Environment-friendly foam manufacturing method

Abstract

The invention relates to the technical field of environment-friendly foam, and discloses an environment-friendly foam manufacturing method. The preparation method comprises the following steps: S1, mixing microcrystalline cellulose with an interface orientation agent; s2, pre-drying the poly (butylene succinate) and the polylactic acid; s3, mixing the lignin coated cellulose nanocrystals and triethyl citrate into the pre-mixture; s4, putting the obtained mixture into a high-pressure kettle, and injecting liquid carbon dioxide; s5, keeping the temperature at 160-170 DEG C to achieve dissolution balance; s6, carrying out microwave treatment on the obtained foam body by using microwave heating equipment in sections; s7, mixing the sodium alginate microcapsules with lipase; and S8, carrying out cooling treatment by using circulating water with the temperature of 5 + / -5 DEG C. The lignin-coated cellulose nanocrystal is used as a reinforcing material, so that not only is the mechanical property of the foam improved, but also the durability of the foam is enhanced. The influence of external environmental factors can be effectively resisted, and the stability and reliability of the foam in the using process are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of environmentally friendly foam, and in particular to a method for manufacturing environmentally friendly foam. Background Art

[0002] Environmentally friendly foams are gaining increasing attention, particularly in the packaging and construction materials sectors. However, many existing foam materials still suffer from insufficient mechanical properties, poor durability, and slow environmental degradation. Traditional foam materials often rely on chemical blowing agents, which can cause a degree of environmental pollution and are susceptible to environmental influences in practical applications, leading to performance degradation.

[0003] Regarding the aforementioned technologies, the strength and toughness of foams often rely on a single polymer matrix, limiting overall performance. Many materials are prone to deformation under high loads, which directly impacts the foam's service life. Furthermore, while commonly used physical foaming methods can reduce the release of harmful substances, they often result in uneven cell distribution, impacting the foam's mechanical properties.

[0004] Furthermore, existing degradation technologies mostly rely on chemical methods. While these methods can accelerate the decomposition process, they often produce harmful byproducts, further polluting the environment. This is especially true when using synthetic enzymes or adding chemical catalysts, which not only increase production costs but also may negatively impact ecosystems.

[0005] Current smart biodegradable materials often lack durability and efficiency, making it difficult to ensure the release of active enzymes during the degradation process. Even though some biodegradable materials incorporate biological components such as enzymes, their controlled release mechanisms are suboptimal, failing to effectively guarantee degradation efficiency and environmental friendliness.

[0006] In terms of foaming technology, existing technologies typically use a single foaming agent, which results in a low foaming ratio and an uneven cell structure. During the foaming process, large voids are often generated, affecting the physical properties of the entire material. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for manufacturing environmentally friendly foam, which solves the problems of insufficient mechanical properties, durability and degradation efficiency of existing environmentally friendly foam.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: a method for manufacturing environmentally friendly foam, comprising the following steps; S1. Mixing microcrystalline cellulose with an interface directing agent, and adding enzymatic lignin, wherein the mass ratio of the enzymatic lignin to the microcrystalline cellulose is 1:3-1:10, to prepare lignin-coated cellulose nanocrystals; S2, pre-drying polybutylene succinate and polylactic acid, and mixing the polybutylene succinate and polylactic acid in a mass ratio of 60:40 to obtain a premix; S3, mixing the lignin-coated cellulose nanocrystals and triethyl citrate into the premix, and performing twin-screw blending at a temperature set in the range of 160-170°C; S4, placing the obtained mixture in an autoclave, injecting liquid carbon dioxide, and adding ethanol at the same time; S5. Maintaining the temperature at 160-170° C. to achieve dissolution equilibrium, and performing a gradient pressure reduction to form a foam; S6. performing microwave treatment on the obtained foam segments using a microwave heating device; S7, mixing sodium alginate microcapsules with lipase, impregnating the foam, and then hot-air curing at 50-60° C. for 20-30 minutes; S8. Cool the foam with circulating water at 5℃±5℃ for 5-10 minutes, and then cut, shape and surface treat the foam.

[0009] Preferably, the interface directing agent in step S1 is sodium dodecylbenzene sulfonate. Microcrystalline cellulose and sodium dodecylbenzene sulfonate are mixed at a mass ratio of 100:0.3. Cellulose nanocrystals coated with lignin are then formed into a high-performance foam material. This material improves overall mechanical properties while ensuring stability and reliability during use.

[0010] Preferably, the pre-drying temperature in step S2 is 75-85° C. and the duration is 5-7 hours.

[0011] Furthermore, the pre-blending step of polybutylene succinate and polylactic acid aims to combine the advantages of these two bio-based polymers to achieve better physical properties. Polybutylene succinate provides excellent flexibility, while polylactic acid improves the rigidity of the material.

[0012] Preferably, in step S3, the lignin-coated cellulose nanocrystals, triethyl citrate and the premix are mixed in a mass ratio of 1:0.1:3.5.

[0013] Furthermore, by combining microcrystalline cellulose, an interfacial directing agent, and enzymatically hydrolyzed lignin, they designed lignin-coated cellulose nanocrystals. The mechanism of this process is that the lignin coating not only enhances the dispersibility of the cellulose nanocrystals but also helps improve their interaction with the polymer matrix. This novel material structure effectively resists the influence of external environmental factors, ensuring the stable performance of the foam during use.

[0014] Preferably, in step S4, the pressure of the liquid carbon dioxide is 6.2-6.8 MPa, and the proportion of ethanol added is 5% to 10%.

[0015] Preferably, in step S5, the pressure is reduced at a rate of 0.3 MPa-0.7 MPa per second, from 6.0 MPa-8.0 MPa to 5.0 MPa-7.0 MPa, and maintained for 30-60 seconds, and then reduced to 3.0 MPa.

[0016] Furthermore, by using a synergistic foaming technique involving liquid carbon dioxide and ethanol, the foam's expansion ratio and structural uniformity were effectively improved. In this step, liquid carbon dioxide acts as a physical foaming agent, forming a foam structure under high pressure, while ethanol improves the foam's formation process and stability.

[0017] Preferably, in step S6, the frequency of the microwave heating equipment is set to 2.4-2.5 GHz, and the power is processed in sections of 300 W×30s, 150 W×40s, and 50 W×20s.

[0018] Preferably, the temperature of the microwave treatment in step S6 is 115-125° C., and is lowered to below 70-80° C. in the final stage.

[0019] Furthermore, precise temperature control allows for uniform heating of the foam, promoting modification and cross-linking reactions. The advantage of microwave heating is its rapid penetration into the foam, ensuring a more consistent internal structure. Temperature management throughout the entire process is crucial for material modification, ensuring the foam's strength, toughness, and shape stability.

[0020] Preferably, in step S7, the mass concentration of sodium alginate is 0.4-0.6 wt %, and the loading amount of lipase is 15-20%.

[0021] Furthermore, sodium alginate microcapsules were combined with lipase to form an intelligent controlled-release degradation system. This design enables the microcapsules to continuously release lipase under specific conditions, thereby achieving controlled-release degradation of the foam and ensuring that no harmful substances are released during the degradation process.

[0022] Preferably, argon is used for the surface treatment in step S8, the surface power is set to 80-120 W, and the treatment time is 1-3 minutes.

[0023] Furthermore, through cyclic cooling and surface treatment, the foam reaches an ideal solidification state, enhancing its surface properties and facilitating subsequent processing. This treatment process provides greater flexibility in the practical application of the foam, especially in applications requiring moisture and water resistance.

[0024] In summary, the present invention includes at least one of the following beneficial technical effects: 1. This invention utilizes lignin-coated cellulose nanocrystals as a reinforcing material, improving not only the mechanical properties of the foam but also its durability. This material structure effectively resists the effects of external environmental factors, ensuring the foam's stability and reliability during use, thereby expanding its applicability across various applications.

[0025] 2. By encapsulating lipase in sodium alginate microcapsules, the present invention enables controlled-release degradation of the foam, ensuring rapid decomposition under specific conditions. This mechanism produces no harmful substances, effectively reducing plastic pollution to the environment.

[0026] 3. By incorporating sodium alginate microcapsules into the foam to protect and control the release of lipase, the present invention significantly improves the foam's degradation rate and enzyme activity. The microcapsules continuously release lipase during the degradation process, ensuring higher degradation efficiency.

[0027] 4. This invention utilizes a synergistic foaming process involving liquid carbon dioxide and ethanol, resulting in a higher expansion ratio and more uniform cell structure for the eco-friendly foam. This optimized foaming structure not only enhances the material's lightweight properties but also improves its mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1 , the present invention is described in further detail.

[0030] The present invention provides an environmentally friendly foam manufacturing method. Example 1: 100 g of microcrystalline cellulose and 0.3 g of sodium dodecylbenzene sulfonate were mixed, and 650 g of enzymatically hydrolyzed lignin (mass ratio of 1:6.5) was added and mixed under stirring to obtain LCNC.

[0031] 600 g of polybutylene succinate (PBS) and 400 g of polylactic acid (PLA) were pre-dried at 80° C. for 6 hours.

[0032] The prepared LCNC (10 g, 3.5 wt %) was mixed with 1 g of triethyl citrate and then added to the premix in step 2. The mixture was twin-screw blended at a temperature of 165° C. and a rotation speed of 80 rpm for 5 minutes.

[0033] The mixture was placed in an autoclave and injected with liquid carbon dioxide (CO2) to set the pressure to 6.5 MPa, and 7.5% of ethanol was added at the same time.

[0034] The temperature was maintained at 165° C., and the pressure was reduced at a rate of 0.5 MPa per second from 6.0 MPa to 5.0 MPa, maintained for 30 seconds, and then reduced to 3.0 MPa.

[0035] The foam was subjected to microwave treatment using a microwave heating device with a frequency set to 2.45 GHz and a power divided into sections of 300 W×30 s, 150 W×40 s, and 50 W×20 s.

[0036] Sodium alginate microcapsules (mass concentration 0.5 wt %, lipase loading 18%) were mixed, impregnated into the foam, and then cured with hot air at 55° C. for 20 minutes.

[0037] The cooling treatment was carried out using circulating water at 5°C ± 5°C for 5 minutes, and then the foam was cut and formed, and the surface was treated with argon gas at a power of 100W for 2 minutes.

[0038] Example 2: 100 g of microcrystalline cellulose and 0.3 g of sodium dodecylbenzene sulfonate were mixed, and 300 g of enzymatic lignin was added (mass ratio of 1:3), and stirred evenly to obtain LCNC.

[0039] 600 g of polybutylene succinate (PBS) and 400 g of polylactic acid (PLA) were pre-dried at 75° C. for 5 hours.

[0040] The prepared LCNC (10 g, 3.5 wt %) was mixed with 0.5 g of triethyl citrate and then added into the premixture in step 2. The mixture was twin-screw blended at a temperature of 160° C. and a rotation speed of 70 rpm for 4 minutes.

[0041] The mixture was placed in an autoclave and injected with liquid carbon dioxide (CO2) to a pressure of 6.2 MPa, and 5% ethanol was added at the same time.

[0042] The temperature was maintained at 160° C., and the pressure was reduced at a rate of 0.5 MPa per second from 6.0 MPa to 5.0 MPa, maintained for 30 seconds, and then reduced to 3.0 MPa.

[0043] The foam was subjected to microwave treatment using a microwave heating device, with the frequency set to 2.40 GHz and the power divided into sections of 300 W×25 s, 150 W×35 s, and 50 W×15 s.

[0044] Sodium alginate microcapsules (mass concentration 0.4 wt %, lipase loading 15%) were mixed, impregnated into the foam, and then cured with hot air at 50° C. for 20 minutes.

[0045] The foam was cooled using circulating water at 5°C ± 5°C for 5 minutes, and then cut and shaped. The surface was treated with argon gas at a power of 80W for 1 minute.

[0046] Example 3; 100 g of microcrystalline cellulose and 0.3 g of sodium dodecylbenzene sulfonate were mixed, and 1000 g of enzymatic lignin was added (mass ratio of 1:10), and stirred evenly to obtain LCNC.

[0047] 600 g of polybutylene succinate (PBS) and 400 g of polylactic acid (PLA) were pre-dried at 85° C. for 7 hours.

[0048] The prepared LCNC (10 g, 3.5 wt %) was mixed with 1.5 g of triethyl citrate and then added into the premix in step 2. The mixture was twin-screw blended at a temperature of 170° C. and a rotation speed of 90 rpm for 6 minutes.

[0049] The mixture was placed in an autoclave and injected with liquid carbon dioxide (CO2) to a pressure of 6.8 MPa, and 10% ethanol was added at the same time.

[0050] The temperature was maintained at 170°C, and the pressure was reduced at a rate of 0.5 MPa per second from 6.0 MPa to 5.0 MPa, maintained for 30 seconds, and then reduced to 3.0 MPa.

[0051] The foam was subjected to microwave treatment using a microwave heating device, with the frequency set to 2.50 GHz and the power divided into sections of 300 W×35 s, 150 W×45 s, and 50 W×25 s.

[0052] Sodium alginate microcapsules (mass concentration 0.6 wt %, lipase loading 20%) were mixed, impregnated into the foam, and then cured with hot air at 60° C. for 30 minutes.

[0053] The foam was cooled using circulating water at 5°C ± 5°C for 5 minutes, and then cut and shaped. The surface was treated with argon gas at a power of 120W for 3 minutes.

[0054] Comparative Example 1: Compared with Example 1, the difference is that no lignin-coated cellulose nanocrystals are used, and the rest are the same.

[0055] Comparative Example 2: Compared with Example 1, the difference is that triethyl citrate is not added, and the rest are the same.

[0056] Comparative Example 3: Compared with Example 1, the difference is that traditional chemical foaming agents are used instead of liquid carbon dioxide and ethanol in the foaming process, and the rest are the same.

[0057] Comparative Example 4: Compared with Example 1, the difference is that no sodium alginate microcapsules and lipase are added, and only a simple curing treatment is performed. The rest are the same.

[0058] Experiment 1: Specific description of mechanical properties comparison experiment Purpose of the experiment The enhancement effect of lignin-coated cellulose nanocrystals (LCNC) on the mechanical properties of the foam was verified by comparing the tensile strength and compression resilience of Example 1 with that of Comparative Example 1.

[0059] Experimental Materials: The environmentally friendly foam prepared in Example 1; The environmentally friendly foam prepared in Comparative Example 1.

[0060] Experimental equipment: Tensile testing machine (ASTM D638); Compression testing machine (ASTM D3574); Precision electronic scales; Fixtures and test pieces.

[0061] Experimental procedures The environmentally friendly foams of Example 1 and Comparative Example 1 were respectively cut into standard test pieces with a size of 10 mm×100 mm×5 mm for tensile testing.

[0062] Similarly, compression test samples were cut to a size of 50 mm × 50 mm × 20 mm.

[0063] The tensile test piece was clamped into the tensile testing machine and the tensile rate was set to 50 mm / min.

[0064] The breaking strength, elongation and any observable failure mode of the material during tension were recorded.

[0065] Each group of samples (3 per group) was tested in duplicate to obtain an average value.

[0066] The compression test sample was placed in the compression testing machine, a uniform compression load was applied, and the compression speed was set to 5 mm / min.

[0067] Apply pressure until the sample height is reduced to 10 mm, maintain the pressure for 30 seconds, then unload and record the sample's recovered height.

[0068] Each group of samples (3 per group) was tested in duplicate to obtain an average value.

[0069] Data Records: Record data from all tests including load, failure mode, and recovery height.

[0070] The experimental data are shown in Table 1: Table 1 Mechanical properties comparison test results Summarize; Comparing the results of Experiment 1, we clearly see the significant improvement in the mechanical properties of the foam achieved by lignin-coated cellulose nanocrystals (LCNCs). This phenomenon is closely related to the material's mechanism. The composite system of LCNCs and microcrystalline cellulose not only enhances the interfacial interactions but also improves the dispersion of cellulose, resulting in a more uniform and stable microstructure within the polymer matrix. This improvement is particularly evident in the tensile and compressive properties, demonstrating that the introduction of LCNCs effectively enhances the mechanical properties of the foam.

[0071] In tensile tests, the foam of Example 1 exhibited high tensile strength and elongation, demonstrating that the LCNC coating enhances the tensile strength and toughness of cellulose. This process can be attributed to the effective lignin coating and the excellent integration of cellulose nanocrystals, forming a strong and resilient composite network. Compared with Comparative Example 1, the foam lacking LCNC not only exhibited reduced strength but also exhibited brittle fracture, fully demonstrating the important role of LCNC in improving the toughness and durability of the material.

[0072] Compression performance test results show that Example 1 exhibits superior compression resilience, demonstrating a higher recovery height and overall structural integrity. This phenomenon is closely related to the introduction of lignin, which improves the material's adhesion and elasticity, allowing the foam to better recover after compression. The sample in Comparative Example 1, on the other hand, exhibits a lower recovery height, indicating that the lack of LCNC makes it difficult for the foam to recover after deformation, resulting in permanent deformation.

[0073] Experiment 2: Specific description of degradation performance comparison experiment Purpose of the experiment; The promoting effect of triethyl citrate as a degradation trigger on the degradation performance of the material was verified by comparing the biodegradation rates of Example 1 and Comparative Example 2.

[0074] Experimental Materials: The environmentally friendly foam prepared in Example 1; The environmentally friendly foam prepared in Comparative Example 2.

[0075] Experimental equipment; Compost bins; Precision electronic scales; Temperature and humidity monitors; Sampler.

[0076] Experimental procedures; The environmentally friendly foams of Example 1 and Comparative Example 2 were cut into samples of the same size, 5 cm×5 cm×1 cm, respectively, to ensure that each sample had similar quality.

[0077] Add an appropriate amount of composting materials (such as grass clippings, straw, etc.) into the compost bin and maintain appropriate humidity (about 60%) and temperature (about 25-30°C) to simulate natural composting conditions.

[0078] Bury each sample evenly in the compost, ensuring there is ample space between each sample to allow for oxygen circulation.

[0079] Take samples every seven days and record changes in their mass and appearance. Use an electronic scale to measure the mass loss of the samples and record the data. Also observe for any obvious signs of degradation, such as color change or structural damage.

[0080] Record changes in sample quality and appearance at each time point, and continuously monitor the temperature and humidity of the compost bin to ensure consistent conditions.

[0081] After the experimental period (60 days), the degradation rate of each sample was calculated and the degradation performance was evaluated by comparing the percentage of mass loss.

[0082] The experimental data are shown in Table 2: Table 2 Degradation performance comparison test results Summarize; Comparing the results of Experiment 2, it is clear that triethyl citrate is effective in promoting foam degradation, especially in Example 1, where the degradation rate is significantly higher than that of Comparative Example 2. This difference in performance is closely related to the chemical structure and functional mechanism of triethyl citrate. As a bio-based degradation trigger, triethyl citrate can effectively reduce the interaction forces between polymer chains, making the foam more susceptible to microbial degradation under specific circumstances. Experiments have shown that adding such substances can accelerate the degradation process and improve the biocompatibility of the material in the natural environment.

[0083] Furthermore, experimental results showed that the foam in Example 1 exhibited significant mass loss and significant structural changes over 60 days, which is related to the mechanism of action of triethyl citrate. This compound promotes the hydrolysis and scission of polymer chains in the foam, forming smaller decomposition products that can be further utilized by microorganisms. This accelerated process facilitates rapid degradation of the material, reducing its environmental burden, and demonstrates the potential for sustainable development applications of environmentally friendly materials.

[0084] Experiment 3: Specific description of foaming structure comparison experiment Purpose of the experiment; The effect of the synergistic foaming of liquid carbon dioxide and ethanol on the cell uniformity and foaming efficiency was verified by comparing the cell structure and foaming ratio of Example 1 and Comparative Example 3.

[0085] Experimental materials; The environmentally friendly foam prepared in Example 1; The environmentally friendly foam prepared in Comparative Example 3.

[0086] Experimental equipment; Scanning electron microscopy (SEM); Foaming ratio measuring device; Precision electronic scales; thermometer; Hygrometer.

[0087] Experimental procedures The environmentally friendly foams of Example 1 and Comparative Example 3 were cut into samples of the same size, 5 cm×5 cm×5 cm, respectively, to ensure that the quality of each sample was consistent.

[0088] The initial mass of each foam sample was recorded.

[0089] Use a thermometer and hygrometer to accurately measure the temperature and humidity of the surrounding environment to ensure uniform experimental conditions.

[0090] Calculate the expansion ratio, which is the ratio of the volume of the foam after foaming to the initial volume, and measure its volume by comparing the foam after foaming.

[0091] After the sample was dried, the surface and cross section of the foam were observed using a scanning electron microscope to record the morphology, distribution and size uniformity of the pores.

[0092] Observation results: Record the number and diameter of cells of each sample at different magnifications.

[0093] The volume change of each sample was recorded, the expansion ratio was calculated, and the characteristics of the cells were described.

[0094] Note that the specific appearance of the cells observed, including their size, shape, and uniformity of distribution, was recorded.

[0095] After the experiment is completed, the expansion ratio and cell structure results are sorted and counted. The experimental data are shown in Table 3: Table 3 Foaming structure comparison test results Summarize; The results of Experiment 3 clearly demonstrate that the synergistic foaming mechanism of liquid carbon dioxide and ethanol significantly improves the expansion ratio and cell uniformity of the eco-friendly foam. This phenomenon can be attributed to the efficient gas diffusion effect provided by liquid carbon dioxide during the foaming process. Its rapid vaporization at high temperatures produces a large number of bubbles, while the addition of ethanol effectively reduces the surface tension of the foaming liquid, promoting the formation and stability of bubbles. The successful application of this composite foaming technology results in a more uniform foam structure, thereby improving the material's mechanical properties and expanding its application areas.

[0096] The resulting pore structure in Example 1 exhibits high uniformity and moderate pore size, which is closely related to the aforementioned foaming mechanism. Liquid carbon dioxide, as a blowing agent, forms small, stable bubbles under high pressure, while ethanol optimizes the bubble formation process, resulting in more coordinated interactions between bubbles and ultimately forming a well-defined pore morphology. This mechanism effectively avoids the large voids and uneven bubble formation associated with traditional chemical blowing agents, thereby ensuring the reliability and strength of the foam during use.

[0097] Finally, analysis of experimental data further validated the positive role this foaming mechanism plays in the design and development of eco-friendly materials. By using a composite foaming method of liquid carbon dioxide and ethanol, not only was the foaming performance of the eco-friendly foam enhanced, but its physical properties, such as light weight, high strength, and excellent stress absorption, were also improved.

[0098] Experiment 4: Specific description of the intelligent degradation trigger comparison experiment Purpose of the experiment; The effectiveness of sodium alginate microcapsules in protecting lipase activity and triggering degradation was verified by comparing the degradation rate and enzyme activity of Example 1 with that of Comparative Example 4.

[0099] Experimental materials; The environmentally friendly foam prepared in Example 1; The environmentally friendly foam prepared in Comparative Example 4; Lipase solution.

[0100] Experimental equipment; mixer; Temperature controlled constant temperature water bath Spectrophotometer; Precision electronic scales; Sampler.

[0101] Experimental procedures; The environmentally friendly foams of Example 1 and Comparative Example 4 were cut into samples of the same size, 5 cm×5 cm×1 cm, respectively, to ensure that the quality of each sample was consistent.

[0102] Prepare an appropriate amount of lipase solution, adjust its concentration to 1% (v / v), and use a spectrophotometer set at a wavelength of 405 nm.

[0103] The lipase solution was heated to 37°C in a constant temperature water bath to maintain the enzyme activity at the optimal state.

[0104] In two different reaction bottles, the foam samples of Example 1 and Comparative Example 4 were placed respectively to ensure that the samples were evenly distributed.

[0105] Add lipase solution of determined concentration into each reaction bottle one by one, and record the reaction start time.

[0106] Samples were taken every 24 hours, and the degradation rate of the samples was measured using a spectrophotometer. The degree of degradation was evaluated by recording the changes in light absorbance.

[0107] At the same time, weigh the sample and record the change in mass, and observe the changes in the appearance of the sample.

[0108] Record mass loss, absorbance changes, and sample appearance at each time point to ensure data accuracy and consistency.

[0109] After the experimental period (48 hours), the mass loss and light absorbance of each sample were counted to evaluate the degradation effect and lipase activity of each sample.

[0110] The experimental data are shown in Table 4: Table 4 Comparative experimental results of intelligent degradation triggering Summarize; The results of Experiment 4 demonstrate that sodium alginate microcapsules play a significant role in enhancing lipase activity and increasing the foam degradation rate. This phenomenon can be explained by their unique mechanism. As a bio-based material, sodium alginate exhibits excellent biocompatibility and biodegradability. Its microcapsule structure not only effectively encapsulates and protects lipase but also allows for controlled release of the enzyme under specific conditions, thereby increasing its availability during the degradation process. This protective mechanism ensures that the lipase remains active throughout the reaction, thereby accelerating the foam degradation reaction.

[0111] During the degradation process, the sodium alginate microcapsules facilitate more complete lipase contact with the foam material, improving degradation efficiency. This mechanism involves the affinity between the enzyme and the substrate, as well as the gradual dissolution of the microcapsules, which facilitates enzyme release. Over time, the microcapsules gradually rupture, releasing the lipase that rapidly acts on the foam's polymer chains, breaking them down and converting them into small molecules that can be utilized by microorganisms, further accelerating the degradation process. This dynamic release mechanism not only increases the degradation rate but also enhances the consistency of degradation, ensuring rapid decomposition of the foam in the environment.

[0112] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing environmentally friendly foam, characterized in that: The following steps are included: S1. Mixing microcrystalline cellulose with an interface directing agent, and adding enzymatic lignin, wherein the mass ratio of the enzymatic lignin to the microcrystalline cellulose is 1:3-1:10, to prepare lignin-coated cellulose nanocrystals; S2, pre-drying polybutylene succinate and polylactic acid, and mixing the polybutylene succinate and polylactic acid in a mass ratio of 60:40 to obtain a premix; S3, mixing the lignin-coated cellulose nanocrystals and triethyl citrate into the premix, and performing twin-screw blending at a temperature set in the range of 160-170°C; S4, placing the obtained mixture in an autoclave, injecting liquid carbon dioxide, and adding ethanol at the same time; S5. Maintain the temperature at 160-170° C. to achieve dissolution equilibrium, and perform a gradient pressure reduction to form a foam; S6. performing microwave treatment on the obtained foam segments using a microwave heating device; S7, mixing sodium alginate microcapsules with lipase, impregnating the foam, and then hot-air curing at 50-60° C. for 20-30 minutes; S8. Cool the foam with circulating water at 5℃±5℃ for 5-10 minutes, and then cut, shape and surface treat the foam.

2. The method for manufacturing an environmentally friendly foam according to claim 1, characterized in that: In step S1, the interface directing agent is sodium dodecylbenzenesulfonate, and microcrystalline cellulose and sodium dodecylbenzenesulfonate are mixed in a mass ratio of 100:0.

3.

3. The method for manufacturing an environmentally friendly foam according to claim 1, characterized in that: The pre-drying temperature in step S2 is 75-85° C. and the duration is 5-7 hours.

4. The method for manufacturing an environmentally friendly foam according to claim 1, characterized in that: In step S3, the lignin-coated cellulose nanocrystals, triethyl citrate and the premix are mixed in a mass ratio of 1:0.1:3.

5.

5. The method for manufacturing environmentally friendly foam according to claim 1, characterized in that: In step S4, the pressure of the liquid carbon dioxide is 6.2-6.8 MPa, and the proportion of ethanol added is 5%-10%.

6. The method for manufacturing environmentally friendly foam according to claim 1, characterized in that: In step S5, the pressure is reduced at a rate of 0.3 MPa to 0.7 MPa per second, from 6.0 MPa to 8.0 MPa to 5.0 MPa to 7.0 MPa, and maintained for 30 to 60 seconds, and then reduced to 3.0 MPa.

7. The method for manufacturing environmentally friendly foam according to claim 1, characterized in that: In step S6, the frequency of the microwave heating equipment is set to 2.4-2.5 GHz, and the power is processed in sections of 300 W×30 s, 150 W×40 s, and 50 W×20 s.

8. The method for manufacturing environmentally friendly foam according to claim 1, characterized in that: The temperature of the microwave treatment in step S6 is 115-125° C., and is lowered to below 70-80° C. in the final stage.

9. The method for manufacturing environmentally friendly foam according to claim 1, characterized in that: In step S7, the mass concentration of sodium alginate is 0.4-0.6 wt %, and the loading amount of lipase is 15-20%.

10. The environmentally friendly foam manufacturing method according to claim 1, characterized in that: In step S8, argon gas is used for the surface treatment, the surface power is set to 80-120 W, and the treatment time is 1-3 minutes.

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