A bamboo-based composite material modified based on white rot fungus and a preparation method thereof

Abstract

This invention discloses a bamboo-based composite material modified by white-rot fungi and its preparation method, relating to the field of composite material technology. The modification process includes: preparing *Phyllostachys edulis* bamboo chips and sterile water at a mass ratio of 1:20-1:25, culturing in a shaker at 25℃-30℃ and 150-180 rpm; maintaining a mass ratio of bamboo chips to white-rot fungi of 1:1-3:1; adding 5 g / L of *Phyllostachys edulis* bamboo powder to the solution; and culturing in the shaker for 10-30 days. After white-rot fungi treatment, the bamboo chips are dried. The bamboo-based composite material obtained by this invention exhibits significantly improved density, tensile strength, and bonding strength, belonging to a high-density, high-strength bamboo-based composite material with broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, and in particular to a bamboo-based composite material modified by white-rot fungi and its preparation method. Background Technology

[0002] Due to increasing emphasis on the environment and natural resources, the research and development of biomass composite materials has received growing attention. Wood-based composite products are mainly made from wood fibers and particles through various manufacturing methods such as hot pressing, and have wide applications in construction, packaging, furniture, and many other fields. Bamboo grows rapidly, and using bamboo to prepare bamboo-based composite materials can reduce costs. However, compared to wood, bamboo lacks transverse cells, has a denser cell structure, and contains more stone cells, resulting in poor adhesive permeability and difficulty in bonding. Consequently, the bonding strength of bamboo-based composite materials often fails to meet national standards.

[0003] To improve the physical and chemical properties of bamboo, such as its cell pore structure, wettability, and reactivity, and to increase its cellulose content and accessibility, thereby achieving excellent interfacial bonding and high mechanical strength in bamboo-based composites, bamboo is typically subjected to various pretreatments, including physical treatment, chemical treatment, thermal modification, and ion pretreatment. However, traditional physical or chemical treatments, as well as thermal treatments, are energy-intensive, require expensive equipment, and are environmentally unfriendly.

[0004] Compared with these methods, the use of fungal pretreatment to modify bamboo, change the physicochemical properties of bamboo, and prepare bamboo-based composite materials based on white-rot fungi-modified giant bamboo has positive significance for the technical field of bamboo composite material preparation. Summary of the Invention

[0005] The main technical problem solved by this invention is the need to improve the physical and chemical properties of raw materials, such as cell pore structure, wettability, and reactivity, in the preparation of common bamboo composite materials. Traditional pretreatment methods are costly and environmentally unfriendly.

[0006] Therefore, this invention provides a bamboo-based composite material modified by white-rot fungi and its preparation method, and a method for preparing bamboo-based composite materials by hot pressing of fungal-modified bamboo strips. Under the culture conditions of this invention, white-rot fungi efficiently secrete lignin oxidase laccase. After pretreatment by white-rot fungi, the chemical composition of *Phyllostachys edulis* changes under the action of laccase secreted by the fungi. The lignin side chains break, and the macromolecular structure undergoes degradation or depolymerization, resulting in increased reactivity. At the same time, the pore structure of bamboo cells changes, wettability is significantly improved, and the crystallinity of bamboo increases. Therefore, the bamboo-based composite material prepared by white-rot fungi modification has significantly improved density, tensile strength, and bonding strength, belonging to high-density and high-strength bamboo-based composite materials with broad application prospects.

[0007] The objective of this invention is achieved as follows:

[0008] A method for preparing a bamboo-based composite material modified by white-rot fungi, comprising modification treatment:

[0009] Giant dragon bamboo slices and sterile water were prepared at a mass ratio of 1:20-1:25 and cultured in a shaker at 25℃-30℃ and 150-180 rpm. The mass ratio of bamboo slices to white-rot fungus was 1:1-3:1. 5 g / L of giant dragon bamboo powder was added to the solution, and the mixture was cultured in the shaker for 10-30 days. After white-rot fungus treatment, the bamboo slices were dried. This method aims to improve the physical and chemical properties of giant dragon bamboo slices, including cell pore structure, wettability, and reactivity.

[0010] Furthermore, the white-rot fungus is *Amanita muscaria*.

[0011] Furthermore, the thickness of the bamboo strips of Giant Dragon Bamboo is 0.8-1.5mm.

[0012] Furthermore, the mass ratio of bamboo chips to sterile water was 1:20, and the culture conditions were as follows: culturing in shakers at 25℃ and 150 rpm and 28℃ and 180 rpm; the mass ratio of bamboo chips to white-rot fungi was 3:1; 5 g / L of *Phyllostachys edulis* powder was added to the solution; and the bamboo chips were removed and dried after culturing in shakers for 30 days. Under these conditions, the *Phyllostachys edulis* bamboo chips prepared exhibited the highest wettability, tensile strength, and the density, tensile strength, and bonding strength of the bamboo-based composite material.

[0013] This invention also relates to a method for preparing a bamboo-based composite material modified by white-rot fungi, comprising:

[0014] Drying: Air-dry or oven-dry the bamboo strips modified by the white-rot fungus; the modification treatment is carried out according to the preparation method described above;

[0015] Apply adhesive: Apply commercially available urea-formaldehyde resin adhesive;

[0016] Paving: Lay three layers of bamboo strips along the grain;

[0017] Hot pressing: The laid bamboo strips are hot-pressed at 130-180℃ and 1.5-5.0MPa for 6-10 minutes to obtain a bamboo-based composite material modified by white rot fungi.

[0018] Furthermore, the bamboo strips are air-dried for 24 hours or dried at 60℃ for 6 hours.

[0019] Furthermore, during the adhesive application process, the adhesive application rate is 170g / m². 2 .

[0020] Furthermore, the laid bamboo strips are hot-pressed at 130-180℃ and 1.5-5.0MPa for 6-10 minutes.

[0021] The present invention also relates to a bamboo-based composite material modified by white-rot fungi, which is prepared by the above-described preparation method.

[0022] This invention first utilizes white-rot fungi to modify *Phyllostachys edulis* bamboo strips for different durations. The modified bamboo strips are then dried, coated with commercially available urea-formaldehyde resin adhesive, laid along the grain, and hot-pressed to prepare a bamboo-based composite material modified by white-rot fungi. By detecting the enzyme activity secreted by white-rot fungi at different modification stages and by testing the physical and mechanical properties of the bamboo-based composite material, it was found that under the cultivation conditions of this invention, white-rot fungi efficiently secrete laccase, a lignin oxidase, to modify lignin, causing its side chains to break, macromolecules to degrade into smaller molecules, and increasing its reactivity. After modification by white-rot fungi, under the action of highly active laccase secreted by the fungi, the chemical composition of *Phyllostachys edulis* changes, lignin side chains break, macromolecular structures undergo degradation or depolymerization, and reactivity increases. Simultaneously, the cell pore structure of the bamboo changes, wettability is significantly improved, and the crystallinity of the bamboo increases. Therefore, the bamboo-based composite material prepared by white-rot fungi modification exhibits significantly increased density, tensile strength, and bonding strength, belonging to a high-density, high-strength bamboo-based composite material with broad application prospects.

[0023] The challenge of this invention lies in improving ligninase activity. The activity of ligninase is increased by controlling the conditions to target and enhance it, while the activity of cellulase is very low. This is the only way to achieve targeted modification of lignin.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] (1) The pretreatment scheme used in this invention utilizes white-rot fungi that are widely found in nature. These fungi have a wide range of sources and are cultivated under mild and harmless conditions, which can alleviate the problems of high cost and environmental unfriendliness of traditional pretreatment schemes.

[0026] (2) Through the white-rot fungus pretreatment scheme of the present invention, compared with the untreated Giant Dragon Bamboo material, the wettability of Giant Dragon Bamboo chips modified by white-rot fungus was significantly improved, and the water contact angle decreased from the original 99.125° to 76.375°. Compared with bamboo chips that have not been modified by white-rot fungus, the bamboo chips modified by white-rot fungus have changed chemical composition and cell wall structure due to the partial degradation or depolymerization of lignin, and the increase of cell wall micropores. Therefore, the spreading and penetration of adhesives are effectively improved when preparing composite materials. In addition, the reactivity of degraded lignin and degradation products is improved, and they can participate more in the reaction during hot pressing and bonding, forming a better interfacial bond, thereby improving the interfacial bonding performance of biomass composite materials. The interior of the composite material is more dense and uniform, so the physical and mechanical strength of the composite material is improved.

[0027] Under the conditions described in this claim, the tensile strength of *Phyllostachys edulis* bamboo chips pretreated with white-rot fungi increased from 142.08 MPa to 191.20 MPa, an increase of 134.6%. The prepared *Phyllostachys edulis* bamboo-based composite material, compared to the unmodified bamboo-based composite material, showed a 128% increase in density, from the original 0.836 g / cm³. 3 Increased to 1.070 g / cm³ 3 Compared with bamboo-based composites without fungal modification, the tensile strength increased by 129.5%, from 195.83 MPa to 253.58 MPa, and the bonding strength increased by 127.7%, from 4.88 MPa to 6.23 MPa.

[0028] Under the culture conditions of this invention, white-rot fungi efficiently secrete laccase, a lignin oxidase. During the 10-30 day treatment process, the laccase maintains high activity, achieving efficient modification of bamboo lignin. This process targets and breaks down lignin side chains without degrading the aromatic ring structure of lignin, breaking down large lignin molecules into smaller ones. Furthermore, the degradation of lignin side chains enhances its reactivity, promoting its role as an adhesive in the bonding process. During hot-press bonding, it participates more in cross-linking reactions, forming better interfacial bonding and resulting in improved adhesion. In addition, the change in chemical composition leads to a relative increase in cellulose content and crystallinity, positively impacting the mechanical strength of the composite material. Simultaneously, it improves the cell pore structure, wettability, and reactivity of bamboo, enhancing its physical and chemical properties. Therefore, the bamboo-based composite material obtained by pre-treating and modifying *Phyllostachys edulis* with white-rot fungi exhibits significantly improved density, tensile strength, and bonding strength. It is a high-density, high-strength wood-based composite material with broad application prospects. Attached Figure Description

[0029] Figure 1 (a) and (b) are the enzyme activities of ligninase secreted during the modification treatment of the white-rot fungus *Cyclocarya paliurus*. (a) is under the culture conditions of this invention (addition of 5 g / L *Phyllostachys nigra* powder), and (b) is under the culture conditions without the addition of *Phyllostachys nigra* powder.

[0030] Figure 2 (a) and (b) are the enzyme activities of hydrolytic enzymes (cellulosinase, cellulosinase and hemicellulosinase) secreted during the modification treatment of the white-rot fungus *Acer velutipes*. (a) is under the culture conditions of this invention (addition of 5 g / L *Bambusa multiplex* bamboo powder), and (b) is under the culture conditions without the addition of *Bambusa multiplex* bamboo powder.

[0031] Figure 3 The XPS spectrum of the surface of *Bamboo stalks* after modification by the white-rot fungus *Amanita muscaria* is shown. Figure 3(a), (b), (c), and (d) show the changes in the surface chemical properties of bamboo after 0, 10, 20, and 30 days of modification treatment with the white-rot fungus *Cymbidium goeringii*.

[0032] Figure 4 This refers to the water contact angle of Bambusa textilis after modification with white rot fungi.

[0033] Figure 5 The bonding strength of bamboo-based composite materials prepared by white-rot fungi modification;

[0034] Figure 6 It is the tensile strength of giant bamboo and bamboo-based composite materials after modification by white-rot fungi;

[0035] Figure 7 These are changes in the cell walls of *Phyllostachys edulis* after modification with white-rot fungi;

[0036] Figure 8 It is the bonding interface for bamboo-based composite materials prepared by white-rot fungi modification. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased.

[0038] Unless otherwise stated, all percentages in this invention represent mass fractions. Ratios are mass percentages, and concentrations are mass concentrations.

[0039] Example 1

[0040] The preparation method of bamboo-based composite material modified by white-rot fungi in this embodiment includes:

[0041] Pretreatment modification of Giant Dragon Bamboo with white rot fungus: The white rot fungus is *Amanita muscaria*, the thickness of Giant Dragon Bamboo slices is 1.0 mm, the mass ratio of Giant Dragon Bamboo slices to sterile water is 1:20, and it is cultured in a shaker at 25℃ and 150 rpm. The mass ratio of bamboo slices to white rot fungus is 3:1, 5 g / L of Giant Dragon Bamboo powder is added to the solution, and it is cultured in a shaker for 30 days. After white rot fungus treatment, the bamboo slices are dried.

[0042] Preparation of bamboo-based composite materials:

[0043] Drying: Air-dry the bamboo strips treated with white rot fungus for 24 hours;

[0044] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m².2 ;

[0045] Paving: Lay three layers of bamboo strips along the grain;

[0046] Hot pressing: The laid bamboo strips are hot-pressed at 150℃ and 5.0MPa for 10 minutes to obtain the bamboo-based composite material of Giant Dragon Bamboo based on white rot fungus pretreatment modification.

[0047] Example 2

[0048] The preparation method of bamboo-based composite material modified by white-rot fungi in this embodiment includes:

[0049] Pretreatment modification of Giant Dragon Bamboo with white rot fungus: The white rot fungus is *Amanita muscaria*, the thickness of Giant Dragon Bamboo slices is 1.0 mm, the mass ratio of Giant Dragon Bamboo slices to sterile water is 1:20, and it is cultured in a shaker at 28℃ and 180 rpm. The mass ratio of bamboo slices to white rot fungus is 3:1, 5 g / L of Giant Dragon Bamboo powder is added to the solution, and it is cultured in a shaker for 30 days. After white rot fungus treatment, the bamboo slices are dried.

[0050] Preparation of bamboo-based composite materials:

[0051] Drying: Bamboo strips treated with white rot fungus were dried at 60℃ for 6 hours;

[0052] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0053] Paving: Lay three layers of bamboo strips along the grain;

[0054] Hot pressing: The laid bamboo strips are hot-pressed at 150℃ and 5.0MPa for 10 minutes to obtain the bamboo-based composite material of Giant Dragon Bamboo based on white rot fungus pretreatment modification.

[0055] Example 3

[0056] The preparation method of bamboo-based composite material modified by white-rot fungi in this embodiment includes:

[0057] Pretreatment modification of Giant Dragon Bamboo with white rot fungus: The white rot fungus is *Amanita muscaria*, the thickness of Giant Dragon Bamboo slices is 1.0 mm, the mass ratio of Giant Dragon Bamboo slices to sterile water is 1:20, and it is cultured in a shaker at 28℃ and 180 rpm. The mass ratio of bamboo slices to white rot fungus is 3:1, 5 g / L of Giant Dragon Bamboo powder is added to the solution, and it is cultured in a shaker for 30 days. After white rot fungus treatment, the bamboo slices are dried.

[0058] Preparation of bamboo-based composite materials:

[0059] Drying: Bamboo strips treated with white rot fungus were dried at 105℃ for 4 hours;

[0060] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0061] Paving: Lay three layers of bamboo strips along the grain;

[0062] Hot pressing: The laid bamboo strips are hot-pressed at 150℃ and 5.0MPa for 10 minutes to obtain the bamboo-based composite material of Giant Dragon Bamboo based on white rot fungus pretreatment modification.

[0063] Example 4

[0064] The preparation method of bamboo-based composite material modified by white-rot fungi in this embodiment includes:

[0065] Pretreatment modification of Giant Dragon Bamboo with white rot fungus: The white rot fungus is *Amanita muscaria*, the thickness of Giant Dragon Bamboo slices is 1.2 mm, the mass ratio of Giant Dragon Bamboo slices to sterile water is 1:20, and it is cultured in a shaker at 28℃ and 180 rpm. The mass ratio of bamboo slices to white rot fungus is 3:1, 5 g / L of Giant Dragon Bamboo powder is added to the solution, and it is cultured in a shaker for 30 days. After white rot fungus treatment, the bamboo slices are dried.

[0066] Preparation of bamboo-based composite materials:

[0067] Drying: Bamboo strips treated with white rot fungus were dried at 60℃ for 6 hours;

[0068] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0069] Paving: Lay three layers of bamboo strips along the grain;

[0070] Hot pressing: The laid bamboo strips are hot-pressed at 150℃ and 5.0MPa for 10 minutes to obtain the bamboo-based composite material of Giant Dragon Bamboo based on white rot fungus pretreatment modification.

[0071] Example 5

[0072] The preparation method of bamboo-based composite material modified by white-rot fungi in this embodiment includes:

[0073] Pretreatment modification of Giant Dragon Bamboo with white rot fungus: The white rot fungus is *Amanita muscaria*, the thickness of Giant Dragon Bamboo slices is 1.5 mm, the mass ratio of Giant Dragon Bamboo slices to sterile water is 1:25, and it is cultured in a shaker at 28℃ and 150 rpm. The mass ratio of bamboo slices to white rot fungus is 1:1, 5 g / L of Giant Dragon Bamboo powder is added to the solution, and it is cultured in a shaker for 10 days. After white rot fungus treatment, the bamboo slices are dried.

[0074] Preparation of bamboo-based composite materials:

[0075] Drying: Bamboo strips treated with white rot fungus were dried at 60℃ for 6 hours;

[0076] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0077] Paving: Lay three layers of bamboo strips along the grain;

[0078] Hot pressing: The laid bamboo strips are hot-pressed at 160℃ and 5.0MPa for 10 minutes to obtain the bamboo-based composite material of Giant Dragon Bamboo modified by white rot fungus pretreatment.

[0079] Example 6

[0080] The preparation method of bamboo-based composite material modified by white-rot fungi in this embodiment includes:

[0081] Pretreatment modification of Giant Dragon Bamboo with white rot fungus: The white rot fungus is *Amanita muscaria*, the thickness of Giant Dragon Bamboo slices is 1.5 mm, the mass ratio of Giant Dragon Bamboo slices to sterile water is 1:25, and it is cultured in a shaker at 30℃ and 180 rpm. The mass ratio of bamboo slices to white rot fungus is 3:1, 5 g / L of Giant Dragon Bamboo powder is added to the solution, and it is cultured in a shaker for 30 days. After white rot fungus treatment, the bamboo slices are dried.

[0082] Preparation of bamboo-based composite materials:

[0083] Drying: Air-dry the bamboo strips treated with white rot fungus for 24 hours;

[0084] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0085] Paving: Lay three layers of bamboo strips along the grain;

[0086] Hot pressing: The laid bamboo strips are hot-pressed at 180℃ and 5.0MPa for 10 minutes to obtain the bamboo-based composite material of Giant Dragon Bamboo modified by white rot fungus pretreatment.

[0087] Comparative Example 1

[0088] The method for preparing the bamboo-based composite material in this embodiment includes:

[0089] Without pretreatment with white-rot fungi to modify the giant bamboo, and with bamboo strips 1.2 mm thick, bamboo-based composite materials were directly prepared.

[0090] Drying: Air-dry the bamboo slices of Giant Dragon Bamboo for 24 hours;

[0091] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0092] Paving: Lay three layers of bamboo strips along the grain;

[0093] Hot pressing: The laid bamboo strips are hot-pressed at 150℃ and 5.0MPa for 10 minutes to obtain bamboo-based composite materials prepared directly from giant bamboo.

[0094] Comparative Example 2

[0095] The method for preparing the bamboo-based composite material in this embodiment includes:

[0096] Pretreatment modification of Giant Dragon Bamboo with white rot fungus: The white rot fungus is *Amanita muscaria*, the thickness of Giant Dragon Bamboo slices is 1.0 mm, the mass ratio of Giant Dragon Bamboo slices to sterile water is 1:20, and it is cultured in a shaker at 25℃ and 150 rpm. The mass ratio of bamboo slices to white rot fungus is 1:1, and it is cultured in the shaker for 10 days. After white rot fungus treatment, the bamboo slices are dried.

[0097] Preparation of bamboo-based composite materials:

[0098] Drying: Air-dry the bamboo strips treated with white rot fungus for 24 hours;

[0099] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0100] Paving: Lay three layers of bamboo strips along the grain;

[0101] Hot pressing: The laid bamboo strips are hot-pressed at 150℃ and 5MPa for 10 minutes to obtain a bamboo-based composite material of Giant Dragon Bamboo based on white rot fungus pretreatment modification (no bamboo powder is added during the cultivation process).

[0102] Comparative Example 3

[0103] The method for preparing the bamboo-based composite material in this embodiment includes:

[0104] The white-rot fungus was used to modify the Giant Dragon Bamboo by pretreatment: the white-rot fungus was *Amanita muscaria*, the thickness of the Giant Dragon Bamboo slices was 1.2 mm, the mass ratio of the Giant Dragon Bamboo slices to sterile water was 1:20, and it was cultured in a shaker at 28℃ and 180 rpm. The mass ratio of the bamboo slices to the white-rot fungus was 3:1, and it was cultured in the shaker for 30 days. After the white-rot fungus treatment, the bamboo slices were dried.

[0105] Preparation of bamboo-based composite materials:

[0106] Drying: Air-dry the bamboo strips treated with white rot fungus for 24 hours;

[0107] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0108] Paving: Lay three layers of bamboo strips along the grain;

[0109] Hot pressing: The laid bamboo strips are hot-pressed at 150℃ and 5.0MPa for 10 minutes to obtain a bamboo-based composite material of Giant Dragon Bamboo based on white rot fungus pretreatment modification (no bamboo powder is added during the cultivation process).

[0110] Comparative Example 4

[0111] The method for preparing the bamboo-based composite material in this embodiment includes:

[0112] Pretreatment modification of Giant Dragon Bamboo with white rot fungus: The white rot fungus is *Amanita muscaria*, the thickness of Giant Dragon Bamboo slices is 1.5 mm, the mass ratio of Giant Dragon Bamboo slices to sterile water is 1:25, and it is cultured in a shaker at 28℃ and 150 rpm. The mass ratio of bamboo slices to white rot fungus is 1:1, and it is cultured in the shaker for 10 days. After white rot fungus treatment, the bamboo slices are dried.

[0113] Preparation of bamboo-based composite materials:

[0114] Drying: Bamboo strips treated with white rot fungus were dried at 60℃ for 6 hours;

[0115] Adhesive application: Apply commercially available urea-formaldehyde resin adhesive at a rate of 170 g / m². 2 ;

[0116] Paving: Lay three layers of bamboo strips along the grain;

[0117] Hot pressing: The laid bamboo strips are hot-pressed at 160℃ and 5.0MPa for 10 minutes to obtain a bamboo-based composite material of Giant Dragon Bamboo based on white rot fungus pretreatment modification (no bamboo powder is added during the cultivation process).

[0118] Figure 1(a) shows the changes in ligninase activity secreted by the white-rot fungus *Cyclocarya paliurus* during the modification of *Bamboo styracifolium* under the culture conditions of this invention (with the addition of 5 g / L *Bamboo styracifolium* powder). As can be seen from the figure, the laccase secreted by the white-rot fungus maintained high activity (above 200 U / ml) throughout the treatment period of 2-30 days. In contrast, the activities of manganese peroxidase and lignin peroxidase were lower (below 200 U / ml). This is very advantageous for achieving the purpose of the invention because the role of laccase is to break the side chains of phenolic structures, while manganese peroxidase and lignin peroxidase decompose phenolic lignin. Compared to (a), (b) shows the changes in ligninase activity secreted by the white-rot fungus *Cyclocarya paliurus* during the modification of *Bamboo styracifolium* under culture conditions without the addition of *Bamboo styracifolium* powder. As can be seen from the figure, during the culture period of 10-90 days, the activity of laccase is not high compared to the high activity of lignin peroxidase and manganese peroxidase. Especially at 30 days, the activities of lignin peroxidase and manganese peroxidase are much higher than that of laccase. Only at 60 days does the activity of laccase exceed 400 U / ml and is higher than that of lignin peroxidase and manganese peroxidase. However, the treatment time is 60 days, which is too long and inefficient. In addition, it will also lead to excessive degradation of the bamboo cell wall due to the long fungal action time, resulting in a decrease in the overall mechanical strength of the bamboo.

[0119] The objectives of this invention are (1) to break the side chains of lignin macromolecules, but not to degrade the aromatic ring structure of lignin, with the aim of degrading macromolecules into smaller molecules and simultaneously improving the reactivity of lignin; (2) to increase the relative cellulose content and crystallinity of bamboo. Furthermore, to prepare high-strength bamboo-based composite materials, bamboo cannot undergo excessive degradation. Figure 1 The comparative analysis results of (a) and (b) prove that the purpose of the invention can only be achieved under the control of the culture conditions of the present invention.

[0120] Figure 2(a) shows the changes in the activity of cellulase (endocerebrokinase and exocerebrokinase) and hemicellulase secreted by the white-rot fungus *Cyclocarya paliurus* during the modification of *Bamboo styracifolium* under the culture conditions of this invention (with the addition of 5 g / L *Bamboo styracifolium* powder). As can be seen from the figure, during the treatment period of 2-30 days, the activity of both cellulase and hemicellulase remained very low. Except for the second day when the activity was 45-50 U / ml, the activity of cellulase (endocerebrokinase and exocerebrokinase) and hemicellulase remained below or close to 20 U / ml during the period of 4-30 days. Compared with ligninase, whose activity remained above 200 U / ml, the cellulose in bamboo hardly changed under the condition of extremely low cellulase activity. Therefore, cellulose is not affected by fungi and degraded. This is consistent with the results in Tables 1 and 2 above. Cellulose mainly plays a supporting role for the cell wall in wood and bamboo, which is beneficial to the realization of the purpose of the invention.

[0121] Compared with (a), (b) shows the changes in the enzyme activities of cellulase (endonuclease and exonuclease) and hemicellulase secreted during the modification of *Bambusa multiplex* by the white-rot fungus *Bambusa multiplex* under culture conditions without the addition of *Bambusa multiplex* powder. As can be seen from the figure, the activity of exonuclease remained high throughout the culture period of 10-90 days. Highly active exonuclease can degrade the cellulose macromolecular chain, thereby destroying the crystalline part and causing a decrease in crystallinity. This reduces the mechanical properties of the bamboo and is not conducive to achieving the purpose of the invention.

[0122] therefore, Figure 1 (a) and (b) and Figure 2 The comparative analysis results of (a) and (b) prove that the purpose of the invention can only be better achieved under the control of the culture conditions of the present invention.

[0123] Figure 3 It is an X-ray photoelectron spectroscopy (XPS) analysis of the surface of bamboo. Figure 3 Figures (a), (b), (c), and (d) show the changes in the surface chemical properties of *Phyllostachys edulis* after 0, 10, 20, and 30 days of modification treatment using the white-rot fungus *Amanita muscaria*. The calculation results are shown in Table 3. XPS is highly sensitive to the state of the sample and can perform qualitative or semi-quantitative analysis of elements on solid surfaces. The main components of bamboo include carbon, hydrogen, and oxygen. Therefore, the structure of atomic clusters in bamboo can be determined by peak intensity and chemical changes, and the chemical properties of the bamboo surface can also be obtained. The unconvolution high-resolution XPS spectrum of the C1s peak in bamboo mainly corresponds to four types of carbon atoms, represented as C1-C4. The C1 component mainly comes from lignin and extracts, C2 is shown to mainly come from cellulose, C3 is assigned to cellulose, and C4 is ignored here because its content is very low.

[0124] Figure 3 The calculation results are listed in Table 3. Table 3 shows the changes in C(1s) content on the surface of *Phyllostachys edulis* after modification with the white-rot fungus *Phyllostachys edulis*. As can be seen from the table, the C1 content on the surface of *Phyllostachys edulis* without white-rot treatment is 35.08%, and the C2 content is 54.61%. After white-rot treatment, the C1 content on the surface of *Phyllostachys edulis* begins to decrease, while the C2 content shows an upward trend. When the modification time is 10, 20, and 30 days, the C1 content decreases to 30.38%, 28.56%, and 25.52%, respectively. Compared with C1, the C2 content increases to 64.00%, 62.11%, and 68.68%, respectively.

[0125] Bamboo is similar to wood, with its main chemical components being cellulose, hemicellulose, and lignin, and its main elemental composition being C, H, and O. Analyzing the state changes of carbon (C) is crucial in chemical property analysis. Understanding the position and intensity of absorption fronts reveals the bonding patterns of C atoms, thus allowing us to deduce the chemical structure and structural changes on the bamboo surface. C1 mainly originates from lignin and phenylpropane, while C2 consists of cellulose and hemicellulose. Therefore, it can be seen that with prolonged modification time, the lignin content in bamboo decreases due to degradation, leading to a relative increase in cellulose content. This increase in the relative cellulose content of bamboo is beneficial for achieving the invention's objective.

[0126] Figure 4 This paper analyzes the surface wettability of bamboo-based composite materials prepared after modification of *Phyllostachys edulis* by the white-rot fungus *Phyllostachys edulis* under the cultivation conditions of this invention. Surface wettability is analyzed by measuring the water contact angle. As shown in the figure, the water contact angle of the bamboo-based composite material prepared without white-rot fungus treatment is 99.125°, while the water contact angles of the bamboo-based composite material prepared after white-rot fungus modification are 88.625° (10 days), 85.525° (20 days), and 76.375° (30 days). The surface contact angle reflects the material's response to liquids in the material... The ease with which a liquid spreads, wets, and penetrates a material surface is determined by the contact angle. A larger contact angle indicates greater difficulty in these processes, while a smaller contact angle indicates greater ease. As shown in the figure, after treatment with white rot fungi, the contact angle of the bamboo surface decreases, signifying improved wettability. Enhanced wettability means that during the bonding process of composite materials, the adhesive's spreading and penetration on the bamboo surface will be improved. The adhesive will more easily penetrate into the bamboo, forming glue nails and improving the bonding quality and performance of the composite material. This, in turn, promotes the improvement of the composite material's mechanical properties.

[0127] Figure 5The results show the bonding strength of bamboo-based composite materials prepared by white-rot fungi-modified *Phyllostachys edulis*. As can be seen from the figure, the bonding strength of the composite material increases after white-rot fungi modification. This is because the white-rot fungi improve the wettability of the bamboo surface, making it easier for the adhesive to spread and wet the bamboo surface and penetrate into the bamboo interior. This facilitates the formation of adhesive nails during hot pressing, improving the bonding quality and performance of the composite material. On the other hand, the highly active laccase causes lignin side chains to break, degrading large molecules into smaller molecules and increasing reactivity. During bonding, small-molecule lignin and hemicellulose also act as adhesives, resulting in a tighter bond between cellulose, hemicellulose, lignin, and the adhesive. This improves the bonding quality and performance of the composite material, which in turn positively impacts its bonding strength. Therefore, the bonding strength of the composite material significantly increased from 4.88 MPa to 6.23 MPa, an increase of 127.7%.

[0128] Figure 6 The figures show the test results for the tensile strength of Giant Dragon Bamboo and bamboo-based composites. As can be seen from the graph, the tensile strength of both Giant Dragon Bamboo and bamboo-based composites increased after white-rot fungal modification treatment. For Giant Dragon Bamboo, the increase in tensile strength is due to the degradation of lignin leading to a relatively higher cellulose content and increased crystallinity, which is beneficial for improving mechanical strength. Therefore, the tensile strength of Giant Dragon Bamboo increased from 142.08 MPa to 191.20 MPa, an increase of 134.6%.

[0129] For bamboo-based composite materials, on the one hand, the action of fungi increases the surface wettability of bamboo, making it easier for adhesives to spread and wet the bamboo surface and penetrate into the bamboo interior. This facilitates the formation of adhesive nails during hot pressing, improving the bonding quality and performance of the composite material and promoting its mechanical properties. On the other hand, under the action of highly active laccase, lignin side chains break, and large molecules degrade into smaller molecules, while reactivity is enhanced. During the bonding process, small lignin and hemicellulose molecules also act as adhesives, allowing cellulose and hemicellulose to bond together. The bonding between cellulose, lignin, and adhesives is more compact, thus improving the bonding quality and performance of the composite material. In addition, during the white-rot fungus process, the cellulose content in bamboo is relatively increased due to the consistently low activity of cellulase, and the crystallinity also increases. Since crystallinity is positively correlated with the mechanical properties of materials, this also plays a positive role in improving the mechanical strength of the composite material. As a result, the tensile strength of the composite material is significantly improved, increasing from 195.83 MPa to 253.58 MPa, an increase of 129.5%.

[0130] Figure 7 This image shows the changes in the cell walls of *Phyllostachys edulis* after modification with white-rot fungi. As can be observed, untreated *Phyllostachys edulis* cells are densely packed with smooth, flat inner cell walls. After modification, the smoothness of the inner cell walls decreases, cracks appear, and the cell pores enlarge. Especially after 20 and 30 days of white-rot treatment, obvious cracks and pores are clearly visible in the inner cell walls, and the cell arrangement becomes looser. At 30 days of treatment, increased cell wall damage is clearly visible, and fungal hyphae are clearly visible inside the cells. Therefore, the enlarged cell pores under the influence of white-rot fungi positively impact the wettability of bamboo, promote the penetration of adhesives into the bamboo, and improve bonding quality.

[0131] Figure 8 The images show the bonding interface of bamboo-based composites prepared by white-rot fungi modification. As can be observed, the bonding interface of the untreated *Gymnocypris chinensis* bamboo-based composite is clear, with visible glue lines due to poor adhesive penetration into the bamboo. In contrast, the glue lines in the white-rot-modified *Gymnocypris chinensis* composite are blurred, especially in the composites treated for 20 and 30 days. It can be seen that the adhesive has penetrated into the adjacent bamboo cell walls near the glue layer. This is because the fungus increases the wettability of the bamboo surface, making it easier for the adhesive to spread and wet the bamboo surface and penetrate into the bamboo interior. This results in glue nails forming during hot pressing, improving the bonding quality and performance of the composite, which also promotes the improvement of the composite's mechanical properties.

[0132] Table 1 Comparison of process conditions and results between the examples and the comparative examples

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[0134]

[0135] Table 2 Chemical composition of Bamboo stalks modified with white-rot fungi

[0136]

[0137] Table 2 shows the changes in chemical composition of *Phyllostachys edulis* after modification with the white-rot fungus *Amanita muscaria*. The table shows that the cellulose content of *Phyllostachys edulis* without white-rot treatment was 40.51%, and the lignin content was 28.93%. After white-rot treatment, the cellulose content increased, while the lignin content decreased. At modification times of 10, 20, and 30 days, the cellulose content was 42.94%, 45.08%, and 47.10%, respectively, while the lignin content decreased to 28.31%, 27.67%, and 26.79%. This indicates that as the modification time increased, lignin in the bamboo was degraded, but cellulose remained unchanged, resulting in a relatively higher cellulose content. Cellulose mainly plays a supporting role in the cell walls of bamboo and wood, therefore, the increase in the relative cellulose content of bamboo is beneficial to achieving the invention's objective.

[0138] Table 3. C(1s) content on the surface of *Phyllostachys edulis* after modification with white-rot fungi.

[0139]

[0140]

[0141] Table 4. Crystallinity of Bamboo Shoots after modification with the white-rot fungus *Corydalis fasciatus*.

[0142] 0 28.41 10 29.68 20 30.62 30 31.01

[0143] Table 4 shows the changes in crystallinity of *Phyllostachys edulis* after modification with the white-rot fungus *Amanita muscaria*. The table shows that the crystallinity of *Phyllostachys edulis* without white-rot treatment was 28.41%. After modification, the crystallinity of the bamboo increased. At modification times of 10, 20, and 30 days, the crystallinity was 29.68%, 30.62%, and 31.01%, respectively. This indicates that the crystallinity increases with the extension of modification time. This is because lignin is degraded. Lignin molecules are amorphous substances, and partial degradation leads to a relative increase in cellulose content, thus increasing crystallinity. Therefore, pretreatment modification of *Phyllostachys edulis* with white-rot fungus within 10-30 days will increase the crystallinity. Crystallinity is positively correlated with mechanical properties, thus improving mechanical properties.

[0144] Table 5 Density of composite materials prepared after modification with white-rot fungi

[0145]

[0146] Table 5 shows the density changes of bamboo-based composite materials prepared from *Phyllostachys edulis* after modification with the white-rot fungus *Phyllostachys edulis*. The table shows that the density of the bamboo-based composite material from *Phyllostachys edulis* without white-rot treatment was 0.836. After white-rot treatment, the density of the bamboo-based composite material began to increase. At modification times of 10, 20, and 30 days, the densities were 0.947, 1.070, and 1.009, respectively. This indicates that the density of the bamboo-based composite material gradually increased with the extension of modification time, reaching 1.21 times the initial density at 30 days. The mechanical strength of the composite material is positively correlated with density; as density increases, the mechanical strength of the composite material also increases. Therefore, it can be seen that pretreatment modification of *Phyllostachys edulis* with white-rot fungus improves the mechanical strength of the bamboo-based composite material.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a white-rot fungus-modified bamboo-based composite material, characterized by comprising the following steps: Including modification treatment: ​ Prepare bamboo chips of Giant Dragon Bamboo and sterile water at a mass ratio of 1:20-1:25, and white rot fungus at a mass ratio of 1:1-3:

1. Add the white rot fungus and bamboo chips to the sterile water, and then add 5g / L of Giant Dragon Bamboo powder to the solution. Incubate in a shaker at 25℃-30℃ and 150-180 rpm for 10-30 days. After white rot fungus treatment, dry the bamboo chips.

2. The method of claim 1, wherein: The white-rot fungus is *Amanita muscaria*.

3. The method of claim 1, wherein: The thickness of the bamboo strips from Giant Dragon Bamboo is 0.8-1.5mm.

4. The method of claim 1, wherein: The mass ratio of bamboo strips to sterile water was 1:

20. The culture conditions were 25℃ and 150 rpm and 28℃ and 180 rpm in shakers. The mass ratio of bamboo strips to white rot fungus was 3:

1. 5 g / L of giant bamboo powder was added to the solution. After 30 days of culture in shakers, the bamboo strips were taken out and dried.

5. A method for preparing a white-rot fungus-modified bamboo-based composite material, characterized by comprising the following steps: include: ​ Drying: The bamboo strips modified by the white-rot fungus are air-dried or oven-dried; the modification treatment is carried out according to the preparation method described in any one of claims 1-4; Apply adhesive: Apply commercially available urea-formaldehyde resin adhesive; Paving: Lay three layers of bamboo strips along the grain; Hot pressing: The laid bamboo strips are hot-pressed at 130-180℃ and 1.5-5.0MPa for 6-10 minutes to obtain a bamboo-based composite material modified by white rot fungi.

6. The method of claim 5, wherein: Air-dry the bamboo strips for 24 hours or dry them at 60℃ for 6 hours.

7. The method of claim 5, wherein: In the gluing process, the amount of glue applied was 170 g / m 2 .

8. The method of claim 5, wherein: After laying, the bamboo strips are hot-pressed at 130-180℃ and 1.5-5.0MPa for 6-10 minutes.

9. A white-rot fungus-modified bamboo-based composite material, characterized by: Prepared by the preparation method according to any one of claims 5-8.

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