A fully biodegradable material based on bamboo fibers and a method for preparing the same

Abstract

The application discloses a kind of full biodegradable materials based on bamboo fiber and preparation method thereof, belong to composite material technical field.Preparation method includes the following steps:First, epoxy soybean oil is mixed with kaolin and is treated by ultrasonic, to obtain dispersion material;Second, after bamboo fiber is crushed and dehydrated, it is mixed in the aqueous solution of fluorine ammonium compound and imidazole salt, heating reflux, filter collection insoluble and wash dry, to obtain modified bamboo fiber;Finally, modified bamboo fiber, dispersion material, polylactic acid, calcium carbonate, vinyl bis stearyl amide, glycerol triacetate and sorbitol are mixed, are put into twin-screw extruder, temperature and extrusion process parameters are controlled, by vacuum mold cooling, to obtain full biodegradable material.Compared with prior art, the material of the application can be quickly decomposed under composting conditions, reducing the impact on the environment, while optimizing the surface properties of the material, expanding its application range.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, and in particular to a fully biodegradable material based on bamboo fiber and its preparation method. Background Technology

[0002] With increasing global attention to environmental protection and sustainable development, the pollution caused by traditional plastic products has become increasingly prominent. Traditional plastics are difficult to degrade naturally, accumulating in the environment over time, occupying vast amounts of land resources and causing serious harm to soil, water sources, and ecosystems. Therefore, the development and application of fully biodegradable materials has become one of the important ways to solve the problem of plastic pollution. Fully biodegradable materials can be completely decomposed into carbon dioxide and water in the natural environment through the action of microorganisms, making them environmentally friendly and possessing broad application prospects.

[0003] Despite progress in the research and application of fully biodegradable materials, existing technologies still have some shortcomings. For example, some fully biodegradable materials degrade slowly, making it difficult to meet the requirements of rapid composting; some materials have poor mechanical and processing properties, limiting their widespread use in practical applications; and some materials perform poorly in terms of hydrophilicity and wettability, affecting their performance in specific application scenarios. Furthermore, the complex and costly preparation processes of existing fully biodegradable materials also hinder their large-scale promotion and application.

[0004] Bamboo fiber, as a natural biomass material, possesses high strength, good biodegradability, and renewability, and is widely used in the preparation of fully biodegradable materials. However, the surface properties of bamboo fiber (such as hydrophobicity) and its compatibility with polymer matrices limit its application in fully biodegradable materials. Therefore, improving the compatibility of bamboo fiber with polymer matrices and enhancing the overall performance of materials through effective surface modification techniques has become an important research direction.

[0005] Among existing technologies for preparing fully biodegradable materials, Chinese invention patent application CN101914293A discloses the use of nano-silica to modify bamboo fiber. While this improves mechanical strength, it does not solve the problems of poor water absorption and low biodegradation rate caused by hemicellulose clogging the pores in bamboo fiber. Chinese invention patent application CN104804387A discloses the direct blending of bamboo fiber with polylactic acid. Although this achieves complete degradation, the hydrophobic surface of the unmodified bamboo fiber limits hydrophilicity and microbial adhesion efficiency, leading to a prolonged degradation cycle.

[0006] Therefore, it is crucial to develop a highly efficient, environmentally friendly, and fully biodegradable material with excellent overall performance. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention aims to provide a fully biodegradable material based on bamboo fiber and its preparation method.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A method for preparing a fully biodegradable material based on bamboo fiber is as follows:

[0010] Step 1: Mix epoxidized soybean oil and kaolin with ultrasonic treatment to uniformly disperse and obtain a dispersion.

[0011] Step 2: After crushing and dehydrating the bamboo fiber, add it to an aqueous solution of ammonium fluoride compound and imidazole salt, mix, heat and reflux, filter to collect the insoluble matter and wash, and dry to obtain modified bamboo fiber.

[0012] Step 3: Mix modified bamboo fiber, dispersion, polylactic acid, calcium carbonate, vinyl bis-stearamide, glyceryl triacetate, and sorbitol to obtain a mixture; feed the mixture into a twin-screw extruder, control the temperature and extrusion process parameters, and cool and shape it through a vacuum die to obtain a fully biodegradable material.

[0013] Preferably, the preparation method of the fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0014] Step 1: Mix 1-3 parts of epoxidized soybean oil with 2-4 parts of kaolin and ultrasonically treat to uniformly disperse, thus obtaining a dispersion.

[0015] Step 2: Crush 80-120 parts of bamboo fiber to 100-200 mesh and dehydrate; add 20-30 parts of ammonium fluoride compound and 15-20 parts of imidazole salt to 500-1000 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to reflux, then filter to collect the insoluble matter and wash with water and ethanol 1-3 times each, then place in a constant temperature oven at 70-100℃ and dry for 5-24 hours to obtain modified bamboo fiber;

[0016] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 20-40 parts of polylactic acid, 3-8 parts of calcium carbonate, 1-5 parts of vinyl bis-stearamide, 1-3 parts of glyceryl triacetate, and 2-8 parts of sorbitol. The mixing temperature is 100-140℃, the mixing speed is 300-800 rpm, and the time is 5-30 minutes to obtain a mixture. Put the mixture into a twin-screw extruder, control the temperature and extrusion process parameters, and cool and shape it through a vacuum die to obtain a fully biodegradable material.

[0017] In step 1, the ultrasonic time is 3-8 minutes, the ultrasonic power is 800-1200W, and the ultrasonic frequency is 20-60kHz.

[0018] The dehydration in step 2 involves stirring and dehydrating at 80-100℃ and 200-500 rpm until the moisture content is 1-3%.

[0019] In step 2, the heating and reflux process involves heating to 60-70℃ and refluxing for 1-3 hours.

[0020] In step 3, the temperature of the twin-screw extruder is controlled in 5 segments: 110-130℃, 130-150℃, 140-160℃, 150-170℃, and 140-160℃.

[0021] The extrusion process parameters of the twin-screw extruder in step 3 are: main machine speed: 20-30 rpm, material pressure: 1.5-2.5 MPa.

[0022] The ammonium fluoride compound is one of ammonium fluoride, ammonium hydrofluoride, and ammonium fluoroborate.

[0023] The imidazole salt is one of 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, and 1-allyl-3-methylimidazolium glycinate.

[0024] The functions of each substance are as follows:

[0025] Bamboo fiber, as a biomass matrix material, provides a biodegradable skeleton and reinforcing structure.

[0026] Ammonium fluoride compounds catalyze the hydrolysis of hemicellulose by etching the fiber surface to expose hydroxyl groups and modulating a slightly acidic environment.

[0027] The role of imidazole salts is as an ionic liquid modifier. Through the formation of hydrogen bond networks between their anions and the hydroxyl groups in bamboo fibers, they significantly enhance the hydrophilicity and biodegradability of the material.

[0028] Epoxidized soybean oil and kaolin synergistically improve dispersibility and enhance the interfacial compatibility of composite materials.

[0029] Kaolin, as an inorganic reinforcing phase, improves the mechanical strength and thermal stability of materials.

[0030] Polylactic acid (PLA), as a biodegradable polymer matrix, endows materials with molding ability and initial strength.

[0031] Calcium carbonate serves as a low-cost filler, reducing material density and regulating melt flowability.

[0032] Vinyl bis-stearamide acts as a lubricant and release agent, reducing processing friction and preventing sticking.

[0033] Glyceryl triacetate acts as a plasticizer, improving the flexibility and compatibility of PLA and bamboo fiber.

[0034] Sorbitol, as a hydrophilic plasticizer, promotes molecular chain movement and assists in microbial degradation.

[0035] Water is used as a solvent in the modification stage, and water / ethanol is used in the washing stage to remove residual impurities.

[0036] Compared with existing technologies, it has the following advantages:

[0037] 1) This invention significantly improves the biodegradability of fully biodegradable materials by combining specific fluorinated ammonium compounds and imidazole salts, enabling them to decompose more quickly under composting conditions and reducing their impact on the environment.

[0038] 2) This invention optimizes the surface properties of the material, reduces the water contact angle, and improves the hydrophilicity of the material, giving it better wettability and water absorption capacity in humid environments, thus expanding the application range of the material.

[0039] 3) This invention enhances the mechanical and processing properties of composite materials through optimized formulation and processing, enabling them to perform well in various application scenarios while maintaining good biodegradability and hydrophilicity. Detailed Implementation

[0040] Main source of materials:

[0041] Bamboo fiber, 60-110mm, average fineness: 6dtex, Guangzhou Jinsheng Technology Co., Ltd.

[0042] Epoxidized soybean oil, product code: LS87-200, Shenzhen Donggangtian Chemical Co., Ltd.

[0043] Kaolin, particle size: 3250 mesh, color: white, viscosity: 220, item number: 133, Lingshou County Yanbo Mineral Products Processing Plant.

[0044] Polylactic acid, brand name: REVODE110, Suzhou Jiangcangfa Plastics Co., Ltd.

[0045] Calcium carbonate, product specifications: 1250 mesh, item number: 2021-66, Wuhan Hengguan New Material Technology Co., Ltd.

[0046] All other raw materials used in the embodiments and comparative examples of this invention are commercially available products. Example 1

[0047] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0048] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0049] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; add 25 parts of ammonium fluoride and 18 parts of 1-allyl-3-methylimidazolium glycinate to 800 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to 65℃ and reflux for 2 hours, then filter to collect the insoluble matter and wash three times each with water and ethanol, and then dry in a 90℃ constant temperature oven for 12 hours to obtain modified bamboo fiber;

[0050] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained. Example 2

[0051] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0052] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0053] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; add 25 parts of ammonium fluoride and 18 parts of 1-butyl-3-methylimidazolium chloride to 800 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to 65℃ and reflux for 2 hours, then filter to collect the insoluble matter and wash three times each with water and ethanol, and then dry in a constant temperature oven at 90℃ for 12 hours to obtain modified bamboo fiber;

[0054] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained. Example 3

[0055] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0056] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0057] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; add 25 parts of ammonium fluoride and 18 parts of 1-ethyl-3-methylimidazolium acetate to 800 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to 65℃ and reflux for 2 hours, then filter to collect the insoluble matter and wash three times each with water and ethanol, and then dry in a 90℃ constant temperature oven for 12 hours to obtain modified bamboo fiber;

[0058] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained. Example 4

[0059] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0060] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0061] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; add 25 parts of ammonium fluoroborate and 18 parts of 1-allyl-3-methylimidazolium glycinate to 800 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to 65℃ and reflux for 2 hours, then filter to collect the insoluble matter and wash three times each with water and ethanol, and then dry in a 90℃ constant temperature oven for 12 hours to obtain modified bamboo fiber;

[0062] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained. Example 5

[0063] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0064] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0065] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; add 25 parts of ammonium fluoride and 18 parts of 1-allyl-3-methylimidazolium glycinate to 800 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to 65℃ and reflux for 2 hours, then filter to collect the insoluble matter and wash three times each with water and ethanol, and then dry in a 90℃ constant temperature oven for 12 hours to obtain modified bamboo fiber;

[0066] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained. Example 6

[0067] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0068] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0069] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; add 25 parts of ammonium fluoride and 18 parts of 1-ethyl-3-methylimidazolium acetate to 800 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to 65℃ and reflux for 2 hours, then filter to collect the insoluble matter and wash three times each with water and ethanol, and then dry in a constant temperature oven at 90℃ for 12 hours to obtain modified bamboo fiber;

[0070] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained.

[0071] Comparative Example 1

[0072] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0073] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0074] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; add 25 parts of ammonium fluoride and 18 parts of 1,1-butyl-3-methylimidazolium trifluoroacetate to 800 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to 65℃ and reflux for 2 hours, then filter to collect the insoluble matter and wash three times each with water and ethanol, and then dry in a constant temperature oven at 90℃ for 12 hours to obtain modified bamboo fiber;

[0075] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained.

[0076] Comparative Example 2

[0077] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0078] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0079] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; add 25 parts of tetrabutylammonium fluoride and 18 parts of 1-allyl-3-methylimidazolium glycinate to 800 parts of water to obtain a mixed solution; add the dehydrated bamboo fiber to the mixed solution and mix, then heat to 65℃ and reflux for 2 hours, then filter to collect the insoluble matter and wash three times each with water and ethanol, and then dry in a 90℃ constant temperature oven for 12 hours to obtain modified bamboo fiber;

[0080] Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained.

[0081] Comparative Example 3

[0082] A method for preparing a fully biodegradable material based on bamboo fiber is as follows, in parts by weight:

[0083] Step 1: Mix 2 parts of epoxidized soybean oil and 3 parts of kaolin, and sonicate for 5 minutes at an ultrasonic power of 1000W and an ultrasonic frequency of 60kHz to obtain a uniform dispersion.

[0084] Step 2: Crush 100 parts of bamboo fiber to 150 mesh, stir and dehydrate at 90℃ and 400 rpm until the moisture content is 2%; then dry in a 90℃ constant temperature oven for 12 hours to obtain bamboo fiber.

[0085] Step 3: Mix the bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 30 parts polylactic acid, 5 parts calcium carbonate, 3 parts vinyl bis-stearamide, 2 parts glyceryl triacetate, and 5 parts sorbitol. The mixing temperature is 120℃, the mixing speed is 600 rpm, and the time is 15 minutes to obtain a mixture. Feed the mixture into a twin-screw extruder, and control the temperature in 5 stages: 120℃, 140℃, 155℃, 160℃, and 150℃. The extrusion process parameters are: main extruder speed: 25 rpm, material pressure: 2.2 MPa. After cooling and shaping in a vacuum mold, a fully biodegradable material is obtained.

[0086] Test Example 1

[0087] Biodegradability performance test:

[0088] To accurately evaluate the biodegradability of the materials, composting degradation tests were conducted according to GB / T 19277.1-2011, "Determination of the final aerobic biodegradability of materials under controlled composting conditions—Method for determining the release of carbon dioxide—Part 1: General Method". During the tests, the fully biodegradable materials prepared in the embodiments and comparative examples of this invention were thoroughly mixed with composting inoculum and placed in a dedicated composting container. Under conditions ensuring good oxygenation, the temperature inside the container was precisely controlled at 58±2℃, and the humidity was maintained between 50% and 55%, allowing the materials to undergo thorough composting treatment in this environment. After six months of continuous monitoring and observation, the biodegradation rate of the materials during this period was calculated. The relevant test data are recorded in detail in Table 1, providing an important basis for subsequent performance analysis and evaluation.

[0089] Table 1

[0090] Experimental protocol Biodegradation rate / % Example 1 88.2 Example 2 78.5 Example 3 85.3 Example 4 82.1 Example 5 90.5 Example 6 86.7 Comparative Example 1 83.5 Comparative Example 2 87.8 Comparative Example 3 72.3

[0091] Test Example 2

[0092] Contact angle test:

[0093] The water contact angle of the fully biodegradable materials prepared in the embodiments and comparative examples of this invention was accurately measured using a contact angle meter. Before testing, these materials were fixed flat on the surface of a glass slide. To ensure the accuracy of the data, measurements were taken at five different locations for each group of materials, and the average value of these five measurement points was taken as the water contact angle value of the material. Detailed measurement results are recorded in Table 2, providing key basis for subsequent analysis of the film surface properties.

[0094] Table 2

[0095] Experimental protocol Water contact angle ° Example 1 38.5 Example 2 52.7 Example 3 36.2 Example 4 43.8 Example 5 34.1 Example 6 32.7 Comparative Example 1 48.3 Comparative Example 2 41.6 Comparative Example 3 64.5

[0096] In the analysis of the mechanism of action of different imidazole salts based on the ammonium fluoride system on biodegradation rate and water contact angle, 1-allyl-3-methylimidazolium glycine salt (Example 1) showed a high biodegradation rate (88.2%). Its glycine anion (Gly⁻) can accelerate the reproduction of microorganisms as a nitrogen source. In terms of water contact angle (38.5°), the amino (-NH₂) and carboxyl (-COOH) groups of glycine form a hydrogen bond network with the hydroxyl groups of cellulose, which increases the density of hydrophilic groups. 1-butyl-3-methylimidazolium chloride salt (Example 2) had a biodegradation rate of 78.5%. Chloride ions (Cl⁻) inhibited the activity of actinomycetes, and residual chlorinated organic matter (such as chloroform byproducts) hindered the enzyme-catalyzed reaction. Its water contact angle was 52.7°. Cl⁻ adsorbed on the fiber surface to form hydrophobic spots, blocking the permeation path of water molecules. The biodegradability of 1-ethyl-3-methylimidazolium acetate (Example 3) was 85.3%. The acetate group (CH3COO⁻) can mildly hydrolyze hemicellulose without producing toxic residues, but its degradation efficiency is lower than that of glycine due to the lack of nitrogen source supply. Its water contact angle is 36.2°, and the acetate group exposes the cellulose hydroxyl groups (-OH) through hydrogen bonds, significantly reducing surface energy and exhibiting optimal hydrophilicity. In contrast, the biodegradability of 1,1-butyl-3-methylimidazolium trifluoroacetate (Comparative Example 1) was 83.5%. The strongly hydrophobic fluorocarbon chain (-CF3) of the trifluoroacetate group (CF3COO⁻) hinders microbial attachment, and the CF bond is difficult to decompose. Its water contact angle is 48.3°, and the oriented arrangement of the -CF3 groups forms a low surface energy layer, significantly enhancing hydrophobicity. In summary, 1-allyl-3-methylimidazolium glycine achieves the best balance between biodegradability and hydrophilicity by providing a microbially available nitrogen source (-NH2) and hydrophilic groups (-COOH).

[0097] Under the same imidazole salt (1-allyl-3-methylimidazolium glycinate) conditions, ammonium fluoride (NH4HF2) achieved superior performance in both biodegradability (90.5%) and hydrophilicity (34.1°) due to its unique dual mechanism. The HF produced by its hydrolysis creates a slightly acidic environment, which not only catalyzes the rapid hydrolysis of hemicellulose but also activates the microbial community through the glycine anion as a nitrogen source. Simultaneously, it etches pores at the 5-10 μm level, significantly increasing the surface area for microbial attachment. Regarding hydrophilicity, HF2⁻ deeply etches the fibers, exposing more hydroxyl groups (-OH), which combine with the carboxyl groups (-COOH) of glycine to construct a hydrophilic network, significantly enhancing capillary action. In comparison, ammonium fluoride (NH4F) lacks acid catalysis and relies solely on fluoride ion desilication and glycine action, resulting in a lower degradation rate (88.2%) and hydrophilicity (38.5°). Ammonium fluoroborate (NH4BF4) exhibits a significantly lower degradation rate (82.1%) and hydrophilicity (43.8°) due to the inhibition of microbial enzyme activity by the boric acid produced from the decomposition of BF4⁻ and the blockage of pores on the fiber surface by adsorption. In contrast, the butyl long-chain residue of tetrabutylammonium fluoride (Comparative Example 2) forms a hydrophobic organic film, hindering microbial contact and water molecule penetration. Although its degradation rate (87.8%) is close to that of ammonium fluoride, its hydrophilicity (41.6°) is significantly deteriorated.

[0098] The optimal water contact angle (32.7°) in Example 6 is attributed to the synergistic effect of ammonium hydrofluoride and 1-ethyl-3-methylimidazolium acetate. Ammonium hydrofluoride deeply etches the bamboo fiber, forming hierarchical channels that promote hemicellulose hydrolysis and expose more hydroxyl groups. The acetate ions of 1-ethyl-3-methylimidazolium acetate bind to cellulose via hydrogen bonds, forming a dense hydrophilic network. Its small molecular weight and strong permeability significantly increase the surface hydroxyl exposure rate. The synergistic effect of these two components achieves rapid water penetration and enhanced wettability, making it the optimal solution for superhydrophilic materials.

[0099] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a fully biodegradable material based on bamboo fiber, characterized in that, The method is as follows: Step 1: Mix epoxidized soybean oil and kaolin with ultrasonic treatment to uniformly disperse and obtain a dispersion. Step 2: After crushing and dehydrating the bamboo fiber, add it to an aqueous solution of ammonium fluoride compound and imidazole salt, mix, heat and reflux, filter to collect the insoluble matter and wash, and dry to obtain modified bamboo fiber. Step 3: Mix modified bamboo fiber, dispersion, polylactic acid, calcium carbonate, vinyl bis-stearamide, glyceryl triacetate, and sorbitol to obtain a mixture; feed the mixture into a twin-screw extruder, control the temperature and extrusion process parameters, and cool and shape it through a vacuum die to obtain a fully biodegradable material; The ammonium fluoride compound is one of ammonium fluoride and ammonium hydrofluoride; The imidazole salt is one of 1-ethyl-3-methylimidazolium acetate and 1-allyl-3-methylimidazolium glycine.

2. The method for preparing a fully biodegradable material based on bamboo fiber as described in claim 1, characterized in that, The method is as follows, by weight: Step 1: Mix 1-3 parts of epoxidized soybean oil with 2-4 parts of kaolin and ultrasonically treat to uniformly disperse, thus obtaining a dispersion. Step 2: Crush 80-120 parts of bamboo fiber to 100-200 mesh and dehydrate; Add 20-30 parts of ammonium fluoride compound and 15-20 parts of imidazole salt to 500-1000 parts of water to obtain a mixed solution; add dehydrated bamboo fiber to the mixed solution and mix, then heat to reflux, then filter to collect insoluble matter and wash with water and ethanol 1-3 times each, then place in a constant temperature oven at 70-100℃ to dry for 5-24 hours to obtain modified bamboo fiber; Step 3: Mix the modified bamboo fiber prepared in Step 2, the dispersion prepared in Step 1, 20-40 parts of polylactic acid, 3-8 parts of calcium carbonate, 1-5 parts of vinyl bis-stearamide, 1-3 parts of glyceryl triacetate, and 2-8 parts of sorbitol. The mixing temperature is 100-140℃, the mixing speed is 300-800 rpm, and the time is 5-30 minutes to obtain a mixture. Put the mixture into a twin-screw extruder, control the temperature and extrusion process parameters, and cool and shape it through a vacuum die to obtain a fully biodegradable material.

3. The method for preparing a fully biodegradable material based on bamboo fiber as described in claim 1 or 2, characterized in that, In step 1, the ultrasonic time is 3-8 minutes, the ultrasonic power is 800-1200W, and the ultrasonic frequency is 20-60kHz.

4. The method for preparing a fully biodegradable material based on bamboo fiber as described in claim 1 or 2, characterized in that, The dehydration in step 2 involves stirring and dehydrating at 80-100℃ and 200-500 rpm until the moisture content is 1-3%.

5. The method for preparing a fully biodegradable material based on bamboo fiber as described in claim 1 or 2, characterized in that, In step 2, the heating and reflux process involves heating to 60-70℃ and refluxing for 1-3 hours.

6. The method for preparing a fully biodegradable material based on bamboo fiber as described in claim 1 or 2, characterized in that, In step 3, the temperature of the twin-screw extruder is controlled in 5 segments: 110-130℃, 130-150℃, 140-160℃, 150-170℃, and 140-160℃.

7. The method for preparing a fully biodegradable material based on bamboo fiber as described in claim 1 or 2, characterized in that, The extrusion process parameters of the twin-screw extruder in step 3 are: main machine speed: 20-30 rpm, material pressure: 1.5-2.5 MPa.

8. A fully biodegradable material based on bamboo fiber, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.