Simple degradable waterproof corn stalk-based full-biomass mulching film and preparation method and application thereof

Abstract

The application provides a simple degradable waterproof corn straw-based full-biomass mulch film and a preparation method and application thereof, and belongs to the technical field of agricultural mulch films.The corn straw is crushed to obtain corn straw segments, and the corn straw segments are cooked and pulped to obtain corn straw slurry; the corn straw slurry is formed by papermaking, and the base corn straw mulch film is obtained after drying; and the base corn straw mulch film is modified by polylactic acid to obtain the simple degradable waterproof corn straw-based full-biomass mulch film.The full-biomass degradable biomass mulch film is prepared by skipping the lignin removal process through a simple conventional papermaking process, and the mechanical properties of the biomass mulch film are selectively improved by adding biological glue; the full-biomass mulch film has the functions of traditional mulch film, such as soil conservation and weed inhibition, and has the functions of degradability and environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of agricultural mulch film technology, and particularly relates to a simple, biodegradable, waterproof corn stalk-based fully biocompatible mulch film, its preparation method, and its application. Background Technology

[0002] Mulching is an important measure in modern field management, optimizing water and temperature conditions for crop growth and improving crop yield and quality. More importantly, mulching effectively suppresses weed growth, reducing farmers' weeding burden, increasing labor efficiency, and creating a favorable ecological environment for high crop yields. However, while commonly used traditional plastic mulch films can retain heat and water and promote yield increases, their mechanical recycling increases the burden on farmers, and the long-term accumulation of unrecycled residue leads to soil pollution, resulting in decreased soil fertility and crop quality. To improve sustainable crop production and promote environmental protection, developing biodegradable functional mulch films to replace traditional plastic mulch films is of great significance for modern sustainable agricultural production.

[0003] Currently, the main preparation processes for biodegradable fiber-based mulch films both domestically and internationally include conventional papermaking processes and cellophane production processes. Conventional papermaking processes primarily involve adding cross-linking and plasticizing agents to pulp. This type of process offers advantages such as simplicity and low cost, but its dry and wet strength is suboptimal. Cellophane production processes for mulch films are complex, costly, and also generate pollutants.

[0004] Invention CN120535800A, entitled "A straw fiber-based antibacterial mulch film with temperature and humidity responsive properties and its preparation method," uses palm wax, a fungicide (carbendazim), gelatin, and wheat straw fiber. Invention CN120310016A, entitled "A water-resistant, fully degradable mulch film reinforced with corn straw nanocellulose and its preparation method," prepares nanocellulose through a two-step deep eutectic solvent process, followed by mixing with a silicon source dispersion, PVA, and glycerol. Invention CN120098297A, entitled "A biodegradable slow-release grass-controlling mulch film and its preparation method," is made from biomass carbon, herbicides, and PBAT particles. Invention CN120059601A, entitled "A water-absorbing and water-retaining straw-based biodegradable sprayable mulch film and its preparation method," is made from short straw fibers, a biodegradable superabsorbent resin, and an adhesive. The mulch films of these inventions involve complex preparation processes and use chemical industrial products.

[0005] Therefore, the current method for preparing fiber paper mulch using conventional papermaking processes is relatively mature. However, the preparation process requires the removal of lignin from straw materials and the extraction of cellulose through an alkali process, increasing the complexity of the process. Furthermore, the treatment of alkali lignin also leads to environmental pollution and economic costs. Therefore, this invention proposes a simple, biodegradable, waterproof corn straw-based fully biocompatible mulch, its preparation method, and its applications. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a simple, biodegradable, waterproof corn stalk-based fully biofilm, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] One of the technical solutions of the present invention:

[0009] A simple method for preparing a biodegradable and waterproof corn stalk-based fully biofilm includes the following steps:

[0010] (1) The corn stalks are crushed to obtain corn stalk segments, which are then cooked and pulped to obtain corn stalk slurry;

[0011] (2) The corn stalk slurry is shaped and dried to obtain a basic corn stalk base film;

[0012] (3) Modify the basic corn stalk base film with a biological waterproofing agent to obtain the simple biodegradable waterproof corn stalk base biofilm; the biological waterproofing agent is polylactic acid.

[0013] Furthermore, in step (1), the cooking temperature is 80-120℃.

[0014] Furthermore, in step (1), the fiber particle size in the corn straw slurry is less than 0.60 mm.

[0015] Further, in step (2), the corn stalk slurry is prepared at a concentration of 80-320 g / m³. 2 The quantitative forming process. Quantitative refers to the mass of the inner film per unit area.

[0016] In steps (1)-(2) of this invention, the membrane matrix is ​​constructed using natural components of corn stalks, which simplifies the process while maintaining structural stability. Corn stalks mainly contain cellulose, hemicellulose, and lignin, all of which are natural high molecular polymers. Cellulose is a linear polysaccharide, and its molecules can form tight fiber bundles through hydrogen bonds, which is the "skeleton" of the membrane and provides basic mechanical support. Hemicellulose is a branched polysaccharide with short molecular chains, which can fill the gaps between cellulose fibers and play a "bonding and filling" role, enhancing the bonding force between fibers. Lignin is an aromatic polymer with a rigid structure, which can attach to the cellulose-hemicellulose network and improve the membrane's tensile deformation resistance and weather resistance (such as not easily breaking when blown by wind in the field or pulled by external forces). This invention skips lignin removal, eliminating the need for additional lignin removal steps such as alkali boiling and bleaching. Instead, it directly uses a "crushing-cooking-pulping" process (cooking at 80-120℃ softens the straw fibers and breaks the hydrogen bonds between them, facilitating subsequent papermaking and forming) to allow cellulose, hemicellulose, and lignin to form an "interwoven network" that serves as the substrate for the mulch film. Simultaneously, it utilizes the conventional papermaking process of "papermaking and forming (controlling the basis weight at 80-320g / m²) - drying," a mature and simplified process that avoids the investment in complex equipment, achieving the goal of "preparing the film substrate with a simple process."

[0017] Furthermore, in step (3), the method for modifying the waterproofing agent of the mulch film includes spraying, impregnation and sizing.

[0018] Furthermore, in step (3), the amount of the biological waterproofing agent is 8-70% of the mass of the base corn stalk base film, preferably 10-70%.

[0019] Traditional plastic film mulches primarily function by preventing soil moisture evaporation and by blocking sunlight (inhibiting weed photosynthesis). This invention achieves both functions by modifying polylactic acid (PLA) with hydrophobic properties, combined with the light-blocking properties of the film substrate. PLA is a linear polyester synthesized from lactic acid monomers, possessing adhesive and hydrophobic properties. During modification (spraying, impregnation, or sizing), PLA molecules are adsorbed onto the fiber surface through van der Waals forces, forming a continuous "three-dimensional network hydrophobic layer." This layer covers the hydrophilic groups on the fiber surface or increases the surface tension of water droplets on the mulch film. The hydrophobic layer significantly reduces the hydrophilicity and permeability of the mulch film. Soil moisture cannot evaporate through the micropores of the film (water molecules are blocked by the hydrophobic polyester), while rainwater can slowly permeate through the film's tiny pores (preventing water accumulation), thus maintaining soil moisture and achieving "moisture retention." Secondly, the mulch film substrate is a continuous and dense film that can completely block sunlight and prevent weeds under the film from receiving the light required for photosynthesis. On the other hand, the waterproof modified film can maintain its structural integrity for a long time (not easily damaged by rainwater soaking), and while continuously blocking light, it maintains stable soil moisture, further inhibiting the germination and growth of weeds (weed germination requires light and suitable humidity, and the mulch film can cut off the light conditions).

[0020] Furthermore, in step (3), the quantitative amount of the simple biodegradable waterproof corn stalk-based fully biocompatible mulch film is 80-320 g / m³. 2 .

[0021] Furthermore, in step (2), the corn stalk slurry also includes agar biogel, and the amount of agar biogel added is 0-60% of the dry weight of the corn stalk (it can be 0).

[0022] This invention selectively incorporates agar (agar-based adhesive) to improve mechanical properties, enhancing inter-fiber bonding through hydrogen bonding and addressing the mechanical deficiencies of pure straw films. Agar is a natural marine polysaccharide, primarily composed of agarose (linear polysaccharide) and agar gum (branched polysaccharide containing sulfate groups). Its molecular chains are rich in hydroxyl groups (-OH), exhibiting strong hydrophilicity and adhesiveness. When agar is added to corn straw slurry at a ratio of 0-60%, the hydroxyl groups of agar molecules form strong hydrogen bonds with the hydroxyl groups of cellulose and hemicellulose molecules, effectively building "bonding bridges" between "cellulose fiber bundles." The addition of agar prevents easy slippage between fibers, significantly improving the tensile strength and elongation at break of the film. Simultaneously, the gelling properties of agar enhance the film's flexibility, preventing breakage due to brittleness during field installation. The amount of agar added is 0-60%, which can be adjusted according to the mechanical requirements of the mulch film (for example, in arid areas where a more tensile-resistant mulch film is needed, the amount of agar added can be increased; in humid areas where the mechanical requirements are lower, the amount added can be reduced or not added), thus achieving "improving mechanical properties as needed".

[0023] The second technical solution of the present invention:

[0024] A simple, biodegradable, waterproof corn stalk-based fully biofilm was prepared according to the above preparation method.

[0025] The simple, biodegradable, waterproof corn stalk-based fully biodegradable mulch membrane of this invention is rich in cellulose and hemicellulose, which can be broken down into small-molecule sugars such as glucose and xylose by cellulase and hemicellulase in the soil, and further metabolized into CO2 and H2O by microorganisms. Although lignin degrades more slowly, lignin-degrading bacteria in the soil can gradually decompose its aromatic ring structure into small-molecule organic matter through the secretion of laccase and peroxidase, which is eventually integrated into the soil. The raw material, agar biogel, is a natural polysaccharide that can be broken down into monosaccharides such as galactose by polysaccharide-degrading enzymes (such as agarase) in the soil, and then utilized by microorganisms without residue. The added polylactic acid is a biodegradable material polymerized by ester bonds, which can be metabolized into CO2 and H2O through hydrolysis and microbial action, and will not accumulate in the soil. Therefore, the fully biodegradable mulch membrane of this invention has biodegradable properties.

[0026] The third technical solution of the present invention:

[0027] The above-mentioned simple biodegradable waterproof corn stalk-based fully bio-based mulch film can be used in agricultural mulching, for example, for water retention, heat preservation, soil plastic reduction and crop yield promotion during the agricultural mulching process.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] This invention prepares a fully biodegradable biomass mulch film using a simple and conventional papermaking process, skipping the lignin removal process. It selectively attaches bio-adhesive to improve the mechanical properties of the biomass film and prepares a film that combines the moisture retention and weed suppression functions of traditional mulch films with biodegradable and environmentally friendly features through a waterproof modification process. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0031] Figure 1 This is a schematic diagram of the preparation process of the simple biodegradable and waterproof corn stalk-based fully biofilm of the present invention.

[0032] Figure 2 The effect of fiber particle size in corn straw slurry on the mechanical properties of basic corn straw base film is shown, where (a) is tensile force and (b) is tensile strength.

[0033] Figure 3 The effect of biofilm on the mechanical properties of base corn stalk film was quantitatively determined, where (a) is tensile force and (b) is tensile strength.

[0034] Figure 4 The effect of the amount of agar bio-gel added on the mechanical properties of the base corn stalk base film is shown in Figure 1, where (a) is the tensile force and (b) is the tensile strength.

[0035] Figure 5 The mechanical properties of the polylactic acid-modified simple biodegradable waterproof corn stalk-based all-biofilm prepared in Example 1 (after modification) and the basic corn stalk-based film prepared in Comparative Example 1 (before modification) under dry and wet conditions are shown in (a) for tensile force and (b) for tensile strength.

[0036] Figure 6 The results are the water retention and heat preservation performance test results of the membranes of Example 1, Comparative Example 1, and Comparative Example 2, where (a) is the water retention performance test result and (b) is the heat preservation performance test result.

[0037] Figure 7 Water resistance test results of biofilms in Examples 2-7 and Comparative Examples 1 and 3-5.

[0038] Figure 8 The results of thermogravimetric and micro-tuberculous thermogravimetric tests for the membranes of Example 1 and Comparative Example 1 and polylactic acid are shown, where (a) is the weight loss rate test result and (b) is the weight change rate test result.

[0039] Figure 9 (a) is an optical micrograph of the composition of corn stalk slurry used for film preparation; (b) is an optical micrograph of the composition of pure corn stalk fibers after purification; (c) is a scanning electron microscope image of the surface of the whole biofilm before modification; (d) is a scanning electron microscope image of the surface of the modified corn stalk-based whole biofilm; (e) is the surface network micropores of the modified corn stalk-based whole biofilm; (f) is the coating thickness of polylactic acid on the surface of the modified corn stalk-based whole biofilm. Detailed Implementation

[0040] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0041] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0042] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0043] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0044] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0045] This invention provides a simple method for preparing a biodegradable and waterproof corn stalk-based fully biofilm. A flowchart is shown below. Figure 1 Specifically, it includes the following steps:

[0046] (1) The corn stalks are crushed to obtain corn stalk segments, which are then cooked and pulped to obtain corn stalk slurry;

[0047] (2) The corn stalk slurry is shaped and dried to obtain the basic corn stalk base film;

[0048] (3) Modify the basic corn stalk base film with a biological waterproofing agent to obtain a simple biodegradable waterproof corn stalk base biofilm; the biological waterproofing agent is polylactic acid.

[0049] In step (1) of the preferred embodiment of the present invention, the cooking temperature is 80-120℃.

[0050] In step (1) of the preferred embodiment of the present invention, the fiber particle size in the corn straw slurry is less than 0.6 mm.

[0051] In step (2) of the preferred embodiment of the present invention, the corn straw slurry is prepared at a concentration of 80-320 g / m³. 2 The quantitative copying and forming process.

[0052] In step (3) of the preferred embodiment of the present invention, the method for modifying the biological waterproofing agent includes spraying, impregnation and sizing.

[0053] In step (3) of the preferred embodiment of the present invention, the amount of biological waterproofing agent used is 8-70% of the mass of the base corn stalk base film, preferably 10-70%.

[0054] In step (3) of the preferred embodiment of the present invention, the quantitative amount of the simple biodegradable waterproof corn stalk-based biofilm is 80-320 g / m³. 2 .

[0055] In step (2) of the preferred embodiment of the present invention, the corn stalk slurry also includes agar biogel, and the amount of agar biogel added is 0-60% (can be 0) of the dry weight of the corn stalk.

[0056] This invention also proposes a simple, biodegradable, waterproof corn stalk-based fully biofilm, which is prepared according to the above preparation method.

[0057] This invention also proposes an application of the above-mentioned simple, biodegradable, waterproof corn stalk-based fully biofilm in agricultural mulching, for example, it can be used for water retention, heat preservation, soil plastic reduction, and crop yield promotion during the agricultural mulching process.

[0058] The method for preparing a simple, biodegradable, waterproof corn stalk-based fully biofilm proposed in this invention can also be applied to wheat stalks and rice stalks.

[0059] All raw materials used in the embodiments of this invention were purchased commercially.

[0060] The technical solution of the present invention will be further illustrated by the following embodiments.

[0061] Example 1

[0062] A simple method for preparing a biodegradable and waterproof corn stalk-based fully biofilm includes the following steps:

[0063] (1) Crush corn stalks to 0-10cm to obtain corn stalk segments, cook at 80-120℃ for 5h, use a Wali pulper and fiber sieve to hydraulically screen to obtain corn stalk slurry with fiber particle size less than 0.6mm, add agar biogel to the corn stalk slurry, the amount of agar biogel added is 0-60% of the dry weight of corn stalks;

[0064] (2) Dissolve the corn stalk slurry obtained in step (1) at a concentration of 80-320 g / m³. 2 The corn stalks are quantitatively shaped and dried under vacuum pressure. The basic corn stalk base film is naturally synthesized through physical cross-linking and molecular hydrogen bonding between corn stalks.

[0065] (3) Modify the basic corn stalk base film obtained in step (2) with polylactic acid by spraying, impregnation or sizing. The amount of polylactic acid used is 8-70% of the mass of the basic corn stalk base film, and the resulting product has a quantitative value of 80-320 g / m³. 2 A simple, biodegradable, waterproof corn stalk-based, fully biocompatible membrane modified with polylactic acid.

[0066] The parameters for steps (1) and (2) are respectively limited as follows: cooking at 100℃ for 5 hours, adding agar biogel at 0% of the dry weight of corn stalks, and adding the corn stalk slurry obtained in step (1) at 120g / m 2 Based on steps (1) and (2) in Example 1, the fiber particle size in the corn straw slurry was changed (i.e., corn straw slurry with fiber particle sizes of 0.60-1.18 mm, 0.30-0.60 mm, 0.15-0.30 mm, and 0.11-0.15 mm were obtained by hydraulic screening) to prepare a basic corn straw base film, and mechanical properties were tested. The results are shown in […]. Figure 2Where (a) is tensile strength and (b) is tensile strength, it can be seen that the mechanical properties of biomass films prepared from straw slurry of different particle sizes are as follows from largest to smallest: 0.15-0.30 mm (10.2N) > 0.30-0.60 mm (10.0N) > 0.11-0.15 mm (9.09N) > 0.60-1.18 mm (6.57N).

[0067] The parameters for steps (1) and (2) were set as follows: cooking at 100℃ for 5 hours, adding agar biogel at 0% of the dry weight of corn straw, and obtaining corn straw slurry with a fiber particle size of <0.30 mm by hydraulic screening. Based on steps (1) and (2) in Example 1, the biofilm quantification was changed (i.e., the corn straw slurry obtained in step (1) was prepared at 120, 180, 240, and 300 g / m³ respectively). 2 A basic corn stalk base film was prepared by quantitative papermaking and molding, and its mechanical properties were tested. The results are shown in […]. Figure 3 Where (a) is tensile strength and (b) is tensile force, it can be seen that increasing the biofilm quantitation to 300 g / m³ is effective. 2 The mechanical properties are significantly improved, and the appropriate amount can be used according to the specific application scenario requirements.

[0068] The parameters for steps (1) and (2) are respectively limited as follows: cooking at 100℃ for 5 hours, obtaining corn straw slurry with a fiber particle size of <0.30 mm by hydraulic screening, and applying the corn straw slurry obtained in step (1) at 120 g / m 2 Based on steps (1) and (2) in Example 1, the amount of agar bio-glue added was changed (i.e., the amount of agar bio-glue added was 0%, 10%, 20%, 40%, and 60% of the dry weight of corn stalks) to prepare a basic corn stalk base film, and mechanical properties were tested. The results are shown in […]. Figure 4 Where (a) is tensile force and (b) is tensile strength, it can be seen that the mechanical properties of biofilm increase with the increase of agar biogel addition, and the mechanical properties of biofilm can be improved as needed.

[0069] The parameters for steps (1) and (2) are respectively limited as follows: cooking at 100℃ for 5 hours, obtaining corn straw slurry with a fiber particle size of <0.60 mm by hydraulic screening, and applying the corn straw slurry obtained in step (1) at 120 g / m 2 The basic corn stalk base film was prepared by quantitatively taking and shaping the film and adding bio-adhesive at 0% of the dry weight of corn stalks. Then, according to step (3), the basic corn stalk base film obtained in step (2) was modified with polylactic acid by impregnation. The amount of polylactic acid used was 30% of the mass of the basic corn stalk base film, resulting in a quantitative yield of 160 g / m³. 2A simple, biodegradable, waterproof corn stalk-based, fully biocompatible membrane modified with polylactic acid.

[0070] Examples 2-7

[0071] Based on the preparation of a simple biodegradable and waterproof corn stalk-based biofilm modified with polylactic acid in Example 1, the amount of polylactic acid was changed to 10%, 25%, 35%, 45%, 56%, and 70% of the mass of the corn stalk-based biofilm.

[0072] Comparative Example 1

[0073] Same as Example 1, except that polylactic acid was not added for modification, resulting in the unmodified corn stalk base film. The specific preparation method is as follows:

[0074] (1) Corn stalks were crushed to 0-10cm to obtain corn stalk segments, cooked at 100℃ for 5h, and then hydraulically screened using a Wali pulper and fiber sieve to obtain corn stalk slurry with a fiber particle size of <0.60 mm. Agar biogel was added to the corn stalk slurry at a rate of 0% of the dry weight of the corn stalks.

[0075] (2) The corn stalk slurry obtained in step (1) is mixed at a concentration of 120 g / m³. 2 The corn stalks are quantitatively shaped and dried under vacuum pressure. The basic corn stalk base film is naturally synthesized through physical cross-linking and molecular hydrogen bonding between corn stalks.

[0076] Comparative Example 2

[0077] PE film (polyethylene film).

[0078] Comparative Examples 3-5

[0079] Based on the preparation of a simple biodegradable and waterproof corn stalk-based biofilm modified with polylactic acid in Example 1, the amount of polylactic acid was changed to 2%, 4%, and 6% of the mass of the corn stalk-based biofilm.

[0080] Performance testing

[0081] (1) Mechanical property testing

[0082] Mechanical properties of the polylactic acid-modified simple biodegradable waterproof corn stalk-based all-biofilm prepared in Example 1 (after modification) and the basic corn stalk-based film prepared in Comparative Example 1 (before modification) were tested under dry and wet conditions. The results are shown in the figure. Figure 5 Where (a) is tensile strength and (b) is tensile force; it can be seen that the mechanical properties of the biofilm are almost lost when wet, but the mechanical properties of the biofilm are improved by 1.82-2.09 times after polylactic acid modification. The mechanical properties of the polylactic acid modified biofilm can meet the requirements of field mechanized operations.

[0083] (2) Water retention and heat preservation performance test

[0084] Test methods: Water retention performance was determined by gravimetric method, and thermal insulation performance was evaluated by using a "time-temperature" curve of temperature drop from 60℃ to 20℃ with a pre-embedded temperature probe.

[0085] Test subjects: the membranes of Example 1, Comparative Example 1, and Comparative Example 2, and a blank group without membrane covering.

[0086] The test results of the water retention and heat preservation performance of the membranes in Example 1, Comparative Example 1, and Comparative Example 2 are shown in the figure. Figure 6 (a) shows the water retention performance test results, and (b) shows the heat insulation performance test results. It can be seen that polylactic acid modification can improve the water retention performance of biomass membrane by more than 2 times; compared with the blank control group, the membrane has a heat insulation effect, but the difference in heat insulation performance between the membrane before and after modification is not significant.

[0087] (3) Waterproof performance test

[0088] Test method: Observation method. Use a pipette to place a 20µL droplet on the membrane surface and observe the capillary phenomenon of the liquid on the biomass membrane.

[0089] Test subjects: the membranes of Example 1 and Comparative Example 1.

[0090] The water resistance test results of the biofilms in Examples 2-7, Comparative Examples 1, and 3-5 are shown below. Figure 7 The first row, from left to right, represents Comparative Example 1, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Example 2. The second row, from left to right, represents Example 3, Example 4, Example 5, Example 6, and Example 7. It can be seen that polylactic acid modification can eliminate capillary action on the surface of the biomass film, slow down water evaporation, and improve water retention, which is beneficial for water retention during field mulching. In contrast, Comparative Example 1, without added polylactic acid, exhibits significant capillary action, with water rapidly diffusing to the biofilm; the water evaporates within 10 minutes at 30°C, resulting in poor water retention.

[0091] (4) Degradation performance test

[0092] Test methods: thermogravimetric analysis and micro-business thermogravimetric analysis.

[0093] Test subjects: the membranes of Example 1 and Comparative Example 1 (referred to as polylactic acid modified straw and corn straw, respectively) and polylactic acid.

[0094] The thermogravimetric and micro-thermogravimetric test results of the membranes of Example 1 and Comparative Example 1, as well as polylactic acid, are shown in the figure. Figure 8(a) shows the weight loss rate test results, and (b) shows the weight change rate test results. It can be seen that there are significant differences in the thermal stability of the three materials. The maximum weight loss rate temperature of polylactic acid (PLA) is 322℃. Comparative Example 1 shows two weight loss stages; the first weight loss peak temperature is relatively low (309℃), corresponding to the thermal decomposition of unstable components in biomass, indicating that these components have poor thermal stability. The second weight loss peak temperature is 363℃. Comparative Example 1 has a high ash content (18.7%), confirming its biomass origin. The maximum weight loss rate temperature of Example 1 is 355℃, with a single main peak, indicating that PLA modification can improve the overall stability of the composite material. In summary, the biodegradability is in the order of PLA < Example 1 < Comparative Example 1 membrane. The biodegradability of the PLA-modified biomass membrane is between that of PLA and the unmodified biomass membrane.

[0095] In Example 1, during the preparation of a simple, biodegradable, waterproof corn stalk-based all-biofilm modified with polylactic acid, the optical micrograph of the corn stalk slurry obtained is shown below. Figure 9 (a) See the optical micrograph of pure corn stalk fiber after alkali purification. Figure 9 (b) The surface scanning electron microscope image of the whole biofilm before modification is shown in Figure 1. Figure 9 (c) The surface scanning electron microscope image of the modified corn straw-based all-biofilm is shown in Figure 1. Figure 9 In the middle (d), the surface network micropores of the modified corn straw-based all-biofilm are observed. Figure 9 In section (e), the coating thickness of polylactic acid on the surface of the modified corn stalk-based biofilm is shown in [reference]. Figure 9 (f) It can be seen that corn straw slurry is a mixture of cellulose, biomass cell walls, and biomass residue. Figure 9 (a) After the corresponding alkaline removal of lignin and hemicellulose, the purified straw cellulose composition is relatively uniform. Figure 9 (b) The surface of the biomass membrane after polylactic acid modification undergoes significant changes, uniformly coated with a three-dimensional network hydrophobic coating with a diameter of approximately 10µm and a thickness of 5-14µm, which improves the mechanical and water retention properties of the biomass membrane.

[0096] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A simple method for preparing a biodegradable and waterproof corn stalk-based fully biocompatible mulch film, characterized in that, Includes the following steps: (1) The corn stalks are crushed to obtain corn stalk segments, which are then cooked and pulped to obtain corn stalk slurry. The cooking temperature is 80-120℃. (2) The corn straw slurry is prepared at a concentration of 80-320 g / m³. 2 The quantitative papermaking and drying process yields a basic corn stalk base film. (3) Modify the basic corn stalk base film with a biological waterproofing agent to obtain the simple biodegradable waterproof corn stalk-based fully biodegradable base film; the biological waterproofing agent is polylactic acid; In step (2), the corn stalk slurry also includes agar biogel, and the amount of agar biogel added is 0-60% of the dry weight of the corn stalk; In step (3), the method for modifying the biological waterproofing agent includes spraying, impregnation, and sizing. The amount of the biological waterproofing agent used is 8-70% of the mass of the base corn stalk base film. In step (1), the cooking time is 1-5 hours, and the fiber particle size in the corn straw slurry is less than 0.6 mm.

2. A simple, biodegradable, waterproof corn stalk-based, fully biocompatible membrane, characterized in that: It is prepared according to the preparation method described in claim 1.

3. The application of the simple, biodegradable, waterproof corn stalk-based fully biofilm as described in claim 2 in agricultural mulching.

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