A Method for Determining the Synchronous Radiation of a Crystalline Plastic Injection Window

Abstract

The present invention provides a method for determining the synchrotron radiation of a crystalline plastic injection window, which relates to the field of on-line detection of crystalline plastic injection molding and can be combined with synchrotron radiation X-ray scattering experimental technology to obtain methods for regulating the product structure with different processing parameters during the injection molding process of polymer materials. By respectively establishing the relationships between crystallinity, crystal form content, lamellar thickness, crystallization time and orientation degree and process parameters, the optimal process for the required structure can be obtained. In this way, the multi-scale structure evolution and kinetic parameters of the polymer under different processing technologies are obtained, realizing the on-line monitoring of the structure of the polymer melt in the injection molding die and the efficient determination of the injection processing window. This method first applies synchrotron radiation technology to monitor the processing of three-dimensional components, has strong versatility, high measurement accuracy, is convenient and practical, and can independently seek the best parameters for injection processing, thereby realizing intelligent injection molding and achieving the required service performance.

Description

Technical Field

[0001] The present invention relates to the field of on-line detection of crystalline plastic injection molding, and relates to, but is not limited to, a method for determining the synchrotron radiation of a crystalline plastic injection window. Background Art

[0002] In the field of polymer injection molding, it is crucial to precisely control processing parameters to optimize product performance and processing efficiency. Traditional injection molding methods often rely on empirical settings, mostly focusing on the stability of the product production process and the consistency of product quality, lacking real-time monitoring and quantitative analysis of the flow, cooling, and crystallization processes of polymer melts in the mold. This results in the determination of the processing window often requiring a large amount of trial and error, which is not only time-consuming and laborious but also costly.

[0003] With the development of digitalization and networking, sensor technology plays an important role in Industry 4.0. Although it can provide real-time temperature and pressure data to help optimize the injection molding process, its ability to directly obtain product structure information is limited. Therefore, it is necessary to further achieve real-time and quantitative analysis of the microstructure of polymer melts, so as to more precisely determine the injection molding processing window and improve product quality and production efficiency.

[0004] However, during the injection molding process, the polymer structure has multi-scale characteristics and rapidly evolves within seconds under a complex thermo-mechanical environment. Therefore, it is difficult to obtain the kinetic characteristics of structure formation through characterization methods such as in-situ Raman microscopy, in-situ optical microscopy, and neutron scattering. The synchrotron radiation X-ray diffraction (scattering) technology has the advantages of high throughput, high penetration (sample thickness in millimeters), and millisecond-level time resolution ability, and has been used for in-situ characterization of laboratory small-scale instrument experiments such as rotational rheology. Chinese Patent CN 107063889 B provides a creep tensile device combined with X-ray scattering, but this device is used for the molding of simple two-dimensional products (films). How to combine synchrotron radiation X-ray in-situ characterization with the installation of complex three-dimensional product molding instruments is still a challenge. The spatial limitations of industrial equipment installation on the beamline, the mold design for in-situ characterization, and the alignment of the X-ray beam are also technical problems that need to be solved first. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention proposes a method for determining the synchrotron radiation of a crystalline plastic injection window, which can obtain microstructure information such as crystallization kinetics, polymorphism evolution, and growth and orientation of polymer lamellae during the injection molding process of semi-crystalline polymers without damaging the injection samples, and efficiently determines the polymer injection molding processing window.

[0006] The technical method of the embodiment of the present invention is realized as follows:

[0007] In a first aspect, an embodiment of the present invention provides a method for determining synchrotron radiation of a crystalline plastic injection molding window, and the method includes:

[0008] S1. Obtain the test injection molding process parameters and test crystal structure parameters of the plastic to be injection molded, and design an orthogonal experiment;

[0009] S2. Apply the process parameters to an injection molding experiment, and during the experiment, a wide-angle / small-angle X-ray scattering detector is used in combination to obtain two-dimensional scattering image data of the melt at the center of the injection mold in real time;

[0010] S3. Perform data processing and integral processing on the two-dimensional scattering image data in sequence to obtain the scattering vector-scattering intensity curves of the plastic to be injection molded at wide-angle and small-angle scales; and based on the scattering vector-scattering intensity curves, obtain the crystal structure parameters of the plastic to be injection molded; the structure parameters include crystallization time, crystallinity, orientation degree, and lamellar thickness;

[0011] S4. Perform correlation analysis on the test injection molding process parameters and the crystal structure parameters, establish the relationships of crystallinity-process parameters, crystal form content-process parameters, lamellar thickness-process parameters, crystallization time-process parameters, and orientation degree-process parameters; and plot multiple relationships into a double coordinate graph to obtain a three-parameter injection molding processing window.

[0012] In some embodiments, when establishing the relationship of crystallization time-process parameters, the crystallization time Δt of the polymer is calculated by the following formula: ; where t 0 is the starting moment of polymer crystallization, and t peak is the moment when the diffraction intensity of the polymer crystal plane reaches saturation; the growth conditions of different crystal planes of the polymer are obtained through a one-dimensional wide-angle X-ray scattering curve, and the crystal plane with the strongest diffraction peak is selected to characterize the crystal crystallization kinetics; by establishing the relationship between time and crystal plane intensity, a scattering intensity-time curve is plotted, and t 0 and t peak are observed from the curve.

[0013] In some embodiments, when establishing the relationship of crystal form content-process parameters, the crystal form content of the polymer is expressed as the ratio of the sum of the peak areas of all crystal planes included in one crystal form to the peak areas of all crystal form crystal planes. By performing peak fitting on the one-dimensional wide-angle X-ray scattering curve, the peak area A hkl of each crystal plane is obtained.

[0014] In some embodiments, through the one-dimensional wide-angle X-ray scattering curve, the areas of each crystal peak and amorphous peak are obtained, and the overall crystallinity Xc of the polymer is calculated by the following formula:

[0015] ;

[0016] In the formula, refers to the area of each crystal peak, represents the area of the amorphous peak.

[0017] In some embodiments, when establishing the relationship between the degree of orientation and process parameters, the degree of orientation f H is calculated by the following formula:

[0018]

[0019] In the formula, refers to the orientation factor, which is calculated by the following formula:

[0020]

[0021] In the formula, is the angle between the normal of the given (hkl) crystal plane and the reference direction, is along the angle of the diffraction intensity.

[0022] In some embodiments, when establishing the relationship between the lamellar thickness and process parameters, the lamellar thickness is calculated based on an ideal two-phase lamellar microstructure model. The scattering vector-scattering intensity curve at the small-angle scale is Fourier-transformed to obtain a one-dimensional electron cloud density function , and the target structure parameter is extracted by analyzing the one-dimensional electron cloud density function: the target structure parameter is the average thickness d of the crystalline layer c , where the one-dimensional electron cloud density function has the following expression:

[0023] ;

[0024] In the formula, represents the electron density distribution in the z direction, z represents the distance in real space; q represents the small-angle scattering vector.

[0025] The synchrotron radiation determination method for the injection molding window of crystalline plastics provided by the embodiments of the present invention can be combined with synchrotron radiation X-ray scattering experimental technology to obtain methods for regulating product structures with different processing parameters during the injection molding process of polymer materials. By establishing the relationships between crystallinity - process parameters, crystal form content - process parameters, lamellar thickness - process parameters, crystallization time - process parameters, and orientation degree - process parameters, the optimal process for the required structure can be obtained. In this way, the present invention converts X-ray diffraction and scattering information into changes in the multi-scale structure of polymers during the injection molding process, and then obtains the evolution of the multi-scale structure of polymers and kinetic parameters under different processing technologies, realizing the on-line monitoring of the structure of polymer melts in the injection molding die and the efficient determination of the injection processing window. It has strong versatility, high measurement accuracy, is convenient and practical, and breaks the black box mode in the traditional injection molding structure. In addition, the present invention extends synchrotron radiation technology from laboratory static analysis to industrial-level dynamic processing process monitoring, directly serving the optimization of injection molding processes; and integrates the real-time correlations of multiple structure parameters and kinetic parameters with process parameters, breaking through the limitations of traditional single-variable optimization; through the structure data feedback by synchrotron radiation to drive the automatic adjustment of injection molding machine parameters, forming a "monitoring - analysis - regulation" closed-loop system to achieve intelligent injection molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic flow chart of a synchrotron radiation determination method for the injection molding window of crystalline plastics provided by the embodiments of the present invention;

[0027] Figure 2 (a) is a physical diagram of an industrial-grade injection molding machine provided by the embodiments of the present invention, Figure 2 (b) is a remote operation platform provided by the embodiments of the present invention, Figure 2 (c - d) are experimental combined SAXS / WAXS detectors provided by the embodiments of the present invention;

[0028] Figure 3 is a schematic flow chart of a method for determining the polymer processing window in injection molding provided by the embodiments of the present invention;

[0029] Figure 4 is a schematic flow chart of a method for determining the polymer crystallization time processing window in injection molding provided by the embodiments of the present invention;

[0030] Figure 5 (a) is a graph of the polyethylene crystallization time processing window provided by the embodiments of the present invention, Figure 5 (b) is a graph of the polypropylene α-crystal crystallization time processing window provided by the embodiments of the present invention, Figure 5 (c) is the poly(lactic acid) crystallization time processing window provided by the embodiments of the present invention, Figure 5 (d) is the nylon 6 crystallization time processing window provided by the embodiments of the present invention;

[0031] Figure 6 (a) is the crystallinity injection molding processing window provided by the embodiment of the present invention, Figure 6 (b) is the lamellar thickness injection molding processing window provided by the embodiment of the present invention, Figure 6 (c) is the crystal orientation injection molding processing window provided by the embodiment of the present invention;

[0032] Figure 7 is the polypropylene polymorph distribution processing window provided by the embodiment of the present invention, Figure 7 (a-c) respectively refer to the crystal content distribution windows of polypropylene α-crystal, β-crystal, and γ-crystal under different injection rates and holding pressures. Detailed implementation manners

[0033] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be construed as limiting the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0034] In the following description, reference is made to "some embodiments", which describe subsets of all possible embodiments. However, it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict. Unless otherwise defined, all technical and scientific terms used in the embodiments of the present invention have the same meaning as commonly understood by those skilled in the technical field to which the embodiments of the present invention belong. The terms used in the embodiments of the present invention are only for the purpose of describing the embodiments of the present invention and are not intended to limit the present invention.

[0035] The embodiment of the present invention provides a synchrotron radiation determination method for the injection molding window of crystalline plastics. Refer to Figure 1 , Figure 1 is the flow schematic diagram of the synchrotron radiation determination method for the injection molding window of crystalline plastics provided by the embodiment of the present invention, and will be described in conjunction with Figure 1 the steps shown.

[0036] Step S1, obtain the test injection molding process parameters and test crystal structure parameters of the plastic to be injection molded, and design an orthogonal experiment.

[0037] Step S2, apply the process parameters to the injection molding experiment, and use a wide-angle / small-angle X-ray scattering detector during the experiment to obtain the two-dimensional scattering image data of the melt at the center of the injection mold in real time;

[0038] Step S3: Perform data processing and integral processing on the two-dimensional scattering image data in sequence to obtain the scattering vector-scattering intensity curves of the plastic to be injection-molded at wide-angle and small-angle scales; and based on the scattering vector-scattering intensity curves, obtain the crystal structure parameters of the plastic to be injection-molded; the structure parameters include crystallization time, crystallinity, orientation degree, and lamellar thickness.

[0039] Step S4: Conduct correlation analysis on the test injection molding process parameters and the crystal structure parameters to establish the relationships between crystallinity-process parameters, crystal form content-process parameters, lamellar thickness-process parameters, crystallization time-process parameters, and orientation degree-process parameters; and plot multiple relationships into a double-coordinate graph to obtain a three-parameter injection molding processing window.

[0040] The synchrotron radiation determination method for the injection molding window of crystalline plastics provided by the embodiments of the present invention can be used in combination with synchrotron radiation X-ray scattering experimental techniques to obtain methods for regulating product structures with different processing parameters during the injection molding process of polymer materials; by establishing the relationships between crystallinity-process parameters, crystal form content-process parameters, lamellar thickness-process parameters, crystallization time-process parameters, and orientation degree-process parameters, the optimal process for the required structure can be obtained. In this way, the present invention expands the application of X-rays in the field of injection molding, converts X-ray diffraction and scattering information into changes in the multi-scale structure of polymers during the injection molding process, and further obtains the evolution of the multi-scale structure of polymers and kinetic parameters under different processing technologies, realizing the online monitoring of the structure of polymer melts in the injection molding die and the efficient determination of the injection molding processing window, with strong versatility, high measurement accuracy, convenience and practicality. It can not only achieve intelligent injection molding, but also independently seek the best parameters for injection molding to achieve the required service performance.

[0041] It should be noted that the injection molding machine used in the experiments of the present invention is a Haitian electric injection molding machine, model VE600Ⅱ / 120h, with an injection capacity of 36 cm 3 ; The small-angle X-ray scattering (SAXS) / wide-angle X-ray diffraction (WAXD) combined system of the Shanghai Synchrotron Radiation Facility is installed in the industrial experimental station of the Shanghai Synchrotron Radiation Facility (SSRF, Shanghai, China). This experimental station has high-throughput characterization capabilities, an electron beam energy of 3.5 GeV, a high X-ray photon flux (>1013 phs / s), and the wavelength (λ) of the X-ray source is 0.1240 nm. The online characterization platform built is as Figure 2 shown, where Figure 2 (a) is a physical picture of an industrial-grade injection molding machine, Figure 2 (b) is a remote operation platform for controlling the operation of the injection molding machine and starting the X-ray characterization experiment. Figure 2(c-d) refers to the SAXS / WAXS detector used in this experiment. The polymer materials used in the examples include crystalline polymers such as PP, PE, PLA, PA6 and their blends / composites. The basic information of the materials is shown in Table 1.

[0042] Reference Figure 3 , the present invention provides a method for quickly determining the injection molding window of crystalline plastics based on synchrotron radiation X-ray technology, including the following contents:

[0043] Step 1: List the various influencing factors and test levels affecting polymer injection molding according to experience and relevant literature, and design a test plan using an orthogonal test table. Tables 2 to 5 show 5 factors and 4 levels, and the orthogonal experiment design is changed according to different materials and required performance indicators. Start the experiment according to the designed test plan, and use X-ray ultra-high-speed in-situ characterization technology to track the structural information of the polymer injection molding process under different process conditions.

[0044] Step 2: Obtain two-dimensional images of the melt wide-angle / small-angle scattering (WAXS / SAXS) signal intensity varying with time during the injection molding process under different process conditions through orthogonal experiments. After subtracting the air background, perform 360° one-dimensional integration on the two-dimensional images to obtain the scattering vector q value-scattering intensity curves at two scales of wide angle and small angle respectively, and obtain structural parameters such as crystallization time, crystallinity, orientation degree, and lamellar thickness through batch processing using the developed software.

[0045] Step 3: Draw a three-parameter processing window diagram: Establish the relationships of crystallinity-process parameters, crystal form content-process parameters, lamellar content-process parameters, crystallization time-process parameters, and orientation degree-process parameters, such as [crystallization time, injection rate, holding pressure], etc., and draw them into a double-coordinate diagram to obtain a three-parameter processing window, so as to obtain the optimal process for the required structure.

[0046] In some embodiments, the injection molded product is thicker (millimeter level) compared to other in-situ processing equipment (generally micron level). In addition, the general plastics targeted by this invention, such as polyolefins, crystallize very rapidly. Therefore, X-rays are required to have high throughput, high penetration (sample thickness is millimeter level) and millisecond-level time resolution ability.

[0047] In some embodiments, in the above step 1, the orthogonal experiment systematically studies the effects of molecular parameters and external field parameters on crystal structure and crystallization kinetics by implementing different injection molding process conditions on different polymer samples.

[0048] In some embodiments, the crystallization time Δt of the polymer in step 2 is calculated by the formula: ; where t 0 is the polymer start crystallization time, tpeak is the saturation moment of the diffraction intensity of the polymer crystal plane.

[0049] The growth of different crystal planes of the polymer is obtained from the 1D-WAXS curve, and the crystal plane with the strongest diffraction peak is selected to characterize the crystallization kinetics of the crystal. By establishing the relationship between time and the intensity of this crystal plane, a scattering intensity-time curve is plotted, and t is obtained by observing the curve 0 and t peak .

[0050] In some embodiments, the content of the polymer crystal form in the second step is obtained by peak fitting of 1D-WAXS (i.e., one-dimensional wide-angle X-ray scattering curve) to obtain the peak area A of each crystal plane hkl . The proportion of the sum of the peak areas of all crystal planes included in a certain crystal form to the peak areas of all crystal form crystal planes can represent the content of the polymer crystal form.

[0051] In some embodiments, the calculation method of the crystallinity in the second step is as follows: The 1D-WAXS curve of the injection molded product is subjected to peak fitting, and then the areas of the crystal peaks and the amorphous peaks in the sample are obtained. Finally, the total crystallinity Xc of the sample is calculated by the formula: , where, refers to the area of each crystal peak, represents the area of the amorphous peak.

[0052] In some embodiments, the crystal orientation degree in the second step is represented by the Herman orientation factor f H . f H is calculated by the following expression:

[0053]

[0054] where, refers to the orientation factor, and this factor is calculated by the following formula:

[0055]

[0056] Among them, is the angle between the normal of the given (hkl) crystal plane and the reference direction, is the diffraction intensity along the angle .

[0057] In some embodiments, the calculation of the lamellar thickness in the second step is based on an ideal two-phase lamellar microstructure model. The scattering vector-scattering intensity curve at the small angle scale is Fourier-transformed to obtain a one-dimensional electron density function . By analyzing the one-dimensional electron density function, the target structure parameter is extracted: the target structure parameter is the average thickness d of the crystal layer c , where the one-dimensional electron density function The expression is as follows:

[0058] ;

[0059] In the formula, represents the electron density distribution in the z direction, z represents the distance in the real space; q represents the small-angle scattering vector.

[0060] Table 1 Basic information of the selected materials in the experimental examples

[0061]

[0062] Table 2 HDPE orthogonal test factor level table

[0063]

[0064] Table 3 PP orthogonal test factor level table

[0065]

[0066] Table 4 PLA orthogonal test factor level table

[0067]

[0068] Table 5 PA6 orthogonal test factor level table

[0069]

[0070] Experiment 1. Determination of the crystallization time, referring to Figure 4 , the experiment includes the following steps:

[0071] 1) In this experimental design, the crystallization time is selected as the research index, and the mold temperature, melt temperature, injection rate, holding pressure, and holding time are selected as variables for orthogonal experimental design. Referring to relevant materials and combining with practical experience, Tables 2 to 5 show the value ranges of processing parameters for different materials, and 4 levels are selected for each factor. According to the designed test scheme, the test is started, and the X-ray ultra-high-speed in-situ characterization technology is used to track the structural information of the polymer injection molding process under different process conditions.

[0072] 2) Through the orthogonal experiment, a two-dimensional image of the wide-angle diffraction intensity of the polymer changing with time is obtained, such as Figure 4As shown. The air background is subtracted from the images in batches, and one-dimensional integration is continued to obtain the wide-angle scattering vector q value - scattering intensity curve. The diffraction intensity of the relatively higher crystal plane in the main crystal form of the polymer is selected to describe its crystallization kinetics characteristics, and the intensity change curve of this crystal plane over time is plotted. Therefore, the orthorhombic phase (110) of HDPE, the α (110) of PP, the α (110) of PLA, and the α (100) crystal plane of PA6 are selected. By defining the time interval from the start of crystal plane growth to the maximum equilibrium intensity of diffraction as the crystallization time (Δt) and using it as a characteristic parameter of processing efficiency.

[0073] 3) Establish the relationship between crystallization time and process parameters, such as [crystallization time, injection rate, holding pressure], etc. After plotting it into a double coordinate graph, a three-parameter processing window is obtained, so as to obtain the optimal process for the required structure.

[0074] The statistical results of crystallization time are shown in Table 6. The crystallization time of polymer materials under different processing conditions can be quickly determined, which helps to confirm the injection molding cycle time and guide the selection of mold opening time. In addition, it is found that the injection rate and holding pressure have a greater impact on the crystallization time of polymers. A three-parameter processing window graph of [crystallization time, injection rate, holding pressure] is plotted, which can conveniently determine the optimal processing conditions of some polymers during injection molding. As Figure 5 shown, the "light-colored area" represents the range of processing conditions where the polymer crystallizes slowly, and the "dark-colored area" represents the range of processing conditions where the polymer crystallizes quickly.

[0075] Generally speaking, a high holding pressure shortens the crystallization time and is beneficial to the crystal growth of rapidly crystallizing polymers. However, for the slowly crystallizing polylactic acid material, the pressure slows down the crystallization speed. In contrast, the injection speed has no obvious effect on the crystallization time. This result shows that the present invention helps to draw the processing window of injection molding in a high-throughput manner, obtain the quantitative solidification time of injection molded products in the mold cavity, guide the selection of mold opening time, improve processing efficiency, and has practicality and feasibility for determining the injection molding processing window of polymers.

[0076] Table 6 Results of orthogonal experiment indexes

[0077]

[0078] Experiment 2. Determination of crystallinity, orientation degree, and lamellar thickness. The experiment includes the following steps:

[0079] 1) In this experimental design, crystallinity, orientation degree, and lamellar thickness were selected as the research indicators, and mold temperature, melt temperature, injection rate, holding pressure, and holding time were selected as variables for orthogonal experimental design. Referring to relevant materials and combining with practical experience, Tables 2 to 5 show the value ranges of processing parameters for different materials, and 4 levels were selected for each factor. According to the designed test plan, the experiment was carried out, and the X-ray ultra-high-speed in-situ characterization technology was used to track the structural information of the polymer injection molding process under different process conditions.

[0080] 2) Two-dimensional images of the wide-angle / small-angle scattering intensity of the polymer changing with time were obtained through orthogonal experiments. The images were batch-subtracted from the air background, and then one-dimensional integration was continued to obtain the scattering vector q value - scattering intensity curves at two scales of wide-angle / small-angle respectively. Through batch processing with the developed software, structural parameters such as crystallinity, lamellar thickness, and orientation degree of each material under different processing parameters were obtained.

[0081] 3) The relationships between crystallinity - process parameters, lamellar thickness - process parameters, and orientation degree - process parameters were established, and after plotting them into double-coordinate graphs, a three-parameter processing window was obtained, thereby obtaining the optimal process for the required structure.

[0082] The experimental results are shown in Table 7. Through Table 7, the injection processing parameters required for the desired structure can be quickly determined, thereby realizing the regulation of the microstructure of the product. Taking polypropylene as an example, a microstructure processing window diagram was drawn, as Figure 6 shown. This diagram shows the highly oriented structure of polyolefin materials in injection molding, as well as the increase in crystallinity and lamellar thickness with the increase in holding pressure. In addition, Figure 7 a crystal form window diagram of polypropylene material was drawn, proving the feasibility of this method for polymer crystal form regulation.

[0083] Table 7 Results of orthogonal experiment indicators

[0084]

[0085] To sum up, a synchrotron radiation determination method for the injection window of crystalline plastics provided by the present invention can realize the online monitoring of the structure of polymer melt in the injection mold and the efficient determination of the injection processing window. It has strong generality, high measurement accuracy, is convenient and practical, can guide the selection of mold opening time and the control of microstructure, and is of great significance for improving the quality of injection products and the efficiency of injection processing. Moreover, this method is widely applicable to crystalline polymers and has high value in industry.

[0086] The above is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and scope of the present invention are included in the protection scope of the present invention.

[0087] It should be understood that the "one embodiment" or "an embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present invention. Therefore, the "in one embodiment" or "in an embodiment" that appears throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present invention, the magnitude of the serial numbers of the above processes does not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention. The serial numbers of the embodiments of the present invention above are only for description and do not represent the advantages or disadvantages of the embodiments.

[0088] It should be noted that in this text, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the element. In several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored, or not executed.

[0089] As described above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for determining a crystalline plastic injection window by synchrotron radiation, characterized in that: S1. Obtaining experimental injection molding process parameters and experimental crystal structure parameters of the plastic to be injected, and designing an orthogonal experiment; S2. Applying the process parameters to an injection molding experiment, and using a wide-angle / small-angle X-ray scattering detector in conjunction with the experimental process to obtain two-dimensional scattering image data of the melt at the center of the injection mold in real time; S3, sequentially performing data processing and integration processing on the two-dimensional scattering image data to obtain scattering vector-scattering intensity curves of the plastic to be injected at wide angles and small angles; and obtaining crystal structure parameters of the plastic to be injected based on the scattering vector-scattering intensity curves; the structure parameters include crystallization time, crystallinity, orientation degree and lamella thickness; S4. Correlation analysis is performed on the experimental injection molding process parameters and the crystal structure parameters to establish the relationships between crystallinity-process parameters, crystal content-process parameters, lamella thickness-process parameters, crystallization time-process parameters, and orientation degree-process parameters; and multiple relationships are plotted into a dual coordinate diagram to obtain a three-parameter injection molding processing window.

2. The method according to claim 1, characterized in that When establishing the relationship between crystallization time and process parameters, the crystallization time Δt of the polymer is calculated by the following formula: ; where t0 is the moment when the polymer begins to crystallize, t peak is the moment when the diffraction intensity of the polymer crystal face is saturated; the growth of different crystal faces of the polymer is obtained through the one-dimensional wide-angle X-ray scattering curve, and the crystal face with the strongest diffraction peak is selected to characterize the crystal crystallization dynamics; by establishing the relationship between time and crystal face intensity, the scattering intensity-time curve is drawn, and t0 and t peak .

3. The method according to claim 1, characterized in that When establishing the relationship between crystal content and process parameters, the crystal content of the polymer is expressed as the ratio of the sum of all crystal face peak areas contained in one crystal form to the crystal face peak areas of all crystal forms. The peak area A of each crystal face is obtained by performing peak fitting on the one-dimensional wide-angle X-ray scattering curve. hkl .

4. The method according to claim 3, characterized in that The area of ​​each crystalline peak and amorphous peak is obtained through the one-dimensional wide-angle X-ray scattering curve, and the total crystallinity Xc of the polymer is calculated by the following formula: ； In the formula, Refers to the area of ​​each crystal peak, Represents the amorphous peak area.

5. The method according to claim 1, characterized in that When establishing the relationship between orientation degree and process parameters, the orientation degree f H The calculation is done by the following formula: ； In the formula, It refers to the orientation factor, which is calculated by the following formula: ； In the formula, is the angle between the normal to a given (hkl) crystal plane and the reference direction, Is along the angle The diffraction intensity.

6. The method according to claim 1, characterized in that When establishing the relationship between the thickness of the lamellae and the process parameters, the calculation of the thickness of the lamellae is based on an ideal two-phase layered microstructure model, and the scattering vector-scattering intensity curve at a small angle scale is Fourier transformed to obtain a one-dimensional electron cloud density function. , extract the target structural parameters by analyzing the one-dimensional electron cloud density function: the target structural parameter is the average thickness of the crystal layer d c , where the one-dimensional electron cloud density function The expression is as follows: ； In the formula, represents the electron density distribution in the z direction, z represents the distance in real space; q represents the small-angle scattering vector.

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