Preparation method of lightweight and degradable nanocellulose / bamboo fiber thermal insulation material

Abstract

The invention discloses a method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material, the method comprising: removing green, yellow and bamboo nodes from bamboo, splitting bamboo strips vertically, and obtaining bamboo staple fibers by a chemical separation method; mixing bamboo staple fibers with a 1,4-butanediol aqueous solution, heating and stirring, filtering to obtain expanded bamboo staple fibers; mixing expanded bamboo staple fibers with a dodecyltrimethylammonium bromide solution, adjusting the pH to 11, sealing and shaking in a water bath environment, washing to neutrality, and obtaining modified bamboo staple fibers; mixing the modified bamboo staple fibers with a nanocellulose solution, heating and stirring to obtain a solid-liquid mixture; pouring the solid-liquid mixture into a mold, and performing a high-temperature short-time thermoforming process to obtain a nanocellulose / bamboo fiber thermal insulation material. The nanocellulose / bamboo fiber thermal insulation material prepared by the present invention has the performance of light weight, high strength and good thermal insulation performance.

Description

Technical Field

[0001] The invention belongs to the technical field of bamboo material processing and utilization, and particularly relates to a method for preparing a lightweight and degradable nano-cellulose / bamboo fiber thermal insulation material. Background Art

[0002] Lightweight thermal insulation materials are widely used in the fields of construction, home furnishing, transportation, packaging, etc., and the thermal insulation performance of ultra-low density thermal insulation materials mainly depends on the thermal conductivity of the material. In order to obtain a lower thermal conductivity. At present, lightweight thermal insulation materials are mainly based on petroleum-based foam materials to obtain thermal insulation materials with low thermal conductivity and light weight. Most commonly used thermal insulation materials are foamed polyurethane (PU), extruded polystyrene (XPS), phenolic resin insulation board (PIB), expanded polystyrene (EPS), glass fiber, aerogel and rock wool. Due to the limitation of raw materials, lightweight foam plastics are as difficult to degrade as ordinary plastics. They cannot be naturally degraded after use and scrapping, forming white pollution.

[0003] Aiming at the problem that the products made of foaming materials are difficult to degrade due to the limitation of their raw materials, a method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material is proposed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material in view of the shortcomings of the above-mentioned prior art. The method is based on bamboo fiber puffing technology, and utilizes the characteristics of bamboo fiber that it is easy to absorb small molecular materials after expansion to improve the adsorption capacity of bamboo fiber for nanocellulose and obtain better binding performance; then, bamboo fiber reinforcement technology is used to improve the fusion degree of bamboo fiber mechanical strength and nanocellulose, and after high temperature and short time thermoforming, a degradable biomass nanocellulose / thermal insulation bamboo fiber material is made.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material, the method comprising:

[0006] S1. Prefabrication of bamboo staple fibers: After removing green, yellow and bamboo nodes from bamboo, splitting the bamboo strips vertically, placing the bamboo strips in a mixed solution and stirring to mix, then heating the mixed solution in a water bath, washing the mixed solution in running water until neutral, placing the mixed solution in warm water, stirring and sieving the mixed solution, and obtaining bamboo staple fibers;

[0007] S2, bamboo fiber puffing: the bamboo short fibers obtained in S1 and a 1,4-butanediol aqueous solution with a mass fraction of 3-5% are mixed evenly, the mixture is heated to 90-95° C., stirred evenly, and then allowed to stand for 40-60 minutes, and filtered through a sieve to obtain puffed bamboo short fibers;

[0008] S3, bamboo fiber reinforcement: after the expanded bamboo staple fibers obtained in S2 and the dodecyl trimethyl ammonium bromide solution with a mass fraction of 0.05-0.10% are mixed evenly, the pH value is adjusted to 11 with NaOH powder and then sealed, and then ultrasonically vibrated in a water bath environment, and then washed with distilled water until neutral to obtain modified bamboo staple fibers; the modified bamboo staple fibers are mixed evenly with the nanocellulose solution, and stirred at a temperature of 25-30° C. for 10-30 minutes to obtain a solid-liquid mixture;

[0009] S4, high temperature short time thermoforming: pour the solid-liquid mixture obtained in S3 into a mold, and perform high temperature short time thermoforming treatment to obtain the nanocellulose / bamboo fiber thermal insulation material.

[0010] Preferably, the bamboo in S1 is 6-year-old bamboo; the length and width of the bamboo strips are 50×10 mm; the temperature of the water bath heating is 60° C. and the time is 14 hours.

[0011] Preferably, the solid-liquid ratio of the bamboo strips and the mixed solution in S1 is 1:1; the mixed solution is made of 30% by volume hydrogen peroxide and glacial acetic acid, and the volume ratio of 30% by volume hydrogen peroxide and glacial acetic acid in the mixed solution is 1:1.

[0012] Preferably, the flow rate of the water in S1 is 0.6 m / s, the temperature is 25-40° C., and the stirring and mixing time is 3 min.

[0013] Preferably, the temperature of the warm water in S1 is 25-40° C.; the mesh size of the sieve used for screening is 200 meshes; and the aspect ratio of the bamboo staple fibers is in the range of 60-90.

[0014] Preferably, the solid-to-liquid ratio of the bamboo staple fibers in S2 to the 1,4-butanediol aqueous solution with a mass fraction of 3 to 5% is 1:2.

[0015] Preferably, the mesh size of the sieve in S2 is 200 meshes.

[0016] Preferably, in S3, the solid-to-liquid ratio of the puffed bamboo staple fibers to the dodecyltrimethylammonium bromide solution with a mass fraction of 0.05-0.10% is 1:30; the temperature of the water bath environment is 60° C., and the ultrasonic oscillation time is 1 hour.

[0017] Preferably, the nanocellulose solution in S3 is made of water and nanocellulose, and the mass fraction of nanocellulose in the nanocellulose solution is 3-5%; the solid-liquid ratio of the modified bamboo staple fibers to the nanocellulose solution is 1:5.

[0018] Preferably, the high temperature short time hot forming treatment in S4 is performed at a temperature of 190-200° C. and a time of 3-5 min / mm.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention is based on the bamboo short fibers after chemical separation. In order to reduce the density of the bamboo short fibers, they are subjected to puffing treatment. In order to improve the mechanical properties of the fibers, they are subjected to cationization pretreatment. The characteristics of nanocellulose containing negative hydroxyl groups and the small volume are utilized to make the combination of the two more firm. A composite bamboo fiber thermal insulation material with light weight, high strength and good thermal insulation performance is made by a high-temperature short-time thermoforming method.

[0021] 2. The bamboo fiber puffing technology of the present invention adopts a cosolvent (1,4-butanediol aqueous solution) to make the wood fiber swell, that is, the puffing agent and water molecules dissolve into a mixture. After the mixture molecules diffuse into the pores between the fibers, the distance between the amorphous molecules of the fibers is expanded, which plays a role in puffing the fibers. The increase in the internal voids of the fibers is conducive to nanocellulose filling the gaps between the fibers, making the bonding strength between the two fibers better.

[0022] 3. The bamboo fiber reinforcement technology of the present invention combines nanocellulose with expanded bamboo short fibers; the main structure of nanocellulose is composed of β-d-glucose monomers connected by 1,4-β-glycosidic bonds, which not only has the morphological structure and performance of cellulose fibers, but also has excellent properties of nanomaterials such as high surface area, high adsorption capacity, and easy surface functionalization. At the same time, as an environmentally friendly polymer material rich in negative hydroxyl groups, nanocellulose can be closely interwoven with bamboo fibers by increasing fiber bonding points to enhance the inter-fiber force and form a strong bond between fibers.

[0023] At the same time, dodecyltrimethylammonium bromide (DTAB) is a cationic ion. It is hydrated under alkaline conditions and is adsorbed by the cellulose in the fibers during the process. It combines with the negative hydroxyl groups in the nanocellulose through Coulomb attraction to form ion pairs. In this process, the nanocellulose fills the pores between the fibers while linking the gaps between the fiber bundles, so that the fibers can be bonded while being reinforced, forming a material with light weight, high strength, more porosity and lower thermal conductivity.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an electron microscope image of the bamboo fiber after being processed by bamboo short fiber prefabrication, bamboo fiber expansion and bamboo fiber reinforcement in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] Example 1

[0027] The preparation method of the lightweight and degradable nanocellulose / bamboo fiber thermal insulation material of this embodiment is as follows:

[0028] S1. Prefabrication of bamboo staple fibers: After removing green, yellow and bamboo nodes from 6-year-old bamboo, split the bamboo strips vertically into strips with a length and width of 50×10 mm, put the strips into a mixed solution and stir at a rate of 60 r / min for 3 min, then heat in a water bath at a temperature of 60° C. for 14 h until the strips turn white and become soft, then wash them with running water at a flow rate of 0.6 m / s and a temperature of 25° C. until they become neutral, then put them into warm water at a temperature of 25° C., stir at a rate of 120 r / min, and sieve them with a sieve with a mesh number of 200 to obtain bamboo staple fibers with an aspect ratio of 60 to 90;

[0029] The solid-liquid ratio of the bamboo strips to the mixed solution is 1:1; the mixed solution is made of 30% by volume hydrogen peroxide and glacial acetic acid, and the volume of 30% by volume hydrogen peroxide and glacial acetic acid in the mixed solution is 1:1;

[0030] After the bamboo strips are chemically treated in this step, bamboo short fibers with a small aspect ratio (60-90) are separated, which can be evenly dispersed in water to form a suspended liquid, and can be evenly mixed with an additive (1,4-butanediol aqueous solution); at the same time, most of the lignin and hemicellulose, as well as a small amount of cellulose, are removed during the preparation process, so the quality of the bamboo short fibers will also be reduced, which can further reduce the density of the manufactured material;

[0031] S2, bamboo fiber puffing: the bamboo short fibers obtained in S1 and a 3% by mass 1,4-butanediol aqueous solution were mixed evenly, the mixture was heated to 90° C., stirred evenly, and then allowed to stand for 40 minutes, and filtered through a 200-mesh sieve to obtain puffed bamboo short fibers;

[0032] The solid-to-liquid ratio of the bamboo staple fibers to the 3% by mass 1,4-butanediol aqueous solution is 1:2; since the bamboo staple fibers chemically treated in step S1 will shrink, their volume will decrease, and their density will increase, the bamboo staple fibers need to be puffed and modified to increase their mass and reduce their density, so that the density of the manufactured material is reduced, the gaps between the fibers are increased, and the degree of adhesion with the nanocellulose is enhanced;

[0033] S3, bamboo fiber reinforcement: the expanded bamboo staple fibers obtained in S2 and a 0.05% by mass dodecyltrimethylammonium bromide (DTAB) solution were mixed evenly, the pH value was adjusted to 11 with NaOH powder and then sealed, and then ultrasonically vibrated for 1 hour in a water bath at a temperature of 60° C., and then washed with distilled water until neutral to obtain modified bamboo staple fibers; the modified bamboo staple fibers were mixed with a 3% by mass nanocellulose solution, and stirred at a rate of 60 r / min for 30 minutes at a temperature of 25° C. to obtain a solid-liquid mixture;

[0034] The solid-liquid ratio of the puffed bamboo staple fiber to the dodecyl trimethyl ammonium bromide solution with a mass fraction of 0.05% to 0.10% is 1:30; the solid-liquid ratio of the modified bamboo staple fiber to the nanocellulose solution with a mass fraction of 3% is 1:5; after puffing, the bamboo staple fiber becomes soft and its strength decreases, so it is necessary to enhance the strength of the puffed bamboo staple fiber, and by utilizing the negative hydroxyl group of nanocellulose, the puffed bamboo staple fiber is endowed with positive characteristics under alkaline conditions, so that the nanocellulose and the puffed bamboo staple fiber can be better combined, and the function is to fill the gaps between the fibers, bond the gaps between the fibers, and bond the gaps between the fiber bundles, so as to strengthen the fibers and link the fibers to form a combination;

[0035] S4, high temperature short time thermoforming: pour the solid-liquid mixture obtained in S3 into a mold, and perform high temperature short time thermoforming treatment at a temperature of 190°C and a time of 3 min / mm to obtain a nanocellulose / bamboo fiber thermal insulation material; the high temperature short time thermoforming treatment has higher production efficiency, and the porosity of the nanocellulose / bamboo fiber thermal insulation material is increased, the thermal conductivity is reduced, and the thermal insulation performance is improved.

[0036] The nanocellulose / bamboo fiber thermal insulation material prepared in this embodiment can be used as an indoor wall thermal insulation material. The density of the nanocellulose / bamboo fiber thermal insulation material prepared in this embodiment is 0.120 g / cm 3 ; Thermal conductivity is 0.055W / mk; Degradation rate is 95.6%; Compressive strength is 0.4MPa.

[0037] Depend on Figure 1It can be seen that the bamboo staple fibers obtained after chemical treatment of bamboo strips shrink and become smaller in volume; after bamboo staple fibers are puffed, they become soft and their strength decreases; therefore, through bamboo fiber reinforcement treatment, the characteristics of nanocellulose containing negative hydroxyl groups are utilized to give the puffed bamboo staple fibers positive characteristics under alkaline conditions, so that nanocellulose and puffed bamboo staple fibers can be better combined, and their function is to fill the gaps between fibers, bond the gaps between fibers, and bond the gaps between fiber bundles, thereby strengthening the fibers while linking the fibers to form a combination.

[0038] Comparative Example 1

[0039] The preparation method of the nanocellulose / bamboo fiber thermal insulation material in this comparative example is exactly the same as that in Example 1, the difference is that S2 and bamboo fiber puffing treatment are not performed in the preparation method of this comparative example;

[0040] The density of the nanocellulose / bamboo fiber thermal insulation material prepared in this comparative example is 0.124 g / cm 3 ; Thermal conductivity is 0.065W / mk; Degradation rate is 95.5%; Compressive strength is 0.35MPa.

[0041] Comparative Example 2

[0042] The preparation method of the nanocellulose / bamboo fiber thermal insulation material in this comparative example is exactly the same as that in Example 1, the difference is that the preparation method of this comparative example does not perform S2, bamboo fiber puffing and S3 bamboo fiber reinforcement treatment;

[0043] The density of the bamboo fiber thermal insulation material prepared in this comparative example is 0.129 g / cm 3 ; Thermal conductivity is 0.69W / mk; Degradation rate is 95.1%; Compressive strength is 0.29MPa.

[0044] In summary, compared with the nanocellulose / bamboo fiber thermal insulation material prepared in Example 1 without bamboo fiber expansion treatment, the density and thermal conductivity of the nanocellulose / bamboo fiber thermal insulation material prepared in Example 1 increased, and the degradation rate and compressive strength decreased. Compared with the nanocellulose / bamboo fiber thermal insulation material prepared in Example 1 without bamboo fiber expansion and bamboo fiber reinforcement treatment, the density of the bamboo fiber thermal insulation material prepared in Example 2 increased by 0.009 g / cm 3 , the thermal conductivity increased by 0.635W / mk, the degradation rate decreased by 0.5%, and the compressive strength decreased by 0.11MPa. It can be seen that the nanocellulose / bamboo fiber insulation material prepared by the joint treatment of bamboo fiber expansion and bamboo fiber reinforcement has the best degradation rate, thermal conductivity, density and compressive strength.

[0045] Example 2

[0046] The preparation method of the lightweight and degradable nanocellulose / bamboo fiber thermal insulation material of this embodiment is as follows:

[0047] S1. Prefabrication of bamboo staple fibers: After removing the green, yellow and bamboo nodes of 6-year-old bamboo, split it vertically into bamboo strips with a length and width of 50×10 mm, put the bamboo strips into a mixed solution and stir and mix them at a rate of 60 r / min for 3 min, then heat them in a water bath at a temperature of 60° C. for 14 h until the bamboo strips turn white and the surface becomes soft, then wash them in running water at a flow rate of 0.6 m / s and a temperature of 40° C. until they are neutral, then put them into warm water at a temperature of 40° C., stir them at a rate of 120 r / min, and sieve them with a sieve with a mesh number of 200 to obtain bamboo staple fibers with an aspect ratio range of 60 to 90;

[0048] The solid-liquid ratio of the bamboo strips to the mixed solution is 1:1; the mixed solution is made of 30% by volume hydrogen peroxide and glacial acetic acid, and the volume of 30% by volume hydrogen peroxide and glacial acetic acid in the mixed solution is 1:1;

[0049] S2, bamboo fiber puffing: the bamboo short fibers obtained in S1 and a 1,4-butanediol aqueous solution with a mass fraction of 4% are mixed evenly, the mixture is heated to 95° C., stirred evenly, and then allowed to stand for 60 minutes, and filtered through a 200-mesh sieve to obtain puffed bamboo short fibers;

[0050] The solid-to-liquid ratio of the bamboo staple fibers to the 4% by mass 1,4-butanediol aqueous solution is 1:2;

[0051] S3, bamboo fiber reinforcement: the expanded bamboo staple fibers obtained in S2 and a 0.10% by mass dodecyltrimethylammonium bromide (DTAB) solution were mixed evenly, the pH value was adjusted to 11 with NaOH powder and then sealed, and then ultrasonically vibrated for 1 hour in a water bath at a temperature of 60° C., and then washed with distilled water until neutral to obtain modified bamboo staple fibers; the modified bamboo staple fibers were mixed with a 4% by mass nanocellulose solution, and stirred at a rate of 60 r / min for 10 minutes at a temperature of 30° C. to obtain a solid-liquid mixture;

[0052] The solid-liquid ratio of the puffed bamboo staple fibers to the dodecyltrimethylammonium bromide solution with a mass fraction of 0.10% is 1:30; the solid-liquid ratio of the modified bamboo staple fibers to the nanocellulose solution with a mass fraction of 4% is 1:5;

[0053] S4, high temperature short time thermoforming: pour the solid-liquid mixture obtained in S3 into a mold, and perform high temperature short time thermoforming treatment at a temperature of 190° C. and a time of 4 min / mm to obtain a nanocellulose / bamboo fiber thermal insulation material.

[0054] The nanocellulose / bamboo fiber thermal insulation material prepared in this embodiment can be used as a refrigerator thermal insulation material. The density of the nanocellulose / bamboo fiber thermal insulation material prepared in this embodiment is 0.115 g / cm 3 ; Thermal conductivity is 0.045W / mk; Degradation rate is 95.3%; Compressive strength is 0.6MPa.

[0055] Example 3

[0056] The preparation method of the lightweight and degradable nanocellulose / bamboo fiber thermal insulation material of this embodiment is as follows:

[0057] S1. Prefabrication of bamboo staple fibers: After removing the green, yellow and bamboo nodes of 6-year-old bamboo, split the bamboo strips vertically into bamboo strips with a length and width of 50×10 mm, put the bamboo strips into a mixed solution and stir and mix them at a rate of 60 r / min for 3 min, then heat them in a water bath at a temperature of 60° C. for 14 h, then wash them in running water at a flow rate of 0.6 m / s and a temperature of 35° C. until they are neutral, then put them into warm water at a temperature of 35° C., stir them at a rate of 120 r / min, and sieve them with a sieve with a mesh number of 200 to obtain bamboo staple fibers with an aspect ratio range of 60 to 90;

[0058] The solid-liquid ratio of the bamboo strips to the mixed solution is 1:1; the mixed solution is made of 30% by volume hydrogen peroxide and glacial acetic acid, and the volume of 30% by volume hydrogen peroxide and glacial acetic acid in the mixed solution is 1:1;

[0059] S2, bamboo fiber puffing: the bamboo short fibers obtained in S1 and a 1,4-butanediol aqueous solution with a mass fraction of 5% were mixed evenly, the mixture was heated to 93° C., stirred evenly, and then allowed to stand for 50 minutes, and filtered through a 200-mesh sieve to obtain puffed bamboo short fibers;

[0060] The solid-to-liquid ratio of the bamboo staple fibers to the 5% by mass 1,4-butanediol aqueous solution is 1:2;

[0061] S3, bamboo fiber reinforcement: the expanded bamboo staple fibers obtained in S2 and a 0.08% by mass dodecyltrimethylammonium bromide (DTAB) solution were mixed evenly, the pH value was adjusted to 11 with NaOH powder and then sealed, and then ultrasonically vibrated for 1 hour in a water bath at a temperature of 60° C., and then washed with distilled water until neutral to obtain modified bamboo staple fibers; the modified bamboo staple fibers were mixed with a 5% by mass nanocellulose solution, and stirred at a rate of 60 r / min for 20 minutes at a temperature of 28° C. to obtain a solid-liquid mixture;

[0062] The solid-liquid ratio of the puffed bamboo staple fibers to the dodecyltrimethylammonium bromide solution with a mass fraction of 0.08% is 1:30; the solid-liquid ratio of the modified bamboo staple fibers to the nanocellulose solution with a mass fraction of 5% is 1:5;

[0063] S4, high temperature short time thermoforming: pour the solid-liquid mixture obtained in S3 into a mold, and perform high temperature short time thermoforming treatment at a temperature of 200° C. and a time of 5 min / mm to obtain a nanocellulose / bamboo fiber thermal insulation material.

[0064] The nanocellulose / bamboo fiber thermal insulation material prepared in this embodiment can be used as a thermal insulation material for refrigerated vehicles. The density of the nanocellulose / bamboo fiber thermal insulation material prepared in this embodiment is 0.105 g / cm 3 ; Thermal conductivity is 0.039W / mk; Degradation rate is 96.1%; Compressive strength is 0.7MPa.

[0065] The mold used in Examples 1-3 is designed and customized according to the specifications of the required nanocellulose / bamboo fiber thermal insulation material. The function of the mold is only to allow the solid-liquid mixture to remain stationary therein. Different shapes can be customized according to the shape of the required nanocellulose / bamboo fiber thermal insulation material, and it mainly plays the role of fixing the shape. The mold needs to consider the ease of operation when demoulding the nanocellulose / bamboo fiber thermal insulation material. At the same time, materials with good thermal conductivity such as aluminum and stainless steel can be used. It can also be a ready-made mold, but the sealing of the lower mold needs to be improved to prevent the solid-liquid mixture from being lost.

[0066] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material, characterized in that: The method is: S1. Prefabrication of bamboo staple fibers: After removing green, yellow and bamboo nodes from bamboo, splitting the bamboo strips vertically, placing the bamboo strips in a mixed solution and stirring to mix, then heating the solution in a water bath, washing the solution in running water until neutral, placing the solution in warm water, stirring and sieving the solution to obtain bamboo staple fibers; the temperature of the warm water is 25-40° C.; S2, bamboo fiber puffing: the bamboo short fibers obtained in S1 and a 1,4-butanediol aqueous solution with a mass fraction of 3-5% are mixed evenly, the mixture is heated to 90-95° C., stirred evenly, and then allowed to stand for 40-60 minutes, and filtered through a sieve to obtain puffed bamboo short fibers; S3, bamboo fiber reinforcement: the expanded bamboo staple fibers obtained in S2 and the dodecyl trimethyl ammonium bromide solution with a mass fraction of 0.05-0.10% are mixed evenly, the pH value is adjusted to 11 with NaOH powder, and then sealed, and then ultrasonically vibrated in a water bath environment, and then washed with distilled water until neutral to obtain modified bamboo staple fibers; the modified bamboo staple fibers are mixed evenly with the nanocellulose solution, and stirred at a temperature of 25-30° C. for 10-30 minutes to obtain a solid-liquid mixture; S4, high temperature short time thermoforming: pouring the solid-liquid mixture obtained in S3 into a mold, and performing high temperature short time thermoforming treatment to obtain a nanocellulose / bamboo fiber thermal insulation material; The high temperature short time thermoforming treatment has a temperature of 190-200° C. and a time of 3-5 min / mm.

2. The method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material according to claim 1, characterized in that: The bamboo described in S1 is 6-year-old bamboo; the length and width of the bamboo strips are 50×10 mm; the temperature of the water bath heating is 60° C., and the time is 14 h.

3. The method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material according to claim 1, characterized in that: The solid-liquid ratio of the bamboo strips and the mixed solution in S1 is 1:1; the mixed solution is made of 30% by volume hydrogen peroxide and glacial acetic acid, and the volume ratio of 30% by volume hydrogen peroxide and glacial acetic acid in the mixed solution is 1:

1.

4. The method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material according to claim 1, characterized in that: The flow rate of the water in S1 is 0.6 m / s, and the temperature is 25-40° C.; the stirring and mixing time is 3 min.

5. The method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material according to claim 1, characterized in that: The mesh number of the sieve used for screening in S1 is 200 mesh; the aspect ratio of the bamboo staple fibers is in the range of 60-90.

6. The method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material according to claim 1, characterized in that: The solid-to-liquid ratio of the bamboo staple fibers in S2 to the 1,4-butanediol aqueous solution with a mass fraction of 3-5% is 1:

2.

7. The method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material according to claim 1, characterized in that: The mesh number of the sieve described in S2 is 200 meshes.

8. The method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material according to claim 1, characterized in that: In S3, the solid-to-liquid ratio of the puffed bamboo staple fibers to the dodecyltrimethylammonium bromide solution with a mass fraction of 0.05-0.10% is 1:30; the temperature of the water bath environment is 60° C., and the ultrasonic oscillation time is 1 hour.

9. The method for preparing a lightweight and degradable nanocellulose / bamboo fiber thermal insulation material according to claim 1, characterized in that: The nanocellulose solution in S3 is made of water and nanocellulose, and the mass fraction of nanocellulose in the nanocellulose solution is 3-5%; the solid-liquid ratio of the modified bamboo short fibers to the nanocellulose solution is 1:5.

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