Bamboo fiber reinforced bio-based nylon composite material and preparation method thereof

Abstract

The application provides a bamboo fiber reinforced bio-based nylon composite material and a preparation method thereof, wherein bio-based nylon B1000, oxidized bamboo powder, amino-terminated polyamide and an auxiliary agent are mixed according to a mass ratio of 61:20:6:13, and the bamboo fiber reinforced bio-based nylon composite material is formed through dense mixing compounding. The amino-terminated polyamide is introduced into the bamboo plastic composite material, so that the composite material presents a significant interface reinforcement effect. Meanwhile, the aldehyde groups in the oxidized bamboo powder and the amino groups of the amino-terminated polyamide form a covalent bond, and the uniform dispersion of the filler is realized through the cooperation of the dense mixing and the strong shearing effect, so that the composite material presents excellent toughness and mechanical properties. The composite material preparation process is simple, green and environmentally friendly, and has a wide application prospect in the fields of structural parts, lightweight materials, wear-resistant parts and the like.

Description

Technical Field

[0001] This invention relates to the field of bamboo-plastic composite materials technology, specifically to a bamboo fiber reinforced bio-based nylon composite material and its preparation method. Background Technology

[0002] Bamboo-plastic composites combine the advantages of both bamboo and plastic, making them a widely used and environmentally friendly material. Bamboo powder, as a natural plant fiber, is rich in hydroxyl groups on its surface, exhibiting strong hydrophilicity; while polyamides and thermoplastics are hydrophobic. The significant difference in polarity between the two results in weak interfacial bonding when directly composited, easily forming a "defect interface." Under external forces, stress concentration can easily occur, leading to brittle fracture and poor impact toughness, severely impacting the service life and safety of bamboo-plastic composites.

[0003] Current conventional compatibilizer, fiber reinforcement, or irreversible crosslinking modification methods suffer from poor interfacial compatibility, resulting in a failure to improve toughness. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to address poor interfacial compatibility and thereby improve the toughness of bamboo-plastic composite materials.

[0005] The present invention solves the above-mentioned technical problems through the following technical means: The first aspect of this invention provides a method for preparing a bamboo fiber reinforced bio-based nylon composite material. Bio-based nylon B1000, oxidized bamboo powder, amino-terminated polyamide, and additives are mixed in a mass ratio of 61:20:6:13, and then compounded by intensive mixing to form the bamboo fiber reinforced bio-based nylon composite material. The oxidized bamboo powder contains aldehyde groups, and the amino-terminated polyamide has the following structural formula: , 5≤y≤15.

[0006] Beneficial Effects: This invention introduces amino-terminated polyamide into bamboo-plastic composites, resulting in a significant interfacial reinforcement effect. Simultaneously, the aldehyde groups in oxidized bamboo powder form covalent bonds with the amino groups of the amino-terminated polyamide, and the combined effect of intensive mixing and strong shearing achieves uniform dispersion of the filler, leading to excellent toughness and mechanical properties in the composite material. The composite material preparation process of this invention is simple and environmentally friendly, and it has broad application prospects in structural components, lightweight materials, and wear-resistant parts.

[0007] Preferably, the mixing temperature is 190~200℃ and the time is 8~10min.

[0008] Preferably, the amino-terminated polyamide is prepared by the following method: a diacid and hexamethylenediamine are melt-polymerized under a catalyst and nitrogen atmosphere via a stepped heating process; wherein the structural formula of the diacid is: .

[0009] Preferably, the molar ratio of dicarboxylic acid, hexamethylenediamine and catalyst is 50:100:1.5; the catalyst is hypophosphite.

[0010] Preferably, the stepped heating is as follows: react at 100℃ for 1 hour, then increase the temperature to 140℃ for 1.5 hours, then increase the temperature to 160℃ for 1.5 hours, then increase the temperature to 190℃ for 3 hours, and finally evacuate to... Continue the reaction at 0.09 MPa for 2.5 hours.

[0011] Preferably, oxidized bamboo powder is prepared by dispersing bamboo powder in water and adding sodium periodate under light-protected conditions to carry out an oxidation reaction.

[0012] Preferably, the mass ratio of bamboo powder to sodium periodate is 1:1.

[0013] Preferably, the oxidation temperature is 45~50℃ and the time is 10~12h.

[0014] Preferably, the adjuvant is obtained by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0015] The second aspect of the present invention provides a method for preparing the above-mentioned bamboo fiber reinforced bio-based nylon composite material to obtain the bamboo fiber reinforced bio-based nylon composite material.

[0016] Beneficial effects: Under high-temperature shearing, the aldehyde groups on the surface of oxidized bamboo powder undergo a condensation reaction with the amino groups of the amino-terminated polyamide, generating dynamic imine bonds (Schiff base network) in situ. The flexible segments of the amino-terminated polyamide intercalate within the bio-based nylon B1000 matrix, providing toughening, ultimately resulting in a high-strength and high-toughness composite material. The composite material exhibits a tensile strength of 32.4 MPa, an elongation at break of 39.9%, and a toughness of 10.23 kJ / m. 3 . Attached Figure Description

[0017] Figure 1 This is the infrared spectrum of oxidized bamboo powder in Example 1 of the present invention; Figure 2 This is a synthesis pathway diagram of the amino-terminated polyamide in Example 1 of the present invention; Figure 3 This is the 1H NMR spectrum of the amino-terminated polyamide in Example 1 of this invention; Figure 4 This is the infrared spectrum of the diacid, amino-terminated polyamide and bamboo fiber reinforced bio-based nylon composite material in Example 1 of the present invention; Figure 5 These are stress-strain curves of the composite materials obtained in the embodiments and comparative examples of the present invention; Figure 6 This is a comparison diagram of the toughness of the composite materials prepared in the embodiments and comparative examples of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0020] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0021] The bio-based nylon B1000 used in the examples and comparative examples was purchased from Anhui Baimai New Material Technology Co., Ltd.

[0022] The adjuvants used in the examples and comparative examples were obtained by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0023] Example 1 This embodiment provides a method for preparing bamboo fiber reinforced bio-based nylon composite material, specifically including the following steps: S1 Preparation of oxidized bamboo powder 100 parts by weight of 200-mesh bamboo powder (BF) were placed in a round-bottom flask and dispersed in deionized water under magnetic stirring for 2 minutes. Then, 100 parts by weight of sodium periodate were added, and the round-bottom flask was wrapped with aluminum foil to prevent the sodium periodate from decomposing in light. The reaction was then carried out at 50°C for 12 hours. After the reaction was completed, the modified bamboo powder was collected by vacuum filtration, washed three times with deionized water and ethylene glycol, and then dried in a vacuum oven at 80°C for 12 hours to obtain oxidized bamboo powder (OBF) with aldehyde groups on the surface.

[0024] according to Figure 1 It can be seen that OBF is at 1724cm -1 The presence of an aldehyde peak indicates that the bamboo powder was successfully oxidized by sodium periodate.

[0025] S2 Preparation of amino-terminated polyamides according to Figure 2As shown, a dicarboxylic acid, hexamethylenediamine, and hypophosphite were added to a three-necked flask in a molar ratio of 50:100:1.5. Nitrogen gas was bubbled through the flask for 20 minutes, and the mixture was mechanically stirred and reacted in an oil bath at 100°C for 1 hour. The temperature was then increased to 140°C and reacted for 1.5 hours, followed by 160°C and reacting for 1.5 hours. Finally, the temperature was increased to 190°C and reacted for 3 hours. The mixture was then evacuated to a vacuum. The reaction was continued at 0.09 MPa for 2.5 h, then cooled and discharged to obtain amino-terminated polyamide (PrePA). The amino-terminated polyamide had a molecular weight of 4500, where y was approximately 7.

[0026] according to Figure 3 It can be seen that the amino-terminated polyamide contains methylene groups, as well as -CONH-CH2- at c1 and c2 and H2N-CH2- at b1 and b2, indicating that the amino-terminated polyamide was successfully synthesized.

[0027] S3 Preparation of Bamboo Fiber Reinforced Bio-based Nylon Composites Bio-based nylon B1000, oxidized bamboo powder, and amino-terminated polyamide were dried in an oven at 80 ℃ for 12 h. 61 parts by weight of bio-based nylon B1000, 20 parts by weight of oxidized bamboo powder, 6 parts by weight of amino-terminated polyamide, and 13 parts by weight of additives were mixed and added to a mixer. The mixture was then mixed at 190 ℃ and 100 rpm for 8 min, and extruded to obtain a bamboo fiber reinforced bio-based nylon composite material.

[0028] according to Figure 4 It can be known that 1633cm -1 The presence of imine bonds indicates that an amino-terminated polyamide and oxidized bamboo powder underwent a chemical reaction.

[0029] Comparative Example 1 This comparative example provides a nylon composite material, which is prepared according to the following method: Bio-based nylon B1000 and bamboo powder were dried in an oven at 80°C for 12 hours. 67 parts by weight of bio-based nylon B1000, 20 parts by weight of bamboo powder, and 13 parts by weight of additives were mixed, added to a mixer, and mixed at 190°C and 100 rpm for 8 minutes. The nylon composite material was then extruded.

[0030] Comparative Example 2 This comparative example provides a nylon composite material, which is prepared according to the following method: Bio-based nylon B1000, bamboo powder, and the amino-terminated polyamide prepared in Example 1 were all dried in an oven at 80°C for 12 hours. 61 parts by weight of bio-based nylon B1000, 20 parts by weight of bamboo powder, 6 parts by weight of amino-terminated polyamide, and 13 parts by weight of additives were mixed and added to a mixer. The mixture was then mixed at 190°C and 100 rpm for 8 minutes, and extruded to obtain the nylon composite material.

[0031] Comparative Example 3 This comparative example provides a nylon composite material, which is prepared according to the following method: Bio-based nylon B1000 and the oxidized bamboo powder prepared in Example 1 were dried in an oven at 80°C for 12 hours. 67 parts by weight of bio-based nylon B1000, 20 parts by weight of oxidized bamboo powder, and 13 parts by weight of additives were mixed and added to a mixer. The mixture was then mixed at 190°C, 100 rpm, and for 8 minutes, and extruded to obtain a nylon composite material.

[0032] Comparative Example 4 This comparative example provides a nylon composite material. The difference between this comparative example and Example 1 is that step S3 is different, as detailed below: 63 parts by weight of bio-based nylon B1000, 20 parts by weight of oxidized bamboo powder, 4 parts by weight of amino-terminated polyamide and 13 parts by weight of additives were mixed and added to an internal mixer. The mixture was then mixed at 190°C and 100 rpm for 8 minutes and extruded to obtain a nylon composite material.

[0033] Comparative Example 5 This comparative example provides a nylon composite material. The difference between this comparative example and Example 1 is that step S3 is different, as detailed below: 57 parts by weight of bio-based nylon B1000, 20 parts by weight of oxidized bamboo powder, 10 parts by weight of amino-terminated polyamide and 13 parts by weight of additives were mixed and added to an internal mixer. The mixture was then mixed at 190°C and 100 rpm for 8 minutes and extruded to obtain a nylon composite material.

[0034] Comparative Example 6 This comparative example provides a nylon composite material. The difference between this comparative example and Example 1 is that step S3 is different, as detailed below: 52 parts by weight of bio-based nylon B1000, 20 parts by weight of oxidized bamboo powder, 15 parts by weight of amino-terminated polyamide and 13 parts by weight of additives were mixed and added to an internal mixer. The mixture was then mixed at 190°C and 100 rpm for 8 minutes and extruded to obtain a nylon composite material.

[0035] Experimental Example The composite materials obtained in Example 1 and Comparative Examples 1-6 were subjected to performance testing, and the specific methods are as follows: The composite material was fabricated into dumbbell-shaped specimens measuring 0.5 mm × 2.0 mm. Tensile tests were performed using a mechanical testing machine, maintaining a length of 10 mm and a tensile rate of 5 mm / min. The stress, strain, and toughness were measured. The test results are as follows: Figure 5 , Figure 6 As shown in Table 1.

[0036] Table 1 Performance test results of composite materials

[0037] Combination Figure 5 , Figure 6 As shown in Table 1, a series of composite materials with different properties can be obtained by controlling the state of bamboo powder and varying the introduction and content of amino-terminated polyamide. Among them, Example 1 exhibits the best overall performance, with a stress of 32.4 MPa, a strain of 39.9%, and a toughness of 10.23 MJ / m. 3 The source of this superior performance can be fully demonstrated through the mechanism analysis of the following comparative examples: In Comparative Example 1, bio-based nylon B1000 and bamboo powder were used as raw materials, but no amino-terminated polyamide was added. There was a weak physical interface bond between the bamboo powder and the bio-based nylon B1000 matrix, resulting in poor overall mechanical properties of the composite material.

[0038] In Comparative Example 2, the raw materials used included bio-based nylon B1000, bamboo powder, and amino-terminated polyamide. The composite material exhibited a stress increase to 36.2 MPa, but a significant decrease in strain and toughness. This is because the bamboo powder was not oxidized and lacked reactive aldehyde groups, preventing the amino-terminated polyamide from forming chemical crosslinks with it. The amino-terminated polyamide merely existed as a free polymer filler in the system, increasing the rigidity of the matrix but hindering the slippage of molecular chains, resulting in significant brittleness in the composite material.

[0039] In Comparative Example 3, bio-based nylon B1000 and oxidized bamboo powder were used as raw materials, without the addition of amino-terminated polyamide. The stress of the composite material reached 30.6 MPa, but the strain was only 17.8%. Although the bamboo powder was oxidized, the lack of amino-terminated polyamide as a flexible bridge in the system prevented the construction of a hierarchical dynamic network structure of "rigid filler-elastic buffer layer-matrix", and the energy-dissipating toughening mechanism of the composite material was missing.

[0040] Example 1 introduced both oxidized bamboo powder and amino-terminated polyamide. The aldehyde groups of the oxidized bamboo powder and the amino groups of the polyamide end groups underwent in-situ condensation at high temperature during mixing, generating dynamic imine bonds (Schiff base network). This strong chemical bonding greatly enhanced the interfacial adhesion, enabling effective stress transfer; at the same time, the flexible segments of the amino-terminated polyamide endowed the composite material with excellent deformation ability, achieving a double leap in strength and toughness.

[0041] With the increase of amino-terminated polyamide content, as shown in Comparative Examples 4-6, the various mechanical properties of the composite materials exhibit a precipitous decline. For example, the stress of the composite material in Comparative Example 5 decreased to 18.3 MPa, and the toughness decreased to 2.73 MJ / m. 3This is because excessive amino-terminated polyamide cannot fully participate in the crosslinking reaction of oxidized bamboo powder, resulting in severe self-agglomeration and phase separation in the bio-based nylon B1000 matrix. This not only disrupts the original continuity and crystallinity of the bio-based nylon B1000 matrix but also becomes a stress concentration defect point within the material, restricting the flow and deformation of polymer chains, leading to a comprehensive deterioration in the mechanical strength and ductility of the composite material.

[0042] In summary, only through the synergistic effect of oxidized bamboo powder and a specific amount of amino-terminated polyamide can a dynamic Schiff base crosslinking network with suitable density be constructed inside the bio-based nylon B1000 matrix, thereby successfully overcoming the brittleness defects of traditional biomass composite materials and achieving high strength and toughness.

[0043] 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 a bamboo fiber reinforced bio-based nylon composite material, characterized in that, Bio-based nylon B1000, oxidized bamboo powder, amino-terminated polyamide and additives are mixed in a mass ratio of 61:20:6:13 and then compounded by intensive mixing to form the bamboo fiber reinforced bio-based nylon composite material. The oxidized bamboo powder contains aldehyde groups, and the structural formula of the amino-terminated polyamide is as follows: ，5≤y≤15。 2. The method for preparing bamboo fiber reinforced bio-based nylon composite material according to claim 1, characterized in that, The mixing temperature is 190~200℃, and the time is 8~10 minutes.

3. The method for preparing bamboo fiber reinforced bio-based nylon composite material according to claim 1, characterized in that, Amino-terminated polyamides are prepared by the following method: The diacid and hexamethylenediamine are obtained by melt polycondensation under a catalyst and nitrogen atmosphere through stepwise heating; the structural formula of the diacid is: .

4. The method for preparing bamboo fiber reinforced bio-based nylon composite material according to claim 3, characterized in that, The molar ratio of dicarboxylic acid, hexamethylenediamine, and catalyst is 50:100:1.5; the catalyst is hypophosphite.

5. The method for preparing bamboo fiber reinforced bio-based nylon composite material according to claim 3, characterized in that, The stepwise heating process is as follows: react at 100℃ for 1 hour, then increase to 140℃ for 1.5 hours, then increase to 160℃ for 1.5 hours, then increase to 190℃ for 3 hours, and finally evacuate to a vacuum. Continue the reaction at 0.09 MPa for 2.5 hours.

6. The method for preparing bamboo fiber reinforced bio-based nylon composite material according to claim 1, characterized in that, Oxidized bamboo powder is prepared by the following method: Bamboo powder is dispersed in water and subjected to oxidation reaction with sodium periodate under light-protected conditions.

7. The method for preparing bamboo fiber reinforced bio-based nylon composite material according to claim 6, characterized in that, The mass ratio of bamboo powder to sodium periodate is 1:

1.

8. The method for preparing bamboo fiber reinforced bio-based nylon composite material according to claim 6, characterized in that, The oxidation temperature is 45~50℃, and the time is 10~12h.

9. The method for preparing bamboo fiber reinforced bio-based nylon composite material according to claim 1, characterized in that, The adjuvant is obtained by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 1:

1.

10. A method for preparing a bamboo fiber reinforced bio-based nylon composite material according to any one of claims 1-9, thereby obtaining the bamboo fiber reinforced bio-based nylon composite material.

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