Biodegradable high-toughness PHB / PEO material and preparation method thereof

Abstract

The invention relates to the field of biodegradable materials, in particular to a biodegradable high-toughness PHB / PEO material and a preparation method thereof.The biodegradable high-toughness PHB / PEO material comprises, by weight, 60-80% of PHB, 20-40% of PEO, 3-5% of a compatibilizer, 1-2% of a plasticizer and 5-8% of a degradation accelerator, the PHB is a microbial fermentation product with the purity larger than 98%, the PEO is ultra-high molecular weight PEO with the molecular weight larger than 98%, and the compatibilizer is a biodegradable high-toughness PHB / PEO material. The PHB, the PEO, the compatibilizer, the plasticizer and the degradation accelerant are blended and then subjected to heat treatment at the temperature of 100 DEG C, internal stress is released, annealing treatment is conducted, PEO crystal orientation is induced through water-cooling traction, a crystal separation structure is optimized, the tensile strength and modulus are improved, ultra-high molecular weight PEO with the molecular weight larger than that of the PEO is selected as a toughening phase, impact energy is dissipated through molecular chain entanglement and entropy elasticity, and the tensile strength and modulus are improved. The breaking elongation 1t of pure PHB is broken through; and the bottleneck is 10%.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biodegradable materials, in particular to a biodegradable high-toughness PHB / PEO material and a preparation method thereof. BACKGROUND

[0002] Poly-β-hydroxybutyrate (PHB) is an important member of the polyhydroxyalkanoate (PHA) family, which is a fully biodegradable polyester material synthesized by microorganisms. Its molecular chain structure has high regularity, good biocompatibility, and can be completely decomposed into water and carbon dioxide in the natural environment. Compared with petroleum-based plastics, PHB has two core environmental advantages: it can be biodegraded in various environments such as oceans, soils, and composts, and will not form permanent pollution; it does not release toxic substances such as dioxins during incineration. These characteristics make it an ideal candidate material for solving the problem of plastic pollution, especially suitable for application in short-term use scenarios such as disposable packaging, medical devices, and agricultural films.

[0003] With the tightening of global "plastic restriction" policies and the increasing environmental awareness of consumers, the market demand for biodegradable materials has shown explosive growth. According to industry application feedback, PHB has shown significant potential in the field of food packaging - it has better barrier properties than PLA, which can effectively extend the shelf life of food. Industry-leading companies such as CJ BIO have passed the US FDA food contact safety certification and applied it to food containers such as paper cup coatings and instant noodle bowls. In the biomedical field, the degradation product of PHB, β-hydroxybutyric acid, is an intermediate product of human metabolism, which gives it excellent biocompatibility and is suitable for high-end applications such as drug delivery carriers, surgical sutures, and tissue engineering scaffolds.

[0004] However, despite the ideal environmental performance and broad application prospects of PHB, its industrialization process is still severely restricted by inherent material defects. The problems of brittleness, processing difficulty, high cost, etc. have led to a much lower market share than mature bioplastics such as PLA. Breaking through these technical bottlenecks and developing high-performance PHB-based materials have become the focus of current research in the field of biodegradable materials.

[0005] PHB has a high regularity of molecular chain structure, which is easy to form large-size spherulites, resulting in significant defects in its actual application, mainly manifested in three technical bottlenecks: Mechanical performance defects: PHB exhibits typical brittle material characteristics at room temperature, with an elongation at break usually less than 5%, which cannot meet the basic requirements of most plastic products for toughness. This brittleness is due to the characteristics of high crystallinity (usually > 60%) and weak interfacial bonding between spherulites, which is prone to catastrophic fracture when subjected to impact load. High molecular materials often need to withstand dynamic loads such as transportation and falling in actual application, and the brittleness of PHB severely limits its application range.

[0006] Narrow processing window: The thermal decomposition temperature (about 180-190℃) of PHB is very close to the melting point (about 170-180℃), leaving only a narrow processing window of about 10℃. In actual extrusion or injection molding processing, a slight mistake in temperature control will cause the material to thermally degrade, resulting in pores, surface defects, or even a significant decrease in molecular weight. More seriously, PHB melt exhibits high viscosity and weak shear thinning behavior, requiring high-power processing equipment, which significantly increases production costs. This characteristic makes it difficult to directly use traditional petroleum plastic processing production lines for PHB production, restricting its industrialization process.

[0007] Insufficient thermal stability: PHB will undergo molecular chain scission if it stays at the processing temperature for a long time, resulting in a significant decrease in molecular weight and deterioration of the performance of the final product. Research data shows that the molecular weight of PHB can decrease by more than 40% at 180℃ for 30 minutes. This thermal instability imposes extremely high requirements on the temperature control accuracy of the processing equipment and also limits the complexity of the product structure and the uniformity of the wall thickness. SUMMARY

[0008] In view of the problems in the prior art, the purpose of the present application is to provide a high-toughness PHB / PEO material with balanced toughness and degradability and high processing safety, which realizes an elongation at break of >160% for PHB-based materials while maintaining a biodegradation of >70% for 90 days.

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the present application is: a biodegradable high-toughness PHB / PEO material, comprising, by weight percentage: PHB: 60-80wt%, PEO: 20-40wt%, compatibilizer: 3-5wt%, plasticizer: 1-2wt%, degradation promoter: 5-8wt%, the PHB is selected from microbial fermentation products with a purity of more than 98%, the PEO is selected from ultra-high molecular weight PEO with a molecular weight of more than After blending of the PHB, PEO, compatibilizer, plasticizer, and degradation promoter, the mixture is subjected to heat treatment at 100℃ to release internal stress and perform annealing treatment, PEO crystallization orientation is induced by water cooling traction, the crystallization separation structure is optimized, and the tensile strength and modulus are improved.

[0010] The biodegradable high-toughness PHB / PEO material described above, the compatibilizer is selected from glycidyl methacrylate grafted PEO, which forms covalent bond bridging the two phases through ring-opening reaction of the epoxy group with the ester bond of PHB, strengthening the interfacial adhesion.

[0011] The biodegradable high-toughness PHB / PEO material described above, the plasticizer is selected from epoxy soybean oil, which reduces the viscosity of the solution and improves the flexibility.

[0012] The aforementioned biodegradable high-toughness PHB / PEO material uses surface-modified nano-calcium carbonate coated with sodium stearate as the degradation promoter. The surface-modified nano-calcium carbonate is a heterogeneous nucleating agent for PHB. When it comes into contact with water, the sodium stearate dissolves, exposing the hydrophilic surface.

[0013] A method for preparing a biodegradable, high-toughness PHB / PEO material includes the following steps: Step 1: Raw material pretreatment. Dry the PHB material in 80℃ hot air for 6 hours to make its moisture content <50ppm. Dry the PEO material in 50℃ vacuum for 4 hours to make its moisture content <100ppm. Step 2: Mix the following materials by weight percentage: PHB: 60-80wt%, PEO: 20-40wt%, compatibilizer: 3-5wt%, plasticizer: 1-2wt%, degradation accelerator: 5-8wt%, and feed them into a co-rotating twin-screw extruder. Step 3: Set the temperature of each zone of the twin-screw extruder, and adjust the screw speed and the residence time of the melt in the twin-screw extruder; Step 4: Perform annealing treatment at 100℃ for 2 hours to release internal stress; Step 5: Set the traction ratio and cooling water temperature, and perform water-cooled traction to induce PEO crystallization orientation to obtain PHB / PEO material.

[0014] The above-mentioned method for preparing biodegradable high-toughness PHB / PEO material uses glycidyl methacrylate grafted PEO as the compatibilizer. The glycidyl methacrylate grafted PEO is prepared by melt grafting PEO and glycidyl methacrylate under the initiation of dicumyl peroxide at a reaction temperature of 110-130℃ to obtain PEO-g-GMA.

[0015] The above-mentioned method for preparing biodegradable high-toughness PHB / PEO material uses a co-rotating twin-screw extruder with a high-shear screw combination, L / D=40:1, a screw speed of 40-60 rpm, a melt flow rate of 15-20 g / 10 min at 170°C, and a melt residence time of <3 min.

[0016] In the above-mentioned method for preparing biodegradable high-toughness PHB / PEO material, the traction ratio is 3-5 times and the cooling water temperature is 10-15℃.

[0017] The beneficial effects of this invention, a biodegradable high-toughness PHB / PEO material and its preparation method, are: selecting materials with a molecular weight greater than [missing information]. The super high molecular weight PEO is used as a toughening phase, the molecular chain entanglement and the entropy elasticity dissipate impact energy, and the bottleneck of the elongation at break of pure PHB < 10% is broken through; the glycidyl methacrylate grafted PEO is used to make the epoxy group and the ester bond of PHB have ring-opening reaction, so that the two phases are bridged by covalent bonds, and the interface bonding energy is improved; the surface modified nano calcium carbonate is used as a heterogeneous nucleating agent of PHB, the crystallization time is shortened, and after the sodium stearate is dissolved, the hydrophilic surface is exposed to accelerate the disintegration. DETAILED DESCRIPTION

[0018] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions of the present application will be described below in combination with specific embodiments.

[0019] Pure PHB is a hard and brittle material, the elongation at break is usually < 10%, the impact resistance is poor, and brittle fracture easily occurs under stress, which cannot meet the requirements of most flexible or tough applications such as films, packaging, containers.

[0020] PHB has poor thermal stability, the melting temperature Tm ≈ 170-180°C is very close to the thermal decomposition temperature Td ≈ 250°C, resulting in a very narrow melt temperature range for processing of PHB, usually only about 10-20°C. If the temperature is slightly higher, serious thermal degradation will occur, the molecular weight will decrease, the color will change, and the performance will deteriorate. If the temperature is slightly lower, the flowability will be poor, and it will be difficult to fill the mold. At the same time, the melt strength is low, the crystallization speed is fast, and the shrinkage is large.

[0021] PHB has very high crystallinity, which leads to high brittleness and low transparency, and is usually translucent or opaque. The fast crystallization rate leads to rapid crystallization and brittleness of the product after processing and cooling, further exacerbating the brittleness problem, and may cause the product to deteriorate in performance during storage and use due to post-crystallization.

[0022] PHB is a hydrophobic crystalline polyester, and PEO is a hydrophilic crystalline polyether. Although they have a certain degree of compatibility and are partially miscible, they are not completely compatible. Simple blending can easily lead to phase separation, forming larger phase domains, and the interface adhesion is weak. This poor phase morphology can seriously weaken the mechanical properties of the blend, especially the toughness, and can lead to unstable processing and uneven product performance.

[0023] The ratio of PHB / PEO is precisely controlled, and other means such as crosslinking, nano filler reinforcement, and selection of specific compatibilizers can be combined to obtain significant toughening effect while maximizing the rigidity, strength and heat resistance of PHB, find the best balance point of toughness and rigidity, and meet the requirements of specific applications.

[0024] The melting point of PHB and PEO is quite different (about 110 °C), the melt viscosity behavior is different, and the crystallization kinetics is also different. Direct melt blending of the two requires special process control to avoid degradation of PEO due to long residence at high temperature or poor plasticization of PHB at lower temperature. The cooling process also affects the final crystallinity and phase morphology.

[0025] Both PHB and PEO are biodegradable and biocompatible materials. However, the compatibilizer, stabilizer or other additives introduced must be carefully selected to not destroy this core advantage, especially in biomedical or environmentally friendly packaging applications.

[0026] The invention patent with patent publication number CN1347372A addresses the brittleness problem of PHB by blending PHB with polyethylene oxide (PEO) and cellulose ester (CAB) to form a ternary blend, improving the material toughness while maintaining its complete natural degradability. Preparation method: first, the polyhydroxybutyrate powder is soaked in deionized water for 1-4 days, filtered and dried in an oven at 80-100 °C to constant weight. Then the raw materials and additives are mixed uniformly, the mixture is placed in a mold heated to 60-90 °C, pre-pressed in an oil press, then the mold is heated to 160-195 °C, hot pressed at a pressure of 7-12 MPa for 20-40 minutes, and finally the mold is removed when the temperature drops below 60 °C, obtaining a ternary blend. The patent proposes a degradable poly (β-hydroxybutyrate) ternary blend consisting of 70-92% poly (β-hydroxybutyrate), 4-20% polyethylene oxide (PEO), 3.5-20% cellulose ester, and 0.5-2% additives, by uniformly mixing the components, the toughness of PHB is improved while maintaining its complete natural degradability. The invention method is simple, widely applicable, and the product can be completely degraded after disposal, which is beneficial to the treatment of "white pollution", and the waste is non-toxic, which can be used as feed and fertilizer after recycling, forming a virtuous cycle of material resources.

[0027] However, the above patent processing conditions require high: the technology needs to soak PHB powder in deionized water for 1-4 days, then dry to constant weight, and hot pressing has strict requirements on temperature, pressure and time, such as heating to 160-195℃, hot pressing under 7-12Mpa pressure for 20-40 minutes, etc. The operation process is more complicated, and the processing equipment and process control requirements are higher. Limited performance improvement: although the toughness of PHB can be improved by blending, the problem of high crystallinity and brittleness of PHB itself is difficult to completely solve, and the blend may still have room temperature embrittlement phenomenon, and the toughness may gradually decrease during storage, which cannot meet the application scenarios with extremely high toughness requirements. Biodegradability may be affected: after introducing PEO, the biodegradability of PHB itself may be reduced, which makes the degradation speed in natural environment slow or incomplete, which is potentially contradictory to the complete natural degradation emphasized in the patent, especially in the field with strict biodegradability requirements, which may limit its application. There are limitations in raw material processing: PHB raw materials need to be soaked and dried, which may affect product quality if not handled properly. And the patent does not mention the processing differences of different batches and different purity of PHB raw materials. If the raw materials change in actual production, the product performance may be unstable.

[0028] PEO is easy to hydrolyze: PEO has water solubility and is easy to hydrolyze in humid environment or contact with water, which will affect the stability and service life of the blend, limiting its application in some humid environments.

[0029] The blend may still be brittle: although PEO can improve the toughness of PHB to some extent, the problem of high crystallinity and brittleness of PHB itself is difficult to completely solve. PHB blend has room temperature embrittlement phenomenon, and its toughness may gradually decrease during storage.

[0030] Narrow processing temperature range: PHB is a thermoplastic polyester with crystallinity up to 80% or more, which is easy to decompose at high temperature, and the processing temperature range is narrow. Although the addition of PEO can reduce some processing temperature, the overall processing window of the blend is still relatively narrow, and the processing conditions are more demanding, which increases the processing difficulty and cost.

[0031] Biodegradability is affected: after introducing PEO, the biodegradability of PHB itself may be reduced, which makes the degradation speed in natural environment slow or incomplete, which is contradictory to the original intention of PHB as a biodegradable material, especially in the medical field with high biodegradability requirements, which will limit its application.

[0032] It is difficult to control the crystalline morphology: PEO and PHB molecules can easily form hydrogen bonds, which can cause PEO to change from normal spherulites to ring-shaped spherulites, and the concentric rings of PHB will also appear twisted. The crystalline morphology of the blend is greatly affected by the formula ratio and temperature, which makes it difficult to control the crystalline morphology of the blend, which may lead to unstable product performance.

[0033] Example 1

[0034] To solve the above-mentioned problems of the prior art, the present application provides a biodegradable high-toughness PHB / PEO material and a preparation method. The structure, principle, action relationship and related preparation method of the high-toughness PHB / PEO material are described below.

[0035] The PHB matrix is selected from high-purity (>98%) microbial fermentation products, and the melt index is 15-20 g / 10min (170°C). The ratio range is 60-80 wt%. The function range is to provide a biodegradable skeleton and maintain the strength of the material.

[0036] The PEO toughening phase is selected from ultra-high molecular weight PEO (Mw=5× , to avoid molecular weight leading to excessive embrittlement. The ratio range is 20-40 wt%. The function range is to enhance toughness by molecular entanglement to improve elongation at break.

[0037] The compatibilizer is selected from glycidyl methacrylate grafted PEO (PEO-g-GMA).

[0038] The ratio range is 3-5 wt%. The function range is that the epoxy group reacts with the ester bond of PHB to strengthen the interfacial adhesion The plasticizer is selected from epoxy soybean oil (ESO). The ratio range is 1-2 wt%. The function range is to reduce the melt viscosity and improve the flexibility (elongation at break ↑ 50%) The degradation promoter is selected from surface-modified nano calcium carbonate (M-CaCO3, treated with sodium stearate), and the ratio range is 5-8 wt%. The function range is to accelerate environmental degradation (30-day degradation rate > 25%) and at the same time to improve the impact strength.

[0039] Process optimization: after blending, annealing treatment at 100°C is performed to optimize the crystal phase separation structure and achieve the balance of rigidity and toughness (tensile strength and modulus are simultaneously improved).

[0040] Double screw extrusion parameters: feed section 160-170°C, compression section 180-190°C, die head 190-200°C, to avoid PHB thermal degradation (decomposition temperature ≈ 250°C), while ensuring the melt flowability of PEO.

[0041] ​Formulation optimization key: PEO content > 30% to form a continuous phase, improve toughness but reduce strength; ESO excess (> 3%) will lead to increased phase separation.

[0042] Key parameter control when preparing.

[0043] 1. Raw material pretreatment.

[0044] PHB: hot air drying at 80℃ for 6h, moisture content < 50 ppm (to prevent hydrolytic degradation).

[0045] PEO: vacuum drying at 50℃ for 4h, moisture content < 100 ppm (to avoid bubbles).

[0046] 2. Melt blending extrusion.

[0047] Equipment: co-rotating twin-screw extruder (L / D = 40:1, high shear screw combination).

[0048] Temperature zoning (℃) as shown in Table 1.

[0049] Table 1: Temperature of each zone of co-rotating twin-screw extruder .

[0050] Screw speed: 40-60 rpm (high shear leads to the risk of PHB degradation).

[0051] Residence time: < 3 min (PHB half-life is only 5 min when the temperature is > 180℃).

[0052] Post-processing technology: annealing treatment: 100℃ heat treatment for 2h → release internal stress, improve crystallization uniformity (spherulite size decreases by 30%). Water cooling stretching: stretching ratio 3-5 times, cooling water temperature 10-15℃ → induce PEO crystal orientation, improve longitudinal strength.

[0053] Industrialization key: Preferably use modular twin-screw extruder to achieve temperature control accuracy ±1℃.

[0054] PEO accounts for 60% of the cost of raw materials, and it is recommended to use recycled PEO to reduce costs.

[0055] Expand to PLA / PHB / PEO ternary system to further improve rigidity (tensile strength > 45 MPa).

[0056] Specifically, the technical scheme of the present embodiment compared with the prior art includes the following aspects.

[0057] 1. Mechanical properties, as shown in Table 2.

[0058] Table 2: Comparison of mechanical properties .

[0059] Optimization mechanism: Hydrogen bond toughening: C=O of PHB forms hydrogen bond with O-H of PEO (infrared shift to 1710 cm⁻¹), dissipating impact energy.

[0060] Nanodispersed phase: PEO-g-GMA reduces the size of PEO dispersed phase to 200-500 nm, inducing silver shear band.

[0061] 2, degradation performance, as shown in Table 3.

[0062] Table 3: Comparison table of degradation performance .

[0063] Degradation mechanism: PEO dissolution: hydrophilic PEO dissolves in water to form microchannels, accelerating microbial contact with PHB matrix.

[0064] M-CaCO3 effect: after the dissolution of the sodium stearate coating layer, the hydrophilic surface is exposed, promoting disintegration.

[0065] 3, thermal properties and processability, as shown in Table 4.

[0066] Table 4: Comparison table of thermal properties and processability .

[0067] 4, performance comparison and product advantage, as shown in Table 5.

[0068] Table 5: Performance comparison and product advantage table .

[0069] In the technical scheme of the embodiment, through the toughening of ultra-high molecular weight PEO, the interfacial strengthening of reactive compatibilizer, and the degradation synergy of nano calcium carbonate, the elongation at break of the PHB-based material is >160% (pure PHB is only 5%), while maintaining biodegradability.

[0070] Toughness / degradation balance: elongation at break >160% and 90-day degradation >70%, better than PLA-based blends.

[0071] Processing safety: low temperature extrusion (≤175℃) avoids PHB thermal degradation, preserving molecular weight integrity.

[0072] Compared with the prior art, the technical scheme of the embodiment has the following advantages.

[0073] 1, ultra-high toughness breakthrough, as shown in Table 6.

[0074] Table 6: Toughness comparison table .

[0075] Advantage: The elongation at break is 16-25 times that of pure PHB, and the degradation rate is faster than that of PCL / PLA system.

[0076] 2. Synergistic optimization of degradation rate and mechanical properties, as shown in Table 7.

[0077] Table 7: Synergistic optimization comparison table .

[0078] Advantage: While the degradation rate is increased by 2 times, the tensile strength is maintained at ≥80%.

[0079] 3. The processing thermal stability is significantly improved, as shown in Table 8.

[0080] Table 8: Thermal stability comparison table .

[0081] Advantage: By low-temperature precise temperature control and nitrogen protection, the thermal degradation of PHB is inhibited to the minimum level.

[0082] Example 2

[0083] This example describes a specific preparation method.

[0084] A preparation method of a biodegradable high-toughness PHB / PEO material, comprising the following steps: Step 1: Raw material pretreatment, dry PHB material in 80℃ hot air for 6h, so that its water content <50ppm, dry PEO material in 50℃ vacuum for 4h, so that its water content <100ppm.

[0085] Select Mw=5×10 6 PEO as toughening phase (20-40 wt%), through molecular chain entanglement and entropy elasticity dissipation impact energy, break through the bottleneck of pure PHB elongation at break <10% (improve to >160%).

[0086] Different from conventional technology: exclude PEO with molecular weight <10 5 (easy to brittle), and when PEO content >30%, form nanoscale continuous phase dispersion.

[0087] Step 2: According to the weight percentage: PHB: 60-80wt%, PEO: 20-40wt%, compatibilizer: 3-5wt%, plasticizer: 1-2wt%, degradation promoter: 5-8wt%, mix the materials into the co-rotating twin screw extruder, and use high shear screw combination.

[0088] The compatibilizer is selected from glycidyl methacrylate grafted PEO, which is prepared by melt grafting PEO with glycidyl methacrylate at a reaction temperature of 110-130°C under the initiation of dicumyl peroxide.

[0089] The epoxy group (GMA) undergoes ring-opening reaction with the ester bond of PHB to form a covalent bond to bridge the two phases; when the grafting rate is greater than or equal to 15%, the interfacial binding energy is increased by 3 times (as evidenced by the shift of the infrared C=O peak to 1710 cm⁻¹) Step 3: The cylinder is protected by N2 gas (flow rate of 0.5-1 L / min), the temperature of each zone of the twin-screw extruder is set as shown in Table 1 of Example 1, and the screw speed and the residence time of the melt in the twin-screw extruder are adjusted according to the description in Example 1.

[0090] The co-rotating twin-screw extruder has an L / D of 40:1, the screw speed is 40-60 rpm, the flow rate of the melt is 15-20 g / 10 min at 170°C, and the residence time of the melt is less than 3 min.

[0091] The melt zone temperature is less than or equal to 175°C (critical point of PHB thermal degradation), and the N2 protective gas and short residence time (<3 min) are used to control the PHB molecular weight drop rate to be less than 5%.

[0092] Step 4: Annealing treatment is performed at a temperature of 100°C for 2 h to release internal stress.

[0093] Step 5: The draw ratio and cooling water temperature are set to induce PEO crystallization and orientation by water cooling traction, and the PHB / PEO material is obtained.

[0094] The draw ratio is 3-5 times, and the cooling water temperature is 10-15°C.

[0095] By using the PEO-g-GMA compatibilizer (grafting rate ≥15%), the epoxy group is covalently bonded to the ester bond of PHB; the size of the dispersed phase is reduced to 200-500 nm, the interfacial binding energy is increased by 3 times, and the problem of easy phase separation (dispersed phase >1 μm) in the prior art PHB / PEO direct blending → large fluctuation of mechanical properties is solved.

[0096] Through the synergy of multifunctional additives, M-CaCO3 (modified with sodium stearate): simultaneously acts as a heterogeneous nucleating agent to reduce the crystallization time by 30% + a degradation accelerator (hydrophilic exposure promotes disintegration); compared with unmodified CaCO3: impact strength is increased by 20%, and degradation rate is increased by 40%.

[0097] The biodegradable high-toughness PHB / PEO material in Example 1 is prepared using the method described in this example, and the processing applicability is widened, as shown in Table 9.

[0098] Table 9: Processability broadening comparison table .

[0099] The above examples are only to illustrate the structural concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the essence of the present application should be covered within the protection scope of the present application.

Claims

1. A biodegradable high toughness PHB / PEO material characterized in that, According to the weight percentage, it comprises: PHB: 60-80wt%, PEO: 20-40wt%, compatibilizer: 3-5wt%, plasticizer: 1-2wt%, degradation promoter: 5-8wt%, the PHB is selected from microbial fermentation product with purity greater than 98%, the PEO is selected from ultra-high molecular weight PEO with molecular weight greater than After blending of the PHB, PEO, compatibilizer, plasticizer and degradation promoter, heat treatment at 100 DEG C, annealing treatment for releasing internal stress, water cooling traction for inducing PEO crystallization orientation, optimization of crystallization separation structure, and improvement of tensile strength and modulus.

2. The biodegradable, high-toughness PHB / PEO material of claim 1, wherein, The compatibilizer is glycidyl methacrylate grafted PEO, which forms covalent bond bridge between two phases by ring-opening reaction of epoxy group and PHB ester bond, and strengthens interfacial adhesion.

3. The biodegradable, high-toughness PHB / PEO material of claim 1, wherein, The plasticizer is epoxy soybean oil, which reduces the viscosity of the solution and improves flexibility.

4. The biodegradable, high-toughness PHB / PEO material of claim 1, wherein, The degradation promoter is surface modified nano calcium carbonate coated by sodium stearate, which is a heterogeneous nucleating agent for PHB. When water is encountered, sodium stearate dissolves, exposing a hydrophilic surface.

5. A process for the preparation of a biodegradable high toughness PHB / PEO material, characterized in that, The method comprises the following steps: Step 1: raw material pretreatment, drying PHB material in hot air at 80℃ for 6h, so that its water content is <50ppm, drying PEO material in vacuum at 50℃ for 4h, so that its water content is <100ppm; Step 2: mixing materials according to weight percentage: PHB: 60-80wt%, PEO: 20-40wt%, compatibilizer: 3-5wt%, plasticizer: 1-2wt%, degradation promoter: 5-8wt% into a co-rotating twin screw extruder; Step 3: setting the temperature of each zone of the twin screw extruder, adjusting the screw speed and the residence time of the melt in the twin screw extruder; Step 4: annealing treatment at 100℃ for 2h to release internal stress; Step 5: setting the pulling ratio and cooling water temperature, water-cooled traction to induce PEO crystallization orientation, and obtaining PHB / PEO material.

6. The method of producing a biodegradable, high-toughness PHB / PEO material according to claim 5, characterized in that, The compatibilizer is glycidyl methacrylate grafted PEO, which is prepared by melt grafting PEO with glycidyl methacrylate at a reaction temperature of 110-130℃ under the initiation of dicumyl peroxide.

7. The method of producing a biodegradable, high-toughness PHB / PEO material according to claim 5, characterized in that, The co-rotating twin screw extruder uses a high shear screw combination, L / D=40:1, the screw speed is 40-60rpm, the flow rate of the melt is 15-20g / 10min at 170℃, and the residence time of the melt is <3min.

8. The method for preparing the biodegradable high-toughness PHB / PEO material according to claim 5, characterized in that, The pulling ratio is 3-5 times, and the cooling water temperature is 10-15℃.

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