A corn stalk-based foam material and a preparation method and application thereof

Abstract

The application provides a corn straw-based foam material and a preparation method and application thereof. The foam material is prepared from the following raw materials in mass fractions: corn straw 2-30 parts, foam stabilizer 0.5-5 parts, foaming agent 0.01-2 parts, flocculating agent 0.1-2 parts and deionized water 50-150 parts. Through specific chemical and physical process treatment, the corn straw can be converted into a porous structure foam material. The foam material has the advantages of light weight, high strength and good heat insulation performance, and can be applied to the fields of heat insulation, heat preservation, packaging and filling materials. The application can effectively utilize the waste in agricultural production, reduce environmental pollution and provide a new type of environment-friendly material for the industrial field. The materials not only improve the added value of agricultural by-products, but also broaden the application range of the materials in the fields of building, packaging, filling materials and the like.

Description

A foam material based on corn stalks, its preparation method and application Technical Field

[0001] This invention relates to a foam material based on corn stalks, its preparation method and application, belonging to the field of environmental protection materials technology. Background Technology

[0002] Foam materials are lightweight, highly porous materials that can achieve certain specific performance indicators. They are characterized by being lightweight, permeable, highly porous, and having a large contact area, and are gradually becoming a hot topic in new materials research.

[0003] Corn stalks, a byproduct of agricultural production, are often discarded in large quantities, leading to resource waste and potential environmental problems. Traditional disposal methods, such as incineration or stockpiling, cause varying degrees of pollution. However, utilizing corn stalks to produce foam materials can effectively utilize agricultural waste while reducing environmental impact, thus holding significant importance for resource recycling and environmental protection. Currently, methods for converting corn stalks into foam materials, particularly lightweight, high-strength foam materials with good thermal insulation properties suitable for industrial applications, have not been widely reported.

[0004] Therefore, developing a high-performance foam material made from corn stalks through innovative processes has significant practical value and social significance. Summary of the Invention

[0005] To address the shortcomings of existing technologies and the need for agricultural waste treatment and resource utilization, this invention provides a foam material based on corn stalks, its preparation method, and its applications. Through specific chemical and physical processes, corn stalks can be transformed into a porous foam material. The foam material of this invention is lightweight, high-strength, and possesses excellent thermal insulation properties, making it applicable in fields such as thermal insulation, heat preservation, packaging, and filling materials. This invention effectively utilizes agricultural waste, reduces environmental pollution, and provides new environmentally friendly materials for the industrial sector. These materials not only increase the added value of agricultural by-products but also broaden their application scope in multiple fields such as construction, packaging, and filling materials.

[0006] The technical solution of the present invention is as follows:

[0007] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 2-30 parts corn stalks, 0.5-5 parts foam stabilizer, 0.01-2 parts foaming agent, 0.1-2 parts flocculant, and 50-150 parts deionized water.

[0008] According to a preferred embodiment of the present invention, the corn stalk-based foam material is prepared from the following raw materials in parts by weight: 5-15 parts corn stalk, 2-4 parts foam stabilizer, 0.01-0.10 parts foaming agent, 0.1-0.3 parts flocculant, and 100-150 parts deionized water.

[0009] Preferably, the corn stalk-based foam material is prepared from the following raw materials in parts by weight: 10 parts corn stalk, 2.5-3.25 parts foam stabilizer, 0.05-0.07 parts foaming agent, 0.15-0.2 parts flocculant, and 110-130 parts deionized water.

[0010] More preferably, the corn stalk-based foam material is prepared from the following raw materials in parts by weight: 10 parts corn stalk, 2.5-3.25 parts foam stabilizer, 0.05-0.07 parts foaming agent, 0.15 parts flocculant, and 120 parts deionized water.

[0011] Most preferably, the corn stalk-based foam material is prepared from the following raw materials in parts by weight: 10 parts corn stalk, 3.25 parts foam stabilizer, 0.07 parts foaming agent, 0.15 parts flocculant, and 120 parts deionized water.

[0012] According to a preferred embodiment of the present invention, the foam stabilizer is one or a combination of two or more of polyvinyl alcohol (PVA), calcium stearate, starch, or alkylolamide; preferably, the foam stabilizer is a combination of polyvinyl alcohol (PVA) and calcium stearate; the mass ratio of polyvinyl alcohol to calcium stearate is 1-1.6:1.

[0013] According to a preferred embodiment of the present invention, the foaming agent is one or a combination of two or more of sodium dodecyl sulfate (SDS), sodium α-alkenyl sulfonate, or hydrogen peroxide.

[0014] According to a preferred embodiment of the present invention, the flocculant is one or a combination of two or more of polyacrylamide, lignin sulfonate, polyaluminum chloride, or lithium carbonate.

[0015] The above-mentioned method for preparing corn stalk-based foam materials includes the following steps:

[0016] (1) Soak corn stalks in deionized water to remove dust and impurities; then grind them into pulp and balance the moisture to obtain straw pulp.

[0017] (2) Add the foam stabilizer to the straw slurry and stir to disperse it evenly; add the foaming agent and stir to foam; add the flocculant and stir to promote foaming and molding; add deionized water and stir to disperse it evenly; then dry to obtain the foam material based on corn straw.

[0018] According to a preferred embodiment of the present invention, in step (1), the soaking temperature is 45-55℃, the soaking time is 10-12 hours, and the soaking is sufficient to fully moisten the material. The amount of water used for soaking is only enough to submerge the straw.

[0019] According to a preferred embodiment of the present invention, in step (1), the grinding is mechanical grinding, which is performed using a disc mill; grinding is performed sequentially at disc mill gaps of 0.5 mm, 0.3 mm, and 0.1 mm, with a grinding time of 20-25 min at each gap, and the grinding environment temperature is room temperature.

[0020] According to the present invention, in step (1), balancing moisture means adding deionized water to the pulp obtained by grinding to obtain straw pulp of a specific concentration.

[0021] According to a preferred embodiment of the present invention, in step (1), the moisture content of the straw slurry is 70-80 wt%.

[0022] According to a preferred embodiment of the present invention, in step (2), before adding the foam stabilizer to the straw slurry, the step of stirring and dispersing the straw slurry is further included; the stirring rate is 200-400 r / min, the stirring time is 20-40 min, and the stirring temperature is room temperature.

[0023] According to a preferred embodiment of the present invention, in step (2), the stirring temperature after adding the foam stabilizer is room temperature, the stirring time is 5-15 min, the stirring rate is 300-400 r / min, and the system is stirred until it is a paste.

[0024] According to a preferred embodiment of the present invention, in step (2), the stirring temperature after adding the foaming agent is room temperature, the stirring rate is 400-600 r / min, and the stirring time is 10-25 min.

[0025] According to a preferred embodiment of the present invention, in step (2), the stirring temperature after adding the flocculant is room temperature, the stirring time is 5-10 min, and the stirring rate is 400-600 r / min.

[0026] According to a preferred embodiment of the present invention, in step (2), the stirring temperature after adding deionized water is room temperature, the stirring rate is 400-600 r / min, and the stirring time is 5-30 min, until the volume of the entire foaming system no longer changes.

[0027] According to a preferred embodiment of the present invention, in step (2), the drying is freeze drying.

[0028] The aforementioned applications of corn stalk-based foam materials are used in thermal insulation materials, heat preservation materials, or thermal insulation foam cushioning filling materials.

[0029] The technical features and beneficial effects of this invention are as follows:

[0030] 1. The corn stalk-based foam material of this invention uses inexpensive and readily available raw materials, and its preparation process is simple, efficient, and clean, requiring no complex experimental operations. In the preparation process of this invention, corn stalks are first used as raw materials. The stalks are treated by soaking at a specific temperature, which plays an auxiliary role in the subsequent pulping process. Then, a foam stabilizer is added to the system. After penetrating into the fiber interior, the foam stabilizer forms a preliminary foam base. The added foaming agent then foams under the action of the foam stabilizer, generating a mixture with a certain porosity, laying the foundation for the lightweight and thermal insulation properties of the foam material. Subsequently, the interaction between the flocculant and the foaming agent, along with an appropriate water content, jointly promotes the final formation of the foam material, ensuring its lightweight and highly efficient thermal insulation characteristics. Through the above process steps, the final corn stalk-based foam material has the characteristics of low density and high porosity, while ensuring the material's thermal insulation performance and structural stability.

[0031] 2. The foaming agent used in this invention plays a crucial role in the preparation of corn stalk-based foam materials. On the one hand, it significantly improves foaming efficiency, effectively reduces liquid interfacial tension, maintains stable structural properties, and has a wide applicable temperature, humidity, and pH range, ensuring the rapid formation and structural stability of the foam material. On the other hand, the foaming agent used in this invention is non-toxic, safe, and environmentally friendly; it does not produce toxic gases during the foaming process. In actual industrial production, this process not only improves production efficiency but also reduces potential hazards during large-scale industrial production and effectively lowers production costs.

[0032] The specific type and ratio of foaming agent used in this invention are designed specifically for corn stalk raw material systems, ensuring efficient reaction and excellent foam material performance. Changing the type or ratio of the foaming agent will prevent the acquisition of the lightweight, high-efficiency thermal insulation foam material described in this invention, and will also prevent the realization of the environmental protection and performance advantages expected by this invention. Therefore, the selection and use of the foaming agent is one of the key factors in achieving the technical features and beneficial effects of this invention.

[0033] 3. The raw materials of this invention are carefully proportioned and synergistically formulated, with a small amount of flocculant used to assist foaming. This foaming method utilizing composite additives achieves the desired foaming effect with less foaming agent and flocculant, improving production foaming efficiency and making it easier to form. By precisely controlling the amount of reagents used in the foaming process, it is possible to avoid poor results due to insufficient dosage, and also to prevent unnecessary production costs due to excessive use, thus achieving a dual optimization of cost-effectiveness and production efficiency.

[0034] 4. The specific composition of the corn stalk-based foam material in this invention ensures the unique performance and effects of the material. Only through the specific types and precise proportions of raw materials in this invention can the lightweight, high-efficiency thermal insulation properties of the foam material be achieved. For example, corn stalks, as the main raw material, possess unique chemical structures and physical properties that are key to achieving the low density and high porosity of the foam material. Furthermore, the addition of organic foam stabilizers not only provides the necessary chemical cross-linking for the material, enhancing its mechanical strength during molding, but also helps ensure its thermal insulation performance. Appropriate deionized water is crucial for achieving the material's excellent performance; insufficient water may lead to foaming failure, while excessive water may cause over-foaming, reducing the mechanical properties and stability of the foam material. Only when the raw materials interact in precise proportions can a foam material with the desired pore structure be effectively formed. The raw material composition of this invention, as a whole, achieves the expected effects of the foam material through the synergistic effect of each raw material.

[0035] 5. In the method for preparing the corn stalk-based foam material of the present invention, the foam stabilizer is added before the foaming agent. This order is crucial to ensuring the successful preparation and excellent performance of the material. If this order is changed, the lightweight and efficient thermal insulation foam material described in this invention cannot be obtained, nor can the expected physical properties and environmental characteristics be achieved. In each reaction step, the order of adding reagents and raw materials, as well as the types and ratios of foaming agents, foam stabilizers, and flocculants, are key factors affecting the quality of the final foam material.

[0036] Only by adding a foam stabilizer first can the straw pulp and other raw materials be encapsulated within the organic system of the foam stabilizer during the subsequent foaming reaction, allowing for more uniform dispersion of the slurry and the formation of a uniform and stable foam structure. If this step order is reversed, the uniform dispersion of the slurry and added reagents cannot be effectively achieved, thus affecting the final performance of the foam material. Therefore, the precise coordination of each step and condition in the preparation method of this invention is fundamental to achieving the excellent performance of the foam material. The foam material prepared by this method not only provides a new avenue for the reuse of agricultural waste but also has broad application prospects due to its excellent physical properties and environmental characteristics.

[0037] 6. The foam material of this invention exhibits stable cell structure, lightweight, and good mechanical stiffness (with a high Young's modulus) and thermal insulation properties, maintaining its performance under various environmental conditions. This makes it valuable for applications in building insulation, cold chain logistics, and other fields, and also allows it to be widely used as an excellent thermal insulation and buffer filling material in daily life. The thermal insulation properties of this foam material are particularly outstanding. Even with various raw material ratios, its thermal conductivity is as low as 0.0312 W / (m·K). According to national standards, materials with a thermal conductivity of no more than 0.12 W / (m·K) at an average temperature not exceeding 350℃ can be called thermal insulation materials; while materials with a thermal conductivity below 0.05 W / (m·K) are considered high-efficiency thermal insulation materials. This demonstrates that the foam material of this invention meets the stringent requirements for being an excellent thermal insulation material.

[0038] Furthermore, the foam material of this invention also exhibits excellent mechanical stiffness, and the resulting foam material has a high Young's modulus when prepared with several different raw material ratios. The foam material prepared with the preferred ratio of this invention has high resilience and cushioning performance, and a relatively robust structure. Therefore, the foam material of this invention can serve as an excellent thermal insulation and cushioning filling material, with great application potential in many aspects of daily life.

[0039] Furthermore, due to the natural properties of corn stalks, this foam material is biodegradable, which helps reduce environmental pollution and promotes sustainable development, making it an ideal packaging or insulation material.

[0040] Meanwhile, this invention effectively utilizes agricultural waste, reduces environmental pollution, and provides new environmentally friendly materials for the industrial sector; it also increases the added value of agricultural by-products and provides innovative solutions for the environmental treatment and resource utilization of agricultural waste, which has significant social and economic implications. Attached Figure Description

[0041] Figure 1 shows a top view (a) and a front view (b) of the foam material prepared in Example 1;

[0042] Figure 2 shows the thermal conductivity test results of the foam material prepared in Example 1;

[0043] Figure 3 shows the stress-strain curve of the foam material prepared in Example 1. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0045] In addition, the experimental methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0046] Example 1

[0047] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 10.0g corn stalks, 2.0g polyvinyl alcohol (polyvinyl alcohol 1750) (foam stabilizer), 1.25g calcium stearate (foam stabilizer), 0.07g foaming agent (sodium α-alkenyl sulfonate), 0.15g flocculant (lithium carbonate), and 120.0g deionized water.

[0048] The specific steps of the preparation method of the above-mentioned corn stalk-based foam material are as follows.

[0049] Step (1) Raw material preparation

[0050] Cut all the prepared corn stalks into short sections of about 5cm-6cm. Soak 1kg of corn stalk sections in warm water (50℃) for 12 hours. Soaking removes some dust and impurities, fully moistens the material, and prepares it for mechanical grinding.

[0051] Step (2) Pulping

[0052] Using a continuous high-concentration disc mill, the raw material obtained in step (I) was sequentially milled at room temperature in disc mill gaps of 0.5 mm, 0.3 mm, and 0.1 mm, with each disc mill gap being milled for 25 minutes. Deionized water was then added to balance the moisture content, resulting in straw slurry with a moisture content of 75 wt%.

[0053] Step (3) Foaming reaction

[0054] Add 40g of the straw slurry obtained in step (II), including 10g of corn straw, to a beaker and stir at room temperature for 30 minutes at a speed of 300 rpm to evenly disperse the slurry. Add a foam stabilizer, first adding 1.25g of powdered calcium stearate, and stir at room temperature for 5 minutes at 400 rpm to fully mix with the fiber slurry. Then add a polyvinyl alcohol aqueous solution (containing 2.0g of polyvinyl alcohol and 50g of deionized water), and stir at room temperature for 10 minutes at 400 rpm until a paste is formed. Add 0.07g of sodium α-olefin sulfonate as a foaming agent, and stir rapidly at room temperature for 20 minutes at 500 rpm. Next, add 0.15g of lithium carbonate as a flocculant, and stir at 500 rpm for 10 minutes at room temperature to promote foaming and molding. Finally, add 40g of deionized water for quantitative determination, with a total moisture content of 120g. Stir thoroughly at 500 rpm at room temperature for 20 minutes until the volume of the entire foaming system no longer changes. Record the foaming volume as 531 mL and end the foaming process.

[0055] Step (IV) Foam Molding

[0056] The composite straw slurry foam obtained in step (III) was quickly transferred to a metal cylindrical container with a movable bottom (50 mm in diameter and 40 mm in height), and the volume before drying was recorded. The container containing the foam was completely frozen and then placed in a vacuum refrigerated dryer for drying for 60 h. After drying was completed, the container was removed. The foam was removed from the container to obtain a foam sample, and the volume of the foam after drying was recorded.

[0057] Figure 1 shows the top view (a) and front view (b) of the foam material prepared in this embodiment. As can be seen from the figure, the foam material is regularly shaped and has a high porosity.

[0058] The thermal conductivity test diagram of the foam material prepared in this embodiment is shown in Figure 2. As can be seen from the figure, after the hot wire test, the foam material has a large temperature difference during the test time and has a small thermal conductivity, making it suitable for the preparation of thermal insulation materials.

[0059] The stress-strain curve of the foam material prepared in this embodiment is shown in Figure 3. Three samples were tested in parallel. As can be seen from the figure, the foam material has a small deformation under a pressure of 0.02 MPa, indicating that the foam material has high stiffness, that is, a high Young's modulus value.

[0060] Example 2

[0061] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 10.0g corn stalks, 1.25g polyvinyl alcohol (polyvinyl alcohol 1750) (foam stabilizer), 1.25g calcium stearate (foam stabilizer), 0.06g foaming agent (sodium α-alkenyl sulfonate), 0.15g flocculant (lithium carbonate), and 120.0g deionized water.

[0062] The above-mentioned method for preparing foam materials based on corn stalks uses the same amount of raw materials as above, and the remaining steps and conditions are the same as in Example 1.

[0063] Example 3

[0064] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 10.0g corn stalks, 1.25g polyvinyl alcohol (polyvinyl alcohol 1750) (foam stabilizer), 1.25g calcium stearate (foam stabilizer), 0.06g foaming agent (sodium α-alkenyl sulfonate), 0.15g flocculant (lithium carbonate), and 115.0g deionized water.

[0065] The above-mentioned method for preparing corn stalk-based foam materials includes the following steps:

[0066] Steps (i) and (ii) are the same as in Example 1;

[0067] Step (3) Foaming reaction

[0068] Add 40g of the straw slurry obtained in step (II) (containing 10g of corn straw) to a beaker and stir at room temperature for 30 minutes at a speed of 300 rpm to evenly disperse the slurry. Add a foam stabilizer, first adding 1.25g of powdered calcium stearate, and stir at room temperature for 5 minutes at 400 rpm to fully mix with the fiber slurry. Then add a polyvinyl alcohol aqueous solution (containing 1.25g of polyvinyl alcohol and 50g of deionized water as solvent), and stir at room temperature for 10 minutes at 400 rpm until a paste is formed. Add 0.06g of sodium α-olefin sulfonate as a foaming agent, and stir rapidly at room temperature for 20 minutes at 500 rpm. Next, add 0.15g of lithium carbonate as a flocculant, and stir at 500 rpm for 10 minutes at room temperature to promote foaming and molding. Finally, add 35g of deionized water for quantitative determination, with a total moisture content of 115g. Stir thoroughly at 500 rpm at room temperature for 20 minutes until the volume of the entire foaming system no longer changes, then stop foaming.

[0069] Step (iv) is the same as in Example 1.

[0070] Example 4

[0071] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 10.0g corn stalks, 1.25g polyvinyl alcohol (polyvinyl alcohol 1750) (foam stabilizer), 1.25g calcium stearate (foam stabilizer), 0.07g foaming agent (sodium α-alkenyl sulfonate), 0.20g flocculant (lithium carbonate), and 110.0g deionized water.

[0072] The above-mentioned method for preparing corn stalk-based foam materials includes the following steps:

[0073] Steps (i) and (ii) are the same as in Example 1;

[0074] Step (3) Foaming reaction

[0075] Add 40g of the straw slurry obtained in step (II) (containing 10g of corn straw) to a beaker and stir at room temperature for 30 minutes at a speed of 300 rpm to evenly disperse the slurry. Add a foam stabilizer, first adding 1.25g of powdered calcium stearate, and stir at room temperature for 5 minutes at 400 rpm to fully mix with the fiber slurry. Then add a polyvinyl alcohol aqueous solution (containing 1.25g of polyvinyl alcohol and 50g of deionized water as solvent), and stir at room temperature for 10 minutes at 400 rpm until a paste is formed. Add 0.07g of sodium α-olefin sulfonate as a foaming agent, and stir rapidly at room temperature for 20 minutes at 500 rpm. Next, add 0.2g of lithium carbonate as a flocculant, and stir at 500 rpm for 10 minutes at room temperature to promote foaming and molding. Finally, add 30g of deionized water for quantitative determination, with a total moisture content of 110g. Stir thoroughly at 500 rpm at room temperature for 20 minutes until the volume of the entire foaming system no longer changes, then stop foaming.

[0076] Step (iv) is the same as in Example 1.

[0077] Example 5

[0078] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 10.0g corn stalks, 1.25g polyvinyl alcohol (polyvinyl alcohol 1750) (foam stabilizer), 1.25g calcium stearate (foam stabilizer), 0.05g foaming agent (sodium α-alkenyl sulfonate), 0.15g flocculant (lithium carbonate), and 120.0g deionized water.

[0079] The above-mentioned method for preparing foam materials based on corn stalks uses the same amount of raw materials as above, and the remaining steps and conditions are the same as in Example 2.

[0080] Example 6

[0081] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 10.0g corn stalks, 1.50g polyvinyl alcohol (polyvinyl alcohol 1750) (foam stabilizer), 1.25g calcium stearate (foam stabilizer), 0.06g foaming agent (sodium α-alkenyl sulfonate), 0.15g flocculant (lithium carbonate), and 110.0g deionized water.

[0082] The above-mentioned method for preparing corn stalk-based foam materials includes the following steps:

[0083] Steps (i) and (ii) are the same as in Example 1;

[0084] Step (3) Foaming reaction

[0085] Add 40g of the straw slurry obtained in step (II) (containing 10g of corn straw) to a beaker and stir at room temperature for 30 minutes at a speed of 300 rpm to evenly disperse the slurry. Add a foam stabilizer, first adding 1.25g of powdered calcium stearate, and stir at room temperature for 5 minutes at 400 rpm to fully mix with the fiber slurry. Then add a polyvinyl alcohol aqueous solution (containing 1.5g of polyvinyl alcohol and 50g of deionized water as solvent), and stir at room temperature for 10 minutes at 400 rpm until a paste is formed. Add 0.06g of sodium α-olefin sulfonate as a foaming agent, and stir rapidly at room temperature for 20 minutes at 500 rpm. Next, add 0.15g of lithium carbonate as a flocculant, and stir at 500 rpm for 10 minutes at room temperature to promote foaming and molding. Finally, add 30g of deionized water for quantitative determination, with a total moisture content of 110g. Stir thoroughly at 500 rpm at room temperature for 20 minutes until the volume of the entire foaming system no longer changes, then stop foaming.

[0086] Step (iv) is the same as in Example 1.

[0087] Example 7

[0088] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 10.0g corn stalks, 2.00g polyvinyl alcohol (polyvinyl alcohol 1750) (foam stabilizer), 1.25g calcium stearate (foam stabilizer), 0.07g foaming agent (sodium α-alkenyl sulfonate), 0.15g flocculant (lithium carbonate), and 130.0g deionized water.

[0089] The above-mentioned method for preparing corn stalk-based foam materials includes the following steps:

[0090] Steps (i) and (ii) are the same as in Example 1;

[0091] Step (3) Foaming reaction

[0092] Add 40g of the straw slurry obtained in step (II) (containing 10g of corn straw) to a beaker and stir at room temperature for 30 minutes at a speed of 300 rpm to evenly disperse the slurry. Add a foam stabilizer, first adding 1.25g of powdered calcium stearate, and stir at room temperature for 5 minutes at 400 rpm to fully mix with the fiber slurry. Then add a polyvinyl alcohol aqueous solution (containing 2g of polyvinyl alcohol and 50g of deionized water as solvent), and stir at room temperature for 10 minutes at 400 rpm until a paste is formed. Add 0.07g of sodium α-olefin sulfonate as a foaming agent, and stir rapidly at room temperature for 20 minutes at 500 rpm. Next, add 0.15g of lithium carbonate as a flocculant, and stir at 500 rpm for 10 minutes at room temperature to promote foaming and molding. Finally, add 50g of deionized water for quantitative determination, with a total moisture content of 130g. Stir thoroughly at 500 rpm at room temperature for 20 minutes until the volume of the entire foaming system no longer changes, then stop foaming.

[0093] Step (iv) is the same as in Example 1.

[0094] Example 8

[0095] A foam material based on corn stalks is prepared from the following raw materials in parts by weight: 10.0g corn stalks, 2.00g polyvinyl alcohol (polyvinyl alcohol 1750) (foam stabilizer), 1.25g calcium stearate (foam stabilizer), 0.06g foaming agent (sodium α-alkenyl sulfonate), 0.15g flocculant (lithium carbonate), and 120.0g deionized water.

[0096] The above-mentioned method for preparing foam materials based on corn stalks uses the same amount of raw materials as above, and the remaining steps and conditions are the same as in Example 1.

[0097] Example 9

[0098] A foam material based on corn stalks, as described in Example 1, except that polyvinyl alcohol (PVA) is not added; the other raw material composition is the same as in Example 1.

[0099] The preparation method of the above-mentioned corn stalk-based foam material is the same as that described in Example 1, except that polyvinyl alcohol (PVA) is not added, that is, the polyvinyl alcohol aqueous solution is replaced with 50g of deionized water; other steps and conditions are the same as in Example 1.

[0100] Example 10

[0101] A foam material based on corn stalks, as described in Example 1, except that calcium stearate is not added; the other raw material composition is the same as in Example 1.

[0102] The preparation method of the above-mentioned corn stalk-based foam material is the same as that described in Example 1, except that calcium stearate is not added; other steps and conditions are the same as in Example 1.

[0103] Example 11

[0104] A foam material based on corn stalks, as described in Example 1, except that the foaming agent is replaced with 30wt% hydrogen peroxide; the other raw material composition is the same as in Example 1.

[0105] The preparation method of the above-mentioned corn stalk-based foam material is the same as that described in Example 1, except that the foaming agent is replaced with 30wt% hydrogen peroxide; the other steps and conditions are the same as in Example 1.

[0106] Example 12

[0107] A foam material based on corn stalks, as described in Example 1, except that the foaming agent is replaced with sodium dodecyl sulfate (SDS); the other raw material composition is the same as in Example 1.

[0108] The preparation method of the above-mentioned corn stalk-based foam material is the same as that described in Example 1, except that the foaming agent is replaced with sodium dodecyl sulfate (SDS); the other steps and conditions are the same as in Example 1.

[0109] Example 13

[0110] A foam material based on corn stalks, as described in Example 1, except that the foaming agent is replaced by a combination of sodium dodecyl sulfate (SDS) (0.03g) and sodium α-alkenyl sulfonate (0.04g); the composition of other raw materials is the same as in Example 1.

[0111] The preparation method of the above-mentioned corn stalk-based foam material is the same as that described in Example 1, except that the foaming agent is replaced by a combination of sodium dodecyl sulfate (SDS) and sodium α-alkenyl sulfonate; the other steps and conditions are the same as in Example 1.

[0112] Example 14

[0113] A foam material based on corn stalks, as described in Example 1, except that lithium carbonate is replaced with polyacrylamide; the other raw material composition is the same as in Example 1.

[0114] The preparation method of the above-mentioned corn stalk-based foam material is the same as that described in Example 1, except that lithium carbonate is replaced with polyacrylamide; other steps and conditions are the same as in Example 1.

[0115] Comparative Example 1

[0116] A foam material, as described in Example 1, except that polyvinyl alcohol and calcium stearate are not added; the composition of other raw materials is the same as in Example 1.

[0117] The foam preparation method described above is the same as that in Example 1, except that polyvinyl alcohol and calcium stearate are not added; other steps and conditions are the same as in Example 1.

[0118] Comparative Example 2

[0119] A foam material, with the same raw material composition as in Example 1.

[0120] The foam preparation method described above is the same as that in Example 1, except that the order of adding the foam stabilizer and the foaming agent is changed.

[0121] Specifically as follows:

[0122] Steps (I) and (II) are the same as in Example 1;

[0123] Step (3) Foaming reaction

[0124] Add 40g of the straw slurry obtained in step (II) (containing 10g of corn straw) to a beaker and stir at room temperature for 30 minutes at a speed of 300 rpm to evenly disperse the slurry. Add 0.07g of sodium α-olefin sulfonate as a foaming agent and stir rapidly at room temperature at 500 rpm for 20 minutes. Add a foam stabilizer, first adding 1.25g of powdered calcium stearate and stirring at room temperature at 400 rpm for 5 minutes, then adding a polyvinyl alcohol aqueous solution (containing 2.0g of polyvinyl alcohol in 50g of deionized water) and stirring at room temperature at 400 rpm for 10 minutes. Next, add 0.15g of lithium carbonate as a flocculant and stir at room temperature at 500 rpm for 10 minutes to promote foaming and molding. Finally, add 40g of deionized water for quantitative determination, resulting in a total moisture content of 120g. Stir thoroughly at 500 rpm at room temperature for 20 minutes until the volume of the entire foaming system no longer changes. Record the foaming volume as 503 mL and end the foaming process.

[0125] Step (iv) is the same as in Example 1.

[0126] Comparative Example 3

[0127] A foam material, as described in Example 1, except that lithium carbonate is not added; the other raw material composition is the same as in Example 1.

[0128] The foam preparation method described above is the same as that in Example 1, except that lithium carbonate is not added; the other steps and conditions are the same as in Example 1.

[0129] Ultimately, foaming failed, and no foam material was obtained. This demonstrates that lithium carbonate, as a flocculant, can promote foam formation. Without the addition of lithium carbonate, the foaming process would be much more difficult.

[0130] Test case

[0131] The foamed materials prepared in the examples and comparative examples were tested for foam volume, density, Young's modulus, and thermal conductivity. The test results are shown in Table 1.

[0132] Table 1

[0133]

[0134]

[0135] Based on the test results in Table 1, we can compare and analyze the Young's modulus and thermal conductivity of the foam materials in the examples. Young's modulus is an indicator of a material's elasticity, while thermal conductivity reflects its thermal conductivity. These two parameters are crucial for evaluating the performance of foam materials.

[0136] First, in all successful embodiments, the Young's modulus ranged from 0.012 MPa to 0.166 MPa. The Young's modulus of Example 1 was 0.162 MPa, Example 11 was 0.152 MPa, Example 12 was 0.166 MPa, Example 13 was 0.163 MPa, and Example 14 was 0.156 MPa. This indicates that the foam materials of these embodiments possess good elasticity.

[0137] Next, the thermal conductivity ranged from 0.0312 W / (m·K) to 0.0453 W / (m·K). The thermal conductivity of Example 1 was 0.0336 W / (m·K), Example 3 was 0.0312 W / (m·K), Example 5 was 0.0321 W / (m·K), Example 9 was 0.0331 W / (m·K), Example 10 was 0.0338 W / (m·K), and Example 13 was 0.0354 W / (m·K). These values ​​indicate that the foam materials of these examples have good thermal insulation properties.

[0138] Therefore, the foam material obtained by this invention has the advantages of being lightweight, highly elastic, and relatively strong, while its low thermal conductivity gives it good thermal insulation performance.

[0139] In the above embodiments, by comprehensively comparing the performance parameters of the materials such as Young's modulus and thermal conductivity, Embodiments 1 and 13 show better results. Preferably, Embodiment 1 has the best overall effect.

[0140] 1. The foam materials of Examples 1 and 13 showed good performance in terms of elasticity and thermal insulation.

[0141] 2. The Young's modulus and thermal conductivity of Example 1 are both at a high level, indicating that it has good thermal insulation performance while maintaining good elasticity.

[0142] Therefore, based on the above analysis, Example 1 exhibits the best overall performance due to its excellent balance between Young's modulus and thermal conductivity. This balance is crucial for the practical application of foam materials, as it most likely affects the material's durability and thermal management capabilities.

Claims

1. A foam material based on corn stalks, characterized in that, The material is prepared from the following raw materials in parts by weight: 10 parts corn stalks, 3.25 parts foam stabilizer, 0.07 parts foaming agent, 0.15 parts flocculant, and 120 parts deionized water; the foam stabilizer is a combination of polyvinyl alcohol (PVA) and calcium stearate; the mass ratio of polyvinyl alcohol to calcium stearate is 1.6:1; the foaming agent is sodium α-alkenyl sulfonate, or a combination of sodium dodecyl sulfate (SDS) and sodium α-alkenyl sulfonate; the flocculant is lithium carbonate; the preparation method of the corn stalk-based foam material includes the following steps: (1) soaking corn stalks in deionized water to remove dust and impurities; then grinding and balancing the moisture to obtain a straw slurry; (2) adding the foam stabilizer to the straw slurry and stirring to disperse it evenly; adding the foaming agent and stirring to foam; adding the flocculant and stirring to promote foaming and molding; adding deionized water and stirring to stir; and then drying to obtain the corn stalk-based foam material.

2. The foam material based on corn stalks according to claim 1, characterized in that, Step (1) includes one or more of the following conditions: i. The soaking temperature is 45-55℃, the soaking time is 10-12h, and the soaking is sufficient to wet the material; ii. The pulping is mechanical pulping, using a disc mill; the pulping is carried out sequentially at disc mill gaps of 0.5mm, 0.3mm, and 0.1mm, with a pulping time of 20-25min at each gap, and the pulping environment temperature is room temperature; iii. The moisture content of the straw pulp is 70-80wt%.

3. The foam material based on corn stalks according to claim 1, characterized in that, Step (2) includes one or more of the following conditions: i. Before adding the foam stabilizer to the straw slurry, the step of stirring and dispersing the straw slurry is also included; the stirring rate is 200-400 r / min, the stirring time is 20-40 min, and the stirring temperature is room temperature; ii. After adding the foam stabilizer, the stirring temperature is room temperature, the stirring time is 5-15 min, the stirring rate is 300-400 r / min, and the stirring is continued until the system is a paste; iii. After adding the foaming agent, the stirring temperature is room temperature, the stirring rate is 400-600 r / min, and the stirring time is 10-25 min; iv. After adding the flocculant, the stirring temperature is room temperature, the stirring time is 5-10 min, and the stirring rate is 400-600 r / min; v. After adding deionized water, the stirring temperature is room temperature, the stirring rate is 400-600 r / min, and the stirring time is 5-30 min, until the volume of the entire foaming system no longer changes; vi. Drying is freeze drying.

4. The application of the corn stalk-based foam material as described in any one of claims 1-3, characterized in that it is applied to thermal insulation materials, heat insulation materials, or thermal insulation foam cushioning filling materials.

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