Epoxy resin-based corn stalk composite board and preparation method thereof

Abstract

The application discloses an epoxy resin-based corn straw composite board and a preparation method thereof, and belongs to the technical field of biomass materials and composite materials. The method comprises the following steps: crushing corn straw, and screening to obtain corn straw powder with a fiber length; mixing the corn straw powder and epoxy resin powder according to a mass ratio to obtain mixed raw materials; and placing the mixed raw materials under a preset temperature and pressure, and performing heat preservation and pressure preservation treatment for at least 2 hours, and then demolding to obtain the epoxy resin-based corn straw composite board. The hydrogen bond network formed by cellulose, hemicellulose and lignin in the corn straw under high temperature and high pressure and the bonding effect of the epoxy resin form a synergistic reinforcing effect, without the need for complex pretreatment such as separation of the corn straw skin and pulp, enzyme etching or nano-cellulose impregnation, the whole preparation process does not add formaldehyde-containing adhesives, no formaldehyde and other organic volatile substances are released, and the specific process is simple, the mechanical properties are excellent, and the process is green and environmentally-friendly.

Description

Technical Field

[0001] This invention relates to the field of biomass materials and composite materials technology, and more specifically to an epoxy resin-based corn stalk composite board and its preparation method. Background Technology

[0002] Corn stalks, as an important biomass resource, have an annual output of 330 million tons in my country, with a collectable amount of approximately 299 million tons. Developing efficient and environmentally friendly technologies for the comprehensive utilization of corn stalks has significant scientific value and practical implications. Currently, the main utilization pathways for corn stalks include returning them to the field, using them as feed, and processing them into raw materials. Their chemical composition is mainly cellulose, hemicellulose, and lignin. Under high temperature and pressure conditions, lignin in corn stalks can form a hydrogen bond network with fibers, cellulose can further strengthen this structure, and hemicellulose can be thermosetting into a thermosetting resin with adhesive properties. These characteristics provide a theoretical basis for the utilization of corn stalks in the production of boards.

[0003] Currently, several methods for preparing corn stalk engineered wood products have been proposed. For example, patent CN111300565A discloses a method for manufacturing anti-corrosion corn stalk recombinant material, using resorcinol-modified phenolic resin as an adhesive. Although this method can effectively improve the mechanical properties of the board, it releases formaldehyde and other volatile organic compounds during use, posing potential hazards to the environment and human health. Another patent, CN113084960A, proposes a process for preparing corn stalk boards without adhesives. This process achieves bonding by enzymatically etching the surface of the stalks and combining it with nanocellulose impregnation. However, this process is complex, time-consuming, and costly, making it difficult to scale up production. In addition, patent CN119116086A introduces a technology for preparing epoxy resin-based corn stalk composite boards based on physical methods. After crushing and sieving the corn stalks, they are directly subjected to high-temperature and high-pressure treatment. The hydrogen bond network formed by the stalk components during hot pressing and the internal bonding effect are used to form the board. Although this method has the advantages of no chemical additives and no formaldehyde release, the mechanical properties of the resulting boards are still not ideal.

[0004] In summary, existing corn stalk boards still have significant shortcomings in terms of the environmental friendliness of adhesives, process feasibility, and overall performance. Therefore, developing a corn stalk composite material that combines excellent mechanical properties, environmental friendliness, and ease of processing has become an important direction for development in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an epoxy resin-based corn stalk composite board and its preparation method, which can solve at least one of the aforementioned technical problems. The specific solution is as follows: This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Crush the corn stalks and sieve them to obtain corn stalk powder with a fiber length of 2-3 mm; S2. The corn stalk powder and epoxy resin powder with a particle size of 500 mesh are mixed at a mass ratio of 8:2 or 7:3 to obtain a mixed raw material; S3. The mixed raw materials are placed under a temperature of 140-160℃ and a pressure of 10-90MPa for heat preservation and pressure treatment for at least 2 hours. After that, the material is demolded to obtain the epoxy resin-based corn stalk composite board.

[0006] Furthermore, in S1, the corn stalks are cut into small pieces and then crushed as a whole without separating the skin and pulp.

[0007] Furthermore, in S2, the corn stalk powder and the epoxy resin powder are mixed evenly by mechanical stirring or manual shaking.

[0008] This invention also provides an epoxy resin-based corn stalk composite board, which is prepared using the same method as the epoxy resin-based corn stalk composite board.

[0009] Compared with the prior art, the above-described solutions of the present invention have at least the following beneficial effects: 1. The present invention relates to an epoxy resin-based corn stalk composite board and its preparation method. The method involves mixing corn stalk powder and epoxy resin powder and then hot-pressing them. The hydrogen bond network formed by cellulose, hemicellulose and lignin in corn stalks under high temperature and pressure, along with the bonding effect of epoxy resin, creates a synergistic reinforcing effect. Without the need for complex pretreatment such as peel and pulp separation, enzyme etching or nanocellulose impregnation of corn stalks, the tensile strength and flexural strength of the resulting composite board meet international standards, thus obtaining a green and environmentally friendly corn stalk composite board.

[0010] 2. The present invention discloses an epoxy resin-based corn stalk composite board and its preparation method, which uses epoxy resin powder as the sole adhesive. The entire preparation process includes only three physical steps: crushing, mixing, and hot pressing. No formaldehyde-containing adhesives such as resorcinol-modified phenolic resin are added, and no preservative impregnation treatment is performed. No formaldehyde or other volatile organic compounds are released during production and use. Compared with the existing technology of using resorcinol-modified phenolic resin adhesives, the present invention simplifies the preparation process and achieves environmental friendliness while ensuring the mechanical properties of the board. Attached Figure Description

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic diagram of the process flow for preparing an epoxy resin-based corn stalk composite board according to an embodiment of the present invention.

[0012] Figure 2 This is a schematic diagram illustrating the preparation process of an epoxy resin-based corn stalk composite board provided in an embodiment of the present invention.

[0013] Figure 3 This is a schematic diagram illustrating the bending strength of epoxy resin-based corn stalk composite boards under different raw material ratios and pressure conditions, as provided in embodiments of the present invention.

[0014] Figure 4 This is a schematic diagram illustrating the tensile strength of epoxy resin-based corn stalk composite boards under different raw material ratios and pressure conditions, as provided in embodiments of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0016] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the product or device that includes that element.

[0017] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] This invention provides a method for preparing an epoxy resin-based corn stalk composite board, as illustrated in the following flowchart: Figure 1 and Figure 2 As shown.

[0019] In this embodiment of the invention, a method for preparing an epoxy resin-based corn stalk composite board includes: S1. Crush the corn stalks and sieve them to obtain corn stalk powder with a fiber length of 2-3 mm.

[0020] Corn stalks are cut into 50cm pieces without separating the husks and pith, and then placed whole into a stalk shredder for 10 minutes. In this embodiment, the corn stalks are cut into 50cm pieces for easier shredding. The cutting length and subsequent shredding time can be adjusted according to the shredder used in actual application; this embodiment does not limit this. The method provided by this invention does not separate the husks and pith from the corn stalks, which not only simplifies the processing time of raw materials for preparing epoxy resin-based corn stalk composite boards, but also makes the operation simpler and more convenient, saving both time and economic costs.

[0021] Corn stalks are crushed, and in this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3 mm is screened to be used as the raw material for preparing epoxy resin-based corn stalk composite boards. The instrument used in this embodiment of the invention is selected with a fiber length of 2-3 mm. In actual applications, if a hydraulic press or other instruments are used, corn stalk powder with a length of 1-5 mm can be selected for processing and molding, depending on the actual situation. This embodiment of the invention does not impose any limitations on this.

[0022] S2. The corn stalk powder and epoxy resin powder with a particle size of 500 mesh are mixed at a mass ratio of 8:2 or 7:3 to obtain a mixed raw material.

[0023] Epoxy resin powder was mixed with corn stalk powder at two ratios of 20% and 30%, respectively. The particle size of the epoxy resin powder was 500 mesh. After weighing the corn stalk powder and epoxy resin powder according to the above ratio, they were placed in a plastic bag and shaken by hand for 10 minutes to ensure that the two materials were thoroughly mixed to obtain the mixed raw material.

[0024] This invention provides a preferred embodiment in which epoxy resin powder with a particle size of 500 mesh is mixed with corn stalk powder of 2-3 mm. Larger epoxy resin particles require grinding. In this embodiment, the corn stalk powder and epoxy resin powder are mixed at a mass ratio of 8:2 or 7:3. When the epoxy resin content is higher, the prepared composite board is more viscous overall.

[0025] In this embodiment of the invention, the mixed corn stalks and epoxy resin powder are used as raw materials for epoxy resin-based corn stalk composite boards. Only mixed corn stalks and epoxy resin powder of uniform specifications and proportions are needed. There is no need to use raw materials with different fiber lengths and different chemical ratios for mixing. No additional cooking treatment or grinding of raw materials is required. No additional biomass fiber is needed. Most importantly, no chemical reagents are used for treatment. The process is short, the equipment requirements are simple, and there is no risk of environmental pollution.

[0026] S3. The mixed raw materials are placed under a temperature of 140-160℃ and a pressure of 10-90MPa for heat preservation and pressure treatment for at least 2 hours. After that, the material is demolded to obtain the epoxy resin-based corn stalk composite board.

[0027] Corn stalk powder mixed with epoxy resin is used as raw material and placed into a small tablet press. The preset conditions in this embodiment are: applied pressure of 10-90 MPa, applied temperature range of 150°C, and holding time of 2 hours. Demolding completes the preparation of epoxy resin-based corn stalk composite boards. Existing board molding and pressing techniques typically require pretreatment of raw materials, such as chemical processing and cooking, to obtain corn stalk boards that meet international standards. In this embodiment, by precisely controlling the applied pressure, temperature, and holding time, the formation of hydrogen bonds and internal bonding effects in the cellulose, hemicellulose, and lignin of corn stalks are enhanced. By incorporating inexpensive epoxy resin and performing simple pretreatment of the raw materials, corn stalk boards with flexural and tensile strengths meeting international standards can be prepared. In this embodiment, the holding time is 2 hours; boards prepared with a holding time longer than 2 hours have the same strength as those prepared with a holding time of 2 hours.

[0028] This invention provides a preferred embodiment where the application temperature is 150°C. Corn stalk powder is mainly composed of cellulose, hemicellulose, and lignin, with hemicellulose being the most unstable and decomposing rapidly starting at 180°C. Lower temperatures result in poor mechanical properties of the board, while higher temperatures cause carbonization; therefore, an application temperature of 150°C is chosen.

[0029] In the embodiments of the present invention, the epoxy resin-based corn stalk composite boards are all prepared in a bending mold. The bending strength can be directly measured, and the tensile strength is tested by cutting the boards into dumbbell shapes using a laser cutting method.

[0030] In practical applications, instruments can be used to prepare whole epoxy resin-based corn stalk composite boards, and then the epoxy resin-based corn stalk composite boards for which the bending strength and tensile strength need to be tested can be cut. The embodiments of the present invention are for the convenience of testing, and the embodiments of the present invention do not limit this.

[0031] In this embodiment of the invention, the bending strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested in accordance with JIS A 5905:2003.

[0032] The following are several embodiments of the preparation method of the epoxy resin-based corn stalk composite board of the present invention. In the embodiments of the present invention, a 30-ton HY-30 press is used, molds are customized according to the JIS A 5905:2003 standard for testing flexural and tensile strength, and a heating jacket is used to heat the raw materials.

[0033] Example 1

[0034] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0035] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a ratio of 8:2. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are thoroughly mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0036] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 14.8 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0037] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 2.71g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.04g.

[0038] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 26.4 MPa and a tensile strength of 15.1 MPa.

[0039] Example 2

[0040] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0041] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a ratio of 8:2. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0042] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 25.9 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0043] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 2.54g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.10g.

[0044] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 34.7 MPa and a tensile strength of 21.2 MPa.

[0045] Example 3

[0046] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0047] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a ratio of 8:2. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0048] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 37.0 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0049] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 2.77g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.18g.

[0050] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 32.5 MPa and a tensile strength of 23.0 MPa.

[0051] Example 4

[0052] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0053] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a ratio of 8:2. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0054] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 48.0 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0055] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 3.61g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.13g.

[0056] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 31.3 MPa and a tensile strength of 21.0 MPa.

[0057] Example 5

[0058] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0059] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a ratio of 8:2. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0060] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 59.1 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0061] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 3.07g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.10g.

[0062] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 35.2 MPa and a tensile strength of 23.8 MPa.

[0063] Example 6

[0064] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0065] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a ratio of 8:2. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0066] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 70.2 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0067] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 3.16g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.12g.

[0068] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 28.8 MPa and a tensile strength of 20.0 MPa.

[0069] Example 7

[0070] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0071] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a ratio of 8:2. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0072] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 81.3 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0073] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 3.10g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.17g.

[0074] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 35.8 MPa and a tensile strength of 17.8 MPa.

[0075] Example 8

[0076] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0077] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a 7:3 ratio. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0078] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 14.8 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0079] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 3.04g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.12g.

[0080] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 41.0 MPa and a tensile strength of 18.0 MPa.

[0081] Example 9

[0082] This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0083] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a 7:3 ratio. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0084] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 25.9 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0085] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 3.68g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.11g.

[0086] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 40.9 MPa and a tensile strength of 23.2 MPa.

[0087] Example 10 This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0088] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a 7:3 ratio. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0089] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 37.0 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0090] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 2.65g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.04g.

[0091] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 44.6 MPa and a tensile strength of 25.0 MPa.

[0092] Example 11 This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0093] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a 7:3 ratio. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0094] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 48.0 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0095] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 3.63g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.12g.

[0096] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 44.2 MPa and a tensile strength of 23.0 MPa.

[0097] Example 12 This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0098] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a 7:3 ratio. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0099] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 59.1 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0100] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 2.77g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.07g.

[0101] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 43.6 MPa and a tensile strength of 21.8 MPa.

[0102] Example 13 This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0103] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a 7:3 ratio. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0104] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 70.3 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0105] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 2.73g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.14g.

[0106] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 38.8 MPa and a tensile strength of 24.8 MPa.

[0107] Example 14 This invention provides an epoxy resin-based corn stalk composite board and its preparation method, comprising the following steps: S1. Cut the corn stalks into 50cm sections without separating the husks and pith, and place them whole into a stalk crusher for crushing for 10 minutes. In this embodiment of the invention, corn stalk powder with a preset fiber length of 2-3mm is selected as the raw material for preparing epoxy resin-based corn stalk composite boards.

[0108] S2. Mix corn stalk powder with a fiber length of 2-3 mm and epoxy resin powder with a particle size of 500 mesh in a 7:3 ratio. Place the two powders in a sealed plastic bag and shake by hand for 10 minutes to ensure that the two materials are fully mixed and homogeneous. This mixture will serve as the raw material for preparing corn stalk composite boards.

[0109] S3. The two mixed powders are used as raw materials and placed into two custom molds for testing bending strength and tensile strength, respectively. They are then placed in a 30-ton HY-30 press for pressure application and heated by a heating jacket. The preset conditions in this embodiment are: applied pressure of 81.3 MPa, applied temperature of 150°C, and pressure and temperature holding time of 2 hours. Demolding completes the preparation of the epoxy resin-based corn stalk composite board.

[0110] In the embodiments of this invention, the epoxy resin-based corn stalk composite boards were all prepared in a bending mold. The bending strength could be measured directly after demolding, with a mass of 3.03g. The tensile strength was tested after demolding by laser-cutting the board into dumbbell shapes, with a mass of 1.11g.

[0111] In this embodiment of the invention, the flexural strength and tensile strength of the prepared epoxy resin-based corn stalk composite board were tested according to JIS A 5905:2003. The tested results showed a flexural strength of 36.0 MPa and a tensile strength of 22.8 MPa.

[0112] The data in the embodiments of the present invention are shown in Table 1 below: Table 1 Data of the Embodiments of the Invention

[0113] Based on the data from Examples 1 to 14, combined with Figure 3 and Figure 4 As shown, it can be seen that: When the epoxy resin content is 20%: As the pressure increases from 14.8 MPa to 25.9 MPa, both flexural strength and tensile strength significantly increase, reaching 34.7 MPa and 21.2 MPa, respectively, at 25.9 MPa. When the pressure continues to increase to 37.0 MPa, 48.0 MPa, and 59.1 MPa, the strength remains at a high level, with the tensile strength reaching its maximum value of 23.8 MPa at 59.1 MPa. When the pressure exceeds 70.2 MPa, both flexural strength and tensile strength begin to decrease, dropping to 25.8 MPa and 17.8 MPa, respectively, at 81.3 MPa.

[0114] When the epoxy resin content is 30%: During the pressure increase from 14.8 MPa to 37.0 MPa, the flexural strength and tensile strength continuously increase, reaching peak values ​​of 44.6 MPa and 25.0 MPa, respectively, at 37.0 MPa. Within the pressure range of 37.0 MPa to 59.1 MPa, the strength remains at a high level, with the flexural strength remaining above 43.6 MPa. After the pressure exceeds 70.2 MPa, the strength begins to decrease, dropping to 36.0 MPa and 22.8 MPa at 81.3 MPa.

[0115] The effect of pressure on flexural strength and tensile strength shows a trend of first increasing and then decreasing, with an optimal pressure range. When the epoxy resin ratio is 20%, the optimal pressure range is 25.9 MPa to 59.1 MPa; when the epoxy resin ratio is 30%, the optimal pressure range is 25.9 MPa to 59.1 MPa, with 37.0 MPa being the optimal pressure point.

[0116] Comparing under the same pressure conditions: at 14.8 MPa, the flexural strength of the epoxy resin with a 30% epoxy resin content (41.0 MPa) is significantly higher than that of the 20% content (26.4 MPa). At 25.9 MPa, the flexural strength of the epoxy resin with a 30% content (40.9 MPa) is higher than that of the 20% content (34.7 MPa). At 37.0 MPa, the flexural strength of the epoxy resin with a 30% content (44.6 MPa) is higher than that of the 20% content (32.5 MPa). At 48.0 MPa, the flexural strength of the epoxy resin with a 30% content (44.2 MPa) is higher than that of the 20% content (31.3 MPa). At 59.1 MPa, the flexural strength of the epoxy resin with a 30% content (43.6 MPa) is higher than that of the 20% content (32.5 MPa). At a pressure of 70.2 MPa, the flexural strength of the 30% fraction (38.8 MPa) is higher than that of the 20% fraction (28.8 MPa). At a pressure of 81.3 MPa, the flexural strength of the 30% fraction (36.0 MPa) is higher than that of the 20% fraction (25.8 MPa).

[0117] Under all pressure conditions, the flexural strength and tensile strength of the 30% epoxy resin ratio were better than those of the 20% ratio, indicating that increasing the epoxy resin ratio helps to enhance the mechanical properties of the board.

[0118] In summary, the preparation method of this invention only requires crushing corn stalks to a fiber length of 2-3 mm, eliminating the need for complex pretreatment steps such as peel and pulp separation, enzyme etching, nanocellulose impregnation, or preservative treatment. The corn stalk powder is directly mixed with epoxy resin powder of 500 mesh size in a specific ratio, and then hot-pressed at 150°C and 10-90 MPa. All embodiments employ a uniform three-step process of crushing, mixing, and hot-pressing, resulting in a concise process flow, low equipment requirements, and significant savings in time and economic costs, making it suitable for large-scale production.

[0119] This invention utilizes the synergistic reinforcing effect of the hydrogen bond network formed by cellulose, hemicellulose, and lignin in corn stalks under high temperature and pressure, combined with the bonding effect of epoxy resin, to produce composite boards with excellent mechanical properties. As shown in Example 10, when the epoxy resin ratio is 30%, the pressure is 37.0 MPa, and the temperature is 150°C, the flexural strength of the composite board reaches 44.6 MPa, and the tensile strength reaches 25.0 MPa. The data from these examples show that when the epoxy resin ratio is 30% and the pressure is controlled within the range of 25.9 MPa to 59.1 MPa, the flexural strength remains above 40.9 MPa, and the tensile strength remains above 21.8 MPa, demonstrating stable mechanical properties that are significantly superior to glue-free boards that rely solely on the hydrogen bonds within the corn stalks themselves.

[0120] This invention uses epoxy resin powder as the sole adhesive. The entire preparation process does not involve the addition of formaldehyde-containing adhesives such as resorcinol-modified phenolic resin, nor does it include preservative impregnation. As shown in Examples 1 to 14, none of the examples used any formaldehyde-containing chemical reagents during the preparation process. The resulting composite boards release no formaldehyde or other volatile organic compounds during production and use, posing no harm to human health or environmental safety, and conforming to the concept of green environmental protection.

[0121] The preparation method described in this invention can obtain composite boards with satisfactory mechanical properties within a wide pressure range. As shown in Examples 1 to 14, when the epoxy resin ratio is 30%, the flexural strength reaches above 36.0 MPa and the tensile strength reaches above 18.0 MPa within a pressure range of 14.8 MPa to 81.3 MPa; when the epoxy resin ratio is 20%, the flexural strength reaches above 31.3 MPa and the tensile strength reaches above 21.0 MPa within a pressure range of 25.9 MPa to 59.1 MPa. This indicates that the present invention has good adaptability to different pressure conditions, facilitating flexible adjustment of process parameters according to equipment conditions in actual production.

[0122] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0123] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an epoxy resin-based corn stalk composite board, characterized in that, Includes the following steps: S1. Crush the corn stalks and sieve them to obtain corn stalk powder with a fiber length of 2-3 mm; S2. The corn stalk powder and epoxy resin powder are mixed at a mass ratio of 8:2 or 7:3 to obtain a mixed raw material; S3. The mixed raw materials are placed under a temperature of 140-160℃ and a pressure of 10-90MPa for heat preservation and pressure treatment for at least 2 hours. After that, the material is demolded to obtain the epoxy resin-based corn stalk composite board.

2. The preparation method according to claim 1, characterized in that, In S1, the corn stalks are cut into small pieces and then crushed as a whole without separating the skin and pulp.

3. The preparation method according to claim 1, characterized in that, In step S2, the corn stalk powder and the epoxy resin powder are mixed evenly by mechanical stirring or manual shaking.

4. An epoxy resin-based corn stalk composite board, characterized in that, The epoxy resin-based corn stalk composite board was prepared using the preparation method described in any one of claims 1 to 3.

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