Composite filling reinforcing agent for unearthed woodware in semi-arid environment as well as preparation method and application of composite filling reinforcing agent

Abstract

The invention discloses a composite filling reinforcing agent for unearthed woodware in a semi-arid environment as well as a preparation method and application of the composite filling reinforcing agent, and belongs to the technical field of reinforcing materials for rotten wood cultural relics in the semi-arid environment. The composite filling reinforcing agent for the unearthed woodware in the semi-arid environment comprises the following components: a carboxylated cellulose nanofiber solution, a polyanionic cellulose solution and a carboxymethyl chitosan solution. The three cellulose derivatives are used as reinforcing agents, and isopropanol is selected as a penetration enhancer. The problem of permeability of the carboxylated cellulose nanofiber, the polyanionic cellulose and the carboxymethyl chitosan is solved, and the carboxylated cellulose nanofiber, the polyanionic cellulose and the carboxymethyl chitosan can be better brought into a cavity generated by the rotten wood, so that the permeability of the reinforcing agent is enhanced; in addition, the color difference of the reinforcing agent belongs to an acceptable range, and possibility is provided for rescue protection of unearthed rotten wood cultural relics in semi-arid regions.

Description

Technical Field

[0001] The invention belongs to the technical field of reinforcing materials for rotten wood cultural relics unearthed in semi-arid environments, and more particularly relates to a composite filling reinforcing agent for wooden artifacts unearthed in semi-arid environments, and a preparation method and application thereof. Background Art

[0002] Professional research on ancient wood, particularly water-saturated wood, has been highly successful, contributing significantly to the preservation of cultural relics. However, our research remains in-depth and specialized, particularly for ancient wood excavated in semi-arid regions. Furthermore, while currently effective, commonly used wood reinforcement methods and chemical agents often have limitations, requiring further research to identify optimal materials.

[0003] Research on reinforcing materials for wooden cultural relics has always been a key and challenging aspect of cultural relic preservation. Wood is composed of 40-50% cellulose, 10-30% hemicellulose, and 20-30% lignin. These polysaccharides undergo changes under the influence of bacteria, oxygen, and other factors, disrupting the wood's original structure, reducing its basic density, and increasing its corrosion rate. This can manifest in wooden cultural relics as decay, damage, breakage, cracks, deformation, discoloration, and microbial damage, compromising their value.

[0004] Most artifacts unearthed from tombs have been exposed to groundwater. During contact with external water, the acids and alkalis in the water, as well as the action of microorganisms, severely degrade the cellulose and hemicellulose in these wooden artifacts. This leads to increased lignin and ash content, darkening the wood's color and reducing its strength. Once unearthed, these wooden artifacts come into contact with air and lose moisture, rendering their cell walls unable to provide support. This causes them to decay or even pulverize. Current research focuses on the characterization and reinforcement of water-saturated wooden artifacts. These methods generally involve first dehydrating the artifact and then increasing its structural strength. However, research on reinforcement materials for dried wooden artifacts is relatively limited. In the 19th century, the inorganic water glass (Na2SiO3) was used for wood reinforcement. Organic natural products such as natural glues, oils, waxes, resins, tung oil, beeswax, rosin, and sucrose have also been used as reinforcement treatments for dried wood. With the continuous enrichment of materials, various organic synthetic materials are also used for the impregnation reinforcement of dried wooden cultural relics and have achieved certain results, such as: polyvinyl butyral, styrene, methyl methacrylate, epoxy resin, etc. Although these materials have good bonding strength, they are easily yellowed by light aging outdoors and are difficult to remove after aging. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite filling reinforcement agent for wooden objects excavated in semi-arid environments, a preparation method and application thereof, so as to solve the problems existing in existing reinforcement materials.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a composite filling and reinforcing agent for wooden objects unearthed in semi-arid environments, comprising the following components: a carboxylated cellulose nanofiber solution, a polyanionic cellulose solution, and a carboxymethyl chitosan solution;

[0008] The volume ratio of the carboxylated cellulose nanofiber solution, the polyanionic cellulose solution, and the carboxymethyl chitosan solution is 1:1:1.

[0009] Preferably, the carboxylated cellulose nanofiber solution is an aqueous solution of carboxylated cellulose nanofibers; the polyanionic cellulose solution is an aqueous solution of polyanionic cellulose; and the carboxymethyl chitosan solution is an aqueous solution of carboxymethyl chitosan.

[0010] Preferably, the concentrations of the carboxylated cellulose nanofiber solution, the polyanionic cellulose solution and the carboxymethyl chitosan solution are independently 1-5%.

[0011] Preferably, the carboxylated cellulose nanofibers in the carboxylated cellulose nanofiber solution have a diameter of 4 to 10 nm and a length of 200 nm.

[0012] The second technical solution of the present invention is to provide a method for preparing the composite filling and reinforcing agent for wooden objects excavated in semi-arid environments, comprising the following steps:

[0013] Carboxylated cellulose nanofibers, polyanionic cellulose and carboxymethyl chitosan are added to water and dissolved respectively to obtain carboxylated cellulose nanofiber solution, polyanionic cellulose solution and carboxymethyl chitosan solution respectively. The three solutions are then mixed in equal volumes and a solvent is added to obtain a composite filling and reinforcement agent for wooden objects unearthed in semi-arid environments.

[0014] Preferably, the solvent comprises water and isopropyl alcohol.

[0015] Preferably, the solvent and the carboxylated cellulose nanofiber solution are in equal volumes.

[0016] The third technical solution of the present invention is to provide the application of the composite filling and reinforcing agent for wooden articles unearthed in semi-arid environments in the reinforcement of decayed wood.

[0017] A fourth technical solution of the present invention provides a method for reinforcing rotten wood cultural relics, comprising the following steps:

[0018] The composite filling and reinforcing agent for wooden artifacts unearthed in semi-arid environments is sprayed on the surface of rotten wooden artifacts for reinforcement.

[0019] Preferably, the number of reinforcements is ≥1.

[0020] The present invention discloses the following technical effects:

[0021] The present invention adopts carboxylated cellulose nanofiber, polyanionic cellulose, carboxymethyl chitosan, carries out a series of proportioning combinations, is dissolved by distilled water, and is combined into a composite filling reinforcement agent. Although the rotten wood cultural relics reinforced with carboxylated cellulose nanofiber and polyanionic cellulose alone have a certain strength, the reinforcement effect is poor, the corrosion resistance is poor and it is easy to become brittle. The carboxymethyl chitosan used in the present invention can be used as a cross-linking agent and adhesive, and can form a tough film, which can make up for the shortcomings of carboxylated cellulose nanofiber and polyanionic cellulose; using isopropyl alcohol as a penetration enhancer, carboxylated cellulose nanofiber, polyanionic cellulose and carboxymethyl chitosan can be better brought into the cavity produced by the rotten wood cultural relics. After the solvent evaporates, the mixture composed of carboxylated cellulose nanofiber, polyanionic cellulose and carboxymethyl chitosan can play a supporting and cross-linking role, thereby obtaining a better reinforcement effect. The composite filling reinforcement agent of the present invention has good permeability, can be applied to wood reinforcement, and the color difference is also within an acceptable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the experimental process for screening candidate reinforcement materials.

[0023] Figure 2 Schematic diagram of the mechanical properties experimental process of the composite filling and reinforcing agent of Example 3;

[0024] Figure 3 Schematic diagram of the film-forming property experimental process of the composite filling and reinforcing agent of Example 3;

[0025] Figure 4 Schematic diagram of the mechanical properties test results of the composite filling and reinforcing agent of Example 3;

[0026] Figure 5 Schematic diagram of the experimental results of penetrant addition to the composite filling and reinforcing agent of Example 3, wherein the left figure shows the experimental results before the addition of 10%, 20%, and 30% penetrant (isopropyl alcohol), from left to right, and the right figure shows the experimental results after the addition of 10%, 20%, and 30% penetrant (isopropyl alcohol), from left to right, in air drying;

[0027] Figure 6 Schematic diagram of the ultra-depth-of-field microscopy of the film surface of the composite filling and reinforcing agent of Example 3, wherein the left figure is before the composite filling and reinforcing agent is added, and the right figure is after the composite filling and reinforcing agent is added;

[0028] Figure 7 Schematic diagram of the surface scanning electron microscope of wood before and after being reinforced with the composite filling reinforcement agent of Example 3, wherein the upper figure is before the addition of the composite filling reinforcement agent, and the lower figure is after the addition of the composite filling reinforcement agent;

[0029] Figure 8 is the water contact angle of the wood after being reinforced with the composite filling and reinforcement agent of Example 3;

[0030] Figure 9 Comparison of the cumulative intrusion volume and pore diameter of the wood after being reinforced with the composite filling reinforcement agent of Example 3;

[0031] Figure 10 Comparison of the cumulative pore area and pore diameter of the wood after being reinforced with the composite filling and reinforcement agent of Example 3;

[0032] Figure 11 This is an infrared spectrum of the composite filling and reinforcing agent of Example 3 and its components, wherein 1 is nanocellulose, 2 is carboxymethyl chitosan, 3 is polyanionic cellulose, and 4 is the composite filling and reinforcing agent of Example 3;

[0033] Figure 12 These are infrared spectra of wood before and after being reinforced with the composite filling reinforcement agent of Example 3, where 6 is the wood before reinforcement and 7 is the wood after reinforcement. DETAILED DESCRIPTION

[0034] The present invention provides a composite filling and reinforcing agent for wooden objects unearthed in semi-arid environments, comprising the following components: a carboxylated cellulose nanofiber solution, a polyanionic cellulose solution, and a carboxymethyl chitosan solution;

[0035] The volume ratio of the carboxylated cellulose nanofiber solution, the polyanionic cellulose solution, and the carboxymethyl chitosan solution is 1:1:1.

[0036] The main characteristics of the composite material composed of carboxylated cellulose nanofibers, polyanionic cellulose and other elements used in the present invention are strong stability, dispersibility, permeability, etc. The results show that there is a hydrogen bonding effect between the three components. Moreover, after the wood is reinforced, the water in the composite gel evaporates, and the hydrogel also forms hydrogen bonds with the original wood, which plays a supporting role and makes the internal network structure of the wood more dense.

[0037] In the present invention, the carboxylated cellulose nanofiber solution is an aqueous solution of carboxylated cellulose nanofibers; the polyanionic cellulose solution is an aqueous solution of polyanionic cellulose; and the carboxymethyl chitosan solution is.

[0038] In the present invention, the concentrations of the carboxylated cellulose nanofiber solution, the polyanionic cellulose solution and the carboxymethyl chitosan solution are independently preferably 1-5%, and further independently selected to be 1%, 2%, 3%, 4% or 5%.

[0039] In the present invention, the carboxylated cellulose nanofibers in the carboxylated cellulose nanofiber solution have a diameter of 4 to 10 nm and a length of 200 nm.

[0040] The present invention also provides a method for preparing the composite filling and reinforcing agent for wooden objects excavated in semi-arid environments, comprising the following steps:

[0041] Carboxylated cellulose nanofibers, polyanionic cellulose and carboxymethyl chitosan are added to water and dissolved respectively to obtain carboxylated cellulose nanofiber solution, polyanionic cellulose solution and carboxymethyl chitosan solution respectively. The three solutions are then mixed in equal volumes and a solvent is added to obtain a composite filling and reinforcement agent for wooden objects unearthed in semi-arid environments.

[0042] In the present invention, the solvent includes water and isopropyl alcohol.

[0043] In the present invention, the solvent and the carboxylated cellulose nanofiber solution are equal in volume.

[0044] The present invention also provides the use of the composite filling and reinforcing agent for wooden articles unearthed in a semi-arid environment in reinforcing rotten wood.

[0045] The present invention also provides a method for reinforcing rotten wood cultural relics, comprising the following steps:

[0046] The composite filling and reinforcing agent for wooden artifacts unearthed in semi-arid environments is sprayed on the surface of rotten wooden artifacts for reinforcement.

[0047] In the present invention, the number of reinforcements is ≥ 1, more preferably 1 to 10, and even more preferably 3.

[0048] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0049] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0050] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0051] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0052] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0053] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0054] Unless otherwise specified, the raw materials used in the following examples of the present invention are all commercially available products, and the sources of the commercially available products do not affect the technical effects of the present invention.

[0055] Example 1

[0056] This embodiment provides a composite filling and reinforcement agent for wooden objects unearthed in semi-arid environments, comprising carboxylated cellulose nanofibers at a concentration of 1%, a polyanionic cellulose solution, and carboxymethyl chitosan, wherein the volume ratio of the carboxylated cellulose nanofibers, the polyanionic cellulose solution, and the carboxymethyl chitosan solution is 1:1:1.

[0057] The preparation method of the composite filling and reinforcing agent comprises the following steps:

[0058] Carboxylated cellulose nanofibers, polyanionic cellulose solution, and carboxymethyl chitosan solution are prepared separately and then evenly mixed, and equal volumes of distilled water and isopropyl alcohol are added to obtain a composite filling and reinforcing agent.

[0059] Example 2

[0060] This embodiment provides a composite filling and reinforcement agent for wooden objects unearthed in semi-arid environments, comprising carboxylated cellulose nanofibers at a concentration of 3%, a polyanionic cellulose solution, and carboxymethyl chitosan, wherein the volume ratio of the carboxylated cellulose nanofibers, the polyanionic cellulose solution, and the carboxymethyl chitosan solution is 1:1:1.

[0061] The preparation method of the composite filling and reinforcing agent comprises the following steps:

[0062] Carboxylated cellulose nanofibers, polyanionic cellulose solution, and carboxymethyl chitosan solution are prepared separately and then evenly mixed, and equal volumes of distilled water and isopropyl alcohol are added to obtain a composite filling and reinforcing agent.

[0063] Example 3

[0064] This embodiment provides a composite filling and reinforcement agent for wooden objects unearthed in semi-arid environments, comprising 4% carboxylated cellulose nanofibers, a polyanionic cellulose solution, and 5% carboxymethyl chitosan, wherein the volume ratio of the carboxylated cellulose nanofibers, the polyanionic cellulose solution, and the carboxymethyl chitosan solution is 1:1:1.

[0065] The preparation method of the composite filling and reinforcing agent comprises the following steps:

[0066] Carboxylated cellulose nanofibers, polyanionic cellulose solution, and carboxymethyl chitosan solution are prepared separately and then evenly mixed, and equal volumes of distilled water and isopropyl alcohol are added to obtain a composite filling and reinforcing agent.

[0067] Performance testing:

[0068] 1. Preliminary selection of reinforcement materials:

[0069] Table 1 Solubility and acidity and alkalinity screening results

[0070]

[0071]

[0072] The screening results in Table 1 show that methylcellulose, highly substituted hydroxypropyl cellulose, polyanionic cellulose, carboxymethyl cellulose, and carboxylated cellulose nanofibers are all soluble in water, with transparent, neutral aqueous solutions. Therefore, they were selected as candidate reinforcement materials for the next step of screening. However, only two of these materials were soluble in ethanol, and the data available were limited, making them unresearchable. Carboxymethyl chitosan is soluble in water, and its aqueous solution is alkaline. Based on the mechanism of wood decay, the decay process produces acidic substances. The alkaline nature of the reinforcement agent can neutralize these acidic substances and slow the decay process.

[0073] 2. Film mechanical properties test:

[0074] Mechanical properties of single component films:

[0075] According to the screening results in Table 1, the above aqueous solution with the same concentration (3%) was used to test the mechanical properties of the single-component film. The test results are shown in Table 2.

[0076] Table 2 Mechanical properties of single components

[0077]

[0078]

[0079] Based on the above experimental results, methylcellulose, highly substituted hydroxypropyl cellulose, carboxymethyl cellulose, and carboxylated cellulose nanofibers (diameter: 50nm, length 1-3μm) have high viscosities at the same concentration, which prevent bubbles from escaping the solution, resulting in slow film formation and an uneven film surface. Their maximum force and tensile strength cannot be accurately measured (or cannot be measured), making them excluded as reinforcement components for further testing. However, polyanionic cellulose, carboxylated cellulose nanofibers (diameter: 4-10nm, length 200nm), and carboxymethyl chitosan have lower viscosities, uniform film surfaces, and stable properties after film formation, making them potential candidates for reinforcement components. Film-forming properties are formed by particle aggregation, and good film-forming properties reflect the ability of particles to aggregate, which can be expressed as adhesion. Only protective materials with good adhesion can reinforce aging areas of cultural relics. Materials with good film-forming properties are considered preferred for use as protective materials.

[0080] The mechanical properties of polyanionic cellulose, carboxylated cellulose nanofibers (diameter: 4-10 nm, length 200 nm), and carboxymethyl chitosan at different concentrations were tested. The test results are shown in Table 3.

[0081] Table 3 Relationship between different concentrations of carboxylated cellulose nanofibers (diameter: 4-10 nm, length 200 nm), polyanionic cellulose and carboxymethyl chitosan and maximum force and tensile strength

[0082]

[0083] The table above shows the maximum force and tensile strength exhibited by carboxylated cellulose nanofibers, polyanionic cellulose, and carboxymethyl chitosan at different concentrations. As the concentration of these three materials changes, their mechanical properties generally show a trend of first increasing and then decreasing. When the concentration reaches its maximum value, the maximum force and tensile strength of these three materials do not reach their peak value, but instead decrease. This phenomenon is likely related to the increase in solution viscosity caused by the increase in solution concentration. As the solution viscosity increases, the thickness of the film produced may increase accordingly, which in turn leads to increased brittleness and decreased uniformity of the film, ultimately affecting its mechanical properties.

[0084] Take the above three alternative reinforcement agents and make different concentration ratios, a total of 80 different concentration ratios are obtained. The experimental process is as follows Figures 1 to 4The experimental results show that the optimal ratio is 4:5:4, which is the concentration ratio of carboxylated cellulose nanofibers (diameter: 4-10nm, length 200nm): carboxymethyl chitosan: polyanionic cellulose. The maximum force average value under this ratio is 78.760N, and the average tensile strength is 47.13N / mm 2 (like Figure 2 shown).

[0085] 3. Reinforcement agent permeability test:

[0086] When the aforementioned reinforcing agent was applied to the wood sample, it was found that the reinforcing agent did not penetrate well. Therefore, it was necessary to add a surfactant to the reinforcing agent to promote its penetration. Alternative penetrants are listed in Table 4.

[0087] Table 4 Screening results of alternative penetration enhancers

[0088]

[0089] Table 4 shows that n-propanol and isopropanol can promote the penetration of the reinforcement agent very well, and the penetration effect is good. Since isopropanol is less toxic, has a lower boiling point, a smaller surface tension, and has better solubility than n-propanol, isopropanol is selected as the final penetration enhancer, and its addition amount is tested. The test results are as follows: Figure 5 As shown in the left figure, the amount of isopropyl alcohol added from left to right is 10%, 20% and 30% respectively. It can be clearly seen from the figure that the reinforcement with an addition of 30% has the best permeability. The right figure shows the reinforcement after it has dried. It can be clearly seen that the color difference of the wood before and after reinforcement is small ( Figure 5 ), and finally 30% of isopropyl alcohol was added.

[0090] 4. Color difference analysis:

[0091] The rotten wood samples from different parts were placed on a colorimeter and their initial values ​​were recorded. The composite filling and reinforcing agents prepared in Examples 1 to 3 were then applied to the surface of the samples, placed at room temperature, and dried in the shade. The values ​​were measured again and the color difference was calculated. The statistical results of the color difference values ​​are shown in Table 5.

[0092] Table 5 Color difference statistics of the composite filling and reinforcing agents of coating Example 1, Example 2, and Example 3

[0093]

[0094] As shown in Table 5, the color difference of the composite filling and reinforcing agent of Example 1 is 1.9, the color difference of the composite filling and reinforcing agent of Example 2 is 1.8, and the color difference of the composite filling and reinforcing agent of Example 3 is 1.3. The color change of the sample after reinforcement is acceptable (the corresponding relationship between the △E value and the color change is shown in Table 6).

[0095] Table 6 Correspondence between △E value and color change

[0096] Serial number Color Change ΔE 1 trace 0～0.5 2 slight 0.5～1.5 3 Can feel 1.5～3.0 4 obvious 3.0～6.0 5 Very big 6.0～12.0 6 Completely different >12.0

[0097] 5. Scanning electron microscope:

[0098] The mixed cellulose aqueous solution penetrates and diffuses on the wood surface due to capillary action. During the film-forming process, the water evaporates and the particles in the solution form a densely filled protective layer on the surface. The cellulose protective material inside the substrate fills the pores of the substrate. After the residual water between the particles inside the wood evaporates further, the particles undergo plastic deformation and fuse with each other due to the capillary pressure of the water, forming a three-dimensional network structure. The microscopic morphology of the film formed by the cellulose protective material on the wood can be observed through a microscope. It can be observed that the film density is continuous and dense (such as Figure 6 ), making the wood more firmly connected to the protective layer on its surface (as shown Figure 7 shown).

[0099] Reinforcement of simulated rotten wood samples: The composite filling reinforcement agent of Example 3 was used to reinforce simulated adobe samples. The specific experimental content was as follows: simulated rotten wood samples of the same specifications were prepared, and the composite filling reinforcement agent was added drop by drop to the simulated rotten wood samples with a dropper. The parallel experiment was carried out three times, and each sample was reinforced only once. After reinforcement, its compressive strength was measured. The average transverse pressure of the wood sample before reinforcement was 35.02N, and the average compressive strength was 0.8645N / mm 2 The average vertical grain pressure is 81.42N, and the average compressive strength is 0.4038N / mm 2 .

[0100] After reinforcement, the average transverse pressure is 277.320N, and the average compressive strength is 2.49N / mm 2 The average vertical grain pressure is 530.842N, and the average compressive strength is 3.61N / mm 2 .

[0101] Before and after reinforcement, the transverse pressure increased by about 8 times, and the average compressive strength increased by 3 times; the vertical pressure increased by 6.5 times, and the average compressive strength increased by 8.9 times.

[0102] 6. Contact angle

[0103] use DSA100 contact angle goniometer (German The water contact angle of the surface bubble was measured by the sessile water drop method. All contact angles were measured at least three times for each sample and the average was taken to ensure reproducibility.

[0104] After reinforcement with the reinforcement agent prepared in the optimal ratio (ie, Example 3), the water bubble contact angles measured on the rotten wood samples were 101° and 102.5° respectively (eg Figure 8 (shown). The substantial increase in contact angle demonstrates that the reinforcement treatment successfully enhanced the wood's surface hydrophobicity. The higher contact angle indicates that the reinforcement material effectively formed a protective layer on the wood's surface, reducing water absorption. This increased hydrophobicity benefits the wood's preservation and durability by preventing further water penetration, a major factor in wood degradation. By improving water resistance, the reinforcement treatment contributes to the wood's long-term stability, making it more suitable for use in high-humidity environments, such as those in protective applications and the packaging industry.

[0105] 7. Porosity

[0106] Pore ​​size distribution was determined using an AutoPore 9620 mercury intrusion porosimeter (Micromeritics, USA). This method is based on the Washburn equation (Equation 1), which relates applied pressure to pore radius, assuming mercury is non-wetting (contact angle greater than 90°). As pressure increases, mercury is forced into smaller pores, allowing pore size and volume to be derived from the intrusion data. This instrument operates at pressures up to 400 MPa and can measure pore diameters ranging from 0.003 to 950 μm.

[0107] Pr=-2γcosθ Formula 1

[0108] Where P is the applied pressure, γ is the surface tension of mercury, θ is the contact angle between mercury and the solid surface, and r is the pore radius.

[0109] Experimental results show that treatment with the curing agent prepared at the optimal ratio (i.e., Example 3) significantly reduced the porosity of the decayed wood. The porosity of the treated wood reached 73.41%, a significant decrease. This indicates that the curing agent effectively filled the pores, increasing the wood's density and structural stability. This change reflects the curing agent's penetration and structural modification, improving the wood's physical properties and durability.

[0110] Further analysis showed that the pore size distribution of the treated wood became more concentrated, with a decrease in the number of larger pore sizes, especially in the larger pore size range. Figure 9 and Figure 10 These results are corroborated by the cumulative pore volume and pore size histograms in the Figure 2 , which clearly show significant differences in the pore structure of the wood before and after treatment. Overall, the use of a curing agent not only significantly reduced the porosity of decayed wood but also improved the uniformity of its pore structure, providing theoretical support for the durability and other applications of treated wood.

[0111] 8. Infrared spectroscopy

[0112] The wood treated with the curing agent prepared in the optimal ratio (i.e., Example 3) was subjected to infrared spectroscopy. Nicolet Nexus-6700 Fourier transform infrared spectrometer (Thermo Corporation) was used. The sample and background were scanned 32 times; the wave number range was 4000-400 cm -1 , resolution 4cm -1 ; Measurement accessories: ATR; Single crystal: Zn-Se.

[0113] In infrared spectroscopy, the wave number is 3282 cm -1 The corresponding OH stretching vibration represents the characteristic structure of acids and esters; the wave number is 2919 cm -1 The corresponding vibration is CH stretching, which represents the alkyl characteristics; the wave number is 1025 cm -1 The corresponding vibration is the CO stretching vibration, which represents the carbonyl characteristic ( Figure 11 and Figure 12 ). In addition, the wave number 1629cm -1 The peak corresponding to the C=O stretching vibration is observed from 1629 cm -1 Reduced to 1590cm -1 ( Figure 12 This shift in wavenumber may be due to the formation of hydrogen bonds between oxygen atoms and adjacent hydrogen atoms in carbonyl compounds. This interaction may weaken the chemical bonds within the molecule, shifting the infrared absorption peak to a lower wavenumber, or the formation of hydrogen bonds may alter the interatomic interactions, lowering the vibrational frequency.

[0114] In the absence of changes in the wavenumbers of other functional groups, the decrease in the wavenumber of C=O may indicate that hydrogen bonds are formed between the reinforcement and the wood, thereby enhancing the adhesion between the reinforcement and the wood and thus improving the reinforcement effect.

[0115] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0116] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite filling and reinforcing agent for wood excavated in semi-arid environments, characterized in that: The method comprises the following components: carboxylated cellulose nanofiber solution, polyanionic cellulose solution and carboxymethyl chitosan solution; The volume ratio of the carboxylated cellulose nanofiber solution, the polyanionic cellulose solution, and the carboxymethyl chitosan solution is 1:1:

1.

2. The composite filling and reinforcing agent for excavated wood in semi-arid environments according to claim 1, characterized in that: The carboxylated cellulose nanofiber solution is an aqueous solution of carboxylated cellulose nanofibers; the polyanionic cellulose solution is an aqueous solution of polyanionic cellulose; and the carboxymethyl chitosan solution is an aqueous solution of carboxymethyl chitosan.

3. The composite filling and reinforcing agent for excavated wood in semi-arid environments according to claim 2, characterized in that: The concentrations of the carboxylated cellulose nanofiber solution, the polyanionic cellulose solution and the carboxymethyl chitosan solution are independently 1-5%.

4. The composite filling and reinforcing agent for excavated wood in semi-arid environments according to claim 2 or 3, characterized in that: The carboxylated cellulose nanofibers in the carboxylated cellulose nanofiber solution have a diameter of 4 to 10 nm and a length of 200 nm.

5. The method for preparing the composite filling and reinforcing agent for wooden articles excavated in semi-arid environments according to any one of claims 1 to 4, characterized in that: The following steps are involved: Carboxylated cellulose nanofibers, polyanionic cellulose and carboxymethyl chitosan are added to water and dissolved respectively to obtain carboxylated cellulose nanofiber solution, polyanionic cellulose solution and carboxymethyl chitosan solution respectively. The three solutions are then mixed in equal volumes and a solvent is added to obtain a composite filling and reinforcement agent for wooden objects unearthed in semi-arid environments.

6. The preparation method according to claim 5, characterized in that The solvents include water and isopropyl alcohol.

7. The preparation method according to claim 5, characterized in that The solvent and the carboxylated cellulose nanofiber solution are equal in volume.

8. Use of the composite filling and reinforcing agent for wooden articles unearthed in semi-arid environments according to any one of claims 1 to 4 in reinforcing decayed wood.

9. A method for reinforcing decayed wood cultural relics, characterized in that: The following steps are involved: The composite filling and reinforcing agent for wooden artifacts unearthed in a semi-arid environment according to any one of claims 1 to 4 is sprayed on the surface of rotten wooden artifacts for reinforcement.

10. The method for reinforcing decayed wood cultural relics according to claim 9, characterized in that: The number of reinforcements is ≥1.

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