modified bamboo fiber, the raw materials of the composite material including: epoxy resin, acetone, the modified bamboo fiber and ethylenediamine. The weight fractions of the raw materials are: epoxy resin 100 parts, acetone 14 parts, the modified bamboo fiber 8 parts and ethylenediamine 7 parts.

[0043] The preparation method of the resin-based composite material is: taking the raw materials according to the weight fractions, mixing the epoxy resin and acetone to form a mixture, water-bath constant temperature of the mixture to 80℃, then adding the modified bamboo fiber to the mixture under the stirring state, after the feeding, constant temperature of the mixture to 80℃ for 10 min, then adding the ethylenediamine, constant temperature of the mixture to 80℃ for 5 min, pouring into a mold to cool, curing at room temperature for 10 h, obtaining the resin-based composite material.

[0044] Example 4

[0045] A modification method of bamboo fiber, the steps including:

[0046] (1) configuring an aqueous solution of sodium hydroxide, the mass percentage of sodium hydroxide in the aqueous solution being 5%, and the solvent being water; soaking bamboo fiber (fiber length 3-6 cm, diameter 15-21 μm) in the aqueous solution of sodium hydroxide for 3 h, the solid-liquid mass ratio of the bamboo fiber soaked in the aqueous solution of sodium hydroxide being 1:50; then solid-liquid separation, washing the solid phase with deionized water until the washing liquid is neutral, then drying at 80℃ for 8 h, obtaining alkali-washed bamboo fiber;

[0047] (2) configure the aqueous solution of ethanol, the volume percentage of ethanol in the aqueous solution of ethanol is 50%; adjust the pH of the aqueous solution of ethanol to 9 with 10wt% sodium hydroxide solution, then add the alkali washed bamboo fiber into the solution to prepare a suspension, the solid-liquid mass ratio of the alkali washed bamboo fiber added into the solution to prepare a suspension is 1:50; the suspension is water bathed in a nitrogen atmosphere to constant temperature at 60±2℃, after constant temperature, the suspension is stirred, and then vinyltriethoxysilane is added to the suspension under stirring, the mass ratio of the added vinyltriethoxysilane to the alkali washed bamboo fiber in the suspension is vinyltriethoxysilane: alkali washed bamboo fiber = 8:1; after the addition is completed, the suspension is continuously stirred at 60±2℃ in a nitrogen atmosphere for 2h, and then air-cooled to room temperature, solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 5h to obtain the first modified bamboo fiber;

[0048] (3) disperse the first modified bamboo fiber in toluene to form a toluene suspension, the solid-liquid mass ratio of the first modified bamboo fiber dispersed in toluene is solid / liquid = 1:50; the toluene suspension is water bathed in a nitrogen atmosphere to constant temperature at 80±3℃, the toluene suspension is stirred, then 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide are added to the toluene suspension under stirring, the mass ratio of the added 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the first modified bamboo fiber in the toluene suspension is 3-isopropyl-dimethyl benzyl isocyanate:dibenzoyl peroxide: first modified bamboo fiber = 4:0.3:1; after the addition is completed, the toluene suspension is continuously stirred at 80±3℃ in a nitrogen atmosphere for 15h, and then air-cooled to room temperature, solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 1h to obtain the second modified bamboo fiber;

[0049] (4) disperse the second modified bamboo fiber in dimethyl sulfoxide to form a dimethyl sulfoxide suspension, the solid-liquid mass ratio of the second modified bamboo fiber dispersed in dimethyl sulfoxide is solid / liquid = 1:50; the dimethyl sulfoxide suspension is water bathed to constant temperature at 60±3℃, then the dimethyl sulfoxide suspension is stirred, and then dimethylaminoethyl methacrylate and styrene are added to the suspension during stirring, after the addition is completed, the suspension is stirred at 60±3℃ for 10min, then azobisisobutyronitrile is added to the suspension under stirring, the mass ratio of the added dimethylaminoethyl methacrylate, styrene and azobisisobutyronitrile to the second modified bamboo fiber in the dimethyl sulfoxide suspension is dimethylaminoethyl methacrylate: styrene: azobisisobutyronitrile: second modified bamboo fiber = 3:3:0.1:1; after the addition is completed, the suspension is continuously stirred at 60±3℃ for 4h, and then solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 1h to obtain the modified bamboo fiber.

[0050] A resin-based composite material containing the modified bamboo fiber, the raw materials of the composite material including: epoxy resin, acetone, the modified bamboo fiber and ethylenediamine. The weight ratio of each raw material is: epoxy resin 100 parts, acetone 16 parts, the modified bamboo fiber 10 parts, and ethylenediamine 8 parts.

[0051] The preparation method of the resin-based composite material is as follows: each raw material is weighed according to the weight ratio, the epoxy resin and the acetone are mixed to form a mixture, the mixture is water-bathed and kept at 80°C, then the modified bamboo fiber is added to the mixture under stirring, after the addition, the mixture is kept at 80°C for 10 min, then the ethylenediamine is added, and the mixture is stirred at 80°C for 5 min, then poured into a mold, cooled, and cured at room temperature for 10 h to obtain the resin-based composite material.

[0052] Comparative Example 1

[0053] A modification method of a bamboo fiber for comparison, the steps including:

[0054] (1) An aqueous solution of sodium hydroxide is configured, the mass percentage of sodium hydroxide in the aqueous solution being 4%, and the solvent being water; the bamboo fiber (fiber length 3-6 cm, diameter 15-21 μm) is soaked in the aqueous solution of sodium hydroxide for 3 h, the solid-liquid mass ratio of the bamboo fiber in the aqueous solution of sodium hydroxide being 1:50; then the solid-liquid separation is performed, the solid phase is washed with deionized water until the liquid after washing is neutral, and then the solid phase is dried at 80°C for 8 h to obtain alkali-washed bamboo fiber;

[0055] (2) An aqueous solution of ethanol is configured, the volume percentage of ethanol in the aqueous solution being 50%; the pH of the aqueous solution of ethanol is adjusted to 9 with a 10 wt% sodium hydroxide solution, then the alkali-washed bamboo fiber is added to the solution to prepare a suspension, the solid-liquid mass ratio of the suspension being 1:50; the suspension is water-bathed and kept at 60±2°C in a nitrogen atmosphere, after the keeping, the suspension is stirred, then the vinyltriethoxysilane is added to the suspension under stirring, the mass ratio of the added vinyltriethoxysilane to the alkali-washed bamboo fiber in the suspension being vinyltriethoxysilane: alkali-washed bamboo fiber = 7:1; after the addition is completed, the suspension is kept and stirred at 60±2°C in the nitrogen atmosphere for 2 h, then air-cooled to room temperature, the solid-liquid separation is performed, the solid phase is washed with ethanol for 3 times, and then dried at 60°C for 5 h to obtain the first modified bamboo fiber;

[0056] (3) dispersing the primary modified bamboo fiber in dimethyl sulfoxide to form a dimethyl sulfoxide suspension, the solid-liquid mass ratio of the primary modified bamboo fiber dispersed in dimethyl sulfoxide being solid / liquid = 1:50; water-bath constant temperature of the dimethyl sulfoxide suspension to 60±3℃, then stirring the dimethyl sulfoxide suspension, adding dimethylaminoethyl methacrylate and styrene to the suspension during the stirring process, after the completion of the feeding, constant temperature of the suspension to 60±3℃ for 10 min, then adding azobisisobutyronitrile under the stirring state, the mass ratio of dimethylaminoethyl methacrylate, styrene and azobisisobutyronitrile to the primary modified bamboo fiber in the dimethyl sulfoxide suspension being dimethylaminoethyl methacrylate:styrene:azobisisobutyronitrile:primary modified bamboo fiber = 3:2:0.09:1; after the completion of the feeding, constant temperature of the suspension to 60±3℃ for 4 h, then solid-liquid separation, washing the solid phase with ethanol for 3 times, drying at 60℃ for 1 h, obtaining the modified bamboo fiber.

[0057] A resin-based composite material containing the modified bamboo fiber, the raw materials of the composite material including: epoxy resin, acetone, the modified bamboo fiber and ethylenediamine. The weight fractions of the raw materials are: epoxy resin 100 parts, acetone 14 parts, the modified bamboo fiber 8 parts and ethylenediamine 7 parts.

[0058] The preparation method of the resin-based composite material is: taking the raw materials according to the weight fractions, mixing the epoxy resin and acetone to form a mixture, water-bath constant temperature of the mixture to 80℃, then adding the modified bamboo fiber to the mixture under the stirring state, after the feeding, constant temperature of the mixture to 80℃ for 10 min, then adding the ethylenediamine, constant temperature of the mixture to 80℃ for 5 min, pouring into a mold to cool, curing at room temperature for 10 h, obtaining the resin-based composite material.

[0059] Comparative Example 2

[0060] A modification method of a bamboo fiber for comparison, the steps including:

[0061] (1) configuring an aqueous solution of sodium hydroxide, the mass percentage of sodium hydroxide in the aqueous solution of sodium hydroxide being 4%, and the solvent being water; soaking the bamboo fiber (fiber length 3-6 cm, diameter 15-21 μm) in the aqueous solution of sodium hydroxide for 3 h, the solid-liquid mass ratio of the bamboo fiber soaked in the aqueous solution of sodium hydroxide being 1:50; then solid-liquid separation, washing the solid phase with deionized water until the washing liquid is neutral, then drying at 80℃ for 8 h, obtaining the alkali-washed bamboo fiber;

[0062] (2) configure the aqueous solution of ethanol, the volume percentage of ethanol in the aqueous solution of ethanol is 50%; use 10wt% sodium hydroxide solution to adjust the pH of the aqueous solution of ethanol to 9, then add the alkali washed bamboo fiber into the solution to prepare a suspension, the solid-liquid mass ratio of the suspension prepared by adding the alkali washed bamboo fiber into the solution is 1:50; the suspension is water-bathed and kept at 60±2℃ in a nitrogen atmosphere, after keeping, the suspension is stirred, and vinyltriethoxysilane is added to the suspension under stirring, the mass ratio of the added vinyltriethoxysilane to the alkali washed bamboo fiber in the suspension is vinyltriethoxysilane: alkali washed bamboo fiber = 7:1; after the addition is completed, the suspension is kept at 60±2℃ in a nitrogen atmosphere and stirred for 2h, then air-cooled to room temperature, solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 5h to obtain the first modified bamboo fiber;

[0063] (3) disperse the first modified bamboo fiber in toluene to form a toluene suspension, the solid-liquid mass ratio of the first modified bamboo fiber dispersed in toluene is solid / liquid = 1:50; the toluene suspension is water-bathed and kept at 80±3℃ in a nitrogen atmosphere, the toluene suspension is stirred, then 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide are added to the toluene suspension under stirring, the mass ratio of the added 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the first modified bamboo fiber in the toluene suspension is 3-isopropyl-dimethyl benzyl isocyanate:dibenzoyl peroxide: first modified bamboo fiber = 4:0.3:1; after the addition is completed, the toluene suspension is stirred at 80±3℃ in a nitrogen atmosphere for 15h, and condensed reflux during keeping, then air-cooled to room temperature, solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 1h to obtain the second modified bamboo fiber;

[0064] (4) disperse the second modified bamboo fiber in dimethyl sulfoxide to form a dimethyl sulfoxide suspension, the solid-liquid mass ratio of the second modified bamboo fiber dispersed in dimethyl sulfoxide is solid / liquid = 1:50; the dimethyl sulfoxide suspension is water-bathed and kept at 60±3℃, then the dimethyl sulfoxide suspension is stirred, styrene is added to the suspension during stirring, after the addition is completed, the suspension is kept at 60±3℃ and stirred for 10min, then azobisisobutyronitrile is added to the suspension under stirring, the mass ratio of the added styrene and azobisisobutyronitrile to the second modified bamboo fiber in the dimethyl sulfoxide suspension is styrene: azobisisobutyronitrile: second modified bamboo fiber = 2:0.09:1; after the addition is completed, the suspension is kept at 60±3℃ and stirred for 4h, then solid-liquid separation, the solid phase is washed with ethanol for 3 times, and dried at 60℃ for 1h to obtain the modified bamboo fiber.

[0065] A resin-based composite material containing the modified bamboo fiber, the raw materials of the composite material including: epoxy resin, acetone, the modified bamboo fiber and ethylenediamine. The weight ratio of each raw material is: epoxy resin 100 parts, acetone 14 parts, the modified bamboo fiber 8 parts, and ethylenediamine 7 parts.

[0066] The preparation method of the resin-based composite material is as follows: each raw material is weighed according to the weight ratio, the epoxy resin and the acetone are mixed to form a mixture, the mixture is water-bathed and kept at 80°C, then the modified bamboo fiber is added to the mixture under stirring, after the addition, the mixture is kept at 80°C for 10 min, then the ethylenediamine is added, and the mixture is stirred at 80°C for 5 min, then poured into a mold and cooled, and cured at room temperature for 10 h to obtain the resin-based composite material.

[0067] Comparative Example 3

[0068] A modification method of a bamboo fiber for comparison, the steps including:

[0069] (1) An aqueous solution of sodium hydroxide is configured, the mass percentage of sodium hydroxide in the aqueous solution being 4%, and the solvent being water; the bamboo fiber (fiber length 3-6 cm, diameter 15-21 μm) is soaked in the aqueous solution of sodium hydroxide for 3 h, the solid-liquid mass ratio of the bamboo fiber in the aqueous solution of sodium hydroxide being 1:50; then the solid-liquid separation is performed, the solid phase is washed with deionized water until the liquid after washing is neutral, and then dried at 80°C for 8 h to obtain alkali-washed bamboo fiber;

[0070] (2) An aqueous solution of ethanol is configured, the volume percentage of ethanol in the aqueous solution being 50%; the pH of the aqueous solution of ethanol is adjusted to 9 with a 10 wt% sodium hydroxide solution, then the alkali-washed bamboo fiber is added to the solution to prepare a suspension, the solid-liquid mass ratio of the suspension being 1:50; the suspension is water-bathed and kept at 60±2°C in a nitrogen atmosphere, after keeping, the suspension is stirred, then the vinyltriethoxysilane is added to the suspension under stirring, the mass ratio of the added vinyltriethoxysilane to the alkali-washed bamboo fiber in the suspension being vinyltriethoxysilane: alkali-washed bamboo fiber = 7:1; after the addition is completed, the suspension is kept and stirred at 60±2°C in the nitrogen atmosphere for 2 h, then air-cooled to room temperature, the solid-liquid separation is performed, the solid phase is washed with ethanol for 3 times, and dried at 60°C for 5 h to obtain the first modified bamboo fiber;

[0071] (3) dispersing the primary modified bamboo fibers in toluene to form a toluene suspension, the solid-liquid mass ratio of the primary modified bamboo fibers dispersed in toluene being solid / liquid = 1:50; water-bath constant temperature of the toluene suspension to 80±3℃ in a nitrogen atmosphere, stirring the toluene suspension, then adding 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the toluene suspension in a stirring state, the mass ratio of 3-isopropyl-dimethyl benzyl isocyanate and dibenzoyl peroxide to the primary modified bamboo fibers in the toluene suspension being 3-isopropyl-dimethyl benzyl isocyanate:dibenzoyl peroxide:primary modified bamboo fibers = 4:0.3:1; after the completion of feeding, continuing to stir the toluene suspension at 80±3℃ in a nitrogen atmosphere for 15h, condensing reflux in the process of constant temperature, then air cooling to room temperature, solid-liquid separation, washing the solid phase with ethanol for 3 times, drying at 60℃ for 1h, obtaining secondary modified bamboo fibers;

[0072] (4) dispersing the secondary modified bamboo fibers in dimethyl sulfoxide to form a dimethyl sulfoxide suspension, the solid-liquid mass ratio of the secondary modified bamboo fibers dispersed in dimethyl sulfoxide being solid / liquid = 1:50; water-bath constant temperature of the dimethyl sulfoxide suspension to 60±3℃, then stirring the dimethyl sulfoxide suspension, adding dimethylaminoethyl methacrylate to the suspension in the process of stirring, after the completion of feeding, constant temperature stirring of the suspension at 60±3℃ for 10min, then adding azobisisobutyronitrile to the suspension in a stirring state, the mass ratio of dimethylaminoethyl methacrylate and azobisisobutyronitrile to the secondary modified bamboo fibers in the dimethyl sulfoxide suspension being dimethylaminoethyl methacrylate:azobisisobutyronitrile:secondary modified bamboo fibers = 3:0.09:1; after the completion of feeding, continuing to constant temperature stirring of the suspension at 60±3℃ for 4h, then solid-liquid separation, washing the solid phase with ethanol for 3 times, drying at 60℃ for 1h, obtaining modified bamboo fibers.

[0073] A resin-based composite material containing the modified bamboo fibers described above, the raw materials of the composite material including: epoxy resin, acetone, the modified bamboo fibers and ethylenediamine. The weight fractions of each raw material are: epoxy resin 100 parts, acetone 14 parts, the modified bamboo fibers 8 parts, ethylenediamine 7 parts.

[0074] The preparation method of the resin-based composite material described above is: taking each raw material according to the weight fractions described above, mixing the epoxy resin and acetone to form a mixture, water-bath constant temperature of the mixture to 80℃, then adding the modified bamboo fibers to the mixture in a stirring state, after feeding, continuing to constant temperature stirring of the mixture at 80℃ for 10min, then adding the ethylenediamine, constant temperature stirring at 80℃ for 5min, pouring into a mold to cool, curing at room temperature for 10h, obtaining the resin-based composite material.

[0075] Example 5

[0076] The tensile properties of the resin-based composite materials prepared by the method described in each of the above examples and comparative examples were tested according to the requirements of standard GB / T 1447-2005, the tensile speed was set to 5 mm / min, the sample was processed into a dumbbell-shaped sample with a gauge L0x end width b1x thickness d = 50 mm x 20 mm x 4 mm, five samples were tested for each group, and the average value was taken as the tensile strength result of the group, and the results are shown in Table 1. Figure 1

[0077] As can be seen from Figure 1 , the method according to the present application can significantly improve the mechanical properties of the composite material after the modification of the bamboo fiber and the addition of the epoxy resin, so that the epoxy resin matrix material can be applied to occasions with high stress demand, and the application range of the epoxy resin material is improved.

[0078] The above provides a detailed introduction to the technical solutions provided by the present application. For those skilled in the art, according to the idea of the embodiments of the present application, there will be changes in the specific implementation manner and application range. In summary, the content of the present application should not be understood as a limitation of the present application.​

Claims

1. A resin-based composite material made of modified bamboo fiber, characterized in that, The raw materials of the composite material are, by weight, 100 parts epoxy resin, 12-16 parts acetone, 5-10 parts modified bamboo fiber, and 6-8 parts ethylenediamine; the preparation steps of the modified bamboo fiber include: (1) Prepare an aqueous solution of sodium hydroxide, soak the bamboo fiber in the aqueous solution of sodium hydroxide for 3-4 hours, then separate the solid and liquid phases, wash the solid phase with deionized water until the washing liquid is neutral, and then dry it at 80°C for more than 8 hours to obtain alkali-washed bamboo fiber. (2) Prepare an aqueous solution of ethanol, adjust the pH of the aqueous solution of ethanol to 9 with 10wt% sodium hydroxide solution, and then add the alkaline-washed bamboo fiber to the solution to obtain a suspension. The suspension is kept at a constant temperature of 60±2℃ in a nitrogen atmosphere water bath. After the suspension is kept at a constant temperature, stir the suspension. Add vinyltriethoxysilane to the suspension while stirring. After the addition is completed, continue to keep the suspension at 60±2℃ in a nitrogen atmosphere and stir for more than 2 hours. Then air cool to room temperature, separate the solid and liquid, wash the solid phase with ethanol, and dry it at 60℃ for more than 5 hours to obtain primary modified bamboo fiber. (3) The primary modified bamboo fiber is dispersed in toluene to form a toluene suspension. The toluene suspension is kept at a constant temperature of 80±3℃ in a nitrogen atmosphere and stirred. Then, 3-isopropyl-dimethylbenzyl isocyanate and benzoyl peroxide are added to the toluene suspension while stirring. After the addition is completed, the toluene suspension is stirred in a nitrogen atmosphere at 80±3℃ for more than 15 hours. During the heat preservation process, the liquid is refluxed and then cooled to room temperature. The solid and liquid are separated. The solid phase is washed with ethanol more than 3 times and dried at 60℃ for more than 1 hour to obtain secondary modified bamboo fiber. (4) The modified bamboo fiber is dispersed in dimethyl sulfoxide to form a dimethyl sulfoxide suspension. The dimethyl sulfoxide suspension is kept at a constant temperature of 60±3℃ in a water bath. Then the dimethyl sulfoxide suspension is stirred. During the stirring process, dimethylaminoethyl methacrylate and styrene are added to the suspension. After the addition is completed, the suspension is stirred at a constant temperature of 60±3℃ for 10 to 20 minutes. Then azobisisobutyronitrile is added while stirring. After the addition is completed, the suspension is stirred at a constant temperature of 60±3℃ for more than 4 hours. Then the solid and liquid are separated. The solid phase is washed with ethanol more than 3 times and dried at 60℃ for more than 1 hour to obtain the modified bamboo fiber.

2. The modified bamboo fiber resin-based composite material according to claim 1, characterized in that, In step (1), the sodium hydroxide aqueous solution contains 3% to 5% sodium hydroxide by mass, and water is the solvent; the solid-liquid mass ratio of bamboo fiber soaked in the sodium hydroxide aqueous solution is 1:50 to 100.

3. The modified bamboo fiber resin-based composite material according to claim 1, characterized in that, In step (2), the volume percentage of ethanol in the aqueous solution of ethanol is 50% to 60%; the solid-liquid mass ratio of the suspension obtained by adding the alkali-washed bamboo fiber to the solution is 1:50; the mass ratio of the added vinyltriethoxysilane to the mass of the alkali-washed bamboo fiber in the suspension is vinyltriethoxysilane:alkali-washed bamboo fiber = 6 to 8:

1.

4. The modified bamboo fiber resin-based composite material according to claim 1, characterized in that, In step (3), the solid-liquid mass ratio of the primary modified bamboo fiber dispersed in toluene is solid / liquid = 1:50; the mass ratio of 3-isopropyl-dimethylbenzyl isocyanate and benzoyl peroxide to the mass ratio of the primary modified bamboo fiber in the toluene suspension is 3-isopropyl-dimethylbenzyl isocyanate: benzoyl peroxide: primary modified bamboo fiber = 3~4:0.2~0.3:

1.

5. The modified bamboo fiber resin-based composite material according to claim 1, characterized in that, In step (4), the solid-liquid mass ratio of the secondary modified bamboo fiber dispersed in dimethyl sulfoxide is solid / liquid = 1:50; the mass ratio of the added dimethylaminoethyl methacrylate, styrene, and azobisisobutyronitrile to the mass ratio of the secondary modified bamboo fiber in the dimethyl sulfoxide suspension is dimethylaminoethyl methacrylate: styrene: azobisisobutyronitrile: secondary modified bamboo fiber = 2~3:1~3:0.08~0.1:

1.

6. The method for preparing the resin-based composite material as described in claim 1, characterized in that, The steps are as follows: Weigh each raw material according to the stated weight proportions, mix the epoxy resin and acetone to form a mixture, keep the mixture at a constant temperature of 80°C in a water bath, then add the modified bamboo fiber to the mixture while stirring, continue stirring the mixture at a constant temperature of 80°C for 10-20 minutes after adding the material, then add the ethylenediamine, stir at a constant temperature of 80°C for 5-8 minutes, pour into a mold and cool, and cure at room temperature for more than 10 hours to obtain the resin-based composite material.

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