Bamboo fiber, preparation method thereof and bamboo fiber winding hydrogen storage tank

Abstract

This invention discloses a bamboo fiber, its preparation method, and a bamboo fiber wound hydrogen storage tank. The preparation method of the bamboo fiber includes the following steps: cutting natural bamboo into equal-length bamboo poles and pretreating them by soaking them in boiling water to remove water-soluble organic matter; mixing hydrogen peroxide, organic acid, and H2SO4 in a certain proportion to prepare a peroxyacid solution, wherein the concentration of hydrogen peroxide in the peroxyacid solution is 7-24 wt%, the concentration of organic acid is 15-55 wt%, and the concentration of H2SO4 is 0.5-3 wt%; soaking the pretreated bamboo poles in the peroxyacid solution at 50-60℃ for 12-20 hours to obtain bamboo fiber; then soaking the bamboo fiber in an alkaline solution for neutralization, and washing it after neutralization; vacuum drying the washed bamboo fiber and twisting it to extend its length to obtain long fiber; and applying microwave irradiation to the long fiber to obtain the final product.

Description

Technical Field

[0001] This invention belongs to the field of pressure vessel technology, specifically relating to a bamboo fiber, its preparation method, and a bamboo fiber wound hydrogen storage tank. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] High-pressure gaseous hydrogen storage boasts advantages such as simple equipment structure, low energy consumption for compression and maintenance, high hydrogen filling and discharging efficiency, and good adaptability to a wide temperature range, making it the most commonly used and mature hydrogen storage technology. Hydrogen storage tanks require high strength, high modulus, fatigue resistance, lightweight, explosion resistance, crushing resistance, and impact resistance for high safety performance. Currently, Type IV hydrogen storage tanks typically consist of three parts: an inner gas barrier layer, a middle pressure-resistant layer, and an outer protective layer. The middle pressure-resistant layer is the thickest and is usually made of epoxy resin composite material wound with carbon fiber. Carbon fiber, with its axially uniform arrangement and highly crystalline graphitized structure, is sufficient to meet the various performance requirements of the fibers wound around the hydrogen storage tank. However, the raw materials for preparing carbon fiber come from the petroleum cracking process, involving complex precursor fiber preparation processes such as monomer purification, polymerization, spinning, and drawing, as well as subsequent high-energy-consuming processes such as pre-oxidation, carbonization, and graphitization. The entire process has low resource utilization and significant environmental hazards.

[0004] China is rich in bamboo resources, and bamboo has a rapid growth cycle. Bamboo possesses highly efficient carbon sequestration capabilities throughout its growth process, from its initial development to becoming a bamboo product. Natural bamboo fiber maintains axial growth throughout, exhibiting high tensile strength and specific modulus of elasticity. Currently, bamboo raw fibers are typically obtained through a combination of mechanical physical splitting, chemical or biochemical degumming, and opening / carding. This process is lengthy and complex. While the finished fibers obtained through this method can partially retain the structure of natural bamboo fiber, their tensile strength and modulus of elasticity are significantly reduced, making it difficult to meet the mechanical performance requirements for fibers wound around hydrogen storage cylinders. Chemical methods typically hydrolyze bamboo chips into pulp, which is then spun to obtain regenerated cellulose bamboo pulp fiber. This hydrolysis and respinning process reshapes the bamboo cellulose structure, making it difficult to inherit the excellent mechanical properties of natural bamboo fiber. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide bamboo fiber, its preparation method, and a bamboo fiber wound hydrogen storage tank.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing bamboo fiber, comprising the following steps:

[0008] Natural bamboo is cut into equal-length bamboo poles and soaked in boiling water for pretreatment to remove water-soluble organic matter;

[0009] Hydrogen peroxide, organic acid, and H2SO4 are mixed in a certain proportion to prepare a peroxyacid solution. The concentration of hydrogen peroxide in the peroxyacid solution is 7-24 wt%, the concentration of organic acid is 15-55 wt%, and the concentration of H2SO4 is 0.5-3 wt%.

[0010] The pretreated bamboo poles are soaked in a peroxy acid solution at 50-60℃ for 12-20 hours to obtain bamboo fiber.

[0011] Then, the bamboo fiber is soaked in an alkaline solution for neutralization, and then washed.

[0012] After washing, the bamboo fibers are vacuum dried and twisted to extend their length, resulting in long fibers.

[0013] The long fibers are obtained by applying microwave irradiation.

[0014] The chemical composition of bamboo stems includes not only large amounts of cellulose, hemicellulose, and lignin, but also approximately 30% by mass of soluble pentosans and small amounts of other soluble organic matter. These soluble organic substances readily react with hydrogen peroxide, organic acids, and other substances, affecting the cellulose extraction process. Furthermore, bamboo with an unremoved soluble organic substance has a dense structure, which reduces the reaction efficiency of lignin removal and cellulose extraction. Therefore, pretreatment is necessary to remove water-soluble organic matter from the bamboo stems.

[0015] A small amount of H2SO4 serves as a catalyst for the reaction of hydrogen peroxide with organic acids to prepare peroxyacids; all three are indispensable. The hydroxyl (HO·) and superoxide anion (O2·-) radicals generated by peroxyacids attack the electron-rich aromatic rings and olefin side chains of lignin, leading to lignin depolymerization and dissolution. Hemicellulose, along with the depolymerization of lignin, breaks down and detaches from the bamboo fiber, leaving mostly cellulose. Therefore, peroxyacid solutions can selectively remove lignin and hemicellulose while retaining cellulose.

[0016] In some embodiments, the bamboo poles are soaked in boiling water for 1-2 hours.

[0017] In some embodiments, the organic acid is formic acid, acetic acid, oxalic acid, citric acid, malic acid, or maleic acid.

[0018] In some embodiments, the alkaline solution is NaOH solution, KOH solution, Na2CO3 solution, NaHCO3 solution, or ammonia water.

[0019] Preferably, the concentration of the alkaline solution is 0.5-3 wt%.

[0020] The neutralization time is 5-10 minutes, and the number of times deionized water is used for washing is >3.

[0021] In some embodiments, during the vacuum drying process, the vacuum degree is -0.06 to -0.1 MPa, and the drying time is 24-48 h.

[0022] In some embodiments, the microwave irradiation power is 100-240W, and the irradiation time is 30-60min. Through microwave irradiation, tight hydrogen bonds and van der Waals bonds are formed between the fibers within the fiber bundle, thereby obtaining bamboo fibers with high specific strength and specific modulus.

[0023] Preferably, during microwave irradiation, a stretching force is applied to both ends of the long fiber, with a stretching ratio of 4-7 times. The stretching ratio refers to the ratio of the fiber length to its original length after the stretching force is applied to both ends during microwave irradiation.

[0024] In some embodiments, each bundle of bamboo fibers contains 30-60 fibers, the twisting direction is S-twist, and the twist is 30-70 twists / 10cm.

[0025] Secondly, the present invention provides a bamboo fiber prepared by the aforementioned preparation method.

[0026] Thirdly, the present invention provides a bamboo fiber wound hydrogen storage tank, which consists of an inner liner, a bamboo fiber wound layer and an outer protective layer from the inside out, wherein the bamboo fiber wound layer is a composite material of bamboo fiber and epoxy resin.

[0027] In some embodiments, the inner liner is made of high-density polyethylene (HDPE), polyamide (PA6), polyethylene terephthalate (PET), or polyether-based material.

[0028] Preferably, the thickness of the inner liner is 2-4mm.

[0029] In some embodiments, the thickness of the bamboo fiber winding layer is 20-30 mm.

[0030] In some embodiments, the outer protective layer is a glass fiber reinforced epoxy resin composite material.

[0031] Preferably, the glass fiber is S-type glass fiber or E-type glass fiber.

[0032] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0033] This invention provides a bamboo fiber wound hydrogen storage tank. A chemical-microwave method is used to selectively remove lignin and hemicellulose from the bamboo structure while largely preserving the cellulose arrangement in natural bamboo. Leveraging the high specific strength, high specific modulus, fatigue resistance, and long service life of natural bamboo fiber, this invention enables the preparation of a bamboo fiber wound hydrogen storage tank. The method proposed in this invention is efficient, environmentally friendly, and low in energy consumption, representing a viable alternative to current carbon fiber hydrogen storage tank manufacturing methods. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0035] Figure 1 This is a flowchart illustrating the preparation process of the bamboo fiber hydrogen storage tank provided in this embodiment of the invention.

[0036] Figure 2 This is a cross-sectional front view of the bamboo fiber hydrogen storage tank provided in an embodiment of the present invention. Detailed Implementation

[0037] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] Example 1

[0040] The preparation method of high-strength bamboo natural fiber includes the following steps:

[0041] (1) Cut natural bamboo into equal-length bamboo poles and soak them in boiling water for 1 hour.

[0042] (2) Mix 30wt% hydrogen peroxide and >98wt% formic acid in a volume ratio of 5:5, and then add 99wt% H2SO4 solution until the mass concentration of H2SO4 in the mixed solution reaches 1wt%.

[0043] (3) Soak the bamboo poles treated in step (1) in the highly selective peroxy acid solution prepared in step (2) and heat at 50°C for 12 hours.

[0044] (4) Take out the natural bamboo fiber obtained in step (3), soak it in a 1 wt% NaOH solution, and then wash it three times in deionized water.

[0045] (5) Place the bamboo fiber obtained in step (4) into a vacuum dryer, adjust the vacuum degree to -0.1 MPa, and dry for 48 hours.

[0046] (6) Select 30 bamboo fibers from step (5) as a bundle, and twist the bundle of fibers in the S-twist direction with a twist of 50 twists / 10cm.

[0047] (7) Transfer the long fiber from step (5) to a microwave oven, apply a stretching force of 5 times to both ends of the long fiber, set the power range of the microwave oven to 150W, and microwave irradiate for 45 minutes.

[0048] The method for preparing a bamboo fiber wound hydrogen storage tank is as follows:

[0049] The manufacturing process and material standards for the inner liner and outer protective layer are the same as those for carbon fiber wound hydrogen storage cylinders. Relevant material parameters in the example are as follows: the inner liner is approximately 3mm thick and made of high-density polyethylene (HDPE); the bamboo fiber winding layer is composed of bamboo fiber and epoxy resin composite material, with a thickness of approximately 25mm; the glass fiber protective layer is approximately 3mm thick, using S-shaped glass fiber. The bamboo fiber is impregnated with epoxy resin in an impregnation device, and then directly wound onto the inner liner of the hydrogen storage tank using tension guide rollers at a conveying speed of 10cm / s and a tension of 300N / m.

[0050] During the winding process, the inner cylinder is first wound circumferentially, with a fiber winding angle typically between 85-90°, until the cylinder is fully covered with bamboo fiber, reaching a winding thickness of approximately 10mm. Then, the cylinder and end caps are spirally wound, with a winding angle of approximately 12-70°, resulting in a winding thickness of approximately 15mm. Finally, the wound bamboo fiber hydrogen storage tank is cured at a curing temperature of 150℃ for 3 hours.

[0051] Example 2

[0052] A bamboo fiber wound hydrogen storage tank, referring to the method of Example 1, except that the vacuum degree of the vacuum dryer in step (5) of Example 1 is adjusted to -0.06MPa and dried for 24h.

[0053] Example 3

[0054] A bamboo fiber wound hydrogen storage tank, referring to the method of Example 1, except that the twisting degree of step (6) of Example 1 is adjusted to 30 twists / 10cm.

[0055] Example 4

[0056] A bamboo fiber wound hydrogen storage tank, referring to the method of Example 1, except that the stretching ratio of step (7) of Example 1 is adjusted to 7 times.

[0057] Comparative Example 1

[0058] A bamboo fiber wound hydrogen storage tank is prepared by drying in a cool place in step (5) of Example 1, and then twisting in step (6) of Example 1.

[0059] Comparative Example 2

[0060] A bamboo fiber wound hydrogen storage tank is prepared by soaking-peeling method: bamboo strips are soaked in water for about three days, then bamboo fiber bundles are peeled off from the bamboo strips, dried in a cool place, and twisted in step (6) of Example 1.

[0061] Comparative Example 3

[0062] A bamboo fiber wound hydrogen storage tank, wherein the bamboo fiber preparation process is as follows:

[0063] 1. Bamboo pulp preparation: Crush bamboo, then mix it with a salt solution (25wt% NaOH solution: 25wt% Na2S solution = 1:4, volume ratio), and cook at 160℃ for 2 hours, then keep warm for 2 hours.

[0064] 2. Preparation of adhesive solution: Add carbon disulfide to the cooked bamboo powder at a solid-liquid ratio of 1:3, treat the pulp at room temperature for 2 hours, then add sodium hydroxide until the sodium hydroxide in the mixture reaches 23 wt%, and age for 2 hours to prepare the adhesive solution.

[0065] 3. Spinning: The viscose solution was added to the solution tank, and wet spinning was carried out under a pressure of 0.3 MPa. The filament aperture was 50 μm, the spinning temperature was 70℃, the nozzle draw ratio was 0.5, and 25℃ deionized water was used as the coagulation bath. The fibers were then air-dried at room temperature to produce bamboo pulp fibers. The bamboo pulp fibers were then twisted in step (6) of Example 1 to obtain the final product.

[0066] Comparative Example 4

[0067] A carbon fiber wound hydrogen storage tank, the same as the carbon fiber wound hydrogen storage tank in Example 1.

[0068] Table 1 Mechanical properties of bamboo fiber wound hydrogen storage tanks

[0069]

[0070] Implementation results:

[0071] As can be seen from Examples 1-4 and Comparative Examples 1-4, the bamboo fiber wound hydrogen storage tank of the present invention can significantly improve the mechanical properties of the hydrogen storage tank. A comparison of Example 1 and Comparative Example 1 shows that vacuum drying and microwave irradiation treatment of drawn bamboo fibers are important means to improve their mechanical properties. A comparison of Comparative Example 1 with Comparative Examples 2 and 3 shows that the chemical-microwave method proposed in this invention achieves selective removal of lignin and hemicellulose from the bamboo structure while largely preserving the cellulose arrangement structure in natural bamboo, thereby obtaining natural bamboo fibers with high tensile strength. A comparison of Examples 1-4 and Comparative Example 4 reveals that the mechanical properties of the bamboo fiber wound hydrogen storage tank proposed in this invention still have a small gap compared to the carbon fiber hydrogen storage tank. However, the method proposed in this invention is efficient, green, and low in energy consumption, making it an effective alternative for the preparation of carbon fiber hydrogen storage tanks.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing bamboo fiber, characterized in that: Includes the following steps: Natural bamboo is cut into equal-length bamboo poles and soaked in boiling water for pretreatment to remove water-soluble organic matter; Hydrogen peroxide, organic acid, and H2SO4 are mixed in a certain proportion to prepare a peroxyacid solution. In the peroxyacid solution, the concentration of hydrogen peroxide is 7-24 wt%, the concentration of organic acid is 15-55 wt%, and the concentration of H2SO4 is 0.5-3 wt%. The pretreated bamboo poles are soaked in a peroxy acid solution at 50-60℃ for 12-20 hours to obtain bamboo fiber. Then, the bamboo fiber is soaked in an alkaline solution for neutralization, and then washed. After washing, the bamboo fibers are vacuum dried at a vacuum level of -0.06 to -0.1 MPa, and then twisted to extend their length, resulting in long fibers. Each bundle of bamboo fibers contains 30-60 fibers, twisted in an S-twist direction, and with a twist of 30-70 twists / 10cm. The long fibers are irradiated with microwaves at a power of 100-240W for 30-60 minutes. During the irradiation process, a stretching force is applied to both ends of the long fibers, with a stretching ratio of 4-7 times. The bamboo fiber obtained by the preparation method is used to prepare bamboo fiber wound hydrogen storage tanks.

2. The method for preparing bamboo fiber according to claim 1, characterized in that: The bamboo poles should be soaked in boiling water for 1-2 hours.

3. The method for preparing bamboo fiber according to claim 1, characterized in that: The organic acid is formic acid, acetic acid, oxalic acid, citric acid, malic acid, or maleic acid.

4. The method for preparing bamboo fiber according to claim 1, characterized in that: The alkaline solution is NaOH solution, KOH solution, Na2CO3 solution, NaHCO3 solution, or ammonia water.

5. The method for preparing bamboo fiber according to claim 4, characterized in that: The concentration of the NaOH solution is 0.5-3 wt%.

6. The method for preparing bamboo fiber according to claim 1, characterized in that: During vacuum drying, the drying time is 24-48 hours.

7. A type of bamboo fiber, characterized in that: It is prepared by any one of the preparation methods described in claims 1-6.

8. A bamboo fiber wound hydrogen storage tank, characterized in that: From the inside out, the layers are an inner liner, a bamboo fiber winding layer, and an outer protective layer. The bamboo fiber winding layer is a composite material of bamboo fiber and epoxy resin as described in claim 7.

9. The bamboo fiber wound hydrogen storage tank according to claim 8, characterized in that: The inner liner is made of high-density polyethylene, polyamide, polyethylene terephthalate, or polyether-based material.

10. The bamboo fiber wound hydrogen storage tank according to claim 8, characterized in that: The thickness of the inner liner is 2-4mm.

11. The bamboo fiber wound hydrogen storage tank according to claim 8, characterized in that: The thickness of the bamboo fiber winding layer is 20-30mm.

12. The bamboo fiber wound hydrogen storage tank according to claim 8, characterized in that: The outer protective layer is a glass fiber reinforced epoxy resin composite material.

13. The bamboo fiber wound hydrogen storage tank according to claim 12, characterized in that: The glass fiber is either S-type or E-type glass fiber.

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