Bio-based material capable of being biologically degraded in whole domain and high in heat resistance as well as preparation method and application of bio-based material

Abstract

The invention belongs to the technical field of degradable materials, and provides a high-heat-resistance bio-based material capable of being biologically degraded in a global manner as well as a preparation method and application of the high-heat-resistance bio-based material. The polyhydroxyalkanoate, the plant filler and the nano-cellulose in a specific ratio are used as main raw material components, the polyhydroxyalkanoate is poly-3-hydroxybutyric acid and poly-3-hydroxybutyric acid copolymerized 4-hydroxybutyrate, the plant filler is granular and can be degraded in the natural environment, the bio-based carbon content is larger than 95%, and the environment-friendly effect is achieved; the material has excellent heat resistance, has a heat distortion temperature (HDT) of more than or equal to 100 DEG C, can be used in a hot solvent, can keep natural plant pigments and colors, has good thermoplasticity and processability, is suitable for extrusion and injection molding, and can be used for preparing disposable plastic products.

Description

Technical Field

[0001] This invention relates to the field of biodegradable materials technology, and more specifically, to a bio-based material that is biodegradable in all regions and highly heat-resistant, as well as its preparation method and application. Background Technology

[0002] Traditional plastic straws are mainly made of petroleum-based plastics (polyethylene PE or polypropylene PP), which are non-degradable and can easily cause microplastic pollution in the ocean and soil. In addition, they have insufficient heat resistance, are prone to deformation at high temperatures and release plasticizers, which limits their application in high-temperature environments.

[0003] Currently, some biodegradable straws have emerged, but all have limitations. For example, while polylactic acid (PLA) is biodegradable, its primary degradation method currently relies on industrial composting conditions at 58±2℃ (ASTM D6400, Specification for Compostable Plastics), and it cannot degrade in natural environments (such as seawater or soil). Its heat distortion temperature is <55℃, requiring secondary crystallization to raise the heat distortion temperature to above 100℃. Similarly, while polybutylene succinate (PBS) is also biodegradable, it can only be degraded through home or industrial composting, not in natural environments (such as seawater or soil). Furthermore, its bio-based carbon content is <50%, it relies on petrochemical monomer raw materials, and its heat distortion temperature is <90℃. Although polyhydroxy fatty acids (PHA) can degrade in natural environments, such as seawater (complying to ISO 18830:2016 Plastics. Determination of aerobic biodegradation of non-floating plastic materials at seawater / sand sediment interface. Method for measuring oxygen demand in a closed breathalyzer), their raw materials are usually grain fermentation products, which are too expensive. They also have low melt strength (melt flow index > 30 g / 10 min), are prone to flash during injection molding or extrusion, are difficult to process, and have poor toughness.

[0004] Therefore, there is an urgent need to develop a biodegradable plastic that can degrade in natural environments, such as seawater or soil, without relying on petroleum-based plastic raw materials, and can reach a high heat distortion temperature (greater than 100°C) without secondary crystallization, meeting the needs of high-temperature applications, and can be further used to prepare biodegradable straws, etc. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a fully biodegradable, highly heat-resistant bio-based material, its preparation method, and its applications. The bio-based material provided by this invention is fully biodegradable, such as being able to degrade directly in seawater, soil, and compost, has a high bio-based carbon content (all reaching over 95%), does not rely on petroleum-based plastic raw materials, and has a heat distortion temperature greater than 100℃, exhibiting excellent heat resistance and requiring no secondary crystallization.

[0006] The first aspect of the present invention provides a bio-based material that is fully biodegradable and highly heat-resistant.

[0007] Specifically, a bio-based material that is fully biodegradable and highly heat-resistant comprises the following raw material components by weight: 50-80 parts of polyhydroxyalkanoate (PHA) 6-40 parts of plant filler 3-14 parts of nanocellulose; The polyhydroxy fatty acid ester is poly(3-hydroxybutyric acid) (PHB) and poly(3-hydroxybutyric acid) copoly(4-hydroxybutyrate) (P34HB). The plant filler is in granular form.

[0008] This invention uses PHA as the continuous phase substrate, with high-melting-point PHB (Tm≈175℃) as the substrate framework and low-melting-point P34HB (Tm≈160℃) as the viscous flow phase to improve the material's heat resistance, achieving a heat distortion temperature greater than 100℃. The combination of PHB and P34HB leverages the high crystallinity, high rigidity, and high strength of PHB, while also incorporating the low crystallinity and high toughness of P34HB, thus balancing the overall performance of the material and achieving a balance between rigidity and toughness, as well as between high strength and high ductility. In addition, this invention uses a combination of plant fillers and nanocellulose. The plant fillers are granular, while the nanocellulose is fibrous. The plant fillers can promote the overall natural degradation rate of the material, while the nanocellulose plays the role of supporting skeleton in the composite material. When present in a specific amount, the plant fillers and nanocellulose form an "interlocking structure", which not only makes the supporting skeleton more stable and significantly improves the rigidity of the material, but also can conduct and disperse external impact forces over a wider range, significantly improving the impact resistance of the material. Moreover, as a supporting skeleton, nanocellulose can improve the material's resistance to heat deformation and improve the material's heat resistance.

[0009] More preferably, the bio-based material comprises, by weight, the following raw material components: Polyhydroxyalkanoate (PHA) 60-80 parts Plant-based filler 8-35 parts 3-12 parts of nanocellulose.

[0010] Preferably, the mass ratio of the poly(3-hydroxybutyric acid) and the poly(3-hydroxybutyric acid) copolymer 4-hydroxybutyrate is 1:1 to 1:4.

[0011] More preferably, the mass ratio of the poly(3-hydroxybutyric acid) and the poly(3-hydroxybutyric acid) copolymer 4-hydroxybutyrate is 1:1.2-1:3.6.

[0012] Preferably, the poly(3-hydroxybutyric acid) (PHB) has a weight-average molecular weight of 600,000 to 1,000,000.

[0013] More preferably, the poly(3-hydroxybutyric acid) (PHB) has a weight-average molecular weight of 700,000 to 800,000.

[0014] Preferably, the weight-average molecular weight of the poly(3-hydroxybutyric acid) copolymer 4-hydroxybutyrate (P34HB) is 400,000 to 800,000.

[0015] More preferably, the weight-average molecular weight of the poly(3-hydroxybutyric acid) copolymer 4-hydroxybutyrate (P34HB) is 600,000 to 700,000.

[0016] Preferably, the molar mass of 4-hydroxybutyric acid (4HB) in the poly(3-hydroxybutyric acid) copolymer 4-hydroxybutyrate (P34HB) is 2%-15%.

[0017] More preferably, the molar mass of 4-hydroxybutyric acid (4HB) in the poly(3-hydroxybutyric acid) copolymer 4-hydroxybutyrate (P34HB) is 6%-12%.

[0018] Preferably, the average particle size of the plant filler is 20 to 200 mesh. Since the plant filler used in this invention is granular, it can be obtained through simple crushing without the need for mechanical grinding. Therefore, it avoids fiber charring, deterioration, and loss of natural pigments caused by the high temperatures (>80°C) generated by mechanical grinding, and also saves time and costs. Furthermore, the material ultimately produced by this invention has a rough surface, three-dimensional plant particles, a strong sensory appeal, a texture close to natural wood, and the color of natural plants, avoiding a plastic feel and possessing a natural appearance.

[0019] Preferably, the average fiber length of the nanocellulose is ≤1000μm, and / or the average fiber diameter of the nanocellulose is ≤60μm.

[0020] More preferably, the average fiber length of the nanocellulose is ≤800μm, and / or the average fiber diameter of the nanocellulose is ≤50μm.

[0021] Preferably, the cellulose content in the nanocellulose is ≥99% by mass.

[0022] More preferably, the cellulose content in the nanocellulose is ≥99.5%.

[0023] Preferably, the weight ratio of the plant filler to nanocellulose is 1:1 to 2:1.

[0024] Preferably, the moisture content of the plant filler is ≤1% by mass. Since the mixture is processed by melt processing at a temperature of about 150-180°C, controlling the moisture content at this temperature helps to avoid the hydrolysis of ester bonds in PHA, which would lead to a decrease in molecular weight, and also helps to avoid water vaporization, which would form micropores and cause a decrease in material density.

[0025] Preferably, the plant filler is at least one of pandan powder, wood powder, bamboo powder, bagasse powder, coffee grounds powder, tea grounds powder, alfalfa powder, peanut shell powder, and walnut shell powder. The plant filler can be derived from plant stems, stalks, bark, leaves, fruit peels, shells, etc. Agricultural waste can be used as the plant filler to improve its utilization rate. Using agricultural waste (such as pandan and coffee grounds) as raw materials realizes the "waste-product-fertilizer" link, which conforms to sustainable development. The product can also enhance fertility, which is beneficial to the growth of animals and plants. Moreover, it eliminates the need to use grain or its fermentation products, reducing costs and saving grain.

[0026] Preferably, the plant filler is a plant filler pretreated with a coupling agent.

[0027] Preferably, the coupling agent is at least one selected from aluminate coupling agents, titanate coupling agents, and vinylsiloxane coupling agents. By high-temperature blending the coupling agent with nanocellulose, the coupling agent coats the surface of the nanocellulose. Because one end of the coupling agent contains an inorganic-philic group and the other end contains an organic-philic group, the inorganic-philic group forms strong hydrogen bonds with the hydroxyl groups of the nanocellulose, and the organic-philic group forms van der Waals forces with the PHA substrate, acting as a molecular bridge and enhancing the interfacial compatibility of the components.

[0028] Preferably, the raw material components of the bio-based material also include additives.

[0029] Preferably, the adjuvant includes at least one of a nucleating agent and / or an antioxidant.

[0030] More preferably, the adjuvant includes a nucleating agent and an antioxidant.

[0031] More preferably, the bio-based material comprises, by weight, the following additives: 0.1-2 parts of nucleating agent and 0.1-2 parts of antioxidant.

[0032] More preferably, the bio-based material comprises, by weight, the following additives: 0.4-1.5 parts of nucleating agent and 0.4-1 parts of antioxidant.

[0033] Preferably, the nucleating agent is at least one of talc, boron nitride, titanium nitride, acylhydrazine nucleating agents (such as diphenyl dihydrazine sebacate), and sorbitol.

[0034] Preferably, the antioxidant is a hindered phenolic antioxidant and / or a phosphite antioxidant.

[0035] More preferably, the antioxidant is a compound of hindered phenolic antioxidants (such as antioxidant 1010) and phosphite antioxidants (such as antioxidant 168).

[0036] More preferably, the antioxidant is a compound of hindered phenolic antioxidants and phosphite antioxidants in a weight ratio of 1-2:1-2.

[0037] A second aspect of the present invention provides a method for preparing a bio-based material that is biodegradable throughout the entire range and highly heat-resistant.

[0038] A method for preparing a bio-based material that is fully biodegradable and highly heat-resistant includes the following steps: The raw material components are mixed, melt-blended and granulated, and then post-processed to obtain the bio-based material.

[0039] Preferably, the melt blending granulation is carried out in a parallel twin-screw extruder, with the polyhydroxyalkanoate, plant filler, and nanocellulose fed separately from different feed ports of the extruder. This invention, by feeding the polyhydroxyalkanoate, plant filler, and nanocellulose separately, helps to prevent the plant filler and nanocellulose from being thermally oxidized and degraded.

[0040] More preferably, the melt blending granulation is carried out in a parallel twin-screw extruder (such as an AK73 type). The parallel twin-screw extruder includes a main feed port, a first side feed port, and a second side feed port. Polyhydroxyalkanoates (PHA) are fed through the main feed port, plant-based fillers are fed through the first side feed port, and nanocellulose is fed through the second side feed port. This invention employs a staged feeding method. PHA enters through the main feed port, is preheated, melted, and plasticized, plant-based fillers are added through the first side feed port for dispersion and mixing, and nanocellulose is added through the second side feed port to prevent damage to the fiber aspect ratio, thus ensuring better reinforcement and toughening effects.

[0041] Preferably, the raw material components further include an auxiliary agent, which is fed together with the polyhydroxyalkanoate through the same feed port.

[0042] Preferably, the length-to-diameter ratio of the parallel twin-screw extruder is 40-56:1.

[0043] Preferably, the parallel twin-screw extruder includes a main feed port, and the length-to-diameter ratio of the main feed port to the main feed port is 32-48:1; and / or, the length-to-diameter ratio of the second side feed port to the main feed port is 20-36:1.

[0044] Preferably, the barrel front section temperature of the parallel twin-screw extruder is 165-175℃, and / or the barrel middle section temperature is 155-165℃, and / or the barrel rear section temperature is 160-170℃, and / or the die temperature is 170-180℃, and / or the screw speed is 200-800 rpm, and / or the vacuum degree of the parallel twin-screw extruder is ≤1000Pa.

[0045] Preferably, the post-processing is drying.

[0046] Preferably, the drying temperature is 70-90°C, and / or the drying time is ≥4 hours. The drying temperature and time are controlled to ensure stability.

[0047] A third aspect of the present invention provides an application of a bio-based material that is fully biodegradable and highly heat-resistant.

[0048] Application of a biodegradable and heat-resistant bio-based material in the preparation of biodegradable tableware, biodegradable packaging materials, biodegradable decorative materials or biodegradable textiles.

[0049] Preferably, the biodegradable tableware includes straws, knives, forks, spoons, trays, lids, or lunch boxes.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses polyhydroxy fatty acid ester (PHA), plant filler, and nanocellulose in a specific ratio as the main raw material components. The polyhydroxy fatty acid ester is poly(3-hydroxybutyric acid) and poly(3-hydroxybutyric acid) copolymerized with 4-hydroxybutyrate, and the plant filler is in granular form. All of these are bio-based raw materials. The bio-based material provided by this invention possesses comprehensive biodegradability, including degradation in the ocean, home composting, freshwater, and soil (with a weight loss rate of >90% in seawater degradation over 6 months). The degradation products are CO2, H2O, and humus, resulting in no microplastic pollution and enhancing soil fertility. It does not use petroleum-based plastic raw materials, has a bio-based carbon content >95%, is environmentally friendly, and reduces costs (more than 40% lower than traditional pure PHA materials). Furthermore, it exhibits excellent heat resistance, with a heat distortion temperature (HDT) reaching 103-117℃, achieving high heat resistance without secondary heat treatment, making it suitable for high-temperature environments (such as hot water, hot drinks, and steam sterilization). This is superior to traditional biodegradable materials PLA (HDT < 55℃) and PBS (HDT < 90℃), broadening its applications. The bio-based material obtained by this invention also retains natural plant pigments, resulting in natural colors, aesthetic appeal, and is safe and non-toxic. In addition, bio-based materials have excellent mechanical properties, with tensile strength reaching 28-33 MPa, flexural modulus reaching 1782-1994 MPa, and cantilever beam notched impact strength reaching 3.8-4.5 MPa. They also have good thermoplasticity and processability, making them suitable for extrusion and injection molding. They can be used to prepare disposable plastic products, such as straws (which offer a better user experience than paper straws), knives, forks, spoons, trays, lids, and lunch boxes, and can be used both cold and hot. Attached Figure Description

[0051] Figure 1 This is an image of a straw obtained in Embodiment 1 of the present invention; Figure 2 This is an image of the straw obtained in Embodiment 2 of the present invention; Figure 3 This is an image of the straw obtained in Embodiment 3 of the present invention; Figure 4 This is an image of the straw obtained in Embodiment 4 of the present invention; Figure 5 This is a schematic diagram of the structure of the components after melt blending in step (2) of Embodiment 1 of the present invention. Detailed Implementation

[0052] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0053] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0054] The "bio-based carbon content" mentioned in this invention refers to the content of biodegradable organic carbon in biomass materials.

[0055] The "fully biodegradable" nature of this invention refers to complete degradation in natural environments (such as soil, seawater, compost, etc.), conforming to the standards for household composting degradation (AS 5810:2010 Biodegradable Plastics - Biodegradable Plastics Suitable for Household Composting), marine degradation (ASTM D6691-2022 Standard Test Method for Aerobic Biodegradability of Plastic Materials in Marine Environments), soil degradation (GB / T 22047-2008 Determination of Final Aerobic Biodegradability of Plastic Materials in Soil), and freshwater degradation (GBT19276.2-2003 Determination of Final Aerobic Biodegradability of Materials in Aqueous Culture Media by Determination of Released Carbon Dioxide). Within the time specified in the standards, the biodegradation rate is >90%, and the degradation products are CO2, H2O, and humus, with no microplastic pollution.

[0056] The main raw materials and equipment used in the embodiments and comparative examples of this invention are as follows: Polyhydroxybutyrate (PHB): weight average molecular weight of 800,000, product specification MDF1000, supplier is Zhuhai Maidefa Biomaterials Co., Ltd.

[0057] P34HB (6% 4HB): The 4HB comonomer has a molar content of 6%, a weight-average molecular weight of 700,000, and the product specification is MDF1500. The supplier is Zhuhai Maidefa Biomaterials Co., Ltd.

[0058] P34HB (12% 4HB): The 4HB comonomer has a molar content of 12%, a weight-average molecular weight of 600,000, and the product specification is MDF2000. The supplier is Zhuhai Maidefa Biomaterials Co., Ltd.

[0059] Plant-based fillers: sugarcane bagasse powder, pandan bagasse powder, coffee grounds powder, alfalfa powder, all of which are agricultural waste.

[0060] Nanocellulose: Cellulose content ≥99.5%, average fiber length ≤800μm, average fiber diameter ≤50μm, manufactured by Arbocel GmbH, Germany, model FIC 500 P.

[0061] Nucleating agent: diphenyl dihydrazide sebacate, supplied by Shanxi Chemical Research Institute, model TMC300.

[0062] Coupling agent: Titanate coupling agent.

[0063] Antioxidant: Antioxidant 1010 and antioxidant 168 are compounded in a weight ratio of 1:1 to form an antioxidant, supplied by BASF.

[0064] Polypropylene (PP): Produced by Sinopec Maoming Company, grade T30S.

[0065] Polylactic acid (PLA): Produced by Total Klein, grade LX175.

[0066] Polybutylene succinate (PBS): Produced by Zhuhai Kingfa Biomaterials Co., Ltd., brand name A200.

[0067] High-speed mixer: SHR-200A, Zhangjiagang Xinrong Machinery Co., Ltd.

[0068] Twin-screw extruder: AK73, 160KW, screw length-to-diameter ratio 52:1, Nanjing Keya Chemical Complete Equipment Co., Ltd.

[0069] Example 1 A bio-based material that is fully biodegradable and highly heat-resistant includes the raw material components shown in Table 1 below.

[0070] The preparation method of the above-mentioned biodegradable and highly heat-resistant bio-based material includes the following steps: (1) Surface activation pretreatment of coffee grounds Add 32 parts of coffee grounds to a high-speed mixer (the amount of grounds should be 30%-80% of the mixer's volume). First, mix at a low speed of 200 rpm. At the same time, add 2 parts of titanate coupling agent sequentially and evenly through the feed port. Then, increase the mixing speed to 1400 rpm for high-speed mixing and control the temperature of the mixing tank at 70±5℃. Mix for 15 minutes within this temperature range. After mixing, cool to obtain pretreated coffee grounds with a moisture content ≤1%.

[0071] (2) Melt blending granulation The melt blending and granulation were carried out using a parallel twin-screw extruder, as follows: 28 parts PHB, 33.6 parts P34HB (12% 4HB), 0.4 parts nucleating agent, and 1 part antioxidant were added to the main feed port; 34 parts pretreated coffee grounds were added to the first side feed port, with an aspect ratio of 32:1 from the first side feed port to the main discharge port; and 3 parts nanocellulose were added to the second side feed port, with an aspect ratio of 20:1 from the second side feed port to the main discharge port. The processing parameters are as follows: the temperatures of the front, middle and rear sections of the barrel are 168℃, 162℃ and 173℃ respectively; the die head temperature is 178℃; the rotation speed is 120rpm; and the vacuum degree is -0.08 to -0.1MPa.

[0072] like Figure 5 As shown, after melt blending, the PHA substrate (PHB and P34HB) serves as the continuous phase substrate. Pretreated coffee grounds (plant filler) and nanocellulose are uniformly dispersed in the continuous phase substrate and form an "interlocking structure". This not only makes the supporting skeleton more stable and significantly improves the stiffness of the material, but also enables it to conduct and disperse external impact forces over a wider range, significantly improving the impact resistance of the material.

[0073] (3) The granules obtained in step (2) are dehumidified and dried at 80°C for ≥4 hours until the moisture content of the granules is ≤400ppm. Then, they are vacuum sealed and packaged to obtain the finished product.

[0074] The material obtained in Example 1 was added to the hopper of a single-screw straw extruder. The extruder barrel conveying section temperature was 165°C, the melting and plasticizing section temperature was 175°C, the homogenization section temperature was 165°C, the die head temperature was 165°C, and the cooling water tank temperature was 45°C. Straw 1 was then processed.

[0075] Example 2 A bio-based material that is fully biodegradable and highly heat-resistant includes the raw material components shown in Table 1 below.

[0076] The preparation method of the above-mentioned biodegradable and highly heat-resistant bio-based material includes the following steps: (1) Surface activation pretreatment of sugarcane bagasse powder Sugarcane bagasse powder is added to a high-speed mixer at a rate of 30%-80% of the mixer's volume. The mixture is first stirred at a low speed of 200 rpm. While stirring at low speed, titanate coupling agent is added sequentially and uniformly through the feed hole. Then, the stirring speed is increased to 1400 rpm for high-speed stirring, and the temperature of the mixing tank is controlled at 70±5℃. The mixture is stirred for 15 minutes within this temperature range. After stirring, it is cooled to obtain pretreated sugarcane bagasse with a moisture content of ≤1%.

[0077] (2) Melt blending granulation The melt blending and granulation were carried out using a parallel twin-screw extruder, as follows: 15 parts of PHB, 54 parts of P34HB (12% 4HB), 0.6 parts of nucleating agent, and 0.8 parts of antioxidant were added to the main feed port; 24.6 parts of pretreated sugarcane bagasse were added to the first side feed port, with the length-to-diameter ratio from the first side feed port to the main discharge port being 32:1; and 5 parts of nanocellulose were added to the second side feed port, with the length-to-diameter ratio from the second side feed port to the main discharge port being 20:1.

[0078] The processing parameters are as follows: the temperatures of the front, middle and rear sections of the barrel are 175℃, 160℃ and 165℃ respectively; the die head is 175℃; the rotation speed is 140rpm; and the vacuum degree is -0.08 to -0.1MPa.

[0079] (3) The granules obtained in step (2) are subjected to dehumidification and drying treatment at 80°C for ≥4 hours until the moisture content of the granules is ≤400ppm. Then, they are vacuum sealed and packaged to obtain the finished product. Straw 2 is prepared using the same method as in Example 1.

[0080] Example 3 A bio-based material that is fully biodegradable and highly heat-resistant includes the raw material components shown in Table 1 below.

[0081] The preparation method of the above-mentioned biodegradable and highly heat-resistant bio-based material includes the following steps: (1) Surface activation pretreatment of alfalfa powder Add alfalfa powder to a high-speed mixer, with the amount of powder being 30%-80% of the mixer's volume. First, mix at a low speed of 200 r / min. While mixing at low speed, add titanate coupling agent sequentially and uniformly through the feed hole. Then, increase the mixing speed to 1400 r / min for high-speed mixing, and control the temperature of the mixing tank at 70±5℃. Mix within this temperature range for 15 minutes. After mixing is complete, cool to obtain pretreated alfalfa powder with a moisture content ≤1%.

[0082] (2) Melt blending granulation The melt blending and granulation were carried out using a parallel twin-screw extruder, as follows: 26 parts of PHB, 43 parts of P34HB (12% 4HB), 0.6 parts of nucleating agent, and 0.8 parts of antioxidant were added to the main feed port; 24.6 parts of pretreated alfalfa powder were added to the first side feed port, with the length-to-diameter ratio from the first side feed port to the main discharge port being 32:1; and 5 parts of nanocellulose were added to the second side feed port, with the length-to-diameter ratio from the second side feed port to the main discharge port being 20:1.

[0083] The processing parameters are as follows: the temperatures of the front, middle, and rear sections of the barrel are 170℃, 158℃, and 168℃, respectively; the die head temperature is 172℃; the screw speed is 160 rpm; and the vacuum degree is -0.08 to -0.1 MPa.

[0084] (3) The granules obtained in step (2) are subjected to dehumidification and drying treatment at 80°C for ≥4 hours until the moisture content of the granules is ≤400ppm. Then, they are vacuum sealed and packaged to obtain the finished product. Straw 3 is prepared using the same method as in Example 1.

[0085] Example 4 A bio-based material that is fully biodegradable and highly heat-resistant includes the raw material components shown in Table 1 below.

[0086] The preparation method of the above-mentioned biodegradable and highly heat-resistant bio-based material includes the following steps: (1) Surface activation pretreatment of pandan residue powder Add pandan residue powder to a high-speed mixer at a rate of 30%-80% of the mixer's volume. First, stir at a low speed of 200 r / min. While stirring at low speed, add titanate coupling agent sequentially and uniformly through the feed hole. Then, increase the stirring speed to 1400 r / min for high-speed stirring and control the temperature of the mixing tank at 70±5℃. Stir for 15 minutes within this temperature range. After stirring, cool to obtain pretreated pandan residue with a moisture content ≤1%.

[0087] (2) Melt blending granulation The melt blending and granulation were carried out using a parallel twin-screw extruder, as follows: 24 parts of PHB, 49.6 parts of P34HB (12% 4HB), 1.2 parts of nucleating agent, and 0.4 parts of antioxidant were added to the main feed port; 12.8 parts of pretreated pandan residue were added to the first side feed port, with the length-to-diameter ratio from the first side feed port to the main discharge port being 32:1; and 12 parts of nanocellulose were added to the second side feed port, with the length-to-diameter ratio from the second side feed port to the main discharge port being 20:1.

[0088] The processing parameters are as follows: the temperatures of the front, middle, and rear sections of the barrel are 167℃, 160℃, and 165℃, respectively; the die head temperature is 170℃; the screw speed is 180 rpm; and the vacuum degree is -0.08 to -0.1 MPa.

[0089] (3) The granules obtained in step (2) are subjected to dehumidification and drying treatment at 80°C for ≥4 hours until the moisture content of the granules is ≤400ppm. Then, they are vacuum sealed and packaged to obtain the finished product. Straw 4 is prepared using the same method as in Example 1.

[0090] Straws 1-4 are respectively as follows Figure 1-4 (in Figure 1 A and B are the front view and top view of straw 1, respectively. Figure 2 A and B are the front view and top view of straw 2, respectively. Figure 3 A and B are the front view and top view of straw 3, respectively. Figure 4 (A and B are the front view and top view of straw 4, respectively.) Figures 1-4 As can be seen, the straws produced by this invention can have the natural color of the plant filler itself without dyeing. The colors are natural and diverse, and there is no need to use chemical pigments, which not only enriches the choices but is also safer and healthier.

[0091] Comparative Example 1 Comparative Example 1 is a polypropylene plastic.

[0092] Comparative Example 2 Comparative Example 2 is a PLA biodegradable material.

[0093] Comparative Example 3 Comparative Example 3 is a biodegradable PBS material.

[0094] Comparative Example 4 A composite material, differing from Example 1 in that the plant filler is replaced with an equal part by weight of nanocellulose.

[0095] Comparative Example 5 A composite material, differing from Example 1 in that nanocellulose is replaced with an equal part by weight of plant filler.

[0096] Comparative Example 6 A composite material, differing from Example 1 in that the amount of nanocellulose is changed to 2 parts and the amount of plant filler is changed to 31 parts.

[0097] Comparative Example 7 A composite material, which differs from Example 4 in that the amount of nanocellulose is changed to 15 parts and the amount of plant filler is changed to 5 parts.

[0098] The raw material components and their amounts in each embodiment are shown in Table 1.

[0099] Table 1. Raw material composition of each embodiment (unit: parts by weight)

[0100] Product effectiveness test 1. Testing Method Bio-based carbon content: GB / T 39715.2-2021 "Bio-based carbon content of plastics - Part 2: Determination of bio-based carbon content".

[0101] Heat distortion temperature (HDT): Tested according to GB / T 1634.2-2019 "Determination of load distortion temperature of plastics - Part 2: Plastics, hard rubber and long fiber reinforced composites".

[0102] Tensile strength: GB / T 1040.1-2006 "Determination of tensile properties of plastics - Part 1: General".

[0103] Flexural modulus: GB / T 9341-2008 "Determination of Flexural Properties of Plastics".

[0104] Notched impact strength of cantilever beams: GB / T 1843-2008 "Determination of impact strength of plastic cantilever beams".

[0105] The agricultural waste content in the products obtained in each embodiment and comparative example = mass of plant filler / mass of bio-based raw materials in bio-based materials × 100%, where "bio-based raw materials in bio-based materials" refers to the bio-based raw materials used in the product and does not include non-bio-based raw materials, such as PHB, P34HB, plant filler, and nanocellulose, which are all bio-based raw materials, while nucleating agents, coupling agents, and antioxidants are non-bio-based raw materials.

[0106] 2. Test Results The performance test results of each embodiment and comparative example are shown in the table below.

[0107] Table 2 Performance test results of each embodiment and comparative example

[0108] As shown in the table above, the bio-based carbon content of the materials provided in Examples 1-4 of this invention all reach over 95%, the heat distortion temperature reaches 103-117℃, and they exhibit excellent high-temperature resistance and thermoplastic processability. Simultaneously, the tensile strength reaches 28-33 MPa, the flexural modulus reaches 1782-1994 MPa, the cantilever beam notched impact strength reaches 3.8-4.5 MPa, and they possess good toughness, excellent mechanical properties, and good processability. Furthermore, they utilize agricultural waste as raw material, resulting in a high agricultural waste content, which improves the utilization rate of agricultural waste and significantly reduces costs. Moreover, since the raw materials used are biodegradable bio-based materials, they do not contain petrochemical components and can degrade in the natural environment, achieving full biodegradability (such as marine degradation, household composting degradation, freshwater degradation, soil degradation, etc.).

[0109] Comparative Example 1's PP is a petroleum-based plastic derived from non-renewable fossil fuels (oil / natural gas), which is not only non-degradable but also has poor heat resistance.

[0110] The PLA in Comparative Example 2 is not degradable in the natural environment, but can only be degraded by industrial composting, and it has poor heat resistance.

[0111] The PBS in Comparative Example 3 is not degradable in the natural environment and can only be degraded by home composting. It also has poor heat resistance and is too tough to be used as a straw.

[0112] Compared with Example 1, Comparative Example 4 does not contain plant fillers, and accordingly loses the function of blocking crack propagation when the material is impacted, resulting in a decrease in the impact strength of the material and making the material brittle.

[0113] Compared with Example 1, Comparative Example 5 does not contain nanocellulose, and accordingly loses the reinforcing and stiffening effect of the supporting skeleton, resulting in a decrease in the flexural modulus and tensile strength of the material, making the material less stiff and weaker.

[0114] Compared with Example 1, Comparative Example 6 has a slight decrease in toughness, stiffness and strength due to the simultaneous reduction of plant filler and nanocellulose, and the content of agricultural waste is also slightly reduced.

[0115] Compared to Example 4, Comparative Example 7, due to the reduction in plant filler content and the increase in nanocellulose content, resulted in a cantilever beam notched impact strength of less than 3.5 kJ / m. 2 The material is too brittle and does not meet the requirements for application, such as being unsuitable for use as a straw.

Claims

1. A bio-based material, characterized in that, Based on parts by weight, it includes the following raw material components: 50-80 parts of polyhydroxy fatty acid ester 6-40 parts of plant filler 3-14 parts of nanocellulose; The polyhydroxy fatty acid ester is a copolymer of poly(3-hydroxybutyric acid) and poly(3-hydroxybutyric acid) with 4-hydroxybutyrate. The plant filler is in granular form.

2. The bio-based material according to claim 1, characterized in that, The poly(3-hydroxybutyric acid) has a weight-average molecular weight of 600,000 to 1,000,000, and / or the poly(3-hydroxybutyric acid) copolymer of 4-hydroxybutyrate has a weight-average molecular weight of 400,000 to 800,000.

3. The bio-based material according to claim 1, characterized in that, The mass ratio of poly(3-hydroxybutyric acid) and poly(3-hydroxybutyric acid) copolymer 4-hydroxybutyrate is 1:1 to 1:

4.

4. The bio-based material according to claim 1, characterized in that, The average particle size of the plant filler is 20 to 200 mesh.

5. The bio-based material according to claim 1, characterized in that, The average fiber length of the nanocellulose is ≤1000μm, and / or the average fiber diameter of the nanocellulose is ≤60μm.

6. The bio-based material according to claim 1, characterized in that, The plant filler is at least one of pandan powder, wood powder, bamboo powder, sugarcane bagasse, coffee grounds, tea leaves, alfalfa powder, peanut shell powder, and walnut shell powder.

7. The bio-based material according to claim 1, characterized in that, The weight ratio of the plant filler to nanocellulose is 1:1 to 2:

1.

8. The method for preparing the bio-based material according to any one of claims 1-7, characterized in that, Includes the following steps: The raw material components are mixed, melt-blended and granulated, and then post-processed to obtain the bio-based material.

9. The preparation method according to claim 8, characterized in that, The melt blending and granulation is carried out in a parallel twin-screw extruder, with polyhydroxyalkanoates, plant fillers, and nanocellulose fed from different feed ports of the parallel twin-screw extruder.

10. The use of the bio-based material according to any one of claims 1-7 in the preparation of biodegradable tableware, biodegradable packaging materials, biodegradable decorative materials or biodegradable textiles.

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