Preparation method of ultra-flexible wood with three-dimensional network structure

Abstract

A method for preparing ultra-flexible wood with a three-dimensional network structure relates to a method for constructing a three-dimensional network structure within the pores of wood. This invention addresses the existing difficulties in constructing new three-dimensional structures within the pores of wood, as well as the problem that cross-sections of wood are prone to breaking and difficult to bend. The methods include: 1. Impregnation displacement; 2. Water infiltration. This invention is used to prepare ultra-flexible wood with a three-dimensional network structure.

Description

Technical Field

[0001] The invention relates to a method for constructing a three-dimensional network structure in wood pores. Background Art

[0002] Wood is a complex biopolymer composite material with a multi-scale structure. In terms of physical structure, wood has a natural anisotropic hierarchical structure composed of fiber cells and tracheids arranged in a direction, forming a honeycomb network structure with different pore sizes in the wood. In terms of chemical composition, the main components of wood are cellulose, hemicellulose and lignin. Nano-scale cellulose can be extracted from wood through mechanical, chemical, biological and other processes to achieve efficient utilization of wood. The hydroxyl groups on the cellulose macromolecular chain form a large number of hydrogen bonds within and between cellulose molecules, giving cellulose a stable structure, making cellulose difficult to dissolve in common solvents. Among them, solvent systems such as N-methylmorpholine-N-oxide (NMMNO) and lithium chloride / dimethylacetamide (DMAc) can achieve the dissolution of cellulose, but existing technologies have difficulty in constructing new three-dimensional structures in the pores of wood, and the cross-section of wood is easy to break and difficult to bend. Summary of the Invention

[0003] The present invention aims to solve the existing problems of difficulty in constructing new three-dimensional structures in the pores of wood and the fact that the cross-section of wood is easy to break and difficult to bend, and further provides a method for preparing ultra-flexible wood with a three-dimensional network structure.

[0004] A method for preparing ultra-flexible wood with a three-dimensional network structure is carried out according to the following steps:

[0005] 1. Impregnation replacement:

[0006] Delignified wood is placed in a zinc chloride solution for reaction, and then the reacted wood is placed in ethanol and deionized water in turn for static, then taken out and placed in a tert-butanol aqueous solution to replace the original water in the pores, and finally the wood is sequentially frozen and freeze-dried to obtain wood with a three-dimensional network structure;

[0007] 2. Water infiltration:

[0008] The wood with a three-dimensional network structure is immersed in water to obtain an ultra-flexible wood with a three-dimensional network structure.

[0009] The beneficial effects of the present invention are:

[0010] 1. After cellulose is dissolved and regenerated in zinc chloride solution, a three-dimensional network structure is constructed in the pore structure;

[0011] 2. A three-dimensional network structure is constructed within the pore structure of wood, enriching the pore structure of wood. This is expected to be further applied in production fields such as electrocatalysis, flexible sensors, wood-based evaporators, and wood-based nanogenerators.

[0012] 3. After being soaked in water for a period of time, the wood treated with zinc chloride has good flexibility and can be completely folded in half on the cross section.

[0013] 4. Using zinc chloride to treat wood is low-cost, simple, and can be produced on a large scale;

[0014] 5. The reagents such as zinc chloride used in the present invention are all common raw materials, have low requirements on reaction equipment, and the reaction conditions are mild.

[0015] Figures in the specification

[0016] Figure 1 This is an SEM image of the cross section of the delignified wood described in step 1 of Example 1.

[0017] Figure 2 This is an SEM image of the wood with a three-dimensional network structure prepared in step 1 of Example 1;

[0018] Figure 3 This is a schematic diagram of the ultra-flexible wood with a three-dimensional network structure prepared in Example 1 being folded in half at room temperature;

[0019] Figure 4 Schematic diagram of stress-strain curves of tensile tests of the delignified wood described in step 1 of Example 1 and the wood with a three-dimensional network structure prepared in step 1 of Example 1;

[0020] Figure 5 Schematic diagram of stress-strain curves of bending tests of the delignified wood described in step 1 of Example 1 and the wood with a three-dimensional network structure prepared in step 1 of Example 1;

[0021] Figure 6 This is a bar graph of the tensile strength and bending strength of the delignified wood described in step 1 of Example 1 and the wood with a three-dimensional network structure prepared in step 1 of Example 1. DETAILED DESCRIPTION

[0022] Specific embodiment 1: This embodiment is a method for preparing ultra-flexible wood with a three-dimensional network structure, which is carried out according to the following steps:

[0023] 1. Impregnation replacement:

[0024] Delignified wood is placed in a zinc chloride solution for reaction, and then the reacted wood is placed in ethanol and deionized water in turn for static, then taken out and placed in a tert-butanol aqueous solution to replace the original water in the pores, and finally the wood is sequentially frozen and freeze-dried to obtain wood with a three-dimensional network structure;

[0025] 2. Water infiltration:

[0026] The wood with a three-dimensional network structure is immersed in water to obtain an ultra-flexible wood with a three-dimensional network structure.

[0027] This specific embodiment fills the pores of the wood with zinc chloride solution, thereby causing the cellulose in the cell walls of the wood to partially dissolve and regenerate, and constructing a new three-dimensional network structure in the pores of the wood. Due to the hydrogen bond connection between the regenerated cellulose, the wood with a three-dimensional network structure has improved tensile and bending strength compared to wood that has not been treated with zinc chloride solution. It was also found that after the wood with a three-dimensional network structure was soaked in water for a period of time, the cross-section of the wood had super high flexibility. Therefore, this specific embodiment improves the natural configuration of the wood, while giving the wood excellent flexibility characteristics, and realizing efficient utilization of the wood. Zinc chloride has the advantages of being green, stable, cheap, and easy to recycle. In addition, during the dissolution of cellulose by zinc chloride aqueous solution, cellulose does not need to be activated, and the operation is simple and the conditions are mild.

[0028] The beneficial effects of this embodiment are:

[0029] 1. After cellulose is dissolved and regenerated in zinc chloride solution, a three-dimensional network structure is constructed in the pore structure;

[0030] 2. A three-dimensional network structure is constructed within the pore structure of wood, enriching the pore structure of wood. This is expected to be further applied in production fields such as electrocatalysis, flexible sensors, wood-based evaporators, and wood-based nanogenerators.

[0031] 3. After being soaked in water for a period of time, the wood treated with zinc chloride has good flexibility and can be completely folded in half on the cross section.

[0032] 4. Using zinc chloride to treat wood is low-cost, simple, and can be produced on a large scale;

[0033] 5. The reagents such as zinc chloride used in this embodiment are all common raw materials, which have low requirements on reaction equipment and mild reaction conditions.

[0034] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the delignified wood in step 1 is processed by placing the wood in a sodium chlorite solution at a temperature of 60°C to 80°C until the wood turns white, thereby obtaining delignified wood; the mass percentage of the sodium chlorite solution is 1% to 3%, and the pH is 4.5 to 5.0. Other aspects are the same as specific embodiment 1.

[0035] Specific embodiment 3: This embodiment differs from specific embodiment 1 or 2 in that the wood is balsa wood, poplar, basswood or Pinus sylvestris var. mongolica. Other aspects are the same as specific embodiment 1 or 2.

[0036] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the wood is a cross-section wood with a thickness of 1 mm to 5 mm. Other aspects are the same as specific embodiments 1 to 3.

[0037] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the mass percentage of zinc chloride in the zinc chloride solution in step 1 is 60% to 80%. Other aspects are the same as specific embodiments 1 to 4.

[0038] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that in step 1, the delignified wood is placed in a zinc chloride solution at a temperature of 50° C. to 80° C. for 1 to 6 hours. Other steps are the same as specific embodiments 1 to 5.

[0039] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that in step 1, the reacted wood is first placed in ethanol and allowed to stand for 10 to 60 minutes, and then placed in deionized water and allowed to stand for 1 to 6 hours. Other steps are the same as specific embodiments 1 to 6.

[0040] Specific embodiment 8: This embodiment differs from Specific embodiments 1 to 7 in that, in step 1, the pores are removed and then placed in a tert-butanol aqueous solution for 6 to 18 hours to displace the original water in the pores; the mass percentage of tert-butanol in the tert-butanol aqueous solution is 15% to 25%. Other aspects are the same as Specific embodiments 1 to 7.

[0041] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the freezing in step 1 is carried out at a temperature of -15°C to -30°C for 10 to 14 hours; and the freeze-drying in step 1 is carried out at a cold trap temperature of -65°C to -40°C and a vacuum of 1 Pa to 5 Pa for 3 to 8 hours. Other aspects are the same as specific embodiments 1 to 8.

[0042] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that in step 2, the wood with a three-dimensional network structure is immersed in water for 3 hours to 48 hours. Other aspects are the same as specific embodiments 1 to 9.

[0043] The following examples are used to verify the beneficial effects of the present invention:

[0044] Example 1:

[0045] A method for preparing ultra-flexible wood with a three-dimensional network structure is carried out according to the following steps:

[0046] 1. Impregnation replacement:

[0047] Delignified wood was placed in a zinc chloride solution at 60°C for 3 hours, then placed in ethanol for 30 minutes, then placed in deionized water for 4 hours, then taken out and placed in a tert-butanol aqueous solution for 8 hours to replace the original water in the pores. Finally, the wood was frozen at -25°C for 10 hours, and then freeze-dried in a cold trap at -65°C and a vacuum of 5 Pa for 6 hours to obtain wood with a three-dimensional network structure.

[0048] The mass percentage of zinc chloride in the zinc chloride solution is 70%; the mass percentage of tert-butanol in the tert-butanol aqueous solution is 20%;

[0049] 2. Water infiltration:

[0050] The wood with a three-dimensional network structure is placed in water and immersed for 12 hours to obtain an ultra-flexible wood with a three-dimensional network structure.

[0051] The delignified wood in step 1 is specifically carried out according to the following steps: placing the wood in a sodium chlorite solution and treating it at a temperature of 70°C for 16 hours until the wood turns white to obtain delignified wood; the mass percentage of the sodium chlorite solution is 2%, and the pH is 4.6.

[0052] The wood is balsa wood.

[0053] The wood is cross-section wood, and the length, width and thickness of the wood are 30 mm, 30 mm and 2 mm respectively.

[0054] Figure 1 This is an SEM image of the cross section of the delignified wood described in step 1 of Example 1.

[0055] Figure 2 This is an SEM image of the wood with a three-dimensional network structure prepared in step 1 of Example 1; Figure 1 Comparison shows that new network structures are constructed in pores of different sizes in wood.

[0056] The delignified wood described in step 1 of Example 1 and the wood with a three-dimensional network structure prepared in step 1 are easily broken when folded in half at room temperature; the delignified wood described in step 1 of Example 1 is immersed in water for 12 hours, but cannot be folded in half even after hydration and is easily broken.

[0057] Figure 3 This is a schematic diagram of the ultra-flexible wood with a three-dimensional network structure prepared in Example 1 being folded in half at room temperature. As can be seen from the figure, the cross-section of the treated wood has good flexibility and can be completely folded in half.

[0058] The tensile performance test was carried out according to the GB / T 528-2009 test standard at normal pressure and room temperature and a test speed of 2 mm / min. The bending performance test was carried out according to the GB / T 1936-1-2009 test standard at normal pressure and room temperature and a test speed of 2 mm / min.

[0059] Figure 4 Schematic diagram of stress-strain curves of tensile tests of the delignified wood described in step 1 of Example 1 and the wood with a three-dimensional network structure prepared in step 1 of Example 1; Figure 5 Schematic diagram of stress-strain curves of bending tests of the delignified wood described in step 1 of Example 1 and the wood with a three-dimensional network structure prepared in step 1 of Example 1; Figure 6 This is a bar graph of the tensile strength and bending strength of the delignified wood described in step 1 of Example 1 and the wood with a three-dimensional network structure prepared in step 1 of Example 1. Experiments show that the tensile strength of the delignified wood is 1.75 MPa, and the bending strength is 1.09 MPa; the tensile strength of the wood with a three-dimensional network structure prepared in step 1 is 1.95 MPa, and the bending strength is 1.32 MPa. It can be seen that the three-dimensional network structure in the wood pores enhances the tensile and bending strength of the delignified wood.

Claims

1. A method for preparing ultra-flexible wood with a three-dimensional network structure, characterized in that It is carried out in the following steps:

1. Impregnation replacement: Delignified wood is placed in a zinc chloride solution at a temperature of 50°C to 80°C for 1 to 6 hours. The reacted wood is then placed in ethanol and deionized water in turn for a static state. The wood is then taken out and placed in a tert-butanol aqueous solution to displace the original water in the pores. Finally, the wood is sequentially frozen and freeze-dried to obtain wood with a three-dimensional network structure. The mass percentage of zinc chloride in the zinc chloride solution is 60% to 80%; 2. Water infiltration: The wood with a three-dimensional network structure is placed in water and immersed for 3 hours to 48 hours to obtain an ultra-flexible wood with a three-dimensional network structure.

2. The method for preparing a super-flexible wood with a three-dimensional network structure according to claim 1, characterized in that The delignified wood in step 1 is specifically processed according to the following steps: placing the wood in a sodium chlorite solution and treating it at a temperature of 60°C to 80°C until the wood turns white to obtain delignified wood; the mass percentage of the sodium chlorite solution is 1% to 3%, and the pH is 4.5 to 5.

0.

3. The method for preparing a super-flexible wood with a three-dimensional network structure according to claim 2, characterized in that The wood is poplar, basswood or Pinus sylvestris var. mongolica.

4. The method for preparing a super-flexible wood with a three-dimensional network structure according to claim 2, characterized in that The wood is cross-section wood, and the thickness of the wood is 1mm to 5mm.

5. The method for preparing a super-flexible wood with a three-dimensional network structure according to claim 1, characterized in that In step 1, the reacted wood is first placed in ethanol and allowed to stand for 10 minutes to 60 minutes, and then placed in deionized water and allowed to stand for 1 hour to 6 hours.

6. The method for preparing a super-flexible wood with a three-dimensional network structure according to claim 1, characterized in that The sample is taken out in step 1 and placed in a tert-butanol aqueous solution for 6 to 18 hours to replace the original water in the pores; the mass percentage of tert-butanol in the tert-butanol aqueous solution is 15% to 25%.

7. The method for preparing ultra-flexible wood with a three-dimensional network structure according to claim 1, characterized in that The freezing in step 1 is specifically performed at a temperature of -15°C to -30°C for 10 to 14 hours; the freeze-drying in step 1 is specifically performed at a cold trap temperature of -65°C to -40°C and a vacuum degree of 1 Pa to 5 Pa for 3 to 8 hours.

Images