Method for detecting microstructure of polypropylene / elastomer composite material

Abstract

The invention provides a detection method of a microstructure of a polypropylene / elastomer composite material. The detection method comprises the following steps: dispersing and mixing titanium dioxide nanoparticles and polypropylene to prepare titanium dioxide / polypropylene master batch; carrying out melt blending on the titanium dioxide / polypropylene master batch to prepare a mixture; mixing the mixture with an elastomer to prepare a composite material; and carrying out hot-pressing vulcanization on the composite material to prepare a sample to be detected, and observing the microstructure of the sample to be detected. According to the detection method, post-treatment dyeing is not needed, the microstructure can be observed in real time in the preparation stage of the composite material, and the detection method has the advantages of being rapid, efficient, low in cost and the like.

Description

Technical Field

[0001] This application relates to the field of polymer composite materials technology, and in particular to a method for detecting the microstructure of polypropylene / elastomer composite materials. Background Technology

[0002] Polypropylene / elastomer composites are lightweight and highly tough, making them widely used in automotive, packaging, and electronic devices. The properties of polypropylene / elastomer composites are closely related to their microstructure, particularly the distribution of crystalline and amorphous regions in polypropylene, the dispersion state of the elastomer phase, and the bonding strength at the interface between the two phases. Crystalline regions impart rigidity, amorphous regions provide toughness, and the interfacial bonding state directly affects stress transfer efficiency and the overall impact resistance of the material. Therefore, accurately characterizing the microstructure of polypropylene / elastomer composites is crucial for optimizing their properties.

[0003] Traditional techniques for characterizing the microstructure of polymer composites include X-ray diffraction (XRD) and differential scanning calorimetry (DSC). However, these methods cannot visually display the spatial distribution of crystalline and amorphous regions. For example, XRD can only calculate crystallinity through diffraction peaks and cannot distinguish the microscopic differences between local crystalline and amorphous regions.

[0004] Meanwhile, traditional staining techniques suffer from drawbacks such as poor stability, complex operation, and complicated post-processing staining steps, making it difficult to meet the needs of rapid detection and online quality control in industrial production. For example, when using iodine vapor staining combined with optical microscopy to observe polypropylene crystalline regions, the volatility of iodine causes the contrast to decay over time, thus affecting the accuracy of characterization, and it is not compatible with scanning electron microscopy (SEM) analysis. When using fluorescent dyes to label amorphous regions, the fluorescence signal is easily interfered with by ambient light, and the distinction between the fluorescent dye and the elastomer phase is insufficient.

[0005] Therefore, how to accurately characterize the distribution of polypropylene crystalline and amorphous regions, the dispersion state of the elastomer phase, and the interface between the two phases has become a problem to be solved. Summary of the Invention

[0006] Based on this, one or more embodiments of this application provide an efficient method for detecting the microstructure of polypropylene / elastomer composite materials.

[0007] According to one aspect of the embodiments of this application, a method for detecting the microstructure of a polypropylene / elastomer composite material is provided, comprising the following steps:

[0008] Titanium dioxide nanoparticles were dispersed and mixed with polypropylene to prepare titanium dioxide / polypropylene masterbatch;

[0009] The titanium dioxide / polypropylene masterbatch is melt-blended to prepare a mixture;

[0010] The mixture is then combined with an elastomer to prepare a composite material.

[0011] The composite material was subjected to hot-press vulcanization to prepare a test sample, and the microstructure of the test sample was observed.

[0012] In some embodiments, the mass ratio of the polypropylene to the elastomer is (5~7):(3~5).

[0013] In some embodiments, before dispersing and mixing the titanium dioxide nanoparticles with polypropylene, the following step is further included: modifying the titanium dioxide nanoparticles with a silane coupling agent.

[0014] Optionally, the mass fraction of the silane coupling agent is 1% to 3% based on the total mass of the titanium dioxide nanoparticles.

[0015] In some embodiments, the detection method satisfies at least one of the following characteristics:

[0016] (1) The particle size of the titanium dioxide nanoparticles is 10 nm to 15 nm;

[0017] (2) The mass fraction of the titanium dioxide nanoparticles is 0.05% to 1% based on the total mass of the titanium dioxide nanoparticles and the polypropylene.

[0018] In some embodiments, the thickness of the sample to be tested is 0.1 mm to 1 mm.

[0019] In some embodiments, the microstructure of the sample under test is observed using a scanning electron microscope and / or a polarizing microscope.

[0020] In some embodiments, the detection method satisfies at least one of the following characteristics:

[0021] (1) When observing the microstructure of the sample to be tested, the method includes scanning electron microscopy, wherein the scanning electron microscopy mode is backscattered electron mode and the accelerating voltage is 5kV~15kV;

[0022] (2) When the method for observing the microstructure of the sample to be tested includes a polarizing microscope, the magnification of the polarizing microscope is 200 to 1000 times.

[0023] In some embodiments, the titanium dioxide nanoparticles are dispersed and mixed with the polypropylene by twin-screw extrusion;

[0024] Optionally, the processing temperature of the twin-screw extrusion is 180℃~220℃.

[0025] In some embodiments, the temperature of the feeding section of the twin-screw extruder is 180°C to 190°C, the temperature of the melting section of the twin-screw extruder is 200°C to 210°C, and the temperature of the homogenization section of the twin-screw extruder is 210°C to 220°C.

[0026] In some embodiments, the detection method further includes the step of detecting the uniformity of titanium dioxide distribution in the sample to be tested.

[0027] Compared with traditional technologies, this application has the following advantages:

[0028] This application disperses titanium dioxide nanoparticles in polypropylene. Based on the compatibility differences between polypropylene and elastomers, titanium dioxide selectively accumulates in the polypropylene phase, creating a macroscopic contrast where "polypropylene appears white, while the elastomer is transparent," thus enabling the differentiation between the polypropylene and elastomer phases. Simultaneously, based on the differential distribution of titanium dioxide in crystalline and amorphous regions, simultaneous analysis of the crystalline, amorphous, and phase interfaces is possible. The detection method in this application requires no post-processing staining, allows real-time observation of the microstructure during the composite material preparation stage, and offers advantages such as speed, efficiency, and low cost. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the specific embodiments of this application, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0030] Figure 1 This is a SEM image of the polypropylene / elastomer composite material in Example 1 of this application;

[0031] Figure 2 This is a stained polarized light image of the polypropylene / elastomer composite material in Example 1 of this application;

[0032] Figure 3 This is an unpolarized light image of the polypropylene / elastomer composite material in Example 1 of this application;

[0033] Figure 4 SEM image of the polypropylene / elastomer composite material in Comparative Example 1 of this application;

[0034] Figure 5This is a stained polarized light image of the polypropylene / elastomer composite material in Comparative Example 1 of this application;

[0035] Figure 6 This is an unpolarized light image of the polypropylene / elastomer composite material in Comparative Example 1 of this application. Detailed Implementation

[0036] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in this application are commercially available or can be prepared by existing methods.

[0038] The terms "and / or," "or / and," and "and / or" as used herein include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND," and also undoubtedly includes technical solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0039] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0040] The terms “combinations of,” “any combination of,” and “any combination of” used in this article include all suitable combinations of any two or more of the listed items.

[0041] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0042] In this document, terms such as “preferred,” “better,” “more suitable,” and “ideal” are merely used to describe implementation methods or examples that achieve better results, and should be understood not to limit the scope of protection of this application.

[0043] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0044] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0045] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0046] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0047] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0048] Some embodiments of this application provide a method for detecting the microstructure of polypropylene / elastomer composite materials, comprising the following steps:

[0049] S1. Titanium dioxide nanoparticles are dispersed and mixed with polypropylene to prepare titanium dioxide / polypropylene masterbatch;

[0050] S2. The titanium dioxide / polypropylene masterbatch is melt-blended to prepare a mixture; the mixture is then mixed with an elastomer to prepare a composite material.

[0051] S3. Hot-press vulcanize the composite material to prepare the test sample and observe the microstructure of the test sample.

[0052] This application disperses titanium dioxide nanoparticles in polypropylene. Based on the compatibility difference between polypropylene and elastomer, titanium dioxide is selectively enriched in the polypropylene phase, forming a macroscopic contrast of "polypropylene turning white and elastomer becoming transparent", thereby enabling the distinction between the polypropylene phase and the elastomer phase. At the same time, based on the differential distribution of titanium dioxide in crystalline and amorphous regions, simultaneous analysis of crystalline regions, amorphous regions and phase interfaces can be achieved.

[0053] In some embodiments, the mass ratio of polypropylene to elastomer is (5~7):(3~5).

[0054] As an example, the mass ratio of polypropylene to elastomer can be 5:5, 6:4, 7:3, or any value within the range of any two of the above ratios.

[0055] In some specific embodiments, the elastomer includes one or more of ethylene-propylene-diene monomer rubber (EPDM), propylene-based elastomer (PBE), and ethylene-olefin copolymer (EOC).

[0056] In some embodiments, before dispersing and mixing the titanium dioxide nanoparticles with polypropylene, the following step is further included: modifying the titanium dioxide nanoparticles with a silane coupling agent.

[0057] It is understandable that modifying titanium dioxide nanoparticles with silane coupling agents can further improve the dispersibility of titanium dioxide nanoparticles in polypropylene.

[0058] In some specific embodiments, the mass fraction of the silane coupling agent is 1% to 3% based on the total mass of the titanium dioxide nanoparticles.

[0059] As an example, based on the total mass of titanium dioxide nanoparticles, the mass fraction of the silane coupling agent can be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, or any value within the range formed by any two of the above points.

[0060] In some of these embodiments, the titanium dioxide nanoparticles have a particle size of 10 nm to 15 nm.

[0061] As an example, the particle size of titanium dioxide nanoparticles can be 10nm, 10.5nm, 11nm, 11.5nm, 12nm, 12.5nm, 13nm, 13.5nm, 14nm, 14.5nm, 15nm, or any value within the range formed by any two of the above values.

[0062] In some embodiments, the mass fraction of titanium dioxide nanoparticles is 0.05% to 1% based on the total mass of titanium dioxide nanoparticles and polypropylene.

[0063] As an example, the mass fraction of titanium dioxide nanoparticles can be 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any value within the range of any two of the above points, based on the total mass of titanium dioxide nanoparticles and polypropylene.

[0064] Understandably, if the mass fraction of titanium dioxide nanoparticles exceeds 1%, although it can help improve the dyeing effect, it may cause titanium dioxide agglomeration and affect the arrangement of crystalline and amorphous regions, which is not conducive to the analysis of the structure and distribution of polypropylene / elastomer.

[0065] In some embodiments, the thickness of the sample to be tested is 0.1 mm to 1 mm.

[0066] As an example, the thickness of the sample to be tested can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, or any value within the range formed by any two of the above point values.

[0067] In some embodiments, scanning electron microscopy and / or polarizing microscopy are used to observe the microstructure of the sample under test.

[0068] In some specific embodiments, before observing the microstructure of the sample under test using a scanning electron microscope, the following steps are also included: performing brittle fracture treatment and etching treatment on the sample under test.

[0069] Optionally, liquid nitrogen can be used to induce brittle fracture in the sample to be tested.

[0070] Understandably, when observing the brittle fracture surface of a sample using a scanning electron microscope (SEM), titanium dioxide selectively accumulates in the polypropylene phase, causing the polypropylene phase to appear whitish (high-brightness area), while the elastomer phase appears transparent (low-brightness area). Therefore, SEM can quickly distinguish the polypropylene and elastomer phases in polypropylene / elastomer composites. The polypropylene phase determines rigidity, heat resistance, and processing stability; the elastomer phase acts as a performance modifier, dominating toughness, elasticity, and low-temperature properties. Through interfacial compatibility, morphology control, and functional modification, the synergistic optimization of the properties of both phases can be achieved, meeting the comprehensive performance requirements of materials in various fields.

[0071] Meanwhile, the denser molecular chains in crystalline regions result in lower titanium dioxide dispersion compared to amorphous regions. Therefore, the dispersion of titanium dioxide can be used to further distinguish between crystalline (low dispersion) and amorphous (high dispersion) regions. During the preparation of composite materials, the distribution information of crystalline and amorphous regions allows for the targeted optimization of the composite material's rigidity, toughness, and heat resistance. Furthermore, the ratio of crystalline to amorphous regions enables the optimization of temperature, shear rate, and formulation, thereby improving the overall performance of the composite material.

[0072] It should be noted that when observing the sample under test using a scanning electron microscope, the thickness of the sample under test is 1 mm; when observing the sample under test using a polarizing microscope, the thickness of the sample under test is 0.1 mm.

[0073] In some embodiments, the scanning electron microscope is in backscattered electron mode, and the accelerating voltage is 5kV~15kV.

[0074] As an example, the accelerating voltage of a scanning electron microscope can be 5kV, 6kV, 7kV, 8kV, 9kV, 10kV, 11kV, 12kV, 13kV, 14kV, 15kV, or any value within the range formed by any two of the above points.

[0075] In some embodiments, the polarizing microscope has a magnification of 200 to 1000 times.

[0076] As an example, the magnification of a polarizing microscope can be 200x, 300x, 400x, 500x, 600x, 700x, 800x, 900x, 1000x, or any value within the range formed by any two of the above point values.

[0077] Understandably, the crystalline regions of polypropylene exhibit colored interference fringes and bright spots due to birefringence, while the amorphous regions and elastomer phases of polypropylene present a uniform dark field. Combining this with a polarizing microscope allows for further differentiation and characterization of the polypropylene phase, elastomer phase, and the crystalline and amorphous regions of polypropylene.

[0078] Titanium dioxide is chemically stable, with no volatilization or photodegradation issues, and is compatible with SEM and optical microscopes, improving upon the stability deficiencies of traditional staining techniques (such as iodine and fluorescent dyes). Furthermore, nanoparticles can significantly enhance the imaging clarity of amorphous regions and phase interfaces, and their cost is significantly lower than that of fluorescent dyes.

[0079] In some embodiments, titanium dioxide nanoparticles are dispersed and mixed with polypropylene by twin-screw extrusion.

[0080] In some specific embodiments, the processing temperature of twin-screw extrusion is 180°C to 220°C.

[0081] As an example, the processing temperature of twin-screw extrusion can be 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 220℃, or any value within the range formed by any two of the above points.

[0082] In some embodiments, the temperature of the feeding section of the twin-screw extruder is 180°C to 190°C, the temperature of the melting section of the twin-screw extruder is 200°C to 210°C, and the temperature of the homogenization section of the twin-screw extruder is 210°C to 220°C.

[0083] As an example, the temperature of the feeding section of the twin-screw extruder can be 180℃, 181℃, 182℃, 183℃, 184℃, 185℃, 186℃, 187℃, 188℃, 189℃, or 190℃, or any value within the range formed by any two of the above points; the temperature of the melting section of the twin-screw extruder can be 200℃, 201℃, 202℃, 203℃, 204℃, 205℃, 206℃, 207℃, 208℃, 209℃, or 210℃, or any value within the range formed by any two of the above points; the temperature of the homogenization section of the twin-screw extruder can be 210℃, 211℃, 212℃, 213℃, 214℃, 215℃, 216℃, 217℃, 218℃, 219℃, or 220℃, or any value within the range formed by any two of the above points.

[0084] In some embodiments, the detection method further includes the step of detecting the uniformity of titanium dioxide distribution in the sample to be tested.

[0085] In some specific embodiments, the uniformity of titanium dioxide distribution in the sample is analyzed by energy dispersive spectroscopy (EDS). Optionally, the mass fraction of titanium in the polypropylene phase of the sample deviates by no more than ±0.2%.

[0086] Scanning electron microscopy can provide phase distribution information at nanometer resolution (such as the uniformity of elastomer dispersion), while polarizing microscopy reveals the orientation and size of crystal regions (micrometer level). The combination of the two can provide multi-dimensional data support for materials design.

[0087] The detection method of this application eliminates the need for post-processing dyeing, directly enhancing contrast through a blending process, thus shortening the detection cycle by more than 50%. During the material preparation stage, in-situ dispersion directly enhances the microstructural contrast, improving upon the problems of poor dyeing stability and low interface resolution in traditional techniques, providing a reliable analytical means for optimizing composite material performance. Furthermore, the method of this application is suitable for online detection in industrial production lines, such as real-time monitoring of composite material quality through rapid slicing and SEM analysis.

[0088] By analyzing the distribution patterns of crystalline and amorphous regions, processing techniques (such as cooling rate and blending temperature) can be optimized to control crystallization behavior and develop high-strength and high-toughness composite materials. Precisely locating the distribution and defects at phase interfaces (such as pores and weak bonding regions) provides a direct basis for interface modification (such as compatibilizer addition and surface treatment), thereby improving the mechanical properties and durability of materials.

[0089] The present application will be further described below with reference to specific embodiments and comparative examples, but these should not be construed as limiting the scope of protection of the present application. Unless otherwise specified, the raw materials involved in the following specific embodiments are all commercially available, the instruments used are all commercially available, and the processes involved are conventionally selected by those skilled in the art unless otherwise specified.

[0090] Example 1

[0091] (1) Surface treatment of titanium dioxide nanoparticles with a particle size of 50 nm and a mass fraction of 0.05 wt% was performed using silane coupling agent KH-550 with a mass fraction of 2%. The modified titanium dioxide nanoparticles were then blended with polypropylene resin through a twin-screw extruder to prepare titanium dioxide / polypropylene masterbatch.

[0092] The temperature of the twin-screw extruder's feeding section is 180℃, the melting section is 210℃, and the homogenization section is 220℃.

[0093] (2) The titanium dioxide / polypropylene masterbatch obtained in step (1) is melt-blended with polyolefin elastomer (POE) resin to prepare a composite material; wherein the mass ratio of polypropylene resin to elastomer resin is 60:40.

[0094] (3) Hot-press vulcanization was performed on the composite material obtained in step (2) to prepare test samples with thicknesses of 1 mm and 0.1 mm respectively.

[0095] (4) The test sample with a thickness of 1 mm was etched after being subjected to liquid nitrogen embrittlement. The distribution of polypropylene phase (whitened area) and elastomer phase (transparent area) on the brittle fracture surface of the composite material was observed using scanning electron microscopy. The crystalline region (low dispersion) and amorphous region (high dispersion) were distinguished by the enrichment state of titanium dioxide in polypropylene. The results are as follows: Figure 1 As shown.

[0096] The scanning electron microscope was used in backscattered electron mode with an accelerating voltage of 5 kV.

[0097] (5) The distribution of polypropylene crystalline regions (birefringent bright regions) and amorphous regions (dark regions) in a 0.1 mm thick sample was analyzed by polarizing microscope to further verify the phase interface bonding state; the results are as follows. Figures 2-3 As shown, Figure 2 For stained polarized light images, Figure 3 These are images taken under unpolarized light. The polarizing microscope used has a magnification of 500x.

[0098] (6) The uniformity of titanium dioxide distribution in the polypropylene phase was verified by energy dispersive spectroscopy (EDS). The deviation of the mass fraction of titanium element did not exceed ±0.2%, indicating that titanium dioxide was uniformly distributed in the polypropylene phase.

[0099] Comparative Example 1

[0100] It is basically the same as Example 1, except that: no titanium dioxide nanoparticles were added and mixed with polypropylene resin.

[0101] SEM images of the composite material prepared in Comparative Example 1 are shown below. Figure 4 As shown; the distribution diagram of crystalline and amorphous regions under a polarizing microscope is as follows. Figures 5-6 As shown, Figure 5 For stained polarized light images, Figure 6 This is an image of unpolarized light.

[0102] As can be seen from Example 1 and Comparative Example 1, the detection method of this application can clearly distinguish the crystalline region, amorphous region and phase interface of polypropylene / elastomer, which is beneficial to optimize the parameters of polypropylene / elastomer in subsequent processing technology, so as to control its crystallization behavior and thus develop high-strength and high-toughness composite materials.

[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for detecting the microstructure of a polypropylene / elastomer composite material, characterized in that, Includes the following steps: Titanium dioxide nanoparticles were dispersed and mixed with polypropylene to prepare titanium dioxide / polypropylene masterbatch; The titanium dioxide / polypropylene masterbatch is melt-blended to prepare a mixture; The mixture is then combined with an elastomer to prepare a composite material. The composite material was subjected to hot-press vulcanization to prepare a test sample, and the microstructure of the test sample was observed.

2. The method for detecting the microstructure of polypropylene / elastomer composite materials according to claim 1, characterized in that, The mass ratio of the polypropylene to the elastomer is (5~7):(3~5).

3. The method for detecting the microstructure of polypropylene / elastomer composite materials according to any one of claims 1 to 2, characterized in that, Before dispersing and mixing the titanium dioxide nanoparticles with polypropylene, the following step is also included: modifying the titanium dioxide nanoparticles with a silane coupling agent. Optionally, the mass fraction of the silane coupling agent is 1% to 3% based on the total mass of the titanium dioxide nanoparticles.

4. The method for detecting the microstructure of polypropylene / elastomer composite materials according to any one of claims 1 to 2, characterized in that, The detection method satisfies at least one of the following characteristics: (1) The particle size of the titanium dioxide nanoparticles is 10 nm to 15 nm; (2) The mass fraction of the titanium dioxide nanoparticles is 0.05% to 1% based on the total mass of the titanium dioxide nanoparticles and the polypropylene.

5. The method for detecting the microstructure of polypropylene / elastomer composite materials according to any one of claims 1 to 2, characterized in that, The thickness of the sample to be tested is 0.1 mm to 1 mm.

6. The method for detecting the microstructure of polypropylene / elastomer composite materials according to any one of claims 1 to 2, characterized in that, The microstructure of the sample under test was observed using a scanning electron microscope and / or a polarizing microscope.

7. The method for detecting the microstructure of polypropylene / elastomer composite materials according to claim 6, characterized in that, The detection method satisfies at least one of the following characteristics: (1) When observing the microstructure of the sample to be tested, the method includes scanning electron microscopy, wherein the scanning electron microscopy mode is backscattered electron mode and the accelerating voltage is 5kV~15kV; (2) When the method for observing the microstructure of the sample to be tested includes a polarizing microscope, the magnification of the polarizing microscope is 200 to 1000 times.

8. The method for detecting the microstructure of polypropylene / elastomer composite materials according to any one of claims 1 to 2, characterized in that, The titanium dioxide nanoparticles and the polypropylene are dispersed and mixed by twin-screw extrusion. Optionally, the processing temperature of the twin-screw extrusion is 180℃~220℃.

9. The method for detecting the microstructure of polypropylene / elastomer composite materials according to claim 8, characterized in that, The temperature of the feeding section of the twin-screw extruder is 180℃~190℃, the temperature of the melting section of the twin-screw extruder is 200℃~210℃, and the temperature of the homogenization section of the twin-screw extruder is 210℃~220℃.

10. The method for detecting the microstructure of polypropylene / elastomer composite materials according to any one of claims 1 to 2, characterized in that, The detection method further includes the following step: detecting the uniformity of titanium dioxide distribution in the sample to be tested.

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