High-strength bamboo chip and preparation method thereof

Abstract

The application belongs to the field of high polymer material preparation, and particularly relates to a preparation method of high-strength bamboo chips. The application provides a preparation method of high-strength bamboo chips, which comprises the following steps: reacting flaky bamboo materials from which bamboo yellow and bamboo green have been removed with lye, and washing with hot water after the reaction is completed; and drying the bamboo materials by using a vacuum hot-pressing method. The application uses moso bamboo with an age of one month, and the strength of the bamboo chips can be as high as 588 MPa.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation, specifically relating to a method for preparing high-strength bamboo strips. Background Technology

[0002] Bamboo possesses significant structural and environmental advantages, including rapid growth, moisture resistance, weather resistance, and structural rigidity. Bamboo grows quickly with a short growth cycle. Traditionally, bamboo is an inexpensive and abundant material; the tensile strength of mature bamboo is comparable to low-carbon steel, and it has been widely used in furniture, construction, bridges, and other fields. Bamboo's properties are comparable to mild steel. In recent years, efforts have been made to process bamboo into sustainable, environmentally friendly, economical, and high-performance composite materials. Pretreatments such as bleaching, saturated steam, hot oil, or resin filling followed by densification all enhance the mechanical properties of natural bamboo. However, the increase in mechanical strength is not significant, generally reaching a tensile strength of 200-300 MPa.

[0003] Chen Chaoji et al. reported the preparation of high-strength, lightweight bamboo structural materials through partial delignification and microwave heating, while Wang Youyong et al. proposed a method to transform natural bamboo into bamboo steel. The preparation process of bamboo steel involves the removal of lignin and hemicellulose, freeze-drying followed by epoxy infiltration, and densification bonding with in-situ solidification. The resulting bamboo steel is a super-strong composite material with high specific tensile strength. Most literature reporting the transformation of natural bamboo into high-strength, lightweight structural materials uses bamboo or wood with a longer bamboo or wood age, resulting in high lignin content. Therefore, the prerequisite for preparation is partial delignification using sodium chlorite, or the formation of a composite material after delignification to increase its height. Currently, there are no reports on the technology of preparing high-strength bamboo chips using young bamboo. Summary of the Invention

[0004] To address the above problems, this invention provides a method for preparing high-strength bamboo strips, comprising the following steps:

[0005] (1) React sheet bamboo with alkaline solution, and wash it with hot water after the reaction is complete;

[0006] (2) Dry it by vacuum hot pressing to obtain the finished product.

[0007] Furthermore, the sheet bamboo material mentioned in step (1) is sheet bamboo material with the yellow and green bamboo removed.

[0008] Furthermore, the sheet bamboo material mentioned in step (1) is moso bamboo with an age of 15-30 days and the thickness of the bamboo sheet is 1.5mm-2mm.

[0009] Furthermore, the mass concentration of the alkaline solution in step (1) is 5%–7%.

[0010] Furthermore, the alkaline solution mentioned in step (1) is a sodium hydroxide solution.

[0011] Furthermore, in step (1), the raw materials react with the alkaline solution, the mass ratio of bamboo to alkaline solution is 1:100, and the reaction time is 8 hours.

[0012] Furthermore, in step (2), the vacuum degree of the vacuum hot pressing is -0.1MPa, the temperature is 70℃, and the drying time is 10min.

[0013] The present invention also provides a high-strength bamboo strip, which is prepared by any of the above preparation methods.

[0014] The present invention has the following beneficial effects:

[0015] This invention requires only two steps: low-concentration alkali treatment followed by vacuum hot pressing, to produce high-strength bamboo strips. Using the technical solution provided by this invention, and employing moso bamboo less than one month old, combined with the preparation method described in this application, the strength of the bamboo strips can reach as high as 588 MPa. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 Mechanical properties of the sample;

[0018] Figure 2 Cellulose structural crystal form. Detailed Implementation

[0019] Various exemplary embodiments of the present invention are now described in detail. Unless otherwise specified, the methods used in the embodiments are conventional methods, and the reagents used are commercially available reagents or reagents prepared using conventional methods. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0020] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] Implementation Case 1

[0025] (1) Remove the yellow and green bamboo from the young bamboo at an age of (15-30) days and cut it into bamboo slices with a thickness of 1.5mm-2mm. Without any other chemical treatment, dry the sample by vacuum hot pressing at a vacuum degree of -0.1MPa and a temperature of 70℃ for 10 minutes to obtain sample NB.

[0026] The mechanical properties of the obtained samples are as follows Figure 1 The tensile strength shown in Table 1 is 284.38 MPa. The contents of lignin, hemicellulose, and cellulose are shown in Table 2. The cellulose crystal structure is as follows: Figure 2 As shown, this is cellulose type I.

[0027]

[0028] Table 1 Mechanical properties of the samples

[0029] Table 2. Content of lignin, hemicellulose, and cellulose

[0030]

[0031] Implementation Case 2

[0032] (1) Remove the yellow and green parts of young bamboo at an age of (15-30) days, and cut them into bamboo strips with a thickness of 1.5 mm-2 mm. Mix them with a 5% sodium hydroxide aqueous solution at a solid-liquid mass ratio of 1:100, and react at 80℃ for 8 hours.

[0033] (2) The sample obtained in step (1) was washed with hot water until neutral and dried for 10 minutes using a vacuum hot pressing method with a vacuum degree of -0.1 MPa and a temperature of 70°C to obtain sample DB-5.

[0034] The mechanical properties of the obtained samples are as follows Figure 1 The tensile strength shown in Table 1 is

[0035] The pressure was 449.17 MPa. The contents of lignin, hemicellulose, and cellulose are shown in Table 2. The cellulose crystal structure is as follows: Figure 2 As shown, this is cellulose type I.

[0036] Implementation Case 3

[0037] (1) Remove the yellow and green parts of young bamboo at an age of (15-30) days, and cut them into bamboo strips with a thickness of 1.5 mm-2 mm. Mix them with a 7% sodium hydroxide aqueous solution at a solid-liquid mass ratio of 1:100, and react at 80℃ for 8 hours.

[0038] (2) The sample obtained in step (1) was washed with hot water until neutral and dried for 10 minutes using a vacuum hot pressing method with a vacuum degree of -0.1 MPa and a temperature of 70°C to obtain sample DB-7.

[0039] The mechanical properties of the obtained samples are as follows Figure 1 The tensile strength shown in Table 1 is 588.63 MPa. The contents of lignin, hemicellulose, and cellulose are shown in Table 2. The cellulose crystal structure is as follows: Figure 2 As shown, this is cellulose type I.

[0040] Implementation Case 4

[0041] (1) Remove the yellow and green parts of young bamboo at an age of (15-30) days, and cut them into bamboo strips with a thickness of 1.5 mm-2 mm. Mix them with a 10% sodium hydroxide aqueous solution at a solid-liquid mass ratio of 1:100, and react at 80℃ for 8 hours.

[0042] (2) The sample obtained in step (1) was washed with hot water until neutral and dried for 10 minutes by vacuum hot pressing at a vacuum degree of -0.1 MPa and a temperature of 70°C to obtain sample DB-10.

[0043] The mechanical properties of the obtained samples are as follows Figure 1 The tensile strength shown in Table 1 is 330.10 MPa. The contents of lignin, hemicellulose, and cellulose are shown in Table 2. The cellulose crystal structure is as follows: Figure 2 As shown, this is cellulose type II.

[0044] Implementation Case 5

[0045] (1) Remove the yellow and green parts of young bamboo at an age of (15-30) days, and cut them into bamboo strips with a thickness of 1.5 mm-2 mm. Mix them with a 20% sodium hydroxide aqueous solution at a solid-liquid mass ratio of 1:100, and react at 80℃ for 8 hours.

[0046] (2) The sample obtained in step (1) was washed with hot water until neutral and dried for 10 minutes by vacuum hot pressing at a vacuum degree of -0.1 MPa and a temperature of 70°C to obtain sample DB-20.

[0047] The mechanical properties of the obtained samples are as follows Figure 1 The tensile strength shown in Table 1 is 230.41 MPa. The contents of lignin, hemicellulose, and cellulose are shown in Table 2. The cellulose crystal structure is as follows: Figure 2 As shown, this is cellulose type II.

[0048] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing high-strength bamboo strips, characterized in that, Includes the following steps: (1) The sheet bamboo is reacted with alkaline solution. After the reaction is complete, it is washed with hot water. The sheet bamboo is moso bamboo with an age of 15-30 days. The mass concentration of the alkaline solution is 5%-7%. (2) Dry it using vacuum hot pressing to obtain the finished product; The sheet bamboo material mentioned in step (1) is sheet bamboo material with the yellow and green bamboo removed; The thickness of the bamboo strips mentioned in step (1) is 1.5mm-2mm; The alkaline solution mentioned in step (1) is a sodium hydroxide solution; The raw materials described in step (1) react with the alkaline solution, with the mass ratio of bamboo to alkaline solution being 1:100 and the reaction time being 8 hours. The vacuum degree of the vacuum hot pressing in step (2) is -0.1MPa, the temperature is 70℃, and the drying time is 10min.

2. A high-strength bamboo strip, characterized in that, It is prepared by the preparation method described in claim 1.

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