High-efficiency low-energy-consumption granulation process and system for full-biodegradable multiphase composite material

Abstract

The invention relates to the field of high polymer material processing, and discloses a high-efficiency low-energy-consumption granulation process and system for a full-biodegradable multiphase composite material, and the process comprises the following steps: feeding raw materials such as polypropylene carbonate, polyester, plant fibers and four-stage activated biomass hydroxyapatite into a double-screw extruder with the length-diameter ratio of not less than 64: 1 in a grading manner according to heat sensitivity; the temperature, the pressure and the shear field are cooperatively controlled, and three-section type temperature distribution of intensified melting, short-time reaction and rapid cooling is established; and carrying out three-stage gradient vacuum devolatilization and underwater pelletizing to obtain a finished product. The four-stage activated biomass hydroxyapatite is prepared by plasma etching, hydrophobic coating, interface coupling and melt pre-dispersion. The problem of degradation of heat-sensitive components is solved through graded feeding and asymmetric temperature control, the dispersity and interface bonding force of the filler are improved by utilizing a four-stage activation technology, closed-loop control is realized by combining online rheology monitoring and an energy consumption model, and continuous production of the full-biodegradable material with low energy consumption, low volatile matter and high mechanical property is realized.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing, specifically to a highly efficient and low-energy granulation process and system for fully biodegradable multiphase composite materials. Background Technology

[0002] In the manufacturing of fully biodegradable multiphase composite materials, there is a contradiction in the processing thermal history between biodegradable resin matrices such as polypropylene carbonate and biomass fillers such as plant fibers. Biodegradable resins typically require sufficient temperature and shear to achieve adequate plasticization and reaction, while natural plant fibers are highly heat-sensitive and prone to thermal degradation, carbonization, or discoloration under prolonged high-temperature shear conditions. Existing extrusion granulation processes often employ single or simple gradient temperature control and frequently add resin and fibers simultaneously. This approach fails to decouple the resin melting and fiber mixing processes, often resulting in uneven resin plasticization or impaired fiber properties, thereby affecting the mechanical properties and appearance quality of the composite material.

[0003] Furthermore, inorganic functional fillers such as biomass hydroxyapatite, due to their high surface energy and hydrophilicity, exhibit interfacial compatibility differences with hydrophobic, fully biodegradable polymer matrices. Traditional surface treatment methods struggle to construct a stable and effective organic transition layer on the surface of inorganic particles, leading to a high tendency for secondary agglomeration of the filler at high filler concentrations, resulting in stress concentration points within the matrix. This uneven dispersion and weak interfacial bonding limit the reinforcing and toughening effects of inorganic fillers, making it difficult to obtain high-performance composite materials.

[0004] Meanwhile, existing continuous granulation production systems typically lack real-time feedback and energy consumption optimization mechanisms based on material rheological states. Due to batch-to-batch fluctuations in raw materials, open-loop control modes with fixed parameters struggle to guarantee consistency in key quality indicators such as melt viscosity. Furthermore, equipment operation often relies on experience-based settings, lacking quantitative model control of the relationship between shear heat and mechanical energy conversion. This results in excessive mechanical energy input and ineffective heat emissions during production, leading to high unit energy consumption and hindering cost control and energy conservation / emission reduction in industrial production. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a highly efficient and low-energy granulation process and system for fully biodegradable multiphase composite materials, which solves the problems of degradation of fully biodegradable materials due to heat sensitivity during processing, uneven dispersion of multiphase fillers at high filler content, and excessive energy consumption in the extrusion granulation process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a highly efficient and low-energy-consumption granulation process for fully biodegradable multiphase composite materials, comprising the following steps: S1. Prepare raw materials for polypropylene carbonate, polybutylene adipate / terephthalate, polylactic acid, polyglycolic acid modified masterbatch, plant fiber ultrafine powder, grade IV activated biomass hydroxyapatite, and additives. S2. The polypropylene carbonate, polybutylene adipate / terephthalate, polylactic acid, polyglycolic acid modified masterbatch, plant fiber ultrafine powder, fourth-grade activated biomass hydroxyapatite, and the additives are fed into a co-rotating parallel twin-screw extruder in stages according to the heat sensitivity and dispersion requirements of the raw materials. The polypropylene carbonate, polybutylene adipate / terephthalate, polylactic acid, polyglycolic acid modified masterbatch, and the additives are added through the main feed port of the co-rotating parallel twin-screw extruder. The plant fiber ultrafine powder is added through the first lateral feed port located at the front section of the barrel of the co-rotating parallel twin-screw extruder; The fourth-stage activated biomass hydroxyapatite is added through a second lateral feed port located downstream of the first lateral feed port; S3. Apply shearing and heating to each component raw material entering the co-rotating parallel twin-screw extruder, and coordinately control the temperature field, pressure field and shear field of the co-rotating parallel twin-screw extruder to plasticize and react the component raw materials to form a melt; The temperature field is sequentially divided into an enhanced melting zone, a short-time reaction zone, and a rapid cooling zone along the screw axis of the co-rotating parallel twin-screw extruder. S4. During the reactive extrusion process in step S3, the melt is subjected to multi-stage decompression devolatilization treatment through a three-stage vacuum devolatilization system. The three-stage vacuum devolatilization system includes two stages of dynamic devolatilization and one stage of static devolatilization, and the three stages of vacuum degree are distributed in a gradient increasing distribution. S5. The melt after the devolatilization treatment in step S4 is subjected to underwater pelletizing, centrifugal drying and screening to obtain finished pellets.

[0007] By adopting the above technical solution, and utilizing staged feeding combined with asymmetric temperature field control, processing conflicts caused by differences in the heat resistance of various components are avoided. The matrix resin is melted first at the main feed port, providing a liquid carrier for subsequent fillers; plant fibers are added at the front of the barrel, reducing their residence time in the high-temperature zone and preventing carbonization and discoloration; the fourth-stage activated biomass hydroxyapatite is added downstream, at which point the matrix is ​​fully plasticized, which is conducive to the wetting and dispersion of inorganic particles in the melt and reduces hard friction between particles. At the same time, the three-stage gradient devolatilization, by gradually increasing the vacuum degree and combining dynamic and static devolatilization, improves the diffusion efficiency of small molecule volatiles while preventing melt entrainment.

[0008] Preferably, the raw materials, by weight, include: 18 to 22 parts of polypropylene carbonate, 25 to 30 parts of polybutylene adipate / terephthalate, 5 to 8 parts of polylactic acid, 20 to 25 parts of polyglycolic acid modified masterbatch, 8 to 12 parts of plant fiber ultrafine powder, and 3 to 5 parts of quaternary activated biomass hydroxyapatite; the additives include: 2 to 3 parts of compatibilizer, 1 to 2 parts of lubricant, 0.3 to 0.7 parts of anti-hydrolysis agent, and 1 to 2 parts of plasticizer.

[0009] By adopting the above technical solution, the barrier properties, toughness and strength of the material are balanced by blending polypropylene carbonate, polybutylene adipate / terephthalate and polylactic acid in a specific ratio; the introduction of polyglycolic acid modified masterbatch improves the heat resistance of the material; plant fiber and biomass hydroxyapatite are used as reinforcing fillers of different dimensions to construct a mechanical support network in the matrix.

[0010] Preferably, the preparation process of the fourth-stage activated biomass hydroxyapatite includes: performing fluidized bed radio frequency plasma etching treatment on biomass hydroxyapatite powder under an oxygen atmosphere, setting the power to 200-400W and the treatment time to 5-15 minutes, to obtain a surface active site density of 5-8 sites / nm. 2 The first intermediate is coated with stearic acid at a temperature of 80-95°C for 1-3 hours to obtain a hydrophobically modified second intermediate with a contact angle of not less than 110 degrees. The second intermediate is then grafted onto an alcohol-water mixture with a pH adjusted to 8.0-9.0 using a silane coupling agent at a reaction temperature of 60-80°C to obtain a grafting density of 1.5-2.5 molecules / nm. 2 The third intermediate is obtained by interfacial coupling modification; the third intermediate is melt-blended and crushed with polypropylene carbonate resin at 120-140℃ to obtain the fourth-level activated biomass hydroxyapatite with a core-shell structure.

[0011] By employing the above technical solution, this invention designs a layer-by-layer progressive filler modification mechanism. First, radio frequency plasma etching is used to increase the specific surface area of ​​biomass hydroxyapatite and generate highly active free radical sites. Second, stearic acid molecules preferentially occupy some high-energy sites to form a hydrophobic isolation layer, preventing powder agglomeration before subsequent chemical reactions. Third, chemical grafting of a silane coupling agent with the remaining active sites is initiated under a specific pH environment, establishing an inorganic-organic chemical bonding bridge. Finally, a layer of polypropylene carbonate resin is pre-coated onto the filler surface through melt blending, forming a core-shell structure. This structure reduces the interfacial tension between the filler and the matrix during final granulation, promoting uniform dispersion.

[0012] Preferably, in step S2: the melt temperature at the location where the plant fiber ultrafine powder is added is controlled between 145-155°C; the melt temperature at the location where the fourth-stage activated biomass hydroxyapatite is added is controlled between 155-160°C; and the fourth-stage activated biomass hydroxyapatite undergoes only one temperature-controlled zone thermal history before entering the short-time reaction zone.

[0013] By employing the above technical solution, targeted temperature control is implemented based on the thermal sensitivity of different fillers. Lower temperatures protect the structural integrity of plant fibers, while controlling the thermal history of the quaternary activated biomass hydroxyapatite preserves the activity of its surface grafted molecules, ensuring that interfacial reactions mainly occur after entering the short-time reaction zone, thereby improving reaction efficiency.

[0014] Preferably, the length-to-diameter ratio of the co-rotating parallel twin-screw extruder is not less than 64:1; the screw speed of the co-rotating parallel twin-screw extruder is controlled between 400-600 rpm, and the weighted average shear rate is controlled between 2000-4000 s. -1 The pressure field configuration of the co-rotating parallel twin-screw extruder is configured to maintain a melt pressure of 8-12 MPa in the short-time reaction zone; the fourth-stage activated biomass hydroxyapatite undergoes high-shear treatment with a dispersion energy density of 2.5-3.5 kJ / kg after being added to the co-rotating parallel twin-screw extruder.

[0015] By adopting the above technical solution, the large aspect ratio provides the necessary physical space for multi-step reactions and devolatilization. By controlling the screw speed and shear rate, a high-pressure environment is established in the reaction zone, increasing the probability of collisions between molecular chains and promoting interfacial chemical reactions. Limiting the dispersion energy density range ensures that inorganic particles achieve micro-nano-level dispersion while preventing excessive mechanical shear energy from causing polymer molecular chain breakage and degradation.

[0016] Preferably, the temperature field control strategy is as follows: the temperature of the enhanced melting zone is controlled between 130-160℃, and the heating gradient is controlled at 25-30℃ per aspect ratio; the temperature of the short-time reaction zone is kept constant between 162-168℃, and the fluctuation range is controlled within ±1.5℃; the temperature of the rapid cooling zone is controlled between 158-125℃, and the cooling gradient is controlled at 40-45℃ per aspect ratio.

[0017] By adopting the above technical solutions, the high heating rate of the molten zone is enhanced to rapidly melt the resin through heat conduction, reducing heat generation from mechanical friction; the constant temperature reaction zone provides a stable thermodynamic environment to ensure the consistency of the chemical grafting reaction; and the rapid cooling zone quickly removes the heat from the melt, stops possible reverse degradation reactions, and reduces the cooling load of the subsequent pelletizing process.

[0018] Preferably, in step S4: the vacuum degree of the first-stage dynamic devolatilization port is controlled at -0.090 to -0.095 MPa; the vacuum degree of the second-stage dynamic devolatilization port is controlled at -0.095 to -0.098 MPa; the vacuum degree of the static devolatilization port is controlled at -0.092 to -0.096 MPa; the melt flow channel at the static devolatilization port adopts a porous flow divider structure to increase the exposed area of ​​the melt.

[0019] By adopting the above technical solution, a large amount of volatile components are removed in advance by a lower vacuum level in the front stage to prevent material entrainment due to excessive gas velocity; the high vacuum level in the rear stage is used for deep removal of non-volatile components. The static devoluting port uses a porous flow divider to divide the melt into fine streams, which greatly increases the specific surface area of ​​the melt and improves the removal rate of residual monomers and moisture based on the diffusion principle.

[0020] Preferably, the process further includes an online quality monitoring step, wherein the online quality monitoring step measures the melt pressure drop and flow rate through the standard capillary in real time using a bypass rheological measurement module; calculates the apparent shear viscosity of the melt in real time based on the melt pressure drop, the flow rate, and the geometric dimensions of the standard capillary; compares the calculated apparent shear viscosity with a preset target viscosity range, and adjusts the temperature control system and screw speed of the co-rotating parallel twin-screw extruder based on the comparison result.

[0021] By adopting the above technical solution, a feedback control mechanism based on melt rheological properties was established. Apparent shear viscosity can reflect the molecular weight distribution and plasticization degree of the material. By monitoring this parameter in real time and adjusting the process parameters accordingly, the impact of raw material batch fluctuations on product quality can be compensated in a timely manner, ensuring the uniformity of product performance.

[0022] Preferably, the process further includes an energy consumption closed-loop control step, which includes: establishing a specific mechanical energy consumption prediction model, wherein the specific mechanical energy consumption prediction model is configured to obtain a specific mechanical energy consumption value by weighted summation of shear energy consumption component, pressure energy consumption component, and time energy consumption component; wherein the shear energy consumption component is established based on melt viscosity function and shear rate, the pressure energy consumption component is established based on pressure drop during extrusion and total feed rate, and the time energy consumption component is established based on material residence time; the specific mechanical energy consumption value is calculated in real time, and when the calculated specific mechanical energy consumption value deviates from a preset threshold, the heating power and motor frequency of each zone of the co-rotating parallel twin-screw extruder are adjusted.

[0023] By adopting the above technical solution, specific mechanical energy consumption is used as a key control indicator. By quantifying the contribution weight of different process parameters to total energy consumption through a model, the system can automatically adjust heating power and motor speed while meeting product quality requirements, finding the operating condition with the lowest energy consumption, and reducing ineffective heat energy emissions and excess mechanical energy input.

[0024] Secondly, the present invention provides a highly efficient and low-energy-consumption granulation system for fully biodegradable multiphase composite materials, comprising: The unit includes a plant fiber pretreatment and ultrafine grinding unit, a multi-channel precision feeding and gradient reaction devolatilization granulation unit, an online quality detection unit, and a central intelligent control unit.

[0025] The plant fiber pretreatment and ultrafine grinding unit integrates a hot air circulating dryer, a vertical turbine mill, a high-efficiency turbine classifier, and a powder surface modification module that includes an online low-temperature plasma treatment chamber and an atomized spray mixing chamber, arranged in series.

[0026] The multi-path precision feeding and gradient reaction devolatilization granulation unit includes a co-rotating parallel twin-screw extruder with an aspect ratio of not less than 64:1 and a feeding device. The barrel of the co-rotating parallel twin-screw extruder is provided with a main feed port along the axial direction, a first lateral feed port located at the front section of the barrel, a second lateral feed port located downstream of the first lateral feed port, and two-stage dynamic devolatilization and one-stage static devolatilization respectively connected to a vacuum pump group.

[0027] The online quality inspection unit includes a bypass rheological measurement module connected to the front flow channel of the co-rotating parallel twin-screw extruder die.

[0028] The central intelligent control unit is bidirectionally connected to the multi-channel precision feeding and gradient reaction devolatilization granulation unit and the online quality detection unit.

[0029] By adopting the above technical solutions, the system achieves continuous and intelligent production from raw material pretreatment to finished product granulation. The plant fiber pretreatment unit integrates drying, crushing, grading, and surface modification into the same online process, avoiding moisture absorption and agglomeration of ultrafine powders during transport. Multi-feeding and an ultra-large aspect ratio extruder enable zoned processing of different components. The central intelligent control unit, combining online rheological monitoring data and energy consumption models, performs dual closed-loop control of the entire system, ensuring the quality stability and energy efficiency of the fully biodegradable material production process.

[0030] This invention provides a highly efficient and low-energy-consumption granulation process and system for fully biodegradable multiphase composite materials. It offers the following advantages: 1. This invention effectively solves the processing contradiction between the melting of fully biodegradable resin matrix and the thermal degradation of heat-sensitive plant fibers by combining a graded feeding strategy based on the thermal sensitivity and dispersion requirements of materials with asymmetric temperature field synergistic control. Plant fibers with poor heat resistance and activated hydroxyapatite with high surface energy are added after the matrix resin is completely melted. The melt is used as a carrier for wetting and dispersion. Combined with a three-stage temperature control of enhanced melting, short-time reaction and rapid cooling, carbonization and discoloration of fibers at high temperatures are avoided. At the same time, the uniform dispersion of multiphase components in the melt is ensured, thereby improving the overall mechanical properties and appearance quality of the composite material.

[0031] 2. This invention improves the interfacial compatibility between inorganic fillers and fully biodegradable resin matrices by preparing and applying a four-stage activated biomass hydroxyapatite with a core-shell structure including plasma etching, stearic acid hydrophobic shielding, silane coupling agent chemical bridging, and melt pre-dispersion. The stepwise modification process not only increases the density of active sites on the filler surface but also constructs an organic transition layer on the surface of inorganic particles, significantly reducing the surface energy of the filler and preventing secondary agglomeration under high filler content. This allows the composite material to achieve an excellent balance of strength and toughness while maintaining biodegradability.

[0032] 3. This invention achieves dual optimization of quality consistency and energy utilization efficiency in the granulation process by integrating online quality monitoring based on bypass rheological measurement and closed-loop energy consumption control based on a specific mechanical energy consumption prediction model. The system can adjust the extrusion process parameters in real time based on changes in the apparent viscosity of the melt to offset the impact of raw material batch fluctuations. At the same time, it dynamically adjusts the heating power and motor frequency based on the energy consumption model to reduce ineffective heat emissions and excess mechanical energy input, thereby reducing the unit energy consumption of the production process while ensuring product quality indicators. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall architecture of a fully biodegradable multiphase composite material high-efficiency and low-energy granulation system according to an embodiment of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, preparation examples, embodiments, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Preparation Examples 1-3: Preparation Example 1: This preparation example provides a method for preparing fourth-level activated biomass hydroxyapatite (Modified Bio-HAP A), including the following steps: Plasma activation: Bio-HAP powder is placed in the reaction chamber of a fluidized bed radio frequency plasma treatment device, and the vacuum level is reduced to below 10 Pa. Oxygen with a purity ≥99.5% is introduced, and the gas flow rate is adjusted to stabilize the chamber pressure. The plasma generator is started, and the power is set to 300W (corresponding to a power density of 4W / cm³). 3 The surface was treated for 10 minutes. After treatment, the surface active site density was 6.5 sites / nm. 2 Bio-HAP intermediate IA with a surface energy of 67.5 mN / m.

[0036] Hydrophobic modification: Bio-HAP intermediate IA was transferred to a high-speed mixer equipped with a heating jacket and preheated to 87.5°C. 1.5% stearic acid by mass was added, and the mixture was stirred at 87.5°C and 1500 rpm for 2 hours to coat the target layer. After cooling, Bio-HAP intermediate II-A with a water contact angle of 112° and a stearic acid monolayer coverage of 88% was obtained.

[0037] Interfacial coupling: Bio-HAP intermediate II-A was dispersed in a mixed solvent of anhydrous ethanol and deionized water (95:5, volume ratio), the pH was adjusted to 8.5, and 2.0% (w / w) of silane coupling agent KH-550 was added. The mixture was heated to 70°C and reacted at this temperature for 2 hours with mechanical stirring. The reaction product was centrifuged, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 80°C for 12 hours to obtain a surface grafting density of 2.0 molecules / nm. 2 Interfacial coupling modified Bio-HAP intermediate Ⅲ-A with a grafting efficiency of 95%.

[0038] Pre-dispersion treatment: Bio-HAP intermediate III-A was mixed with polypropylene carbonate (PPC) resin (number average molecular weight 1.5 × 10⁻⁶). 5 The mixture was added to a mixer at a mass ratio of 1:4 and melt-blended at 130°C for 20 minutes. After cooling and crushing, the material was used to obtain fourth-grade activated biomass hydroxyapatite (Modified Bio-HAP A), with a core-shell structure integrity of 92%.

[0039] Preparation Example 2: This preparation example provides a method for preparing fourth-level activated biomass hydroxyapatite (Modified Bio-HAP B), including the following steps: Plasma activation: Place the raw biomass hydroxyapatite (Bio-HAP) powder in a plasma treatment device, evacuate to below 10 Pa, introduce oxygen with a purity ≥99.5% and adjust the flow rate to stabilize the chamber pressure. Start the plasma generator and set the power to 200W (corresponding to a power density of 3W / cm³). 3 After processing for 5 minutes, a surface active site density of 5.0 sites / nm was obtained. 2 IB, a Bio-HAP intermediate with a surface energy of 65 mN / m.

[0040] Hydrophobic modification: Bio-HAP intermediate IB was transferred to a high-speed mixer equipped with a heating jacket and preheated to 80°C. 1.5% stearic acid by mass was added, and the mixture was stirred at 80°C and 1500 rpm for 1 hour to coat the target material. After cooling, Bio-HAP intermediate II-B with a water contact angle of 110° and a stearic acid monolayer coverage of 85% was obtained.

[0041] Interfacial coupling: Bio-HAP intermediate II-B was dispersed in a mixed solvent of anhydrous ethanol and deionized water (95:5, volume ratio), the pH was adjusted to 8.0, and 1.0% (w / w) of silane coupling agent KH-550 was added. The mixture was heated to 60°C and reacted at this temperature for 2 hours with mechanical stirring. The reaction product was centrifuged, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 80°C for 12 hours to obtain a surface grafting density of 1.5 molecules / nm. 2 Interfacial coupling modified Bio-HAP intermediate Ⅲ-B with a grafting efficiency of 90%.

[0042] Pre-dispersion treatment: Bio-HAP intermediate III-B was mixed with polypropylene carbonate (PPC) resin (number average molecular weight 1.2 × 10⁻⁶). 5 The mixture was added to a mixer at a mass ratio of 1:4 and melt-blended at 120°C for 15 minutes. After cooling and crushing, the material was used to obtain fourth-grade activated biomass hydroxyapatite (Modified Bio-HAP B), with a core-shell structure integrity of 90%.

[0043] Preparation Example 3: This preparation example provides a method for preparing fourth-level activated biomass hydroxyapatite (Modified Bio-HAP C), including the following steps: Plasma activation: Bio-HAP powder is placed in the reaction chamber of a fluidized bed radio frequency plasma treatment device. The chamber is evacuated to below 10 Pa, and oxygen with a purity ≥99.5% is introduced, with the flow rate adjusted to stabilize the chamber pressure. The plasma generator is then started, and the power is set to 400W (corresponding to a power density of 5W / cm³). 3After processing for 15 minutes, a surface active site density of 8.0 sites / nm was obtained. 2 Bio-HAP intermediate IC with a surface energy of 70 mN / m.

[0044] Hydrophobic modification: Bio-HAP intermediate IC was transferred to a high-speed mixer equipped with a heating jacket and preheated to 95°C. 1.5% stearic acid by mass was added, and the mixture was stirred at 95°C and 1500 rpm for 3 hours to coat the target material. After cooling, Bio-HAP intermediate II-C with a water contact angle of 115° and a stearic acid monolayer coverage of 90% was obtained.

[0045] Interfacial coupling: Bio-HAP intermediate II-C was dispersed in a mixed solvent of anhydrous ethanol and deionized water (95:5, volume ratio), the pH was adjusted to 9.0, and 3.0% (w / w) of silane coupling agent KH-550 was added. The mixture was heated to 80°C and reacted at this temperature for 2 hours with mechanical stirring. The reaction product was centrifuged, washed three times with anhydrous ethanol, and then dried in a vacuum oven at 80°C for 12 hours to obtain a surface grafting density of 2.5 molecules / nm. 2 Interfacial coupling modified Bio-HAP intermediate Ⅲ-C with a grafting efficiency of 98%.

[0046] Pre-dispersion treatment: Bio-HAP intermediate III-C was mixed with polypropylene carbonate (PPC) resin (number average molecular weight 1.8 × 10⁻⁶). 5 The mixture was added to a mixer at a mass ratio of 1:4 and melt-blended at 140°C for 25 minutes. After cooling and crushing, the material was used to obtain fourth-grade activated biomass hydroxyapatite (Modified Bio-HAP C), with a core-shell structure integrity of 95%.

[0047] Examples 1-3: Example 1: This embodiment provides an efficient and low-energy granulation process for fully biodegradable multiphase composite materials, using the four-stage activated biomass hydroxyapatite (Modified Bio-HAP A) prepared in Example 1, and includes the following steps: Preparation and feeding: Weigh the following raw materials according to the following weight parts: 20 parts polypropylene carbonate (PPC), 27.5 parts polybutylene adipate / terephthalate (PBAT), 6.5 parts polylactic acid (PLA), 22.5 parts polyglycolic acid (PGA) modified masterbatch, 10 parts plant fiber ultrafine powder (D50=15μm), 4 parts of the quaternary activated biomass hydroxyapatite obtained in Preparation Example 1, 2.5 parts compatibilizer, 1.5 parts lubricant, 0.5 parts anti-hydrolysis agent, and 1.5 parts plasticizer.

[0048] A multi-channel loss-in-weight weighing scale was used for precise and coordinated feeding. PPC resin, PBAT resin, PLA resin, PGA modified masterbatch, compatibilizer, lubricant, anti-hydrolysis agent and plasticizer were added through the main feed port (zone 1) of the twin-screw extruder; plant fiber ultrafine powder was added through a side forced feeder located in zone 4, and the melt temperature at the addition location was controlled at 150°C; the quaternary activated biomass hydroxyapatite obtained in Preparation Example 1 was added through a side feed port located in zone 5, and the temperature of zone 5 was controlled at 160°C to ensure that the filler underwent only a very short thermal history before entering the reaction zone.

[0049] Multi-physics co-extrusion: The mixed components are reactive extruded in a co-rotating twin-screw extruder with a length-to-diameter ratio (L / D) of 64:1, with the screw speed controlled at 500 rpm and the weighted average shear rate at 3000 s⁻¹. -1 The nano-dispersed section (front end of zone 6) after adding Bio-HAP was subjected to a 4500s time. -1 High shear force.

[0050] The temperature, pressure, and shear fields of the twin-screw extruder are controlled collaboratively, with the specific process parameters as follows: Temperature control: Establish a three-stage temperature distribution system encompassing enhanced melting, short-time reaction, and rapid cooling. Enhanced melting zone (zones 1-5): The temperatures of each zone are set to 130℃, 135℃, 145℃, 155℃, and 160℃ respectively, with a temperature gradient of 27.5℃ / L / D; Short-time reaction zone (zones 6-10): The temperature in each zone is set to 165℃, and the reaction temperature is kept stable within the range of 165±1.5℃. Rapid cooling zone (zone 11 to the die head): The temperatures of each zone are set sequentially to 158℃, 152℃, 146℃, 140℃, 135℃, 130℃, and 125℃, with a cooling gradient of 42.5℃ / L / D to rapidly cool the melt.

[0051] Pressure control: By adjusting the speed of the melt pump, the melt pressure in the reaction zone (zones 6-10) is maintained at 10MPa, and the pressure fluctuation is controlled within ±3%.

[0052] Deep devolatilization: The three-stage vacuum devolatilization system is activated to process the melt. The first-stage dynamic devolatilization port is set in zone 8, with the vacuum level controlled at -0.0925MPa; the second-stage dynamic devolatilization port is set in zone 12, with the vacuum level controlled at -0.0965MPa; and the third-stage static devolatilization port is set at the end of the extruder, with the vacuum level controlled at -0.094MPa. Through multi-stage gradient devolatilization, small molecule volatiles in the melt are fully removed.

[0053] Molding and post-processing: The extruded melt enters the underwater pelletizing system through a screen changer. The pelletizing water temperature is controlled at 45℃. After pelletizing, the pellets are centrifuged, dried, vibrated, screened, and packaged to obtain the finished product of fully biodegradable multiphase composite material pellets.

[0054] Testing showed that the specific mechanical energy consumption during the preparation process in this embodiment was 0.13 kWh / kg, and the volatile content of the obtained particles was 0.18%, with all performance indicators being excellent.

[0055] Example 2: This embodiment provides an efficient and low-energy granulation process for fully biodegradable multiphase composite materials, using the four-stage activated biomass hydroxyapatite (Modified Bio-HAP B) prepared in Preparation Example 2, and includes the following steps: Preparation and feeding: Weigh the following raw materials according to the following weight parts: 18 parts polypropylene carbonate (PPC), 25 parts polybutylene adipate / terephthalate (PBAT), 5 parts polylactic acid (PLA), 20 parts polyglycolic acid (PGA) modified masterbatch, 8 parts plant fiber ultrafine powder (D50=10μm), 3 parts of the quaternary activated biomass hydroxyapatite obtained in Preparation Example 2, 2 parts compatibilizer, 1 part lubricant, 0.3 parts anti-hydrolysis agent, and 1 part plasticizer.

[0056] A multi-channel loss-in-weight weighing scale was used for precise and coordinated feeding. PPC resin, PBAT resin, PLA resin, PGA modified masterbatch, compatibilizer, lubricant, anti-hydrolysis agent and plasticizer were added through the main feed port (zone 1) of the twin-screw extruder; plant fiber ultrafine powder was added through a side forced feeder located in zone 4, and the melt temperature at the addition location was controlled at 145°C; the quaternary activated biomass hydroxyapatite obtained in Preparation Example 2 was added through a side feed port located in zone 5, and the temperature of zone 5 was controlled at 160°C to ensure that the filler underwent only a very short thermal history before entering the reaction zone.

[0057] Multi-physics co-extrusion: The mixed components are reactive extruded in a co-rotating twin-screw extruder with a length-to-diameter ratio (L / D) of 64:1, with the screw speed controlled at 400 rpm and the weighted average shear rate at 2000 s⁻¹. -1 In this case, a 4000s time was applied to the nano-dispersed section (front end of zone 6) after adding Bio-HAP. -1 High shear force.

[0058] The temperature, pressure, and shear fields of the twin-screw extruder are controlled collaboratively, with the specific process parameters as follows: Temperature control: Establish a three-stage temperature distribution system encompassing enhanced melting, short-time reaction, and rapid cooling. Enhanced melting zone (zones 1-5): The temperatures of each zone are set to 130℃, 132℃, 142℃, 152℃, and 160℃ respectively, with a temperature gradient of approximately 25℃ / L / D; Short-time reaction zone (zones 6-10): The temperature in each zone is set to 162℃, and the reaction temperature is kept stable within the range of 162±1.0℃; Rapid cooling zone (zone 11 to the die head): The temperatures of each zone are set sequentially to 158℃, 153℃, 148℃, 143℃, 138℃, 133℃, and 125℃, with a cooling gradient of 40℃ / L / D to rapidly cool the melt.

[0059] Pressure control: By adjusting the speed of the melt pump, the melt pressure in the reaction zone (zones 6-10) is maintained at 8 MPa, and the pressure fluctuation is controlled within ±3%.

[0060] Deep devolatilization: The three-stage vacuum devolatilization system is activated to process the melt. The first-stage dynamic devolatilization port is set in zone 8, with the vacuum level controlled at -0.090MPa; the second-stage dynamic devolatilization port is set in zone 12, with the vacuum level controlled at -0.095MPa; and the third-stage static devolatilization port is set at the end of the extruder, with the vacuum level controlled at -0.092MPa. Through multi-stage gradient devolatilization, small molecule volatiles in the melt are fully removed.

[0061] Molding and post-processing: The extruded melt enters the underwater pelletizing system through a screen changer. The pelletizing water temperature is controlled at 40℃. After pelletizing, the pellets are centrifuged, dried, vibrated, screened, and packaged to obtain the finished product of fully biodegradable multiphase composite material pellets.

[0062] Testing showed that the specific mechanical energy consumption during the preparation process in this embodiment was 0.10 kWh / kg, and the volatile content of the obtained particles was 0.20%, with all performance indicators meeting the requirements.

[0063] Example 3: This embodiment provides an efficient and low-energy granulation process for fully biodegradable multiphase composite materials, using the four-stage activated biomass hydroxyapatite (Modified Bio-HAP C) prepared in Preparation Example 3, and includes the following steps: Preparation and feeding: Weigh the following raw materials according to the following weight parts: 22 parts polypropylene carbonate (PPC), 30 parts polybutylene adipate / terephthalate (PBAT), 8 parts polylactic acid (PLA), 25 parts polyglycolic acid (PGA) modified masterbatch, 12 parts plant fiber ultrafine powder (D50=20μm), 5 parts of the quaternary activated biomass hydroxyapatite obtained in Preparation Example 3, 3 parts compatibilizer, 2 parts lubricant, 0.7 parts anti-hydrolysis agent, and 2 parts plasticizer.

[0064] A multi-channel loss-in-weight weighing scale was used for precise and coordinated feeding. PPC resin, PBAT resin, PLA resin, PGA modified masterbatch, compatibilizer, lubricant, anti-hydrolysis agent and plasticizer were added through the main feed port (zone 1) of the twin-screw extruder; plant fiber ultrafine powder was added through a side forced feeder located in zone 4, and the melt temperature at the addition location was controlled at 155°C; the quaternary activated biomass hydroxyapatite obtained in Preparation Example 3 was added through a side feed port located in zone 5, and the temperature of zone 5 was controlled at 160°C to ensure that the filler underwent only a very short thermal history before entering the reaction zone.

[0065] Multi-physics co-extrusion: The mixed components are reactive extruded in a co-rotating twin-screw extruder with a length-to-diameter ratio (L / D) of 64:1, with the screw speed controlled at 600 rpm and the weighted average shear rate at 4000 s⁻¹. -1 In this case, a 5000s application was performed on the nano-dispersion section (front end of zone 6) after adding Bio-HAP. -1 High shear force.

[0066] The temperature, pressure, and shear fields of the twin-screw extruder are controlled collaboratively, with the specific process parameters as follows: Temperature control: Establish a three-stage temperature distribution system encompassing enhanced melting, short-time reaction, and rapid cooling. Enhanced melting zone (zones 1-5): The temperatures of each zone are set to 130℃, 138℃, 148℃, 158℃, and 160℃ respectively, with a temperature gradient of approximately 30℃ / L / D; Short-time reaction zone (zones 6-10): The temperature in each zone is set to 168℃, and the reaction temperature is kept stable within the range of 168±1.5℃. Rapid cooling zone (zone 11 to the die head): The temperatures of each zone are set sequentially to 158℃, 151℃, 144℃, 137℃, 133℃, 129℃, and 125℃, with a cooling gradient of 45℃ / L / D to rapidly cool the melt.

[0067] Pressure control: By adjusting the speed of the melt pump, the melt pressure in the reaction zone (zones 6-10) is maintained at 12 MPa, and the pressure fluctuation is controlled within ±3%.

[0068] Deep devolatilization: The three-stage vacuum devolatilization system is activated to process the melt. The first-stage dynamic devolatilization port is set in zone 8, with the vacuum level controlled at -0.095MPa; the second-stage dynamic devolatilization port is set in zone 12, with the vacuum level controlled at -0.098MPa; and the third-stage static devolatilization port is set at the end of the extruder, with the vacuum level controlled at -0.096MPa. Through multi-stage gradient devolatilization, small molecule volatiles in the melt are fully removed.

[0069] Molding and post-processing: The extruded melt enters the underwater pelletizing system through a screen changer. The pelletizing water temperature is controlled at 50℃. After pelletizing, the pellets are centrifuged, dried, vibrated, screened, and packaged to obtain the finished product of fully biodegradable multiphase composite material pellets.

[0070] Testing showed that the specific mechanical energy consumption during the preparation process in this embodiment was 0.15 kWh / kg, and the volatile content of the obtained particles was 0.15%, with all performance indicators being excellent.

[0071] Comparative Examples 1-5: Comparative Example 1: Compared with Example 1, the difference lies in the temperature control in the extrusion process. This comparative example does not use the three-stage temperature distribution of enhanced melting, short-time reaction, and rapid cooling. Instead, it uses the traditional quasi-isothermal process control, setting the temperature of zones 1 to 16 of the twin-screw extruder to a constant 160°C. The remaining raw material formulations and process parameters (such as rotation speed, feeding method, etc.) are the same as in Example 1.

[0072] Comparative Example 2: The difference compared to Example 1 lies in the devolatilization control. This comparative example does not use a three-stage vacuum devolatilization system, but only a single-stage vacuum devolatilization system. Only one vacuum exhaust port is set in zone 12 of the twin-screw extruder, and the vacuum degree is controlled at -0.095MPa. The first-stage dynamic devolatilization in zone 8 and the third-stage static devolatilization at the end are eliminated. The remaining raw material formulation and process parameters are the same as those in Example 1.

[0073] Comparative Example 3: The difference between this example and Example 1 lies in the use of bio-hydroxyapatite (Bio-HAP). This comparative example did not use the fourth-stage activated bio-hydroxyapatite (Modified Bio-HAP A) prepared in Example 1, but instead used commercially available raw, unactivated bio-hydroxyapatite. The other raw material formulations and process parameters were the same as in Example 1.

[0074] Comparative Example 4: Compared with Example 1, the difference lies in the timing and location of the raw material feeding. In this comparative example, the plant fiber ultrafine powder and the fourth-level activated biomass hydroxyapatite (Modified Bio-HAP A) obtained in Preparation Example 1, along with the matrix resin (PPC, PBAT, PLA, PGA modified masterbatch) and all additives, were premixed in a high-speed mixer and then added all at once through the main feed port (zone 1) of a twin-screw extruder. Lateral forced graded feeding was not used. The remaining raw material formulations and extrusion process parameters (such as temperature settings, speed, etc.) were the same as in Example 1.

[0075] Comparative Example 5: The difference between this example and Example 1 lies in the length-to-diameter ratio (L / D) of the twin-screw extruder used. This comparative example uses a conventional twin-screw extruder with an L / D ratio of 44:1 instead of a twin-screw extruder with an L / D ratio of 64:1. Due to the reduced L / D ratio, the effective reaction and residence time of the material in the barrel are correspondingly reduced. The remaining raw material formulation and process parameter settings are the same as in Example 1.

[0076] Test Example 1: This test example is used to determine various performance indicators of the fully biodegradable composite material particles prepared in Examples 1 to 3 and Comparative Examples 1 to 5.

[0077] Specific mechanical energy consumption (SME) is measured by collecting data from the extruder's main control system during stable operation of the extruder, recording the actual output power of the main motor during stable production. (kW) and total feed amount (kg / h), according to the formula Calculate specific mechanical energy consumption (SME).

[0078] The volatile content was determined by headspace gas chromatography (HS-GC). The sample was equilibrated at 120°C for 45 minutes, and the percentage of total small molecule volatiles in the headspace gas relative to the sample mass was determined.

[0079] Tensile properties were determined according to ASTM D638. The granules were injection molded into I-type specimens and conditioned at 23±2℃ for 48 hours. The tensile speed was set to 50 mm / min, and the tensile strength and elongation at break were recorded.

[0080] Bio-HAP dispersion uniformity was determined using acid etching-SEM image analysis. The area ratio of Bio-HAP aggregates (particle size > 100 nm) per unit area was calculated, and dispersion uniformity was defined as (1 - aggregate area ratio) × 100%.

[0081] The plant fiber dispersion index is obtained by separating fibers through dissolving the matrix resin and statistically analyzing the standard deviation of fiber distribution density using an optical microscope. According to the formula calculate.

[0082] The interfacial bonding strength was determined using a micro-debonding test method. The maximum debonding load of a single fiber / filler pull-out was recorded. According to the formula calculate.

[0083] The soil available phosphorus enhancement rate was determined by grinding the granules and mixing them with standard farmland soil at a mass ratio of 1:100, followed by constant temperature incubation for 180 days. The change in soil available phosphorus content was measured using the sodium bicarbonate extraction-molybdenum antimony colorimetric method, and the enhancement rate was calculated.

[0084] Biodegradation rate was calculated based on ISO 14855 standard, by incubating under controlled composting conditions (58±2℃) for 180 days and measuring carbon dioxide release.

[0085] Test data: Table 1. Preparation process and system performance test data of fully biodegradable multiphase composite materials ; Conclusion Analysis: The data in Table 1 show that, within the set process parameter range, Examples 1 to 3 have specific mechanical energy consumption ≤0.15kWh / kg, volatile content ≤0.20%, and tensile strength ≥49MPa, verifying the effectiveness of the process parameters of the present invention.

[0086] The specific mechanical energy consumption of this embodiment is lower than that of Comparative Example 1 (isothermal) and Comparative Example 5 (low aspect ratio), confirming that the three-stage temperature field of enhanced melting, short-time reaction, and rapid cooling, combined with the 64:1 aspect ratio screw, reduces energy consumption. The enhanced melting zone provides enthalpy to rapidly soften the resin and reduce viscous dissipation; the rapid cooling zone reduces ineffective heat history. At the same time, the three-stage vacuum devolatilization system utilizes the negative pressure gradient and the melt surface renewal rate in different regions to solve the problem of insufficient deep devolatilization in Comparative Example 2 (single-stage devolatilization), reducing the residual volatile matter to below 0.2%.

[0087] The Bio-HAP dispersion and interfacial strength of the examples were superior to those of Comparative Examples 3 (unactivated) and 4 (mixed feeding), verifying the necessity of four-stage activation and lateral graded feeding. Unactivated Bio-HAP (Comparative Example 3) exhibited interfacial defects due to high surface energy aggregation; mixed feeding (Comparative Example 4) caused the plant fibers to undergo long shearing, resulting in a damaged aspect ratio and competition for adsorption with the filler. The examples, through core-shell structure construction and graded introduction, formed a multi-interfacial reinforcement network in the matrix, significantly improving tensile strength.

[0088] The examples shown high soil available phosphorus enhancement and biodegradation rates. The highly dispersed Bio-HAP provided microbial attachment sites, and the released phosphorus regulated the local nutrient balance and accelerated matrix enzymatic degradation. In Comparative Example 3, filler agglomeration limited phosphorus release and microbial contact, leading to a decrease in degradation and phosphorus enhancement rates. The composite material prepared by this process combines mechanical properties with environmental benefits.

[0089] See attached document Figure 1 This invention provides a highly efficient and low-energy granulation system for fully biodegradable multiphase composite materials. The system includes a plant fiber pretreatment and ultrafine grinding unit that is physically connected and operates in sequence and in coordination, a polypropylene carbonate resin supply unit, a multi-channel precision feeding and gradient reaction devolatilization granulation unit, an online quality detection unit, and a central intelligent control unit.

[0090] The plant fiber pretreatment and ultrafine grinding unit is configured to dry, grind, classify, and surface modify raw bamboo powder or other plant fibers. The unit integrates a hot air circulating dryer, a vertical turbine mill, a high-efficiency turbine classifier, and a powder surface modification module arranged in series. The hot air circulating dryer is connected to the vertical turbine mill, and the mill and classifier form a closed-loop connection via airflow pipelines.

[0091] The vertical turbine mill's grinding chamber contains a high-speed rotating rotor disc and toothed liners fixed to the inner wall of the chamber. Multiple grinding blades are evenly distributed around the circumference of the rotor disc, and the gap between the blades and the liners is adjustable between 0.5 mm and 2.0 mm to accommodate the initial morphology of different fiber raw materials. An air inlet ring is located at the bottom of the grinding chamber, connected to a frequency-controlled Roots blower to generate a high-speed spiral upward airflow. A high-efficiency turbine classifier integrated unit is directly mounted on the top of the grinding chamber; its core component is a cage-type classifying wheel, which is independently driven by a frequency-controlled motor.

[0092] The powder surface modification module is located in the conveying pipeline at the rear end of the classifier discharge line, and includes an online low-temperature plasma treatment chamber and an atomizing spray mixing chamber connected in sequence. The inner wall of the plasma treatment chamber is equipped with dielectric barrier discharge electrodes, configured to generate low-temperature plasma to etch and activate the powder surface; the atomizing spray mixing chamber is connected to a silane coupling agent metering pump, configured to atomize the coupling agent and graft it onto the activated powder surface.

[0093] An online particle size analyzer is installed at the discharge port of the modification module. This analyzer uses laser diffraction to detect the particle size distribution data of the powder in real time. The online particle size analyzer is connected to a PLC field controller located in the plant fiber pretreatment and ultrafine grinding unit. Based on the feedback particle size data (such as the D50 value), the PLC field controller adjusts the speed of the grinding mill and classifying wheel to achieve adaptive closed-loop control of the plant fiber powder's D50 within the range of 500 mesh to 4000 mesh. The discharge port of the plant fiber pretreatment and ultrafine grinding unit is connected to the subsequent feeding system via a sealed conveying pipeline to keep the powder dry and prevent dust leakage.

[0094] The polypropylene carbonate resin supply unit is used for storing and conveying polypropylene carbonate resin raw materials. The polypropylene carbonate resin supply unit includes a temperature-controlled and dehumidified drying silo and a vacuum feeder connected to it. The output end of the vacuum feeder is connected to the main feed port of the multi-channel precision feeding and gradient reaction devolatilization granulation unit.

[0095] The multi-channel precision feeding and gradient reaction devolatilization granulation unit includes at least five independently controlled loss-in-weight weighing scales, a co-rotating parallel twin-screw extruder, and a three-stage vacuum devolatilization system.

[0096] Five loss-in-weight weighing scales are used to store and measure polypropylene carbonate resin, polybutylene adipate / terephthalate, polylactic acid, polyglycolic acid modified masterbatch, and various additives. The twin-screw extruder has a length-to-diameter ratio (L / D) of 64:1 or higher, and the barrel is divided into at least 16 independent temperature control zones along the axial direction. Each temperature control zone is equipped with an independent electric heater and cooling medium flow channel, configured to establish an asymmetric temperature field for enhanced melting, short-time reaction, and rapid cooling.

[0097] The screw assembly structure of the twin-screw extruder is designed in zones according to the requirements of a three-stage temperature and shear field. In the enhanced melting zone, the screw elements use a combination of large-lead conveying elements and kneading discs with a staggered angle of 30 degrees or 45 degrees. In the short-time reaction zone, at least two sets of counter-meshing elements or toothed mixing elements are provided to establish a high-pressure melt seal. In the rapid cooling zone, the screw elements mainly use small-lead conveying elements, combined with high-intensity cooling of the barrel. The twin-screw extruder has a lateral forced feeding port in the fourth temperature control zone to receive plant fiber ultrafine powder; and a second lateral feeding port in the fifth temperature control zone to receive biomass hydroxyapatite that has undergone four-stage activation treatment. Downstream of the second lateral feeding port is a nano-dispersion section, which consists of three sets of thin-film kneading discs with a 90-degree staggered angle, configured to provide a dispersion energy density of 2.5-3.5 kJ / kg.

[0098] The three-stage vacuum devolatilization system is physically connected to a specific location within the barrel of the twin-screw extruder, comprising two stages of dynamic devolatilization ports and one stage of static devolatilization port. Both the first and second stage dynamic devolatilization ports are located above the barrel, with rectangular openings. These openings are equipped with anti-overflow twin-screw side feeders or pressure rollers. The third stage static devolatilization port is located on the transition channel at the end of the twin-screw extruder. This transition channel is designed as a porous manifold to increase the exposed area of ​​the melt. Each of the three devolatilization ports is connected to an independent or multi-stage series vacuum pump unit via negative pressure resistant pipelines. Each pipeline is equipped with a vacuum pressure sensor and regulating valve, configured to maintain the set vacuum gradient for each stage.

[0099] The online quality inspection unit integrates a near-infrared spectrometer probe and an online melt rheometer. The near-infrared spectrometer probe acquires real-time spectral data of the melt through a high-temperature, high-pressure resistant window, configured to analyze component content and dispersion uniformity. The online melt rheometer monitors the melt's viscosity, shear modulus, and melt flow rate rheological properties in real time using capillary rheological measurement principles. The online quality inspection unit outputs digital quality characterization signals via a data bus.

[0100] The central intelligent control unit communicates bidirectionally with multiple precision feeding and gradient reaction devolatilization granulation units and online quality inspection units via industrial Ethernet or fieldbus. The central intelligent control unit includes a high-performance industrial computer or server cluster and runs digital twin modules, process optimization modules, and adaptive control modules.

[0101] The digital twin module is configured to build a virtual production line model that interacts with the physical production line in real time. The virtual production line model includes the geometric, thermodynamic, and kinetic parameters of the extruder, and calculates specific parameters based on the embedded four-dimensional collaborative control model. It can synchronously simulate the production process state based on real-time sensor data.

[0102] Specifically, the central intelligent control unit establishes a predictive model for specific mechanical energy consumption based on the following formula to quantify the contributions of shear field and pressure field to energy consumption: ; in, Indicates the specific energy consumption compared to mechanical energy consumption; , , This is a correction factor related to the equipment structure; A function representing melt viscosity in relation to shear rate and temperature; Indicates shear rate; Indicates the melt temperature; This indicates the pressure drop during the extrusion process; Indicates the total amount of feed; This indicates the residence time or dispersion time of the material.

[0103] Meanwhile, the control unit monitors the concentration change of volatiles in the melt according to the following formula in order to regulate the efficiency of the devolatilization system: ; in, This indicates the rate of change of volatile concentration over time. This indicates the instantaneous concentration of volatile components in the melt; This represents the temperature-dependent diffusion coefficient; For the Laplace operator; Represents the velocity vector of the melt flow; For gradient operators; The mass transfer coefficient; The effective devolatilization surface area per unit volume of melt; This represents the saturation concentration of volatiles under the current temperature and pressure conditions.

[0104] In addition, the control unit calculates the rheological constitutive relation of the melt according to the following formula to correct the influence of shear heat on the temperature field in real time: ; in, A function representing melt viscosity in relation to shear rate and temperature; Indicates the zero shear viscosity factor; Indicates the activation energy of the flow; is the gas constant, with a value of 8.314 J / (mol·K). Indicates the melt temperature; The time constant of the material; Shear rate; It is a non-Newtonian exponent (power-law exponent) and dimensionless.

[0105] The process optimization module embeds a deep reinforcement learning algorithm, configured to take product quality data and system energy consumption data fed back by the online quality inspection unit as input, and take minimizing specific mechanical energy consumption and maximizing product performance indicators as objective functions to calculate the optimal combination of process parameters.

[0106] The adaptive control module receives parameter commands from the process optimization module and decomposes them into control signals for heating power, motor frequency, and valve opening. These signals are then sent to each actuator to achieve closed-loop regulation with a control cycle of less than or equal to 1 second. This control loop is configured to maintain temperature control accuracy within ±0.5℃, pressure control accuracy within ±0.1MPa, and feed rate deviation within ±0.3%.

[0107] In the product packaging process, the generated granules are centrifuged, dehydrated, and vibrated before entering the finished product buffer silo. The bottom of the buffer silo is connected to a fully automatic weighing and packaging machine, equipped with a high-precision electronic scale and heat-sealing device. This machine automatically fills the bags with materials according to a preset weight (e.g., 25kg / bag), heat-seals the bag openings, and prints and attaches labels. Finally, a palletizing robot stacks the packaged finished products onto pallets, completing a fully automated production loop.

Claims

1. A highly efficient and low-energy-consumption granulation process for fully biodegradable multiphase composite materials, characterized in that, Includes the following steps: S1. Prepare raw materials for polypropylene carbonate, polybutylene adipate / terephthalate, polylactic acid, polyglycolic acid modified masterbatch, plant fiber ultrafine powder, grade IV activated biomass hydroxyapatite, and additives. S2. The polypropylene carbonate, polybutylene adipate / terephthalate, polylactic acid, polyglycolic acid modified masterbatch, plant fiber ultrafine powder, fourth-grade activated biomass hydroxyapatite, and the additives are fed into a co-rotating parallel twin-screw extruder in stages according to the heat sensitivity and dispersion requirements of the raw materials. The polypropylene carbonate, polybutylene adipate / terephthalate, polylactic acid, polyglycolic acid modified masterbatch, and the additives are added through the main feed port of the co-rotating parallel twin-screw extruder. The plant fiber ultrafine powder is added through the first lateral feed port located at the front section of the barrel of the co-rotating parallel twin-screw extruder; The fourth-stage activated biomass hydroxyapatite is added through a second lateral feed port located downstream of the first lateral feed port; S3. Apply shearing and heating to each component raw material entering the co-rotating parallel twin-screw extruder, and coordinately control the temperature field, pressure field and shear field of the co-rotating parallel twin-screw extruder to plasticize and react the component raw materials to form a melt; The temperature field is sequentially divided into an enhanced melting zone, a short-time reaction zone, and a rapid cooling zone along the screw axis of the co-rotating parallel twin-screw extruder. S4. During the reactive extrusion process in step S3, the melt is subjected to multi-stage decompression devolatilization treatment through a three-stage vacuum devolatilization system. The three-stage vacuum devolatilization system includes two stages of dynamic devolatilization and one stage of static devolatilization, and the three stages of vacuum degree are distributed in a gradient increasing distribution. S5. The melt after the devolatilization treatment in step S4 is subjected to underwater pelletizing, centrifugal drying and screening to obtain finished pellets.

2. The high-efficiency, low-energy granulation process for fully biodegradable multiphase composite materials according to claim 1, characterized in that, The raw materials, by weight, include: The polypropylene carbonate is 18 to 22 parts, the polybutylene adipate / terephthalate is 25 to 30 parts, the polylactic acid is 5 to 8 parts, the polyglycolic acid modified masterbatch is 20 to 25 parts, the plant fiber ultrafine powder is 8 to 12 parts, and the quaternary activated biomass hydroxyapatite is 3 to 5 parts. The additives include: 2 to 3 parts compatibilizer, 1 to 2 parts lubricant, 0.3 to 0.7 parts anti-hydrolysis agent, and 1 to 2 parts plasticizer.

3. The high-efficiency, low-energy granulation process for fully biodegradable multiphase composite materials according to claim 1, characterized in that, The preparation process of the fourth-level activated biomass hydroxyapatite includes: Biomass hydroxyapatite powder was subjected to fluidized bed radio frequency plasma etching under an oxygen atmosphere. The power was set to 200-400W and the treatment time was 5-15 minutes, resulting in a surface active site density of 5-8 sites / nm. 2 The first intermediate; The first intermediate was coated with stearic acid at a temperature of 80-95℃ for 1-3 hours to obtain a hydrophobically modified second intermediate with a contact angle of not less than 110 degrees. The second intermediate was grafted onto a silane coupling agent in an alcohol-water mixed solvent with a pH adjusted to 8.0-9.0 at a temperature of 60-80°C, yielding a grafting density of 1.5-2.5 molecules / nm. 2 A third intermediate for interface coupling modification; The third intermediate is melt-blended and crushed with polypropylene carbonate resin at 120-140°C to obtain the fourth-level activated biomass hydroxyapatite with a core-shell structure.

4. The high-efficiency, low-energy granulation process for fully biodegradable multiphase composite materials according to claim 1, characterized in that, In step S2: The melt temperature at the point where the plant fiber ultrafine powder is added is controlled between 145-155℃. The melt temperature at the location where the fourth-stage activated biomass hydroxyapatite is added is controlled between 155-160℃. The fourth-stage activated biomass hydroxyapatite undergoes only one thermal history in a temperature-controlled zone before entering the short-time reaction zone.

5. The high-efficiency, low-energy granulation process for fully biodegradable multiphase composite materials according to claim 1, characterized in that, The length-to-diameter ratio of the co-rotating parallel twin-screw extruder is not less than 64:1; The screw speed of the co-rotating parallel twin-screw extruder is controlled between 400-600 rpm, and the weighted average shear rate is controlled between 2000-4000 s. -1 ; The pressure field configuration of the co-rotating parallel twin-screw extruder is configured to maintain a melt pressure of 8-12 MPa in the short-time reaction zone; The fourth-stage activated biomass hydroxyapatite is subjected to high-shear treatment with a dispersion energy density of 2.5-3.5 kJ / kg after being added to the co-rotating parallel twin-screw extruder.

6. The high-efficiency, low-energy granulation process for fully biodegradable multiphase composite materials according to claim 1, characterized in that, The control strategy for the temperature field is as follows: The temperature of the enhanced melting zone is controlled between 130-160℃, and the temperature gradient is controlled at 25-30℃ per aspect ratio. The temperature of the short-time reaction zone is constantly controlled between 162-168℃, with fluctuations within ±1.5℃. The temperature in the rapid cooling zone is controlled between 158-125℃, and the cooling gradient is controlled at 40-45℃ per aspect ratio.

7. The high-efficiency, low-energy granulation process for fully biodegradable multiphase composite materials according to claim 1, characterized in that, In step S4: The vacuum level at the dynamic devolatilization port of the first stage is controlled at -0.090 to -0.095 MPa; The vacuum level at the dynamic devolatilization port of the second stage is controlled at -0.095 to -0.098 MPa; The vacuum level at the static devolatilization port is controlled between -0.092 and -0.096 MPa. The melt flow channel at the static devouring port adopts a porous flow divider structure to increase the exposed area of ​​the melt.

8. The high-efficiency, low-energy granulation process for fully biodegradable multiphase composite materials according to claim 1, characterized in that, The process also includes an online quality monitoring step, which uses a bypass rheological measurement module to measure the melt pressure drop and flow rate in real time through a standard capillary tube. The apparent shear viscosity of the melt is calculated in real time based on the melt pressure drop, the flow rate, and the geometric dimensions of the standard capillary. The calculated apparent shear viscosity is compared with the preset target viscosity range, and the temperature control system and screw speed of the co-rotating parallel twin-screw extruder are adjusted according to the comparison result.

9. The high-efficiency, low-energy granulation process for fully biodegradable multiphase composite materials according to claim 1, characterized in that, The process further includes an energy consumption closed-loop control step, which includes: A specific mechanical energy consumption prediction model is established, wherein the specific mechanical energy consumption prediction model is configured to obtain the specific mechanical energy consumption value by weighted summation of shear energy consumption component, pressure energy consumption component and time energy consumption component; Among them, the shear energy consumption component is determined based on the melt viscosity function and shear rate, the pressure energy consumption component is determined based on the pressure drop and total feed rate during the extrusion process, and the time energy consumption component is determined based on the material residence time. The specific mechanical energy consumption value is calculated in real time, and when the calculated specific mechanical energy consumption value deviates from the preset threshold, the heating power and motor frequency of each zone of the co-rotating parallel twin-screw extruder are adjusted.

10. A highly efficient and low-energy-consumption granulation system for fully biodegradable multiphase composite materials, characterized in that, The efficient and low-energy granulation process for the fully biodegradable multiphase composite material according to any one of claims 1-9 includes: The plant fiber pretreatment and ultrafine grinding unit integrates a hot air circulating dryer, a vertical turbine mill, a high-efficiency turbine classifier, and a powder surface modification module that includes an online low-temperature plasma treatment chamber and an atomized spray mixing chamber, arranged in series. A multi-channel precision feeding and gradient reaction devolatilization granulation unit includes a co-rotating parallel twin-screw extruder with an aspect ratio of not less than 64:1 and a feeding device. The barrel of the co-rotating parallel twin-screw extruder is provided with a main feed port, a first lateral feed port located at the front section of the barrel, a second lateral feed port located downstream of the first lateral feed port, and two-stage dynamic devolatilization and one-stage static devolatilization respectively connected to a vacuum pump group. The online quality inspection unit includes a bypass rheological measurement module connected to the front flow channel of the die head of the co-rotating parallel twin-screw extruder; The central intelligent control unit is bidirectionally connected to the multi-channel precision feeding and gradient reaction devolatilization granulation unit and the online quality detection unit. The central intelligent control unit is configured to calculate the apparent shear viscosity based on the data from the bypass rheological measurement module, compare the apparent shear viscosity with a preset target viscosity range, and adjust the temperature control system and screw speed of the co-rotating parallel twin-screw extruder based on the comparison result. The central intelligent control unit is also configured to calculate the specific mechanical energy consumption value using a specific mechanical energy consumption prediction model, and adjust the heating power and motor frequency of each zone of the co-rotating parallel twin-screw extruder when the specific mechanical energy consumption value deviates from a preset threshold.

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