Synchrotron radiation determination method for crystalline plastic injection molding window

Abstract

The invention provides a crystalline plastic injection molding window synchrotron radiation determination method, relates to the field of crystalline plastic injection molding on-line detection, and can be combined with a synchrotron radiation X-ray scattering experiment technology to obtain different processing parameters in a high polymer material injection molding process to regulate and control a product structure. The optimal process for the required structure is obtained by respectively establishing the relationship between the crystallinity, the crystal form content, the lamellar crystal thickness, the crystallization time and the orientation degree and the process parameters. Thus, polymer multi-scale structure evolution and kinetic parameters under different processing technologies are obtained, online monitoring of a polymer melt structure in an injection molding mold and efficient determination of an injection molding processing window are achieved, the synchrotron radiation technology is applied to monitoring of three-dimensional part processing for the first time, universality is high, measurement precision is high, and convenience and practicability are achieved; and optimal parameters of injection molding processing can be autonomously sought, so that intelligent injection molding is realized, and the required service performance is achieved.

Description

Technical Field

[0001] The invention relates to the field of online detection of crystalline plastic injection molding, and relates to but is not limited to a method for determining a crystalline plastic injection molding window by synchronous radiation. Background Art

[0002] In the field of polymer injection molding, it is crucial to accurately control processing parameters to optimize product performance and processing efficiency. Traditional injection molding processing methods often rely on empirical settings, focusing more on the stability of the product production process and the consistency of product quality, and lacking real-time monitoring and quantitative analysis of the flow, cooling and crystallization process of the polymer melt in the mold. This results in the determination of the processing window often requiring a lot of trial and error, which is not only time-consuming and labor-intensive, 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 realize the real-time and quantitative analysis of the microstructure of polymer melts, so as to more accurately determine the injection molding process window and improve product quality and production efficiency.

[0004] However, during the injection molding process, polymer structures have multi-scale characteristics and evolve rapidly within seconds under complex thermomechanical environments, so it is difficult to obtain the dynamic characteristics of structure formation through characterization methods such as in situ Raman microscopy, in situ optical microscopy, and neutron scattering. Synchrotron radiation X-ray diffraction (scattering) technology has high throughput, high penetration (sample thickness is millimeter level) and millisecond time resolution, and has been used for in situ characterization of rotational rheology and other laboratory small instrument experiments. Chinese patent CN 107063889 B provides a creep stretching device combined with X-ray scattering, but this device serves for simple two-dimensional product (film) molding. How to combine synchrotron radiation X-ray in situ characterization with complex three-dimensional product molding instrument installation is still a challenge. The space 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 must be solved first. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes a method for determining the injection molding window of crystalline plastics by synchrotron radiation. Without destroying the injection molded samples, the microstructural information such as crystallization dynamics, evolution of polymorphs, growth and orientation of polymer lamellae of semi-crystalline polymers during the injection molding process is obtained, and the polymer injection molding processing window is determined efficiently.

[0006] The technical method of the embodiment of the present invention is implemented as follows: In a first aspect, an embodiment of the present invention provides a method for determining a crystalline plastic injection window by synchrotron radiation, the method comprising: 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.

[0007] In some embodiments, 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 .

[0008] In some embodiments, 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, and 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 .

[0009] In some embodiments, the area of ​​each crystalline peak and amorphous peak is obtained by 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.

[0010] In some embodiments, when establishing the relationship between orientation degree and process parameters, the orientation degree f H The calculation is done by the following formula:

[0011] In the formula, It refers to the orientation factor, which is calculated by the following formula:

[0012] 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.

[0013] In some embodiments, 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.

[0014] The synchrotron radiation determination method for the crystalline plastic injection molding window provided by the embodiment of the present invention can be used in conjunction with the synchrotron radiation X-ray scattering experimental technology to obtain a method for regulating the product structure by different processing parameters in the injection molding process of polymer materials; by establishing the relationship between crystallinity-process parameters, crystal content-process parameters, lamella thickness-process parameters, crystallization time-process parameters, and orientation degree-process parameters, the optimal process for the required structure is obtained. In this way, the present invention converts X-ray diffraction and scattering information into changes in the multi-scale structure of the polymer during the injection molding process, and then obtains the multi-scale structure evolution and kinetic parameters of the polymer under different processing technologies, realizing the online monitoring of the polymer melt structure in the injection molding mold and the efficient determination of the injection molding process window, with strong versatility, high measurement accuracy, convenience and practicality, breaking the black box mode on the traditional injection molding structure. In addition, the present invention extends synchrotron radiation technology from laboratory static analysis to industrial-grade dynamic processing monitoring, directly serving the optimization of injection molding process; and integrates multiple structural parameters and real-time correlations between dynamic parameters and process parameters, breaking through the limitations of traditional single variable optimization; and drives the automatic adjustment of injection molding machine parameters through structural data fed back by synchrotron radiation, forming a "monitoring-analysis-control" closed-loop system to achieve intelligent injection molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic flow chart of a method for determining a crystalline plastic injection molding window by synchrotron radiation provided in an embodiment of the present invention; Figure 2 (a) is a physical picture of an industrial-grade injection molding machine provided by an embodiment of the present invention, Figure 2 (b) is a remote operation platform provided by an embodiment of the present invention, Figure 2 (cd) is the experimental combined SAXS / WAXS detector provided in the embodiment of the present invention; Figure 3 It is a schematic flow chart of a method for determining a polymer processing window in injection molding provided by an embodiment of the present invention; Figure 4 It is a schematic diagram of a process flow for determining a polymer crystallization time processing window in injection molding provided by an embodiment of the present invention; Figure 5 (a) is a diagram of the polyethylene crystallization time processing window provided by an embodiment of the present invention, Figure 5 (b) is a diagram of the crystallization time processing window of polypropylene α crystals provided by an embodiment of the present invention, Figure 5 (c) refers to the polylactic acid crystallization time processing window provided by the embodiment of the present invention, Figure 5 (d) refers to the nylon 6 crystallization time processing window provided in the embodiment of the present invention; Figure 6 (a) is the crystallinity injection molding processing window provided by an 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 a crystal orientation injection molding processing window provided by an embodiment of the present invention; Figure 7 is the polypropylene polymorph distribution processing window provided by the embodiment of the present invention, Figure 7 (ac) refer to the crystal content distribution windows of polypropylene α crystal, β crystal and γ crystal at different injection rates and holding pressures, respectively. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present invention. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0017] In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments, but it is understood that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may 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 those commonly understood by those skilled in the art to which the embodiments of the present invention pertain. 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.

[0018] The embodiment of the present invention provides a method for determining a crystalline plastic injection molding window by synchrotron radiation, see Figure 1 , Figure 1 is a flow chart of a method for determining a crystalline plastic injection molding window by synchrotron radiation provided by an embodiment of the present invention, which is combined with Figure 1 The steps shown are explained.

[0019] Step S1, obtaining experimental injection molding process parameters and experimental crystal structure parameters of the plastic to be injected, and designing an orthogonal experiment.

[0020] Step 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; Step 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 based on the scattering vector-scattering intensity curves, obtaining crystal structure parameters of the plastic to be injected; the structure parameters include crystallization time, crystallinity, orientation degree and lamella thickness; Step S4, performing correlation analysis on the experimental injection molding process parameters and the crystal structure parameters, establishing the relationship between crystallinity-process parameters, crystal content-process parameters, lamella thickness-process parameters, crystallization time-process parameters, and orientation degree-process parameters; and plotting the multiple relationships into a dual coordinate diagram to obtain a three-parameter injection molding processing window.

[0021] The synchronous radiation determination method of the crystalline plastic injection molding window provided by the embodiment of the present invention can be used in conjunction with the synchronous radiation X-ray scattering experimental technology to obtain the method of regulating the product structure of different processing parameters in the injection molding process of polymer materials; by establishing the relationship between crystallinity-process parameters, crystal content-process parameters, lamella thickness-process parameters, crystallization time-process parameters, and orientation degree-process parameters, the optimal process for the required structure is 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 then obtains the multi-scale structural evolution and kinetic parameters of polymers under different processing technologies, realizes the online monitoring of the polymer melt structure in the injection molding mold, and the efficient determination of the injection molding process window, with strong versatility, high measurement accuracy, convenience and practicality, not only can intelligent injection molding be realized, but also the optimal parameters for injection molding can be independently sought, thereby achieving the required service performance.

[0022] It should be noted that the injection molding machine used in the experiment of the present invention is a Haitian electric injection molding machine, model VE600Ⅱ / 120h, with an injection capacity of 36 cm 3 ; Shanghai Light Source Small Angle X-ray Scattering (SAXS) / Wide Angle X-ray Diffraction (WAXD) combined system, installed in the industrial experimental station of Shanghai Synchrotron Radiation Facility (SSRF, Shanghai, China), which has high-throughput characterization capabilities, electron beam energy of 3.5 GeV, high X-ray photon flux (>1013 phs / s), and X-ray source wavelength (λ) of 0.1240 nm. The online characterization platform built is as follows Figure 2 As shown, Figure 2 (a) is a physical picture of an industrial-grade injection molding machine. Figure 2 (b) is the remote operation platform, which is used to control the operation of the injection molding machine and start the X-ray characterization experiment. Figure 2 (cd) refers to the SAXS / WAXS detector used in the experiment. The polymer materials used in the examples are crystalline polymers such as PP, PE, PLA, PA6 and their blends / composites. The basic information of the materials is shown in Table 1.

[0023] refer to Figure 3 The present invention provides a method for quickly determining a crystalline plastic injection molding processing window based on synchrotron radiation X-ray technology, comprising the following contents: Step 1: List the various influencing factors and test levels that affect polymer injection molding based on experience and relevant literature, and use the orthogonal test table to design the test plan. Tables 2 to 5 show 5 factors and 4 levels. Change the orthogonal experimental design 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.

[0024] Step 2. Through orthogonal experiments, a two-dimensional image of the wide-angle / small-angle scattering (WAXS / SAXS) signal intensity of the melt changing with time during the injection molding process under different process conditions is obtained. After deducting the air background, a 360° one-dimensional integration is performed on the two-dimensional image to obtain the scattering vector q value-scattering intensity curves at wide-angle and small-angle scales, respectively. The structural parameters such as crystallization time, crystallinity, orientation degree, and lamellar thickness are obtained by batch processing through the developed software.

[0025] Step 3. Draw a three-parameter processing window diagram: establish the relationship between crystallinity-process parameters, crystal content-process parameters, lamellar content-process parameters, crystallization time-process parameters, orientation degree-process parameters, such as [crystallization time, injection rate, holding pressure], etc., and draw it into a double coordinate diagram to obtain the three-parameter processing window, so as to obtain the best process for the required structure.

[0026] In some embodiments, the injection molded product is thicker (millimeter level) than other in-situ processing equipment (generally micrometer level). In addition, the general plastics targeted by the invention, such as polyolefins, crystallize very quickly. Therefore, X-rays are required to have high throughput, high penetration (sample thickness is millimeter level) and millisecond time resolution.

[0027] In some embodiments, the orthogonal experiment in step 1 above systematically studies the effects of molecular parameters and external field parameters on crystal structure and crystallization dynamics by applying different injection molding process conditions to different polymer samples.

[0028] In some embodiments, the polymer crystallization time Δt in step 2 is calculated by the formula: ; Where t0 is the time when the polymer starts to crystallize, t peak is the moment when the diffraction intensity of the polymer crystal surface reaches saturation.

[0029] The growth of different crystal faces of the polymer is obtained through the 1D-WAXS curve, and the crystal face with the strongest diffraction peak is selected to characterize the crystallization dynamics of the crystal. By establishing the relationship between time and the intensity of the crystal face, the scattering intensity-time curve is drawn, and t0 and t peak .

[0030] In some embodiments, the polymer crystal content in step 2 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 face. hkl The ratio of the sum of the peak areas of all crystal faces contained in a certain crystal form to the peak areas of all crystal faces of the crystal form can represent the crystal content of the polymer.

[0031] In some embodiments, the crystallinity calculation method in step 2 is as follows: the 1D-WAXS curve of the injection molded product is peak-fitted to obtain the area of ​​each crystalline peak and amorphous peak in the sample, and finally the total crystallinity Xc of the sample is calculated by the formula: , where Refers to the area of ​​each crystal peak, Represents the amorphous peak area.

[0032] In some embodiments, the crystal orientation degree in step 2 is measured by the Hermann orientation factor f H To indicate that f H Calculated by the following expression:

[0033] In the formula, It refers to the orientation factor, which is calculated by the following formula:

[0034] in, is the angle between the normal to a given (hkl) crystal plane and the reference direction, Is along the angle The diffraction intensity.

[0035] In some embodiments, the calculation of the platelet thickness in step 2 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.

[0036] Table 1 Basic information of materials used in the experimental examples

[0037] Table 2 HDPE orthogonal test factor level table

[0038] Table 3 PP orthogonal test factor level table

[0039] Table 4 PLA orthogonal test factor level table

[0040] Table 5 PA6 orthogonal test factor level table

[0041] Experiment 1: Determination of crystallization time, reference Figure 4 ,The experiment includes the following steps: 1) This experimental design uses crystallization time as the research indicator, and selects mold temperature, melt temperature, injection rate, holding pressure and holding time as variables for orthogonal experimental design. Referring to relevant materials and combining practical experience, Tables 2 to 5 show the range of processing parameters for different materials, and 4 levels are selected for each factor. According to the designed experimental plan, the experiment was started, and the structural information of the polymer injection molding process under different process conditions was tracked using X-ray ultra-high-speed in-situ characterization technology.

[0042] 2) Through orthogonal experiments, a two-dimensional image of the wide-angle diffraction intensity of the polymer is obtained as a function of time, such as Figure 4 As shown. The air background is subtracted from the image in batches, and one-dimensional integration is continued to obtain the wide-angle scattering vector q value-scattering intensity curve. The relatively high crystal plane diffraction intensity in the main crystal form of the polymer is selected to describe its crystallization dynamics characteristics, and the intensity change curve of the crystal plane over time is plotted. Therefore, the orthorhombic phase (110) of HDPE, α (110) of PP, α (110) of PLA, and α (100) of PA6 are selected. The time interval from the start of crystal plane growth to the maximum equilibrium intensity of diffraction is defined as the crystallization time (Δt) and is used as a characteristic parameter of processing efficiency.

[0043] 3) Establish the relationship between crystallization time and process parameters, such as [crystallization time, injection rate, holding pressure], etc., and plot it into a double coordinate graph to obtain a three-parameter processing window, so as to obtain the optimal process for the required structure.

[0044] The statistical results of crystallization time are shown in Table 6, which can quickly determine the crystallization time of polymer materials under different processing conditions, thereby helping to confirm the injection molding cycle time and guiding the selection of mold opening time. In addition, it was found that the injection rate and holding pressure have a greater impact on the crystallization time of the polymer. A three-parameter processing window diagram of [crystallization time, injection rate, holding pressure] was drawn, which can easily determine the optimal processing conditions for certain polymers during the injection molding process. Figure 5 As shown, the "light area" represents the range of processing conditions where the polymer crystallizes more slowly, and the "dark area" represents the range of processing conditions where the polymer crystallizes more quickly.

[0045] Generally speaking, high holding pressure shortens the crystallization time and is conducive to the crystal growth of fast-crystallizing polymers, while for slower-crystallizing polylactic acid materials, pressure slows down the crystallization rate. In contrast, injection speed has no significant effect on crystallization time. This result shows that the present invention helps to draw the processing window of injection molding in a high-throughput manner, obtain a quantitative solidification time of the injection molded product in the mold cavity, guide the selection of mold opening time, and improve processing efficiency. It is practical and feasible for determining the polymer injection molding processing window.

[0046] Table 6 Orthogonal experiment index results

[0047] Experiment 2: Determination of crystallinity, orientation and lamella thickness. The experiment includes the following steps: 1) This experimental design uses crystallinity, orientation, and lamellar thickness as research indicators, and selects mold temperature, melt temperature, injection rate, holding pressure, and holding time as variables for orthogonal experimental design. Referring to relevant materials and combining practical experience, Tables 2 to 5 show the range of processing parameters for different materials, and 4 levels are selected for each factor. According to the designed experimental plan, the experiment was started, and the structural information of the polymer injection molding process under different process conditions was tracked using X-ray ultra-high-speed in-situ characterization technology.

[0048] 2) Through orthogonal experiments, a two-dimensional image of the wide-angle / small-angle scattering intensity of the polymer is obtained over time. The air background is subtracted from the image in batches, and one-dimensional integration is performed to obtain the scattering vector q value-scattering intensity curve at two scales of wide angle / small angle. The developed software batch processing obtains the structural parameters such as crystallinity, lamella thickness, and orientation degree of each material under different processing parameters.

[0049] 3) Establish the relationship between crystallinity and process parameters, lamella thickness and process parameters, and orientation degree and process parameters, and plot them into a double coordinate diagram to obtain a three-parameter processing window, so as to obtain the best process for the required structure.

[0050] The experimental results are shown in Table 7. Through Table 7, the injection molding processing parameters of the required structure can be quickly determined, thereby realizing the microstructure regulation of the product. Taking polypropylene as an example, a microstructure processing window diagram is drawn, such as Figure 6 As shown in the figure, the highly oriented structure of polyolefin materials in injection molding is demonstrated, and the increase in holding pressure can improve crystallinity and lamella thickness. In addition, Figure 7A crystal window diagram of polypropylene material was drawn to prove the feasibility of this method for regulating the crystal form of polymers.

[0051] Table 7 Orthogonal experiment index results

[0052] In summary, the method for determining the injection window of crystalline plastic by synchrotron radiation provided by the present invention can realize the online monitoring of the polymer melt structure in the injection molding mold and the efficient determination of the injection molding process window. It has strong versatility, high measurement accuracy, convenience and practicality, and can guide the selection of mold opening time and the control of microstructure. It is of great significance to improving the quality of injection products and improving the efficiency of injection molding. The method is widely applicable to crystalline polymers and has high value in industry.

[0053] The above description is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement and improvement made within the spirit and scope of the present invention are included in the protection scope of the present invention.

[0054] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present invention. Therefore, "in one embodiment" or "in an embodiment" appearing 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 size of the serial number of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention. The serial numbers of the above-mentioned embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments.

[0055] It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of further restrictions, an element defined by the statement "comprises one..." does not exclude the presence of other identical elements 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 merely schematic. For example, the division of the units is only a logical function division. 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.

[0056] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on 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, and 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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