A kind of attapulgite reinforced bamboo-based fiber composite material and preparation method thereof

Abstract

The present invention belongs to the field of high-strength composite materials, and relates to a attapulgite-reinforced bamboo-based fiber composite material and a preparation method thereof. The raw materials thereof include: bamboo fiber, water, phenolic resin and a reinforcing agent; the reinforcing agent is selected from chitosan / ball-milled KH550 modified attapulgite powder. The process flow of the present invention is simple, and the inorganic material attapulgite powder is used as a reinforcing agent, which improves the mechanical properties of the material while reducing environmental pollution. The "attapulgite-reinforced bamboo-based fiber composite material" provided by the present invention is expected to be widely used in the fields of energy-saving buildings, transportation, etc. to replace some metal materials such as steel.

Description

Technical Field

[0001] The invention belongs to the field of high-strength composite materials and relates to an attapulgite-reinforced bamboo-based fiber composite material and a preparation method thereof. Background Art

[0002] With the emphasis on sustainable development of the construction industry and environmental protection, vigorously developing new green and environmentally friendly building materials is the inevitable direction of civil engineering development. As an excellent reinforcing material, various natural plant fibers (such as wheat straw, bagasse, hemp fiber, bamboo fiber, etc.) have the advantages of being cheap, recyclable, degradable, and renewable compared to glass fiber and carbon fiber. Among them, bamboo, as a natural fiber-reinforced composite material, has a wide range of uses. As a building material, bamboo has a large carbon storage during its growth process, and the energy consumption during processing is less than other commonly used building materials. Compared with wood, its growth cycle is much shorter, and it can be degraded after being discarded.

[0003] However, the mechanical properties of natural bamboo are relatively poor, and it is difficult to meet the needs of the engineering field for high-performance structural materials. For example, the strength of natural bamboo is lower than that of steel, alloy and other materials, and it cannot be used in large load-bearing structures. In addition, bamboo has a series of disadvantages such as easy water absorption, shrinkage and swelling, low dimensional stability, poor wear resistance and low hardness, which also limit its application in the engineering field. Due to the density of bamboo fiber (1.45 g / cm 3 )than traditional metal (2.7~8 g / cm 3 ) has a much lower density, and its specific strength is greater than that of high-strength steel and some lightweight titanium alloys. At present, the mechanical properties of various bamboo-based materials, such as strength, modulus and toughness, are far lower than those of bamboo fibers, indicating that there is still a lot of room for development. Effectively exerting the mechanical properties of bamboo fibers to prepare high-performance bamboo-based composite materials has broad application prospects.

[0004] Li Yuanqing et al. (CN112356196A) obtained a "bamboo steel" composite material with high fiber content by 1) removing lignin and hemicellulose from bamboo in two steps, 2) opening up the pore structure inside the bamboo using freeze-drying technology, 3) vacuum impregnating the obtained bamboo skeleton with epoxy resin, and 4) hot pressing and curing to achieve densification of the bamboo. The "bamboo steel" material provided by this invention has the advantages of high bamboo utilization rate, excellent mechanical properties, high dimensional stability, low thermal conductivity, etc., and is expected to be used in energy-saving buildings, bridges, transportation, aerospace and other fields.

[0005] Yin Yingwu et al. (CN113386235A) provided a cellulose natural skeleton-based "bamboo steel" and its processing technology, wherein the bamboo steel profile contains cellulose and a viscous polymer. A bamboo sheet material with an internal cavity and original shape is obtained by hot alkaline solution, and then a synthetic viscous polymer is added and dried to obtain a three-repair bamboo sheet material with a natural skeleton structure, and then hot pressing is used to obtain a light green bamboo steel or bamboo profile with a density greater than 1, a strength exceeding that of steel, and strong corrosion resistance and flame retardancy.

[0006] Gao Jie et al. (CN114393664A) plasticized bamboo fiber bundles in a plasticizer solution to obtain plasticized bamboo fiber bundles; oxidized and impregnated the plasticized bamboo fiber bundles to obtain carbonized bamboo fiber bundles; and then impregnated and hot-pressed the carbonized bamboo fiber bundles to obtain bamboo-based fiber composite materials. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a attapulgite reinforced bamboo-based fiber composite material and a preparation method thereof.

[0008] The present invention is achieved through the following technical solutions:

[0009] A attapulgite-reinforced bamboo-based fiber composite material, the raw materials of which include bamboo fiber, water, phenolic resin and a reinforcing improver; the reinforcing improver is selected from chitosan / ball-milled KH550 modified attapulgite powder.

[0010] Furthermore, the preparation method of the chitosan / ball-milled KH550 modified attapulgite powder is:

[0011] The preparation method of the chitosan / ball-milled KH550 modified attapulgite powder is:

[0012] 2.5 g of chitosan was dispersed in 150 mL of 2 wt% acetic acid solution, and then heated to 60°C with stirring, and maintained at 60°C for 4 hours to obtain a chitosan solution;

[0013] 25 g of ball-milled KH550 modified attapulgite powder was slowly added to the chitosan solution. After stirring at 30° C. for 4 hours, the pH was adjusted to neutral with 0.1 M NaOH solution, and a precipitate was obtained by centrifugation. The precipitate was washed 3 times with deionized water, and then dried at 65° C. for 24 hours to obtain chitosan / ball-milled KH550 modified attapulgite powder.

[0014] The preparation method of the ball-milled KH550 modified attapulgite powder is:

[0015] S1, adding 10 g of attapulgite powder to 100 mL of 1 M dilute sulfuric acid, stirring for 0.5 h, then repeatedly washing the precipitate with deionized water until the pH of the filtrate is neutral, and drying at 100 ° C for 8 h to obtain acid-treated attapulgite powder;

[0016] S2, 3 g of acid-treated attapulgite powder, 0.09 g of KH550, 16 mL of deionized water, and 10 mL of anhydrous ethanol were added to a planetary ball mill. The intermittent ball milling process was adopted. The ball mill was operated for 6 minutes, paused for 3 minutes, and the ball mill was operated at a speed of 400 r / min for a total of 10 hours;

[0017] S3, washing the product obtained in step S2 with deionized water for three times, and then vacuum drying to obtain KH550 modified attapulgite powder.

[0018] Furthermore, the mass ratio of water to phenolic resin is 1:1. The mass of the chitosan / ball-milled KH550 modified attapulgite powder is 1% to 8% of the total mass of water and phenolic resin.

[0019] The present invention also provides a method for preparing attapulgite-reinforced bamboo-based fiber, the preparation method comprising the following steps:

[0020] Step S1, cutting the processed bamboo fiber to obtain bamboo fiber sheets with a length of 160 mm and a thickness of 3-10 mm;

[0021] Step S2, mixing water and phenolic resin to dilute, then adding a reinforcing agent to the diluted mixed solution, and stirring evenly;

[0022] Step S3, putting the bamboo fiber into the mixed solution, soaking for 15 minutes, taking it out, and placing it in a cool and ventilated place to dry naturally after the liquid on its surface has dripped dry;

[0023] Step S4, stacking the dried bamboo fiber sheets neatly in a mold, stacking 4 layers, and then performing hot pressing treatment according to the set hot pressing conditions; the hot pressing conditions are 100°C, 26Mpa, 10min. Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] The process flow of the present invention is simple, and the inorganic material of attapulgite powder is used as a reinforcing agent, which reduces environmental pollution while improving the mechanical properties of the material. Attapulgite, also known as palygorskite, is a layered chain structure of hydrated magnesium-rich aluminum silicate adhesive minerals, with a special fiber structure and a large specific surface area. Its fiber structure can play a role in fiber toughening, thereby improving the mechanical properties of the composite board. The specific strength of the "attapulgite-reinforced bamboo-based fiber composite material" provided by the present invention is higher than that of steel, but its density and thermal conductivity are much lower than those of metal materials such as steel. The "attapulgite-reinforced bamboo-based fiber composite material" provided by the present invention is expected to replace part of the metal materials such as steel in the fields of energy-saving buildings, transportation and the like and be widely used. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0026] Figure 1 This is a scanning electron microscope image of the attapulgite powder used in the present invention.

[0027] Figure 2 The actual picture of the "bamboo-based composite material" prepared by the present invention, (a) cross section; (b) front view. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0029] Example 1

[0030] Step S1, cutting the processed bamboo fiber to obtain bamboo fiber sheets with a length of 160 mm and a thickness of 3-10 mm;

[0031] Step S2, mixing water and phenolic resin in proportion to dilute, and then adding attapulgite powder to the diluted mixed solution in a mass ratio (attapulgite powder / phenolic resin) of 1%, 2%, 6%, and 8%, and stirring evenly;

[0032] Step S3, putting 8 pieces of bamboo fibers into the mixed solution, soaking them for 15 minutes, taking them out, and placing them in a cool and ventilated place to dry naturally after the liquid on their surface has dripped dry;

[0033] Step S4, the dried bamboo pieces are neatly stacked in a 160mm*80mm mold, stacked in 4 layers, and then hot-pressed according to the set hot-pressing conditions. The obtained profile is naturally cooled, and then cut into bamboo strips with a specification of 160mm*10mm*t (t is the thickness of the profile), and the mechanical properties are tested after being placed at room temperature for 24 hours. The results are shown in Table 1.

[0034] Table 1 Preparation conditions and product properties of attapulgite reinforced hot-pressed bamboo-based fiber composites

[0035]

[0036] Table 1: In the profiles reinforced with attapulgite powder, the bending strength of bamboo is significantly improved after hot pressing. Among them, the comparison between No. 1 and No. 2 shows that the reinforcing effect of the diluted phenolic resin on bamboo fiber is more significant. After adding attapulgite powder, the strength of the composite material is further improved, and the maximum value of 292Mpa is obtained when the addition amount is 1%, and its elastic modulus is 26730MPa. However, with the further increase of the content of attapulgite powder, the strength of the composite material obtained does not increase linearly, but decreases, indicating that the reinforcing effect of attapulgite powder on bamboo fiber has a favorable range. According to the literature on recombinant bamboo, when the elastic modulus is 18000MPa, the static bending strength reaches 160MPa, which is a superior product. The static bending strength of profile No. 3 is 292MPa, which is 1.62 times better than the superior product; the elastic modulus is 26730Mpa, which is 1.49 times that of the superior product.

[0037] Example 2

[0038] Step S1, cutting the processed bamboo fiber to obtain bamboo fiber sheets with a length of 160 mm and a thickness of 3-10 mm;

[0039] Step S2, 500 g of water and 500 g of phenolic resin are mixed and diluted, and chitosan / ball-milled KH550 modified attapulgite powder is added to the diluted mixed solution at a mass ratio (attapulgite powder / phenolic resin) of 1%, 2%, 3%, 6%, and 8%, and stirred evenly;

[0040] Step S3, putting 8 pieces of bamboo fibers into the mixed solution, soaking them for 15 minutes, taking them out, and placing them in a cool and ventilated place to dry naturally after the liquid on their surface has dripped dry;

[0041] Step S4, the dried bamboo pieces are neatly stacked in a 160mm*80mm mold, stacked in 4 layers, and then hot-pressed according to the set hot-pressing conditions (100℃, 26Mpa, 10min). The obtained profile is naturally cooled, and then cut into bamboo strips with a specification of 160mm*10mm*t (t is the thickness of the profile), and then placed at room temperature for 24h before mechanical properties testing. The results are shown in Table 2.

[0042] The preparation method of the chitosan / ball-milled KH550 modified attapulgite powder is:

[0043] 2.5 g of chitosan was dispersed in 150 mL of 2 wt% acetic acid solution, and then heated to 60°C with stirring, and maintained at 60°C for 4 hours to obtain a chitosan solution;

[0044] 25 g of ball-milled KH550 modified attapulgite powder was slowly added to the chitosan solution. After stirring at 30° C. for 4 hours, the pH was adjusted to neutral with 0.1 M NaOH solution, and a precipitate was obtained by centrifugation. The precipitate was washed 3 times with deionized water, and then dried at 65° C. for 24 hours to obtain chitosan / ball-milled KH550 modified attapulgite powder.

[0045] The preparation method of the ball-milled KH550 modified attapulgite powder is:

[0046] S1, adding 10 g of attapulgite powder to 100 mL of 1 M dilute sulfuric acid, stirring for 0.5 h, then repeatedly washing the precipitate with deionized water until the pH of the filtrate is neutral, and drying at 100 ° C for 8 h to obtain acid-treated attapulgite powder;

[0047] S2, 3 g of acid-treated attapulgite powder, 0.09 g of KH550, 16 mL of deionized water, and 10 mL of anhydrous ethanol were added to a planetary ball mill. The intermittent ball milling process was adopted. The ball mill was operated for 6 minutes, paused for 3 minutes, and the ball mill was operated at a speed of 400 r / min for a total of 10 hours;

[0048] S3, washing the product obtained in step S2 with deionized water for three times, and then vacuum drying to obtain KH550 modified attapulgite powder.

[0049] Table 2 Preparation conditions and product properties of modified attapulgite reinforced hot-pressed bamboo-based fiber composites

[0050]

Claims

1. A attapulgite-reinforced bamboo-based fiber composite material, characterized in that: Its raw materials include: Bamboo fiber, water, phenolic resin and reinforcing agent; The reinforcing improver is selected from chitosan / ball-milled KH550 modified attapulgite powder; The preparation method of the chitosan / ball-milled KH550 modified attapulgite powder is: 2.5 g of chitosan was dispersed in 150 mL of 2 wt% acetic acid solution, and then heated to 60 °C with stirring, and maintained at 60 °C for 4 hours to obtain a chitosan solution; 25 g of ball-milled KH550 modified attapulgite powder was slowly added to the chitosan solution, and after stirring at 30°C for 4 hours, the pH was adjusted to neutral with 0.1 M NaOH solution, and a precipitate was obtained by centrifugation. The precipitate was washed with deionized water for 3 times, and then the precipitate was dried at 65°C for 24 hours to obtain chitosan / ball-milled KH550 modified attapulgite powder; The preparation method of the ball-milled KH550 modified attapulgite powder comprises the following steps: S1, adding 10 g of attapulgite powder to 100 mL of 1 M dilute sulfuric acid, stirring for 0.5 h, then repeatedly washing the precipitate with deionized water until the pH of the filtrate is neutral, and drying at 100 ° C for 8 h to obtain acid-treated attapulgite powder; S2, 3 g of acid-treated attapulgite powder, 0.09 g of KH550, 16 mL of deionized water, and 10 mL of anhydrous ethanol were added to a planetary ball mill. The intermittent ball milling process was adopted. The ball mill was operated for 6 minutes, paused for 3 minutes, and the ball mill was operated at a speed of 400 r / min for a total of 10 hours; S3, washing the product obtained in step S2 with deionized water for three times, and then vacuum drying to obtain ball-milled KH550 modified attapulgite powder; The mass of the chitosan / ball-milled KH550 modified attapulgite powder is 1% of the mass of the phenolic resin; The mass ratio of water to phenolic resin is 1:1; The preparation method of the attapulgite-reinforced bamboo-based fiber composite material comprises the following steps: Step S1, cutting the processed bamboo fiber to obtain bamboo fiber sheets with a length of 160 mm and a thickness of 3-10 mm; Step S2, mixing water and phenolic resin to dilute, then adding a reinforcing agent to the diluted mixed solution, and stirring evenly; Step S3, placing the bamboo fiber sheet in the mixed solution, soaking for 15 minutes, taking it out, and placing it in a cool and ventilated place to dry naturally after the liquid on its surface has dripped dry; Step S4, stacking the dried bamboo fiber sheets neatly in a mold, stacking 4 layers, and then performing hot pressing treatment according to set hot pressing conditions; the hot pressing conditions are 100° C., 26 MPa, and 10 min.

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