Bio-based polyamide with excellent mechanical property and preparation method thereof

Abstract

The invention discloses bio-based polyamide with excellent mechanical properties and a preparation method thereof, and belongs to the technical field of polyamide preparation. The bio-based polyamide with excellent mechanical properties is prepared from the following components in parts by weight: 30 to 50 parts of pentamethylene diamine, 10 to 40 parts of bio-based binary acid, 3 to 10 parts of modified diamine, 0.04 to 0.1 part of sodium hypophosphite, 1 to 5 parts of triphenylmethylamine and 1 to 5 parts of modified antioxidant. The bio-based polyamide prepared by the method has excellent mechanical properties, heat-resistant stability and oxidation resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyamide preparation, and in particular relates to a bio-based polyamide with excellent mechanical properties and a preparation method thereof. Background Art

[0002] Amidst the intensifying crisis of fossil energy depletion, bio-based polyamides, a class of polymer materials synthesized from renewable biomass, are becoming a research hotspot in materials science. While the production of traditional petroleum-based polyamides relies on non-renewable resources and produces high carbon emissions, bio-based polyamides, produced using renewable raw materials such as castor oil, glucose, and microbial fermentation products, combined with biological, chemical, and physical methods, not only reduce fossil energy consumption but also offer a potential for energy savings and emissions reductions of 30%-50% through biomanufacturing. However, the industrialization of bio-based polyamides still faces significant challenges, with insufficient mechanical properties being a key bottleneck restricting their widespread application.

[0003] Patent CN116355205B discloses a bio-based polyamide and its preparation method, which introduces 2,5-furandicarboxylic acid with a furan ring structure and bio-based cis-aconitic acid containing three carboxyl functional groups into polyamide, and reacts with decanediamine to obtain an environmentally friendly polyamide with excellent comprehensive performance. The synthesis method of this invention is green, non-toxic, environmentally friendly, and simple to operate. The monomers are derived from biomass resources and the raw materials are widely available. The synthesized bio-based polyamide has more excellent mechanical properties and heat resistance, as well as lower water absorption, higher yield and molecular weight. Although the invention constructs a polyamide system with a unique molecular chain configuration by introducing a furan ring structure and a tricarboxyl bio-based monomer, and shows significant advantages in heat resistance, dimensional stability and processing efficiency, its mechanical properties still have room for optimization. Due to the compatibility balance problem between the rigid tricarboxylic acid structure of cis-aconitic acid and the flexible decanediamine chain segment, the elongation at break and impact toughness of the resulting polymer are somewhat lower than those of traditional petroleum-based polyamides, and its applicability is limited in engineering application scenarios that require high impact resistance or complex stress bearing. Summary of the Invention

[0004] The purpose of the present invention is to provide a bio-based polyamide with excellent mechanical properties and a preparation method thereof, so as to solve the technical problem that the mechanical properties and antioxidant properties of bio-based polyamide in the prior art are poor.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The invention provides a bio-based polyamide with excellent mechanical properties. The bio-based polyamide is composed of the following components in parts by weight: 30-50 parts of pentamethylenediamine, 10-40 parts of bio-based dibasic acid, 3-10 parts of modified diamine, 0.04-0.1 parts of sodium hypophosphite, 1-5 parts of triphenylmethylamine, and 1-5 parts of a modified antioxidant.

[0006] Preferably, the bio-based dibasic acid is composed of one or more of sebacic acid, undecanedioic acid, tridecanedioic acid and hexadecane dibasic acid.

[0007] Preferably, the preparation method of the modified diamine comprises the following steps: Q1: 5-nitro-2-furoic acid and 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added to dichloromethane, followed by the addition of triethylamine, and the reaction was stirred at room temperature. After the reaction was completed, tert-butyl carbazate was added, and the stirring was continued at room temperature. After the stirring was completed, the mixture was washed, dried, filtered, and concentrated under reduced pressure. After separation and purification, the mixture was added to dichloromethane, and trifluoroacetic acid was added. The mixture was stirred at room temperature and concentrated under reduced pressure to obtain an oily substance 1; Q2: Add the oily substance 1 to a mixed solution of water and ethanol, then add anhydrous sodium acetate. After stirring at room temperature, add dropwise an ethanol solution containing p-nitrobenzaldehyde. After the addition is complete, continue stirring at room temperature, filter, and dry to obtain a white solid 2. Q3: Add the white solid 2 to ethyl acetate, followed by sodium iodide and tert-butyl hypochlorite. Stir at room temperature, wash, dry, filter, concentrate under reduced pressure, and purify to obtain a white solid 3. Q4: Under nitrogen protection, the white solid 3 and reduced iron powder were added to a container filled with anhydrous acetic acid, heated and stirred for reaction, cooled, extracted, washed, dried, and purified to obtain a modified diamine.

[0008] In the above process, the synthetic reaction formula of modified diamine is as follows: The results of mass spectrometry analysis of the oily substance 1 were: m / z: 171.03 (100.0%), 172.03 (6.7%), 173.03 (1.0%); the results of mass spectrometry analysis of the white solid 2 were: m / z: 304.04 (100.0%), 305.05 (13.3%), 306.05 (2.1%), 305.04 (1.5%); the results of mass spectrometry analysis of the white solid 3 were: m / z: 302.03 (100.0%), 303.03 (14.7%), 304.03 (1.4%); the results of mass spectrometry analysis of the modified diamine were: m / z: 242.08 (100.0%), 243.08 (14.5%).

[0009] Preferably, in Q1, the dosage ratio of 5-nitro-2-furoic acid, 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, triethylamine, tert-butyl carbazate and trifluoroacetic acid is (1.38-1.76) g: (4.12-5.01) g: (2.98-3.11) g: (1.32-1.84) g: (0.8-1.4) mL, the reaction time is 30-60 min under stirring at room temperature, the stirring time at room temperature is continued for 2-3 h, and the stirring time at room temperature after the addition of trifluoroacetic acid is 60-90 min.

[0010] Preferably, in Q2, the molar ratio of the oil 1, anhydrous sodium acetate and p-nitrobenzaldehyde is (0.8-1.18): (1.42-1.63): (1.05-1.28), the stirring time at room temperature is 5-8 minutes, and the stirring time at room temperature is continued for 1-2 hours.

[0011] Preferably, in Q3, the molar ratio of the white solid 2, sodium iodide, and tert-butyl hypochlorite is (0.9-1.15): (1.13-1.25): (1.43-1.57), and the stirring time at room temperature is 3-4 h; in Q4, the amount ratio of the white solid 3, reduced iron powder, and anhydrous acetic acid is (1.21-1.54) g: (0.8-0.94) g: (8-12) mL.

[0012] Preferably, the preparation method of the modified antioxidant comprises the following steps: S1: Genistein, acetone, and anhydrous potassium carbonate are added to a container, heated to reflux, and then bromoacetophenone is slowly added dropwise. The mixture is heated to reflux for reaction. After the reaction is completed, the mixture is decompressed, distilled water is added to dissolve the mixture, and the pH is adjusted. The mixture is extracted, washed, dried, and purified to obtain a white solid A. S2: Add ethanol, white solid A, sodium acetate trihydrate and hydroxylamine hydrochloride into a container, heat to react, and after the reaction is completed, reduce the pressure, add distilled water, extract, wash, dry, and purify to obtain a modified antioxidant.

[0013] In the above process, the synthetic reaction formula of the modified antioxidant is as follows: The results of mass spectrometry analysis of white solid A were: m / z: 388.09 (100.0%), 389.10 (25.3%), 390.10 (4.3%); the results of mass spectrometry analysis of modified antioxidant were: m / z: 403.11 (100.0%), 404.11 (25.3%), 405.11 (4.3%).

[0014] Preferably, in S1, the dosage ratio of genistein, acetone, anhydrous potassium carbonate and bromoacetophenone is (1-2) g: (20-30) mL: (0.58-0.64) g: (0.81-0.98) g, the heating reflux time is 5-10 min, the heating reflux reaction temperature after the dropwise addition of bromoacetophenone is 60-65° C., the reaction time is 1-1.5 h, and the pH is adjusted to 5-5.4.

[0015] Preferably, in S2, the molar ratio of white solid A, sodium acetate trihydrate and hydroxylamine hydrochloride is (0.45-0.55): (0.42-0.58): (0.55-0.65), the volume fraction of ethanol is 95vt%, the heating reaction temperature is 70-80°C, and the reaction time is 1-2h.

[0016] Preferably, the method for preparing the bio-based polyamide with excellent mechanical properties comprises the following steps: Step 1: Add pentamethylenediamine, bio-based dibasic acid and modified diamine into a reactor, add deionized water, introduce nitrogen, heat and stir to react, and obtain a salt solution; Step 2: adding sodium hypophosphite and triphenylmethylamine to the salt solution to undergo polycondensation reaction to obtain a mixture; Step 3: Cool the mixture, extrude and granulate it, then add the modified antioxidant, mix it evenly, and dry it to obtain a bio-based polyamide with excellent mechanical properties.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention first adds modified diamine and modified antioxidant during the preparation process of bio-based polyamide, which can effectively improve its mechanical properties, thermal stability and antioxidant properties.

[0018] 2. In the process of preparing bio-based polyamide, the present invention adds modified diamine, which can effectively improve its mechanical properties and thermal stability. The rigid ring structure contained in the modified diamine can enhance the rigidity of the molecular chain, reduce deformation, promote crystallization, and improve tensile strength and modulus. The rigid ring structure can also reduce the thermal motion of the molecular chain and reduce the degradation rate, so that the bio-based polyamide can still maintain stable performance at high temperatures.

[0019] 3. The present invention adds a modified antioxidant to the preparation process of bio-based polyamide, which can effectively improve its antioxidant performance, mechanical properties and thermal stability. The oxime group contained in the modified antioxidant can interrupt the oxidation chain reaction by capturing free radicals through nitrogen atoms, and the phenolic hydroxyl group stabilizes the free radicals through hydrogen atom transfer. At the same time, the conjugated system in genistein quenches excited oxygen molecules through electron transfer; and the modified antioxidant can also enhance thermal stability, not only by slowing down the chain reaction by capturing thermal degradation free radicals, but also by reducing thermal motion bond breaking through the hydrogen bonding effect of the oxime group and the amide bond; in addition, the hydrogen bonding between the oxime group and the polar group enhances the interface compatibility, reduces stress concentration, and simultaneously improves the tensile strength and mechanical properties. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] Example 1: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: 1.57 g of 5-nitro-2-furoic acid and 4.56 g of 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added to 5 mL of dichloromethane, followed by the addition of 3.04 g of triethylamine. The mixture was stirred at room temperature for 60 min. After the reaction, 1.53 g of tert-butyl carbazate was added and the mixture was stirred at room temperature for 2 h. After the stirring was completed, the mixture was washed, dried, filtered, and concentrated under reduced pressure. After separation and purification, the mixture was added to 5 mL of dichloromethane, and then 1.1 mL of trifluoroacetic acid was added. The mixture was stirred at room temperature for 60 min and concentrated under reduced pressure to obtain an oily substance 1; Q2: 1.62 g of oily substance 1 was added to a mixed solution of 2.5 mL of water and 2.5 mL of ethanol, followed by 1.25 g of anhydrous sodium acetate. After stirring at room temperature for 8 min, 10 mL of an ethanol solution containing 1.71 g of p-nitrobenzaldehyde was added dropwise. After the addition was complete, stirring was continued at room temperature for 1 h, filtered, and dried to obtain a white solid 2. Q3: 2.85 g of white solid 2 was added to 5 mL of ethyl acetate, followed by 1.78 g of sodium iodide and 1.62 g of tert-butyl hypochlorite. The mixture was stirred at room temperature for 4 h, washed, dried, filtered, concentrated under reduced pressure, and purified to obtain a white solid 3. Q4: Under nitrogen protection, 1.37 g of white solid 3 and 0.87 g of reduced iron powder were added to a container containing 10 mL of anhydrous acetic acid, and the mixture was heated and stirred for reaction. The mixture was cooled, extracted, washed, dried, and purified to obtain a modified diamine.

[0022] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: 1.5 g of genistein, 25 mL of acetone, and 0.62 g of anhydrous potassium carbonate were added to a container, heated under reflux for 5 min, and then 0.91 g of bromoacetophenone was slowly added dropwise. The mixture was heated under reflux at 60°C for 1 h. After the reaction, the mixture was decompressed, dissolved in distilled water, and the pH was adjusted to 5. The mixture was extracted, washed, dried, and purified to obtain a white solid A. S2: Add 15 mL of 95% by volume ethanol, 1.935 g of white solid A, 0.675 g of sodium acetate trihydrate and 0.414 g of hydroxylamine hydrochloride into a container, heat at 75°C for 2 h, and after the reaction is completed, decompress the mixture, add distilled water, extract, wash, dry and purify to obtain a modified antioxidant.

[0023] This embodiment discloses a bio-based polyamide with excellent mechanical properties, which is composed of the following components in parts by weight: 40 parts of pentamethylenediamine, 25 parts of sebacic acid, 6.5 parts of modified diamine, 0.07 parts of sodium hypophosphite, 3 parts of triphenylmethane, and 3 parts of modified antioxidant.

[0024] This embodiment discloses a method for preparing a bio-based polyamide with excellent mechanical properties, comprising the following steps: Step 1: Add pentamethylenediamine, sebacic acid and modified diamine into a reaction kettle, add deionized water, introduce nitrogen, heat to 100°C and stir for 2 hours to obtain a salt solution; Step 2: adding sodium hypophosphite and triphenylamine to the salt solution, and carrying out polycondensation reaction at 220° C. and 2 MPa for 4 h to obtain a mixture; Step 3: Cool the mixture to 200°C, extrude and granulate, then add the modified antioxidant, mix evenly, and dry at 80°C for 4 hours to obtain a bio-based polyamide with excellent mechanical properties.

[0025] Example 2: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: 1.38 g of 5-nitro-2-furoic acid and 4.12 g of 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added to 5 mL of dichloromethane, followed by the addition of 2.98 g of triethylamine. The mixture was stirred at room temperature for 60 min. After the reaction, 1.32 g of tert-butyl carbazate was added and the mixture was stirred at room temperature for 2 h. After the stirring was completed, the mixture was washed, dried, filtered, and concentrated under reduced pressure. After separation and purification, the mixture was added to 5 mL of dichloromethane, and then 0.8 mL of trifluoroacetic acid was added. The mixture was stirred at room temperature for 60 min and concentrated under reduced pressure to obtain an oily substance 1. Q2: 1.37 g of oily substance 1 was added to a mixed solution of 2.5 mL of water and 2.5 mL of ethanol, followed by 1.16 g of anhydrous sodium acetate. After stirring at room temperature for 8 min, 10 mL of an ethanol solution containing 1.59 g of p-nitrobenzaldehyde was added dropwise. After the addition was complete, stirring was continued at room temperature for 1 h, filtered, and dried to obtain a white solid 2. Q3: 2.59 g of white solid 2 was added to 5 mL of ethyl acetate, followed by 1.69 g of sodium iodide and 1.55 g of tert-butyl hypochlorite. The mixture was stirred at room temperature for 4 h, washed, dried, filtered, concentrated under reduced pressure, and purified to obtain a white solid 3. Q4: Under nitrogen protection, 1.21 g of white solid 3 and 0.8 g of reduced iron powder were added to a container containing 8 mL of anhydrous acetic acid, and the mixture was heated and stirred for reaction. The mixture was cooled, extracted, washed, dried, and purified to obtain a modified diamine.

[0026] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: 1 g of genistein, 30 mL of acetone, and 0.58 g of anhydrous potassium carbonate were added to a container, heated under reflux for 5 min, and then 0.81 g of bromoacetophenone was slowly added dropwise. The mixture was heated under reflux at 60°C for 1 h. After the reaction, the mixture was decompressed, dissolved in distilled water, and the pH was adjusted to 5. The mixture was extracted, washed, dried, and purified to obtain a white solid A. S2: Add 15 mL of 95% by volume ethanol, 1.746 g of white solid A, 0.571 g of sodium acetate trihydrate and 0.38 g of hydroxylamine hydrochloride into a container, heat at 75°C for 2 h, and after the reaction is completed, reduce the pressure, add distilled water, extract, wash, dry and purify to obtain a modified antioxidant.

[0027] This embodiment discloses a bio-based polyamide with excellent mechanical properties, which is composed of the following components in parts by weight: 30 parts of pentamethylenediamine, 10 parts of sebacic acid, 3 parts of modified diamine, 0.1 parts of sodium hypophosphite, 5 parts of triphenylmethane, and 1 part of modified antioxidant.

[0028] This embodiment discloses a method for preparing a bio-based polyamide with excellent mechanical properties, comprising the following steps: Step 1: Add pentamethylenediamine, sebacic acid and modified diamine into a reaction kettle, add deionized water, introduce nitrogen, heat to 100°C and stir for 2 hours to obtain a salt solution; Step 2: adding sodium hypophosphite and triphenylamine to the salt solution, and carrying out polycondensation reaction at 220° C. and 2 MPa for 4 h to obtain a mixture; Step 3: Cool the mixture to 200°C, extrude and granulate, then add the modified antioxidant, mix evenly, and dry at 80°C for 4 hours to obtain a bio-based polyamide with excellent mechanical properties.

[0029] Example 3: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: 1.76 g of 5-nitro-2-furoic acid and 5.01 g of 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added to 5 mL of dichloromethane, followed by the addition of 3.11 g of triethylamine. The mixture was stirred at room temperature for 60 min. After the reaction, 1.84 g of tert-butyl carbazate was added and the mixture was stirred at room temperature for 2 h. After the stirring was completed, the mixture was washed, dried, filtered, and concentrated under reduced pressure. After separation and purification, the mixture was added to 5 mL of dichloromethane, and then 1.4 mL of trifluoroacetic acid was added. The mixture was stirred at room temperature for 60 min and concentrated under reduced pressure to obtain an oily substance 1. Q2: Add 2.02 g of oily substance 1 to a mixed solution of 2.5 mL of water and 2.5 mL of ethanol, then add 1.34 g of anhydrous sodium acetate. After stirring at room temperature for 8 min, add dropwise 10 mL of an ethanol solution containing 1.93 g of p-nitrobenzaldehyde. After the addition is complete, continue stirring at room temperature for 1 h, filter, and dry to obtain a white solid 2. Q3: 3.31 g of white solid 2 was added to 5 mL of ethyl acetate, followed by 1.87 g of sodium iodide and 1.7 g of tert-butyl hypochlorite. The mixture was stirred at room temperature for 4 h, washed, dried, filtered, concentrated under reduced pressure, and purified to obtain a white solid 3. Q4: Under nitrogen protection, 1.54 g of white solid 3 and 0.94 g of reduced iron powder were added to a container containing 12 mL of anhydrous acetic acid, and the mixture was heated and stirred for reaction. The mixture was cooled, extracted, washed, dried, and purified to obtain a modified diamine.

[0030] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: 2 g of genistein, 20 mL of acetone, and 0.64 g of anhydrous potassium carbonate were added to a container, heated under reflux for 5 min, and then 0.98 g of bromoacetophenone was slowly added dropwise. The mixture was heated under reflux at 60°C for 1 h. After the reaction, the mixture was decompressed, dissolved in distilled water, and the pH was adjusted to 5. The mixture was extracted, washed, dried, and purified to obtain a white solid A. S2: Add 15 mL of 95% by volume ethanol, 2.134 g of white solid A, 0.789 g of sodium acetate trihydrate and 0.449 g of hydroxylamine hydrochloride into a container, heat at 75°C for 2 h, and after the reaction is completed, reduce the pressure, add distilled water, extract, wash, dry and purify to obtain a modified antioxidant.

[0031] This embodiment discloses a bio-based polyamide with excellent mechanical properties, which is composed of the following components in parts by weight: 50 parts of pentamethylenediamine, 40 parts of sebacic acid, 10 parts of modified diamine, 0.04 parts of sodium hypophosphite, 1 part of triphenylmethane, and 5 parts of modified antioxidant.

[0032] This embodiment discloses a method for preparing a bio-based polyamide with excellent mechanical properties, comprising the following steps: Step 1: Add pentamethylenediamine, sebacic acid and modified diamine into a reaction kettle, add deionized water, introduce nitrogen, heat to 100°C and stir for 2 hours to obtain a salt solution; Step 2: adding sodium hypophosphite and triphenylamine to the salt solution, and carrying out polycondensation reaction at 220° C. and 2 MPa for 4 h to obtain a mixture; Step 3: Cool the mixture to 200°C, extrude and granulate, then add the modified antioxidant, mix evenly, and dry at 80°C for 4 hours to obtain a bio-based polyamide with excellent mechanical properties.

[0033] Example 4: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: 1.47 g of 5-nitro-2-furoic acid and 4.34 g of 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added to 5 mL of dichloromethane, followed by the addition of 3.01 g of triethylamine. The mixture was stirred at room temperature for 60 min. After the reaction, 1.42 g of tert-butyl carbazate was added and the mixture was stirred at room temperature for 2 h. After the stirring was completed, the mixture was washed, dried, filtered, and concentrated under reduced pressure. After separation and purification, the mixture was added to 5 mL of dichloromethane, and then 1.2 mL of trifluoroacetic acid was added. The mixture was stirred at room temperature for 60 min and concentrated under reduced pressure to obtain an oily substance 1; Q2: Add 1.48 g of oily substance 1 to a mixed solution of 2.5 mL of water and 2.5 mL of ethanol, then add 1.18 g of anhydrous sodium acetate. After stirring at room temperature for 8 min, add dropwise 10 mL of an ethanol solution containing 1.62 g of p-nitrobenzaldehyde. After the addition is complete, continue stirring at room temperature for 1 h, filter, and dry to obtain a white solid 2. Q3: 2.62 g of white solid 2 was added to 5 mL of ethyl acetate, followed by 1.72 g of sodium iodide and 1.58 g of tert-butyl hypochlorite. The mixture was stirred at room temperature for 4 h, washed, dried, filtered, concentrated under reduced pressure, and purified to obtain a white solid 3. Q4: Under nitrogen protection, 1.28 g of white solid 3 and 0.81 g of reduced iron powder were added to a container containing 9 mL of anhydrous acetic acid, and the mixture was heated and stirred for reaction. The mixture was cooled, extracted, washed, dried, and purified to obtain a modified diamine.

[0034] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: 1.1 g of genistein, 22 mL of acetone, and 0.59 g of anhydrous potassium carbonate were added to a container, heated under reflux for 5 min, and then 0.86 g of bromoacetophenone was slowly added dropwise. The mixture was heated under reflux at 60°C for 1 h. After the reaction, the mixture was decompressed, dissolved in distilled water, and the pH was adjusted to 5. The mixture was extracted, washed, dried, and purified to obtain a white solid A. S2: Add 15 mL of 95% by volume ethanol, 1.812 g of white solid A, 0.593 g of sodium acetate trihydrate and 0.395 g of hydroxylamine hydrochloride into a container, heat at 75°C for 2 h, and after the reaction is completed, reduce the pressure, add distilled water, extract, wash, dry and purify to obtain a modified antioxidant.

[0035] This embodiment discloses a bio-based polyamide with excellent mechanical properties, which is composed of the following components in parts by weight: 35 parts of pentamethylenediamine, 15 parts of sebacic acid, 5 parts of modified diamine, 0.06 parts of sodium hypophosphite, 2 parts of triphenylmethane, and 4 parts of modified antioxidant.

[0036] This embodiment discloses a method for preparing a bio-based polyamide with excellent mechanical properties, comprising the following steps: Step 1: Add pentamethylenediamine, sebacic acid and modified diamine into a reaction kettle, add deionized water, introduce nitrogen, heat to 100°C and stir for 2 hours to obtain a salt solution; Step 2: adding sodium hypophosphite and triphenylamine to the salt solution, and carrying out polycondensation reaction at 220° C. and 2 MPa for 4 h to obtain a mixture; Step 3: Cool the mixture to 200°C, extrude and granulate, then add the modified antioxidant, mix evenly, and dry at 80°C for 4 hours to obtain a bio-based polyamide with excellent mechanical properties.

[0037] Comparative Example 5: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: 1.62 g of 5-nitro-2-furoic acid and 4.87 g of 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added to 5 mL of dichloromethane, followed by the addition of 3.07 g of triethylamine. The mixture was stirred at room temperature for 60 min. After the reaction, 1.71 g of tert-butyl carbazate was added and the mixture was stirred at room temperature for 2 h. After the stirring was completed, the mixture was washed, dried, filtered, and concentrated under reduced pressure. After separation and purification, the mixture was added to 5 mL of dichloromethane, and then 0.9 mL of trifluoroacetic acid was added. The mixture was stirred at room temperature for 60 min and concentrated under reduced pressure to obtain an oily substance 1. Q2: 1.95 g of oily substance 1 was added to a mixed solution of 2.5 mL of water and 2.5 mL of ethanol, followed by 1.32 g of anhydrous sodium acetate. After stirring at room temperature for 8 min, 10 mL of an ethanol solution containing 1.87 g of p-nitrobenzaldehyde was added dropwise. After the addition was complete, stirring was continued at room temperature for 1 h, filtered, and dried to obtain a white solid 2. Q3: 3.11 g of white solid 2 was added to 5 mL of ethyl acetate, followed by 1.83 g of sodium iodide and 1.68 g of tert-butyl hypochlorite. The mixture was stirred at room temperature for 4 h, washed, dried, filtered, concentrated under reduced pressure, and purified to obtain a white solid 3. Q4: Under nitrogen protection, 1.47 g of white solid 3 and 0.93 g of reduced iron powder were added to a container containing 11 mL of anhydrous acetic acid, and the mixture was heated and stirred for reaction. The mixture was cooled, extracted, washed, dried, and purified to obtain a modified diamine.

[0038] This embodiment discloses a method for preparing a modified antioxidant, comprising the following steps: S1: 1.8 g of genistein, 28 mL of acetone, and 0.63 g of anhydrous potassium carbonate were added to a container, heated under reflux for 5 min, and then 0.93 g of bromoacetophenone was slowly added dropwise. The mixture was heated under reflux at 60°C for 1 h. After the reaction, the mixture was decompressed, dissolved in distilled water, and the pH was adjusted to 5. The mixture was extracted, washed, dried, and purified to obtain a white solid A. S2: Add 15 mL of 95% by volume ethanol, 2.017 g of white solid A, 0.721 g of sodium acetate trihydrate and 0.432 g of hydroxylamine hydrochloride into a container, heat at 75°C for 2 h, and after the reaction is completed, decompress the mixture, add distilled water, extract, wash, dry and purify to obtain a modified antioxidant.

[0039] This embodiment discloses a bio-based polyamide with excellent mechanical properties, which is composed of the following components in parts by weight: 45 parts of pentamethylenediamine, 35 parts of sebacic acid, 8 parts of modified diamine, 0.08 parts of sodium hypophosphite, 4 parts of triphenylmethane, and 2 parts of modified antioxidant.

[0040] This embodiment discloses a method for preparing a bio-based polyamide with excellent mechanical properties, comprising the following steps: Step 1: Add pentamethylenediamine, sebacic acid and modified diamine into a reaction kettle, add deionized water, introduce nitrogen, heat to 100°C and stir for 2 hours to obtain a salt solution; Step 2: adding sodium hypophosphite and triphenylamine to the salt solution, and carrying out polycondensation reaction at 220° C. and 2 MPa for 4 h to obtain a mixture; Step 3: Cool the mixture to 200°C, extrude and granulate, then add the modified antioxidant, mix evenly, and dry at 80°C for 4 hours to obtain a bio-based polyamide with excellent mechanical properties.

[0041] Comparative Example 1: Compared with Example 1, in Comparative Example 1, no modified diamine was added during the preparation of the bio-based polyamide, and other conditions remained unchanged.

[0042] Comparative Example 2: Compared with Example 1, in Comparative Example 2, during the preparation of bio-based polyamide, no modified antioxidant was added, and other conditions remained unchanged.

[0043] Performance Testing The bio-based polyamides prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to performance tests. The tensile properties of the samples were tested according to GB / T 1040.2-2022, the thermal stability of the samples was tested according to GB / T 1634.2-2019, and the yellowing resistance of the samples was tested according to HG / T 3862-2006. The test results are shown in Table 1: Table 1 It can be seen from the test results in Table 1 that by using the methods of Examples 1-5, the mechanical properties, thermal stability and antioxidant properties of bio-based polyamide can be effectively improved. The tensile strength data show that the tensile strength of the samples prepared in Examples 1-5 is significantly higher than that in Comparative Example 1, indicating that the addition of modified diamine can effectively improve the mechanical properties of bio-based polyamide. The tensile strength of the samples prepared in Examples 1-5 is significantly higher than that in Comparative Example 2, indicating that the addition of modified antioxidants can effectively improve the mechanical properties of bio-based polyamide. The flexural strength reduction rate indicates the change in the flexural strength of the sample before and after the thermal stability test. The lower the flexural strength reduction rate, the better the thermal stability of the sample. The flexural strength reduction rates of the comparative example and comparative example 2 are both higher than those of Examples 1-5, indicating that the introduction of modified diamines and the addition of modified antioxidants can effectively improve the thermal stability of the sample. The yellowness index refers to the degree to which the polymer material deviates from white, or the degree of yellowing. The higher the yellowness index difference, the worse the yellowing resistance of the sample, and further the worse the antioxidant performance of the sample. By comparing Comparative Example 2 with Examples 1-5, it can be found that the addition of modified antioxidants can effectively improve the antioxidant performance of the sample.

[0044] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

[0045] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. Bio-based polyamide with excellent mechanical properties, characterized in that: The invention is composed of the following components in parts by weight: 30-50 parts of pentamethylenediamine, 10-40 parts of bio-based dibasic acid, 3-10 parts of modified diamine, 0.04-0.1 parts of sodium hypophosphite, 1-5 parts of triphenylmethylamine and 1-5 parts of modified antioxidant.

2. The bio-based polyamide with excellent mechanical properties according to claim 1, characterized in that: The bio-based dibasic acid is composed of one or more of sebacic acid, undecanedioic acid, tridecanedioic acid and hexadecane dibasic acid.

3. The bio-based polyamide with excellent mechanical properties according to claim 1, characterized in that: The preparation method of the modified diamine comprises the following steps: Q1: 5-nitro-2-furoic acid and 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate were added to dichloromethane, followed by the addition of triethylamine, and the reaction was stirred at room temperature. After the reaction was completed, tert-butyl carbazate was added, and the stirring was continued at room temperature. After the stirring was completed, the mixture was washed, dried, filtered, and concentrated under reduced pressure. After separation and purification, the mixture was added to dichloromethane, and trifluoroacetic acid was added. The mixture was stirred at room temperature and concentrated under reduced pressure to obtain an oily substance 1; Q2: Add the oily substance 1 to a mixed solution of water and ethanol, then add anhydrous sodium acetate. After stirring at room temperature, add dropwise an ethanol solution containing p-nitrobenzaldehyde. After the addition is complete, continue stirring at room temperature, filter, and dry to obtain a white solid 2. Q3: Add the white solid 2 to ethyl acetate, followed by sodium iodide and tert-butyl hypochlorite. Stir at room temperature, wash, dry, filter, concentrate under reduced pressure, and purify to obtain a white solid 3. Q4: Under nitrogen protection, the white solid 3 and reduced iron powder were added to a container filled with anhydrous acetic acid, heated and stirred for reaction, cooled, extracted, washed, dried, and purified to obtain a modified diamine.

4. The bio-based polyamide with excellent mechanical properties according to claim 3, characterized in that: In Q1, the usage ratio of 5-nitro-2-furoic acid, 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, triethylamine, tert-butyl carbazate and trifluoroacetic acid is (1.38-1.76) g: (4.12-5.01) g: (2.98-3.11) g: (1.32-1.84) g: (0.8-1.4) mL.

5. The bio-based polyamide with excellent mechanical properties according to claim 3, characterized in that: In Q2, the molar ratio of the oily substance 1, anhydrous sodium acetate and p-nitrobenzaldehyde is (0.8-1.18): (1.42-1.63): (1.05-1.28).

6. The bio-based polyamide with excellent mechanical properties according to claim 3, characterized in that: In the Q3, the molar ratio of the white solid 2, sodium iodide and tert-butyl hypochlorite is (0.9-1.15): (1.13-1.25): (1.43-1.57); in the Q4, the amount ratio of the white solid 3, reduced iron powder and anhydrous acetic acid is (1.21-1.54) g: (0.8-0.94) g: (8-12) mL.

7. The bio-based polyamide with excellent mechanical properties according to claim 1, characterized in that: The preparation method of the modified antioxidant comprises the following steps: S1: Genistein, acetone, and anhydrous potassium carbonate are added to a container, heated to reflux, and then bromoacetophenone is slowly added dropwise. The mixture is heated to reflux for reaction. After the reaction is completed, the mixture is decompressed, distilled water is added to dissolve the mixture, and the pH is adjusted. The mixture is extracted, washed, dried, and purified to obtain a white solid A. S2: Add ethanol, white solid A, sodium acetate trihydrate and hydroxylamine hydrochloride into a container, heat to react, and after the reaction is completed, reduce the pressure, add distilled water, extract, wash, dry, and purify to obtain a modified antioxidant.

8. The bio-based polyamide with excellent mechanical properties according to claim 7, characterized in that: In the S1, the usage ratio of genistein, acetone, anhydrous potassium carbonate and bromoacetophenone is (1-2) g: (20-30) mL: (0.58-0.64) g: (0.81-0.98) g.

9. The bio-based polyamide with excellent mechanical properties according to claim 7, characterized in that: In the S2, the molar ratio of the white solid A, sodium acetate trihydrate and hydroxylamine hydrochloride is (0.45-0.55): (0.42-0.58): (0.55-0.65).

10. The method for preparing a bio-based polyamide with excellent mechanical properties according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Add pentamethylenediamine, bio-based dibasic acid and modified diamine into a reactor, add deionized water, introduce nitrogen, heat and stir to react, and obtain a salt solution; Step 2: adding sodium hypophosphite and triphenylmethylamine to the salt solution to undergo polycondensation reaction to obtain a mixture; Step 3: Cool the mixture, extrude and granulate it, then add the modified antioxidant, mix it evenly, and dry it to obtain a bio-based polyamide with excellent mechanical properties.

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