A modified plastic processing method and device based on dynamic threshold control and medium

Abstract

The application discloses a modified plastic processing method and device based on dynamic threshold control and a medium, and the method comprises the following steps: testing the mass change of a target additive at several constant temperatures to obtain thermal degradation characteristic parameters of the target additive, combining related parameters of a double-screw extruder to calculate the cumulative degradation rate from a feeding port to a die port; according to the cumulative degradation rate, iteratively updating the farthest feeding point until the actual service life of a modified plastic corresponding tensile test sample strip is greater than or equal to a target value, and outputting the final farthest feeding point of the double-screw extruder. The application provides a modified plastic processing method and device based on dynamic threshold control and a medium, the cumulative degradation rate is calculated, the performance feedback is combined to dynamically optimize the side feeding position, the experience setting is converted into data-based regulation and control, the additive degradation loss is reduced, the utilization rate is improved, and the problem that the prior art relies on experience rules to set the side feeding position of the double-screw extruder and is difficult to improve the utilization rate of the additive can be solved.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing technology, and in particular to a modified plastic processing method, apparatus and medium based on dynamic threshold control. Background Technology

[0002] Modified plastics are key basic materials in modern industry, playing a vital role in high-end fields such as automobile manufacturing, electronic equipment, and precision packaging. Their performance enhancement primarily relies on functional additives: antioxidants (such as Irganox 1010) inhibit thermo-oxidative degradation, significantly extending the service life of car bumpers at high temperatures; anti-hydrolysis stabilizers react with carboxyl and hydroxyl groups generated by unstable reactions of polymers under the influence of heat, light, and humidity, blocking the autocatalytic attack cycle of these groups on the polymer backbone and improving the material's thermo-oxidative aging stability; light stabilizers (such as Tinuvin 770) block photo-oxidation reactions, solving the problems of yellowing and performance degradation in outdoor applications. Furthermore, some light stabilizers can react with free radicals, preventing the expansion of oxidation chain reactions and indirectly improving the material's thermal stability; flame retardants enhance the material's flame retardant performance to UL94V-0 through a dual mechanism, influencing the material's thermal decomposition behavior and thermo-oxidative stability; toughening agents improve the material's microstructure while absorbing and dispersing impact energy, enhancing the material's aging resistance. These additives construct a protective system at the molecular level, achieving breakthroughs in material durability and safety. For twin-screw extrusion processes used in the production of modified plastics, side-feed technology is suitable for the physical dispersion of materials such as glass fiber and mineral fillers, with the core objective of avoiding high-shear damage in the molten section; while the addition process of functional additives is still mainly based on main feeding, that is, adding them simultaneously with the matrix resin from the feed port.

[0003] However, in current twin-screw extrusion processes, the main-feeding method for adding functional additives requires heat-sensitive additives to undergo high-temperature melting zones and high-shear fields throughout the process, making their molecular chains susceptible to damage. For example, halogenated flame retardants suffer significant loss of active ingredients due to thermal degradation, requiring excessive addition to maintain performance, which can easily lead to precipitation, yellowing, and other problems. While side-feeding processes can theoretically shorten the thermal exposure time of additives and reduce degradation risks, two major obstacles exist in their implementation: first, the selection of the side-feeding location relies on empirical rules, failing to establish a dynamic correlation between the thermal aging life of additives and processing parameters; second, static threshold control lacks scientific basis, failing to quantify the relationship between additive degradation rates and product lifespan during processing, merely constraining processing losses without anchoring product performance, essentially remaining based on empirical rules and lacking a "performance-oriented" scientific approach. Summary of the Invention

[0004] This invention provides a modified plastics processing method, apparatus, and medium based on dynamic threshold control, to solve the problem that existing technologies rely on empirical rules to set the side feeding position of twin-screw extruders, making it difficult to improve the utilization rate of additives.

[0005] To achieve the above objectives, the present invention provides a modified plastic processing method based on dynamic threshold control, comprising: The mass change of the target additive at several constant temperatures was tested to obtain the thermal degradation characteristic parameters of the target additive; Based on the set temperature of each temperature zone in the twin-screw extruder, the material residence time, and the thermal degradation characteristic parameters, the cumulative degradation rate of the target additive from the feed port to the die port is calculated. Based on the cumulative degradation rate, the farthest side-feeding point of the safe side-feeding interval is iteratively updated until the actual lifespan of the tensile test specimen of the modified plastic is greater than or equal to the target value, and the final farthest side-feeding point of the target additive in the twin-screw extruder is output; wherein, the farthest side-feeding point is the position where the cumulative degradation rate is less than or equal to the first threshold; in each iteration, based on the target additive, tensile test specimens are produced according to the farthest side-feeding point of the current iteration, and the tensile performance retention rate and actual lifespan of the tensile test specimen of the current iteration are obtained after the tensile test specimen undergoes a preset aging test; in each iteration, the first threshold is updated according to a preset mechanism.

[0006] This invention obtains specific thermal degradation characteristic parameters by testing the mass change of target additives at different constant temperatures, providing quantifiable basic data for subsequent analysis. This replaces the vague judgment of additive heat resistance based on traditional experience and avoids positioning deviations caused by differences in additive types. By combining the temperatures of each temperature zone of the twin-screw extruder, the material residence time, and the aforementioned thermal degradation parameters, the cumulative degradation rate of the additive from the feed port to the die is quantitatively calculated. This transforms the selection of the side feeding position from experience-based judgment to data-driven scientific analysis, accurately identifying the range with the lowest degree of additive degradation. The farthest side feeding point is determined based on the standard that the cumulative degradation rate of the additive is less than or equal to a first threshold. Using a clear numerical standard to replace empirical range delineation, this ensures that the side feeding position is within a safe range where additive degradation is controllable, reducing additive loss due to excessive degradation. The performance of the sample is verified through aging experiments. If the performance does not meet the standard, the threshold is lowered and the side feeding point is redefined, forming an effective closed-loop adjustment. This dynamic optimization ensures that the side feeding position can both reduce additive degradation and meet the final performance requirements of the product, avoiding the problem of static experience rules being out of sync with actual performance, ultimately achieving an effective improvement in additive utilization.

[0007] Compared to existing technologies, this invention tests the thermal degradation characteristics of additives, calculates the cumulative degradation rate, and dynamically optimizes the side-feed position based on performance feedback. This transforms empirical settings into data-driven control, reducing additive degradation losses and improving utilization. Therefore, it solves the problem that existing technologies rely on empirical rules to set the side-feed position of twin-screw extruders, making it difficult to improve additive utilization.

[0008] As a preferred approach, the mass change of the target additive is tested at several constant temperatures to obtain the thermal degradation characteristic parameters of the target additive, specifically including: The mass change of the target adjuvant at several constant temperatures was tested to obtain the weight loss curves relating reaction temperature, time, and degradation rate. The degradation time corresponding to different temperatures at the target degradation rate is obtained based on the weight loss curve. The degradation reaction rate at different temperatures is calculated based on the target degradation rate and the corresponding degradation time to obtain several degradation reaction rates. Based on the Arrhenius equation, linear regression was performed on the natural logarithm set of the degradation reaction rates and the reciprocal of the Kelvin temperature to obtain the thermal degradation characteristic parameters of the target adjuvant.

[0009] This preferred scheme obtains weight loss curves by testing the mass change of the additive at multiple constant temperatures, which can systematically reflect the correlation between reaction temperature, time and degradation rate, providing an objective experimental basis for subsequent analysis. Based on the weight loss curves, the degradation reaction rate at different temperatures is calculated, and then the thermal degradation characteristic parameters are obtained by combining linear regression with the Arrhenius equation, realizing quantitative modeling of the thermal degradation law of the additive, avoiding the error of empirical judgment, and improving the scientific nature of the parameters. At the same time, this scheme establishes a dynamic correlation between the thermal aging characteristics of the additive and temperature, solving the problems in the prior art where the selection of the side feeding position depends on empirical rules and the lack of a dynamic correlation between the thermal aging life of the additive and processing parameters.

[0010] As a preferred embodiment, based on the cumulative degradation rate, the furthest side-feeding point of the safe side-feeding interval is iteratively updated until the actual lifespan of the tensile test specimen of the modified plastic is greater than or equal to the target value. The final furthest side-feeding point of the target additive in the twin-screw extruder is then output, specifically including: During each iteration, the position where the cumulative degradation rate is less than or equal to the first threshold is defined as the farthest side-feeding point of the safe side-feeding interval; The tensile test specimen is produced based on the farthest feeding point, and the initial tensile strength of the tensile test specimen in the initial state is obtained. The tensile test specimen is subjected to the preset aging test. The tensile strength of the tensile test specimen is taken at several intermediate time points and at the end of the test. The tensile performance retention rate of the tensile test specimen is calculated based on the initial tensile strength and the tensile strength. The tensile performance retention rate set corresponding to the several intermediate time points and the final tensile performance retention rate corresponding to the end of the test are obtained respectively. Based on the set of tensile performance retention rates and the final tensile performance retention rate, a dynamic model of performance decay is fitted according to a polynomial equation, and the actual life corresponding to the tensile performance retention rate of the tensile test specimen is calculated according to the dynamic model. If the final tensile performance retention rate is less than the target performance retention rate, or the actual lifespan is shorter than the target lifespan, then the first threshold is updated according to the preset mechanism and the next iteration is entered to obtain the second preset threshold, until the final tensile performance retention rate of the tensile test specimen is greater than or equal to the target performance retention rate, or the actual lifespan is longer than or equal to the target lifespan, and the final farthest feeding point of the target additive in the twin-screw extruder is output.

[0011] This preferred solution comprehensively captures the dynamic trend of performance degradation by obtaining the initial tensile strength and the tensile performance retention rate at multiple intermediate time points and the end of the experiment, avoiding the limitations of data from a single time point. By combining polynomial equation fitting of the dynamic model and calculating the actual life, short-term experimental data is correlated with long-term performance prediction, so that the threshold adjustment is not only based on the measured results, but also incorporates scientific life prediction, enhancing the scientific nature of the decision. At the same time, using the final tensile performance retention rate being less than the preset threshold or the actual life being less than the target life as the judgment condition can comprehensively cover the situation of substandard performance, ensuring the timeliness and accuracy of threshold adjustment.

[0012] As a preferred embodiment, after obtaining the set of tensile property retention rates corresponding to the plurality of intermediate time points, the method further includes: If any tensile performance retention rate in the set of tensile performance retention rates is less than the target performance retention rate, the preset aging experiment ends at the corresponding intermediate time point, and the first threshold is updated according to the preset mechanism.

[0013] This preferred solution monitors the tensile performance retention rate at intermediate time points. If any intermediate value falls below the target performance retention rate, the aging experiment can be terminated early and threshold adjustment can be triggered, avoiding the waste of time and resources caused by waiting until the end of the experiment, and significantly improving the efficiency of process optimization. At the same time, this dynamic response mechanism based on intermediate data can detect the problem of premature performance degradation earlier, making threshold adjustment more timely.

[0014] As a preferred embodiment, in each iteration, based on the target additive, tensile test specimens are produced according to the farthest feeding point of the current iteration, specifically including: During each iteration, in the twin-screw extruder, the target additive is added to the first region corresponding to the farthest feed point of the current iteration, so that the target additive sequentially experiences each temperature zone from the first region to the die orifice; Modified plastics are produced using the configured twin-screw extruder to obtain plastic samples; The plastic sample is injection molded to obtain the tensile test strip that meets the preset test standards.

[0015] This preferred solution, by adding the target additive to the first region corresponding to the farthest feeding point, ensures that the additive only sequentially experiences each temperature zone from this region to the die opening. This allows for strict control of the additive's heat exposure time and intensity during processing, minimizing additive degradation caused by high temperature and high shear, and ensuring the effective utilization rate of the additive in the modified plastic. Based on this, the plastic samples produced and the tensile test strips obtained through injection molding can truly reflect the effect of the target additive under reasonable processing conditions, providing reliable sample support for the accuracy of performance data and the scientific nature of threshold optimization in subsequent aging experiments.

[0016] As a preferred embodiment, updating the first threshold according to a preset mechanism specifically includes: The actual attenuation rate of the tensile test specimen is calculated based on the actual lifespan and the preset theoretical lifespan. The actual attenuation rate is then used as an adjustment coefficient to reduce the first threshold of the additive degradation rate, resulting in an updated first threshold.

[0017] This preferred solution uses the actual attenuation rate as the adjustment coefficient, which can accurately reflect the impact of the processing technology on product performance, ensure that the correction of the first threshold is directly linked to the product's service performance requirements, form a closed-loop optimization from processing to service, and improve the reliability and iteration efficiency of process control.

[0018] As a preferred embodiment, the feed port is the initial inlet for the material to enter the twin-screw extruder, located at the beginning of the twin-screw extruder. After entering through the feed port, the material flows sequentially through each temperature zone and moves toward the die orifice. The die orifice is the final outlet for the material to be extruded and formed, located at the end of the twin-screw extruder.

[0019] This preferred solution clarifies the material flow path in the twin-screw extruder. By defining the positions of the feed inlet and the die, the sequence of each temperature zone and the material residence time can be accurately divided, ensuring that the cumulative degradation rate from the feed inlet to the die can be accurately calculated. This lays the foundation for scientifically determining the safe side-feeding zone and avoids process parameter calculation errors caused by ambiguous position definitions.

[0020] The present invention also provides a modified plastics processing apparatus based on dynamic threshold control, including a data module, a degradation module and an optimization module; The data module is used to test the mass change of the target additive at several constant temperatures to obtain the thermal degradation characteristic parameters of the target additive. The degradation module is used to calculate the cumulative degradation rate of the target additive from the feed inlet to the die orifice based on the set temperature of each temperature zone in the twin-screw extruder, the material residence time, and the thermal degradation characteristic parameters. The optimization module is used to iteratively update the farthest side-feeding point of the safe side-feeding interval according to the cumulative degradation rate, until the actual life of the tensile test specimen of the modified plastic is greater than or equal to the target value, and output the final farthest side-feeding point of the target additive in the twin-screw extruder; wherein, the farthest side-feeding point is the position where the cumulative degradation rate is less than or equal to a first threshold; in each iteration, based on the target additive, tensile test specimens are produced according to the farthest side-feeding point of the current iteration, and the tensile performance retention rate and actual life of the tensile test specimens of the current iteration are obtained after the tensile test specimens undergo a preset aging test; in each iteration, the first threshold is updated according to a preset mechanism.

[0021] As a preferred embodiment, the data module includes a curve unit, a degradation unit, and a parameter unit; The curve unit is used to test the mass change of the target adjuvant at several constant temperatures to obtain a weight loss curve showing the relationship between reaction temperature, time, and degradation rate. The degradation unit is used to obtain the degradation time corresponding to different temperatures at the target degradation rate based on the weight loss curve, and to calculate the degradation reaction rate at different temperatures based on the target degradation rate and the corresponding degradation time, thereby obtaining several degradation reaction rates. The parameter unit is used to perform linear regression on the set of natural logarithms of the several degradation reaction rates and the reciprocal of the Kelvin temperature based on the Arrhenius equation to obtain the thermal degradation characteristic parameters of the target adjuvant.

[0022] The present invention also provides a storage medium storing a computer program, which is called and executed by a computer to realize the modified plastic processing method based on dynamic threshold control as described above. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of a modified plastic processing method based on dynamic threshold control provided in an embodiment of the present invention; Figure 2 This is a flowchart provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a modified plastic processing device based on dynamic threshold control provided in an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0025] In the description of this invention, it should be understood that the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," "third," and "fourth" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a number" means two or more.

[0026] This invention provides a modified plastics processing method based on dynamic threshold control. The method aims to dynamically optimize thresholds based on the thermal aging characteristics of additives and real-time process parameters, forming a closed-loop control through service performance feedback. This constructs a scientific "performance-oriented process design" control method to solve problems such as side-feeding position dependence on empirical rules, and the disconnect between static thresholds and service performance in existing additive addition processes. It improves the processing efficiency and long-life reliability of modified plastics in high-end applications such as lightweight automotive components and new energy battery casings. The method is applicable to various modified plastic systems with added functional additives (such as antioxidants, hydrolysis stabilizers, light stabilizers, flame retardants, etc.), including polyester, nylon, and polyolefins.

[0027] Example 1: Please see Figure 1 The present invention provides a modified plastic processing method based on dynamic threshold control, including S1 to S3, and the specific implementation steps are as follows: S1. Test the mass change of the target additive at several constant temperatures to obtain the thermal degradation characteristic parameters of the target additive.

[0028] Step S1 in this embodiment of the invention specifically includes: The weight loss curves showing the relationship between reaction temperature, time, and degradation rate were obtained by testing the mass change of the target additive at several constant temperatures using a thermogravimetric analyzer (TGA). The target additives include, but are not limited to, toughening modifiers and functional additives, including but not limited to antioxidants, hydrolysis stabilizers, light stabilizers, and flame retardants. In this embodiment, based on 100 parts by weight of the matrix resin (weight units can be grams, kilograms, etc.), the toughening modifier used was DuPont Elvaloy PTW ethylene-butyl acrylate-glycidyl methacrylate terpolymer (5 parts), and the functional additive group included bis-2,6-diisopropylphenyl carbodiimide hydrolysis stabilizer Stabilizer 7000 (1 part) and tris(2,4-di-tert-butylphenyl) phosphite antioxidant 168 (1 part). Furthermore, the "several constant temperatures" used in the testing process were selected and determined based on the resin processing temperature adjacent to the additive addition stage. Based on the weight loss curve, the preset degradation rate is extracted. (e.g., 5% or 10%) The corresponding degradation time at different temperatures; Based on the degradation reaction rate calculation formula, substitute the preset degradation rate D and the corresponding degradation time at different temperatures to calculate the degradation reaction rate at different temperatures, i.e., several degradation reaction rates; Based on a modified form of the Arrhenius equation, a linear regression was performed with the natural logarithm of several degradation reaction rates as the dependent variable and the reciprocal of the Kelvin temperature as the independent variable to obtain a linear equation. Extracting the slope of a linear equation and intercept According to the slope With activation energy Relationship The activation energy was calculated. According to the intercept With pre-exponential factors Relationship The pre-exponential factor is calculated. Ultimately, due to the pre-exponential factor and activation energy The thermal degradation characteristics of the target additive. It should be noted that thermal decomposition reaction is essentially a chemical reaction, and the Arrhenius equation is a classic equation describing the relationship between temperature and reaction rate. It is also applicable to thermal decomposition reaction and can reflect the rule that "increased temperature accelerates thermal decomposition reaction". Based on this, the thermal degradation characteristics can be obtained by solving the Arrhenius equation.

[0029] The formula for calculating the degradation reaction rate is as follows: The Arrhenius equation is: By transforming the Arrhenius equation, we can obtain the natural logarithm of the degradation reaction rate: The linear equation is: for and have: ; in, It is the degradation reaction rate. It is the preset degradation rate. It refers to the pre-factor. It is activation energy; It is the gas constant. ; It is Kelvin temperature, which can also be expressed as .

[0030] This embodiment focuses on the hydrolysis stabilizer Stabilizer 7000. The following examples illustrate the above steps using Stabilizer 7000 as an example: Thermogravimetric analysis (TGA) was used to test the anti-hydrolysis stabilizer Stabilizer 7000 at four constant temperatures: 180℃, 200℃, 220℃, and 240℃. The dynamic change in its mass over time was monitored in real time. Based on the obtained experimental data, the time parameters corresponding to the 0%-100% arbitrary degradation rate of the additive under different temperature conditions can be derived. It should be noted that this embodiment selected four temperatures (180℃, 200℃, 220℃, and 240℃) to test the anti-hydrolysis stabilizer Stabilizer 7000. The core principle is the kinetic extrapolation method adapted to the Arrhenius equation: First, the four temperature points meet the basic requirement of "≥3 temperature points" for this method, allowing the activation energy and pre-exponential factor to be calculated from the test data, establishing a linear mapping relationship between lnk and 1 / T; second, it eliminates the need to measure all temperatures, as this linear relationship allows for quantitative prediction of thermal characteristics at any temperature; and one or two expected operating temperatures can be incorporated into the selection of testing points to further improve prediction accuracy. In this example, the initial threshold for the degradation rate of the additive was set to 10%. Therefore, the time data required for Stabilizer 7000 to reach a 10% degradation rate and the corresponding reaction rate constant were recorded and organized. This yielded the weight loss curve showing the relationship between reaction temperature, time, and degradation rate. The specific results are shown in Table 1. It should be noted that the core of this embodiment is to carry out iterative optimization of the degradation rate threshold. The first threshold was set to 10%, so the test data at this 10% degradation rate was selected for the derivation of the thermodynamic equation.

[0031] The "first threshold" (10% additive degradation rate in this example) is not a fixed value, but an initial quantitative benchmark that is flexibly set according to different application scenarios, characteristics of modified plastic systems, additive types, and performance requirements. For highly heat-sensitive additives, such as some flame retardants, the threshold can be lowered to 5%-8% to minimize thermal degradation. For additives with good stability, such as some antioxidants, the threshold can be raised to 12%-15% to balance processing efficiency and additive utilization. For high-end scenarios such as lightweight automotive parts and new energy battery casings, stringent service performance requirements need to be anchored, and the threshold can be set in a strict range of 5%-10%. For scenarios with relatively relaxed performance requirements, such as ordinary packaging, the threshold can be relaxed to 10%-18%. At the same time, it can also be dynamically adjusted in combination with the processing temperature and material residence time differences of specific plastic systems. The core purpose is to provide a well-defined benchmark for additive thermal degradation kinetic modeling, supporting subsequent Arrhenius equation derivation, side-feeding point positioning, and service performance feedback optimization, ensuring the scientific nature and adaptability of "performance-oriented process design" in different scenarios.

[0032] Table 1 First Comparison Table Based on the weight loss curve and calculated in the above manner, the relevant data corresponding to a 10% mass loss (i.e., a 10% degradation rate) of the hydrolysis stabilizer Stabilizer 7000 determined by thermogravimetric analysis are shown in Table 2. In Table 2, T(K) represents the Kelvin temperature obtained after converting the experimental temperature. The conversion formula is T(K) = T + 273.15, used to meet the temperature unit requirements in the Arrhenius equation. T represents different test temperatures, namely 180℃, 200℃, 220℃, and 240℃. 1 / T(K) -1 ) represents the reciprocal of the Kelvin temperature, and is the independent variable in the linear regression analysis after the transformation of the Arrhenius equation (i.e. The value can be used to transform the nonlinear relationship between reaction rate and temperature into a linear relationship, which facilitates subsequent calculations of activation energy and pre-exponential factor. Represents the reaction rate constant The natural logarithm of is the dependent variable in the linear regression analysis after the transformation of the Arrhenius equation (i.e., value); Table 2 Second Comparison Table The natural logarithm of the degradation reaction rate After performing a linear regression fit on the reciprocal of Kelvin temperature, 1 / T, the corresponding linear equation is obtained as follows: , The activation energy of the reaction can be determined from this. Pre-exponential factor .

[0033] In this embodiment S1, weight loss curves are obtained by testing the mass change of the additive at multiple constant temperatures. This systematically reflects the correlation between reaction temperature, time, and degradation rate, providing an objective experimental basis for subsequent analysis. Based on the weight loss curves, the degradation reaction rate at different temperatures is calculated. Then, thermal degradation characteristic parameters are obtained by combining linear regression with the Arrhenius equation, realizing quantitative modeling of the thermal degradation law of the additive, avoiding errors from empirical judgment, and improving the scientific nature of the parameters. At the same time, this scheme establishes a dynamic correlation between the thermal aging characteristics of the additive and temperature, solving the problems in the prior art where the selection of the side feeding position depends on empirical rules and the lack of a dynamic correlation between the thermal aging life of the additive and processing parameters.

[0034] S2. Based on the set temperature, material residence time, and thermal degradation characteristic parameters of each temperature zone in the twin-screw extruder, calculate the cumulative degradation rate of the target additive from the feed port to the die.

[0035] Step S2 in this embodiment of the invention is specifically as follows: First, determine the basic parameters of each temperature zone in the twin-screw extruder based on the type of base resin used in the modified plastics, including the set temperature T for each zone. set and the residence time of materials in each temperature zone. Furthermore, the set temperature T for each temperature zone is set. set Convert to Kelvin temperature T (K). Wherein, the set temperature T for each temperature zone... se and material residence time The temperature needs to be determined based on the characteristics of the processed material and the parameters of the extruder equipment: generally, the temperature of the die section and the feeding section is lower than the melting point T of the matrix resin. m The temperature of the middle melting section is higher than the material's melting point T. m The temperature of the homogenization section is close to the melting point T of the material. m Material residence time Related to the effective length L of the screw, the screw speed v, and the melt density ρ m and feed density ρ f The relevant basic calculation formula is as follows: = (L / v) × (ρ) m / ρ f ).

[0036] Secondly, based on pre-exponential factors and activation energy By combining the Kelvin temperature T(K) of each temperature zone with the Arrhenius equation, the reaction rate constant corresponding to each temperature zone can be calculated. Then, based on the relationship between degradation rate and time, the degradation rate for each temperature zone was calculated. .

[0037] Finally, the degradation rate of each temperature zone was calculated. By summing these values ​​sequentially, the total degradation rate of the target additive from the feed inlet to the die outlet can be obtained. This refers to the cumulative degradation rate.

[0038] The relationship between degradation rate and time is as follows: in, It is the first Material residence time in the temperature zone It is the first The reaction rate constant in the temperature range, It is the first Degradation rate in the temperature range.

[0039] Furthermore, the technical solution of the present invention is not limited to the dynamic setting of the side feeding point and the improvement of the efficiency of additive utilization in twin-screw extruders. Its process adaptability can also be extended to single-screw extruders, injection molding machines, continuous mixing mills and other plastic processing equipment with temperature control and side feeding functions. By linking the additive thermal degradation kinetic model with real-time process parameters, dynamic processing control optimization of multiple types of equipment can be achieved.

[0040] S3. Based on the cumulative degradation rate, iteratively update the farthest side-feeding point of the safe side-feeding interval until the actual life of the tensile test specimen of the modified plastic is greater than or equal to the target value, and output the final farthest side-feeding point of the target additive in the twin-screw extruder; wherein, the farthest side-feeding point is the position where the cumulative degradation rate is less than or equal to the first threshold; in each iteration, based on the target additive, tensile test specimens are produced according to the farthest side-feeding point of the current iteration, and the tensile performance retention rate and actual life of the tensile test specimen of the current iteration are obtained after the tensile test specimen has undergone a preset aging test; in each iteration, the first threshold is updated according to the preset mechanism.

[0041] Step S3 in this embodiment of the invention includes S3.1 to S3.4, specifically as follows: S3.1 In a twin-screw extruder, if the cumulative degradation rate corresponding to a certain temperature zone is... ≤The preset first threshold, and this position is one of all that satisfy the condition. The temperature range furthest from the feeding section (i.e., closest to the die orifice) within the temperature range ≤ the first threshold is defined as the farthest side-feeding point in the safe side-feeding zone. The safe side-feeding zone refers to the range within which samples prepared using the side-feeding process can meet the expected performance requirements.

[0042] Taking the study of the hydrolysis stabilizer Stabilizer 7000 as an example, the complete process of calculating the cumulative degradation rate and determining the side feeding point in steps S2-S3.1 is as follows: ① Define the extrusion process parameters: Use a ten-zone twin-screw extruder, with each zone temperature T... setThe temperatures were set sequentially to 240℃, 260℃, 260℃, 270℃, 270℃, 260℃, 250℃, 250℃, 240℃, and 240℃, with the material residence time in each temperature zone being 40 seconds. The temperature T of each zone was... set Convert to Kelvin temperature T(K), for example, 240℃ in Zone 1 corresponds to 513.15K; ② Calculate the degradation rate for each temperature zone : Based on pre-exponential factors and activation energy By combining the Kelvin temperature T(K) of each temperature zone with the Arrhenius equation, the reaction rate constant corresponding to each temperature zone can be calculated. ; The reaction rate constant corresponding to each temperature zone Substitute into the relationship between degradation rate and time t=40s; the calculated degradation rates for each temperature zone are: D1=0.01143, D2=0.01492......D 10 =0.01143, as shown in Table 3; Table 3 Third Comparison Table ③ Calculate the cumulative degradation rate and determine the side feeding point: Assuming the first threshold is 10%, and considering the cumulative degradation rate from the die section (zone 10) to the feeding section (zone 1), the results are as follows: ΣD 10 =0.01143、ΣD 10-9 =0.02286、ΣD 10-8 =0.03596、ΣD 10-7 =0.04906、ΣD 10-6 =0.06398、ΣD 10-5 =0.08089、ΣD 10-4 =0.09780、ΣD 10-3 =0.11272 (over 10%)... Therefore, satisfying The furthest side-feeding point with a cumulative degradation rate ≤10% is zone 4, therefore zone 4 is determined as the optimal side-feeding point, where the hydrolysis stabilizer Stabilizer 7000 is added. Furthermore, the degradation rate is accumulated backward from the die section (zone 10) to the feeding section (zone 1) because, in this embodiment, the additive is not fed directly from the feeding port, but rather added through the side-feeding zone. The additive only needs to go through the processing flow of "side-feeding zone → die section." Therefore, accumulating the degradation rate backward from the die end aims to accurately locate the area with a cumulative degradation rate ≤10% (first threshold), thereby determining the appropriate side-feeding zone. This process perfectly matches the actual processing path of the additive.

[0043] It should be noted that in a twin-screw extruder, the feed port is the initial inlet for the material, located at the beginning of the extruder. After entering through the feed port, the material flows sequentially through each temperature zone towards the die. The die is the final outlet for the extruded material, located at the end of the twin-screw extruder. The farthest side feed point refers to a specific side feed position determined during the processing of modified plastics in a twin-screw extruder to optimize the addition process of heat-sensitive additives (such as hydrolysis stabilizers, antioxidants, flame retardants, and light stabilizers). Specifically, it refers to a temperature zone of the extruder where the cumulative degradation rate is less than or equal to a first threshold. "Farthest" means furthest from the die, and the smallest adjustment unit for the side feed port is a temperature zone.

[0044] S3.2. Name the area corresponding to the farthest side feed point as the first area. In the twin-screw extruder, add the target additive to the first area so that the target additive sequentially passes through each temperature zone from the first area to the die. In addition, 30 parts of Owens Corning CS04-183H-13P glass fiber can be selected as a reinforcing material and added to the first area simultaneously with the target additive to complete the additive and reinforcing material addition process settings of the twin-screw extruder. Material is fed into the pre-configured twin-screw extruder through the feed port. By controlling the temperature of each temperature zone of the twin-screw extruder and the shearing action of the screw, the material and the target additive are fully mixed, melted and plasticized, and finally modified plastic is produced. A plastic sample is output from the die. The material can be 53 parts of PBT resin with an intrinsic viscosity of 0.8 dl / g. The screw diameter of the twin-screw extruder is 65 mm and the length-to-diameter ratio (L / D) is 40.

[0045] The plastic sample output from the mold is injection molded according to the preset standard injection molding process, and a tensile test strip conforming to the preset test standard, i.e., a standard strip, is prepared according to the GB / T 1040 standard to provide an experimental carrier for performance evaluation in the subsequent service performance feedback iteration stage.

[0046] The preset standard injection molding process refers to an injection molding process that conforms to industry-standard specifications or specific product standards. Its parameter settings (such as injection temperature, pressure, holding time, and cooling time) must match the characteristics of the modified plastic (such as melt flow index and flowability). For example, for engineering plastics such as PBT resin, standards such as GB / T 17037.1-1997 "Preparation of Injection Molded Specimens for Thermoplastic Materials Part 1: General Principles and Preparation of Multipurpose and Strip Specimens" are typically referenced to ensure a stable injection molding process, avoid defects such as bubbles and shrinkage marks in the specimens due to improper process parameters, and guarantee the consistency of the specimen molding quality.

[0047] Pre-defined testing standards refer to industry or international standards used to standardize the size, shape, and performance testing methods of tensile test specimens. In the performance evaluation of modified plastics, a common example is GB / T 1040.1-2018, "Determination of Tensile Properties of Plastics Part 1: General Rules," which specifies the types of tensile test specimens (e.g., type 1A, type 5A), dimensional tolerances, and testing environment (temperature, humidity). Tensile test specimens prepared in accordance with this standard ensure the accuracy and comparability of tensile performance test data in subsequent aging experiments, providing a reliable evaluation basis for service performance feedback and iteration.

[0048] In this embodiment, S3.2, by adding the target additive to the first region corresponding to the farthest feeding point, the additive only sequentially experiences each temperature zone from that region to the die opening. This allows for strict control of the additive's heat exposure time and intensity during processing, minimizing additive degradation caused by high temperature and high shear, and ensuring the effective utilization rate of the additive in the modified plastic. Based on this, the plastic samples produced and the tensile test strips obtained through injection molding can truly reflect the effect of the target additive under reasonable processing conditions, providing reliable sample support for the accuracy of performance data and the scientific nature of threshold optimization in subsequent aging experiments.

[0049] S3.3 Obtain the initial tensile strength P of the tensile test specimen in its initial state (before undergoing aging test). 0h , as a benchmark value for performance evaluation; A pre-set aging test was conducted on the tensile test specimens. The tensile strength of the tensile test specimens was measured at several intermediate time points and at the end of the test. The tensile strength was then calculated based on the initial tensile strength P. 0h The tensile performance retention rate of the tensile test specimen is calculated by combining the tensile strength at other experimental time points, resulting in a set of tensile performance retention rates for several intermediate time points and a final tensile performance retention rate for the end of the experiment. The pre-set aging experiment refers to an experiment conducted on standard specimens produced by a side-feeding process and injection molding, under pre-set conditions (such as temperature and duration), to evaluate their service performance degradation. Its purpose is to verify the material's performance retention after aging, providing a basis for assessing the rationality of the initially set first threshold and whether to adjust the threshold subsequently; specific types may include thermo-oxidative aging experiments. The "tensile performance retention rate set" refers to the tensile strength of the specimen obtained from several intermediate time points during the pre-set aging experiment, and then the tensile strength at each intermediate time point is compared with the initial tensile strength P of the specimen. 0h The calculation (tensile property retention rate = tensile strength at a certain intermediate time point / initial tensile strength) is performed, and the final data set consists of the tensile property retention rates corresponding to all intermediate time points.

[0050] Based on the tensile performance retention rate set and the final tensile performance retention rate, a dynamic model of performance degradation is fitted according to a polynomial equation. The actual life corresponding to the final tensile performance retention rate of the tensile test specimen is calculated according to the dynamic model. The actual life refers to the actual service time when the tensile performance retention rate of the tensile test specimen drops to the target threshold (50% in this embodiment of the invention). Its value is derived based on actual aging test data, combined with the performance degradation dynamic model fitted by the polynomial equation and the Arrhenius equation. If the final tensile performance retention rate at the end of the experiment is less than the target performance retention rate (50%), or the calculated actual lifespan is shorter than the target lifespan, then the initially set first threshold (i.e., the cumulative degradation rate threshold used to determine the side feeding point, 10%) is deemed unreasonable, and reverse optimization needs to be initiated: Based on the actual lifespan of the tensile test specimen and the preset theoretical lifespan, the actual decay rate of the tensile test specimen is calculated according to the formula "actual decay rate = aging lifespan (i.e., the calculated actual lifespan) / theoretical lifespan". The actual decay rate is used as an adjustment coefficient to reduce the initially set first threshold, resulting in a new first threshold, i.e., the second threshold, to more strictly constrain the degradation rate of the additive during processing, thereby optimizing the side feeding point position and improving the product's service performance. The theoretical lifespan is the duration under ideal conditions, when the additive in the modified plastic product is not affected by additional adverse factors, the product performance can maintain compliance with specific standards. It should be noted that there is a direct quantitative correspondence between the final tensile performance retention rate and the actual lifespan of the tensile test specimen: when the final tensile performance retention rate is lower than the target performance retention rate, the actual lifespan calculated by the performance decay kinetic model fitted by the polynomial equation will inevitably be shorter than the target lifespan. The core purpose of calculating the actual lifespan here is to provide key quantitative basis for the reverse optimization of the first threshold (cumulative degradation rate threshold). Based on the deviation between the actual lifespan and the preset theoretical lifespan, the adjustment coefficient is accurately calculated through the formula "actual decay rate = aging lifespan / theoretical lifespan". This reduces the initial first threshold to obtain a more stringent second threshold, thereby scientifically constraining the degradation rate of additives, optimizing the side feeding point position, and ultimately achieving a targeted improvement in the product's service performance.

[0051] Furthermore, after obtaining a set of tensile performance retention rates corresponding to several intermediate time points, if the tensile performance retention rate at any intermediate time point in the set of tensile performance retention rates measured at several intermediate time points in the preset aging test is less than the target performance retention rate, it is determined that the performance of the tensile test specimen has failed to meet the standard in advance, and there is no need to continue the subsequent aging test. The preset aging test is terminated at the corresponding intermediate time point. At this time, the intermediate time point is regarded as the actual life of the tensile test specimen. Combined with the preset theoretical life, the actual attenuation rate of the tensile test specimen is calculated according to the formula "actual attenuation rate = aging life / theoretical life". The actual attenuation rate is used as an adjustment coefficient to lower and correct the initially set first threshold, resulting in a more stringent second threshold.

[0052] In this embodiment, S3.3, by acquiring the initial tensile strength and the tensile performance retention rate at multiple intermediate time points and the end of the experiment, the dynamic trend of performance degradation can be comprehensively captured, avoiding the limitations of single-time-point data. By combining the fitting of the dynamic model with polynomial equations and calculating the actual life, short-term experimental data is correlated with long-term performance prediction, so that the threshold adjustment is not only based on the measured results, but also incorporates scientific life prediction, enhancing the scientific nature of the decision. At the same time, using the final tensile performance retention rate being less than the target performance retention rate or the actual life being less than the target life as the judgment condition can comprehensively cover the situation of substandard performance, ensuring the timeliness and accuracy of threshold adjustment. Furthermore, by monitoring the tensile performance retention rate at intermediate time points, if any intermediate value falls below the preset target performance retention rate, the aging experiment can be terminated early and threshold adjustment can be triggered. This avoids the waste of time and resources caused by waiting until the end of the experiment, significantly improving the efficiency of process optimization. Simultaneously, this dynamic response mechanism based on intermediate data can detect premature performance degradation earlier, making threshold adjustment more timely. Moreover, using the actual degradation rate as the adjustment coefficient accurately reflects the impact of the processing technology on product performance, ensuring that the correction of the first threshold is directly linked to the product's service performance requirements. This forms a closed-loop optimization from processing to service, improving the reliability and iterative efficiency of process control.

[0053] S3.4 After obtaining the second threshold through reverse optimization, it is necessary to recalculate and determine the new farthest feeding point based on the second threshold, that is, all points that meet the cumulative degradation rate. The temperature zone that is furthest from the feeding section and closest to the die opening section within the temperature zone ≤ the second threshold. Subsequently, the additive addition process of the twin-screw extruder was adjusted according to the newly determined farthest side feed point, and the modified plastic was reproduced and injection molded to obtain new tensile test specimens. The new tensile test specimens underwent a pre-set aging test, and tensile strength was measured at several intermediate time points and the end of the test. The tensile performance retention rate was calculated, and a performance decay kinetic model was fitted based on a polynomial equation to determine the actual lifespan. If the new tensile performance retention rate and actual lifespan still do not meet the target performance requirements, the current threshold is further reduced by adjusting the actual decay rate obtained in the current iteration to obtain the next iteration. Three thresholds are used to re-determine the farthest feeding point and repeat the above production and testing process. The target performance requirements can be dynamically adapted to the modified plastic system (such as PBT, PC / ABS, glass fiber reinforced materials, etc.) and specific application scenarios. The core expression is "tensile property retention rate ≥ X% or actual lifespan ≥ Yh" (in this embodiment, PBT material is used to adapt to lightweight automotive components and new energy battery casings as an example, setting X=50 and Y=5000). The specific definition and setting basis are as follows: ① The target lifespan (Yh) is the aging test duration set for the adapted scenario, which needs to be based on... The minimum reliable service life requirement for a specific plastic system is dynamically determined based on its service environment and application scenarios, aligning with the expected actual service life of the end product. In this embodiment, for the service requirements of PBT material in lightweight automotive components, a target life of Y=5000h is set. ② The tensile property retention rate (X%) is the core performance baseline corresponding to the target life Yh. It needs to be derived based on the material characteristics of the modified plastic, the key functional requirements of the application scenario, and relevant industry standards such as GB / T1040 (Test Method for Tensile Properties of Plastics), to ensure that the material can maintain its performance even after long-term service. Basic usage functions; In this embodiment, considering the mechanical properties of PBT material and the reliability requirements of automotive parts, the tensile performance retention rate X = 50% is set; ③ The specific judgment criteria are: After the corresponding plastic system undergoes an aging test in an appropriate scenario (150℃ thermo-oxidative aging in this embodiment) to Yh, the tensile performance retention rate is not less than X% of the initial value (calculation method: tensile performance retention rate = tensile strength after Yh aging ÷ initial tensile strength at 0h × 100%), or the actual service life calculated by the Arrhenius equation is not less than Yh, then it is considered to have met the target performance requirements; Furthermore, the end of material life refers to the state in which the core performance of a material irreversibly deteriorates and reaches the failure threshold due to factors such as environmental erosion, fatigue accumulation, or aging effects during its service life. "Tensile performance retention rate ≥ 50% after 5000 hours of aging, actual life ≥ target life" is the specific criterion for determining the end of material life in the specific application scenario of this invention. However, the determination of the end of material life is not limited to this. Rather, under standard test conditions, if the mechanical properties (such as strength, toughness, fatigue life, etc.) of the material show significant deterioration, the single-item decline of key functional characteristics (such as conductivity, thermal insulation, magnetic properties, etc.) exceeds the limit, or the physical properties (such as density, dimensional stability, surface quality, etc.) and chemical stability (such as corrosion resistance, oxidation resistance, media compatibility, etc.) indicators break through the corresponding safety thresholds, then the end of material life is determined to have been reached.

[0054] This process is repeated until the final tensile performance retention rate of the tensile test specimen at the end of the experiment is greater than or equal to the target performance retention rate, or the actual life of the tensile test specimen is longer than or equal to the target life. At this point, the farthest side feed point is the final farthest side feed point of the twin-screw extruder, thus ensuring that the modified plastic products produced can meet the requirements of high-end application scenarios for long-life reliability.

[0055] Taking the verification of the thermo-oxidative aging performance and threshold optimization of modified PBT materials as an example, the complete calculation process of steps S3.2-S3.4 is as follows: ① Sample preparation and aging test: PBT resin with an intrinsic viscosity of 0.8 dl / g was fed into a twin-screw extruder set according to the first threshold (10%). The modified PBT material generated by the side-feeding process of the twin-screw extruder was injection molded into national standard tensile test strips at 270℃. The strips were subjected to a thermo-oxidative aging test at 150℃. The tensile strength was tested at 0h, 1000h, 3000h and 5000h respectively. The target was set as ≥50% retention rate of tensile properties after aging for 5000h.

[0056] Initial test results: The tensile strength at 0h was 135MPa, with a tensile performance retention rate of 100%; the tensile strength at 1000h was 102MPa, with a tensile performance retention rate of 75.6%; the tensile strength at 3000h was 76MPa, with a tensile performance retention rate of 56.3% (test error ±2%); and the tensile strength at 5000h was 63MPa, with a tensile performance retention rate of 46.7% (test error ±2%), as shown in Table 4.

[0057] Table 4. Fourth Comparison Table The setting of "test error ±2%" refers to GB / T 1040 "Test Method for Tensile Properties of Plastics". This standard clearly states that the allowable range of laboratory test error for the tensile strength and performance retention rate of plastics is ±1%~3%. This embodiment is a precise laboratory test scenario, and the median value "±2%" is selected as the error control standard.

[0058] ②Performance evaluation and threshold adjustment: The tensile property retention rate after 5000 hours was 46.7% (<50%), and the actual service life F was obtained by fitting a polynomial equation. 50 =3629h (lower than the target value of 5000h), meaning it does not meet the requirement of "tensile property retention rate ≥ 50% after 5000h aging". Therefore, the first threshold (10%) is deemed too high, triggering reverse optimization. The "polynomial equation" refers to the equation with the best fit, selected based on the life fitting requirements of the UL746B standard for long-term thermal aging life assessment of plastics and polymers. This is done by performing second-order and third-order polynomial and exponential fitting on the aging performance data of the tensile test specimen, such as the tensile property retention rate at different time points. The equation is then used to calculate the actual life F corresponding to a decrease in tensile property retention rate to 50%. 50 .

[0059] Based on the formula "actual degradation rate = aging life / theoretical life", the actual degradation rate was initially calculated to be approximately 3629h (aging life) / 5000h (theoretical life) = 72.58%. This degradation rate indicates that the initial 10% degradation rate threshold for additives was too high, resulting in substandard product performance (tensile retention rate of 46.7% < 50% after 5000h). Therefore, the additive degradation rate control standard during the processing stage was revised, adjusting the target threshold from 10% to 7.3%.

[0060] ③ Recalculation and verification: Based on the new threshold of 7.3%, and combined with the calculation results in Table 3 (which records the cumulative degradation rate of each temperature zone in the twin-screw extruder from die zone 10 towards feeding zone 1), the principle of "finding the farthest side feed point with a cumulative degradation rate ≤ 7.3%" was applied. Starting from die zone 10 and gradually increasing the degradation rate towards the feeding zone, the cumulative degradation rate still met the control requirement of ≤ 7.3% when accumulating to zone 6. If the accumulation continued towards zone 5 and further upstream temperature zones, the cumulative degradation rate would exceed the 7.3% threshold. Therefore, zone 6 was determined as the new side feed point. Samples were then re-prepared according to the parameters of this side feed point, and thermo-oxidative aging tests were conducted under the same conditions (150℃, 5000h). "Die zone 10" refers to the 10th temperature control zone at the end of the barrel, immediately adjacent to the final discharge die, which is the last temperature zone the material passes through before extrusion.

[0061] Optimized test results: The tensile strength at 0h is 135MPa, with a tensile performance retention rate of 100%; the tensile strength at 1000h is 110MPa, with a tensile performance retention rate of 81.5%; the tensile strength at 3000h is 90MPa, with a tensile performance retention rate of 66.7%; and the tensile strength at 5000h is 75MPa, with a tensile performance retention rate of 55.6%.

[0062] Verification results: The tensile property retention rate after 5000 hours is 55.6% > 50%, which meets the requirement of "tensile property retention rate ≥ 50% after aging for 5000 hours". The performance meets the standard, and the optimized side-feeding process meets the requirements. The sixth zone is the final and farthest side-feeding point of the twin-screw extruder.

[0063] It should be noted that, in this embodiment, in order to comprehensively evaluate the service performance of modified plastics after side-feeding processing, the aging test needs to measure a wide range of performance dimensions, including but not limited to tensile properties, impact properties, flexural properties, dielectric properties, and flammability. These performance indicators reflect the key performance of materials in actual service environments from different perspectives, such as mechanical properties, electrical insulation, and flame retardancy. Since tensile properties are the basic indicator for measuring the material's resistance to tensile failure, and its decay law can intuitively reflect the effect of additives in the processing and aging process, this embodiment focuses on tensile properties as an example for specific explanation. The testing and analysis logic of other properties can be referred to this example to ensure that the evaluation of the product's service performance is comprehensive and targeted. Furthermore, this invention is applicable to modified plastic systems with various functional additives such as antioxidants, hydrolysis stabilizers, light stabilizers, and flame retardants, covering mainstream substrates such as polyester, nylon, and polyolefins. It can achieve precise optimization of processing technology by quantifying the thermal degradation behavior of additives. Moreover, its applicability is not determined solely by processing temperature, but rather by comprehensively considering the synergistic effects of time and temperature during processing through thermogravimetric kinetic models and residence time distribution analysis. This can significantly improve the utilization rate of additives, avoid waste and side effects such as precipitation and yellowing, and achieve a "performance-oriented" scientific process design.

[0064] For an explanation of the embodiments of the present invention, please refer to [link / reference]. Figure 2 , Figure 2 This is a flowchart provided by an embodiment of the present invention, illustrating the general process of modified plastic processing control in this embodiment.

[0065] Overall, this embodiment has the following beneficial effects: This invention obtains specific thermal degradation characteristic parameters by testing the mass change of target additives at different constant temperatures, providing quantifiable basic data for subsequent analysis. This replaces the vague judgment of additive heat resistance based on traditional experience and avoids positioning deviations caused by differences in additive types. By combining the temperatures of each temperature zone of the twin-screw extruder, the material residence time, and the above thermal degradation parameters, the cumulative degradation rate of the additive from the feed port to the die port is quantitatively calculated. This transforms the selection of the side feeding position from experience-based judgment to data-driven scientific analysis, accurately identifying the range with the lowest degree of additive degradation. The farthest side feeding point is determined based on the standard that the cumulative degradation rate of the additive is less than or equal to a first threshold. This uses a clear numerical standard to replace empirical range delineation, ensuring that the side feeding position is within a safe range where additive degradation is controllable, reducing additive loss due to excessive degradation. The performance of the sample is verified through aging experiments. If the performance does not meet the standard, the threshold is lowered and the side feeding point is redefined, forming an effective closed-loop adjustment. This dynamic optimization ensures that the side feeding position can both reduce additive degradation and meet the final performance requirements of the product, avoiding the problem of static experience rules being out of sync with actual performance, and ultimately achieving an effective improvement in additive utilization. In summary, this invention dynamically optimizes the side feed point position to reduce thermal damage by calculating the cumulative degradation rate based on parameters of each temperature zone of the extruder. It directly links the effective utilization rate of additives with the service performance of the product, and reverse-corrects the process threshold parameters through aging experiments. It integrates the entire process of "modeling-processing-verification" to form an iterative process optimization closed loop, which can be adapted to different modified plastic systems and various heat-sensitive additives, thereby improving the effective utilization rate of additives and enhancing key properties such as weather resistance and flame retardancy of the product to ensure the reliability and stability of high-end application scenarios. It can achieve scientific "performance-oriented process design", and ensures that the process parameters and threshold settings are reasonable through closed-loop control, avoiding the uncertainty of empirical rules. It has wide applicability and good scalability.

[0066] Example 2: Please see Figure 3 The present invention provides a modified plastic processing apparatus based on dynamic threshold control, including a data module 10, a degradation module 20 and an optimization module 30; Among them, data module 10 is used to test the mass change of the target additive at several constant temperatures to obtain the thermal degradation characteristic parameters of the target additive; The degradation module 20 is used to calculate the cumulative degradation rate of the target additive from the feed port to the die port based on the set temperature, material residence time and thermal degradation characteristic parameters of each temperature zone in the twin-screw extruder. The optimization module 30 is used to iteratively update the farthest side-feeding point of the safe side-feeding range based on the cumulative degradation rate until the actual life of the tensile test specimen of the modified plastic is greater than or equal to the target value, and output the final farthest side-feeding point of the target additive in the twin-screw extruder; wherein, the farthest side-feeding point is the position where the cumulative degradation rate is less than or equal to the first threshold; in each iteration, based on the target additive, tensile test specimens are produced according to the farthest side-feeding point of the current iteration, and the tensile performance retention rate and actual life of the tensile test specimen of the current iteration are obtained after the tensile test specimen has undergone a preset aging test; in each iteration, the first threshold is updated according to a preset mechanism.

[0067] In one embodiment, the data module 10 includes a curve unit, a degradation unit, and a parameter unit; The curve unit is used to obtain a weight loss curve showing the relationship between reaction temperature, time, and degradation rate based on the change in mass of the target additive at several constant temperatures over time, as tested by a thermogravimetric analyzer (TGA). The target additive includes, but is not limited to, toughening modifiers and functional additives, including, but not limited to, antioxidants, hydrolysis stabilizers, light stabilizers, and flame retardants. In this embodiment, based on 100 parts by weight of the matrix resin (weight units can be grams, kilograms, etc.), the toughening modifier is DuPont Elvaloy PTW ethylene-butyl acrylate-glycidyl methacrylate terpolymer (5 parts), and the functional additive group includes bis-2,6-diisopropylphenyl carbodiimide hydrolysis stabilizer Stabilizer 7000 (1 part) and tris(2,4-di-tert-butylphenyl) phosphite antioxidant 168 (1 part). Furthermore, the "several constant temperatures" used in the testing process are selected and determined based on the resin processing temperature adjacent to the additive addition stage. The degradation unit is used to extract a preset degradation rate based on the weight loss curve. (e.g., 5% or 10%) The corresponding degradation time at different temperatures; Based on the degradation reaction rate calculation formula, substitute the preset degradation rate D and the corresponding degradation time at different temperatures to calculate the degradation reaction rate at different temperatures, i.e., several degradation reaction rates; The parameter unit is used to perform linear regression based on a modified form of the Arrhenius equation, with the natural logarithm of several degradation reaction rates as the dependent variable and the reciprocal of the Kelvin temperature as the independent variable, to obtain a linear equation. The parameter unit is also used to extract the slope of linear equations. and intercept According to the slope With activation energy Relationship The activation energy was calculated. According to the intercept With pre-exponential factors Relationship The pre-exponential factor is calculated. Ultimately, due to the pre-exponential factor and activation energy The thermal degradation characteristics of the target additive. It should be noted that thermal decomposition reaction is essentially a chemical reaction, and the Arrhenius equation is a classic equation describing the relationship between temperature and reaction rate. It is also applicable to thermal decomposition reaction and can reflect the rule that "increased temperature accelerates thermal decomposition reaction". Based on this, the thermal degradation characteristics can be obtained by solving the Arrhenius equation.

[0068] The formula for calculating the degradation reaction rate is as follows: The Arrhenius equation is: By transforming the Arrhenius equation, we can obtain the natural logarithm of the degradation reaction rate: The linear equation is: for and have: ; in, It is the degradation reaction rate. It is the preset degradation rate. It refers to the pre-factor. It is activation energy; It is the gas constant. ; It is Kelvin temperature, which can also be expressed as .

[0069] This embodiment focuses on the hydrolysis stabilizer Stabilizer 7000. The following examples illustrate the above steps using Stabilizer 7000 as an example: Thermogravimetric analysis (TGA) was used to test the anti-hydrolysis stabilizer Stabilizer 7000 at four constant temperatures: 180℃, 200℃, 220℃, and 240℃. The dynamic change in its mass over time was monitored in real time. Based on the obtained experimental data, the time parameters corresponding to the 0%-100% arbitrary degradation rate of the additive under different temperature conditions can be derived. It should be noted that this embodiment selected four temperatures (180℃, 200℃, 220℃, and 240℃) to test the anti-hydrolysis stabilizer Stabilizer 7000. The core principle is the kinetic extrapolation method adapted to the Arrhenius equation: First, the four temperature points meet the basic requirement of "≥3 temperature points" for this method, allowing the activation energy and pre-exponential factor to be calculated from the test data, establishing a linear mapping relationship between lnk and 1 / T; second, it eliminates the need to measure all temperatures, as this linear relationship allows for quantitative prediction of thermal characteristics at any temperature; and one or two expected operating temperatures can be incorporated into the selection of testing points to further improve prediction accuracy. In this example, the initial threshold for the degradation rate of the additive was set to 10%. Therefore, the time data required for Stabilizer 7000 to reach a 10% degradation rate and the corresponding reaction rate constant were recorded and organized. This yielded the weight loss curve showing the relationship between reaction temperature, time, and degradation rate. The specific results are shown in Table 1. It should be noted that the core of this embodiment is to carry out iterative optimization of the degradation rate threshold. The first threshold was set to 10%, so the test data at this 10% degradation rate was selected for the derivation of the thermodynamic equation.

[0070] The "first threshold" (10% additive degradation rate in this example) is not a fixed value, but an initial quantitative benchmark that is flexibly set according to different application scenarios, characteristics of modified plastic systems, additive types, and performance requirements. For highly heat-sensitive additives, such as some flame retardants, the threshold can be lowered to 5%-8% to minimize thermal degradation. For additives with good stability, such as some antioxidants, the threshold can be raised to 12%-15% to balance processing efficiency and additive utilization. For high-end scenarios such as lightweight automotive parts and new energy battery casings, stringent service performance requirements need to be anchored, and the threshold can be set in a strict range of 5%-10%. For scenarios with relatively relaxed performance requirements, such as ordinary packaging, the threshold can be relaxed to 10%-18%. At the same time, it can also be dynamically adjusted in combination with the processing temperature and material residence time differences of specific plastic systems. The core purpose is to provide a well-defined benchmark for additive thermal degradation kinetic modeling, supporting subsequent Arrhenius equation derivation, side-feeding point positioning, and service performance feedback optimization, ensuring the scientific nature and adaptability of "performance-oriented process design" in different scenarios.

[0071] Table 1 First Comparison Table Based on the weight loss curve and calculated in the above manner, the relevant data corresponding to a 10% mass loss (i.e., a 10% degradation rate) of the hydrolysis stabilizer Stabilizer 7000 determined by thermogravimetric analysis are shown in Table 2. In Table 2, T(K) represents the Kelvin temperature obtained after converting the experimental temperature. The conversion formula is T(K) = T + 273.15, used to meet the temperature unit requirements in the Arrhenius equation. T represents different test temperatures, namely 180℃, 200℃, 220℃, and 240℃. 1 / T(K) -1 ) represents the reciprocal of the Kelvin temperature, and is the independent variable in the linear regression analysis after the transformation of the Arrhenius equation (i.e. The value can be used to transform the nonlinear relationship between reaction rate and temperature into a linear relationship, which facilitates subsequent calculations of activation energy and pre-exponential factor. Represents the reaction rate constant The natural logarithm of is the dependent variable in the linear regression analysis after the transformation of the Arrhenius equation (i.e., value); Table 2 Second Comparison Table The natural logarithm of the degradation reaction rate After performing a linear regression fit on the reciprocal of Kelvin temperature, 1 / T, the corresponding linear equation is obtained as follows: , The activation energy of the reaction can be determined from this. Pre-exponential factor .

[0072] In this embodiment, data module 10 obtains weight loss curves by testing the mass change of the additive at multiple constant temperatures. This systematically reflects the correlation between reaction temperature, time, and degradation rate, providing an objective experimental basis for subsequent analysis. Based on the weight loss curves, the degradation reaction rate at different temperatures is calculated. Then, thermal degradation characteristic parameters are obtained by combining linear regression with the Arrhenius equation, realizing quantitative modeling of the thermal degradation law of the additive, avoiding errors from empirical judgment, and improving the scientific nature of the parameters. At the same time, this scheme establishes a dynamic correlation between the thermal aging characteristics of the additive and temperature, solving the problems in the prior art where the selection of the side feeding position depends on empirical rules and the lack of a dynamic correlation between the thermal aging life of the additive and processing parameters.

[0073] In one embodiment, the degradation module 20 specifically comprises: First, determine the basic parameters of each temperature zone in the twin-screw extruder based on the type of base resin used in the modified plastics, including the set temperature T for each zone. set and the residence time of materials in each temperature zone. Furthermore, the set temperature T for each temperature zone is set. setConvert to Kelvin temperature T (K). Wherein, the set temperature T for each temperature zone... se and material residence time The temperature needs to be determined based on the characteristics of the processed material and the parameters of the extruder equipment: generally, the temperature of the die section and the feeding section is lower than the melting point T of the matrix resin. m The temperature of the middle melting section is higher than the material's melting point T. m The temperature of the homogenization section is close to the melting point T of the material. m Material residence time Related to the effective length L of the screw, the screw speed v, and the melt density ρ m and feed density ρ f The relevant basic calculation formula is as follows: = (L / v) × (ρ) m / ρ f ).

[0074] Secondly, based on pre-exponential factors and activation energy By combining the Kelvin temperature T(K) of each temperature zone with the Arrhenius equation, the reaction rate constant corresponding to each temperature zone can be calculated. Then, based on the relationship between degradation rate and time, the degradation rate for each temperature zone was calculated. .

[0075] Finally, the degradation rate of each temperature zone was calculated. By summing these values ​​sequentially, the total degradation rate of the target additive from the feed inlet to the die outlet can be obtained. This refers to the cumulative degradation rate.

[0076] The relationship between degradation rate and time is as follows: in, It is the first Material residence time in the temperature zone It is the first The reaction rate constant in the temperature range, It is the first Degradation rate in the temperature range.

[0077] Furthermore, the technical solution of the present invention is not limited to the dynamic setting of the side feeding point and the improvement of the efficiency of additive utilization in twin-screw extruders. Its process adaptability can also be extended to single-screw extruders, injection molding machines, continuous mixing mills and other plastic processing equipment with temperature control and side feeding functions. By linking the additive thermal degradation kinetic model with real-time process parameters, dynamic processing control optimization of multiple types of equipment can be achieved.

[0078] In one embodiment, the optimization module 30 includes a first unit, a second unit, a third unit, and a fourth unit; The first unit is used in a twin-screw extruder to determine the cumulative degradation rate at a certain temperature zone. ≤The preset first threshold, and this position is one of all that satisfy the condition. The temperature range furthest from the feeding section (i.e., closest to the die orifice) within the temperature range ≤ the first threshold is defined as the farthest side-feeding point in the safe side-feeding zone. The safe side-feeding zone refers to the range within which samples prepared using the side-feeding process can meet the expected performance requirements.

[0079] Taking the study of the hydrolysis stabilizer Stabilizer 7000 as an example, the complete process of calculating the cumulative degradation rate and determining the side feeding point in steps S2-S3.1 is as follows: ① Define the extrusion process parameters: Use a ten-zone twin-screw extruder, with each zone temperature T... set The temperatures were set sequentially to 240℃, 260℃, 260℃, 270℃, 270℃, 260℃, 250℃, 250℃, 240℃, and 240℃, with the material residence time in each temperature zone being 40 seconds. The temperature T of each zone was... set Convert to Kelvin temperature T(K), for example, 240℃ in Zone 1 corresponds to 513.15K; ② Calculate the degradation rate for each temperature zone : Based on pre-exponential factors and activation energy By combining the Kelvin temperature T(K) of each temperature zone with the Arrhenius equation, the reaction rate constant corresponding to each temperature zone can be calculated. ; The reaction rate constant corresponding to each temperature zone Substitute into the relationship between degradation rate and time t=40s; the calculated degradation rates for each temperature zone are: D1=0.01143, D2=0.01492......D 10 =0.01143, as shown in Table 3; Table 3 Third Comparison Table ③ Calculate the cumulative degradation rate and determine the side feeding point: Assuming the first threshold is 10%, and considering the cumulative degradation rate from the die section (zone 10) to the feeding section (zone 1), the results are as follows: ΣD 10 =0.01143、ΣD 10-9 =0.02286、ΣD 10-8 =0.03596、ΣD 10-7 =0.04906、ΣD 10-6 =0.06398、ΣD 10-5 =0.08089、ΣD 10-4=0.09780、ΣD 10-3 =0.11272 (over 10%)... Therefore, satisfying The furthest side-feeding point with a cumulative degradation rate ≤10% is zone 4, therefore zone 4 is determined as the optimal side-feeding point, where the hydrolysis stabilizer Stabilizer 7000 is added. Furthermore, the degradation rate is accumulated backward from the die section (zone 10) to the feeding section (zone 1) because, in this embodiment, the additive is not fed directly from the feeding port, but rather added through the side-feeding zone. The additive only needs to go through the processing flow of "side-feeding zone → die section." Therefore, accumulating the degradation rate backward from the die end aims to accurately locate the area with a cumulative degradation rate ≤10% (first threshold), thereby determining the appropriate side-feeding zone. This process perfectly matches the actual processing path of the additive.

[0080] It should be noted that in a twin-screw extruder, the feed port is the initial inlet for the material, located at the beginning of the extruder. After entering through the feed port, the material flows sequentially through each temperature zone towards the die. The die is the final outlet for the extruded material, located at the end of the twin-screw extruder. The farthest side feed point refers to a specific side feed position determined during the processing of modified plastics in a twin-screw extruder to optimize the addition process of heat-sensitive additives (such as hydrolysis stabilizers, antioxidants, flame retardants, and light stabilizers). Specifically, it refers to a temperature zone of the extruder where the cumulative degradation rate is less than or equal to a first threshold. "Farthest" means furthest from the die, and the smallest adjustment unit for the side feed port is a temperature zone.

[0081] The second unit is used to name the area corresponding to the farthest feeding point as the first area. In the twin-screw extruder, the target additive is added to the first area, so that the target additive sequentially passes through each temperature zone from the first area to the die. In addition, 30 parts of Owens Corning CS04-183H-13P glass fiber can be selected as a reinforcing material and added to the first area simultaneously with the target additive to complete the additive and reinforcing material addition process settings of the twin-screw extruder. The second unit is also used to feed materials into the set-up twin-screw extruder from the feed port. Through temperature control of each temperature zone of the twin-screw extruder and the shearing action of the screw, the materials and target additives are fully mixed, melted and plasticized to finally produce modified plastics and output plastic samples from the die. The material can be 53 parts of PBT resin with an intrinsic viscosity of 0.8 dl / g. The screw diameter of the twin-screw extruder is 65 mm and the length-to-diameter ratio (L / D) is 40.

[0082] The second unit is also used to process the plastic sample output from the mold through injection molding according to the preset standard injection molding process, and to prepare tensile test strips that meet the preset test standards according to GB / T 1040 standard, i.e., standard strips, to provide experimental carriers for performance evaluation in the subsequent service performance feedback iteration stage.

[0083] The preset standard injection molding process refers to an injection molding process that conforms to industry-standard specifications or specific product standards. Its parameter settings (such as injection temperature, pressure, holding time, and cooling time) must match the characteristics of the modified plastic (such as melt flow index and flowability). For example, for engineering plastics such as PBT resin, standards such as GB / T 17037.1-1997 "Preparation of Injection Molded Specimens for Thermoplastic Materials Part 1: General Principles and Preparation of Multipurpose and Strip Specimens" are typically referenced to ensure a stable injection molding process, avoid defects such as bubbles and shrinkage marks in the specimens due to improper process parameters, and guarantee the consistency of the specimen molding quality.

[0084] Pre-defined testing standards refer to industry or international standards used to standardize the size, shape, and performance testing methods of tensile test specimens. In the performance evaluation of modified plastics, a common example is GB / T 1040.1-2018, "Determination of Tensile Properties of Plastics Part 1: General Rules," which specifies the types of tensile test specimens (e.g., type 1A, type 5A), dimensional tolerances, and testing environment (temperature, humidity). Tensile test specimens prepared in accordance with this standard ensure the accuracy and comparability of tensile performance test data in subsequent aging experiments, providing a reliable evaluation basis for service performance feedback and iteration.

[0085] The second unit of this embodiment adds the target additive to the first region corresponding to the farthest feeding point, so that the additive only sequentially experiences each temperature zone from this region to the die opening. This can strictly control the heat exposure time and intensity of the additive during processing, minimize the degradation of the additive caused by high temperature and high shear, and ensure the effective utilization rate of the additive in the modified plastic. Based on this, the plastic samples produced and the tensile test strips obtained by injection molding can truly reflect the effect of the target additive under reasonable processing conditions, providing reliable sample support for the accuracy of performance data and the scientific nature of threshold optimization in subsequent aging experiments.

[0086] The third unit is used to obtain the initial tensile strength P of the tensile test specimen in its initial state (before undergoing aging tests). 0h , as a benchmark value for performance evaluation; The third unit is also used to conduct a pre-set aging test on the tensile test specimens, taking the tensile strength of the tensile test specimens at several intermediate time points and at the end of the test, and based on the initial tensile strength P... 0hThe tensile performance retention rate of the tensile test specimen is calculated by combining the tensile strength at other experimental time points, resulting in a set of tensile performance retention rates for several intermediate time points and a final tensile performance retention rate for the end of the experiment. The pre-set aging experiment refers to an experiment conducted on standard specimens produced by a side-feeding process and injection molding, under pre-set conditions (such as temperature and duration), to evaluate their service performance degradation. Its purpose is to verify the material's performance retention after aging, providing a basis for assessing the rationality of the initially set first threshold and whether to adjust the threshold subsequently; specific types may include thermo-oxidative aging experiments. The "tensile performance retention rate set" refers to the tensile strength of the specimen obtained from several intermediate time points during the pre-set aging experiment, and then the tensile strength at each intermediate time point is compared with the initial tensile strength P of the specimen. 0h The calculation (tensile property retention rate = tensile strength at a certain intermediate time point / initial tensile strength) is performed, and the final data set consists of the tensile property retention rates corresponding to all intermediate time points.

[0087] The third unit is also used to fit a dynamic model of performance degradation based on the tensile performance retention rate set and the final tensile performance retention rate according to a polynomial equation, and to calculate the actual life corresponding to the final tensile performance retention rate of the tensile test specimen according to the dynamic model; wherein, the actual life refers to the actual service time when the tensile performance retention rate of the tensile test specimen drops to the target threshold (50% in the embodiment of the present invention), and its value is derived based on actual aging test data, combined with the performance degradation dynamic model fitted by the polynomial equation and the Arrhenius equation. The third unit is also used to determine that if the final tensile performance retention rate at the end of the experiment is less than the target performance retention rate (50%), or the calculated actual lifespan is shorter than the target lifespan, the initially set first threshold (i.e., the cumulative degradation rate threshold used to determine the side feeding point, 10%) is unreasonable and reverse optimization needs to be initiated: based on the actual lifespan of the tensile test specimen and the preset theoretical lifespan, the actual decay rate of the tensile test specimen is calculated according to the formula "actual decay rate = aging lifespan (i.e., the calculated actual lifespan) / theoretical lifespan". The actual decay rate is used as an adjustment coefficient to reduce the initially set first threshold, resulting in a new first threshold, i.e., the second threshold, to more strictly constrain the degradation rate of the additive during processing, thereby optimizing the side feeding point position and improving the product's service performance. The theoretical lifespan is the length of time that, under ideal conditions, the additive in the modified plastic product can maintain product performance in accordance with specific standards without being affected by additional adverse factors. It should be noted that there is a direct quantitative correlation between the final tensile performance retention rate and the actual lifespan of the tensile test specimen: when the final tensile performance retention rate is lower than the target performance retention rate, the actual lifespan calculated by the performance degradation kinetic model fitted by the polynomial equation will inevitably be shorter than the target lifespan. The core purpose of calculating the actual lifespan here is to provide a key quantitative basis for the reverse optimization of the first threshold (cumulative degradation rate threshold)—based on the deviation between the actual lifespan and the preset theoretical lifespan, the adjustment coefficient is accurately calculated using the formula "actual degradation rate = aging lifespan / theoretical lifespan," thereby reducing the initial first threshold to obtain a more stringent second threshold. This scientifically constrains the degradation rate of additives during processing, optimizes the side feeding point location, and ultimately achieves a targeted improvement in the product's service performance.

[0088] Furthermore, after obtaining a set of tensile performance retention rates corresponding to several intermediate time points, if the tensile performance retention rate at any intermediate time point in the set of tensile performance retention rates measured at several intermediate time points in the preset aging test is less than the target performance retention rate, it is determined that the performance of the tensile test specimen has failed to meet the standard in advance, and there is no need to continue the subsequent aging test. The preset aging test is terminated at the corresponding intermediate time point. At this time, the intermediate time point is regarded as the actual life of the tensile test specimen. Combined with the preset theoretical life, the actual attenuation rate of the tensile test specimen is calculated according to the formula "actual attenuation rate = aging life / theoretical life". The actual attenuation rate is used as an adjustment coefficient to lower and correct the initially set first threshold, resulting in a more stringent second threshold.

[0089] The third unit in this embodiment can comprehensively capture the dynamic trend of performance degradation by acquiring the initial tensile strength and the tensile performance retention rate at multiple intermediate time points and the end of the experiment, avoiding the limitations of single-time-point data. By combining the fitting of the dynamic model with polynomial equations and calculating the actual life, short-term experimental data is correlated with long-term performance prediction, so that the threshold adjustment is not only based on the measured results, but also incorporates scientific life prediction, enhancing the scientific nature of the decision. At the same time, using the final tensile performance retention rate being less than the target performance retention rate or the actual life being less than the target life as the judgment condition can comprehensively cover the situation of substandard performance, ensuring the timeliness and accuracy of threshold adjustment. Furthermore, by monitoring the tensile performance retention rate at intermediate time points, if any intermediate value falls below the preset target performance retention rate, the aging experiment can be terminated early and threshold adjustment can be triggered. This avoids the waste of time and resources caused by waiting until the end of the experiment, significantly improving the efficiency of process optimization. Simultaneously, this dynamic response mechanism based on intermediate data can detect premature performance degradation earlier, making threshold adjustment more timely. Moreover, using the actual degradation rate as the adjustment coefficient accurately reflects the impact of the processing technology on product performance, ensuring that the correction of the first threshold is directly linked to the product's service performance requirements. This forms a closed-loop optimization from processing to service, improving the reliability and iterative efficiency of process control.

[0090] The fourth unit is used to recalculate and determine the new farthest feeding point after obtaining the second threshold through inverse optimization, i.e., all points that meet the cumulative degradation rate. The temperature zone that is furthest from the feeding section and closest to the die opening section within the temperature zone ≤ the second threshold. Subsequently, the additive addition process of the twin-screw extruder was adjusted according to the newly determined farthest side feed point, and the modified plastic was reproduced and injection molded to obtain new tensile test specimens. The new tensile test specimens underwent a pre-set aging test, and tensile strength was measured at several intermediate time points and the end of the test. The tensile performance retention rate was calculated, and a performance decay kinetic model was fitted based on a polynomial equation to determine the actual lifespan. If the new tensile performance retention rate and actual lifespan still do not meet the target performance requirements, the current threshold is further reduced by adjusting the actual decay rate obtained in the current iteration to obtain the next iteration. Three thresholds are used to re-determine the farthest feeding point and repeat the above production and testing process. The target performance requirements can be dynamically adapted to the modified plastic system (such as PBT, PC / ABS, glass fiber reinforced materials, etc.) and specific application scenarios. The core expression is "tensile property retention rate ≥ X% or actual lifespan ≥ Yh" (in this embodiment, PBT material is used to adapt to lightweight automotive components and new energy battery casings as an example, setting X=50 and Y=5000). The specific definition and setting basis are as follows: ① The target lifespan (Yh) is the aging test duration set for the adapted scenario, which needs to be based on... The minimum reliable service life requirement for a specific plastic system is dynamically determined based on its service environment and application scenarios, aligning with the expected actual service life of the end product. In this embodiment, for the service requirements of PBT material in lightweight automotive components, a target life of Y=5000h is set. ② The tensile property retention rate (X%) is the core performance baseline corresponding to the target life Yh. It needs to be derived based on the material characteristics of the modified plastic, the key functional requirements of the application scenario, and relevant industry standards such as GB / T1040 (Test Method for Tensile Properties of Plastics), to ensure that the material can maintain its performance even after long-term service. Basic usage functions; In this embodiment, considering the mechanical properties of PBT material and the reliability requirements of automotive parts, the tensile performance retention rate X = 50% is set; ③ The specific judgment criteria are: After the corresponding plastic system undergoes an aging test in an appropriate scenario (150℃ thermo-oxidative aging in this embodiment) to Yh, the tensile performance retention rate is not less than X% of the initial value (calculation method: tensile performance retention rate = tensile strength after Yh aging ÷ initial tensile strength at 0h × 100%), or the actual service life calculated by the Arrhenius equation is not less than Yh, then it is considered to have met the target performance requirements; Furthermore, the end of material life refers to the state in which the core performance of a material irreversibly deteriorates and reaches the failure threshold due to factors such as environmental erosion, fatigue accumulation, or aging effects during its service life. "Tensile performance retention rate ≥ 50% after 5000 hours of aging, actual life ≥ target life" is the specific criterion for determining the end of material life in the specific application scenario of this invention. However, the determination of the end of material life is not limited to this. Rather, under standard test conditions, if the mechanical properties (such as strength, toughness, fatigue life, etc.) of the material show significant deterioration, the single-item decline of key functional characteristics (such as conductivity, thermal insulation, magnetic properties, etc.) exceeds the limit, or the physical properties (such as density, dimensional stability, surface quality, etc.) and chemical stability (such as corrosion resistance, oxidation resistance, media compatibility, etc.) indicators break through the corresponding safety thresholds, then the end of material life is determined to have been reached.

[0091] This process is repeated until the final tensile performance retention rate of the tensile test specimen at the end of the experiment is greater than or equal to the target performance retention rate, or the actual life of the tensile test specimen is longer than or equal to the target life. At this point, the farthest side feed point is the final farthest side feed point of the twin-screw extruder, thus ensuring that the modified plastic products produced can meet the requirements of high-end application scenarios for long-life reliability.

[0092] Taking the verification of the thermo-oxidative aging performance and threshold optimization of modified PBT materials as an example, the complete calculation process of steps S3.2-S3.4 is as follows: ① Sample preparation and aging test: PBT resin with an intrinsic viscosity of 0.8 dl / g was fed into a twin-screw extruder set according to the first threshold (10%). The modified PBT material generated by the side-feeding process of the twin-screw extruder was injection molded into national standard tensile test strips at 270℃. The strips were subjected to a thermo-oxidative aging test at 150℃. The tensile strength was tested at 0h, 1000h, 3000h and 5000h respectively. The target was set as ≥50% retention rate of tensile properties after aging for 5000h.

[0093] Initial test results: The tensile strength at 0h was 135MPa, with a tensile performance retention rate of 100%; the tensile strength at 1000h was 102MPa, with a tensile performance retention rate of 75.6%; the tensile strength at 3000h was 76MPa, with a tensile performance retention rate of 56.3% (test error ±2%); and the tensile strength at 5000h was 63MPa, with a tensile performance retention rate of 46.7% (test error ±2%), as shown in Table 4.

[0094] Table 4. Fourth Comparison Table The setting of "test error ±2%" refers to GB / T 1040 "Test Method for Tensile Properties of Plastics". This standard clearly states that the allowable range of laboratory test error for the tensile strength and performance retention rate of plastics is ±1%~3%. This embodiment is a precise laboratory test scenario, and the median value "±2%" is selected as the error control standard.

[0095] ②Performance evaluation and threshold adjustment: The tensile property retention rate after 5000 hours was 46.7% (<50%), and the actual service life F was obtained by fitting a polynomial equation. 50 =3629h (lower than the target value of 5000h), meaning it does not meet the requirement of "tensile property retention rate ≥ 50% after 5000h aging". Therefore, the first threshold (10%) is deemed too high, triggering reverse optimization. The "polynomial equation" refers to the equation with the best fit, selected based on the life fitting requirements of the UL746B standard for long-term thermal aging life assessment of plastics and polymers. This is done by performing second-order and third-order polynomial and exponential fitting on the aging performance data of the tensile test specimen, such as the tensile property retention rate at different time points. The equation is then used to calculate the actual life F corresponding to a decrease in tensile property retention rate to 50%. 50 .

[0096] Based on the formula "actual degradation rate = aging life / theoretical life", the actual degradation rate was initially calculated to be approximately 3629h (aging life) / 5000h (theoretical life) = 72.58%. This degradation rate indicates that the initial 10% degradation rate threshold for additives was too high, resulting in substandard product performance (tensile retention rate of 46.7% < 50% after 5000h). Therefore, the additive degradation rate control standard during the processing stage was revised, adjusting the target threshold from 10% to 7.3%.

[0097] ③ Recalculation and verification: Based on the new threshold of 7.3%, and combined with the calculation results in Table 3 (which records the cumulative degradation rate of each temperature zone in the twin-screw extruder from die zone 10 towards feeding zone 1), the principle of "finding the farthest side feed point with a cumulative degradation rate ≤ 7.3%" was applied. Starting from die zone 10 and gradually increasing the degradation rate towards the feeding zone, the cumulative degradation rate still met the control requirement of ≤ 7.3% when accumulating to zone 6. If the accumulation continued towards zone 5 and further upstream temperature zones, the cumulative degradation rate would exceed the 7.3% threshold. Therefore, zone 6 was determined as the new side feed point. Samples were then re-prepared according to the parameters of this side feed point, and thermo-oxidative aging tests were conducted under the same conditions (150℃, 5000h). "Die zone 10" refers to the 10th temperature control zone at the end of the barrel, immediately adjacent to the final discharge die, which is the last temperature zone the material passes through before extrusion.

[0098] Optimized test results: The tensile strength at 0h is 135MPa, with a tensile performance retention rate of 100%; the tensile strength at 1000h is 110MPa, with a tensile performance retention rate of 81.5%; the tensile strength at 3000h is 90MPa, with a tensile performance retention rate of 66.7%; and the tensile strength at 5000h is 75MPa, with a tensile performance retention rate of 55.6%.

[0099] Verification results: The tensile property retention rate after 5000 hours is 55.6% > 50%, which meets the requirement of "tensile property retention rate ≥ 50% after aging for 5000 hours". The performance meets the standard, and the optimized side-feeding process meets the requirements. The sixth zone is the final and farthest side-feeding point of the twin-screw extruder.

[0100] It should be noted that, in this embodiment, in order to comprehensively evaluate the service performance of modified plastics after side-feeding processing, the aging test needs to measure a wide range of performance dimensions, including but not limited to tensile properties, impact properties, flexural properties, dielectric properties, and flammability. These performance indicators reflect the key performance of materials in actual service environments from different perspectives, such as mechanical properties, electrical insulation, and flame retardancy. Since tensile properties are the basic indicator for measuring the material's resistance to tensile failure, and its decay law can intuitively reflect the effect of additives in the processing and aging process, this embodiment focuses on tensile properties as an example for specific explanation. The testing and analysis logic of other properties can be referred to this example to ensure that the evaluation of the product's service performance is comprehensive and targeted. Furthermore, this invention is applicable to modified plastic systems with various functional additives such as antioxidants, hydrolysis stabilizers, light stabilizers, and flame retardants, covering mainstream substrates such as polyester, nylon, and polyolefins. It can achieve precise optimization of processing technology by quantifying the thermal degradation behavior of additives. Moreover, its applicability is not determined solely by processing temperature, but rather by comprehensively considering the synergistic effects of time and temperature during processing through thermogravimetric kinetic models and residence time distribution analysis. This can significantly improve the utilization rate of additives, avoid waste and side effects such as precipitation and yellowing, and achieve a "performance-oriented" scientific process design.

[0101] For an explanation of the embodiments of the present invention, please refer to [link / reference]. Figure 2 , Figure 2 This is a flowchart provided by an embodiment of the present invention, illustrating the general process of modified plastic processing control in this embodiment.

[0102] Overall, this embodiment has the following beneficial effects: This invention obtains specific thermal degradation characteristic parameters by testing the mass change of target additives at different constant temperatures, providing quantifiable basic data for subsequent analysis. This replaces the vague judgment of additive heat resistance based on traditional experience and avoids positioning deviations caused by differences in additive types. By combining the temperatures of each temperature zone of the twin-screw extruder, the material residence time, and the above thermal degradation parameters, the cumulative degradation rate of the additive from the feed port to the die port is quantitatively calculated. This transforms the selection of the side feeding position from experience-based judgment to data-driven scientific analysis, accurately identifying the range with the lowest degree of additive degradation. The farthest side feeding point is determined based on the standard that the cumulative degradation rate of the additive is less than or equal to a first threshold. This uses a clear numerical standard to replace empirical range delineation, ensuring that the side feeding position is within a safe range where additive degradation is controllable, reducing additive loss due to excessive degradation. The performance of the sample is verified through aging experiments. If the performance does not meet the standard, the threshold is lowered and the side feeding point is redefined, forming an effective closed-loop adjustment. This dynamic optimization ensures that the side feeding position can both reduce additive degradation and meet the final performance requirements of the product, avoiding the problem of static experience rules being out of sync with actual performance, and ultimately achieving an effective improvement in additive utilization. In summary, this invention dynamically optimizes the side feed point position to reduce thermal damage by calculating the cumulative degradation rate based on parameters of each temperature zone of the extruder. It directly links the effective utilization rate of additives with the service performance of the product, and reverse-corrects the process threshold parameters through aging experiments. It integrates the entire process of "modeling-processing-verification" to form an iterative process optimization closed loop, which can be adapted to different modified plastic systems and various heat-sensitive additives, thereby improving the effective utilization rate of additives and enhancing key properties such as weather resistance and flame retardancy of the product to ensure the reliability and stability of high-end application scenarios. It can achieve scientific "performance-oriented process design", and ensures that the process parameters and threshold settings are reasonable through closed-loop control, avoiding the uncertainty of empirical rules. It has wide applicability and good scalability.

[0103] Example 3: This invention provides a computer-readable storage medium including a stored computer program, wherein the computer program, when running, controls the device where the computer-readable storage medium is located to execute the modified plastic processing method based on dynamic threshold control. The modified plastic processing method based on dynamic threshold control, when implemented as a software functional unit and used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments can also be implemented by a computer program instructing related hardware. This computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0104] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A modified plastic processing method based on dynamic threshold control, characterized in that, include: The mass change of the target additive at several constant temperatures was tested to obtain the thermal degradation characteristic parameters of the target additive; Based on the set temperature of each temperature zone in the twin-screw extruder, the material residence time, and the thermal degradation characteristic parameters, the cumulative degradation rate of the target additive from the feed port to the die port is calculated. Based on the cumulative degradation rate, the farthest side-feeding point of the safe side-feeding interval is iteratively updated until the actual life of the tensile test specimen of the modified plastic is greater than or equal to the target value, and the final farthest side-feeding point of the target additive in the twin-screw extruder is output; wherein, the farthest side-feeding point is the position where the cumulative degradation rate is less than or equal to the first threshold; in each iteration, based on the target additive, tensile test specimens are produced according to the farthest side-feeding point of the current iteration, and the tensile performance retention rate and actual life of the tensile test specimen of the current iteration are obtained after the tensile test specimen has undergone a preset aging test; During each iteration, the first threshold is updated according to a preset mechanism.

2. The modified plastic processing method based on dynamic threshold control as described in claim 1, characterized in that, The mass change of the target additive at several constant temperatures was tested to obtain the thermal degradation characteristic parameters of the target additive, specifically including: The mass change of the target adjuvant at several constant temperatures was tested to obtain the weight loss curves relating reaction temperature, time, and degradation rate. The degradation time corresponding to different temperatures at the target degradation rate is obtained based on the weight loss curve. The degradation reaction rate at different temperatures is calculated based on the target degradation rate and the corresponding degradation time to obtain several degradation reaction rates. Based on the Arrhenius equation, linear regression was performed on the natural logarithm set of the degradation reaction rates and the reciprocal of the Kelvin temperature to obtain the thermal degradation characteristic parameters of the target adjuvant.

3. The modified plastic processing method based on dynamic threshold control as described in claim 1, characterized in that, Based on the cumulative degradation rate, the furthest side-feed point in the safe side-feed interval is iteratively updated until the actual lifespan of the tensile test specimen of the modified plastic is greater than or equal to the target value. The final furthest side-feed point of the target additive in the twin-screw extruder is then output, specifically including: During each iteration, the position where the cumulative degradation rate is less than or equal to the first threshold is defined as the farthest side-feeding point of the safe side-feeding interval; The tensile test specimen is produced based on the farthest feeding point, and the initial tensile strength of the tensile test specimen in the initial state is obtained. The tensile test specimen is subjected to the preset aging test. The tensile strength of the tensile test specimen is taken at several intermediate time points and at the end of the test. The tensile performance retention rate of the tensile test specimen is calculated based on the initial tensile strength and the tensile strength. The tensile performance retention rate set corresponding to the several intermediate time points and the final tensile performance retention rate corresponding to the end of the test are obtained respectively. Based on the set of tensile performance retention rates and the final tensile performance retention rate, a dynamic model of performance decay is fitted according to a polynomial equation, and the actual life corresponding to the tensile performance retention rate of the tensile test specimen is calculated according to the dynamic model. If the final tensile performance retention rate is less than the target performance retention rate, or the actual lifespan is shorter than the target lifespan, then the first threshold is updated according to the preset mechanism and the next iteration is entered to obtain the second preset threshold, until the final tensile performance retention rate of the tensile test specimen is greater than or equal to the target performance retention rate, or the actual lifespan is longer than or equal to the target lifespan, and the final farthest feeding point of the target additive in the twin-screw extruder is output.

4. The modified plastic processing method based on dynamic threshold control as described in claim 3, characterized in that, After obtaining the set of tensile property retention rates corresponding to the aforementioned intermediate time points, the method further includes: If any tensile performance retention rate in the set of tensile performance retention rates is less than the target performance retention rate, the preset aging experiment ends at the corresponding intermediate time point, and the first threshold is updated according to the preset mechanism.

5. The modified plastic processing method based on dynamic threshold control as described in claim 1, characterized in that, In each iteration, based on the target additive, tensile test specimens are produced according to the farthest feeding point of the current iteration, specifically including: During each iteration, in the twin-screw extruder, the target additive is added to the first region corresponding to the farthest feed point of the current iteration, so that the target additive sequentially experiences each temperature zone from the first region to the die orifice; Modified plastics are produced using the configured twin-screw extruder to obtain plastic samples; The plastic sample is injection molded to obtain the tensile test strip that meets the preset test standards.

6. A modified plastic processing method based on dynamic threshold control as described in any one of claims 1-5, characterized in that, The first threshold is updated according to a preset mechanism, specifically including: The actual attenuation rate of the tensile test specimen is calculated based on the actual lifespan and the preset theoretical lifespan. The actual attenuation rate is then used as an adjustment coefficient to reduce the first threshold of the additive degradation rate, resulting in an updated first threshold.

7. A modified plastic processing method based on dynamic threshold control as described in any one of claims 1-5, characterized in that, The feed port is the initial inlet for the material to enter the twin-screw extruder, located at the beginning of the twin-screw extruder. After entering through the feed port, the material flows sequentially through each temperature zone and moves toward the die. The die is the final outlet for the material to be extruded and formed, located at the end of the twin-screw extruder.

8. A modified plastic processing apparatus based on dynamic threshold control, characterized in that, It includes a data module, a degradation module, and an optimization module; The data module is used to test the mass change of the target additive at several constant temperatures to obtain the thermal degradation characteristic parameters of the target additive. The degradation module is used to calculate the cumulative degradation rate of the target additive from the feed inlet to the die orifice based on the set temperature of each temperature zone in the twin-screw extruder, the material residence time, and the thermal degradation characteristic parameters. The optimization module is used to iteratively update the farthest side-feeding point of the safe side-feeding interval according to the cumulative degradation rate, until the actual life of the tensile test specimen of the modified plastic is greater than or equal to the target value, and output the final farthest side-feeding point of the target additive in the twin-screw extruder; wherein, the farthest side-feeding point is the position where the cumulative degradation rate is less than or equal to a first threshold; in each iteration, based on the target additive, tensile test specimens are produced according to the farthest side-feeding point of the current iteration, and the tensile performance retention rate and actual life of the tensile test specimens of the current iteration are obtained after the tensile test specimens undergo a preset aging test; in each iteration, the first threshold is updated according to a preset mechanism.

9. The modified plastic processing apparatus based on dynamic threshold control as described in claim 8, characterized in that, The data module includes a curve unit, a degradation unit, and a parameter unit; The curve unit is used to test the mass change of the target adjuvant at several constant temperatures to obtain a weight loss curve showing the relationship between reaction temperature, time, and degradation rate. The degradation unit is used to obtain the degradation time corresponding to different temperatures at the target degradation rate based on the weight loss curve, and to calculate the degradation reaction rate at different temperatures based on the target degradation rate and the corresponding degradation time, thereby obtaining several degradation reaction rates. The parameter unit is used to perform linear regression on the set of natural logarithms of the several degradation reaction rates and the reciprocal of the Kelvin temperature based on the Arrhenius equation to obtain the thermal degradation characteristic parameters of the target adjuvant.

10. A storage medium, characterized in that, The storage medium stores a computer program, which is called and executed by a computer to implement a modified plastic processing method based on dynamic threshold control as described in any one of claims 1 to 7.

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