GB2594755A

GB2594755A - Method for preparing long bamboo fiber for molding composite

Info

Publication number: GB2594755A
Application number: GB2009878.6A
Authority: GB
Inventors: Zhang Wenfu; Wang Ge; Cheng Haitao; Zheng Haijun; Gu Shaohua
Original assignee: Zhejiang Academy of Forestry
Current assignee: Zhejiang Academy of Forestry
Priority date: 2020-05-09
Filing date: 2020-06-29
Publication date: 2021-11-10
Anticipated expiration: 2040-06-29
Also published as: GB2594755B; CN111394802A; GB202009878D0; CN111394802B

Abstract

A method for preparing a bamboo fibre for molding a composite, comprising a first step of preliminary treatment of the bamboo culm including harvesting, cutting into pieces of 6 mm thickness, a second step where rolling the cut pieces of bamboo by a three-stage roller. A third step comprises removing a vascular bundle of bamboo and grinding into a powder, fermenting the powder to obtain a fermented material that is added to saline and shaken, filtering and centrifuging the filtrate from the fermented material and saline to form a crude enzyme solution that is purified to obtain a biological enzyme. A fourth step comprises adding glucose to the enzyme, impregnating the rolled bamboo strip in the enzyme to treat the bamboo strip. The fifth step comprises washing the enzyme treated bamboo strip with water, and separating fibre bundles from the strip, the sixth step comprises flattening and drying the fibre bundles to obtain a fibre for molding a composite.

Description

METHOD FOR PREPARING LONG BAMBOO FIBER FOR MOLDING COMPOSITE TECHNICAL FIELD

The present invention belongs to the technical field of bamboo processing, and particularly relates to a method for preparing a long bamboo fiber for molding a composite. BACKGROUND The existing bamboo fiber preparation techniques mainly include roll splitting method, mechanical milling method, mechanical carding method, crack splitting method, explosion retting method, chemico-mechanical method and biological retting method. Among them, the first five methods are physio-mechanical methods, which obtain crude bamboo fibers through separation, while the latter two are physical-biochemical methods, which obtain fine bamboo fibers by separating the fibers from gums. The physio-mechanical methods and the biological retting method have the advantages of less environmental pollution, but have the disadvantages of long process time and poor fiber quality. The chemico-mechanical method has certain harm to the environment, but can obtain bamboo fibers with controllable quality. The bamboo fibers obtained by using a single preparation process have small size and large performance difference, so it is necessary to combine the methods to produce stable bamboo fibers.

SUMMARY

In order to overcome the deficiencies of the prior art, the present invention provides a method for preparing a long bamboo fiber for molding a composite. The long bamboo fiber for molding a composite prepared by this method features long length, small fineness, high tensile strength and high fracture resistance.

To solve the above technical problem, the present invention adopts the following technical solution: a method for preparing a long bamboo fiber for molding a composite, including the following steps.

St, preliminary treatment of bamboo culm: harvesting a fresh bamboo culm; cutting the bamboo culm, and removing a node to obtain a bamboo tube; cutting the bamboo tube into 4 to 8 pieces; removing yellow sides of the bamboo pieces, and remaining green sides thereof, to obtain bamboo pieces.

52, bamboo piece rolling: rolling the bamboo pieces obtained in SI in a forward direction by a three-stage smooth rolling device while rinsing the bamboo pieces with dean water to obtain a loose bamboo strip, where the rolling process includes: sequentially rolling the bamboo pieces by rollers with a clearance of 3.2 mm to 4.3 mm, 1.8 mm to 2.2 mm and 0.7 mm to 1 mm.

In the present invention, the three-stage smooth rolling device crushes the bamboo to form large gaps to increase the exposed area ofthe internal basic tissue of the bamboo, facilitating the impregnation with an enzyme in the later period and improving the contact surface between the enzyme and the bamboo.

S3, enzyme preparation: removing a vascular bundle of bamboo to obtain a basic tissue of the bamboo; grinding the basic tissue of the bamboo into a powder with a particle size of < 50 pm; adding the bamboo basic tissue powder and a strain to an extraction solution, and fermenting at 30-50°C for 24-28 h to obtain a fermented material; adding the fermented material to a physiological saline with a concentration of 0.05 mol/L, and shaking at room temperature for 1-2 h; filtering with a gauze, and centrifuging a filtrate at 4,000-5,000 r/min for 10-20 min; extracting a supernatant to obtain a crude enzyme solution; separating and purifying the crude enzyme solution to obtain a biological enzyme; mixing the biological enzyme, xylanase, pectinase and water thoroughly to obtain an enzyme, where the strain is Bacillus, Aspergillus niger or Aspergillus oryzae; the extraction solution is a citric acid-phosphate buffer, a sodium acetate buffer or a malonate buffer.

In the present invention, the biological enzyme is separated and purified from the basic tissue of the bamboo. The biological enzyme is suitable for enzymatic hydrolysis of the basic tissue of the bamboo, but the activity is low. The combination of the biological enzyme with the xylanase and the pectinase enhances the activity of the biological enzyme and promotes the effect of the biological enzyme to decompose the basic tissue of the bamboo.

S4, enzyme treatment of bamboo strip: adding glucose to the enzyme obtained in S3, and standing at room temperature for 2 h to activate the enzyme; impregnating the bamboo strip obtained in S2 in the activated enzyme at 25-35°C for 1.5-2 h; centrifuging at 1,500-2,500 r/min for 30 s, and standing for 1-30 min; centrifuging at 1,500-2,500 r/min for 30 s, and standing for 1 h; then taking out the bamboo strip to obtain an enzyme-treated bamboo strip.

S5, opening of bamboo strip: washing the enzyme-treated bamboo strip obtained in S4 with water, and draining; separating a long fiber bundle from the bamboo strip with an opener to obtain a bamboo fiber bundle preform with a length of 50-250 mm, where needle rollers and smooth rollers with opposite positions and opposite transmission directions are respectively provided on upper and lower surfaces of the opener; the needle rollers turn in a direction the same as a feeding direction.

S6, flattening and air-drying the bamboo fiber bundle preform obtained in S5 to obtain a long bamboo fiber for molding a composite.

Preferably, in Si, the bamboo pieces have a thickness of 4.5-6 mm and a moisture content of 70-80%.

Preferably, in S2, the bamboo strip has a weight loss rate of 15-25%, and a weight gain rate of 27-37% after absorbing water.

Preferably, in 53, the bamboo basic tissue powder, the strain and the extraction solution have a mass ratio of 1,000:(1-5):100.

Preferably, in S3, the biological enzyme, the xylanase, the pectinase and the water in the enzyme have a mass ratio of (3.5-4):(0.5-1):(0.5-1):1,000.

Preferably, in 53, the biological enzyme has a specific activity of 4,900-5,700 U/g, the xylanase has a specific activity of > 1.5 x 104 U/g, and the pectinase has a specific activity of > 3 x 103 U/g.

Preferably, in S4, the enzyme and the glucose have a mass ratio of 1:1.

Preferably, in S5, the needling rollers and the smooth rollers have a rotation speed of 1,200 rpm; the needling rollers have a needling density of 10 punches/cm2 and a needling length of 15 mm.

Preferably, in S6, the long bamboo fiber for molding a composite has a moisture content of 10-13%.

Compared with the prior art, the present invention has the following advantages: In the present invention, the bamboo is subjected to coordinated rolling, opening and enzyme treatment. The biological enzyme is separated and purified from the basic tissue of the bamboo. The biological enzyme is suitable for enzymatic hydrolysis of the basic tissue of the bamboo, but the activity is low. The combination of the biological enzyme with the xylanase and the pectinase enhances the activity of the biological enzyme and promotes the effect of the biological enzyme to decompose the basic tissue of the bamboo. By rolling, the basic tissues in the bamboo pieces are broken, thereby expanding the contact area between the enzyme and the basic tissues. The enzyme treatment promotes the decomposition of the basic tissues in the bamboo pieces, further weakening the binding between the basic tissues and the vascular bundles. Finally, the long bamboo fiber bundles with high tensile strength are separated by opening. In this way, the present invention removes the basic tissues (i.e. thin-walled tissues) between the fiber bundles while preventing excessive damage to the inside of the bamboo fiber bundles, thereby avoiding the separation of the long bamboo fibers for molding a composite into single fibers. The long bamboo fibers obtained by the present invention have a large length of 50-250 mm, a fineness of 31-74 utin, a large draw ratio, a high tensile strength, an average breaking force of up to 121 N and a high fracture resistance of 294 1\TPa.

The present invention is described in further detail below with reference to the examples. DETAILED DESCRIPTION

Example 1

This example provides a method for preparing a long bamboo fiber for molding a composite, including: Si, preliminary treatment of bamboo culm: harvest a fresh bamboo culm; cut the bamboo culm, and remove a node to obtain a bamboo tube; cut the bamboo tube into 4 to 8 pieces; remove yellow sides of the bamboo pieces, and remain green sides thereof, where the bamboo pieces have a thickness of 5 mm and a moisture content 70%.

S2, bamboo piece rolling: roll the bamboo pieces obtained in 51 in a forward direction by a three-stage smooth rolling device while rinsing the bamboo pieces with clean water to obtain a loose bamboo strip, where the rolling process includes: sequentially roll the bamboo pieces by rollers with a clearance of 3.5 mm, 2 mm and 0.8 mm, where the bamboo strip has a weight loss rate of 15%, and a weight gain rate of 27% after absorbing water.

53, enzyme preparation: remove a vascular bundle of bamboo to obtain a basic tissue of the bamboo; grind the basic tissue of the bamboo into a powder with a particle size of < 50 nm; add the bamboo basic tissue powder and a strain to an extraction solution, and ferment at 35°C for 26 h to obtain a fermented material; add the fermented material to a physiological saline with a concentration of 0.05 mol/L, and shake at room temperature for 1 h; filter with a gauze, and centrifuge a filtrate at 4,000 r/min for 10 min; extract a supernatant to obtain a crude enzyme solution; separate and purify the crude enzyme solution to obtain a biological enzyme; mix the biological enzyme, xylanase, pectinase and water thoroughly to obtain an enzyme, where the strain is Bacillus; the extraction solution is a citric acid-phosphate buffer; the bamboo basic tissue powder, the strain and the extraction solution have a mass ratio of 1,000:1:100; the biological enzyme, the xylanase, the pectinase and the water in the enzyme have a mass ratio of 3.5:0.5:0.5:1,000; the extraction solution is a citric acid-phosphate buffer; the biological enzyme has a specific activity of 5,700 U/g, the xylanase has a specific activity of > 1.5 >< to and the pectinase has a specific activity of > 3 >< 103 U/g.

54, enzyme treatment of bamboo strip: add glucose to the enzyme obtained in 53, and stand at room temperature for 2 h to activate the enzyme; impregnate the bamboo strip obtained in S2 in the activated enzyme at 25°C for 2 h; centrifuge at 1,500 r/min for 30 s, and stand for 30 min; centrifuge at 1,500 r/min for 30 s, and stand for 1 h; then take out the bamboo strip to obtain an enzyme-treated bamboo strip, where the enzyme and the glucose have a mass ratio of 1:1.

S5, opening of bamboo strip: wash the enzyme-treated bamboo strip obtained in S4 with water, and drain; separate a long fiber bundle from the bamboo strip with an opener to obtain a bamboo fiber bundle preform with a length of 50-250 mm, where needle rollers and smooth rollers with opposite positions and opposite transmission directions are respectively provided on upper and lower surfaces of the opener; the needle rollers turn in a direction the same as a feeding direction; the needling rollers and the smooth rollers have a rotation speed of 1,200 rpm; the needling rollers have a needling density of 10 punches/cm2 and a needling length of 15 mm.

56, flatten and air-dry the bamboo fiber bundle preform obtained in S5 to obtain bamboo fiber bundles with a moisture content of 10%; finally sort the bamboo fiber bundles by a mesh screen on a length basis to obtain three types of long bamboo fibers for molding a composite, which have a length of 50 mm < di < 100 mm, 100 mm < d2 < 150 mm and 150 mm < d3 < 250 mm, respectively.

In this example, the long bamboo fibers for molding a composite have the following properties: The 150 mm < d3 < 250 mm long bamboo fiber for molding a composite accounts for 20% of total fibers, and has an average fineness of 65 pm, an average breaking force of 103 N, an average tensile strength of 215 MPa and a tensile modulus of 19.2 GPa, The 100 mm < d2 < 150 mm long bamboo fiber for molding a composite accounts for 50% of total fibers, and has an average fineness of 43 pm, an average breaking force of 87 N, an average tensile strength of 272 MPa and a tensile modulus of 26.5 GPa, The 50 mm < di < 100 mm long bamboo fiber for molding a composite accounts for 30% of total fibers, and has an average fineness of 34 pm, an average breaking force of 66 N, an average tensile strength of 289 MPa and a tensile modulus of 29.1 GPa.

In this example, the bamboo is subjected to coordinated rolling, opening and enzyme treatment. The biological enzyme is separated and purified from the basic tissue of the bamboo. The biological enzyme is suitable for enzymatic hydrolysis of the basic tissue of the bamboo, but the activity is low. The combination of the biological enzyme with the xylanase and the pectinase enhances the activity of the biological enzyme and promotes the effect of the biological enzyme to decompose the basic tissue of the bamboo. By rolling, the basic tissues in the bamboo pieces are broken, thereby expanding the contact area between the enzyme and the basic tissues. The enzyme treatment promotes the decomposition of the basic tissues in the bamboo pieces, further weakening the binding between the basic tissues and the vascular bundles. Finally, the long bamboo fiber bundles with high tensile strength are separated by opening. In this way, this example removes the basic tissues (i.e. thin-walled tissues) between the fiber bundles while preventing excessive damage to the inside of the bamboo fiber bundles, thereby avoiding the separation of the long bamboo fibers for molding a composite into single fibers. The long bamboo fibers for molding a composite feature long length, small fineness, high tensile strength and high fracture resistance.

Example 2

This example provides a method for preparing a long bamboo fiber for molding a composite, including: St. preliminary treatment of bamboo culm: harvest a fresh bamboo culm; cut the bamboo culm, and remove a node to obtain a bamboo tube; cut the bamboo tube into 4 to 8 pieces; remove yellow sides of the bamboo pieces, and remain green sides thereof, where the bamboo pieces have a thickness of 6 mm and a moisture content 80%.

52, bamboo piece rolling: roll the bamboo pieces obtained in Si in a forward direction by a three-stage smooth rolling device while rinsing the bamboo pieces with clean water to obtain a loose bamboo strip, where the rolling process includes: sequentially roll the bamboo pieces by rollers with a clearance of 4.3 mm, 2.2 mm and 1 mm, where the bamboo strip has a weight loss rate of 20%, and a weight gain rate of 35% after absorbing water.

S3, enzyme preparation: remove a vascular bundle of bamboo to obtain a basic tissue of the bamboo; grind the basic tissue of the bamboo into a powder with a particle size of < 50 him; add the bamboo basic tissue powder and a strain to an extraction solution, and ferment at 50°C for 24 h to obtain a fermented material; add the fermented material to a physiological saline with a concentration of 0.05 mol/L, and shake at room temperature for 1.5 h; filter with a gauze, and centrifuge a filtrate at 5,000 r/min for 15 min; extract a supernatant to obtain a crude enzyme solution; separate and purify the crude enzyme solution to obtain a biological enzyme; mix the biological enzyme, xylanase, pectinase and water thoroughly to obtain an enzyme, where the strain is Aspergillus niger; the extraction solution is a sodium acetate buffer; the bamboo basic tissue powder, the strain and the extraction solution have a mass ratio of 1,000:3:100; the biological enzyme, the xylanase, the pectinase and the water in the enzyme have a mass ratio of 4:1:0,51,000; the extraction solution is a citric acid-phosphate buffer; the biological enzyme has a specific activity of 4,900 U/g, the xylanase has a specific activity of? 1.5 x 104 U/g, and the pectinase has a specific activity of > 3 x 103 U/g.

S4, enzyme treatment of bamboo strip: add glucose to the enzyme obtained in 53, and stand at room temperature for 2 h to activate the enzyme; impregnate the bamboo strip obtained in S2 in the activated enzyme at 35°C for 2 h; centrifuge at 2,000 r/min for 30 s, and stand for lmin; centrifuge at 2,000 r/min for 30 s, and stand for 1 h; then take out the bamboo strip to obtain an enzyme-treated bamboo strip, where the enzyme and the glucose have a mass ratio of 1:1.

S6, flatten and air-dry the bamboo fiber bundle preform obtained in S5 to obtain bamboo fiber bundles with a moisture content of 12%, finally sort the bamboo fiber bundles by a mesh screen on a length basis to obtain three types of long bamboo fibers for molding a composite, which have a length of 50 mm < di < 100 mm, 100 mm <d2 < 150 mm and 150 mm < (13 < 250 mm, respectively.

In this example, the long bamboo fibers for molding a composite have the following properties: The 150 mm < d3 < 250 mm long bamboo fiber for molding a composite accounts for 30% of total fibers, and has an average fineness of 68 pm, an average breaking force of 115 N, an average tensile strength of 223 MPa and a tensile modulus of 20.1 GPa.

The 100 mm < d2 < 150 mm long bamboo fiber for molding a composite accounts for 35% of total fibers, and has an average fineness of 47 p.m, an average breaking force of 92 N, an average tensile strength of 264 MPa and a tensile modulus of 25.8 GPa.

The 50 mm < di < 100 mm long bamboo fiber for molding a composite accounts for 35% of total fibers, and has an average fineness of 31 pm, an average breaking force of 59 N, an average tensile strength of 277 MPa and a tensile modulus of 28.3 GPa.

Example 3

This example provides a method for preparing a long bamboo fiber for molding a composite, including: St. preliminary treatment of bamboo culm: harvest a fresh bamboo culm; cut the bamboo culm, and remove a node to obtain a bamboo tube; cut the bamboo tube into 4 to 8 pieces; remove yellow sides of the bamboo pieces, and remain green sides thereof, where the bamboo pieces have a thickness of 4.5 mm and a moisture content 70%.

52, bamboo piece rolling: roll the bamboo pieces obtained in S1 in a forward direction by a three-stage smooth rolling device while rinsing the bamboo pieces with clean water to obtain a loose bamboo strip, where the rolling process includes: sequentially roll the bamboo pieces by rollers with a clearance of 3.2 mm, t.8 mm and 0.7 mm, where the bamboo strip has a weight loss rate of 25%, and a weight gain rate of 37% after absorbing water.

S3, enzyme preparation: remove a vascular bundle of bamboo to obtain a basic tissue of the bamboo; grind the basic tissue of the bamboo into a powder with a particle size of < 50 um; add the bamboo basic tissue powder and a strain to an extraction solution, and ferment at 30°C for 28 h to obtain a fermented material; add the fermented material to a physiological saline with a concentration of 0.05 mol/L, and shake at room temperature for 2 h; filter with a gauze, and centrifuge a filtrate at 4,500 r/min for 20 min; extract a supernatant to obtain a crude enzyme solution; separate and purify the crude enzyme solution to obtain a biological enzyme; mix the biological enzyme, xylanase, pectinase and water thoroughly to obtain an enzyme, where the strain is Aspergillus oryzae; the extraction solution is a malonate buffer; the bamboo basic tissue powder, the strain and the extraction solution have a mass ratio of 1,000:5 1 00; the biological enzyme, the xylanase, the pectinase and the water in the enzyme have a mass ratio of 4:0.5:1:1,000; the extraction solution is a citric acid-phosphate buffer; the biological enzyme has a specific activity of 4,900 U/g, the xylanase has a specific activity of > 1.5 x 104 U/g, and the pectinase has a specific activity of > 3 >< 10' U/g.

S4, enzyme treatment of bamboo strip: add glucose to the enzyme obtained in S3, and stand at room temperature for 2 h to activate the enzyme; impregnate the bamboo strip obtained in S2 in the activated enzyme at 25°C for 2 h; centrifuge at 2,500 r/min for 30 s, and stand for lmin; centrifuge at 2,500 r/min for 30 s, and stand for 1 h; then take out the bamboo strip to obtain an enzyme-treated bamboo strip, where the enzyme and the glucose have a mass ratio of 1:1 S5, opening of bamboo strip: wash the enzyme-treated bamboo strip obtained in S4 with water, and drain; separate a long fiber bundle from the bamboo strip with an opener to obtain a bamboo fiber bundle preform with a length of 50-250 mm, where needle rollers and smooth rollers with opposite positions and opposite transmission directions are respectively provided on upper and lower surfaces of the opener; the needle rollers turn in a direction the same as a feeding direction; the needling rollers and the smooth rollers have a rotation speed of 1,200 rpm; the needling rollers have a needling density of 10 punches/cm2 and a needling length of 15 mm.

S6, flatten and air-dry the bamboo fiber bundle preform obtained in S5 to obtain bamboo fiber bundles with a moisture content of 13%; finally sort the bamboo fiber bundles by a mesh screen on a length basis to obtain three types of long bamboo fibers for molding a composite, which have a length of 50 mm < di < 100 mm, 100 mm < d2 < 150 mm and 150 mm < d3 < 250 mm, respectively.

In this example, the long bamboo fibers for molding a composite have the following properties: The 150mm < d3 < 250mm long bamboo fiber for molding a composite accounts for 35% of total fibers, and has an average fineness of 74 pm, an average breaking force of 121 N, an average tensile strength of 226 MPa and a tensile modulus of 19.1 GPa, The 100 mm < d2 < 150 mm long bamboo fiber for molding a composite accounts for 45% of total fibers, and has an average fineness of 51 pm, an average breaking force of 97 N, an average tensile strength of 266 MPa and a tensile modulus of 25.8 GPa, The 50 mm < di < 100 mm long bamboo fiber for molding a composite accounts for 20% of total fibers, and has an average fineness of 39 pm, an average breaking force of 62 N, an average tensile strength of 294 MPa and a tensile modulus of 29.7 GPa.

The above described are merely preferred examples of the present invention, and are not intended to limit the present invention in any form. Any simple modifications, changes and equivalent variations made to the above examples according to the technical essence of the present invention should fall within the protection scope of the technical solutions of the present invention.

Claims

What is claimed is: I. A method for preparing a long bamboo fiber for molding a composite, wherein the method comprises: St. preliminary treatment of bamboo culm: harvesting a fresh bamboo culm; cutting the bamboo culm, and removing a node to obtain a bamboo tube; cutting the bamboo tube into 4 to 8 pieces; removing yellow sides of the bamboo pieces, and remaining green sides thereof, to obtain bamboo pieces; S2, bamboo piece rolling: rolling the bamboo pieces obtained in S1 in a forward direction by a three-stage smooth rolling device while rinsing the bamboo pieces with clean water to obtain a loose bamboo strip, wherein the rolling process comprises: sequentially rolling the bamboo pieces by rollers with a clearance of 3.2 mm to 4.3 mm, 1.8 mm to 2.2 mm and 0.7 mm to 1 mm; S3, enzyme preparation: removing a vascular bundle of bamboo to obtain a basic tissue of the bamboo; grinding the basic tissue of the bamboo into a powder with a particle size of < 50 pm; adding the bamboo basic tissue powder and a strain to an extraction solution, and fermenting at 30-50°C for 24-28 h to obtain a fermented material; adding the fermented material to a physiological saline with a concentration of 0.05 mol/L, and shaking at room temperature for 1-2 h; filtering with a gauze, and centrifuging a filtrate at 4,000-5,000 r/min for 10-20 min; extracting a supernatant to obtain a crude enzyme solution; separating and purifying the crude enzyme solution to obtain a biological enzyme; mixing the biological enzyme, xylanase, pectinase and water thoroughly to obtain an enzyme, wherein the strain is Bacillus, Aspergillus niger or Aspergillus oryzae; the extraction solution is a citric acid-phosphate buffer, a sodium acetate buffer or a malonate buffer; S4, enzyme treatment of bamboo strip: adding glucose to the enzyme obtained in S3, and standing at room temperature for 2 h to activate the enzyme; impregnating the bamboo strip obtained in S2 in the activated enzyme at 25-35°C for 1.5-2 h; centrifuging at 1,500-2,500 r/min for 30 s, and standing for 1-30 min; centrifuging at 1,500-2,500 r/min for 30 s, and standing for 1 h; then taking out the bamboo strip to obtain an enzyme-treated bamboo strip; S5, opening of bamboo strip: washing the enzyme-treated bamboo strip obtained in S4 with water, and draining; separating a long fiber bundle from the bamboo strip with an opener to obtain a bamboo fiber bundle preform with a length of 50-250 mm, wherein needle rollers and smooth rollers with opposite positions and opposite transmission directions are respectively provided on upper and lower surfaces of the opener; the needle rollers turn in a direction the same as a feeding direction; and S6, flattening and air-drying the bamboo fiber bundle preform obtained in S5 to obtain a long bamboo fiber for molding a composite.
2. The method for preparing a long bamboo fiber for molding a composite according to claim 1, wherein in Si, the bamboo pieces have a thickness of 4.5-6 mm and a moisture content of 70-80%.
3. The method for preparing a long bamboo fiber for molding a composite according to claim 1, wherein in S2, the bamboo strip has a weight loss rate of 15-25%, and a weight gain rate of 27-37% after absorbing water.
4. The method for preparing a long bamboo fiber for molding a composite according to claim 1, wherein in S3, the bamboo basic tissue powder, the strain and the extraction solution have a mass ratio of 1,000:(1-5):100.
5. The method for preparing a long bamboo fiber for molding a composite according to claim 1, wherein in 53, the biological enzyme, the xylanase, the pectinase and the water in the enzyme have a mass ratio of (3.5-4):(0.5-1):(0.5-1):1,000.
6. The method for preparing a long bamboo fiber for molding a composite according to claim 1 or 5, wherein in 53, the biological enzyme has a specific activity of 4,900-5,700 U/g, the xylanase has a specific activity of? 1.5 x 104 U/g, and the pectinase has a specific activity of > 3 x 103 U/g.
7. The method for preparing a long bamboo fiber for molding a composite according to claim 1, wherein in 54, the enzyme and the glucose have a mass ratio of 1:1.
8. The method for preparing a long bamboo fiber for molding a composite according to claim 1, wherein in 55, the needling rollers and the smooth rollers have a rotation speed of 1,200 rpm; the needling rollers have a needling density of 10 punches/cm2 and a needling length of 15 mm.
9. The method for preparing a long bamboo fiber for molding a composite according to claim 1, wherein in 56, the long bamboo fiber for molding a composite has a moisture content of 10-13%.