A modified thermoplastic material and a method for its production

Abstract

The application discloses a modified thermoplastic material and a preparation method thereof, and specifically comprises the following steps: crushing corn raw materials to obtain corn starch, mixing the corn starch and water at a preset first mass ratio, and then performing shearing stirring to obtain a first mixture and a first water content of the first mixture; adjusting a second water content of natural organic acid, and adding the natural organic acid to perform acidification treatment to obtain a second mixture; wherein the second water content is used to make the pH value of the second mixture in a preset acidification interval and make the viscosity of the second mixture in a preset viscosity interval; after the second mixture is mixed with a bio-based polymer, ultrasonic treatment is performed to modify the second mixture to obtain a modified component; and thermoplastic raw materials and the modified component are mixed at a preset second mass ratio, and extrusion molding is performed to obtain the modified thermoplastic material. Through the above arrangement, the corn starch is acidified by using the natural organic acid, and the ultrasonic treatment is performed, so that the modified component is obtained to modify the plastic raw materials, and thus the performance and the degradability are improved.

Description

Technical Field

[0001] This invention relates to the field of plastics technology, and in particular to a modified thermoplastic material and its preparation method. Background Technology

[0002] Plastics, as one of the most widely used materials in modern society, have advantages such as light weight, good molding and processing properties, and low cost. Traditional plastics are usually petroleum-based, and their degradation rate is extremely slow. Long-term plastic waste has caused serious pollution to the ecological environment, especially the increasingly serious problem of marine plastic pollution. In order to alleviate this problem, those skilled in the art have begun to explore biodegradable plastics and alternative materials based on biomass resources.

[0003] In recent years, bio-based plastics have gradually gained attention as a potential green alternative. Although they have a lower carbon footprint and better biodegradability, effectively reducing the environmental burden of plastic products, their mechanical properties, thermal stability, and processability are often poor, limiting their application in the field of high-performance plastics. Therefore, improving the overall performance of bio-based plastics, especially in terms of mechanical properties, processing stability, and environmental friendliness, has become an important research direction in the field of plastic materials technology. At the same time, how to improve the degradability and recyclability of traditional plastics through more environmentally friendly means is also a technical problem that needs to be solved by those skilled in the art.

[0004] Therefore, it is necessary to develop a new modified thermoplastic material and its preparation method to improve the biodegradability and mechanical properties of plastics. Summary of the Invention

[0005] The purpose of this invention is to provide a new modified thermoplastic material and its preparation method, which solves the problems of poor biodegradability and insufficient mechanical properties of plastics in the prior art.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A method for preparing a modified thermoplastic material, comprising:

[0008] Step S100: The corn raw material is crushed to obtain corn starch. The corn starch and water are mixed in a preset first mass ratio and then sheared and stirred to obtain a first mixture and obtain the first water content of the first mixture.

[0009] Step S200: Adjust the second water content of the natural organic acid and add the natural organic acid for acidification treatment to obtain a second mixture; wherein, the second water content makes the pH value of the second mixture within a preset acidification range and the viscosity of the second mixture within a preset viscosity range.

[0010] Step S300: After mixing the second mixture with the bio-based polymer, the mixture is modified by ultrasonic treatment to obtain the modified component;

[0011] Step S400: Mix the thermoplastic raw material and the modified component according to a preset second mass ratio, and extrude to obtain the modified thermoplastic material;

[0012] The natural organic acid is one of citric acid, acetic acid, and succinic acid.

[0013] Optionally, step S100 specifically includes:

[0014] Step S110: Perform preliminary crushing treatment on the corn raw material to obtain corn particles with a particle size in the range of 300~500 micrometers;

[0015] Step S120: After mixing corn kernels and water at a preset first mass ratio, perform high-pressure shearing and stirring treatment at a temperature of 60~80℃ to dissolve part of the starch in the corn kernels. At the same time, adjust the stirring speed to 500~1000rpm to evenly disperse the corn starch and water to form the first mixture.

[0016] Step S130: The first mixture is pre-cooked at a temperature of 80~90℃ to further expand the starch granules. The pre-cooking time is 5~15 minutes.

[0017] Step S140: Rapidly cool the pre-cooked first mixture to 40~50°C to obtain the first mixture;

[0018] Step S150: Measure the water content of the first mixture.

[0019] Optionally, step S110 specifically includes:

[0020] Step S111: Perform preliminary screening on the corn raw materials to remove impurities and retain corn kernels with high integrity.

[0021] Step S112: The corn kernels are initially crushed using mechanical crushing equipment so that the particle size of the crushed corn kernels is in the range of 200~800 micrometers.

[0022] Step S113: Perform a second screening on the initially crushed corn kernels to remove particles with a diameter greater than 500 micrometers and separate fine powder with a diameter less than 300 micrometers to obtain corn kernels with a diameter in the range of 300 to 500 micrometers.

[0023] Step S114: Mix the screened corn kernels in a low-speed rotating mixer, and introduce low-flow-rate inert gas during the mixing process.

[0024] Optionally, step S140 specifically includes:

[0025] Step S141: The first mixture after pre-cooking treatment is quickly transferred to a cooling device, and the temperature of the first mixture is reduced to 40~50°C in stages by a pulse cooling system;

[0026] Step S142: During the cooling process, ultrasonic vibration is applied to the first mixture at a frequency of 20-50 kHz for a duration of 1-3 minutes.

[0027] Optionally, step S150 specifically includes:

[0028] Step S151: Insert a conductivity measuring sensor into the first mixture to measure the conductivity of the first mixture in real time and record the conductivity.

[0029] Step S152: Based on the calibration relationship curve between conductivity and water content, the measured conductivity value is converted into the water content of the first mixture to obtain the first water content of the first mixture.

[0030] Optionally, step S200 specifically includes:

[0031] S210. Calculate the mass of corn starch and the mass of the first water based on the mass of the first mixture and the first water content;

[0032] S220. Calculate the target mass of natural organic acids in the second mixture based on the mass of corn starch and the preset first matching formula; calculate the target mass of water in the second mixture based on the mass of corn starch and the preset second matching formula; and calculate the supplementary water mass based on the difference between the target water mass and the first water mass.

[0033] S230. Based on the target quality of natural organic acids and the quality of replenishing water, the second water content of natural organic acids is calculated.

[0034] S240, adjust the water content of natural organic acids to the second water content.

[0035] Optionally, step S300 includes:

[0036] Step S310: Mix the bio-based polymer with the second mixture at a preset third mass ratio to obtain the third mixture;

[0037] Step S320: Adjust the third mixture to 50~70℃, and subject the third mixture to ultrasonic treatment. The frequency of the ultrasonic wave is 20~40kHz, the power density is 30~50W / cm², and the duration is 5~10 minutes.

[0038] Optionally, before step S320, the method further includes:

[0039] Step S311: Add a dispersant to the third mixture and stir. The dispersant is nonylphenol polyoxyethylene ether with a mass fraction of 0.5% to 2.0%.

[0040] After step S320, the method further includes:

[0041] Step S321: Add 1% to 3% activated carbon adsorbent by mass to the third mixture, stir at 400 to 600 rpm for 3 to 5 minutes, and remove the activated carbon adsorbent by centrifugation.

[0042] Optionally, the bio-based polymer is one of polylactic acid, polyhydroxyalkanoate, and bio-based polyamide, and the thermoplastic raw material is thermoplastic polyester or polypropylene.

[0043] A modified thermoplastic material is obtained by the preparation method of the modified thermoplastic material as described above.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The modified thermoplastic material and its preparation method provided by this invention first involve crushing corn raw materials to obtain corn starch, then mixing the starch in a first mass ratio to obtain a first mixture. Natural organic acids are then added for acidification treatment, which not only breaks the hydrogen bonds in the starch molecules but also allows the starch to form active branches with high free energy in an acidic environment. This results in better reactivity of the starch molecules in subsequent mixing with bio-based polymers, and further, effective modification is achieved through ultrasonic treatment. Specifically, the dispersibility of the modified components is improved under the action of ultrasound, promoting cross-linking and bonding between different components, thereby improving the mechanical properties and processing stability of the material. In the above scheme, corn raw materials and natural organic acids are used directly, which has strong renewability. Furthermore, by adjusting the water content of the natural organic acids, the unpredictable moisture content after crushing the corn raw materials is overcome, ensuring that the viscosity of the second mixture is within a preset viscosity range. This prevents excessive moisture from causing excessive swelling of the corn starch and also prevents excessively high viscosity due to insufficient moisture, which would increase processing difficulty. This improves the performance and biodegradability of the modified thermoplastic material. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0048] Figure 1 This is a schematic flowchart illustrating the preparation method of the modified thermoplastic material provided in this embodiment. Detailed Implementation

[0049] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0050] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0051] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0052] Example 1:

[0053] This invention provides a method for preparing a modified thermoplastic material. By improving the preparation method, a modified thermoplastic material can be obtained. Compared with ordinary plastics, this modified thermoplastic material has higher biodegradability and performance, specifically in terms of mechanical properties, processing stability, and environmental friendliness.

[0054] like Figure 1 As shown, the method for preparing the modified thermoplastic material provided in this embodiment includes:

[0055] Step S100: The corn raw material is crushed to obtain corn starch. The corn starch and water are mixed at a preset first mass ratio and then subjected to high-pressure shearing and stirring to obtain a first mixture and obtain the first water content of the first mixture. As a renewable resource, corn raw material can effectively provide the structural basis of the raw material after crushing. Moreover, through mixing with water and shearing and stirring, it can create favorable conditions for subsequent modification processes. In this process, the corn starch and water are initially mixed at the first mass ratio to initially adjust the expansion and crystallization configuration of the starch particles.

[0056] Step S200: Adjust the second water content of the natural organic acid and add the natural organic acid for acidification treatment to obtain a second mixture; wherein, the second water content makes the pH value of the second mixture within a preset acidification range and the viscosity of the second mixture within a preset viscosity range.

[0057] Next, acidification is performed by adding natural organic acids, which enhances the activity of starch molecules. The acidification not only breaks the hydrogen bonds in the starch molecules but also allows the starch to form active branches with high free energy in an acidic environment. It should be noted that since the moisture content of the crushed corn raw material was not adjusted in step S100, the second water content of the natural organic acids needs to be precisely adjusted in step S200 to maintain the pH value of the second mixture within the preset acidification range and the viscosity of the second mixture within the preset viscosity range, thereby reducing the influence of moisture from the corn raw material. Furthermore, this step can save the drying time of the corn raw material, improve production efficiency, and overcome the defect that it is difficult to measure the moisture content of corn starch.

[0058] In step S300, the second mixture is mixed with the bio-based polymer and then subjected to ultrasonic treatment to obtain the modified component. Under the action of ultrasound, the internal structure of the material is optimized, the dispersibility of the modified component is improved, and the cross-linking and bonding between different components are promoted, thereby improving the mechanical properties and processing stability of the material.

[0059] Step S400: The thermoplastic raw material and the modified component are mixed according to a preset second mass ratio, which is approximately 1:(3~5). The modified thermoplastic material is obtained by extrusion molding under the process conditions of heating temperature of 180~190℃ and loading pressure of 12~14MPa.

[0060] It should be noted that after high pressure and acid treatment, the molecular structure of the modified components is more isotropic. This means that the modified material has a more uniform microstructure, which can not only improve the impact resistance, tensile strength, compressive strength and shear strength of the modified thermoplastic material, but also significantly improve the durability and applicability of the modified thermoplastic material.

[0061] The natural organic acid used is one of citric acid, acetic acid, or succinic acid. The selected natural organic acids, such as citric acid, acetic acid, or succinic acid, are all environmentally friendly and readily available chemicals. They not only effectively promote the modification reaction but also do not have adverse environmental impacts, meeting modern green and environmentally friendly requirements. This acidification treatment with natural organic acids not only improves the material's performance but also avoids the environmental burden caused by using other harmful chemical reagents.

[0062] In summary, the preparation method of the modified thermoplastic material in this embodiment first involves crushing corn raw materials to obtain corn starch, then mixing them according to a first mass ratio to obtain a first mixture, and then adding natural organic acids for acidification treatment. This not only breaks the hydrogen bonds in the starch molecules but also allows the starch to form active branches with high free energy in an acidic environment. This results in better reactivity of the starch molecules in subsequent mixing with bio-based polymers, and thus effective modification is achieved under ultrasonic treatment. Specifically, under the action of ultrasound, the dispersibility of the modified components is improved, promoting cross-linking and bonding between different components, thereby improving the mechanical properties and processing stability of the material. In the above scheme, corn raw materials and natural organic acids are used directly as raw materials, which has strong renewability. Furthermore, by adjusting the water content of the natural organic acids, the unpredictable moisture content after crushing corn raw materials is overcome, ensuring that the viscosity of the second mixture is within a preset viscosity range. This prevents excessive moisture from causing excessive swelling of the corn starch and also prevents excessively high viscosity due to insufficient moisture, which would increase processing difficulty. This improves the performance and biodegradability of the modified thermoplastic material.

[0063] Further, step S100 specifically includes:

[0064] Step S110: The corn raw material is initially crushed to obtain corn particles with a particle size in the range of 300-500 micrometers. It should be understood that if the particle size of the corn particles is too large, the starch will not dissolve sufficiently, and if the particle size is too small, it will easily cause agglomeration. Filtering to obtain corn particles with a particle size in the range of 300-500 micrometers can ensure that the corn particles can be fully dissolved and maintain uniform dispersion during the shearing, stirring and pre-cooking process.

[0065] Step S120: After mixing corn kernels and water at a preset first mass ratio, perform high-pressure shearing and stirring treatment at a temperature of 60~80℃ to dissolve some of the corn starch in the corn kernels. At the same time, adjust the stirring speed to 500~1000rpm to evenly disperse the corn starch and water to form a first mixture. In this embodiment, the first mass ratio is preferably 1:4. In other optional embodiments, it can be 1:(3.5~4.5).

[0066] It should be noted that the high-pressure shearing and stirring treatment is achieved through a high-pressure shearing and stirring device, which mainly consists of a high-pressure reactor, a stirring system, and a heating system. The above structure is well known to those skilled in the art and will not be elaborated in detail in this embodiment. The high-pressure reactor can withstand high internal pressure (e.g., 1~5MPa), and the stirring system can achieve high-speed shearing (500~1000rpm), which can effectively disperse materials and promote the dissolution of corn starch.

[0067] Step S130: The first mixture is pre-cooked at a temperature of 80-90℃ to further expand the granular structure of the corn starch and partially destroy its crystal structure, forming a first mixture with preliminary rheological properties. The pre-cooking time is 5-15 minutes. In this step, the granular structure of the corn starch in the first mixture is further expanded and its crystal structure is partially destroyed, thereby forming a first mixture with preliminary rheological properties. Within this temperature range, the crystalline regions of the granular structure are destroyed, and the internal hydrogen bonds are partially broken, forming a molecular structure with higher reactivity. The controlled pre-cooking time ensures that the granular structure of the corn starch is neither insufficiently expanded due to too short a time nor over-gelatinized due to too long a time, thus affecting its subsequent interaction with natural organic acids and bio-based polymers.

[0068] It should be noted that the pre-cooking process is achieved through pre-cooking equipment, which is either a heating tank or a continuous pre-cooking machine, and is equipped with a stirring device to ensure that the material is heated evenly.

[0069] Step S140: The pre-cooked first mixture is rapidly cooled to 40-50°C to obtain the first mixture. This cooling process stabilizes the adjusted molecular structure of the corn starch and prevents starch degradation or viscosity changes caused by spontaneous reactions at high temperatures. Simultaneously, this cooling temperature range provides suitable environmental conditions for subsequent water content measurement, avoiding measurement errors caused by excessively high temperatures.

[0070] Step S150: Measure the water content of the first mixture.

[0071] More specifically, step S110 includes:

[0072] Step S111: Perform preliminary screening of corn raw materials to remove impurities and retain corn raw materials with higher integrity. This process can effectively eliminate foreign impurities such as sand and straw in corn raw materials, while ensuring the consistency of the selected corn raw materials in terms of physical properties and chemical composition, which helps to improve the processing stability and reaction efficiency of particles in subsequent processing.

[0073] Step S112: The corn raw material is initially crushed using mechanical crushing equipment, resulting in corn kernels with a particle size range of 200-800 micrometers. During this process, the corn raw material is crushed into corn kernels containing corn starch. Excessively large particle sizes reduce screening efficiency and hinder the uniform dissolution of starch in subsequent processing; excessively small particle sizes easily cause agglomeration, increasing the difficulty of dispersion and mixing. By appropriately adjusting the blade gap and rotation speed of the crushing equipment, uniformly crushed corn kernels can be obtained, significantly improving the consistency of the raw material.

[0074] Step S113: The initially crushed corn kernels are screened a second time to remove particles with a diameter greater than 500 micrometers and separate fine powder with a diameter less than 300 micrometers to obtain corn kernels with a diameter in the range of 300 to 500 micrometers. The above settings can prevent the performance of the kernels from declining due to oxidation during the mixing process.

[0075] Step S114: The screened corn kernels are mixed in a low-speed rotating mixer. During the mixing process, a low-flow-rate inert gas is introduced to obtain a viscous corn kernel mixture. The introduction of inert gas effectively isolates the kernels from oxygen and moisture in the air. At the same time, the low-speed rotating mixer ensures that the kernels achieve a highly uniform mixing state without being damaged by excessive mechanical force. This process not only improves the storage stability of the corn kernels but also makes their performance more stable in subsequent processing.

[0076] It is important to note that, considering the need to adjust the second water content of the natural organic acids in subsequent steps, pre-drying is unnecessary in the above steps. The resulting corn kernels can be viscous or pasty, thus improving the processing efficiency of the corn raw material. This not only simplifies the process but also effectively avoids the risks of increased energy consumption and altered raw material properties caused by unnecessary drying steps. This allows the corn kernels to better maintain their structural integrity during initial crushing and mixing, preventing brittleness or excessive pulverization due to moisture loss. Furthermore, since subsequent steps precisely control the viscosity and equilibrium of the system by adjusting the second water content of the natural organic acids, the undried corn raw material can better form a uniformly distributed mixture with the natural organic acids, providing ideal initial conditions for the acidification reaction. This avoids the problems of incomplete starch granule swelling or poor dispersibility caused by insufficient moisture, while also preventing decreased acidification reaction efficiency or viscosity instability caused by excessive moisture.

[0077] In addition, the aforementioned mechanical crushing equipment includes, but is not limited to, hammer mills, toothed roller mills, or ball mills; the aforementioned screening equipment includes, but is not limited to, vibrating screens, cyclone screens, and centrifugal screens, the difference between each screening being that the mesh size of the screen varies; the mixer includes, but is not limited to, V-type mixers, double cone mixers, or spiral belt mixers, mainly used for mixing corn kernels.

[0078] More specifically, step S140 includes:

[0079] Step S141: The first mixture after pre-cooking treatment is quickly transferred to a cooling device, and the temperature of the first mixture is reduced to 40~50°C in stages by a pulse cooling system. The pulse cooling system is an indirect refrigeration device that can intermittently introduce cooling medium, which is well known to those skilled in the art and will not be described in detail in this embodiment.

[0080] Step S142: During the cooling process, ultrasonic vibration is applied to the first mixture at a frequency of 20-50 kHz for a duration of 1-3 minutes.

[0081] Understandably, the pulse cooling system, by reducing the temperature in stages, avoids the uneven temperature gradient and particle agglomeration caused by rapid cooling in traditional cooling methods. Simultaneously, it ensures that the first mixture maintains stable viscosity and rheological properties as it cools from a high temperature to 40-50°C. The introduction of ultrasonic vibration further enhances the particle dispersion effect during cooling. Its 20-50kHz high-frequency vibration, through cavitation and microflow effects, disrupts the weak aggregation forces between particles, resulting in a more uniform dispersion of the first mixture and thus improving the consistency and stability of its internal structure. Through these measures, the stability and efficiency of the cooling process are improved, and a higher-quality raw material base is provided for subsequent acidification and modification operations, significantly improving the mechanical properties and production consistency of the modified thermoplastic material.

[0082] More specifically, step S150 includes:

[0083] Step S151: Insert a conductivity measuring sensor into the first mixture to measure the conductivity of the first mixture in real time and record the conductivity value.

[0084] Step S152: Based on the calibration relationship curve between conductivity and water content, the measured conductivity value is converted into the water content of the first mixture to obtain the first water content of the first mixture.

[0085] Understandably, changes in water content significantly affect the overall conductivity of a mixture. Specifically, conductivity increases with increasing water content and vice versa. Therefore, by measuring conductivity and using a pre-calibrated conductivity-water content relationship curve, the water content of the mixture can be calculated more accurately and efficiently, avoiding errors caused by cumbersome operations or measurement lags in traditional methods. It should be noted that the calibration curve for conductivity versus water content can be obtained experimentally. Specifically, a series of standard samples with known water content can be prepared, and their conductivity values ​​can be measured under controlled water content ranges (e.g., 10%–35%) and constant temperature conditions. By plotting a scatter plot of conductivity versus water content and performing curve fitting, a mathematical model of the relationship between the two can be established, thus obtaining the calibration curve for conductivity versus water content.

[0086] Further, step S200 specifically includes:

[0087] S210. Based on the mass M1 of the first mixture and the first water content C1, calculate the mass of corn starch and the mass of the first water.

[0088] Specifically, the mass of corn starch M11 = M1 × (1 - C1); the mass of the first water M12 = M1 × C1;

[0089] S220. Based on the mass M11 of corn starch and the preset first matching formula, calculate the target mass M21 of natural organic acid in the second mixture; based on the mass M11 of corn starch and the preset second matching formula, calculate the target mass M13 of water in the second mixture; and based on the difference between the target mass M13 and the first mass M12, calculate the supplementary water mass M22.

[0090] The first and second matching equations can be obtained through prior experiments. They reflect the required amounts of natural organic acid and water for different corn starch masses to bring the pH of the second mixture into a preset acidification range and the viscosity into a preset viscosity range. For reference, the preset acidification range is 3.0–5.0, and the preset viscosity range is 1000 mPa·s–3000 mPa·s. For example, the first and second matching equations can be determined using a sample method. Multiple sets of corn starch samples of different masses are prepared. For the same corn starch mass, each set of samples corresponds to multiple different pH values ​​and viscosities, corresponding to the required amounts of water and natural organic acid. The acidified corn starch is then subjected to subsequent processing steps to select the optimal modified thermoplastic material, thereby determining the required amounts of water and natural organic acid for that corn starch mass. By repeatedly performing the above sample method on multiple sets of corn starch samples of different masses, the corresponding amounts of water and natural organic acid for different masses of corn starch can be determined, i.e., the corresponding pH and viscosity ranges, thus determining the first and second matching equations. By identifying the optimal pH and viscosity ranges—specifically, the ranges determined by analyzing the modified thermoplastic material prepared from the sample—we can pinpoint the pH and viscosity ranges within which a given mass of corn starch sample would yield the best performance of the modified thermoplastic material. This allows us to determine the required concentration of natural organic acids to be added to the corn starch sample. Consequently, we can determine the required amount of water and natural organic acids for different masses of corn starch, facilitating the rapid determination of the necessary water replenishment for natural organic acids.

[0091] S230. Based on the target mass of natural organic acid M21 and the mass of replenishing water M22, the second water content C2 of natural organic acid is calculated; the second water content C2 = M22 / (M21 + M22).

[0092] S240, Adjust the water content of the initial natural organic acid to the second water content C2.

[0093] The core of the above steps lies in providing the conditions required for acidification of the second mixture with different masses and different water contents through fitting methods familiar to those skilled in the art, such as the sample method and the table lookup method. This allows those skilled in the art to adjust the concentration or ratio of natural organic acids, thereby preventing the pH value and viscosity from failing to meet the standards during subsequent processing, and thus avoiding the decline in the performance of the modified thermoplastic material.

[0094] Further, step S300 includes:

[0095] Step S310: Mix the bio-based polymer with the second mixture at a preset third mass ratio to obtain the third mixture; wherein, the third mass ratio is 1:(4~6), and in this embodiment, it is preferably 1:5;

[0096] Step S320: Adjust the third mixture to 50~70℃, and subject the third mixture to ultrasonic treatment. The frequency of the ultrasonic wave is 20~40kHz, the power density is 30~50W / cm², and the duration is 5~10 minutes.

[0097] Specifically, temperature control of 50–70°C significantly reduces the viscosity of the third mixture, resulting in more uniform dispersion of the bio-based polymer in the second mixture. Under this appropriate heating environment, the fluidity of the corn starch molecular chains increases, while the interfacial interaction between the natural organic acid molecules and the bio-based polymer is further strengthened, providing an ideal dispersion basis for ultrasonic treatment. Secondly, the 50–70°C temperature range falls within the partial softening range of the bio-based polymer, while remaining below the thermal degradation temperature of corn starch and natural organic acids. Within this temperature range, the molecular chains of the bio-based polymer begin to extend without breaking down due to excessively high temperatures or causing side reactions. In other words, the expansion of corn starch is also controlled within a reasonable range, increasing the interaction area with the bio-based polymer while avoiding structural instability caused by excessive expansion. This allows for optimization of the material structure at the molecular scale, providing a stable foundation for subsequent modification.

[0098] Furthermore, prior to step S320, the following steps are also included:

[0099] Step S311: Add a dispersant to the third mixture and stir. The dispersant is nonylphenol polyoxyethylene ether with a mass fraction of 0.5% to 2.0%. The ratio of the dispersant to the third mixture is approximately 1: (50 to 60).

[0100] After step S320, the method further includes:

[0101] Step S321: Add 1% to 3% activated carbon adsorbent by mass to the third mixture, stir at 400 to 600 rpm for 3 to 5 minutes, and remove the activated carbon adsorbent by centrifugation.

[0102] It should be noted that the dispersant can significantly reduce the interfacial tension between the bio-based polymer and the second mixture, improve the dispersion state of the two-phase system, make ultrasonic treatment more efficient, and achieve more uniform molecular chain breakage and recombination, ultimately improving the mechanical properties and stability of the modified component. Removing the dispersant in step S321 can reduce the environmental problems caused by the dispersant.

[0103] The bio-based polymer is one of polylactic acid, polyhydroxyalkanoate, or bio-based polyamide, and the thermoplastic raw material is thermoplastic polyester or polypropylene. For example: 1. Polylactic acid (PLA) is selected as the bio-based polymer, and thermoplastic polyester is selected as the thermoplastic raw material; in step S300, polylactic acid and the second mixture are fully mixed under ultrasonic action to form a uniform modified component, promoting intermolecular cross-linking and bonding; under the high temperature and high pressure conditions of step S400, the modified component and thermoplastic polyester are further melt-blended to form a modified thermoplastic material with excellent mechanical properties, suitable for applications requiring high strength and environmental friendliness; 2. Polyhydroxyalkanoate (pHA) is selected as the bio-based polymer, and polypropylene is selected as the thermoplastic raw material. After acidification and ultrasonic modification, the molecular chains of polyhydroxyalkanoate form a closer interaction in the modified component; The addition of propylene improves the melt flow index and processing performance of the material, giving the modified thermoplastic material good toughness, heat resistance, and biodegradability, making it suitable for films, packaging materials, and other fields. 3. The bio-based polymer is bio-based polyamide, and the thermoplastic raw material is thermoplastic polyester. In step S300, the bio-based polyamide and the second mixture undergo effective interfacial fusion under ultrasonic action, forming a uniformly structured modified component. During the subsequent extrusion molding process, the microstructure of the material is optimized, exhibiting isotropic characteristics. This combination gives the modified thermoplastic material excellent tensile strength, impact resistance, and abrasion resistance, making it suitable for high-performance engineering plastic applications, such as automotive parts and electronic device housings. The above settings indicate that the combination of the modified component and thermoplastic raw material in this embodiment provides optional solutions for different types of application scenarios.

[0104] Example 2:

[0105] This embodiment also provides a modified thermoplastic material, which is prepared by the preparation method in Example 1.

[0106] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a modified thermoplastic material, characterized in that, include: Step S100: The corn raw material is crushed to obtain corn starch. The undried corn starch and water are mixed in a preset first mass ratio and then sheared and stirred to obtain a first mixture and obtain the first water content of the first mixture. Step S200: Adjust the second water content of the natural organic acid and add the natural organic acid for acidification treatment to obtain a second mixture; wherein, the second water content makes the pH value of the second mixture within a preset acidification range and the viscosity of the second mixture within a preset viscosity range. Step S310: Mix the bio-based polymer with the second mixture at a preset third mass ratio to obtain the third mixture; Step S320: Adjust the third mixture to 50~70℃, and subject the third mixture to ultrasonic treatment to obtain the modified component; the frequency of the ultrasonic wave is 20~40kHz, the power density is 30~50W / cm², and the duration is 5~10 minutes. Step S400: Mix the thermoplastic raw material and the modified component according to a preset second mass ratio, and extrude to obtain the modified thermoplastic material; The natural organic acid is one of citric acid, acetic acid, and succinic acid.

2. The method for preparing a modified thermoplastic material according to claim 1, characterized in that, Step S100 specifically includes: Step S110: Perform preliminary crushing treatment on the corn raw material to obtain corn particles with a particle size in the range of 300~500 micrometers; Step S120: After mixing corn kernels and water at a preset first mass ratio, perform high-pressure shearing and stirring treatment at a temperature of 60~80℃ to dissolve part of the starch in the corn kernels. At the same time, adjust the stirring speed to 500~1000rpm to evenly disperse the corn starch and water to form the first mixture. Step S130: The first mixture is pre-cooked at a temperature of 80~90℃ to further expand the starch granules. The pre-cooking time is 5~15 minutes. Step S140: Rapidly cool the pre-cooked first mixture to 40~50°C to obtain the first mixture; Step S150: Measure the water content of the first mixture.

3. The method for preparing a modified thermoplastic material according to claim 2, characterized in that, Step S110 specifically includes: Step S111: Perform preliminary screening on the corn raw materials to remove impurities and retain corn raw materials with higher integrity. Step S112: The corn raw material is initially crushed by mechanical crushing equipment so that the particle size of the crushed corn particles is in the range of 200~800 micrometers. Step S113: Perform a second screening on the initially crushed corn kernels to remove particles with a diameter greater than 500 micrometers and separate fine powder with a diameter less than 300 micrometers to obtain corn kernels with a diameter in the range of 300 to 500 micrometers. Step S114: Mix the screened corn kernels in a low-speed rotating mixer, and introduce low-flow-rate inert gas during the mixing process.

4. The method for preparing a modified thermoplastic material according to claim 2, characterized in that, Step S140 specifically includes: Step S141: The first mixture after pre-cooking treatment is quickly transferred to a cooling device, and the temperature of the first mixture is reduced to 40~50°C in stages by a pulse cooling system; Step S142: During the cooling process, ultrasonic vibration is applied to the first mixture at a frequency of 20-50 kHz for a duration of 1-3 minutes.

5. The method for preparing a modified thermoplastic material according to claim 2, characterized in that, Step S150 specifically includes: Step S151: Insert a conductivity measuring sensor into the first mixture to measure the conductivity of the first mixture in real time and record the conductivity. Step S152: Based on the calibration relationship curve between conductivity and water content, the measured conductivity value is converted into the water content of the first mixture to obtain the first water content of the first mixture.

6. The method for preparing a modified thermoplastic material according to claim 2, characterized in that, Step S200 specifically includes: S210. Calculate the mass of corn starch and the mass of the first water based on the mass of the first mixture and the first water content; S220. Calculate the target mass of natural organic acids in the second mixture based on the mass of corn starch and the preset first matching formula; calculate the target mass of water in the second mixture based on the mass of corn starch and the preset second matching formula; and calculate the supplementary water mass based on the difference between the target water mass and the first water mass. S230. Based on the target quality of natural organic acids and the quality of replenishing water, the second water content of natural organic acids is calculated. S240, adjust the water content of natural organic acids to the second water content.

7. The method for preparing a modified thermoplastic material according to claim 1, characterized in that, Before step S320, the method further includes: Step S311: Add a dispersant to the third mixture and stir. The dispersant is nonylphenol polyoxyethylene ether with a mass fraction of 0.5% to 2.0%. After step S320, the method further includes: Step S321: Add 1% to 3% activated carbon adsorbent by mass to the third mixture, stir at 400 to 600 rpm for 3 to 5 minutes, and remove the activated carbon adsorbent by centrifugation.

8. The method for preparing a modified thermoplastic material according to claim 1, characterized in that, The bio-based polymer is one of polylactic acid, polyhydroxyalkanoate, and bio-based polyamide, and the thermoplastic raw material is thermoplastic polyester or polypropylene.

9. A modified thermoplastic material, characterized in that, It is obtained by the preparation method of the modified thermoplastic material as described in any one of claims 1 to 8.

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