Preparation method of high mechanical property starch-based hydrogel and application in wood bonding

Abstract

This invention provides a method for preparing a high-mechanical-performance starch-based hydrogel and its application in wood bonding, belonging to the field of adhesive technology. The invention involves uniformly mixing starch and MCC, gelatinizing the mixture, and then soaking it in a calcium chloride solution to obtain the high-mechanical-performance starch-based hydrogel. This high-mechanical-performance starch-based hydrogel possesses excellent adhesive properties. After shearing, it is coated onto the surface of wood and hot-pressed to achieve wood bonding; its adhesive strength reaches up to 10.228 MPa, and it can maintain good adhesive strength even in extreme environments, showing broad application prospects. Furthermore, the preparation process of this invention is simple, efficient, and environmentally friendly, requiring no high-temperature, long-term heating, pH adjustment, or additional chemical crosslinking agents, thus meeting the needs of efficient industrial production of wood bonding.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a method for preparing a starch-based hydrogel with high mechanical properties and its application in wood bonding. Background Technology

[0002] Currently, commonly used adhesives mainly include petroleum-based synthetic adhesives (such as urea-formaldehyde resin, polyvinyl alcohol, hot melt adhesives, etc.) and traditional water-based / bio-based adhesives (such as white glue, acrylic glue, natural starch glue, etc.). Among these, petroleum-based synthetic adhesives (such as epoxy and polyurethane) primarily consist of long-chain or network structures formed by the polymerization of non-renewable petrochemical monomers. To adjust processing performance, volatile organic solvents or residual toxic monomers (such as formaldehyde and free isocyanates) are often added. These low-molecular-weight substances are released before and after curing, leading to volatile organic compound pollution and health risks. Furthermore, their polymer backbone is difficult to degrade in the natural environment, easily causing soil pollution. Traditional water-based / bio-based adhesives, on the other hand, have numerous hydrophilic groups on their polysaccharide or protein molecular chains that easily bind with water molecules, causing the network structure to swell and break down. Moreover, the monomolecular physical cross-linked network structure formed by interactions such as hydrogen bonds between molecular chains lacks toughness and stability. Currently, both types of adhesive substrates have certain defects in existing technologies. For example, petroleum-based synthetic rubbers generally suffer from environmental pollution (non-degradable), non-renewable raw materials, some toxic and harmful substances, and poor brittleness or heat resistance; traditional water-based / bio-based rubbers suffer from poor water resistance (easily swells and breaks), insufficient mechanical properties, and poor physical stability. [1] .

[0003] To address the aforementioned issues, this invention utilizes the synergistic effect of microcrystalline cellulose (MCC) reinforcement and controllable ionic crosslinking coordination to reconstruct and strengthen the network strength of starch-based gels at the microstructural level. This effectively improves the mechanical strength and physical stability of starch-based adhesives, providing a novel, environmentally friendly, green, safe, and renewable alternative for sustainable development. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing a starch-based hydrogel with high mechanical properties and its application in wood bonding. This invention utilizes the synergistic effect of microcrystalline cellulose (MCC) reinforcement and controllable ionic crosslinking coordination to reconstruct and strengthen the network strength of the starch-based gel at the microstructural level. This effectively improves the mechanical strength and physical stability of starch-based adhesives, overcoming the common defects of traditional starch-based adhesives, which mainly rely on hydrogen bonding interactions to form monomolecular crosslinked networks, resulting in low mechanical strength and low viscosity.

[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a starch-based hydrogel with high mechanical properties, comprising the following steps:

[0007] MCC powder was dispersed in deionized water and ultrasonically stirred at room temperature for 15 min to obtain an MCC suspension.

[0008] Starch is added to the MCC suspension and mixed evenly to obtain a mixture solution; the mass ratio of starch to MCC is (90%-50%):(10%-50%).

[0009] The mixture solution was gelatinized, cooled, and then soaked in a calcium chloride solution to obtain a starch-based hydrogel with high mechanical properties.

[0010] Furthermore, the preparation process of the MCC suspension is as follows: MCC powder is added to deionized water and stirred vigorously for 5-30 minutes under ultrasonic conditions at room temperature to prevent MCC from agglomerating, thereby obtaining the MCC suspension; the ratio of the amount of deionized water to the total mass of MCC and starch is (1-2):1.

[0011] Further, after adding starch to the MCC suspension, stir under ultrasonic conditions at room temperature for 1-10 min, and then stir on a magnetic stirring table at a speed of 800-1200 rpm for 10-60 min to ensure thorough mixing and obtain a mixture solution.

[0012] Furthermore, the starch includes, but is not limited to, one or more of potato starch, pea starch, mung bean starch, corn starch, wheat starch, sweet potato starch, and cassava starch.

[0013] Further, the gelatinization process is as follows: the mixture solution is poured into a silicone mold (length * width * thickness = 8cm * 2cm * 0.2cm) and steamed in a steamer at a power of 900-1200W for 4-5 minutes.

[0014] Furthermore, the concentration of the calcium chloride solution is 1-5 mol / L.

[0015] Furthermore, the soaking treatment time is 10-100 min.

[0016] In a second aspect, the present invention provides a starch-based hydrogel with high mechanical properties prepared by the aforementioned preparation method.

[0017] A third aspect of the present invention provides a method for applying the high-mechanical-performance starch-based hydrogel in wood bonding, comprising: shearing the high-mechanical-performance starch-based hydrogel and then coating it onto the interface of the substrate to be bonded, followed by hot pressing to achieve wood bonding. The high-mechanical-performance starch-based hydrogel can be sheared before use, followed by coating and bonding; alternatively, the high-mechanical-performance starch-based hydrogel can be pre-sheared and stored, and then directly coated onto the interface of the substrate to be bonded when needed.

[0018] Furthermore, the shearing process takes 5-10 minutes.

[0019] Furthermore, the coating amount of the starch-based hydrogel is 50-250 g / m². 2 .

[0020] Furthermore, the process parameters for the hot pressing treatment are: temperature: 120-180 ℃, time: 10-90 min, pressure: 1-1.2 MPa.

[0021] Existing starch-based adhesives are generally suitable for paper products such as cardboard boxes and corrugated boards, but they do not take into account the porous, highly absorbent, and demanding interfacial bonding characteristics of wood. This leads to uneven curing and debonding of the adhesive due to moisture migration, and the lack of enhanced interfacial bonding makes it unsuitable for cutting, sanding, and load-bearing scenarios in wood processing. This invention focuses on the core pain points of starch-based wood adhesives, specifically optimizing the process: preserving the integrity of the composite structure of starch and MCC, resulting in a stronger adhesive viscosity that can penetrate wood pores to form a strong "mechanical interlocking" structure without being lost due to excessive flow; and replacing the chemical modification or cross-linking agent addition of existing technologies with a calcium chloride solution soaking process. Through the strong ionic coordination between calcium ions and the hydroxyl groups of starch and MCC, a dense and stable three-dimensional network structure is constructed, effectively reducing the moisture absorption rate of the composite adhesive in humid environments and preventing cracking or debonding caused by moisture penetration or migration after wood bonding, precisely addressing the core problem of wood bonding.

[0022] This invention relates to a high-mechanical-performance starch-based hydrogel, which uses starch (widely available, low-cost, and requiring no complex purification processes) and MCC (easy to prepare and highly stable) in an appropriate ratio. Through physical mixing and uniform dispersion, it avoids problems such as easy agglomeration and difficulty in dehydration. Furthermore, the raw material combination focuses on enhancing adhesive strength, making it suitable for the porous nature of wood and its requirement for high adhesion. The starch-MCC composite system exhibits good wettability and can penetrate the nanopores of wood. The strong cross-linked structure formed after calcium chloride soaking reduces moisture loss, preventing wood deformation or adhesive failure due to moisture absorption. Simultaneously, the fibrous structure of MCC enhances interfacial forces and improves adhesive durability. Using MCC as a raw material effectively solves the problems of high preparation cost and difficulty in dispersion of starch-based adhesives. The mixing uniformity of MCC and starch is good, requiring no complex dispersion process. MCC has high crystallinity and excellent mechanical properties, and when combined with starch, it enhances the interfacial bonding force of starch-based adhesives. Compared to microfibrillated cellulose (MFC), the MCC of this invention is more likely to form physical entanglement (interlocking) with wood fibers, which is more conducive to significantly improving the bonding strength; the appropriate compounding ratio of starch and MCC takes into account both adhesion and processability, avoids coating difficulties caused by excessive MCC content, and adapts to the uneven characteristics of wood surface.

[0023] The process of this invention requires only two steps, without the need for high-temperature and long-term heating, pH adjustment, or additional chemical crosslinking agents (the use of chemical crosslinking agents and high pH adjustment in the prior art will damage the fiber structure of wood and seriously reduce the bonding strength of wood). It has the advantages of being simple, green, environmentally friendly, safe, low in energy consumption, and highly efficient. Moreover, the soaking process allows calcium ions to fully penetrate, enhancing the density and stability of the gel network, which is suitable for the industrialized and efficient production needs of wood bonding.

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

[0025] This invention constructs a uniform ion-physical synergistic network through a simple and controllable process, directly and specifically producing three significant and effective effects: structural homogenization, synergistic performance enhancement, and efficient and controllable process. Compared with existing technologies that rely solely on physical blending or simple ion crosslinking for reinforcement, this invention, by introducing the synergistic effect of rigid MCC filling and uniformly distributed calcium ion coordination bonds, constructs a dual-reinforcement network with both rigidity and flexibility at the microscopic level. This network structure directly produces the following significant effects: MCC, as a nano-skeleton, bears the main mechanical stress, significantly improving the tensile strength and toughness of the starch-based gel; simultaneously, the uniform and stable ion crosslinking bonds not only serve as strong connection points but also effectively block the penetration and swelling of water molecules into the hydrophilic groups of starch, resulting in a breakthrough improvement in the physical stability and adhesive strength retention rate of the starch-based composite gel in humid environments. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the preparation method of the high mechanical property starch-based hydrogel of the present invention;

[0027] Figure 2 The rehydration characteristics test results are for PSMCa-1 to PSMCa-5 prepared in Example 1, PSN prepared in Comparative Example 1, PSMCa prepared in Comparative Example 2, and PSM prepared in Comparative Example 3; among them, Figure 2 A represents the rehydration time; Figure 2 B represents the rehydration rate; Figure 2 C represents the cooking loss rate;

[0028] Figure 3 The tensile and shear properties test results of PSMCa-1~PSMCa-5 prepared in Example 1, PSN prepared in Comparative Example 1, PSMCa prepared in Comparative Example 2, and PSM prepared in Comparative Example 3 are shown below; Figure 3 A represents the tensile stress-strain curve; Figure 3 B represents the shear toughness diagram;

[0029] Figure 4 The physical stability test results are for PSMCa-1 to PSMCa-5 prepared in Example 1 and PSN prepared in Comparative Example 1; wherein, Figure 4 A represents the swelling rate at different treatment times; Figure 4 B represents the shrinkage rate under different treatment times;

[0030] Figure 5 Photos of the antifreeze properties of PSMCa-3 prepared in Example 1 and PSN prepared in Comparative Example 1.

[0031] Figure 6 DSC curves of PSMCa-3 prepared in Example 1, PSN prepared in Comparative Example 1, and PSMCa prepared in Comparative Example 2;

[0032] Figure 7 The water retention performance test results of PSMCa-3 prepared in Example 1 and PSN prepared in Comparative Example 1 under different conditions (temperature and humidity);

[0033] Figure 8 The adhesion performance test results of PSMCa-3 prepared in Example 1 on foam (A), plastic (B), steel (C), paper (D), wood (E), rubber (F), blade (G) and glass (H) are shown.

[0034] Figure 9 The test results for lifting heavy objects using PSMCa-3 prepared in Example 1;

[0035] Figure 10The adhesion performance test results of PSMCa-3 prepared in Example 1 on the wrist, fingers, elbow and knee;

[0036] Figure 11 The test results of PSMCa-3 prepared in Example 1 being repeatedly adhered to the skin surface in a cycle.

[0037] Figure 12 The adhesive strength test results are for PSMCa-3 prepared in Example 1; wherein, Figure 12 A is a schematic diagram of the adhesive strength test; Figure 12 B represents the adhesive strength test results for different coating amounts under a hot-pressing process at a temperature of 140 ℃, a time of 30 min, and a pressure of 1-1.2 MPa. Figure 12 C represents a fixed coating weight of 200 g / m². 2 Adhesion strength test results under different hot pressing processes;

[0038] Figure 13 Vertical (A) and horizontal (B) tensile test diagrams of the PSMCa-3 bonded wood prepared in Example 1;

[0039] Figure 14 The bonding strength test results of the PSMCa-3 bonded wood prepared in Example 1 after exposure to different environments for 12 h;

[0040] Figure 15 The tensile properties test results are for the starch-based hydrogel prepared in Example 2; wherein, Figure 15 A is the stress-strain curve of starch-based hydrogels prepared by soaking in 1M calcium chloride solution for different times; Figure 15 B is the stress-strain curve of starch-based hydrogels prepared by soaking in 3M calcium chloride solution for different times; Figure 15 C represents the stress-strain curves of starch-based hydrogels prepared by soaking in 5M calcium chloride solution for different times;

[0041] Figure 16 The mechanical property test results are for the different starch-based hydrogels prepared in Example 3; wherein, Figure 16 A is the tensile stress-strain curve of the pea starch-based hydrogel; Figure 16 B is the tensile stress-strain curve of mung bean starch-based hydrogel; Figure 16 C represents the tensile stress-strain curve of the corn starch-based hydrogel; Figure 16 D is the tensile stress-strain curve of wheat starch-based hydrogel; Figure 16 E represents the tensile stress-strain curve of the sweet potato starch-based hydrogel. Figure 16 F represents the tensile stress-strain curve of the cassava starch-based hydrogel. Detailed Implementation

[0042] To enable those skilled in the art to clearly and completely understand the technical solution of the present invention, the present invention will be further described in detail below with reference to embodiments. Obviously, the embodiments described herein are only for explaining the present invention and are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0043] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in this invention are conventional reagents, methods and equipment in the art.

[0044] This invention provides a method for preparing a starch-based hydrogel with high mechanical properties, comprising the following steps:

[0045] Add MCC to deionized water and stir vigorously for 5-30 minutes under ultrasonic conditions at room temperature to prevent MCC from agglomerating, thereby obtaining an MCC suspension; the ratio of the amount of deionized water to the total mass of MCC and starch is (1-2):1.

[0046] Add starch to the MCC suspension and stir under ultrasonic conditions at room temperature for 1-10 min. Then stir on a magnetic stirring table at a speed of 800-1200 rpm for 10-60 min to ensure thorough mixing and obtain a mixture solution. The mass ratio of starch to MCC is (90%-50%):(10%-50%).

[0047] The mixture solution is poured into a silicone mold (length * width * thickness = 8 cm * 2 cm * 0.2 cm), steamed in a steamer at 900-1200 W for 4-5 minutes, cooled to room temperature, and then immersed in a 1-5 mol / L calcium chloride solution for 10-100 minutes to obtain a high-mechanical-performance starch-based hydrogel. When applying this high-mechanical-performance starch-based hydrogel to wood bonding, it is first sheared, then coated onto the interface of the substrate to be bonded, and finally hot-pressed to achieve wood bonding.

[0048] In some examples, the starch includes, but is not limited to, one or more of potato starch, pea starch, mung bean starch, corn starch, wheat starch, sweet potato starch, and cassava starch.

[0049] In some examples, the shearing process takes 5-10 minutes.

[0050] In some examples, the coating amount of the starch-based hydrogel is 50-250 g / m³.2 .

[0051] In some examples, the process parameters for the hot pressing treatment are: temperature: 120-180 ℃, time: 10-90 min, pressure: 1-1.2 MPa.

[0052] In the following specific embodiments, the potato starch was purchased from Gansu Lantian Potato Industry Co., Ltd. (Gansu, China; 20230703); the pea starch was purchased from Fujian Shuanglong Food Co., Ltd. (Fujian, China; 20230210); the mung bean starch was purchased from Yantai Shuangta Food Co., Ltd. (Yantai, China; 20210917); the corn starch was purchased from Xinxiang Liangrun Whole Grain Food Co., Ltd. (Xinxiang, China; 20210823); the wheat starch was purchased from Xinxiang Liangrun Whole Grain Food Co., Ltd. (Xinxiang, China; 20210823); the sweet potato starch was purchased from Shandong Liuliushun Food Co., Ltd. (Shandong, China; 20210811); the cassava starch was purchased from Xinxiang Liangrun Whole Grain Food Co., Ltd. (Xinxiang, China; 20210823); and the MCC was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. (CAS: 9004-34-6).

[0053] Example 1: Effect of different MCC ratios on starch-based hydrogels with high mechanical properties

[0054] The preparation steps of the high mechanical property starch-based hydrogel in this embodiment are as follows:

[0055] (1) Preparation of MCC suspension: Weigh MCC powder, add deionized water in the ratio of total mass of MCC and starch to deionized water = 1:2, stir vigorously for 15 min under ultrasonic conditions at room temperature to prevent MCC from agglomerating, and obtain MCC suspension.

[0056] (2) Preparation of mixture solution: Potato starch was added to the MCC suspension and stirred for 5 min under ultrasonic conditions at room temperature. Then, a magnetic rotor was added and sealed. The mixture was stirred for 40 min at 1000 rpm on a magnetic stirring table to obtain the mixture solution. The mass ratio of potato starch to MCC was 90%:10%, 80%:20%, 70%:30%, 60%:40%, and 50%:50%, respectively.

[0057] (3) Gelatinization: Pour the mixture solution into a silicone mold (length*width*thickness = 8 cm*2 cm*0.2 cm), steam it in a steamer at 1200 W for 4 min, and cool it to room temperature.

[0058] (4) Crosslinking: The mixture cooled to room temperature was immersed in 3M calcium chloride solution for 40 min to obtain starch-based hydrogels with high mechanical properties. The residual calcium chloride solution on the surface of the hydrogel was wiped off with a lint-free cloth and labeled as PSMCa-1 (MCC percentage 10%), PSMCa-2 (MCC percentage 20%), PSMCa-3 (MCC percentage 30%), PSMCa-4 (MCC percentage 40%), and PSMCa-5 (MCC percentage 50%).

[0059] Comparative Example 1

[0060] A purely natural starch-based hydrogel is prepared as follows:

[0061] (1) Add potato starch to deionized water at a ratio of 1:2 (mass of potato starch: deionized water), stir for 5 min under ultrasonic conditions at room temperature, then add a magnetic rotor and seal it, and continue stirring at 1000 rpm for 40 min on a magnetic stirring table to obtain potato starch solution.

[0062] (2) Pour the potato starch solution into a silicone mold (length * width * thickness = 8 cm * 2 cm * 0.2 cm), steam it in a steamer at 1200 W for 4 min, and cool it to room temperature to obtain a pure natural starch-based hydrogel, denoted as PSN.

[0063] Comparative Example 2

[0064] A starch-based hydrogel is prepared by the following steps:

[0065] (1) Add potato starch to deionized water at a ratio of 1:2 (mass of potato starch: deionized water), stir for 5 min under ultrasonic conditions at room temperature, then add a magnetic rotor and seal it, and continue stirring at 1000 rpm for 40 min on a magnetic stirring table to obtain potato starch solution.

[0066] (2) Pour the potato starch solution into a silicone mold (length * width * thickness = 8 cm * 2 cm * 0.2 cm), steam it in a steamer at 1200 W for 4 minutes, and then cool it to room temperature.

[0067] (3) The substance cooled to room temperature was immersed in 3M calcium chloride solution for 40 min to obtain starch-based hydrogel. The residual calcium chloride solution on the surface of the hydrogel was wiped off with a lint-free cloth and denoted as PSCa.

[0068] Comparative Example 3

[0069] A starch-based hydrogel is prepared by the following steps:

[0070] (1) According to the ratio of potato starch and MCC to deionized water = 1:2, MCC was added to deionized water and stirred for 15 min under ultrasonic conditions at room temperature. Potato starch was added to the MCC suspension, and then a magnetic rotor was added and sealed. The mixture was stirred at 1000 rpm for 40 min on a magnetic stirring table to obtain a mixed solution. The mass ratio of potato starch to MCC was 70%:30%.

[0071] (2) Pour the mixture solution into a silicone mold (length*width*thickness = 8 cm*2 cm*0.2 cm), steam it in a steamer at 1200 W for 4 min, and cool it to room temperature to obtain starch-based hydrogel, denoted as PSM.

[0072] Rehydration properties of starch-based hydrogels prepared in Examples 1 and Comparative Examples 1-3:

[0073] Test method for rehydration properties: based on previous research methods. [2,8] The modified method was used to determine the rehydration properties of starch-based hydrogels. A 10 g sample of the starch-based hydrogel was weighed and then boiled in a beaker containing boiling water until no hard core remained inside; this was recorded as the optimal rehydration time. After removal, the sample was air-dried at room temperature for 30 seconds and weighed again (m1). The weight of the residue after drying the remaining boiling water in the beaker in an oven at 105 °C was recorded as m2. The rehydration properties were calculated using the following formula:

[0074] Rehydration rate (%) = m1 / 10 * 100;

[0075] Cooking loss rate (%) = m2 / 10*100;

[0076] Figure 2 Table 1 shows the rehydration times of starch-based hydrogels with PSN, PSCa, PSM, and different MCC ratios, respectively. Figure 2 A) Rehydration rate ( Figure 2 B) and cooking loss rate ( Figure 2 C) and the corresponding data. For example... Figure 2 As shown in Figure A, the rehydration time of the starch-based hydrogel gradually increased with the increase of MCC addition ratio (0%→50%). Compared with the control group, the rehydration time increased from 39.67 s (PSN), 42.36 s (PSM), and 45.50 s (PSCa) to 49.33-91.02 s (PSMCa-1~PSMCa-5). This phenomenon is attributed to the following: MCC, as an insoluble rigid filler phase, is uniformly dispersed within the starch gel network, playing a physical filling role. With the increase of MCC ratio, rigid microcrystals form a dense physical barrier, promoting a more compact gel network. Secondly, Ca... 2+The formation of calcium bridges through cross-linking with starch molecular chains and hydroxyl groups on the surface of MCC molecules creates a core-shell structure that further strengthens the gel network. This synergistic interaction reduces the diffusion path of water molecules in the starch-based hydrogel, slowing down the water molecule penetration rate and thus extending the rehydration time of the starch-based hydrogel.

[0077] like Figure 2 As shown in Figure B, compared with the control group, the rehydration rate of the starch-based hydrogel of the present invention decreased from 16.66% (PSN), 15.62% (PSM), and 14.87% (PSCa) to 14.45%-9.81% (PSMCa-1~PSMCa-5). This may be due to the Ca... 2+ High-density ionic crosslinking sites are formed between starch chains and at the starch-MCC interface, resulting in a high degree of physical entanglement and increased network crosslinking density. According to the polymer swelling theory, when the gel network absorbs water and swells, the molecular chain segments between the crosslinking points will generate elastic contraction forces; the greater the crosslinking density, the stronger the contraction force. Therefore, the rehydration rate of starch-based hydrogels continuously decreases with the increase of the MCC addition ratio.

[0078] like Figure 2 As shown in Figure C, compared with the control group, the cooking loss rate of the starch-based hydrogel of the present invention decreased from 2.71% (PSN), 2.46% (PSM), and 2.26% (PSCa) to 1.92%-0.62% (PSMCa-1~PSMCa-5). This is attributed to the excellent thermal stability and structural integrity of the starch-based hydrogel of the present invention. MCC, as a heat-resistant rigid fiber, constructs a stable physical support framework, physically restricting the migration of starch chains; simultaneously, Ca... 2+ Ionic cross-linking forms "calcium bridges," and the resulting "needle-piercing" effect "anchors" starch molecules to the MCC-reinforced phase, strongly locking in the dissolution of soluble starch components.

[0079] Table 1: Rehydration properties of starch-based hydrogels with different MCC contents

[0080]

[0081] The data in Table 1 are expressed as mean ± standard deviation (n = 3). The differences in the mean of different letters (ah) within the same column are statistically significant (p < 0.05).

[0082] Tensile and shear properties of starch-based hydrogels prepared in Examples 1 and Comparative Examples 1-3:

[0083] Methods for determining tensile and shear properties: based on previous research methods. [3,7]After reaching the optimal rehydration time, the tensile and shear properties of the samples were determined using a texture analyzer equipped with an HDP / LKBF probe and an A / TG tensile tool. Shear test parameters were set as follows: speed 2 mm / s before and after the test, speed 0.17 mm / s during the test, contact force 5 g, and deformation 80%. Tensile test parameters were set as follows: speed 3 mm / s before the test, speed 1 mm / s during the test, speed 3 mm / s after the test, contact force 5 g, and strain height 10 mm. Tensile strain (%), tensile stress (Pa), chewing hardness (g), texture hardness (g), and toughness (g / s) were calculated and recorded using the accompanying software. All sample tests were completed within 15 minutes of reaching the optimal rehydration time.

[0084] Figure 3 The tensile stress-strain curves of starch-based hydrogels with PSN, PSM, PSCa and different MCC ratios are shown. Figure 3 A) and shear curve ( Figure 3 B). From Figure 3 As can be seen from A, the tensile strain of PSN is 305.87% and the tensile stress is 1601 Pa; the tensile strain of PSCa is 221.93% and the tensile stress is 2345.12 Pa; and the tensile strain of PSM is 293.37% and the tensile stress is 1841.53 Pa. As the MCC content increased from 10% to 30%, the tensile strain of the starch-based hydrogels gradually increased, reaching 338.52%-450.31% (PSMCa-1~PSMCa-3), and the tensile stress also increased, reaching 1799.66-2163.78 Pa (PSMCa-1~PSMCa-3). Specifically, the tensile strain increased by 32.65%-144.44%, 116.59%-228.38%, and 45.15%-156.94% compared to PSN, PSCa, and PSM, respectively, while the tensile stress increased by 18.72%-37.03% compared to PSN. However, when the MCC content continued to increase to 40%-50%, the tensile strain of the hydrogels showed a significant decreasing trend. Compared to the control group, the tensile strain of PSMCa-4 and PSMCa-5 decreased to 96.14% and 52.64%, respectively.

[0085] from Figure 3As shown in Figure B, the shear forces of PSN, PSCa, and PSM were 10.45 g, 39.23 g, and 19.20 g, respectively. With the increase of the MCC addition ratio (10%-50%), the shear force of the starch-based hydrogel significantly increased to 24.36-35.26 g, showing a significant increasing trend, which was 2.33-3.37 times and 1.26-1.84 times higher than that of PSN and PSM, respectively. This phenomenon may be attributed to the following: when the MCC content is low (10%-30%), its particles can be uniformly dispersed in the starch gel matrix, acting as a rigid skeleton and physical cross-linking points. By binding with the hydroxyl groups of starch molecules, it effectively transfers stress and dissipates energy, thereby increasing tensile strain and stress intensity. However, when the MCC content is too high (40%-50%), its particles are unevenly dispersed in the gel matrix, and the particles are prone to agglomeration within the system, leading to uneven dispersion, weakened interfacial bonding, and phase separation, resulting in structural collapse and network breakdown. When external force is applied, due to the poor intermolecular bonding and excessive rigidity within the molecular chains, the balance between the rigid filler dispersion and interfacial interaction is broken, which in turn reduces the material's ductility and load-bearing capacity, thus simultaneously reducing tensile strain and stress. This transformation is essentially a process of MCC changing from an "effective reinforcing phase" to a "destructive defect."

[0086] Physical stability of the starch-based hydrogels prepared in Example 1 and Comparative Example 1:

[0087] Physical stability determination method: The physical stability of starch-based hydrogels was assessed by shrinkage and swelling rates, respectively, based on previous research methods. [3] With slight modifications, the shrinkage rate was tested as follows: A starch-based hydrogel sample was weighed and cut into pieces equal to 2 x 2 x 0.2 cm (length x width x height), and the initial volume S1 was calculated and recorded. The sample was then placed in a petri dish at room temperature and removed after 12, 24, 48, 72, and 96 hours, with the volume recorded as S2. The swelling rate was tested as follows: A suitable amount of starch-based hydrogel sample (10 g) was weighed and immersed in deionized water. At predetermined time intervals (12, 24, 48, 72, and 96 hours), the sample was removed, and the surface moisture was gently wiped away with filter paper. The mass after swelling was recorded as W1. The swelling and shrinkage rates were calculated using the following formulas:

[0088] Shrinkage rate (%) = (S1-S2) / S1*100;

[0089] Swelling rate (%) = (W1 - 10) / 10 * 100;

[0090] Figure 4 The physical stability of starch-based hydrogels at different time intervals was demonstrated, including swelling ratio ( Figure 4A) and shrinkage rate ( Figure 4 B). As shown in the figure, when the treatment time was 12 h, with the increase of the MCC addition ratio, the swelling rate decreased from 79.17% (PSN) to 31.86%-67.93% (PSMCa-1~PSMCa-5), and the shrinkage rate decreased from 24.49% (PSN) to 12.64%-19.83% (PSMCa-1~PSMCa-5). Compared with the control group (PSN), when the treatment time was extended from 12 h to 96 h, the swelling rate and shrinkage rate of the experimental group showed a significant decreasing trend. This phenomenon may be attributed to the fact that MCC and starch molecular chains are bonded by hydrogen bonds, and the network structure tends to be more compact, which not only limits the water absorption and swelling capacity of the molecular chains, but also anchors the molecular chains and inhibits the molecular chain rearrangement during long-term retrogradation. In addition, Ca 2+ The core-shell structure formed by the "bridging effect" further enhances the stability of the gel system, thereby delaying and reducing the overall swelling and shrinkage. This phenomenon is essentially the transformation of the flexible starch gel system into a composite gel system that combines rigidity and flexibility.

[0091] Antifreeze properties of starch-based hydrogels prepared in Examples 1 and 1-2:

[0092] Test method for antifreeze performance: based on previously reported methods. [4] With slight modifications, the antifreeze properties of starch-based hydrogels were determined using a differential scanning calorimeter (DSC-204F1). PSN, PSCa, and PSMCa-3 (5–10 mg) were placed in crucibles and sealed. The crucibles were then lowered from 25 °C to -180 °C at a rate of -5 °C / min, held at -180 °C for 5 min, and then raised to 25 °C at a rate of 5 °C / min. The temperatures at which the heat flux curves peaked during the heating process were recorded as the freezing points of all samples.

[0093] To further verify the performance effect of starch-based hydrogels at low temperatures, this invention conducted DSC tests on PSN, PSCa, and PSMCa-3. The actual photographs and DSC curves of their antifreeze performance tests are shown below. Figure 5 , 6 As shown. From Figure 6 The DSC curves show that the freezing point of PSN is -16.7 ℃, while the freezing points of PSCa obtained after calcium chloride soaking and PSMCa-3 obtained after adding MCC and soaking in calcium chloride are significantly reduced to -20.1 ℃ and -22.4 ℃, respectively, representing reductions of 3.4 ℃ and 5.7 ℃. These results indicate that Ca... 2+A significant effect in lowering the freezing temperature of starch-based gels was observed in the reduction of the freezeable free water content within the gel after immersion in calcium chloride solution. According to existing literature, the Ca in calcium chloride solution... 2+ It can dissociate and bind with 1-6 water molecules to form hydrated calcium ions with higher bond energy, which can significantly reduce the freezing temperature of liquid water in the gel. Therefore, as... Figure 5 As shown, due to Ca 2+ This antifreeze mechanism allows starch-based gels to maintain excellent mechanical properties (free curling) even at low temperatures of -20 ℃, providing strong theoretical support for their application under low-temperature conditions.

[0094] Moisturizing properties of the starch-based hydrogels prepared in Example 1 and Comparative Example 1:

[0095] Testing method for moisturizing performance: Based on previous research methods by Dong et al. [5] The moisturizing properties of starch-based hydrogels were determined. PSN and PSMCa-3 samples were placed in a constant temperature and humidity chamber under different temperature and humidity (RH) conditions (25 ℃, 50% RH; 36 ℃, 30% RH; 36 ℃, 80% RH; 65 ℃, 80% RH; 4 ℃, 50% RH; -18 ℃, 50% RH) for 12 h, with weight measured every 2 h. The water holding capacity was calculated using the following formula:

[0096] Water retention rate (%) = M1 / M0 * 100;

[0097] Where M0 represents the initial weight of the sample, and M1 represents the weight of the sample at different times.

[0098] Starch-based hydrogels are prone to embrittlement and hardening under dehydration conditions due to their moisture sensitivity, leading to a significant loss of their mechanical and adhesive properties. The moisturizing properties of PSN and PSMCa-3 under different temperature and RH conditions are shown below. Figure 7 As shown. Figure 7 A shows that in a simulated indoor environment (25 ℃, 50% RH), PSN experienced severe moisture loss (≈58%) within 12 hours; in contrast, PSMCa-3 maintained a water retention rate of up to 72.84% within the same time period.

[0099] Given the potential sensitivity of the moisturizing properties of starch-based hydrogels to temperature and humidity, this invention further tested the water retention rates of PSN and PSMCa-3 under a drying environment of 36 ℃ and 30% RH. The results are as follows: Figure 7As shown in Figure B, the water retention rate of PSN dropped sharply to 41.39% after 12 hours, while the water retention rate of PSMCa-3 remained at 61.59%, which is significantly higher than that of the all-natural adhesive PSN.

[0100] Subsequently, the test was extended to high humidity conditions of 36°C and 80% RH, and the results were as follows: Figure 7 As shown in Figure C, the water retention rate of PSMCa-3 is as high as 81.69%, which is 1.51 times that of PSN (54.03%). Figure 7 As shown in Figure D, under high temperature and high humidity conditions (65℃, 80% RH), the water retention rate of PSN was only 41.98% after 12 hours, while the water retention rate of PSMCa-3 remained at a high level of 79.71%, which is 1.89 times that of PSN.

[0101] In addition, the water retention rates of PSN and PSMCa-3 under low-temperature conditions were also tested, and the results are as follows: Figure 7 As shown in E and 7F, PSMCa-3 can still maintain a high moisture content of over 70% under low temperature conditions.

[0102] The above results fully demonstrate that the starch-based hydrogel prepared by the method of the present invention exhibits high moisturizing properties under different environmental conditions. This phenomenon may be attributed to the fact that MCC acts as a rigid framework in the starch-based gel matrix, tightly binding with starch molecules through hydrogen bonds, forming a denser and mechanically stronger three-dimensional network structure. 2+ Ionic crosslinking occurs with the hydroxyl groups on the surface of starch and cellulose, forming a core-shell structure that enhances the stability of the entire gel network. Furthermore, Ca... 2+ By forming coordination bonds with water molecules in starch-based gels, hydrated ion clusters are constructed, effectively inhibiting the free movement of water molecules and reducing water loss. This synergistic effect of "physical enhancement" and "ionic cross-linking" makes the gel's network structure more robust, which can more effectively bind and lock in water molecules, thereby significantly improving its water retention capacity.

[0103] Adhesive properties of the starch-based hydrogel prepared in Example 1:

[0104] Adhesion performance testing method: based on previous research methods [6] The PSMCa-3 samples were cut into a fixed shape (length * width * height = 20 * 20 * 2 mm), and then adhesion tests were performed on different soft and hard substrates.

[0105] Figure 8The adhesion properties of PSMCa-3 on different substrates are shown in the figure. PSMCa-3 exhibits significant adhesion to various soft and hard substrates, including foam, plastic, steel, paper, wood, rubber, leaf, and glass.

[0106] like Figure 9 As shown, PSMCa-3 exhibits extremely strong adhesive force, capable of lifting objects weighing 4000-6000 times its own weight, and maintaining strong adhesion even after being soaked in water for 2 hours and subjected to 20 repeated lifting cycles.

[0107] In addition, such as Figure 10 As shown, PSMCa-3 can adhere tightly to the surfaces of joints such as the wrist, finger, elbow, and knee, allowing for free bending without detachment; Figure 11 As shown, PSMCa-3 adhered to the skin surface multiple times without leaving any residue. This phenomenon may be attributed to the -OH group providing a basis for adhesion, and the Ca... 2+ The starch-based hydrogel undergoes strong coordination crosslinking with -OH groups, which significantly enhances the cohesive strength of the starch-based gel network. When the starch-based hydrogel of this invention comes into contact with substrates such as skin, its abundant hydroxyl and calcium ions on the surface can rapidly form hydrogen bonds, ionic bonds, and coordination bonds with various functional groups such as amino, carboxyl, and hydroxyl groups on the substrate surface, resulting in strong interfacial adhesion. This dynamic balance between internal coordination crosslinking (strong cohesion) and interfacial multi-element bonding (strong adhesion) allows it to adhere firmly to various surfaces and leaves no residue upon peeling due to the reversibility of the bonding.

[0108] Wood bonding strength of the starch-based hydrogel prepared in Example 1:

[0109] The bonding strength of adhesives to wood depends on their ability to effectively transfer and dissipate stress at the fiber interface, which also supports the durability of plywood structures. To further quantitatively evaluate the bonding strength of this invention in wood applications, a standardized shear test procedure is established, as follows:

[0110] Based on previous research methods [1]Slight modifications were made. An appropriate amount of starch-based hydrogel was taken, and after shearing (100 rpm, 10 min), it was evenly applied to the surface of the wood (length × width = 15*15 mm) according to the set coating amount. Then, a hot-pressing process was performed. The hot press (HP-100) was preheated to 100℃ for 5 min, and then the wood was placed on the hot-press interface. Treatment was carried out according to different temperatures, times, and pressures. After hot-pressing, the wood panels were left to stand at 25℃ and 30% RH for 6 h, and then transferred to 25℃ and 50% RH storage for subsequent experimental measurements.

[0111] like Figure 12 As shown in A, with 50-250 g / m 2 The coating was evenly applied to the interface between the two pieces of wood, and the bond strength was systematically evaluated under the same treatment conditions. The bond strength evaluation results are as follows: Figure 12 As shown in Figure B, when the hot-pressing temperature is 140 ℃, the pressure is 1-1.2 MPa, and the time is 30 min, as the coating amount increases from 50 g / m²... 2 Increased to 250 g / m 2 The adhesive strength of PSMCa-3 shows a trend of first increasing and then decreasing, ranging from 50-200 g / m². 2 Within the coating amount range, the adhesive strength increases sharply, which is due to insufficient crosslinking strength and incomplete interface coverage provided by low coating amounts; at a coating amount of 200 g / m 2 At this point, PSMCa-3 fully fills the interfacial pores and forms a good adhesive network, achieving peak bond strength. However, when the coating amount is further increased to 250 g / m², the bond strength decreases. 2 However, excessive coating does not further improve adhesion performance; instead, it reduces bonding strength. This may be because excessive coating leads to a thick adhesive layer at the wood interface, resulting in severe interfacial stress concentration. Some MCC particles become over-enriched or agglomerated at the interface, forming micropores or weak boundary layers, causing uneven or separated reinforcing phases, thus weakening the interfacial bonding strength. These results confirm that the adhesive strength of starch-based hydrogels is strongly dependent on the coating amount. For PSMCa-3, under a hot-pressing process at 140 ℃, 30 min, and 1-1.2 MPa, a coating strength of 200 g / m³ is significantly reduced. 2 The optimal coating amount.

[0112] Hot pressing parameters also have a crucial impact on crosslinking and interfacial anchoring, such as Figure 12 As shown in Figure C, the coating amount of PSMCa-3 is fixed at 200 g / m². 2The optimal balance was achieved under hot-pressing conditions of 140 ℃, 30 min, and 1–1.2 MPa, resulting in a high bond strength of 10.228 MPa, while simultaneously promoting molecular mobility and chemical bonding. Insufficient curing (120 ℃, 10 min) led to weaker bonding (3.302 MPa) due to incomplete penetration and limited cross-linking. Excessive hot-pressing (180 ℃, 90 min) caused the substrate to become brittle and significantly reduced the bond strength (1.135 MPa). These results can be attributed to significant interfacial fusion and structural reconstruction between adjacent cell walls within the wood during hot-pressing. Physically, the interpenetration of adjacent cell walls forms a mechanically interlocking structure, effectively enhancing interfacial load transfer and energy dissipation. Chemically, etherification reactions occurred between starch and MCC molecules and the hydroxyl groups of lignin and carbohydrates, generating a robust chemical anchoring network. The synergistic effect of these two factors makes the cured bond interface indistinguishable from the entire wood matrix, indicating deep molecular penetration, plasticization, and covalent bonding between cell walls. In summary, the above results demonstrate that the superior adhesive properties of the starch-based hydrogel of this invention stem from deep penetration, dense interfacial structure, thermally activated ether crosslinking, and a mechanically robust network capable of transferring stress beyond the substrate strength. By combining hot-pressing conditions and optimizing parameter ratios to ensure thorough crosslinking and effective penetration, structural and chemical coupling is achieved, resulting in excellent strength and durability under various environmental conditions.

[0113] Furthermore, the present invention is applicable under optimal adhesion conditions (coating amount 200 g / m²). 2 The practical reliability of the wood bonding strength (temperature 140 ℃, time 30 min, pressure 1-1.2 MPa) was demonstrated by tensile testing of the wood boards in both vertical and horizontal directions. The bonded wood was able to withstand the weight of an 80 kg adult. Figure 13 A) and the horizontal pull of 10 adults ( Figure 13 B). This invention also demonstrates, using a covalent matrix-interface bonding strategy, that the adhesive system achieves excellent adhesion performance under various conditions, such as... Figure 14 As shown, after exposing the bonded wood to extreme temperatures of -198, -18, 80, and 150 °C for 12 h, the corresponding bond strengths remained at 3.57, 4.81, 7.28, and 6.683 MPa, respectively, all exceeding the commercial threshold of 0.7 MPa (the bond strength of commercially available adhesive products). These test results highlight the universal applicability and structural robustness of the starch-based hydrogel of this invention.

[0114] Example 2: Effects of calcium chloride solution concentration and soaking time on the tensile properties of starch-based hydrogels

[0115] The preparation steps of the starch-based hydrogel in this embodiment are as follows:

[0116] (1) Preparation of starch solution: Weigh an appropriate amount of potato starch and mix it evenly according to the ratio of starch: water = 1:2.

[0117] (2) Gelatinization: Pour the starch solution into a silicone mold (length*width*thickness = 8 cm*2 cm*0.2 cm), steam it in a steamer at 1200 W for 4 min, and cool it to room temperature.

[0118] (3) Crosslinking: After cooling, the material was immersed in calcium chloride solutions (1M, 3M, 5M) for 10 min, 40 min, and 100 min, respectively, to obtain starch-based hydrogels. The residual calcium chloride solution on the surface of the composite hydrogels was wiped off with a lint-free cloth and labeled as PSCa. 1-10 (1M, 10 min), PSCa 1-40 (1M, 40 min), PSCa 1-100 (1M, 100 min), PSCa 3-10 (3M, 10 min), PSCa 3-40 (3M, 40 min), PSCa 3-100 (3M, 100 min), PSCa 5-10 (5M, 10 min), PSCa 5-40 (5M, 40 min).

[0119] Figure 15 The effects of calcium chloride solutions of different concentrations (1M, 3M, 5M) on the tensile properties of starch-based hydrogels under different soaking times (10 min, 40 min, 100 min) are shown in detail. Figure 15 A represents the stress-strain curves of starch-based hydrogels prepared by soaking in a 1M calcium chloride solution for different times. The graph shows that at the low concentration of 1M, the tensile strain and strain of the starch-based hydrogel initially increase and then decrease with prolonged soaking time. The best tensile properties are observed after 40 minutes of soaking, with stress and strain reaching 2198 Pa and 194.43%, respectively. However, when the soaking time is further extended to 100 minutes, both tensile strain and stress decrease significantly. This is likely because prolonged soaking in a low-concentration calcium chloride solution leads to swelling due to the low-salt environment. During this process, more water molecules penetrate into the gel, causing some damage to the gel network structure and consequently reducing the gel's mechanical properties, specifically manifested as a decrease in tensile strain and tensile stress.

[0120] Figure 15B is the stress-strain curve of starch-based hydrogels prepared by soaking for different times when the calcium chloride solution concentration is 3M. ​​It can be seen from the figure that the tensile properties of the starch-based hydrogel are the best when soaked for 40 min at the 3M concentration, with tensile strain and stress of 221.93% and 2345.12 Pa, respectively. This indicates that the network structure of the starch-based hydrogel is relatively stable under this condition.

[0121] Figure 15 C represents the stress-strain curves of starch-based hydrogels prepared by soaking in a 5M calcium chloride solution for different times. The graph shows that in a high-concentration calcium chloride solution, soaking for a shorter time (10-40 min) slightly increases the tensile stress of the starch-based hydrogel. However, when the time is further extended to 100 min, the hydrogel becomes highly dehydrated and plastic-like, making it impossible to effectively measure the stress-strain curve; therefore, this data was not included in the analysis. This phenomenon may be attributed to the fact that in a high-salt environment, the gel dehydration process intensifies the density and interchain friction of the starch molecular chains, making it difficult for the molecular chains to stretch and slide, thus significantly increasing the tensile stress of the starch-based hydrogel and reducing its elongation. Based on the above experimental results, it can be found that the starch-based hydrogel exhibits the best tensile properties when the calcium chloride concentration is 3M and the soaking time is 40 min.

[0122] Example 3: Universality Verification: The Effect of the Invention Strategy on the Tensile Properties of Different Starch Types

[0123] The preparation steps of the starch-based hydrogel in this embodiment are as follows:

[0124] (1) Preparation of MCC suspension: Weigh MCC, add deionized water in a ratio of 1:2 (total mass of MCC and starch: deionized water), stir vigorously for 15 min under ultrasonic conditions at room temperature to prevent MCC from agglomerating, and obtain MCC suspension.

[0125] (2) Preparation of the mixture solution: Pea starch, mung bean starch, corn starch, wheat starch, sweet potato starch and cassava starch were added to the MCC suspension respectively, stirred for 5 min under ultrasonic conditions at room temperature, and then a magnetic rotor was added and sealed. The mixture was stirred on a magnetic stirring table at 1000 rpm for 40 min to obtain the mixture solution; the mass ratio of starch to MCC was 70%:30%.

[0126] (3) Gelatinization: Pour the mixture solution into a silicone mold (length*width*thickness = 8 cm*2 cm*0.2 cm), steam it in a steamer at 1200 W for 4 min, and cool it to room temperature.

[0127] (4) Crosslinking: After cooling, the material was immersed in a 3M calcium chloride solution for 40 min to obtain a starch-based hydrogel. The residual calcium chloride solution on the surface of the composite hydrogel was wiped off with a lint-free cloth to obtain the starch-based hydrogel, which was denoted as Peagel@MCC. 30 munggel@MCC 30 corngel@MCC 30 wheatgel@MCC 30 sweetpotatogel@MCC 30 cassavagel@MCC 30 .

[0128] Mechanical properties of the starch-based hydrogel prepared in Example 3:

[0129] To verify the universality of the preparation method of this invention in improving the mechanical properties of starch-based hydrogels, this invention further investigated the effect of this process on the mechanical properties of different types of starch-based gels, and the results are as follows: Figure 16 As shown. Figure 16 A shows that the tensile stress of the control group pea starch-based hydrogel (Peagel-control) (prepared according to Comparative Example 1) was 6111.50 Pa, and the tensile strain was 115.73%; while the Peagel@MCC of the present invention... 30 It exhibited significant improvements in mechanical properties, with tensile stress increasing dramatically to 7076.30 Pa and tensile strain also significantly increasing to 177.03%, representing increases of 964.80 Pa and 61.3% respectively compared to the control group. This indicates that the addition of MCC and calcium ion treatment significantly improved the mechanical properties of the pea starch-based adhesive. Furthermore, through comprehensive analysis... Figure 16 BF. A general conclusion can be drawn: the preparation strategy of this invention is not only effective for potato starch-based adhesives, but also significantly improves the mechanical properties of pea starch-based adhesives, mung bean starch-based adhesives, corn starch-based adhesives, wheat starch-based adhesives, sweet potato starch-based adhesives, and cassava starch-based adhesives. These results further confirm the broad applicability and significant effect of the preparation strategy proposed in this invention in improving the mechanical properties of starch-based adhesives. This is of great significance for broadening the application of starch-based adhesives in the food, pharmaceutical, and other fields, and provides new ideas and methods for subsequent research.

[0130] In summary, this invention obtains a starch-based hydrogel by uniformly mixing starch and MCC, gelatinizing the mixture, and then soaking it in a calcium chloride solution. The starch-based hydrogel exhibits excellent adhesive properties and maintains good bonding strength even under extreme environments, showing broad application prospects. Furthermore, the preparation process of this invention is simple, efficient, environmentally friendly, and safe, requiring no high-temperature, prolonged heating, pH adjustment, or additional chemical crosslinking agents, thus meeting the industrial-scale, high-efficiency production needs of wood bonding.

[0131] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0132] References:

[0133] [1] FY Tang, JS Qiu, XX Wu, YF Liu, QD Hu, CC, Cai, JA Zhang&X. S. Li. Strong and Weather-Resistant Wood Bonding Enabled by CellWall–Inspired Ether-Anchored Lignin. Adv. Funct. Mater https: / / doi.org / 10.1002 / adfm.202527965.

[0134] [2] RYZhang, MH Guan, ZH Wang, M. Li&Q.J.Sun. Calcium ion-enhanced physically double-crosslinked starch-sodium alginate hydrogels: Asustainable approach for improving the quality of thermally sterilized ricenoodles. International Journal of Biological Macromolecules. , 319 (3), Article145568, https: / / doi.org / 10.1016 / j.ijbiomac.2025.145568.

[0135] [3] R.Y.Zhang, Z.X. Wang, X. Y. He, Z.H. Xu, M. Li&Q.J.Sun. Effectsof sweet potato starch on the physicochemical properties and edible qualitiesof instant fresh rice noodles. International Journal of BiologicalMacromolecules. 286, Article 138553.

[0136] [4] S.J. Wu, Z. Liu, C.H. Gong, W.J. Li, S.J. Xu, R. Wen, W. Feng,Z.M. Qiu&Y.R.Yan. Spider-silk-inspired strong and tough hydrogel fibers withanti-freezing and water retention properties. Nature Communications. 4441 (2024) .

[0137] [5] Lilong Cao, Zhijie Zhao, Junjie Li, Yunfeng Yi, Yuping Wei. Gelatin-Reinforced Zwitterionic Organohydrogel with Tough, Self-Adhesive, Long-Term Moisturizing and Antifreezing Properties for Wearable Electronics. Biomacromolecules. 23 / 3 .

[0138] [6] J.L. Zou, Z.W. Lin, L.J. Zhan, Y. Qin, Q.J. Sun, N. Ji&F.W. Xie.A short linear glucan nanocomposite hydrogel formed by in situ self-assemblywith highly elastic, fatigue-resistant and self-recovery. Food Hydrocoll ., 340(2024), Article 122241, 10.1016 / j.carbpol.2024.122241.

[0139] [7] Gao, L., Guan, M., Qin, Y., Ji, N., Wang, Y., Li, Y., Li, M.,Xiong, L.,&Sun, Q. Utilization of heat-induced curdlan gel to improve thecooking qualities of thermally sterilized fresh rice noodles, International Journal of Biological Macromolecules . 262 (Part 1) (2024) 129693, https: / / doi.org / 10.1016 / j.ijbiomac.2024.129693.

[0140] [8] Gao, L., Xu, Z., Zhang, R., Qin, Y., Ji, N., Wang, Y., Xiong,L.,&Sun, Q, Effects of erythritol on rheological properties of rice flour andstructural characteristics of extruded dried rice noodles with rapidrehydration behaviors, Food Hydrocoll. 144 (2023) 109007, https: / / doi.org / 10.1016 / j.foodhyd.2023.109007.

Claims

1. A method for preparing a starch-based hydrogel with high mechanical properties, characterized in that, Includes the following steps: Starch is added to a microcrystalline cellulose suspension and mixed evenly to obtain a mixture solution; the mass ratio of starch to microcrystalline cellulose is (90%-50%):(10%-50%); the mixture solution is gelatinized, cooled, and then soaked in a calcium chloride solution to obtain a starch-based hydrogel with high mechanical properties.

2. The method for preparing a starch-based hydrogel with high mechanical properties according to claim 1, characterized in that, The concentration of the calcium chloride solution is 1-5 mol / L.

3. The method for preparing a starch-based hydrogel with high mechanical properties according to claim 2, characterized in that, The soaking time is 10-100 min.

4. The method for preparing a starch-based hydrogel with high mechanical properties according to claim 1 is characterized in that, After adding starch to the microcrystalline cellulose suspension, stir under ultrasonic conditions at room temperature for 1-10 min, and then stir on a magnetic stirring table at a speed of 800-1200 rpm for 10-60 min to ensure thorough mixing and obtain a mixture solution.

5. The method for preparing a starch-based hydrogel with high mechanical properties according to claim 4, characterized in that, The specific preparation process of the microcrystalline cellulose suspension is as follows: add microcrystalline cellulose to deionized water, and stir vigorously for 5-30 minutes under ultrasonic conditions at room temperature to prevent the microcrystalline cellulose molecules from agglomerating, thereby obtaining the microcrystalline cellulose suspension.

6. The method for preparing a starch-based hydrogel with high mechanical properties according to claim 1 is characterized in that, The gelatinization process is as follows: pour the mixture solution into a silicone mold and steam it in a steamer at a power of 900-1200 W for 4-5 minutes.

7. A starch-based hydrogel with high mechanical properties prepared by the preparation method according to any one of claims 1-6.

8. The method of applying the high mechanical property starch-based hydrogel according to claim 7, characterized in that, include: The high mechanical properties starch-based hydrogel described in claim 7 is sheared and then coated onto the interface of the substrate to be bonded, followed by hot pressing to achieve material bonding.

9. The method for applying the high mechanical property starch-based hydrogel according to claim 8, characterized in that, The coating amount of the high mechanical property starch-based hydrogel is 50-250 g / m³. 2 .

10. The method of applying the high mechanical property starch-based hydrogel according to claim 8, characterized in that, The process parameters for the hot pressing treatment are: temperature: 120-180 ℃, time: 10-90 min, pressure: 1-1.2 MPa.

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