Micro-nano wood fiber preparation method and method for preparing cellulose composite material by using wood fiber

Abstract

The invention provides a micro-nano wood fiber preparation method and a method for preparing a cellulose composite material by using wood fibers, and the method comprises the following steps: crushing a lignocellulose raw material into powder to obtain lignocellulose powder with uniform granularity; preparing a mixed solution of sodium hydroxide and urea; adding the sieved lignocellulose powder into the mixed solution, and continuously stirring for a set time to achieve a swelling effect; washing the product after the reaction in the previous step by using deionized water until the supernatant is neutral; preparing choline chloride, citric acid and distilled water into a solution to obtain a deep eutectic solvent; adding the product which is washed to be neutral into the deep eutectic solvent according to a set proportion, and crushing by using an ultrasonic cell crusher at set power; washing the product after the reaction in the previous step by using deionized water until the supernatant is neutral; and oxidizing the obtained product in a sodium periodate solution to obtain the micro-nano lignocellulose.

Description

Technical Field

[0001] The present invention belongs to the field of micro-nano preparation and functional application of wood fibers, and specifically relates to a method for preparing micro-nano wood fibers and a method for preparing composite materials using wood fibers. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The widespread use of petroleum-based plastics and their non-degradability have led to environmental pollution problems, prompting researchers to continuously search for biodegradable materials to reduce dependence on petroleum-based products. Lignocellulose, as a naturally derived polymer, has attracted much attention due to its high yield, renewability, low cost and natural degradability.

[0004] By decomposing the structure of cellulose step by step, fibrillated fibers extending to the nanoscale can be obtained, and the size can be controlled. The development of nanotechnology has enabled lignocellulosic biomass resources to be used to directly separate nanocellulose. However, due to the large number of intermolecular hydrogen bonds inside it, the crystallinity is high, making it difficult to achieve its micro-nanoization. In chemical wet processing, the use of a large amount of chemical pollutants seriously violates the requirements of green and sustainable development. In mechanical dry processing, although the generation of waste chemicals that cause environmental pollution is avoided, there are problems of lack of supporting equipment and high energy consumption.

[0005] At the same time, the processing of thermoplastic materials depends on the flow of molecular chains when heated. The hydrogen bonds between cellulose molecular chains are extremely strong and tightly bound. The melting temperature is much higher than its thermal decomposition temperature, making it difficult for the molecular chains to slip or rearrange when heated. It will decompose or carbonize before being heated to a molten state, so it cannot exhibit similar thermoplastic properties, hindering its functional application. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a low-pollution, low-energy consumption method for the micro-nano preparation and functionalization of wood fibers. The preparation process of the present invention uses chemical reagents with less impact on the environment and combines them with mechanical treatment to prepare micro-nano wood fiber powder. By blending and extruding it with the biodegradable material polylactic acid (PLA), a fully biodegradable composite material is prepared, which provides ideas for the functional application of wood cellulose and reducing the cost of biodegradable materials.

[0007] To achieve the above objectives, the present invention is implemented through the following technical means:

[0008] In a first aspect, the present invention provides a low-pollution, low-energy consumption method for preparing wood fiber micronized nanostructures, comprising the following steps:

[0009] Step 1: crushing the lignocellulose raw material into a powder state and preliminarily screening it to obtain lignocellulose powder with uniform particle size;

[0010] Step 2: Prepare a mixed solution of sodium hydroxide and urea and stir evenly;

[0011] Step 3: adding the sieved lignocellulose powder to the mixed solution and stirring for a set time to achieve a swelling effect;

[0012] Step 4: washing the product after the reaction in step 3 with deionized water until the supernatant is neutral;

[0013] Step 5: preparing a solution of choline chloride, citric acid and distilled water, and stirring the solution at a set temperature until the solution becomes clear, thereby obtaining a deep eutectic solvent;

[0014] Step 6: adding the product washed to neutrality in step 1 to the deep eutectic solvent in a set ratio, and crushing the product using an ultrasonic cell disruptor at a set power;

[0015] Step 7: washing the product after the reaction in step 6 with deionized water until the supernatant is neutral;

[0016] Step 8: The product obtained in step 7 is oxidized in a sodium periodate solution to obtain micro-nano lignocellulose.

[0017] As a further technical solution, the sieve can be a sieve with a mesh size of 200 or above to improve the accessibility of subsequent reactions.

[0018] As a further technical solution, in order to achieve energy conservation and emission reduction, the total content of choline chloride and citric acid in the deep eutectic solvent is greater than or equal to 30%.

[0019] As a further technical solution, the lignocellulose raw materials include but are not limited to wheat straw, corn straw, bagasse, and eggplant straw. All natural biomass raw materials rich in lignocellulose can be obtained by this method.

[0020] As a further technical solution, the mixed solution in step 2 contains 7-9 wt% sodium hydroxide and 12-15 wt% urea, preferably 8 wt% sodium hydroxide and 14 wt% urea.

[0021] As a further technical solution, in step 6, the product washed to neutrality in step 1 is added to a deep eutectic solvent, and the mass fraction is limited by the concentration of the deep eutectic solvent due to the dispersibility of the raw materials.

[0022] In a second aspect, the present invention further provides a method for preparing a composite material using wood fibers, comprising the following steps:

[0023] Step 1: uniformly mixing the micro-nano lignocellulose powder obtained by the preparation method described above and polylactic acid at a mass ratio of 1:1 to obtain a mixed raw material;

[0024] Step 2: Set the barrel zone 1, barrel zone 2, and mold zone 1 of the extruder to the set temperature and keep them stable;

[0025] Step 3: adding the mixed raw material obtained in step 1 into an extruder, and extruding the filament at a set speed;

[0026] Step 4: crushing the obtained mixed filaments of wood fiber and polylactic acid into powder, using a hot press to hot press at a set pressure and temperature for a set time, and maintaining the pressure for a set time to obtain a cellulose / PLA composite material.

[0027] As a further technical solution, the mass ratio of the micro-nano lignocellulose powder to polylactic acid can be adjusted to 1:1, 1:1.25, 1.25:1, 1.5:1 or other ratios.

[0028] As a further technical solution, the method for preparing a composite material using wood fibers can also be used for the composite preparation of wood fibers of other particle sizes and polylactic acid.

[0029] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0030] The present invention uses DES solvent as a reaction medium, which is sustainable and reusable. It is a renewable, cheap and green solvent, which greatly reduces pollution to the environment.

[0031] The present invention uses a combination of chemical and mechanical methods to prepare micronized wood fiber powder. The wood fiber is pretreated by chemical swelling, and then an ultrasonic cell disruptor is used to complete the treatment in a shorter time. Compared with chemical methods that require a long reaction time, the production efficiency is greatly improved.

[0032] The present invention provides a solution for the problem that wood fiber cannot be thermally processed and formed. By co-extruding with biodegradable materials, the functional application of wood fiber is achieved. Since biodegradable materials are expensive, the present invention also provides a feasible solution for reducing material costs.

[0033] The present invention also studies the effect of micronization on the mechanical properties of composite materials. The results show that the micronized wood fibers have more binding sites and have better interfacial compatibility with PLA materials compared with wood fiber powders with larger particle sizes (50 mesh, 100 mesh, 200 mesh, and 500 mesh). BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0035] Figure 1 This is a flow chart of the micronized preparation of wood fiber and the preparation of wood fiber / PLA composite samples in Example 1;

[0036] Figure 2 This is the actual effect diagram of the micro-nano preparation of wood fiber. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] The present invention will be further described below with reference to the embodiments.

[0039] This embodiment provides a method for preparing micronized wood fibers, comprising the following steps:

[0040] Step 1: crushing the lignocellulose raw material into a powder state and preliminarily screening it to obtain lignocellulose powder with uniform particle size;

[0041] Step 2, preparing a mixed solution of sodium hydroxide and urea;

[0042] Step 3: adding the sieved lignocellulose powder to the mixed solution and stirring for a set time to achieve a swelling effect;

[0043] Step 4: Wash the product after the reaction in step 3 with deionized water until the supernatant is neutral;

[0044] Step 5: prepare a solution of choline chloride, citric acid and distilled water, and stir the solution at a set temperature until the solution becomes clear, thereby obtaining a deep eutectic solvent;

[0045] Step 6: adding the product washed to neutrality in step 1 to the deep eutectic solvent in a set ratio, and crushing the product using an ultrasonic cell disruptor at a set power;

[0046] Step 7: washing the product after the reaction in step 6 with deionized water until the supernatant is neutral;

[0047] Step 8: Oxidize the product obtained in step 7 in a sodium periodate solution to obtain micro-nano lignocellulose.

[0048] The following examples illustrate the preparation of micronized wood fiber from wheat straw. Of course, the processed wood cellulose raw materials are not limited to wheat straw. They can also be other crop straws (corn straw, bagasse, eggplant straw, etc.), softwood conifers (pine, fir, fir, larch, etc.), hardwood broadleaf trees (poplar, eucalyptus, maple, oak, etc.), and other natural biomass raw materials rich in wood cellulose. The overall preparation process remains unchanged; the power of the ultrasonic cell disruptor needs to be changed according to the hardness of the wood fiber from different sources.

[0049] Example 1

[0050] This embodiment provides a method for preparing micronized wood fibers, comprising the following steps:

[0051] Step 1: Select 50g of wheat straw and add it to 500ml of NaOH / Urea mixed solution. Stir at room temperature for 3h. The mass fractions of NaOH and Urea are 8% and 14%, respectively. After sufficient swelling, wash with deionized water until the supernatant is neutral. Take out the product for use.

[0052] Step 2: The product of step 1 was mixed evenly with 500 ml of DES solvent, wherein the DES solvent was prepared by preparing a 30 wt% solution of ChCl and CA in a molar ratio of 1:2 with distilled water. The thoroughly mixed solution was disrupted using an ultrasonic cell disruptor at 800 W for 30 minutes, and washed with deionized water until the supernatant was neutral. The product was removed for use.

[0053] Step 3: The product of step 2 was added to 500 ml of NaIO4 solution, wherein the mass fraction of the NaIO4 solution was 5 wt%, and the mixture was stirred and oxidized for 3 h in a 40 ° C water bath in the dark. The mixture was washed with deionized water until the supernatant was neutral. The product was taken out and dried at 60 ° C for 24 h to obtain micro-nano lignocellulose (WNLC).

[0054] Furthermore, based on the micro-nano lignocellulose obtained above, the method for preparing the WNLC / PLA composite material is as follows:

[0055] Step 4: The WNLC powder prepared in step 3 was mixed with PLA at a mass ratio of 1:1 to obtain a mixed raw material WNLC / PLA.

[0056] Step 5: Add the WNLC / PLA obtained in step 4 to the extruder, extrude the filaments at a speed of 15 rpm and crush them into powder for later use, wherein the barrel zone 1, barrel zone 2, and mold zone 1 of the extruder are all set to 130°C.

[0057] Step 6: The extruded WNLC / PLA powder was hot-pressed at 0.6 MPa and 150°C for 5 minutes, followed by a holding period of 2 minutes to obtain a WNLC / PLA composite material. The sample properties were tested, and the results are listed in Table 1.

[0058] Example 2

[0059] This embodiment provides a method for preparing micronized wood fibers, comprising the following steps:

[0060] Step 1: Select 50g of wheat straw and add it to 500ml of NaOH / Urea mixed solution. Stir at room temperature for 3h. The mass fractions of NaOH and Urea are 8% and 14%, respectively. After sufficient swelling, wash with deionized water until the supernatant is neutral. Take out the product for use.

[0061] Step 2: The product of step 1 was mixed evenly with 625 ml of DES solvent, wherein the DES solvent was prepared by preparing a 40 wt% solution of ChCl and CA in a molar ratio of 1:2 with distilled water. The thoroughly mixed solution was disrupted using an ultrasonic cell disruptor at 800 W for 40 minutes, and washed with deionized water until the supernatant was neutral. The product was removed for use.

[0062] Step 3: The product of step 2 was added to 500 ml of NaIO4 solution (mass fraction of NaIO4 solution was 5 wt%), and oxidized by stirring for 3 h in a 40°C water bath in the dark. The product was washed with deionized water until the supernatant was neutral. The product was removed and dried at 70°C for 18 h to obtain WNLC.

[0063] The main differences between the micronized wood fiber preparation method in this embodiment and that in Example 1 are that the concentration of the DES solvent is increased. As the DES concentration increases, the cell disruption time also changes: a higher DES concentration results in a longer cell disruption time. Furthermore, due to the dispersibility of wheat straw in the DES solvent, a higher DES solvent concentration results in a lower wheat straw mass fraction. As described in Example 2, a 40 wt% DES solvent preferably has an 8 wt% mass fraction. Furthermore, the WNLC drying temperature and time in this embodiment differ from those in Example 1. The WNLC drying temperature and time are variable, with the higher the temperature, the shorter the drying time.

[0064] Furthermore, based on the micro-nano lignocellulose obtained above, the method for preparing the WNLC / PLA composite material still includes steps 4 to 6 in Example 1, which are the same as Example 1 and will not be described in detail here.

[0065] In Examples 1-2 above, DES solvent was used as the reaction medium. This solvent is sustainable, reusable, renewable, inexpensive, and green, significantly reducing environmental pollution. A combination of chemical and mechanical methods was used to prepare micronized wood fiber powder. The wood fiber was pretreated by chemical swelling, and then an ultrasonic cell disruptor was used to complete the treatment in a shorter time. This significantly improved production efficiency compared to chemical methods that require a long reaction time.

[0066] Example 3

[0067] This embodiment provides a method for preparing micronized wood fibers, comprising the following steps:

[0068] Step 1: Select 50g of softwood coniferous tree (pine) sawdust and add it to 500ml of NaOH / Urea mixed solution. Stir at room temperature for 3h. The mass fractions of NaOH and Urea are 8% and 14%, respectively. After sufficient swelling, wash with deionized water until the supernatant is neutral. Remove the product and set aside.

[0069] Step 2: The product of step 1 was mixed evenly with 500 ml of DES solvent, wherein the DES solvent was prepared by preparing a 30 wt% solution of ChCl and CA in a molar ratio of 1:2 with distilled water. The thoroughly mixed solution was disrupted using an ultrasonic cell disruptor at 1500 W for 30 minutes, and washed with deionized water until the supernatant was neutral. The product was removed for use.

[0070] Step 3: The product of step 2 was added to 500 ml of NaIO4 solution, wherein the mass fraction of the NaIO4 solution was 5 wt%, and the mixture was stirred and oxidized for 3 h in a 40 ° C water bath in the dark. The mixture was washed with deionized water until the supernatant was neutral. The product was taken out and dried at 60 ° C for 24 h to obtain micro-nano lignocellulose (WNLC).

[0071] The main difference between the method for preparing micronized wood fiber in this embodiment and that in Example 1 is that the hardness of wood fiber from softwood conifers (pine trees) is higher than that of crop straw (wheat straw), so the power of the ultrasonic cell disruptor is increased to 1500W.

[0072] Furthermore, based on the micro-nano lignocellulose obtained above, the method for preparing the WNLC / PLA composite material still includes steps 4 to 6 in Example 1, which are the same as Example 1 and will not be described in detail here.

[0073] Example 4

[0074] This embodiment provides a method for preparing micronized wood fibers, comprising the following steps:

[0075] Step 1: Select 50g of hardwood broadleaf tree (poplar) sawdust and add it to 500ml of NaOH / Urea mixed solution. Stir at room temperature for 3h. The mass fractions of NaOH and Urea are 8% and 14%, respectively. After sufficient swelling, wash with deionized water until the supernatant is neutral. Remove the product and set aside.

[0076] Step 2: The product of step 1 was mixed evenly with 500 ml of DES solvent, wherein the DES solvent was prepared by preparing a 30 wt% solution of ChCl and CA in a molar ratio of 1:2 with distilled water. The thoroughly mixed solution was disrupted using an ultrasonic cell disruptor at 1200 W for 30 minutes, and washed with deionized water until the supernatant was neutral. The product was removed for use.

[0077] Step 3: The product of step 2 was added to 500 ml of NaIO4 solution, wherein the mass fraction of the NaIO4 solution was 5 wt%, and the mixture was stirred and oxidized for 3 h in a 40 ° C water bath in the dark. The mixture was washed with deionized water until the supernatant was neutral. The product was taken out and dried at 60 ° C for 24 h to obtain micro-nano lignocellulose (WNLC).

[0078] The main difference between the method for preparing micronized wood fibers in this embodiment and that in Example 1 is that the hardness of wood fibers from hardwood broad-leaved trees (poplars) is higher than that from crop straw (wheat straw) and lower than that from softwood coniferous trees (pines), so the power of the ultrasonic cell disruptor is increased to 1200W.

[0079] Furthermore, based on the micro-nano lignocellulose obtained above, the method for preparing the WNLC / PLA composite material still includes steps 4 to 6 in Example 1, which are the same as Example 1 and will not be described in detail here.

[0080] Example 5

[0081] The method for preparing micronized wood fiber proposed in this embodiment still includes steps 1 to 3. The specific steps are the same as those in embodiment 1 and will not be described in detail here.

[0082] Based on the micro-nano lignocellulose obtained above, the method for preparing the WNLC / PLA composite material proposed in this embodiment is as follows:

[0083] Step 4: The WNLC powder prepared in step 3 was mixed with PLA at a mass ratio of 1.25:1 to obtain a mixed raw material WNLC / PLA.

[0084] Step 5: Add the WNLC / PLA obtained in step 4 to the extruder, extrude the filaments at a speed of 15 rpm and crush them into powder for later use, wherein the barrel zone 1 of the extruder is set to 140°C, the barrel zone 2 is set to 140°C, and the mold zone 1 is set to 130°C.

[0085] Step 6: The extruded WNLC / PLA powder was hot-pressed at 0.6 MPa and 155° C. for 5 min to obtain a WNLC / PLA composite material.

[0086] The difference between this embodiment and Example 1 is that the ratio of the two components in WNLC / PLA is changed. To adapt to the change in the ratio of the components, the temperature of the extruder is changed at the same time.

[0087] Example 6

[0088] This example proposes a method for preparing a cellulose / PLA composite material using wood fibers of other particle sizes, as follows:

[0089] Step 1: Pass the mechanically ground and crushed wheat straw powder through a 50-mesh sieve and set aside.

[0090] Step 2: The 50-mesh wheat straw obtained in step 1 was stirred and evenly mixed with PLA to obtain a 50-mesh / PLA raw material, which was added to an extruder. The filaments were extruded at a speed of 15 rpm and crushed into powder for later use. The barrel zone 1, barrel zone 2, and mold zone 1 of the extruder were all set to 130°C.

[0091] Step 3: The extruded 50 mesh / PLA powder was hot pressed at 0.6 MPa and 150° C. for 5 min using a hot press, and the pressure was maintained for 2 min to obtain a 50 mesh / PLA composite material.

[0092] Similarly, according to the scheme in Example 6, 100 mesh / PLA, 200 mesh / PLA, and 500 mesh / PLA composite materials can also be prepared, and the sample properties are tested. The results are listed in Table 1. That is, the functionalization application methods of the micronized wood fibers proposed in Examples 1, 2, and 5 are also applicable to wood fibers of other particle sizes. When the functionalization application methods of the micronized wood fibers proposed in Examples 1, 2, and 5 are used for wood fibers of other particle sizes, the main difference is that the 50 mesh, 100 mesh, 200 mesh, and 500 mesh wood fibers can be obtained by traditional mechanical grinding and pulverization, without the need for the chemical treatment in steps 1-3 of Examples 1, 2, and 5.

[0093] This example verifies the benefits of micronization by testing mechanical properties, as follows:

[0094] Comparative Example 1

[0095] Step 1: PLA was added to an extruder, and filaments were extruded at a speed of 15 rpm and crushed into powder for later use. The barrel zone 1, barrel zone 2, and mold zone 1 of the extruder were all set to 130°C.

[0096] Step 2: The extruded PLA was hot-pressed at 0.6 MPa and 150° C. for 5 min using a hot press, and the pressure was maintained for 2 min to obtain a PLA hot-pressed sample. The sample properties were tested, and the results are listed in Table 1.

[0097] According to Table 1,

[0098] PLA exhibited a tensile strength of 6.90 MPa and a compressive strength of 48.76 MPa. The addition of wood fiber powder at a mass ratio of 1:1 significantly enhanced both tensile and compressive strengths. The addition of 50-mesh wood fiber powder increased the tensile strength by 6.38%, while the compressive strength remained largely stable. As the particle size of the added wood fiber decreased, the mechanical properties of the resulting composite gradually improved. When WNLC was added, the WNLC / PLA composite exhibited a tensile strength of 14.5 MPa and a compressive strength of 83.63 MPa, representing increases of 110.14% and 71.51% respectively compared to the PLA composite. Compared to the 50-mesh PLA composite, the tensile strength increased by 97.55% and the compressive strength increased by 70.78%. This suggests that the micronized wood fibers provide more bonding sites during the melt extrusion process, allowing for closer bonding between the composite components and improving the mechanical properties.

[0099] Table 1 Performance comparison of wood fiber particles of different fineness and polylactic acid composites

[0100]

[0101] The above-mentioned Examples 1-6 provide ideas for the problem that wood fiber cannot be thermally processed and formed. By co-extruding with biodegradable materials, the functional application of wood fiber is completed. Since biodegradable materials are expensive, the present invention also provides a feasible solution for reducing material costs; and at the same time, the effect of micro-nanoization on the mechanical properties of composite materials is studied. The results show that the micro-nanoized wood fiber has more binding sites, and compared with wood fiber powder with larger particle size (50 mesh, 100 mesh, 200 mesh, 500 mesh), the micro-nanoized wood fiber has better interface compatibility with PLA material.

[0102] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing micro-nano wood fiber, characterized in that: The steps include: Step 1: crushing the lignocellulose raw material into a powder state and preliminarily screening it to obtain lignocellulose powder with uniform particle size; Step 2, preparing a mixed solution of sodium hydroxide and urea; Step 3: adding the sieved lignocellulose powder to the mixed solution and stirring for a set time to achieve a swelling effect; Step 4: Wash the product after the reaction in step 3 with deionized water until the supernatant is neutral; Step 5: prepare a solution of choline chloride, citric acid and distilled water, and stir the solution at a set temperature until the solution becomes clear, thereby obtaining a deep eutectic solvent; Step 6: adding the product washed to neutrality in step 1 to the deep eutectic solvent in a set ratio, and crushing the product using an ultrasonic cell disruptor at a set power; Step 7: washing the product after the reaction in step 6 with deionized water until the supernatant is neutral; Step 8: Oxidize the product obtained in step 7 in a sodium periodate solution to obtain micro-nano lignocellulose.

2. The method for preparing micronized wood fiber according to claim 1, wherein: The sieve is a sieve with a mesh size of 200 or more.

3. The method for preparing micronized wood fiber according to claim 1, wherein: The total content of choline chloride and citric acid in the deep eutectic solvent is greater than or equal to 30%.

4. The method for preparing micronized wood fiber according to claim 1, wherein: The lignocellulose raw materials include but are not limited to wheat straw, corn straw, bagasse, and eggplant straw.

5. The method for preparing micronized wood fiber according to claim 1, wherein: The mixed solution in step 2 contains 7-9 wt % of sodium hydroxide and 12-15 wt % of urea.

6. The method for preparing micronized wood fiber according to claim 1, wherein: The mixed solution in step 2 contains 8 wt % of sodium hydroxide and 14 wt % of urea.

7. The method for preparing micronized wood fiber according to claim 1, wherein: In the step 6, the product washed to neutrality in step 1 is added to the deep eutectic solvent, and the mass fraction is limited by the concentration of the deep eutectic solvent due to the dispersibility of the raw materials.

8. A method for preparing a cellulose composite material using wood fiber, characterized in that: The steps include: Step 1: uniformly mixing the micro-nano lignocellulose powder obtained by the preparation method according to claims 1-7 and polylactic acid at a mass ratio of 1:1 to obtain a mixed raw material; Step 2: Set the barrel zone 1, barrel zone 2, and mold zone 1 of the extruder to the set temperature and keep them stable; Step 3: adding the mixed raw material obtained in step 1 into an extruder, and extruding the filament at a set speed; Step 4: crushing the obtained mixed filaments of wood fiber and polylactic acid into powder, using a hot press to hot press at a set pressure and temperature for a set time, and maintaining the pressure for a set time to obtain a cellulose / PLA composite material.

9. The method for preparing a cellulose composite material using wood fibers according to claim 8, wherein: The steps include: The mass ratio of the micro-nano lignocellulose powder to the polylactic acid can be adjusted to 1:1, 1:1.25, 1.25:1, 1.5:1 or other ratios.

10. The method for preparing a cellulose composite material using wood fibers according to claim 8, wherein: It can also be used for the composite preparation of wood fibers of other particle sizes and polylactic acid.

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