Carbon quantum dots optimized furfuryl alcohol modified material and preparation method thereof

Abstract

The present application belongs to the technical field of wood modification, and particularly relates to a carbon quantum dot optimized furfuryl alcohol modified material and a preparation method thereof. The preparation method comprises the following steps: treating wood by a vacuum pressurized impregnation method with a carbon quantum dot / furfuryl alcohol modification liquid, then wrapping the wood with a high-temperature resistant waterproof material, and aging at room temperature. Finally, the wood is heated and solidified to obtain the carbon quantum dot optimized furfuryl alcohol modified material. The carbon quantum dot / furfuryl alcohol modification liquid of the present application realizes one agent with multiple effects, because the carbon quantum dots not only act as catalysts to catalyze the solidification of furfuryl alcohol in wood, but also act as wood modifiers to endow wood with excellent corrosion resistance. The carbon quantum dot optimized furfuryl alcohol modified material of the present application solves the problem of decreased toughness of furfuryl alcohol modified material, realizes the overall balance and optimization of the size stability, strength, toughness and biological degradation resistance of wood, and solves the problem of blackening of the color of the modified material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wood modification, and particularly relates to a carbon quantum dot optimized furfuryl alcohol modified material and a preparation method thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing the understanding of the background of the application without admitting that such information constitutes prior art.

[0003] Wood, as a renewable and recyclable green ecological material, is widely used in various fields such as construction, furniture and decoration due to its excellent physical and mechanical properties and unique environmental characteristics, such as high strength-to-weight ratio, easy processing and beautiful texture. However, there are a large number of hygroscopic groups in the main components of wood, which leads to dimensional instability, deformation and cracking, and causes microbial degradation such as mold and decay. Therefore, in order to avoid these problems, wood needs to be modified.

[0004] Furfuryl alcohol modification of wood is to impregnate wood cell cavities and cell walls with furfuryl alcohol as a modifier and a catalyst, and then solidify furfuryl alcohol resin in wood after heating, so as to improve the performance of wood. The furfuryl alcohol modification process is simple, and the dimensional stability, compression strength along the grain and biological degradation resistance of the modified material are significantly improved. In addition, the modifier is made from agricultural residues, which is widely available, low-toxic and environmentally friendly. Therefore, it has attracted much attention in the industry and has realized commercial production in some European countries and the United States. However, due to the brittleness of furfuryl alcohol resin itself and the use of acidic catalysts and heating conditions during the modification process, the toughness of the modified material is greatly reduced. When the weight gain rate of furfuryl alcohol modified material reaches 70%, the impact toughness of wood can be reduced by 57%. At present, the methods of removing lignin in wood and introducing flexible polymers can alleviate the toughness reduction of furfuryl alcohol modified material to some extent, but the effect is not ideal, and the process is complex and difficult to industrialize. So far, there has been no research to design catalysts to improve the toughness of furfuryl alcohol modified material. In addition, traditional catalysts such as sulfuric acid and maleic anhydride have a violent reaction and single function, which restricts the popularization and application of furfuryl alcohol modification technology in the wood modification industry. Therefore, it is of great practical value to design a mild and multi-effect catalyst to optimize the furfuryl alcohol modification technology of wood.

[0005] Carbon quantum dots (CQDs) are a kind of zero-dimensional carbon nanomaterials, mainly composed of C, H and O elements. It has the advantages of small particle size and large specific surface area, and the surface has many groups, which can provide rich center active sites for catalysis; It has excellent electron transfer ability and can be used as electron acceptor and electron donor. In addition, CQDs have good hydrophilicity, low toxicity and widely synthesized materials, and the synthesis method is simple, so it becomes an ideal catalyst. Therefore, in this study, carbon quantum dots are used to catalyze furfuryl alcohol monomer curing, which can significantly improve the dimensional stability, compressive strength and biological degradation resistance of wood, improve the toughness reduction problem, realize the overall balance and optimization of dimensional stability, strength, toughness and biological degradation resistance, and solve the problem of blackening of material color. SUMMARY

[0006] The purpose of the present application is to solve the problem of toughness reduction of furfuryl alcohol modified material, to realize the overall balance and optimization of wood dimensional stability, strength, toughness and biological degradation resistance by designing a new catalyst, and to solve the problem of blackening of material color, and to provide a kind of carbon quantum dots optimized furfuryl alcohol modified material and its preparation method.

[0007] In order to achieve the above purpose, the following technical solutions are adopted in this application:

[0008] In the first aspect, the application provides a preparation method of carbon quantum dots optimized furfuryl alcohol modified material. The carbon quantum dots / furfuryl alcohol modified liquid is treated on wood by vacuum pressure impregnation method, then the wood is wrapped with high-temperature resistant waterproof material, and placed at room temperature for aging, so that the modifier can enter the cell wall of the wood better. Then, the wood is heated and cured in a drying oven or drying kiln, so as to obtain the carbon quantum dots optimized furfuryl alcohol modified material.

[0009] Further, the carbon quantum dots are surface ion modified carbon quantum dots.

[0010] Further, the method for obtaining the carbon quantum dots / furfuryl alcohol modified liquid comprises:

[0011] The carbon quantum dots, furfuryl alcohol and water are mixed to obtain the carbon quantum dots / furfuryl alcohol modified liquid.

[0012] Further, the concentration of the carbon quantum dots is 0.5-5% by mass percentage, the concentration of furfuryl alcohol is 10-70%, and the water is 25-89.5%.

[0013] The vacuum pressure impregnation method is first vacuum treated for 30-120 min under the condition of vacuum degree-0.05-0.1 MPa, then the carbon quantum dots / furfuryl alcohol modified liquid is introduced, and then pressure treated for 60-180 min under the condition of pressure 0-2 MPa.

[0014] Further, the high-temperature resistant waterproof material is tin foil and / or silicon oil paper, and the room temperature aging time is 12-72h.

[0015] The heating and curing treatment is first at 60-80 DEG C for 1-5h, and then at 100-120 DEG C for 5-24h.

[0016] In the second aspect, the application provides a wood prepared by the preparation method of the furfuryl alcohol modified material optimized by the carbon quantum dots.

[0017] The application has the following advantages:

[0018] The carbon quantum dots / furfuryl alcohol modified liquid of the application can catalyze the curing of furfuryl alcohol in wood as a catalyst, and can also endow wood with excellent corrosion resistance as a wood modifier, thus realizing multiple effects with one agent.

[0019] The carbon quantum dots / furfuryl alcohol modified material of the application solves the problem of decreased toughness of furfuryl alcohol modified material, realizes the overall balance and optimization of size stability, strength, toughness and biological degradation resistance of wood, and solves the problem of blackening of the modified material.

[0020] The preparation method of the carbon quantum dots of the application is simple, has no solid by-product, is time-saving and low in cost, and can be widely applied on a large scale. The carbon quantum dots of the application are ion-modified, and contain rich hydroxyl groups, carboxyl groups and ions on the surface, which can play the roles of acid catalysis and hydrogen bond catalysis, and have good catalytic furfuryl alcohol monomer curing and bacteriostatic properties. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of the color of the modified materials of Comparative Examples 1 and 3 and Example 2.

[0022] Figure 2 is a schematic diagram of the bending strength and elastic modulus of Comparative Examples 1 and 2 and Example 1.

[0023] Figure 3 is a schematic diagram of the compression strength along the grain of Comparative Examples 1 and 2 and Example 1.

[0024] Figure 4 is a schematic diagram of the impact toughness of Comparative Examples 1, 3 and Example 2.

[0025] Figure 5 is a schematic diagram of the corrosion resistance of Comparative Examples 1, 3 and Example 2.

[0026] Figure 6 is a schematic diagram of the size stability of Comparative Example 3 and Example 2. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The embodiments provide detailed implementation methods and specific operation processes, but the scope of protection of the present invention is not limited to the following embodiments.

[0028] In the following examples, the carbon quantum dot modified liquid is prepared using existing methods, such as the "ion-based carbon quantum dots and their application in resin curing" proposed in Chinese patent application CN118956387A. Using polybasic organic acids and fluoroborates as raw materials, the mixture is fully dissolved by ultrasound and then heated in a microwave oven for 3–10 minutes to obtain surface-ion-modified carbon quantum dots. Then, the carbon quantum dots, furfuryl alcohol, and water are mixed in a certain proportion to obtain a carbon quantum dot / furfuryl alcohol modified liquid.

[0029] Example 1

[0030] Preparation of carbon quantum dot / furfuryl alcohol modified solution: Using 4 parts oxalic acid and 1 part sodium fluoroborate as raw materials, the solutions were fully dissolved by ultrasonication and then heated in a microwave oven for 5 minutes to obtain surface ion-modified carbon quantum dots. A carbon quantum dot / furfuryl alcohol modified solution was prepared by stirring with a glass rod according to the following mass percentages: carbon quantum dot concentration 1.25%, furfuryl alcohol concentration 15%, yielding a homogeneous, clear yellow solution.

[0031] Wood processing and characterization: Poplar was selected and the wood was processed into test materials with dimensions of 20mm (axial) × 20mm (tangential) × 20mm (radial), 80mm (axial) × 10mm (tangential) × 4mm (radial), and 30mm (axial) × 20mm (tangential) × 20mm (radial).

[0032] Vacuum pressure impregnation of wood: Vacuum treatment was performed for 45 minutes under a vacuum of -0.05 MPa, followed by introduction of carbon quantum dot / furfuryl alcohol modified solution, and then pressure treatment was performed for 90 minutes under a pressure of 0.5 MPa. After impregnation, excess modifier was wiped off the surface, and the wood was wrapped in aluminum foil and aged at room temperature for 48 hours to allow the modifier to better penetrate into the wood cell walls. Then, the wood was placed in a drying oven for heat curing, first treated at 80℃ for 2 hours, and then treated at 105℃ for 10 hours. The aluminum foil was removed, and finally dried at 80℃ to constant weight to obtain carbon quantum dot-optimized furfuryl alcohol modified wood.

[0033] Example 2

[0034] Preparation of carbon quantum dot / furfuryl alcohol modified solution: Using 3 parts citric acid and 2 parts sodium fluoroborate as raw materials, the solutions were fully dissolved by ultrasonication and then heated in a microwave oven for 8 minutes to obtain surface ion-modified carbon quantum dots. A carbon quantum dot / furfuryl alcohol modified solution was prepared by stirring with a glass rod according to the following mass percentages: carbon quantum dot concentration 2.5%, furfuryl alcohol concentration 30%, yielding a homogeneous, clear yellow solution.

[0035] Wood processing and characterization: Radiata pine was selected and the wood was processed into test materials with dimensions of 20mm (axial) × 20mm (tangential) × 20mm (radial), 80mm (axial) × 10mm (tangential) × 4mm (radial), and 30mm (axial) × 20mm (tangential) × 20mm (radial).

[0036] Vacuum pressure impregnation of wood: Vacuum treatment was performed for 60 minutes under a vacuum of -0.1 MPa, followed by introduction of a carbon quantum dot / furfuryl alcohol modified solution, and then pressure treatment was carried out for 120 minutes at 0.8 MPa. After impregnation, excess modifier was wiped off the surface, and the wood was wrapped in aluminum foil and aged at room temperature for 36 hours to allow the modifier to better penetrate the wood cell walls. Then, the wood was placed in a drying oven for heat curing, first treated at 60℃ for 2 hours, and then at 110℃ for 10 hours. The aluminum foil was removed, and finally, the wood was dried at 60℃ to constant weight, thus obtaining carbon quantum dot-optimized furfuryl alcohol modified wood.

[0037] Example 3

[0038] Preparation of carbon quantum dot / furfuryl alcohol modified solution: Using 5 parts citric acid and 2 parts ammonium fluoroborate as raw materials, the solutions were fully dissolved by ultrasonication and then heated in a microwave oven for 12 minutes to obtain surface ion-modified carbon quantum dots. A carbon quantum dot / furfuryl alcohol modified solution was prepared by stirring with a glass rod according to the following mass percentages: carbon quantum dot concentration 0.5%, furfuryl alcohol concentration 10%, yielding a homogeneous, clear yellow solution.

[0039] Wood processing and characterization: Selected Pinus sylvestris, the wood was processed into test materials with dimensions of 20mm (axial) × 20mm (tangential) × 20mm (radial), 80mm (axial) × 10mm (tangential) × 4mm (radial), and 30mm (axial) × 20mm (tangential) × 20mm (radial);

[0040] Vacuum pressure impregnation of wood: Vacuum treatment was performed for 30 minutes under a vacuum of -0.08 MPa, followed by the introduction of carbon quantum dot / furfuryl alcohol modified solution, and then pressure treatment was carried out for 60 minutes under a pressure of 0.3 MPa. After impregnation, excess modifier was wiped off the surface, and the wood was wrapped with silicone paper and aged at room temperature for 72 hours to allow the modifier to better penetrate into the wood cell walls. Then, the wood was placed in a drying oven for heat curing, first treated at 60℃ for 2 hours, and then at 120℃ for 15 hours. The silicone paper was removed, and finally, the wood was dried at 40℃ to constant weight, thus obtaining carbon quantum dot-optimized furfuryl alcohol modified wood.

[0041] Example 4

[0042] Preparation of carbon quantum dot / furfuryl alcohol modified solution: Using 2 parts oxalic acid and 1 part ammonium fluoroborate as raw materials, the solutions were fully dissolved by ultrasonication and then heated in a microwave oven for 8 minutes to obtain surface ion-modified carbon quantum dots. A carbon quantum dot / furfuryl alcohol modified solution was prepared by stirring with a glass rod according to the following mass percentages: carbon quantum dot concentration 5%, furfuryl alcohol concentration 70%, yielding a homogeneous, clear yellow solution.

[0043] Wood processing and characterization: Eucalyptus wood was selected and processed into test materials with dimensions of 20mm (axial) × 20mm (tangential) × 20mm (radial), 80mm (axial) × 10mm (tangential) × 4mm (radial), and 30mm (axial) × 20mm (tangential) × 20mm (radial).

[0044] Vacuum pressure impregnation of wood: Vacuum treatment was performed for 120 min at a vacuum of -0.1 MPa, followed by introduction of carbon quantum dot / furfuryl alcohol modified solution, and then pressure treatment was carried out for 180 min at 1.5 MPa. After impregnation, excess modifier was wiped off the surface, and the wood was wrapped in aluminum foil and aged at room temperature for 72 h to allow the modifier to better penetrate the wood cell walls. Then, the wood was placed in a drying oven for heat curing, first treated at 80℃ for 5 h, and then at 110℃ for 20 h. The aluminum foil was removed, and finally dried at 50℃ to constant weight, thus obtaining carbon quantum dot-optimized furfuryl alcohol modified wood.

[0045] Example 5

[0046] Preparation of carbon quantum dot / furfuryl alcohol modified solution: Using 2 parts oxalic acid and 1 part ammonium fluoroborate as raw materials, the solutions were fully dissolved by ultrasonication and then heated in a microwave oven for 10 minutes to obtain surface ion-modified carbon quantum dots. A carbon quantum dot / furfuryl alcohol modified solution was prepared by stirring with a glass rod according to the following mass percentages: carbon quantum dot concentration 3%, furfuryl alcohol concentration 50%, yielding a homogeneous, clear yellow solution.

[0047] Wood processing and characterization: Poplar was selected and the wood was processed into test materials with dimensions of 20mm (axial) × 20mm (tangential) × 20mm (radial), 80mm (axial) × 10mm (tangential) × 4mm (radial), and 30mm (axial) × 20mm (tangential) × 20mm (radial).

[0048] Vacuum pressure impregnation of wood: Vacuum treatment was performed for 100 min at a vacuum of -0.08 MPa, followed by introduction of carbon quantum dot / furfuryl alcohol modified solution, and then pressure treatment was carried out for 160 min at 1.2 MPa. After impregnation, excess modifier was wiped off the surface, and the wood was wrapped with silicone paper and aged at room temperature for 60 h to allow the modifier to better penetrate the wood cell walls. Then, the wood was placed in a drying oven for heat curing, first treated at 70℃ for 4 h, and then at 120℃ for 15 h. The silicone paper was removed, and finally, the wood was dried at 70℃ to constant weight, thus obtaining carbon quantum dot-optimized furfuryl alcohol modified wood.

[0049] Example 6

[0050] Preparation of carbon quantum dot / furfuryl alcohol modified solution: Using 4 parts oxalic acid and 1 part ammonium fluoroborate as raw materials, the solutions were fully dissolved by ultrasonication and then heated in a microwave oven for 10 minutes to obtain surface ion-modified carbon quantum dots. A carbon quantum dot / furfuryl alcohol modified solution was prepared by stirring with a glass rod according to the following mass percentages: carbon quantum dot concentration 1.5%, furfuryl alcohol concentration 20%, yielding a homogeneous, clear yellow solution.

[0051] Wood processing and characterization: Radiata pine was selected and the wood was processed into test materials with dimensions of 20mm (axial) × 20mm (tangential) × 20mm (radial), 80mm (axial) × 10mm (tangential) × 4mm (radial), and 30mm (axial) × 20mm (tangential) × 20mm (radial).

[0052] Vacuum pressure impregnation of wood: Vacuum treatment was performed for 30 minutes under a vacuum of -0.1 MPa, followed by introduction of carbon quantum dot / furfuryl alcohol modified solution, and then pressure treatment was carried out for 60 minutes under a pressure of 1.5 MPa. After impregnation, excess modifier was wiped off the surface, and the wood was wrapped with silicone paper and aged at room temperature for 12 hours to allow the modifier to better penetrate into the wood cell walls. Then, the wood was placed in a drying oven for heat curing, first treated at 80℃ for 4 hours, and then at 100℃ for 9 hours. The silicone paper was removed, and finally, the wood was dried at 50℃ to constant weight, thus obtaining carbon quantum dot-optimized furfuryl alcohol modified wood.

[0053] It should be noted that for the processing and characterization of wood, bark-free wood can be selected. If it is a heartwood species, sapwood should be selected as much as possible, and the wood should be sawn into specimens of a certain size. Broadleaf woods such as poplar, oak, and eucalyptus can be selected, as well as coniferous woods such as cedar, radiata pine, and larch.

[0054] In the above embodiments, during vacuum pressure impregnation of wood, the carbon quantum dot / furfuryl alcohol modified solution can be treated with the wood using a vacuum pressure impregnation method. After impregnation, excess modifier on the surface is wiped off with a paper towel. The wood is then aged at room temperature to allow the modifier to better penetrate the wood cell walls. Finally, the wood is placed in a drying oven for heat curing treatment, thereby obtaining carbon quantum dot-optimized furfuryl alcohol modified wood. The physical and mechanical properties of the modified wood, including impact toughness, flexural strength and modulus of elasticity, compressive strength, dimensional stability, and corrosion resistance, are all improved.

[0055] Comparative Example 1

[0056] Untreated wood was dried to constant weight at 103°C to prepare physical and mechanical test specimens of the above dimensions.

[0057] Comparative Example 2

[0058] By mass percentage, the concentration of maleic anhydride was 1.25% and the concentration of furfuryl alcohol was 15%, resulting in a homogeneous, pale yellow, clear solution; then, the wood was impregnated under vacuum pressure as in Example 1.

[0059] Comparative Example 3

[0060] By mass percentage, the concentration of maleic anhydride was 2.5% and the concentration of furfuryl alcohol was 30%, resulting in a homogeneous, pale yellow, clear solution; then, the wood was impregnated under vacuum pressure as in Example 2.

[0061] After modification treatment, the weight gain, volume increase, and density change rates of Examples 1 and 2 and Comparative Examples 2 and 3 are shown in Table 1. As can be seen from the table, the weight gain and volume increase rates of Example 2, using carbon quantum dots as a catalyst, are both greater than those of Comparative Example 3, which uses a traditional catalyst. The density change rate indicates that the density changes of both are basically the same. Similarly, Examples 1 and Comparative Example 2 also show similar changes. This indicates that the carbon quantum dot catalyst can successfully solidify furfuryl alcohol inside the wood and exert a strong swelling effect on the cell wall.

[0062] Table 1 shows the weight gain rate, volume increase rate, and density change rate for Examples 1 and 2 and Comparative Examples 2 and 3.

[0063]

[0064] Figure 1 These are schematic diagrams illustrating the material colors of Comparative Examples 1, 3, and Example 2. Figure 1As can be seen, Comparative Example 2 is black, which is a darker color, while Example 2, which uses carbon quantum dots as a catalyst, is brown, thus improving the problem of the furfuryl alcohol modified material turning black.

[0065] Figure 2 This is a schematic diagram showing the flexural strength and modulus of elasticity of Comparative Examples 1 and 2 and Example 1. Figure 2 As can be seen from the data, the flexural strength and elastic modulus of Example 1, which uses carbon quantum dots as a catalyst, are both greater than those of Comparative Example 2.

[0066] Figure 3 This is a schematic diagram of the parallel-grain compressive strength of Comparative Examples 1 and 2 and Example 1. Figure 3 As can be seen from the data, the parallel compressive strength of Example 1, which uses carbon quantum dots as a catalyst, is greater than that of Comparative Example 2.

[0067] Figure 4 This is a schematic diagram of the impact toughness of Comparative Examples 1, 3, and Example 2. Figure 4 As can be seen, the toughness of Comparative Example 3 decreased by 35%, while Example 2, which used carbon quantum dots as a catalyst, improved by 38% compared to Comparative Example 3, and even exceeded the toughness of the untreated material. This is mainly due to the interaction between carbon quantum dots and wood.

[0068] Figure 5 This is a schematic diagram illustrating the corrosion resistance of Comparative Examples 1, 3, and Example 2. Figure 5 As can be seen, Comparative Example 3 has a certain degree of corrosion resistance, while Example 2, which uses carbon quantum dots as a catalyst, has excellent corrosion resistance and achieves a bactericidal effect.

[0069] Figure 6 This is a schematic diagram illustrating the dimensional stability of Comparative Example 3 and Example 2. Figure 6 As can be seen from the data, compared with Comparative Example 2, the anti-swelling rate of Example 2, which uses carbon quantum dots as a catalyst, increased by 22% and reached 80%, indicating that the carbon quantum dot-optimized furfuryl alcohol modified material has good dimensional stability.

Claims

1. A method for preparing carbon quantum dot-optimized furfuryl alcohol-modified materials, used to solve the problem of blackening of furfuryl alcohol-modified materials, characterized in that, Wood was treated with carbon quantum dot / furfuryl alcohol modified liquid by vacuum pressure impregnation, then the wood was wrapped with a high-temperature resistant and waterproof material and aged at room temperature; finally, the wood was placed in a drying oven or drying kiln for heating and curing, thereby obtaining carbon quantum dot optimized furfuryl alcohol modified material. The carbon quantum dots are surface-ion-modified carbon quantum dots, prepared by using polybasic organic acids and fluoroborates as raw materials, fully dissolving them by ultrasound, and then heating them in a microwave oven for 3-10 minutes. The carbon quantum dot / furfuryl alcohol modified solution is obtained by mixing carbon quantum dots, furfuryl alcohol, and water in a certain proportion, wherein the carbon quantum dot / furfuryl alcohol modified solution has the following mass percentages: carbon quantum dot concentration of 0.5-5%, furfuryl alcohol concentration of 10-70%, and water concentration of 25-89.5%. The aging time at room temperature is 12-72 hours. The heating and curing procedure is to first treat at 60-80℃ for 1-5 hours, then treat at 100-120℃ for 5-24 hours, and finally remove the high-temperature resistant waterproof material and dry at 40-80℃ to constant weight.

2. The preparation method according to claim 1, characterized in that, The vacuum pressure impregnation process involves first vacuum treatment for 30 to 120 minutes under a vacuum of -0.05 to -0.1 MPa, then introducing the carbon quantum dot / furfuryl alcohol modified solution, and finally pressurizing the solution for 60 to 180 minutes under a pressure of 0 to 2 MPa.

3. The preparation method according to claim 1, characterized in that, The high-temperature resistant and waterproof material is tin foil and / or silicone paper.

4. A type of wood prepared by the preparation method according to any one of claims 1-3.

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