Profile sample preparation method of beta-cyclodextrin microsphere modified resin embedded powder material

Abstract

The invention discloses a preparation method of a profile sample of a beta-cyclodextrin microsphere modified resin embedded powder material, and belongs to the technical field of microstructure morphology characterization. The preparation method of the profile sample comprises the following steps: mixing beta-cyclodextrin microspheres with resin, adding a to-be-detected powder material and a curing agent, mixing, spreading on a glass slide, covering with a cover glass, and curing to obtain an embedded sample; the mass of the beta-cyclodextrin microspheres is 2-10 wt% of the mass of the resin; and carrying out section cutting on the embedded sample, and polishing to obtain a section sample. The beta-cyclodextrin microspheres are introduced into the preparation of the profile sample, so that the mechanical damage to the powder in the sample preparation process can be reduced, the generation of microcracks in an embedding body is inhibited, and the imaging quality during electron microscope shooting can be improved to a certain extent.

Description

Technical Field

[0001] The present invention relates to the technical field of microstructure morphology characterization, and in particular to a method for preparing a cross-section sample of a beta-cyclodextrin microsphere modified resin-embedded powder material. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] With the rapid development of new energy vehicles and energy storage technologies, the performance optimization of lithium-ion battery powder materials has become increasingly critical to the battery's electrochemical characteristics (such as capacity, cycle life, and charge and discharge rate). To further understand the relationship between a material's microstructure and performance, cross-sectional micromorphology characterization techniques are increasingly needed. By observing characteristics such as the pore distribution, particle size, and interfacial bonding of powder materials, these characteristics can directly guide material design and process improvements.

[0004] Currently, the industry primarily uses epoxy resin-embedded powder materials to prepare cross-sectional inspection samples: the powder is mixed with epoxy resin and a curing agent, then cured to form a shape. Cutting and polishing are then performed to expose the cross-section (profile) of the material. However, this method has significant limitations: The epoxy resin is hard and brittle after curing, which can easily cause mechanical damage to the powder particles during mixing, curing, and subsequent sample preparation, leading to particle breakage or structural deformation. Furthermore, the epoxy resin generates shrinkage stress during curing, often causing microcracks within the embedding due to stress concentration. These cracks may penetrate the powder particles or be distributed at their interfaces, severely interfering with the true observation of the cross-sectional microstructure. Furthermore, the epoxy resin itself has poor electrical conductivity, which can easily induce charging effects during scanning electron microscopy (SEM) imaging, resulting in blurred or distorted images and further reducing the accuracy and reliability of micromorphological characterization. These issues limit the effectiveness of cross-sectional inspection technology for analyzing the properties of powder materials and pose challenges to the development of new materials and process optimization. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing cross-sectional samples of β-cyclodextrin microsphere-modified resin-embedded powder materials. The present invention introduces β-cyclodextrin microspheres into the preparation of cross-sectional samples, which can not only reduce the mechanical damage to the powder during the sample preparation process and inhibit the formation of microcracks inside the embedded body, but also improve the imaging quality during electron microscopy to a certain extent.

[0006] The present invention provides a method for preparing a cross-section sample of a β-cyclodextrin microsphere-modified resin-embedded powder material, comprising the following steps: After mixing β-cyclodextrin microspheres with resin, add the powder material to be tested and the curing agent, spread them flat on a glass slide after mixing, and then cover them with a cover glass. After curing, the embedded sample is obtained; the mass of the β-cyclodextrin microspheres is 2-10wt% of the mass of the resin; The embedded sample is cut into sections and polished to obtain cross-section samples.

[0007] Preferably, the resin is epoxy resin, phenolic resin or polyurethane; the curing agent is a curing agent corresponding to the resin, including epoxy resin curing agent, phenolic resin curing agent or polyurethane curing agent.

[0008] Preferably, the mass ratio of the resin, the powder material to be tested and the curing agent is 20: (0.5~4): (2~8).

[0009] Preferably, the curing temperature is 30-70° C., and the curing time is 0.5-5 h.

[0010] Preferably, the particle size of the β-cyclodextrin microspheres is 0.5-2 μm.

[0011] Preferably, the cross-section cutting is performed using an argon ion cutting instrument at 3-6 kV for 3-6 hours.

[0012] Preferably, the preparation method of the β-cyclodextrin microspheres comprises the following steps: Beta-cyclodextrin is dissolved in a sodium hydroxide aqueous solution, epichlorohydrin is added, and then an oil phase containing an emulsifier is added, and the mixture is heated for reaction. The product is then filtered, washed, and dried to obtain beta-cyclodextrin microspheres.

[0013] Furthermore, the molar ratio of the β-cyclodextrin to epichlorohydrin is 1:(8~15); the concentration of the sodium hydroxide aqueous solution is 30~40wt%, and the usage ratio of the β-cyclodextrin to the sodium hydroxide aqueous solution is 1g:(5~20)mL.

[0014] Furthermore, the emulsifier is a composite emulsifier of Span80 and Tween20, and the mass ratio of Span80 to Tween20 is (3~5):1; the oil phase is liquid paraffin, kerosene, vegetable oil or silicone oil; the amount of the emulsifier is 2~8wt% of the mass of the oil phase; and the volume fraction of the oil phase is 60~80%.

[0015] Furthermore, the temperature of the heating reaction is 50-80° C., and the heating reaction time is 4-8 hours.

[0016] Compared with the prior art, the present invention has achieved the following beneficial effects: The present invention embeds β-cyclodextrin microspheres mixed with a resin, a powder material to be tested, and a curing agent, and utilizes the abundant active groups such as hydroxyl groups on the surface of the β-cyclodextrin microspheres to form chemical bonds with the resin, thereby absorbing and dispersing the internal stress generated by the curing shrinkage of the epoxy resin, and inhibiting the generation and expansion of microcracks inside the embedding body; at the same time, the β-cyclodextrin microspheres and the resin form a "soft-hard" composite structure, which effectively buffers the mechanical impact of the hard and brittle properties of the epoxy resin on the powder particles, and significantly reduces the powder breakage rate and structural deformation risk during mixing, curing, and cutting; in addition, the introduction of β-cyclodextrin microspheres can reduce the dielectric constant and dielectric loss of the resin, effectively alleviate the charging effect of the epoxy resin itself, and improve the clarity of electron microscope images and the accuracy of characterization, thereby providing a reliable cross-section sample basis for the performance analysis of lithium-ion battery powder materials and the research and development of electrode powder materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute undue limitations thereon. It is obvious that one of ordinary skill in the art could derive other drawings based on these drawings without inventive effort.

[0018] Figure 1 is a scanning electron microscope image of β-cyclodextrin microspheres according to an embodiment of the present invention; Figure 2 is a scanning electron microscope image of a cross-section sample of Example 1 of the present invention; Figure 3 is a scanning electron microscope image of a cross-section sample of Comparative Example 1 of the present invention; Figure 4 3 is a comparison chart of the resistance values ​​of the cross-section samples of Examples 1 to 3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0020] The present invention provides a method for preparing a cross-section sample of a β-cyclodextrin microsphere-modified resin-embedded powder material, comprising the following steps: After mixing β-cyclodextrin microspheres with resin, add the powder material to be tested and the curing agent, spread them flat on a glass slide after mixing, and then cover them with a cover glass. After curing, the embedded sample is obtained; the mass of the β-cyclodextrin microspheres is 2-10wt% of the mass of the resin; The embedded sample is cut into sections and polished to obtain cross-section samples.

[0021] β-cyclodextrin microspheres (hereinafter referred to as "microspheres") serve as the modified component. Their surface is rich in reactive groups such as hydroxyl groups (-OH), which serve as key functional sites. During the mixing stage, when the microspheres come into contact with the resin, the hydroxyl groups chemically bond with functional groups in the resin, forming a covalent connection at the "microsphere-resin" interface. This chemical bonding not only strengthens the bond between the microspheres and the resin matrix, but more importantly, as the dispersed phase, the microspheres absorb and disperse the internal stress generated by the resin's curing shrinkage through their own elastic deformation during cross-linking and curing. During resin curing, the molecular chains cross-link and shrink. If stress cannot be effectively released, microcracks can easily form within the embedded body. The elastic buffering effect of the microspheres reduces stress concentration, inhibits crack formation and propagation, and thus prevents cracks from penetrating the test powder material or its interface. This also reduces breakage or structural deformation of the test powder material. Furthermore, the hollow structure of β-cyclodextrin microspheres can accommodate polar small molecules, reducing the number of polarizable groups in the resin and thus lowering the dielectric constant. The hydroxyl groups (-OH) of the β-cyclodextrin microspheres react with the resin curing agent, consuming polar groups in the cross-linked network and slowing the polarization deflection of the dipoles under an external electric field, further reducing dielectric loss. A decrease in the dielectric constant weakens the resin's insulation and reduces its resistivity (i.e., resistance), facilitating electron beam penetration and thus improving the signal-to-noise ratio of electron microscope imaging. The introduction of β-cyclodextrin microspheres can also serve as reference particles. If the β-cyclodextrin microspheres rupture after imaging, the sample preparation process can be further adjusted to avoid adverse effects on the powder material being tested. Therefore, they can provide guidance for the sample preparation process to a certain extent.

[0022] In the above-mentioned technical solution, the first step, mixing the microspheres with the resin, utilizes the resin's low viscosity (liquid before curing) to promote uniform dispersion of the microspheres within the resin, forming a "microsphere-resin" pre-dispersion. The second step, adding the powder material to be tested and a curing agent, prevents aggregation of the powder particles. Laying the microspheres flat on a glass slide and covering them with a coverslip not only physically controls the thickness of the embedded body, preventing excessive thickness from leading to incomplete curing or stress concentration, but also ensures the smoothness of the top surface of the embedded body. After final sample preparation, cross-sections of the samples are used for electron microscopy. The present invention imposes no particular restrictions on the specific testing process; commonly used electron microscopy methods in the art can be employed.

[0023] In the present invention, the mass of the β-cyclodextrin microspheres is 2 to 10 wt % of the resin mass. If the content of the β-cyclodextrin microspheres is too low, the volume of the dispersed phase of the microspheres is insufficient, an effective stress dispersion network cannot be formed, the effect of inhibiting shrinkage and crack propagation is not obvious, and the improvement of dielectric properties is not significant. If the content of the β-cyclodextrin microspheres is too high, it will lead to microsphere agglomeration. The defect effect caused by this phenomenon exceeds its modification effect, the dielectric properties deteriorate, and further lead to a decrease in imaging clarity. The mass of the β-cyclodextrin microspheres is more preferably 2 to 6 wt %.

[0024] The present invention does not impose any particular limitation on the specific type of powder material to be tested. For example, powder materials such as positive electrode active materials, negative electrode active materials, conductive agents, and binders in lithium-ion batteries can be characterized.

[0025] In this invention, the resin is an epoxy resin, phenolic resin, or polyurethane; its molecular structure is linear or branched (liquid or low-viscosity) before curing, and forms a three-dimensional network structure (solid) through cross-linking after curing. Polar groups on the resin molecular chain (such as epoxy, hydroxymethyl, and carbamate groups) can form hydrogen bonds or chemical bonds with hydroxyl groups on the surface of β-cyclodextrin microspheres and oxygen-containing groups on the surface of the test powder material, enhancing the interfacial bonding strength of the embedded structure. Compared with thermoplastic resins, it has a lower cure shrinkage rate, which can reduce internal stress concentration caused by volume change and reduce the risk of microcracking. It also has better temperature resistance and aging resistance, preventing degradation of the embedded sample during subsequent cutting and characterization.

[0026] The curing agent in the present invention is a curing agent corresponding to the resin, including epoxy resin curing agent, phenolic resin curing agent or polyurethane curing agent. The present invention does not impose any special restrictions on the specific curing agent components and models, and any curing agent commonly used in the art can be used.

[0027] In the present invention, the mass ratio of the resin, test powder material, and curing agent is 20:(0.5-4):(2-8). The resin, as the continuous phase, must provide sufficient volume to encapsulate the test powder material and provide mechanical support. The test powder material, as the dispersed phase, must balance characterization requirements and dispersion uniformity.

[0028] In the present invention, the curing temperature is 30-70° C. and the curing time is 0.5-5 hours. The curing agent is used to crosslink and solidify the resin, thereby stabilizing the internal β-cyclodextrin microspheres and the powder material to be tested.

[0029] In the present invention, the β-cyclodextrin microspheres have a particle size of 0.5 to 2 μm. Too small a particle size results in an excessively large specific surface area, which can easily lead to agglomeration and uneven dispersion in the resin, preventing effective stress dispersion and dielectric modification. If the particle size of the β-cyclodextrin microspheres is too large, they may compete with the powder for dispersion, resulting in a reduced uniformity of the two particle types within the embedded structure.

[0030] In the present invention, the cross section cutting is performed using an argon ion cutting instrument at 3-6 kV for 3-6 hours. + ) bombards the surface of the embedded body and peels off the material layer by layer through the "sputtering effect", avoiding the powder crushing or embedding cracking caused by shear force of traditional mechanical cutting (such as diamond knife).

[0031] In the present invention, the preparation method of the β-cyclodextrin microspheres comprises the following steps: Beta-cyclodextrin is dissolved in a sodium hydroxide aqueous solution, epichlorohydrin is added, and then an oil phase containing an emulsifier is added, and the mixture is heated for reaction. The product is then filtered, washed, and dried to obtain beta-cyclodextrin microspheres.

[0032] The above preparation method synthesizes β-cyclodextrin microspheres by the reverse emulsion method. The β-cyclodextrin (β-CD) molecule contains multiple hydroxyl groups (-OH), which can be "deprotonated" in alkaline solution (NaOH provides OH⁻), thereby enhancing its hydrophilicity. - As a catalyst, it can promote the subsequent cross-linking reaction with epichlorohydrin.

[0033] In the present invention, the molar ratio of β-cyclodextrin to epichlorohydrin is 1:(8-15); the concentration of the sodium hydroxide aqueous solution is 30-40wt%, and the dosage ratio of β-cyclodextrin to sodium hydroxide aqueous solution is 1g:(5-20)mL. Epichlorohydrin (ECH) is a crosslinking agent. The epoxy group (-COC-) in its molecule can react with the -O - Na + Nucleophilic substitution reaction occurs (-O - Attacking the C atom of the epoxy group, opening the ring to form an ether bond [-COC-]), multiple β-CD molecules are connected into a network structure to construct a microsphere skeleton. The molar ratio of β-CD to β-cyclodextrin ensures that the formed microspheres have a suitable cross-linking density.

[0034] In the present invention, the emulsifier is a composite emulsifier of Span80 and Tween20, and the mass ratio of Span80 to Tween20 is (3-5):1; the oil phase is liquid paraffin, kerosene, vegetable oil or silicone oil; the amount of the emulsifier is 2-8wt% of the mass of the oil phase; the volume fraction of the oil phase is 60-80%, and the oil phase serves as the continuous phase, and its volume fraction determines the dispersion degree of the aqueous phase droplets.

[0035] In the present invention, the heating reaction temperature is 50-80°C and the heating reaction time is 4-8 hours. The heating reaction is the core stage of the cross-linking reaction. Below 50°C, the molecular thermal motion is insufficient, and the cross-linking rate is slow. Above 80°C, ECH is easily volatile (boiling point 117°C), resulting in loss of the cross-linking agent and insufficient cross-linking of the microspheres.

[0036] The present invention does not impose any particular restrictions on the specific washing and drying processes, and the washing and drying processes commonly used in the art can be used. After drying, a screening step is also included to obtain β-cyclodextrin microspheres with more uniform particle size.

[0037] The technical solution of the present invention is further described below with reference to specific examples. The present invention has no particular limitation on the sources of the reagents used in the following examples, and commercially available products known to those skilled in the art can be used.

[0038] In the following examples, the preparation method of β-cyclodextrin microspheres is as follows: (1) Weigh 10.0 g of β-cyclodextrin (β-CD, purity ≥98%) and add it to a 250 mL three-necked flask pre-filled with 100 mL of 35 wt% sodium hydroxide aqueous solution (the ratio of β-CD to NaOH solution is 1 g:10 mL). Stir magnetically at 300 rpm in a 30 °C water bath for 20 minutes until β-CD is completely dissolved to form a clear alkaline solution. Then, add about 6.92 mL of epichlorohydrin (the molar ratio of β-CD to epichlorohydrin is 1:10) dropwise to the solution using a constant pressure dropping funnel. Control the dropping speed to about 1 drop / second. The addition is completed within 20 minutes. Continue stirring the reaction for 1.5 hours to perform pre-crosslinking.

[0039] (2) After the pre-crosslinking is completed, 250 mL of liquid paraffin (70% oil phase volume fraction) in which 10.75 g of composite emulsifier (Span80 and Tween20 mass ratio of 4:1, accounting for 5 wt% of the oil phase mass) has been pre-dissolved is added to the system, and a stable oil-in-water (O / W) emulsion is formed by high-speed stirring (1500 rpm) for 10 minutes; then the water bath temperature is raised to 70 °C, the stirring speed is reduced to 500 rpm, and the reaction is continued for 6 hours to complete the crosslinking.

[0040] (3) After the reaction, the product was collected by filtration through a 0.22 μm microporous filter membrane, and the residual alkali solution was neutralized with 0.1 mol / L hydrochloric acid solution (100 mL × 3 times), the unreacted epichlorohydrin and the oil phase were dissolved with anhydrous ethanol (100 mL × 2 times), the water-soluble impurities were removed with deionized water (100 mL × 3 times), and the water was dehydrated with acetone (50 mL × 2 times) until the washing solution was neutral; finally, the filter cake was placed in a vacuum drying oven at 60 ° C for 24 hours and passed through a 200 mesh sieve to obtain white powdery β-cyclodextrin microspheres, the scanning electron microscope image of which is shown in FIG. Figure 1 As shown, it can be seen that the particle size is about 1 μm.

[0041] Example 1 This embodiment provides a method for preparing cross-section samples of a β-cyclodextrin microsphere-modified resin-embedded powder material.

[0042] Weigh 20g of epoxy resin (E-51 type) and add it into a 50mL plastic beaker. Add β-cyclodextrin microspheres according to 5wt% (i.e. 1g) of the resin mass. Place it in a planetary mixer and stir at 1000rpm for 2 minutes to evenly disperse the microspheres in the resin to form a first mixture. Then, add 2g of the lithium-ion battery ternary positive electrode material Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 (NCM523, particle size of 5-10 μm), continue stirring at 1000 rpm for 1 minute until the powder is initially dispersed, then add 5 g of ethylenediamine curing agent (resin: curing agent mass ratio is 20:5), and stir at 1000 rpm for 2 minutes to form a uniform second mixture.

[0043] Pour the second mixture onto the center of a glass slide (75 mm × 25 mm × 1 mm), cover it lightly with a coverslip, and spread the mixture into a uniform film about 0.5 mm thick (avoid bubbles). Then place it in a constant temperature drying oven at 50°C to cure for 3 hours. After the resin is completely cross-linked, take it out to obtain an embedded sample.

[0044] The embedded sample was fixed on the sample stage of the argon ion cutting instrument, and the acceleration voltage was set to 5 kV and the cutting time was 5 hours. The material was peeled off layer by layer through argon ion beam bombardment until the core cross-section of the powder particles was exposed. After cutting, it was mechanically polished for 10 minutes with nano-silica polishing liquid to remove the surface residual stress layer to obtain a smooth cross-section sample.

[0045] The cross-section sample was attached to the scanning electron microscope (SEM) sample stage and sprayed with gold (thickness of about 5 nm), and then observed in a Thermo Fisher APero 2C field emission scanning electron microscope. Figure 2 As shown, the dark grey spherical particles are β-cyclodextrin microspheres with a particle size of about 1 μm, and the particle size of the NCM powder material is about 7 μm. The overall image is clear and bright.

[0046] Example 2 This embodiment provides a method for preparing cross-section samples of a β-cyclodextrin microsphere-modified resin-embedded powder material.

[0047] Weigh 20g of epoxy resin (E-51 type) and add it into a 50mL plastic beaker. Add β-cyclodextrin microspheres according to 2.5wt% (i.e. 0.5g) of the resin mass. Place it in a planetary mixer and stir at 1000rpm for 2 minutes to evenly disperse the microspheres in the resin to form a first mixture. Then add 2g of the lithium-ion battery positive electrode ternary material Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 (NCM523, particle size of 5-10 μm), continue stirring at 1000 rpm for 1 minute until the powder is initially dispersed, then add 5 g of ethylenediamine curing agent (resin: curing agent mass ratio is 20:5), and stir at 1000 rpm for 2 minutes to form a uniform second mixture.

[0048] Pour the second mixture onto the center of a glass slide (75 mm × 25 mm × 1 mm), cover it lightly with a coverslip, and spread the mixture into a uniform film about 0.5 mm thick (avoid bubbles). Then place it in a constant temperature drying oven at 50°C to cure for 3 hours. After the resin is completely cross-linked, take it out to obtain an embedded sample.

[0049] The embedded sample was fixed on the sample stage of the argon ion cutting instrument, and the acceleration voltage was set to 5 kV and the cutting time was 5 hours. The material was peeled off layer by layer through argon ion beam bombardment until the core cross-section of the powder particles was exposed. After cutting, it was mechanically polished for 10 minutes with nano-silica polishing liquid to remove the surface residual stress layer to obtain a smooth cross-section sample.

[0050] Example 3 This embodiment provides a method for preparing cross-section samples of a β-cyclodextrin microsphere-modified resin-embedded powder material.

[0051] Weigh 20g of epoxy resin (E-51 type) and add it into a 50mL plastic beaker. Add β-cyclodextrin microspheres according to 10wt% of the resin mass (i.e. 2g). Place it in a planetary mixer and stir at 1000rpm for 2 minutes to evenly disperse the microspheres in the resin to form a first mixture. Then add 2g of the lithium-ion battery positive electrode ternary material Li(Ni 0.5 Co 0.2 Mn 0.3)O2 (NCM523, particle size of 5-10 μm), continue stirring at 1000 rpm for 1 minute until the powder is initially dispersed, then add 5 g of ethylenediamine curing agent (resin: curing agent mass ratio is 20:5), and stir at 1000 rpm for 2 minutes to form a uniform second mixture.

[0052] Pour the second mixture onto the center of a glass slide (75 mm × 25 mm × 1 mm), cover it lightly with a coverslip, and spread the mixture into a uniform film about 0.5 mm thick (avoid bubbles). Then place it in a constant temperature drying oven at 50°C to cure for 3 hours. After the resin is completely cross-linked, take it out to obtain an embedded sample.

[0053] The embedded sample was fixed on the sample stage of the argon ion cutting instrument, and the acceleration voltage was set to 5 kV and the cutting time was 5 hours. The material was peeled off layer by layer through argon ion beam bombardment until the core cross-section of the powder particles was exposed. After cutting, it was mechanically polished for 10 minutes with nano-silica polishing liquid to remove the surface residual stress layer to obtain a smooth cross-section sample.

[0054] Comparative Example 1 Compared with Example 1, this comparative example does not add β-cyclodextrin microspheres.

[0055] The SEM image of the cross-section sample of this comparative example is as follows Figure 3 As shown, it can be seen that the diameter of the NCM particles is about 5~10nm, and microcracks appear.

[0056] Test example 1. Resistance measurement of cross-section samples The resistance values ​​of the cross-section samples of Examples 1 to 3 were measured by a plate resistance meter. Figure 4 As shown in the figure, it can be seen that the cross-section sample of Example 1 exhibits the lowest resistance value, while the resistance value of Comparative Example 1 is the highest, nearly twice that of Example 1. This shows that the addition of an appropriate amount of β-cyclodextrin microspheres is conducive to obtaining a cross-section sample with lower resistance, which is beneficial to improving the clarity of imaging.

[0057] Determination of the Breakage Rate The cross-section samples of the Examples and Comparative Examples were observed by SEM (Thermo Fisher APero 2C). 100 NCM523 particles were randomly counted and the proportion of broken particles (particle edge fracture or internal cracks) was calculated. The statistical results are summarized in Table 1.

[0058] Table 1 Test results of broken particle ratio

[0059] From the experimental results, it can be seen that the addition of β-cyclodextrin microspheres significantly reduced the proportion of broken particles, indicating that it can play a certain role in buffering stress.

[0060] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing cross-section samples of β-cyclodextrin microsphere-modified resin-embedded powder materials, characterized in that: The steps include: After mixing β-cyclodextrin microspheres with resin, add the powder material to be tested and the curing agent, spread them flat on a glass slide after mixing, and then cover them with a cover glass. After curing, the embedded sample is obtained; the mass of the β-cyclodextrin microspheres is 2-10wt% of the mass of the resin; The embedded sample is cut into sections and polished to obtain cross-section samples.

2. The cross-section sample preparation method according to claim 1, wherein: The resin is epoxy resin, phenolic resin or polyurethane; the curing agent is a curing agent corresponding to the resin, including epoxy resin curing agent, phenolic resin curing agent or polyurethane curing agent.

3. The cross-section sample preparation method according to claim 1, wherein: The mass ratio of the resin, the powder material to be tested and the curing agent is 20: (0.5~4): (2~8).

4. The cross-section sample preparation method according to claim 1, wherein: The curing temperature is 30-70° C., and the curing time is 0.5-5 hours.

5. The cross-section sample preparation method according to claim 1, wherein: The particle size of the β-cyclodextrin microspheres is 0.5-2 μm.

6. The cross-section sample preparation method according to claim 1, wherein: The cross-section cutting is performed using an argon ion cutting instrument at 3-6 kV for 3-6 hours.

7. The cross-section sample preparation method according to claim 1, wherein: The preparation method of the β-cyclodextrin microspheres comprises the following steps: Beta-cyclodextrin is dissolved in a sodium hydroxide aqueous solution, epichlorohydrin is added, and then an oil phase containing an emulsifier is added, and the mixture is heated for reaction. The product is then filtered, washed, and dried to obtain beta-cyclodextrin microspheres.

8. The cross-section sample preparation method according to claim 7, wherein: The molar ratio of the β-cyclodextrin to epichlorohydrin is 1:(8-15); the concentration of the sodium hydroxide aqueous solution is 30-40wt%, and the usage ratio of the β-cyclodextrin to the sodium hydroxide aqueous solution is 1g:(5-20)mL.

9. The cross-section sample preparation method according to claim 7, wherein: The emulsifier is a composite emulsifier of Span80 and Tween20, and the mass ratio of Span80 to Tween20 is (3-5):1; the oil phase is liquid paraffin, kerosene, vegetable oil or silicone oil; the amount of the emulsifier is 2-8wt% of the mass of the oil phase; and the volume fraction of the oil phase is 60-80%.

10. The cross-section sample preparation method according to claim 7, wherein: The temperature of the heating reaction is 50-80° C., and the heating reaction time is 4-8 hours.

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