Degradable film and preparation method thereof

Abstract

According to the degradable film and the preparation method thereof, konjaku flour, vegetable protein, amylose corn starch, cyclodextrin and deionized water are used as raw materials, reagents such as a sodium periodate solution and an ethylene glycol solution participate in a reaction, and the konjaku flour and the vegetable protein are covalently grafted to prepare the degradable film. And by utilizing a linear crystal structure of the amylose corn starch and a cavity inclusion effect of cyclodextrin and utilizing a cross-linked structure of a three-dimensional network formed by starch gelatinization and protein, casting, drying and uncovering the film to obtain the degradable film. The problems that an existing degradable film prepared by taking konjaku flour as a base material is weak in mechanical property and poor in practicability are solved, the comprehensive performance of the degradable film is improved, and the degradable film has good mechanical property, barrier property and flexibility and is suitable for food packaging, agricultural plastic mulching films, medical dressings and other scenes.

Description

Technical Field

[0001] This invention relates to the field of biodegradable membrane materials technology, and in particular to a biodegradable membrane and a method for preparing the biodegradable membrane. Background Technology

[0002] The "white pollution" problem caused by traditional petroleum-based plastic films (such as PE and PP) due to their difficulty in degradation and long-term residue has become a key focus of ecological and environmental governance. Against this backdrop, biodegradable film materials (such as PLA, PBAT, and starch-based composites) have attracted widespread attention as alternatives. While current mainstream products possess biodegradability, they still suffer from the following drawbacks: First, their mechanical properties (such as tensile strength and puncture resistance) are significantly inferior to traditional films, especially in humid environments where they are prone to softening and failure; second, their high cost limits large-scale application; and third, insufficient adaptability to processing technologies, with some materials requiring specialized equipment or complex modification processes, hindering industrialization and promotion.

[0003] Addressing the issues of traditional petroleum-based plastic films being "difficult to degrade and heavily polluting," and existing biodegradable films being costly and lacking in performance, the technology of preparing biodegradable film materials using konjac flour and other polysaccharides as the core substrate has achieved widespread application. The main component of konjac flour is konjac glucomannan (KGM), a water-soluble, biodegradable high-molecular-weight polysaccharide extracted from konjac corms. It possesses excellent gelling, thickening, and film-forming properties, and is widely used in the food industry as a film-forming material. However, existing biodegradable films prepared using konjac flour as a substrate are limited to a simple process of dissolution-casting-drying. The resulting products have weaker mechanical properties than traditional film materials and suffer from defects such as easy swelling upon contact with water, resulting in poor practicality. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a biodegradable membrane and a method for preparing the biodegradable membrane, which solves the problems of weak mechanical properties and poor practicality of biodegradable membranes prepared with konjac flour as a substrate in the prior art.

[0005] According to an embodiment of the present invention, a biodegradable membrane comprises, by weight parts: 1.0 part konjac powder, 1.5-1.8 times the weight of konjac powder of plant protein, 3.5-4.5 times the weight of konjac powder of linear corn starch, 15.0%-20.0% of the weight of konjac powder of cyclodextrin, and 100.0-120.0 times the weight of konjac powder of deionized water.

[0006] On the other hand, according to embodiments of the present invention, a method for preparing a biodegradable membrane is also provided, comprising the following steps: S1. Add konjac powder to deionized water and stir to disperse the konjac powder in the deionized water to obtain solution A; S2. Add sodium periodate solution to solution A obtained in step S1, heat and stir to obtain solution B; S3. Add ethylene glycol solution to solution B obtained in step S2 and continue stirring to obtain solution C; S4. Add plant protein to solution C obtained in step S3, heat and stir to obtain solution D; S5. Centrifuge the solution D obtained in step S4 to remove residual suspended matter and collect precipitate E; S6. Add linear corn starch, cyclodextrin and precipitate E obtained in step S5 to deionized water, adjust the pH of the system to form a mixture F, and place the mixture F in a constant temperature water bath for ultrasonic treatment. S7. Heat and stir the ultrasonically treated mixture F from step S6. Continuously monitor the viscosity of mixture F during stirring until the starch in mixture F is fully gelatinized and not caramelized. S8. Cast the gelatinized mixture F from step S7 onto a clean glass plate to obtain a membrane. After casting, dry the membrane. After drying, peel off the membrane and cool it at room temperature to obtain a biodegradable membrane.

[0007] Compared with the prior art, the present invention has the following beneficial effects: 1. The biodegradable membrane prepared by this invention uses konjac flour as the core raw material, combined with natural polymers such as plant protein and linear corn starch. All of these are derived from natural plants, are completely biodegradable, and have no petroleum-based components added during the preparation process. The biodegradable membrane prepared will not cause secondary pollution and is environmentally friendly. 2. The biodegradable membrane prepared by this invention utilizes the covalent grafting of konjac flour and plant protein to improve the flexibility and puncture resistance of the membrane material. It also utilizes the linear crystalline structure of linear corn starch and the cavity inclusion effect of cyclodextrin to synergistically improve the barrier properties of the membrane material. At the same time, it utilizes the three-dimensional network formed by starch gelatinization and the cross-linking structure of proteins to improve the temperature resistance of the membrane material. In other words, the comprehensive performance of the biodegradable membrane is improved through oxidative grafting and multi-component compounding, giving it good mechanical properties, temperature resistance, barrier properties and flexibility, making it suitable for food packaging, agricultural mulch film, medical dressings and other applications.

[0008] 3. The preparation method used in this invention is compatible with traditional plastic processing equipment (such as casting machines, blown film machines, etc.), and can be industrialized without additional modifications, reducing equipment investment costs. Furthermore, the use of deionized water as a solvent in the preparation process avoids pollution caused by the use of organic solvents and meets the safety requirements for food contact materials. Attached Figure Description

[0009] Figure 1 This is a step diagram of the biodegradable membrane preparation method according to an embodiment of the present invention. Detailed Implementation

[0010] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0011] Example 1 like Figure 1 As shown, Embodiment 1 of the present invention proposes a method for preparing a biodegradable membrane, comprising the following steps: S0. Weigh the following raw materials by weight: 1.0 part konjac powder, 1.5 times the weight of plant protein of konjac powder, 4.0 times the weight of linear corn starch of konjac powder, 15.0% of the weight of cyclodextrin of konjac powder, and 100.0 times the weight of deionized water of konjac powder.

[0012] S1. Add 1 part of konjac powder to 75.0 times its weight of deionized water and stir at 200.0 r / min for 10.0 min to disperse and obtain solution A.

[0013] S2. Add a 0.5 mol / L sodium periodate solution (1.1 times the mass of konjac powder) to solution A obtained in step S1, heat to 80.0℃ and stir at 300.0 r / min for 4.5 min to obtain solution B.

[0014] In step S2, konjac flour is grafted onto plant protein by adding sodium periodate solution for oxidative grafting.

[0015] S3. Add 1.2 times the mass of sodium periodate solution to solution B obtained in step S2, and continue stirring for 15.0 min to obtain solution C.

[0016] In step S3, adding an excess of ethylene glycol solution avoids excessive reaction of sodium periodate and also acts as a plasticizer.

[0017] S4. Add 1.5 times the mass of konjac powder to the solution C obtained in step S3 and heat to 81.0℃. Stir at 5000.0 r / min for 1.5 min to obtain solution D.

[0018] S5. Centrifuge the solution D obtained in step S4 at 8000.0 rpm for 10.0 min to remove residual suspended matter and collect precipitate E.

[0019] S6. Add 4.0 times the mass of konjac powder of linear corn starch, 15.0% of the mass of konjac powder of cyclodextrin, and the precipitate E obtained in step S5 to the remaining deionized water (25.0 times the mass of konjac powder). Adjust the pH of the system to 6.4-6.6 to form a mixture F. Place the mixture F in a constant temperature water bath at 73.0℃ and sonicate it at a frequency of 40.0kHz for 17.0min.

[0020] S7. Heat the ultrasonically treated mixture F from step S6 to 85.0℃ and stir for 11.0 min. During the stirring process, continuously monitor the viscosity of mixture F until the starch in mixture F is fully gelatinized and not caramelized.

[0021] S8. The gelatinized mixture F from step S7 is cast onto a clean glass plate using a scraper to obtain a film. The cast film is placed in a forced-air drying oven and dried at 56.0℃ for 18.0h. During the drying process, the surface of the film is checked regularly for cracks and bubbles, and the moisture content of the film is monitored using a rapid moisture analyzer to ensure it meets the standard. After drying, the film is peeled off and cooled at room temperature for 36.0h to eliminate internal stress, thus obtaining a biodegradable film.

[0022] Example 2 like Figure 1 As shown in Embodiment 2 of the present invention, a method for preparing a biodegradable membrane is proposed, comprising the following steps: S0. Weigh the following raw materials by mass: 1.0 part of konjac powder, 1.6 times the mass of plant protein of konjac powder, 3.5 times the mass of linear corn starch of konjac powder, 17.5% of the mass of cyclodextrin of konjac powder, and 110.0 times the mass of deionized water of konjac powder.

[0023] S1. Add 1 part of konjac powder to 70 times its weight of deionized water and stir at 200.0 r / min for 10.0 min to disperse and obtain solution A.

[0024] S2. Add a 0.5 mol / L sodium periodate solution (1.2 times the mass of konjac powder) to solution A obtained in step S1, heat to 80.0℃ and stir at 300.0 r / min for 4.5 min to obtain solution B.

[0025] S3. Add 1.3 times the mass of sodium periodate solution to solution B obtained in step S2, and continue stirring for 12.0 min to obtain solution C.

[0026] S4. Add 1.6 times the mass of konjac powder to the solution C obtained in step S3 and heat to 81°C. Stir at 5500.0 r / min for 1.7 min to obtain solution D.

[0027] S5. Centrifuge the solution D obtained in step S4 at 9000.0 rpm for 12.0 min to remove residual suspended matter and collect precipitate E.

[0028] S6. Add 3.5 times the mass of konjac powder, 17.5% of the mass of konjac powder, cyclodextrin, and the precipitate E obtained in step S5 to the remaining deionized water (40.0 times the mass of konjac powder). Adjust the pH of the system to 6.4-6.6 to form a mixture F. Place the mixture F in a constant temperature water bath at 70.0℃ and sonicate it at a frequency of 40.0kHz for 17.0min.

[0029] S7. Heat the ultrasonically treated mixture F from step S6 to 84.0℃ and stir for 10.0 min. During the stirring process, continuously monitor the viscosity of mixture F until the starch in mixture F is fully gelatinized and not caramelized.

[0030] S8. The gelatinized mixture F from step S7 is cast onto a clean glass plate using a scraper to obtain a film. The cast film is placed in a forced-air drying oven and dried at 56.0℃ for 18.0h. During the drying process, the surface of the film is checked regularly for cracks and bubbles, and the moisture content of the film is monitored using a rapid moisture analyzer to ensure it meets the standard. After drying, the film is peeled off and cooled at room temperature for 30.0h to eliminate internal stress, thus obtaining a biodegradable film.

[0031] Example 3 like Figure 1 As shown, Embodiment 3 of the present invention proposes a method for preparing a biodegradable membrane, comprising the following steps: S0. Weigh the following raw materials by weight: 1.0 part konjac powder, 1.8 times the weight of plant protein of konjac powder, 4.5 times the weight of linear corn starch of konjac powder, 20.0% of the weight of cyclodextrin of konjac powder, and 120.0 times the weight of deionized water of konjac powder.

[0032] S1. Add 1 part of konjac powder to 75.0 times its weight of deionized water and stir at 200.0 r / min for 10.0 min to disperse and obtain solution A.

[0033] S2. Add a 0.5 mol / L sodium periodate solution (1 times the mass of konjac flour) to solution A obtained in step S1, heat to 80.0℃ and stir at 300.0 r / min for 4.5 min to obtain solution B.

[0034] S3. Add 1.4 times the mass of sodium periodate solution to solution B obtained in step S2, and continue stirring for 10.0 min to obtain solution C.

[0035] S4. Add 1.8 times the mass of konjac flour to the solution C obtained in step S3 and heat to 81°C. Stir at 6000.0 r / min for 1.6 min to obtain solution D.

[0036] S5. Centrifuge the solution D obtained in step S4 at 10000.0 rpm for 13.0 min to remove residual suspended matter and collect precipitate E.

[0037] S6. Add 4.5 times the mass of konjac powder of linear corn starch, 20.0% of the mass of konjac powder of cyclodextrin, and the precipitate E obtained in step S5 to the remaining deionized water (45.0 times the mass of konjac powder). Adjust the pH of the system to 6.4-6.6 to form a mixture F. Place the mixture F in a constant temperature water bath at 71.0℃ and sonicate it at a frequency of 40.0kHz for 17.0min.

[0038] S7. Heat the ultrasonically treated mixture F from step S6 to 84.5℃ and stir for 13.0 min. During the stirring process, continuously monitor the viscosity of mixture F until the starch in mixture F is fully gelatinized and not caramelized.

[0039] S8. The gelatinized mixture F from step S7 is cast onto a clean glass plate using a scraper to obtain a film. The cast film is placed in a forced-air drying oven and dried at 56.0℃ for 18.0h. During the drying process, the surface of the film is checked regularly for cracks and bubbles, and the moisture content of the film is monitored using a rapid moisture analyzer to ensure it meets the standard. After drying, the film is peeled off and cooled at room temperature for 24.0h to eliminate internal stress, thus obtaining a biodegradable film.

[0040] Example 4 like Figure 1 As shown, Embodiment 4 of the present invention proposes a method for preparing a biodegradable membrane, comprising the following steps: S0. Weigh the following raw materials by mass: 1.0 part of konjac powder, 1.7 times the mass of plant protein of konjac powder, 4.0 times the mass of linear corn starch of konjac powder, 15.0% of the mass of cyclodextrin of konjac powder, and 115.0 times the mass of deionized water of konjac powder.

[0041] S1. Add 1 part of konjac powder to 70.0 times its weight of deionized water and stir at 200.0 r / min for 10.0 min to disperse and obtain solution A.

[0042] S2. Add a 0.5 mol / L sodium periodate solution (1.3 times the mass of konjac flour) to solution A obtained in step S1, heat to 80.0℃ and stir at 300.0 r / min for 4.5 min to obtain solution B.

[0043] S3. Add 1.2 times the mass of sodium periodate solution to solution B obtained in step S2, and continue stirring for 14.0 min to obtain solution C.

[0044] S4. Add 1.7 times the mass of konjac flour to the solution C obtained in step S3 and heat to 81°C. Stir at 5750.0 r / min for 1.8 min to obtain solution D.

[0045] S5. Centrifuge the solution D obtained in step S4 at 8500.0 rpm for 11.0 min to remove residual suspended matter and collect precipitate E.

[0046] S6. Add 4.0 times the mass of konjac powder, 15.0% of the mass of konjac powder, 15.0% of the mass of konjac powder, and the precipitate E obtained in step S5 to the remaining deionized water (45.0 times the mass of konjac powder). Adjust the pH of the system to 6.4-6.6 to form a mixture F. Place the mixture F in a constant temperature water bath at 72.0℃ and sonicate it at a frequency of 40.0kHz for 17.0min.

[0047] S7. Heat the ultrasonicated mixture F from step S6 to 85.0℃ and stir for 12.0 min. During the stirring process, continuously monitor the viscosity of the mixture F until the starch in the mixture F is fully gelatinized and not caramelized.

[0048] S8. The gelatinized mixture F from step S7 is cast onto a clean glass plate using a scraper to obtain a film. The cast film is placed in a forced-air drying oven and dried at 56.0℃ for 18.0h. During the drying process, the surface of the film is checked regularly for cracks and bubbles, and the moisture content of the film is monitored using a rapid moisture analyzer to ensure it meets the standard. After drying, the film is peeled off and cooled at room temperature for 36.0h to eliminate internal stress, thus obtaining a biodegradable film.

[0049] Example 5 like Figure 1 As shown in Embodiment 5 of the present invention, a method for preparing a biodegradable membrane is proposed, comprising the following steps: S0. Weigh the following raw materials by weight: 1.0 part konjac powder, 1.8 times the weight of plant protein of konjac powder, 3.5 times the weight of linear corn starch of konjac powder, 17.5% of the weight of cyclodextrin of konjac powder, and 100.0 times the weight of deionized water of konjac powder.

[0050] S1. Add 1 part of konjac powder to 75.0 times its weight of deionized water and stir at 200.0 r / min for 10.0 min to disperse and obtain solution A.

[0051] S2. Add a 0.5 mol / L sodium periodate solution (1.0 times the mass of konjac powder) to solution A obtained in step S1, heat to 80.0℃ and stir at 300.0 r / min for 4.5 min to obtain solution B.

[0052] S3. Add 1.2 times the mass of sodium periodate solution to solution B obtained in step S2, and continue stirring for 15.0 min to obtain solution C.

[0053] S4. Add 1.8 times the mass of konjac flour to the solution C obtained in step S3 and heat to 81°C. Stir at 5250.0 r / min for 1.7 min to obtain solution D.

[0054] S5. Centrifuge the solution D obtained in step S4 at 9500.0 rpm for 10.0 min to remove residual suspended matter and collect precipitate E.

[0055] S6. Add 3.5 times the mass of konjac powder of linear corn starch, 17.5% of the mass of konjac powder of cyclodextrin, and the precipitate E obtained in step S5 to the remaining deionized water (25.0 times the mass of konjac powder). Adjust the pH of the system to 6.4-6.6 to form a mixture F. Place the mixture F in a constant temperature water bath at 73.0℃ and sonicate it at a frequency of 40.0kHz for 17.0min.

[0056] S7. Heat the ultrasonicated mixture F from step S6 to 84.0℃ and stir for 10 minutes. During the stirring process, continuously monitor the viscosity of the mixture F until the starch in the mixture F is fully gelatinized and not caramelized.

[0057] S8. The gelatinized mixture F from step S7 is cast onto a clean glass plate using a scraper to obtain a film. The cast film is placed in a forced-air drying oven and dried at 56.0℃ for 18.0h. During the drying process, the surface of the film is checked regularly for cracks and bubbles, and the moisture content of the film is monitored using a rapid moisture analyzer to ensure it meets the standard. After drying, the film is peeled off and cooled at room temperature for 30.0h to eliminate internal stress, thus obtaining a biodegradable film.

[0058] Example 6 like Figure 1 As shown, Embodiment Six of the present invention proposes a method for preparing a biodegradable membrane, comprising the following steps: S0. Weigh the following raw materials by weight: 1.0 part konjac powder, 1.5 times the weight of plant protein of konjac powder, 4.5 times the weight of linear corn starch of konjac powder, 20.0% of the weight of cyclodextrin of konjac powder, and 120.0 times the weight of deionized water of konjac powder.

[0059] S1. Add 1 part of konjac powder to 70.0 times its weight of deionized water and stir at 200.0 r / min for 10.0 min to disperse and obtain solution A.

[0060] S2. Add a 0.5 mol / L sodium periodate solution (1.2 times the mass of konjac powder) to solution A obtained in step S1, heat to 80.0℃ and stir at 300.0 r / min for 4.5 min to obtain solution B.

[0061] S3. Add 1.4 times the mass of sodium periodate solution to solution B obtained in step S2, and continue stirring for 13.0 min to obtain solution C.

[0062] S4. Add 1.5 times the mass of konjac powder to the solution C obtained in step S3 and heat to 81°C. Stir at 5500.0 r / min for 1.6 min to obtain solution D.

[0063] S5. Centrifuge the solution D obtained in step S4 at 8000.0 rpm for 13.0 min to remove residual suspended matter and collect precipitate E.

[0064] S6. Add 4.5 times the mass of konjac powder of linear corn starch, 20.0% of the mass of konjac powder of cyclodextrin, and the precipitate E obtained in step S5 to the remaining deionized water (50.0 times the mass of konjac powder). Adjust the pH of the system to 6.4-6.6 to form a mixture F. Place the mixture F in a constant temperature water bath at 70.0℃ and sonicate it at a frequency of 40.0kHz for 17.0min.

[0065] S7. Heat the ultrasonically treated mixture F from step S6 to 84.0℃ and stir for 13 minutes. During the stirring process, continuously monitor the viscosity of mixture F until the starch in mixture F is fully gelatinized and not caramelized.

[0066] S8. The gelatinized mixture F from step S7 is cast onto a clean glass plate using a scraper to obtain a film. The cast film is placed in a forced-air drying oven and dried at 56.0℃ for 18.0h. During the drying process, the surface of the film is checked regularly for cracks and bubbles, and the moisture content of the film is monitored using a rapid moisture analyzer to ensure it meets the standard. After drying, the film is peeled off and cooled at room temperature for 36.0h to eliminate internal stress, thus obtaining a biodegradable film.

[0067] The tensile strength, elongation at break, heat shrinkage rate at 120°C for 30 min, and water vapor transmission rate of the biodegradable films prepared in Examples 1 to 6, as well as existing PLA films, PBAT films, PE films, and PP films, were tested. The PLA films, PBAT films, PE films, and PP films used for testing were all purchased existing products.

[0068] Specifically, the tensile strength and elongation at break tests were conducted according to the national standard GB / T 1040.1-2006 "General Rules for Determination of Tensile Properties of Plastics". The water vapor transmission rate was tested according to the national standard GB / T 21529-2008 "Determination of Water Vapor Transmission Rate of Plastic Films and Sheets - Electrolytic Sensor Method".

[0069] The test results are shown in Table 1 below: Table 1

[0070] As can be seen from the test results in Table 1, the biodegradable films prepared in Examples 1 to 6 have better tensile strength than existing PE and PP films, and their elongation at break and thermal shrinkage are similar to those of existing membrane materials. Furthermore, they exhibit low water vapor permeability. This demonstrates that the biodegradable films prepared in Examples 1 to 6 possess excellent mechanical properties, flexibility, temperature resistance, and barrier properties. Specifically, Examples 1 to 6 utilize natural plant materials such as konjac flour, plant protein, and linear corn starch. Through a multi-component composite system formed by konjac flour, plant protein, starch, and cyclodextrin, and optimized processes including oxidative grafting, ultrasonic dispersion, and gradient drying, biodegradable films with excellent comprehensive performance were obtained.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A biodegradable membrane, characterized in that: By weight, it includes the following components: 1.0 part konjac powder, 1.5-1.8 times the weight of konjac powder of plant protein, 3.5-4.5 times the weight of konjac powder of linear corn starch, 15.0%-20.0% of the weight of konjac powder of cyclodextrin, and 100.0-120.0 times the weight of konjac powder of deionized water.

2. A method for preparing a biodegradable membrane, characterized in that: Includes the following steps: S1. Add konjac powder to deionized water and stir to disperse the konjac powder in the deionized water to obtain solution A; S2. Add sodium periodate solution to solution A obtained in step S1, heat and stir to obtain solution B; S3. Add ethylene glycol solution to solution B obtained in step S2 and continue stirring to obtain solution C; S4. Add plant protein to solution C obtained in step S3, heat and stir to obtain solution D; S5. Centrifuge the solution D obtained in step S4 to remove residual suspended matter and collect precipitate E; S6. Add linear corn starch, cyclodextrin and precipitate E obtained in step S5 to deionized water, adjust the pH of the system to form a mixture F, and place the mixture F in a constant temperature water bath for ultrasonic treatment. S7. Heat and stir the ultrasonically treated mixture F from step S6. Continuously monitor the viscosity of mixture F during stirring until the starch in mixture F is fully gelatinized and not caramelized. S8. Cast the gelatinized mixture F from step S7 onto a clean glass plate to obtain a membrane. After casting, dry the membrane. After drying, peel off the membrane and cool it at room temperature to obtain a biodegradable membrane.

3. The method for preparing a biodegradable membrane as described in claim 2, characterized in that: In step S1, weigh 1 part of konjac powder and 100.0-120.0 times the mass of konjac powder in deionized water. Add 1 part of konjac powder to 70.0-75.0 times the mass of konjac powder in deionized water and stir at 200.0 r / min for 10.0 min to disperse.

4. The method for preparing a biodegradable membrane as described in claim 3, characterized in that: In step 2, add 1.0-1.3 times the mass of konjac powder of a 0.5 mol / L sodium periodate solution, heat to 80.0℃ and stir at 300.0 r / min for 4.5 min.

5. The method for preparing a biodegradable membrane as described in claim 4, characterized in that: In step S3, add 1.2-1.4 times the mass of sodium periodate solution to a 0.5 mol / L ethylene glycol solution and stir for 10.0-15.0 min.

6. The method for preparing a biodegradable membrane as described in claim 2, characterized in that: In step S4, plant protein of 1.5-1.8 times the weight of konjac powder is added to solution C and the temperature is raised to 81°C. The mixture is stirred at a speed of 5500.0±500.0 r / min for 1.5-1.8 min.

7. The method for preparing a biodegradable membrane as described in claim 2, characterized in that: In step S5, solution D is centrifuged at 8000.0-10000.0 rpm for 10.0-13.0 min.

8. The method for preparing a biodegradable membrane as described in claim 3, characterized in that: In step S6, add 3.5-4.5 times the mass of konjac powder of linear corn starch, 15.0%-20.0% of the mass of konjac powder of cyclodextrin, and the precipitate E obtained in step S5 to the remaining deionized water from step S1. Adjust the pH of the system to 6.4-6.6 to form a mixture F. Place the mixture F in a constant temperature water bath at 70.0-73.0℃ and sonicate it at a frequency of 40.0kHz for 17.0min.

9. The method for preparing a biodegradable membrane as described in claim 2, characterized in that: In step S7, the ultrasonically cooled mixture F is heated to 84.0-85.0℃ and stirred for 10.0-13.0 min.

10. The method for preparing a biodegradable membrane as described in claim 2, characterized in that: In step S8, the cast film is placed in a forced-air drying oven and dried at 56.0℃ for 18.0h. During the drying process, the surface of the film is checked regularly for cracks and bubbles, and the moisture content of the film is monitored by a rapid moisture meter to ensure it meets the standard. After the film is removed, it is cooled at room temperature for 24.0-36.0h.

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