Multi-effect modified biodegradable composite material and preparation method thereof

Abstract

The invention discloses a multi-effect modified biodegradable composite material and a preparation method thereof. Relates to a biodegradable material and a preparation method thereof. The modified PLA / PBS composite material comprises the following raw materials: 30-90 parts of polylactic acid (PLA); 10 to 70 parts of poly (butylene succinate) (PBS); 1-10 parts of an environment-friendly auxiliary agent; and 0.1 to 0.5 part of an antioxidant. And drying the raw materials, and carrying out twin-screw extrusion melt blending. Infrared spectrum characteristic analysis, a nuclear magnetic resonance hydrogen spectrum test and a swelling rate test show that the compatibility between the materials is improved by introducing the auxiliary agent, the notch impact strength and the elongation at break of the material are respectively improved to 5178.1 J / m and 247.93% on the basis of keeping high rigidity, and are respectively improved by 184% and 103% compared with those of an unmodified system, meanwhile, the light transmittance is kept unchanged, the haze is reduced by 28.3%, and the material has a good application prospect. The excellent hydrophobicity is realized. The composite material can be completely biodegraded, is suitable for the fields of environment-friendly packaging, disposable products and the like, and has the characteristics of high performance and eco-friendliness.

Description

Technical Field

[0001] The present invention relates to a biodegradable material and a preparation method thereof, and in particular to a multi-effect modified biodegradable composite material and a preparation method thereof. Background Art

[0002] Amidst growing global environmental awareness and a strong emphasis on sustainable development, the research and application of biodegradable materials has become a hot topic in polymer materials science. Polylactic acid (PLA), a bioplastic derived from renewable resources, is highly sought after for its excellent mechanical properties, excellent processing characteristics, and complete biodegradability. However, pure PLA suffers from high brittleness and low elongation at break, which to some extent limits its application. Polybutylene succinate (PBS), a thermoplastic with excellent flexibility and good biodegradability, naturally decomposes into water and carbon dioxide, making it a theoretically ideal choice for improving PLA's toughness. However, the poor compatibility between PLA and PBS leads to insufficient interfacial adhesion in the composite material, which in turn affects the mechanical properties of the final product. To address these challenges, the present invention proposes an innovative preparation method that significantly improves the compatibility between PLA and PBS by adding a specific proportion of environmentally friendly additives. This method also ensures that the resulting composite material exhibits excellent overall properties, including, but not limited to, significantly enhanced notched impact strength and elongation at break, while maintaining good tensile strength and optical properties. This method not only addresses the environmental concerns that traditional compatibilizers may pose, but also avoids negative impacts on the physical properties of composite materials. Furthermore, the production process provided by the present invention is simple, cost-effective, and suitable for large-scale industrial production, meeting the growing market demand for high-performance, environmentally friendly biodegradable materials, thereby promoting the development of a circular economy and contributing to environmental protection.

[0003] The invention patent application, patent number CN 114702775 A, discloses a durable PLA composite with multiple barrier properties and its preparation method. The composite utilizes activated grafting technology to improve the compatibility of PLA and PBS resin, and two additives to enhance the material's strength, rigidity, heat resistance, antibacterial properties, and barrier properties. However, the resulting composite exhibited only a 21.5% elongation at break before degradation, indicating low flexibility.

[0004] The invention patent application with the patent number CN 118772393 A discloses a biodegradable PLA / PBS composite material modified with dicyclohexylmethane isocyanate and a preparation method thereof. Dicyclohexylmethane isocyanate is introduced into the PLA / PBS system to improve the performance of the composite material. However, the elongation at break of the resulting composite material is only 108.6%, which is not significantly improved compared to the 102.32% of the unmodified composite material.

[0005] In contrast, the present invention specifically uses an environmentally friendly compatibilizer to enhance the interfacial compatibility between the PLA and PBS blends. By adding this specific compatibilizer, the material significantly improves notched impact strength and elongation at break while maintaining high rigidity. Meanwhile, the light transmittance remains stable at 89%, the haze is reduced to 37.5%, and excellent hydrophobicity is achieved. Summary of the Invention

[0006] This invention aims to address the issues of poor mechanical strength, optical clarity, thermal stability, and processing fluidity inherent in PLA / PBS composites due to poor compatibility. It proposes a modification scheme and manufacturing process for a PLA / PBS biodegradable polymer system. By introducing an environmentally friendly additive, the interfacial interaction between the PLA and PBS components is effectively enhanced, significantly improving the overall performance of the composite.

[0007] The purpose of the present invention is achieved through the following technical solutions: A multi-effect modified biodegradable composite material, the modified PLA-based composite material comprises the following raw materials: 30-90 parts of polylactic acid; 10-70 parts of polybutylene succinate; 1-10 parts of environmentally friendly additives; 0.1-0.5 parts of antioxidant.

[0008] The multi-effect modified biodegradable composite material, wherein the environmentally friendly additive is one or more of styrene-glycidyl methacrylate (ADR), polyhydroxyalkanoate (PHA), end-epoxy branched polymer (ETBP), and epoxy-functionalized styrene-acrylic acid copolymer (ESA).

[0009] The multi-effect modified biodegradable composite material, wherein the antioxidant is one or more of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and 2,6-di-tert-butyl-4-methylphenol.

[0010] A multi-effect modified biodegradable composite material and a preparation method thereof, the preparation method comprising the following preparation process: PLA and PBS were placed in a vacuum drying oven and dried at 60°C for 12 h to remove moisture. They were then added to a twin-screw extruder for melt blending to prepare bio-based composite materials. The temperatures of zones I, II, III, IV, V, VI and the die head of the extruder were 165°C, 175°C, 175°C, 175°C, 175°C, 175°C and 160°C, respectively. The screw speed was 70 r / min and the feeding rate was 8.0 r / min.

[0011] The advantages and effects of the present invention are: 1. The present invention effectively enhances the intermolecular interaction between PLA and PBS by introducing an environmentally friendly compatibilizer. The resulting composite material exhibits significant improvements in notched impact strength and elongation at break, and possesses superior toughness compared to unmodified PLA / PBS composites while maintaining the inherent rigidity of the material. Furthermore, the composite material exhibits excellent light transmittance and superior hydrophobicity. These improvements provide a solid foundation for expanding the practical applicability of PLA materials and promote their potential application in more fields.

[0012] 2. The present invention uses a biodegradable polymer as a substrate, resulting in a material that is not only completely biodegradable but also exhibits significant environmental and non-toxic properties. Once discarded, this biodegradable plastic can be disposed of through biodegradation methods such as composting or landfill, conforming to the principles of green ecological design and significantly contributing to mitigating environmental issues caused by disposable plastic products. The development and application of this material strictly adheres to the principles of green environmental protection and sustainable development, providing an effective solution for reducing plastic pollution and protecting the natural environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 FTIR spectrum of the blended material of the present invention; Figure 2 H NMR spectrum of the blended material of the present invention; Figure 3 DSC spectrum of the blended material of the present invention; DETAILED DESCRIPTION

[0014] The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings. It should be noted that these embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Those skilled in the art may make non-essential improvements and adjustments to the present invention without departing from the basic principles of the present invention, and such improvements and adjustments should also be considered part of the scope of protection of the present invention.

[0015] Examples 1-5 are examples of the present invention, and the present invention will be described in detail below with reference to the examples.

[0016] Comparative Example 1 80 parts of polylactic acid; 20 parts of polybutylene succinate; 0.1 part antioxidant.

[0017] (1) PLA and PBS were placed in a vacuum drying oven according to the number of materials, dried at 60°C for 12 h to fully dry and remove moisture, and then added into a twin-screw extruder for melt blending to prepare a bio-based composite material. The temperatures of Zone I, Zone II, Zone III, Zone IV, Zone V, Zone VI and the die head of the extruder were 165°C, 175°C, 175°C, 175°C, 175°C, 160°C, respectively. The screw speed was 70 r / min and the feeding rate was 8.0 r / min.

[0018] (2) The blend sample was preheated at 175°C using a flat plate vulcanizer. After the blend melted, it was hot pressed for 6 minutes. After that, it was cold pressed for 6 minutes in another instrument to obtain a blend film. FTIR analysis was then performed. The test range was 4000-600 cm -1 , with a resolution of 0.5cm -1 , wave number accuracy is 0.01cm -1 , the scanning frequency is 75 times / second.

[0019] (3) Weigh approximately 15 mg of the purified and dried PLA / PBS blend and a 3% ESA PLA / PBS / ESA blend. Analyze and test using a nuclear magnetic resonance spectrometer with 128 scans using deuterated chloroform and tetramethylsilane (TMS) as the solvent and internal standard, respectively.

[0020] (4) Prepare a certain mass of dry sample and weigh it. Record the initial mass of the sample and place the sample in the ethanol solvent to ensure that the sample is completely immersed. Let the sample soak in the solvent (ethanol) for 72 hours to achieve swelling equilibrium. Then, after a predetermined time, remove the sample and remove excess liquid. Use filter paper to gently remove excess liquid on the surface. Record the wet mass of the sample after soaking and calculate the swelling rate of the sample ( S r ).

[0021] (5) The thermal properties of the blends were studied using a differential scanning calorimeter under a nitrogen atmosphere. About 5-8 mg of sample was placed in a crucible for sample preparation. After sample preparation, the crucible was placed in the instrument and the temperature was increased from 25°C to 200°C at a rate of 10°C / min. The temperature was then maintained constant for 5 minutes. The temperature was then lowered to 0°C at the same rate of 10°C / min, maintained constant for another 5 minutes, and finally increased to 200°C at the same rate of 10°C / min.

[0022] (6) The prepared samples were molded into standard specimens for tensile and impact tests in a WZS10D micro-injection molding machine at a barrel temperature of 175°C, a mold temperature of 40°C, and a holding time of 10 seconds. The excess parts were trimmed. Subsequently, the specimens were subjected to a tensile test at a rate of 20 mm / min in accordance with GB / T 1040.2-2022 / 1BA to determine their tensile strength and elongation at break. At the same time, the specimens were subjected to an impact test using a 150° pendulum initial angle and an initial potential energy of 2.750 J in accordance with GB / T 1843-2008 / A to determine their impact strength.

[0023] (7) The prepared composite material particles were pressed into a film about 80 μm thick using a flat vulcanizer at a pressure of 10 MPa, and then the transmittance was tested using a haze meter.

[0024] (8) The contact angle of the blend was measured using an angular contact meter. A 1 μL sessile water droplet was deposited on the surface of the prepared sample by a syringe pump, and the contact angle value was extracted from the recorded droplet image using software based on an ellipse model. To obtain the average value, five droplets were deposited at different locations on the sample. The surface of the test sample was evaluated by measuring the contact angles of distilled water and diiodomethane. The adhesion work (W) of the sample was evaluated based on the contact angle value. α ) and surface energy (γ). Example 1

[0025] 80 parts of polylactic acid; 20 parts of polybutylene succinate; 1 part of epoxy-functionalized styrene-acrylic acid copolymer; 0.1 part antioxidant.

[0026] (1) PLA and PBS were placed in a vacuum drying oven according to the number of materials, dried at 60°C for 12 h to fully dry and remove moisture, and then added into a twin-screw extruder for melt blending to prepare a bio-based composite material. The temperatures of Zone I, Zone II, Zone III, Zone IV, Zone V, Zone VI and the die head of the extruder were 165°C, 175°C, 175°C, 175°C, 175°C, 160°C, respectively. The screw speed was 70 r / min and the feeding rate was 8.0 r / min.

[0027] (2) The blend sample was preheated at 175°C using a flat plate vulcanizer. After the blend melted, it was hot pressed for 6 minutes. After that, it was cold pressed for 6 minutes in another instrument to obtain a blend film. FTIR analysis was then performed. The test range was 4000-600 cm -1 , with a resolution of 0.5cm -1 , wave number accuracy is 0.01cm -1 , the scanning frequency is 75 times / second.

[0028] (3) Weigh approximately 15 mg of the purified and dried PLA / PBS blend and a 3% ESA PLA / PBS / ESA blend. Analyze and test using a nuclear magnetic resonance spectrometer with 128 scans using deuterated chloroform and tetramethylsilane (TMS) as the solvent and internal standard, respectively.

[0029] (4) Prepare a certain mass of dry sample and weigh it. Record the initial mass of the sample and place the sample in the ethanol solvent to ensure that the sample is completely immersed. Let the sample soak in the solvent (ethanol) for 72 hours to achieve swelling equilibrium. Then, after a predetermined time, remove the sample and remove excess liquid. Use filter paper to gently remove excess liquid on the surface. Record the wet mass of the sample after soaking and calculate the swelling rate of the sample ( S r ).

[0030] (5) The thermal properties of the blends were studied using a differential scanning calorimeter under a nitrogen atmosphere. About 5-8 mg of sample was placed in a crucible for sample preparation. After sample preparation, the crucible was placed in the instrument and the temperature was increased from 25°C to 200°C at a rate of 10°C / min. The temperature was then maintained constant for 5 minutes. The temperature was then lowered to 0°C at the same rate of 10°C / min, maintained constant for another 5 minutes, and finally increased to 200°C at the same rate of 10°C / min.

[0031] (6) The prepared samples were molded into standard specimens for tensile and impact tests in a WZS10D micro-injection molding machine at a barrel temperature of 175°C, a mold temperature of 40°C, and a holding time of 10 seconds. The excess parts were trimmed. Subsequently, the specimens were subjected to a tensile test at a rate of 20 mm / min in accordance with GB / T 1040.2-2022 / 1BA to determine their tensile strength and elongation at break. At the same time, the specimens were subjected to an impact test using a 150° pendulum initial angle and an initial potential energy of 2.750 J in accordance with GB / T 1843-2008 / A to determine their impact strength.

[0032] (7) The prepared composite material particles were pressed into a film about 80 μm thick using a flat vulcanizer at a pressure of 10 MPa, and then the transmittance was tested using a haze meter.

[0033] (8) The contact angle of the blend was measured using an angular contact meter. A 1 μL sessile water droplet was deposited on the surface of the prepared sample by a syringe pump, and the contact angle value was extracted from the recorded droplet image using software based on an ellipse model. To obtain the average value, five droplets were deposited at different locations on the sample. The surface of the test sample was evaluated by measuring the contact angles of distilled water and diiodomethane. The adhesion work (W) of the sample was evaluated based on the contact angle value.α ) and surface energy (γ). Example 2

[0034] 80 parts of polylactic acid; 20 parts of polybutylene succinate; 2 parts of epoxy-functionalized styrene-acrylic acid copolymer; 0.1 part antioxidant.

[0035] (1) PLA and PBS were placed in a vacuum drying oven according to the number of materials, dried at 60°C for 12 h to fully dry and remove moisture, and then added into a twin-screw extruder for melt blending to prepare a bio-based composite material. The temperatures of Zone I, Zone II, Zone III, Zone IV, Zone V, Zone VI and the die head of the extruder were 165°C, 175°C, 175°C, 175°C, 175°C, 160°C, respectively. The screw speed was 70 r / min and the feeding rate was 8.0 r / min.

[0036] (2) The blend sample was preheated at 175°C using a flat plate vulcanizer. After the blend melted, it was hot pressed for 6 minutes. After that, it was cold pressed for 6 minutes in another instrument to obtain a blend film. FTIR analysis was then performed. The test range was 4000-600 cm -1 , with a resolution of 0.5cm -1 , wave number accuracy is 0.01cm -1 , the scanning frequency is 75 times / second.

[0037] (3) Weigh approximately 15 mg of the purified and dried PLA / PBS blend and a 3% ESA PLA / PBS / ESA blend. Analyze and test using a nuclear magnetic resonance spectrometer with 128 scans using deuterated chloroform and tetramethylsilane (TMS) as the solvent and internal standard, respectively.

[0038] (4) Prepare a certain mass of dry sample and weigh it. Record the initial mass of the sample and place the sample in the ethanol solvent to ensure that the sample is completely immersed. Let the sample soak in the solvent (ethanol) for 72 hours to achieve swelling equilibrium. Then, after a predetermined time, remove the sample and remove excess liquid. Use filter paper to gently remove excess liquid on the surface. Record the wet mass of the sample after soaking and calculate the swelling rate of the sample ( S r ).

[0039] (5) The thermal properties of the blends were studied using a differential scanning calorimeter under a nitrogen atmosphere. About 5-8 mg of sample was placed in a crucible for sample preparation. After sample preparation, the crucible was placed in the instrument and the temperature was increased from 25°C to 200°C at a rate of 10°C / min. The temperature was then maintained constant for 5 minutes. The temperature was then lowered to 0°C at the same rate of 10°C / min, maintained constant for another 5 minutes, and finally increased to 200°C at the same rate of 10°C / min.

[0040] (6) The prepared samples were molded into standard specimens for tensile and impact tests in a WZS10D micro-injection molding machine at a barrel temperature of 175°C, a mold temperature of 40°C, and a holding time of 10 seconds. The excess parts were trimmed. Subsequently, the specimens were subjected to a tensile test at a rate of 20 mm / min in accordance with GB / T 1040.2-2022 / 1BA to determine their tensile strength and elongation at break. At the same time, the specimens were subjected to an impact test using a 150° pendulum initial angle and an initial potential energy of 2.750 J in accordance with GB / T 1843-2008 / A to determine their impact strength.

[0041] (7) The prepared composite material particles were pressed into a film about 80 μm thick using a flat vulcanizer at a pressure of 10 MPa, and then the transmittance was tested using a haze meter.

[0042] (8) The contact angle of the blend was measured using an angular contact meter. A 1 μL sessile water droplet was deposited on the surface of the prepared sample by a syringe pump, and the contact angle value was extracted from the recorded droplet image using software based on an ellipse model. To obtain the average value, five droplets were deposited at different locations on the sample. The surface of the test sample was evaluated by measuring the contact angles of distilled water and diiodomethane. The adhesion work (W) of the sample was evaluated based on the contact angle value. α ) and surface energy (γ). Example 3

[0043] 80 parts of polylactic acid; 20 parts of polybutylene succinate; 3 parts of epoxy-functionalized styrene-acrylic acid copolymer; 0.1 part antioxidant.

[0044] (1) PLA and PBS were placed in a vacuum drying oven according to the number of materials, dried at 60°C for 12 h to fully dry and remove moisture, and then added into a twin-screw extruder for melt blending to prepare a bio-based composite material. The temperatures of Zone I, Zone II, Zone III, Zone IV, Zone V, Zone VI and the die head of the extruder were 165°C, 175°C, 175°C, 175°C, 175°C, 160°C, respectively. The screw speed was 70 r / min and the feeding rate was 8.0 r / min.

[0045] (2) The blend sample was preheated at 175°C using a flat plate vulcanizer. After the blend melted, it was hot pressed for 6 minutes. After that, it was cold pressed for 6 minutes in another instrument to obtain a blend film. FTIR analysis was then performed. The test range was 4000-600 cm -1 , with a resolution of 0.5cm -1 , wave number accuracy is 0.01cm -1 , the scanning frequency is 75 times / second.

[0046] (3) Weigh approximately 15 mg of the purified and dried PLA / PBS blend and a 3% ESA PLA / PBS / ESA blend. Analyze and test using a nuclear magnetic resonance spectrometer with 128 scans using deuterated chloroform and tetramethylsilane (TMS) as the solvent and internal standard, respectively.

[0047] (4) Prepare a certain mass of dry sample and weigh it. Record the initial mass of the sample and place the sample in the ethanol solvent to ensure that the sample is completely immersed. Let the sample soak in the solvent (ethanol) for 72 hours to achieve swelling equilibrium. Then, after a predetermined time, remove the sample and remove excess liquid. Use filter paper to gently remove excess liquid on the surface. Record the wet mass of the sample after soaking and calculate the swelling rate of the sample ( S r ).

[0048] (5) The thermal properties of the blends were studied using a differential scanning calorimeter under a nitrogen atmosphere. About 5-8 mg of sample was placed in a crucible for sample preparation. After sample preparation, the crucible was placed in the instrument and the temperature was increased from 25°C to 200°C at a rate of 10°C / min. The temperature was then maintained constant for 5 minutes. The temperature was then lowered to 0°C at the same rate of 10°C / min, maintained constant for another 5 minutes, and finally increased to 200°C at the same rate of 10°C / min.

[0049] (6) The prepared samples were molded into standard specimens for tensile and impact tests in a WZS10D micro-injection molding machine at a barrel temperature of 175°C, a mold temperature of 40°C, and a holding time of 10 seconds. The excess parts were trimmed. Subsequently, the specimens were subjected to a tensile test at a rate of 20 mm / min in accordance with GB / T 1040.2-2022 / 1BA to determine their tensile strength and elongation at break. At the same time, the specimens were subjected to an impact test using a 150° pendulum initial angle and an initial potential energy of 2.750 J in accordance with GB / T 1843-2008 / A to determine their impact strength.

[0050] (7) The prepared composite material particles were pressed into a film about 80 μm thick using a flat vulcanizer at a pressure of 10 MPa, and then the transmittance was tested using a haze meter.

[0051] (8) The contact angle of the blend was measured using an angular contact meter. A 1 μL sessile water droplet was deposited on the surface of the prepared sample by a syringe pump, and the contact angle value was extracted from the recorded droplet image using software based on an ellipse model. To obtain the average value, five droplets were deposited at different locations on the sample. The surface of the test sample was evaluated by measuring the contact angles of distilled water and diiodomethane. The adhesion work (W) of the sample was evaluated based on the contact angle value. α ) and surface energy (γ). Example 4

[0052] 80 parts of polylactic acid; 20 parts of polybutylene succinate; 4 parts of epoxy-functionalized styrene-acrylic acid copolymer; 0.1 part antioxidant.

[0053] (1) PLA and PBS were placed in a vacuum drying oven according to the number of materials, dried at 60°C for 12 h to fully dry and remove moisture, and then added into a twin-screw extruder for melt blending to prepare a bio-based composite material. The temperatures of Zone I, Zone II, Zone III, Zone IV, Zone V, Zone VI and the die head of the extruder were 165°C, 175°C, 175°C, 175°C, 175°C, 160°C, respectively. The screw speed was 70 r / min and the feeding rate was 8.0 r / min.

[0054] (2) The blend sample was preheated at 175°C using a flat plate vulcanizer. After the blend melted, it was hot pressed for 6 minutes. After that, it was cold pressed for 6 minutes in another instrument to obtain a blend film. FTIR analysis was then performed. The test range was 4000-600 cm -1 , with a resolution of 0.5cm -1 , wave number accuracy is 0.01cm -1 , the scanning frequency is 75 times / second.

[0055] (3) Weigh approximately 15 mg of the purified and dried PLA / PBS blend and a 3% ESA PLA / PBS / ESA blend. Analyze and test using a nuclear magnetic resonance spectrometer with 128 scans using deuterated chloroform and tetramethylsilane (TMS) as the solvent and internal standard, respectively.

[0056] (4) Prepare a certain mass of dry sample and weigh it. Record the initial mass of the sample and place the sample in the ethanol solvent to ensure that the sample is completely immersed. Let the sample soak in the solvent (ethanol) for 72 hours to achieve swelling equilibrium. Then, after a predetermined time, remove the sample and remove excess liquid. Use filter paper to gently remove excess liquid on the surface. Record the wet mass of the sample after soaking and calculate the swelling rate of the sample ( S r ).

[0057] (5) The thermal properties of the blends were studied using a differential scanning calorimeter under a nitrogen atmosphere. About 5-8 mg of sample was placed in a crucible for sample preparation. After sample preparation, the crucible was placed in the instrument and the temperature was increased from 25°C to 200°C at a rate of 10°C / min. The temperature was then maintained constant for 5 minutes. The temperature was then lowered to 0°C at the same rate of 10°C / min, maintained constant for another 5 minutes, and finally increased to 200°C at the same rate of 10°C / min.

[0058] (6) The prepared samples were molded into standard specimens for tensile and impact tests in a WZS10D micro-injection molding machine at a barrel temperature of 175°C, a mold temperature of 40°C, and a holding time of 10 seconds. The excess parts were trimmed. Subsequently, the specimens were subjected to a tensile test at a rate of 20 mm / min in accordance with GB / T 1040.2-2022 / 1BA to determine their tensile strength and elongation at break. At the same time, the specimens were subjected to an impact test using a 150° pendulum initial angle and an initial potential energy of 2.750 J in accordance with GB / T 1843-2008 / A to determine their impact strength.

[0059] (7) The prepared composite material particles were pressed into a film about 80 μm thick using a flat vulcanizer at a pressure of 10 MPa, and then the transmittance was tested using a haze meter.

[0060] (8) The contact angle of the blend was measured using an angular contact meter. A 1 μL sessile water droplet was deposited on the surface of the prepared sample by a syringe pump, and the contact angle value was extracted from the recorded droplet image using software based on an ellipse model. To obtain the average value, five droplets were deposited at different locations on the sample. The surface of the test sample was evaluated by measuring the contact angles of distilled water and diiodomethane. The adhesion work (W) of the sample was evaluated based on the contact angle value. α ) and surface energy (γ).

[0061] The composite material samples prepared in the comparative example and the embodiment were respectively subjected to infrared spectral analysis.

[0062] Experiments show that the spectral characteristics of the PLA / PBS binary system and the PLA / PBS / ESA ternary system are highly similar, but the ternary system exhibits new characteristic absorption peaks at 700 cm⁻¹ and 1728 cm⁻¹. Comparative analysis indicates that these peaks correspond to the out-of-plane bending vibration of the monosubstituted hydrogen atom in the benzene ring (700 cm⁻¹) and the stretching vibration of the carbonyl group (C=O) (1728 cm⁻¹) in the ESA molecule, respectively. Notably, the ternary blend lacks the characteristic absorption peaks of the epoxy functional group of ESA at 908 cm⁻¹ and 845 cm⁻¹. Analysis suggests that the mechanism of this phenomenon can be summarized as follows: During melt blending, the epoxy groups of ESA preferentially undergo a ring-opening reaction with the carboxyl groups at the end of the PBS molecular chain. Due to the hydroxyl-terminated PLA molecules and the combined presence of both carboxyl and hydroxyl groups in PBS, the ESA and PBS molecules form a three-dimensional cross-linked network. At the same time, ESA acts as an interfacial compatibilizer, and its active groups can undergo esterification condensation reactions with the hydroxyl groups of PLA and the carboxyl groups of PBS, respectively, to form a block copolymer with a PLA-b-ESA-b-PBS structure. This chemical bonding not only enhances the interfacial bonding strength between PLA and PBS, but also completely consumes the epoxy functional groups of ESA, causing the original characteristic absorption peaks (908cm⁻¹ and 845cm⁻¹) to disappear in the ternary system.

[0063] The composite material samples were tested by hydrogen nuclear magnetic resonance spectroscopy.

[0064] like Figure 2 NMR spectra show that both samples exhibit a typical resonance peak for methyl protons in the PLA chain at 1.7 ppm, while a characteristic signal for methylene protons in the PBS component is detected at 5.2 ppm. Amplification and analysis of the peaks in the characteristic ranges of (1.4-1.8) ppm and (6.0-8.0) ppm reveal that a characteristic peak of aromatic protons attributable to the benzene ring structure of the ESA molecule can be clearly identified in the 6.5-7.3 ppm range after the introduction of the compatibilizer system. These spectral analysis results indicate that the epoxy functional groups of the ESA in the modified system undergo a characteristic ring-opening reaction with the carboxyl and hydroxyl groups at the ends of the PLA / PBS chains, forming a stable interfacial chemical connection through covalent bonding. This reaction mechanism effectively explains the interfacial compatibilization effect of ESA in the PLA / PBS blend.

[0065] The swelling rate of the composite material samples prepared in the comparative example and the embodiment was tested respectively.

[0066] Table 1 Swelling ratio of composite materials sample Swelling rate (%) Comparative Example 1 4.86 Example 1 6.29 Example 2 7.16 Example 3 8.01 Example 4 9.10 Experiments have shown that adding the hydrophobic agent ESA to the blend significantly increases the swelling rate. In Example 4, the swelling rate rose to 9.1%, a significant improvement compared to when the blend was not added. This mechanism is due to the reaction between the hydroxyl or carboxyl groups at the ends of the PLA / PBS molecular chains and the epoxy groups of the ESA, forming a three-dimensional cross-linked network. This structure has a stronger liquid-carrying capacity than the original linear molecules, and as the ESA content increases, the density and volume of the cross-linked network increase simultaneously, thereby continuously enhancing the swelling performance.

[0067] Comprehensive sample infrared spectral feature analysis, nuclear magnetic resonance hydrogen spectrum test and swelling rate test showed that the introduction of ESA successfully improved the interfacial compatibility between PLA / PBS molecules.

[0068] The composite material samples prepared in the comparative example and the embodiment were subjected to DSC tests respectively.

[0069] Table 2 DSC test results of blends sample <![CDATA[T g (PLA) / ℃]]> <![CDATA[T m (PBS) / ℃]]> <![CDATA[T m (PLA) / ℃]]> <![CDATA[ΔH m (PLA)J / g]]> <![CDATA[X c (PLA) / %]]> Comparative Example 1 57.61 113.35 149.85 18.51 19.77 Example 1 57.44 113.25 149.75 13.25 14.15 Example 2 57.77 113.19 148.78 11.18 11.94 Example 3 57.82 112.90 148.75 10.88 11.62 Example 4 57.46 112.71 148.38 10.84 11.58 Figure 1 The DSC heating curve shows that the blend material has a glass transition temperature (T g ), 113℃ is the PBS melting peak, 120-130℃ exothermic peak is due to PLA cold crystallization, and 149℃ corresponds to PLA melting peak. The data in Table 1 show that the addition of ESA does not significantly change the T of PLA. g However, as the ESA content increased (to 4 wt%), the melting temperatures of PLA and PBS decreased from 149.85°C (a decrease of 1.47°C) to 148.38°C (a decrease of 1.47°C) and 113.35°C (a decrease of 0.64°C), respectively. Simultaneously, the PLA crystallinity decreased from 19.77% to 11.58%. This is attributed to the fact that ESA enhanced the interfacial adhesion between the two phases, improved the system compatibility, and disrupted the molecular chain regularity, resulting in the incorporation of more PBS into the PLA phase and inhibiting its crystallization ability.

[0070] The mechanical properties of the composite materials samples prepared in the comparative example and the embodiment were tested respectively.

[0071] Table 3 Mechanical properties test results of composite materials sample <![CDATA[Izod impact strength (J / m 2 )]]> Elongation at break (%) Comparative Example 1 2816.0 102.32 Example 1 3326.3 195.22 Example 2 4409.5 232.19 Example 3 5178.1 247.93 Example 4 3672.4 207.78 The data in Table 3 show that after the introduction of ESA in Example 3, the composite material's notched impact strength reached an optimal value of 5178.1 J / m², a 184% increase compared to Comparative Example 1. Simultaneously, the elongation at break also significantly increased to 247.93%, a 242% increase compared to Comparative Example 1. This demonstrates that the addition of ESA significantly improves the composite material's notched impact strength and elongation at break, effectively balancing the material's toughness and rigidity.

[0072] The composite material samples prepared in the comparative example and the embodiment were tested for transmittance and haze.

[0073] Table 4 Transmittance and haze of composite materials sample Transmittance (%) Haze (%) Comparative Example 1 88.3 65.8 Example 1 88.3 63.7 Example 2 88.6 53.1 Example 3 89.0 46.1 Example 4 88.8 37.5 According to the data in Table 4, the addition of ESA significantly reduced the material's haze, from 65.8% in Comparative Example 1 to a minimum of 37.5%, while maintaining the transmittance of the PLA / PBS composite at approximately 88.5%. This ensures excellent optical properties. This demonstrates that ESA can improve the material's optical transparency, facilitating practical applications.

[0074] The contact angle tests were performed on the composite material samples prepared in the comparative example and the embodiment.

[0075] Table 5 Contact angles of composite materials

[0076] According to the data in Table 5, the addition of the hydrophobic polymer ESA significantly improves the hydrophobic properties of the PLA / PBS blend. In Example 3, the water contact angle of the material increased from 47.64° to 77.32°, a 62% increase, and the hydrophobic effect continued to increase with the amount of ESA used. This is due to the accumulation of ESA's hydrophobic groups on the material surface, forming a hydrophobic layer. Simultaneously, the addition of ESA reduces the material's surface energy, dropping to 30.23 mN / m at a 4% dosage. Surface energy is composed of a dispersive component (non-polar forces) and a polar component, with the dispersive component predominating and reflecting the material's surface morphology. This confirms the key role of reactive compatibilizers in regulating the hydrophobic properties of biodegradable materials.

[0077] The description of the above embodiments is only intended to help understand the method of the present invention and its core concept. It should be noted that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications may be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The above embodiments are only intended to facilitate a clear explanation of the method of the present invention and its core concept. Professionals should understand that technical improvements and changes may be made to the present invention without departing from the principles and spirit disclosed by the present invention. These corresponding improvements and changes should also be regarded as the scope of protection covered by the claims of the present invention.

Claims

1. A multi-effect modified biodegradable composite material, characterized in that: The modified PLA-based composite material comprises the following raw materials: 30-90 parts of polylactic acid; 10-70 parts of polybutylene succinate; 1-10 parts of environmentally friendly additives; 0.1-0.5 parts of antioxidant.

2. The multi-effect modified biodegradable composite material according to claim 1, characterized in that: The environmentally friendly auxiliary agent is one or more of styrene-glycidyl methacrylate (ADR), polyhydroxyalkanoate (PHA), end-epoxy branched polymer (ETBP), and epoxy-functionalized styrene-acrylic acid copolymer (ESA).

3. The multi-effect modified biodegradable composite material according to claim 1, characterized in that: The antioxidant is one or more of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and 2,6-di-tert-butyl-4-methylphenol.

4. A method for preparing a multi-effect modified biodegradable composite material, characterized in that: The preparation method includes the following preparation process: PLA and PBS were placed in a vacuum drying oven and dried at 60°C for 12 h to remove moisture. They were then added to a twin-screw extruder for melt blending to prepare bio-based composite materials. The temperatures of zones I, II, III, IV, V, VI and the die head of the extruder were 165°C, 175°C, 175°C, 175°C, 175°C, 175°C and 160°C, respectively. The screw speed was 70 r / min and the feeding rate was 8.0 r / min.

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