A hydrothermally treated modified bamboo shaving, a preparation method thereof and a bamboo cement shaving board

Abstract

This invention provides a hydrothermal modified bamboo shavings, its preparation method, and a bamboo-based cement particleboard, belonging to the field of cement particleboard. The preparation method of the hydrothermal modified bamboo shavings provided by this invention includes: mixing pretreated bamboo shavings with water, subjecting them to hydrothermal treatment, and then drying them to obtain hydrothermal modified bamboo shavings; the hydrothermal treatment temperature is 70~110℃; the hydrothermal treatment time is 110~130 min. The water-soluble sugar content in the hydrothermal modified bamboo shavings prepared by the method provided by this invention is reduced by 60.1~66.7% compared to unmodified bamboo shavings, the formic acid content is 0, and the acetic acid content is reduced by 82.5~94.5% compared to unmodified bamboo shavings; the bamboo-based cement particleboard prepared using the hydrothermal modified bamboo shavings exhibits good mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of cement particleboard, and more particularly to a hydrothermal modified bamboo shavings, its preparation method, and a bamboo cement particleboard. Background Technology

[0002] Bamboo cement particleboard is an inorganic engineered wood product made with silicate cement as the binder and bamboo shavings as reinforcement and toughening materials. It possesses excellent properties such as high strength, water resistance, and flame retardancy, and is widely used in building wall materials, outdoor furniture materials, and other fields. The mechanical properties of bamboo cement particleboard are closely related to the strength of the bamboo shavings themselves, the degree of hydration reaction of the silicate cement, and the interface between the bamboo shavings and the hydration products.

[0003] The poor compatibility between bamboo and silicate cement is due to the higher content of water-soluble sugars and carboxylic acids in bamboo, which have an "anti-setting" effect on silicate cement. These "anti-setting" components directly affect the degree of hydration reaction of silicate cement, the types of hydration products, and the interface between the hydration products and bamboo shavings. Therefore, effectively reducing the content of "anti-setting" components in bamboo to prepare bamboo silicate cement particleboard with good mechanical properties has become an urgent technical problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide hydrothermal modified bamboo shavings, a method for preparing the same, and a bamboo-based cement particleboard. The hydrothermal modified bamboo shavings prepared by the method provided by this invention have low contents of water-soluble sugars and organic carboxylic acids, and the bamboo-based cement particleboard prepared using these hydrothermal modified bamboo shavings exhibits good mechanical properties.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing hydrothermally modified bamboo shavings, comprising: mixing pretreated bamboo shavings with water, subjecting the mixture to hydrothermal treatment, and then drying the mixture to obtain hydrothermally modified bamboo shavings. The temperature of the hydrothermal treatment is 70~110℃; the time of the hydrothermal treatment is 110~130min.

[0006] Preferably, the liquid-to-solid ratio of the mixture obtained by mixing the pretreated bamboo shavings with water is greater than 20.

[0007] Preferably, the temperature of the hydrothermal treatment is 85~100℃; and the time of the hydrothermal treatment is 115~125min.

[0008] Preferably, the drying temperature is 100~103℃.

[0009] The present invention also provides hydrothermal modified bamboo shavings prepared by the preparation method described in the above technical solution.

[0010] The present invention also provides a bamboo cement particleboard, wherein the raw materials for preparing the bamboo cement particleboard include: silicate cement, hydrothermal modified bamboo shavings as described in the above technical solution, and water.

[0011] This invention also provides a method for preparing the bamboo-based cement particleboard described in the above technical solution, comprising: Silicate cement, hydrothermally modified bamboo shavings, and water are mixed and then sequentially molded, pressurized, and cured to obtain bamboo cement particleboard.

[0012] Preferably, the mesh size of the hydrothermally treated modified bamboo shavings is 5 to 60 mesh.

[0013] Preferably, the mass ratio of the silicate cement to the hydrothermally modified bamboo shavings is (3~5):1.

[0014] Preferably, the mass ratio of the silicate cement to water is 1:(0.45~0.65).

[0015] This invention provides a method for preparing hydrothermally modified bamboo shavings, comprising: mixing pretreated bamboo shavings with water, subjecting them to hydrothermal treatment, and then drying them to obtain hydrothermally modified bamboo shavings; the hydrothermal treatment temperature is 70~110℃; and the hydrothermal treatment time is 110~130min. By subjecting bamboo shavings to hydrothermal treatment and limiting the temperature and time, this invention can dissolve and remove most of the water-soluble sugars in the bamboo shavings, completely volatilize formic acid, and partially volatilize acetic acid, thereby reducing the content of water-soluble sugars and organic acids in the hydrothermally modified bamboo shavings. This, in turn, facilitates the hydration reaction of silicate cement in bamboo cement particleboard prepared from hydrothermally modified bamboo shavings, improving the mechanical properties of the bamboo cement particleboard. The results of the examples show that the water-soluble sugar content in the hydrothermally modified bamboo shavings prepared by the method provided by the present invention is 2.422~2.88 g / 100g, which is 60.1~66.7% lower than that of unmodified bamboo shavings (7.225 g / 100g). The formic acid content is 0, and the acetic acid content is 45.32~145.56 mg / 100g, which is 82.5~94.5% lower than that of unmodified bamboo shavings (830.70 mg / 100g). The bamboo cement particleboard prepared using the hydrothermally modified bamboo shavings has a static bending strength of 9.04~10.17 MPa, an elastic modulus of 3025~3326 MPa, an internal bond strength of 0.31~0.51 MPa, and a 24-hour water absorption thickness expansion rate of 1.8~2.0%, exhibiting good mechanical properties and meeting the requirements for qualified and superior grade cement particleboard. Attached Figure Description

[0016] Figure 1Infrared spectra of hydrothermal modified bamboo shavings in Examples 1-3 of the present invention and bamboo shavings in Comparative Example 1. Figure 2 The X-ray diffraction patterns are of the hydrothermal modified bamboo shavings in Examples 1-3 of the present invention and the bamboo shavings in Comparative Example 1. Figure 3 The image is a scanning electron microscope image of the bamboo cement particleboard of Application Example 1 of the present invention, magnified 10,000 times. Figure 4 The image is a scanning electron microscope image of the bamboo cement particleboard of Application Example 2 of the present invention at 10,000x magnification. Figure 5 The image is a scanning electron microscope image of the bamboo cement particleboard of Application Example 3 of the present invention, magnified 10,000 times. Figure 6 The image is a scanning electron microscope image of the bamboo cement particleboard of Application Example 3 of the present invention, magnified 50 times. Detailed Implementation

[0017] This invention provides a method for preparing hydrothermally modified bamboo shavings, comprising: mixing pretreated bamboo shavings with water, subjecting the mixture to hydrothermal treatment, and then drying the mixture to obtain hydrothermally modified bamboo shavings.

[0018] In one embodiment of the present invention, the moisture content of the pretreated bamboo shavings can be 9-11% or 10%.

[0019] In one embodiment of the present invention, the pretreatment may include washing and drying; the cleaning agent used for washing may be water. The present invention does not have specific limitations on the drying temperature and time, as long as the moisture content of the pretreated bamboo shavings is controlled at 9-11%.

[0020] In one embodiment of the present invention, the length of the bamboo shavings can be 10-30mm or 15-25mm; the width of the bamboo shavings can be 1-6mm or 2-4mm; and the thickness of the bamboo shavings can be 0.2-0.4mm or 0.25-0.35mm. Limiting the size of the bamboo shavings to the above range ensures the smooth progress of subsequent hydrothermal treatment.

[0021] In one embodiment of the present invention, the liquid-to-solid ratio in the mixture obtained by mixing the pretreated bamboo shavings and water can be greater than 20, or it can be 20-40, or it can be 25-35. In the present invention, the liquid-to-solid ratio is lower than 20, resulting in poor dissolution of water-soluble sugars. The present invention limits the liquid-to-solid ratio in the mixture obtained by mixing the pretreated bamboo shavings and water to the above-mentioned range to better dissolve the water-soluble sugars in the bamboo shavings.

[0022] In one embodiment of the present invention, the hydrothermal treatment can be carried out in an adjustable temperature water boiling tank. In this invention, the temperature of the hydrothermal treatment is 70~110℃, preferably 85~100℃, more preferably 95~100℃; the time of the hydrothermal treatment is 110~130 min, preferably 115~125 min, more preferably 115~120 min. Setting the hydrothermal treatment temperature within the above range allows for the dissolution and removal of most of the water-soluble sugars contained in bamboo shavings, complete volatilization of formic acid, and partial volatilization of acetic acid, thereby reducing the content of water-soluble sugars and organic acids in the hydrothermally modified bamboo shavings. When the hydrothermal treatment temperature is below 70℃, the removal effect of harmful substances such as water-soluble sugars, formic acid, and acetic acid becomes poor, leading to a decrease in the mechanical properties of the bamboo cement particleboard.

[0023] In one embodiment of the present invention, after the hydrothermal treatment is completed, the product obtained by the hydrothermal treatment can be filtered to obtain a solid, and the solid can be dried.

[0024] In one embodiment of the present invention, the drying can be carried out in an electronic constant temperature drying oven; the drying temperature can be 100~103℃. In the present invention, the drying temperature is higher than 103℃, which will destroy the hemicellulose in the bamboo shavings and produce water-soluble sugars that affect cement hardening. The present invention sets the drying temperature within the above-mentioned range to avoid the decomposition of hemicellulose in bamboo shavings into water-soluble sugars.

[0025] The present invention does not have a special limitation on the drying time; the solid can be dried to a constant weight.

[0026] This invention involves hydrothermal treatment of bamboo shavings, with specific temperature and time limits. This process dissolves and removes most of the water-soluble sugars in the bamboo shavings, completely volatilizes formic acid, and partially volatilizes acetic acid. This reduces the content of water-soluble sugars and organic acids in the hydrothermally treated modified bamboo shavings, thereby facilitating the hydration reaction of silicate cement in bamboo cement particleboard prepared from the hydrothermally treated modified bamboo shavings and improving the mechanical properties of the bamboo cement particleboard.

[0027] The present invention also provides hydrothermal modified bamboo shavings prepared by the preparation method described in the above technical solution.

[0028] The present invention also provides a bamboo cement particleboard, wherein the raw materials for preparing the bamboo cement particleboard include: silicate cement, hydrothermal modified bamboo shavings as described in the above technical solution, and water.

[0029] This invention also provides a method for preparing the bamboo-based cement particleboard described in the above technical solution, comprising: Silicate cement, hydrothermally modified bamboo shavings, and water are mixed and then sequentially molded, pressurized, and cured to obtain bamboo cement particleboard.

[0030] In one embodiment of the present invention, the mesh size of the hydrothermal modified bamboo shavings can be 5 to 60 mesh.

[0031] In one embodiment of the present invention, when the mesh size of the hydrothermally treated modified bamboo shavings is not 5-60 mesh, the bamboo shavings that do not meet the mesh size requirement can be crushed. The present invention does not have specific limitations on the crushing process; it is sufficient to bring the mesh size of the bamboo shavings to 5-60 mesh.

[0032] In an embodiment of the present invention, the crushing process is carried out in a multi-functional crusher (2500Y); the multi-functional crusher (2500Y) was purchased from Yongkang Boou Hardware Products Co., Ltd.

[0033] In one embodiment of the present invention, the mass ratio of silicate cement to hydrothermally modified bamboo shavings can be (3~5):1, (3~4):1, or (3~3.5):1. By limiting the mass ratio of silicate cement to hydrothermally modified bamboo shavings to the above range, the present invention can fully utilize the reinforcing effect of bamboo shavings on cement particleboard.

[0034] In one embodiment of the present invention, the mass ratio of silicate cement to water can be 1:(0.45~0.65), 1:(0.5~0.6), or 1:(0.5~0.55). Limiting the mass ratio of silicate cement to water to the above range allows the cement particleboard to have better mechanical properties.

[0035] In one embodiment of the present invention, the mixing of silicate cement, hydrothermal modified bamboo shavings and water can be carried out by first mixing the hydrothermal modified bamboo shavings and water, and then adding silicate cement for a second mixing.

[0036] In an embodiment of the present invention, the first mixing time can be 2 minutes; the second mixing time can be 5 minutes.

[0037] As one embodiment of the present invention, after mixing, the mixture obtained can be shaped.

[0038] In one embodiment of the present invention, the molding can be done by hand.

[0039] In a specific embodiment of the present invention, the manual laying operation is as follows: the mixture is evenly laid on the steel pad, three slabs are laid at a time, and the three slabs together with the steel pad are stacked on the locking frame.

[0040] As one embodiment of the present invention, after molding is completed, the molded slab can be pressurized.

[0041] In one embodiment of the present invention, the pressure applied can be 4.5~6MPa or 5.0MPa.

[0042] In an embodiment of the present invention, the mold clamping frame can be cold-pressed and molded after being pressurized to a specified pressure.

[0043] In an embodiment of the present invention, the pressurization is carried out in a single-layer hot press for artificial boards (Y33-50); the single-layer hot press for artificial boards (Y33-50) was purchased from Pingxiang Jiuzhou Precision Press Co., Ltd.

[0044] As one embodiment of the present invention, after the pressurization is completed, the cold-pressed molded slab can be cured.

[0045] In one embodiment of the present invention, the maintenance can be carried out by first performing heat maintenance and then performing natural maintenance.

[0046] In one embodiment of the present invention, the temperature for heat curing can be 60~100℃ or 80~100℃; the time for heat curing can be 10~14h or 12h. By limiting the temperature and time for heat curing to the above ranges, the present invention can achieve the initial curing of bamboo-based cement particleboard.

[0047] As one embodiment of the present invention, after the heat curing is completed, the slab that was cold-pressed and molded can be depressurized and then naturally cured.

[0048] In one embodiment of the present invention, the natural curing time can be 28 days.

[0049] As one embodiment of the present invention, the cured bamboo cement particleboard can be dried after the curing is completed.

[0050] In one embodiment of the present invention, the drying temperature can be 70~100℃ or 90~100℃.

[0051] The present invention does not have a special limitation on the drying time. The moisture content of the bamboo cement particleboard can be dried to 9-11% using the time commonly used by those skilled in the art.

[0052] In an embodiment of the present invention, the drying is carried out in an electronic constant temperature drying oven (101A); the electronic constant temperature drying oven (101A) was purchased from Shanghai Experimental Instrument Factory.

[0053] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0054] In all embodiments and application examples of the present invention, the raw materials used are: bamboo shavings, purchased from Hunan Taohuajiang Industrial Co., Ltd., with a moisture content of 10%, a length of 10~30mm, a width of 1~6mm, and a thickness of 0.2~0.4mm; and silicate cement, R52.5, purchased from Zhucheng Yangchun Cement Co., Ltd.

[0055] Example 1 A method for preparing hydrothermally modified bamboo shavings is as follows: bamboo shavings with a mesh size of 5-60 are pretreated by washing with water and drying until the moisture content of the bamboo shavings is 10%. Then, the pretreated bamboo shavings and water are added to an adjustable temperature water boiling tank at a liquid-to-solid ratio of 20 and hydrothermally treated at 70°C for 120 minutes. The product obtained from the hydrothermal treatment is filtered to obtain a solid. The solid is dried at 103°C in an electronic constant temperature drying oven to constant weight to obtain hydrothermally modified bamboo shavings.

[0056] Example 2 The only difference between Example 2 and Example 1 is that the hydrothermal treatment temperature is 85°C. Otherwise, they are the same as in Example 1, and hydrothermal modified bamboo shavings are obtained.

[0057] Example 3 The only difference between Example 3 and Example 1 is that the hydrothermal treatment temperature is 100℃, and everything else is the same as in Example 1, resulting in hydrothermally modified bamboo shavings.

[0058] Comparative Example 1 Comparative Example 1 was not subjected to hydrothermal treatment, but otherwise the same as Example 1, resulting in bamboo shavings (referred to as untreated).

[0059] Application Example 1 A bamboo cement particleboard, wherein the raw materials for preparing the bamboo cement particleboard are: silicate cement, hydrothermal modified bamboo shavings as described in Example 1, and water; The method for preparing the bamboo-based cement particleboard is as follows: Hydrothermal-treated modified bamboo shavings (mesh size 5-60 mesh) and water are first mixed for 2 minutes, then silicate cement is added and mixed for a second time for 5 minutes to obtain a mixture. The mixture is evenly spread on a steel plate, with three slabs laid at a time. The three slabs, along with the steel plate, are stacked on a locking frame and then placed in a cold press for pressurization. After pressurization to 5 MPa, the locking frame is cold-pressed and locked. The cold-pressed slabs are then sent to a curing chamber for heat curing at 100℃ for 12 hours. After heat curing, the cold-pressed slabs are depressurized and naturally cured for 28 days. Finally, they are dried in a 100℃ oven until the moisture content is 10% to obtain bamboo cement particleboard. The mass ratio of silicate cement to hydrothermal-treated modified bamboo shavings is 3:1, and the mass ratio of silicate cement to water is 1:0.5.

[0060] Application Example 2 A bamboo cement particleboard, wherein the raw materials for preparing the bamboo cement particleboard are: silicate cement, hydrothermal modified bamboo shavings as described in Example 2, and water; The preparation method of the bamboo cement particleboard is the same as in Application Example 1.

[0061] Application Example 3 A bamboo cement particleboard, wherein the raw materials for preparing the bamboo cement particleboard are: silicate cement, hydrothermal modified bamboo shavings as described in Example 3, and water; The preparation method of the bamboo cement particleboard is the same as in Application Example 1.

[0062] Comparative Application Example 1 A bamboo cement particleboard, wherein the raw materials for preparing the bamboo cement particleboard are: silicate cement, bamboo shavings as described in Comparative Example 1, and water; The preparation method of the bamboo cement particleboard is the same as in Application Example 1.

[0063] Test case (I) Detection of water-soluble sugars and organic acids: Water-soluble sugars and organic acids in hydrothermally modified bamboo shavings were detected by high-performance liquid chromatography (HPLC) using a Waters 244 (Waters Corporation, USA), a Diamonsil C18 column (250×4.6mm), a Waters 486 differential detector, an M510 pump, a six-way valve injector, and a Zhejiang University 2000 chromatography workstation. Parameter settings: mobile phase: 0.05 mol / L H2SO4 (V:V), temperature: 55℃, flow rate: 0.01 mL / min; water was double-distilled and filtered through a 0.45 µm filter membrane; acetonitrile was chromatographically pure; methanol was analytical grade and filtered through a 0.51 µm filter membrane; phosphoric acid was analytical grade.

[0064] The hydrothermally modified bamboo shavings from Examples 1-3 and the bamboo shavings from Comparative Example 1 were pulverized using a multi-functional pulverizer and then screened through a vibrating sieve to obtain 200-mesh bamboo powder. 5g of each bamboo powder sample was weighed, added with distilled water, and soaked at room temperature for 24 hours. The samples were then centrifuged at 4000 rpm for 25 minutes. Three 20µL supernatants were taken and analyzed by high-performance liquid chromatography (HPLC) under the above chromatographic conditions to obtain chromatograms of free sugars and free organic acids. The injection was repeated three times, and the peak areas were calculated using the area normalization method. The contents were calculated using the external standard method. The water-soluble sugar content, types and contents of organic carboxylic acids in the hydrothermally modified bamboo shavings from Examples 1-3 and the bamboo shavings from Comparative Example 1 are shown in Table 1.

[0065] Table 1 shows the water-soluble sugar content, types and contents of organic carboxylic acids in the hydrothermal modified bamboo shavings of Examples 1-3 and the bamboo shavings of Comparative Example 1.

[0066] As shown in Table 1, formic acid was not detected in the hydrothermal modified bamboo shavings of Examples 1-3, but water-soluble sugars and acetic acid were present in varying amounts. The water-soluble sugar content per 100g of bamboo shavings from Comparative Example 1, Example 1, Example 2, and Example 3 was 7.225g, 2.880g, 2.732g, and 2.422g, respectively, and the acetic acid content was 830.7mg, 145.56mg, 95.67mg, and 45.32mg, respectively. Therefore, hydrothermal treatment can completely remove formic acid from bamboo shavings and reduce the content of water-soluble sugars in bamboo shavings. However, different hydrothermal treatment temperatures have little effect on the water-soluble sugar content in bamboo shavings. Compared with the untreated bamboo shavings in Comparative Example 1, the water-soluble sugar content in the hydrothermally treated bamboo shavings of Example 1, Example 2, and Example 3 decreased by 60.1%, 62.2%, and 66.7%, respectively. Hydrothermal treatment can significantly reduce the acetic acid content in bamboo shavings, and the higher the hydrothermal treatment temperature, the more significant the reduction in acetic acid content. Compared with the untreated bamboo shavings in Comparative Example 1, the acetic acid content in the hydrothermally treated bamboo shavings of Example 1, Example 2, and Example 3 decreased by 82.5%, 88.5%, and 94.5%, respectively.

[0067] (II) Fourier Transform Infrared Spectroscopy (FTIR): The potassium bromide pellet method was used. A Fourier Transform Infrared Spectrometer (IRAffinity-1, Shimadzu Corporation, Japan) was used to scan and analyze the surface functional groups of the bamboo powder prepared from the hydrothermally modified bamboo shavings of Examples 1-3 and the bamboo shavings of Comparative Example 1. The scanning range was 4000~400 cm⁻¹. -1 Resolution: 2cm -1 Number of scans: 32, repeated once.

[0068] The infrared spectra of the hydrothermal modified bamboo shavings in Examples 1-3 and the bamboo shavings in Comparative Example 1 are as follows: Figure 1 As shown, from Figure 1 As can be seen, the infrared characteristic peaks and their assignments in bamboo shavings before and after hydrothermal treatment are basically consistent, and the positions of the characteristic peaks of each functional group also remain largely unchanged. This indicates that hydrothermal treatment did not generate new chemical bonds, and therefore no new characteristic peaks were produced in the infrared spectrum. The reason for the above high-performance liquid chromatography (HPLC) analysis results may be that the hydrothermal treatment process caused some water-soluble sugars and acetic acid in the bamboo shavings to dissolve, resulting in a decrease in their content. In addition, formic acid is a highly volatile carboxylic acid, and it may have evaporated rapidly during the hydrothermal treatment of bamboo shavings, so formic acid was not detected.

[0069] from Figure 1 It can also be found that 897cm -1 and 3304cm -1 The characteristic peaks of cellulose in the vicinity did not change before and after hydrothermal treatment of bamboo shavings, while the peaks of bamboo shavings in Comparative Example 1 and Examples 1-3 remained unchanged before and after hydrothermal treatment at 2900 cm⁻¹. -1 The characteristic peaks of cellulose in the vicinity show a slight decrease in the characteristic peak of the hydrothermally modified bamboo shavings treated at 100℃ in Example 3. This indicates that low-temperature hydrothermal treatment (the hydrothermal modified bamboo shavings treated at 70℃ in Example 1 and at 85℃ in Example 2) does not destroy the cellulose in the bamboo shavings. However, when the hydrothermal treatment temperature is increased to 100℃, the hydrothermal effect will cause slight damage to some of the cellulose in the bamboo shavings. (1021 cm⁻¹) -1 and 1506cm -1 These are characteristic peaks of lignin. In Comparative Example 1 (untreated) and in Examples 1-3 (treated), these two characteristic peaks did not change, indicating that the hydrothermal treatment temperature and time did not cause damage to the lignin in the bamboo shavings. (1730cm) -1The acetyl and carbonyl stretching vibration peaks of the nearby bamboo hemicellulose remained largely unchanged, indicating that the temperature and time of hydrothermal treatment did not significantly damage the bamboo hemicellulose. Therefore, the hydrothermal treatment temperature and time do not substantially alter the chemical composition of bamboo shavings. Consequently, it is unlikely that hydrothermal treatment would produce water-soluble sugars and carboxylic acids in bamboo shavings that have an "anti-setting" effect on silicate cement; on the contrary, it might dissolve or remove some of these "anti-setting" water-soluble sugars and carboxylic acids.

[0070] (III) X-ray diffraction (XRD) using a model XD-2 (purchased from Beijing Purkinje General Instrument Co., Ltd.): The crystallization properties of bamboo powder prepared from the hydrothermal modified bamboo shavings of Examples 1-3 and Comparative Example 1 were tested and analyzed. Test conditions: CuKα target (λ=0.154nm), voltage 40kV, current 35mA, scanning speed 2θ=8° / min, scanning range 5~45°.

[0071] The X-ray diffraction patterns of the hydrothermal modified bamboo shavings in Examples 1-3 and the bamboo shavings in Comparative Example 1 are shown below. Figure 2 As shown, from Figure 2 As can be seen from the X-ray diffraction pattern, the positions of the characteristic diffraction peaks 101, 002, and 004 of bamboo cellulose near 2θ=16.05°, 21.5°, and 34.5° remained essentially unchanged, and the peak height and width also showed very small changes. This indicates that hydrothermal treatment had virtually no effect on either the crystalline or non-crystalline regions of cellulose in the bamboo cell wall. Therefore, it is evident that the hydrothermal treatment temperatures of 70℃ in Example 1, 85℃ in Example 2, and 100℃ in Example 3 did not significantly damage the cellulose, hemicellulose, and lignin in the bamboo cell wall, thus failing to produce new hydrolysis products. This is consistent with the results of Fourier transform infrared spectroscopy analysis.

[0072] (iv) Mechanical property testing: The physical and mechanical properties of the bamboo cement particleboard corresponding to Examples 1-3 and Comparative Application Example 1 were tested in accordance with the national standard for cement particleboard (GB / T 24312-2009). The static bending strength (MOR), modulus of elasticity (MOE), internal bond strength (IB), and 24-hour thickness expansion rate (TS) of the specimens were tested using a DCS-R-1 million kcal / m³ mechanical testing machine from Tsushima Corporation, Japan, according to the GB / T 24312-2009 standard for cement particleboard.

[0073] The mechanical property data of bamboo cement particleboard used in Application Examples 1-3 and Comparative Application Example 1 are shown in Table 2.

[0074] Table 2 shows the mechanical properties of bamboo-based cement particleboard used in Application Examples 1-3 and Comparative Application Example 1.

[0075] As shown in Table 2, the mechanical properties of the bamboo cement particleboard in Application Examples 1-3 are significantly better than those in Comparative Application Example 1, indicating that hydrothermal treatment has a certain effect on improving the compatibility between bamboo shavings and silicate cement. The static bending strength (MOR), modulus of elasticity (MOE), and internal bond strength (IB) of the bamboo cement particleboard in Comparative Application Example 1 also failed to meet the national standard requirements for qualified cement particleboard. However, the static bending strength (MOR), modulus of elasticity (MOE), internal bond strength (IB), and 24-hour water absorption thickness expansion rate (TS) values ​​of the bamboo cement particleboard in Application Examples 1 and 2 all meet the requirements for qualified cement particleboard. The performance of the bamboo cement particleboard in Application Example 3 meets the requirements for superior grade. The results show that simply hydrothermal treatment of bamboo can completely solve the "anti-coagulation" effect of water-soluble sugars and carboxylic acids in bamboo on silicate cement. As the hydrothermal treatment temperature increases from 70℃ to 85℃ and 100℃, the total content of water-soluble sugars and carboxylic acids in bamboo shavings gradually decreases, and the mechanical properties of bamboo cement particleboard gradually improve.

[0076] (v) Scanning electron microscopy (SEM): The cross-sectional morphology of the bamboo cement particleboard sprayed with gold in Examples 1-3 was observed using a MIRA3LMH scanning electron microscope (purchased from Tesco China Ltd.). The test pressure was 0.8MPa and the test voltage was 15KV.

[0077] The scanning electron microscope image of bamboo-cement particleboard in Application Example 1 at 10,000x magnification is shown below. Figure 3 As shown, the scanning electron microscope image of the bamboo-cement particleboard from Application Example 2 at 10,000x magnification is as follows. Figure 4 As shown, the scanning electron microscope image of the bamboo-cement particleboard from Application Example 3 at 10,000x magnification is as follows. Figure 5 As shown, the scanning electron microscope image at 50x magnification is as follows: Figure 6 As shown.

[0078] The main components of silicate cement are tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite. Its main hydration products include CSH gel, Ca(OH)₂, trisulfide-type hydrated calcium sulfoaluminate (ettringite, Aft), and monosulfide-type hydrated calcium sulfoaluminate (AFm). CSH gel exhibits irregular flocculent, needle-like, columnar, rod-like, fibrous, and coral-like morphologies, playing a dominant role in the strength development of the hydration products; Ca(OH)₂ forms hexagonal plate-like crystals; Aft forms in the early stages of hydration, initially as rod-shaped crystals with straight, unbranched ends; AFm grows in irregular plate-like clusters or in a flower-like pattern, eventually transforming into hexagonal plates.

[0079] from Figures 3-6It can be seen that the cross-sections of the bamboo cement particleboards in Application Examples 1-3 all showed varying amounts of hydration products with irregular flocculent, coral-like, needle-like, columnar, and rod-like characteristics. This is presumably due to the silicate cement hydration reaction in the bamboo cement particleboard producing CSH and Aft, but almost no plate-like Ca(OH)2 and AFm were found. Compared to the bamboo cement particleboard in Application Example 2, the morphology and quantity of hydration products in the bamboo cement particleboard of Application Example 1 did not change significantly. However, in the bamboo cement particleboard of Application Example 3, the irregular flocculent and coral-like silicate cement hydration products were significantly increased, and the density was also increased, indicating that the hydration reaction in the bamboo cement particleboard of Application Example 3 was more extensive, producing more CSH components that play a dominant role in the strength development of hydration products, resulting in better mechanical properties of the cement particleboard. This is because the 100℃ hydrothermal treatment further reduced the "anti-setting" components of water-soluble sugars and carboxylic acids in the bamboo shavings. Meanwhile, from... Figure 6 It can be seen that hydrothermal modified bamboo shavings and silicate cement hydration products form a certain bonding interface, but this does not affect the strength of the structural material.

[0080] The hydrothermal-treated modified bamboo shavings prepared by the method provided in this invention have a water-soluble sugar content of 2.422~2.88 g / 100g, which is 60.1~66.7% lower than the 7.225 g / 100g of unmodified bamboo shavings. The formic acid content is 0, and the acetic acid content is 45.32~145.56 mg / 100g, which is 82.5~94.5% lower than the acetic acid content of 830.70 mg / 100g of unmodified bamboo shavings. The bamboo-based cement particleboard prepared using this hydrothermal-treated modified bamboo shavings has a static bending strength of 9.04~10.17 MPa, an elastic modulus of 3025~3326 MPa, an internal bond strength of 0.31~0.51 MPa, and a 24-hour water absorption thickness expansion rate of 1.8~2.0%, exhibiting good mechanical properties and meeting the requirements for qualified and superior grade cement particleboard products.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing hydrothermally modified bamboo shavings, comprising: Pretreated bamboo shavings were mixed with water, subjected to hydrothermal treatment, and then dried to obtain hydrothermally modified bamboo shavings. The temperature of the hydrothermal treatment is 70~110℃; the time of the hydrothermal treatment is 110~130min.

2. The preparation method according to claim 1, characterized in that, The liquid-to-solid ratio of the mixture obtained by mixing the pretreated bamboo shavings with water is greater than 20.

3. The preparation method according to claim 1, characterized in that, The hydrothermal treatment temperature is 85~100℃; the hydrothermal treatment time is 115~125min.

4. The preparation method according to claim 1, characterized in that, The drying temperature is 100~103℃.

5. The hydrothermally modified bamboo shavings prepared by the preparation method according to any one of claims 1 to 4.

6. A bamboo-based cement particleboard, characterized in that, The raw materials for preparing the bamboo cement particleboard include: silicate cement, hydrothermal modified bamboo shavings as described in claim 5, and water.

7. The method for preparing the bamboo-based cement particleboard according to claim 6, comprising: Silicate cement, hydrothermally modified bamboo shavings, and water are mixed and then sequentially molded, pressurized, and cured to obtain bamboo cement particleboard.

8. The preparation method according to claim 7, characterized in that, The mesh size of the hydrothermally treated modified bamboo shavings is 5-60 mesh.

9. The preparation method according to claim 7, characterized in that, The mass ratio of silicate cement to hydrothermally modified bamboo shavings is (3~5):

1.

10. The preparation method according to claim 7, characterized in that, The mass ratio of the silicate cement to water is 1:(0.45~0.65).

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