A polystyrene-based nanocomposite insulating material with low body charge accumulation

Abstract

The present invention provides a polystyrene-based nanocomposite insulating material with a low body charge accumulation amount. Specifically, a nano-core cadmium selenide nanopowder is prepared, and zinc sulfide is coated on the cadmium selenide nanopowder to obtain a core-shell nano-zinc sulfide-coated cadmium selenide nanopowder, and the diameter and shape of the core-shell nano-zinc sulfide-coated cadmium selenide nanopowder are measured; the core-shell nano-zinc sulfide-coated cadmium selenide nanopowder and polystyrene are respectively dissolved in dichloromethane and mixed to obtain the polystyrene-based nanocomposite insulating material. The added zinc sulfide-coated cadmium selenide nanopowder in the present invention is a core-shell sphere and exists in the form of smaller clusters in polystyrene, forming a good interaction with polystyrene, improving the performance of polystyrene under the action of an electric field, and effectively reducing the space charge accumulation amount in polystyrene under a high electric field. The nanopowder in the polystyrene-based nanocomposite insulation prepared by this method has good dispersibility, and the required content of the zinc sulfide-coated cadmium selenide nanopowder is low, with low cost.

Description

Technical Field

[0001] The invention relates to a polystyrene-based nanocomposite insulation with low volume charge accumulation, which is particularly suitable for polystyrene-based insulation materials used under high DC electric field strength. Background Art

[0002] As a thermoplastic resin, polystyrene has been used as an insulating material in pulse power devices, field effect transistors, etc. due to its excellent electrical properties, mechanical properties and processability. However, as the voltage level increases, charges will inevitably be injected from the electrodes into the polystyrene, forming space charge accumulation in the body. On the one hand, the accumulation of space charge will change the electric field distribution in the polystyrene, making the local electric field distribution uneven. The polystyrene subjected to a higher electric field strength will age rapidly, affecting its service life. On the other hand, if more space charge accumulates in the polystyrene, when the external electric field is reversed, the polystyrene will break down at a lower electric field strength. This will not only affect the life of polystyrene as an insulator, but also the overall safety of the device.

[0003] At present, there are few reports on the problem of charge accumulation in polystyrene under the action of DC electric field. Existing literature on improving polystyrene insulation, such as "Preparation and surface flashover performance of mica / cross-linked polystyrene composite materials" published by Ke Changfeng et al. of Northwest Institute of Nuclear Technology, introduced the method of preparing mica / cross-linked polystyrene composite materials by in-situ free radical polymerization, and studied the effect of mica on the vacuum surface flashover performance of cross-linked polystyrene. It was concluded that when a certain mass of mica was added, the vacuum surface flashover breakdown voltage and electrical life of polystyrene would be improved, but it did not explain whether this method could inhibit the accumulation of charge in polystyrene. Some other research papers focus on improving the impact resistance or toughness of polystyrene. For example, the article "Preparation and Mechanical Properties of Thermoplastic Elastomer Modified Polystyrene Composites" published by Lu Xiaoran et al. from East China Normal University introduced a blended composite material based on polystyrene modified by thermoplastic elastomer "styrene-butadiene-styrene block copolymer". By testing the toughness and thermal properties of the composite material, the impact strength, melt fluidity, thermal stability, etc. of the modified polystyrene composite material were determined, but it did not mention whether the charge accumulation in polystyrene under a DC electric field can be reduced.

[0004] The existing patent "A High Thermal Conductivity Polystyrene Resin-Based Composite Material and Its Preparation Method" with the publication number CN106280049A provides a high thermal conductivity polystyrene composite material by adding boron nitride and boron nitride nanosheets. The patent content details the preparation method of the polystyrene composite material. The mentioned preparation method of the polystyrene composite material is applicable to high-temperature environments and does not mention whether it can reduce the accumulation of charges in polystyrene under high DC field strength. The patent "A Nano Boron Nitride-Polyimide Modified Polystyrene Insulating Material and Its Preparation Method" with the publication number CN111675875A provides a material preparation method for improving the insulation performance and heat resistance of polystyrene. The patent content details the production process of the nano boron nitride-polyimide modified polystyrene insulating material. The insulation performance and heat resistance of the mentioned modified polystyrene insulating material are both improved, and the resistivity of the modified polystyrene insulation is increased, without mentioning whether it can reduce the accumulation amount of volume charges in polystyrene under the action of an electric field. Summary of the Invention

[0005] In order to solve the deficiencies and defects of rapid aging, low lifespan, and easy breakdown caused by the accumulation of internal charges when polystyrene is used as an insulating material; the purpose of the present invention is to provide a polystyrene-based nano-composite insulating material that can reduce the accumulation amount of volume charges in polystyrene under the action of an electric field and improve the service life and reliability of polystyrene as a device insulation.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is to provide a polystyrene-based nano-composite insulating material with a low volume charge accumulation amount. The specific preparation process is as follows: Prepare nano-core cadmium selenide nano-powder, coat zinc sulfide on the cadmium selenide nano-powder to obtain core-shell nano-zinc sulfide-coated cadmium selenide nano-powder, measure the diameter and shape of the core-shell nano-zinc sulfide-coated cadmium selenide nano-powder, and determine that the diameter is 4.75 nm and the shape is spherical; dissolve the core-shell nano-zinc sulfide-coated cadmium selenide nano-powder and polystyrene in dichloromethane respectively and mix them to obtain a polystyrene-based nano-composite insulating material containing 0.1 wt% zinc sulfide, and measure that the core-shell nano-zinc sulfide-coated cadmium selenide nano-powder exists in the form of clusters with an average diameter of 20 nm in polystyrene; measure the internal space charge density of the polystyrene-based nano-composite insulating material under a +50 k / mm DC electric field, calculate the internal charge amount at different pressurization times, and determine whether the internal space charge amount of the prepared polystyrene-based nano-composite insulating material is lower than the space charge amount in pure polystyrene, that is, whether the purpose of inhibiting the volume charge accumulation amount is achieved.

[0007] Preparation of the nanocore-cadmium selenide nanopowder: In an argon atmosphere, cadmium oxide powder, octadecenoic acid solution, and octadecene solution with a molar ratio of 1:3:140 were mixed, and selenium powder, butyltriphenylphosphine, and octadecene solution with a molar ratio of 1:1.1:140 were mixed. The mixing temperature was 320 °C. The two mixtures were mixed and cooled to 290 °C to allow the growth of cadmium selenide crystals. After the mixed solution containing cadmium selenide crystals was cooled to 40 °C, it was mixed with chloroform, centrifuged, and extracted with methanol or acetone to obtain spherical cadmium selenide nanopowder, that is, the nanocore-cadmium selenide nanopowder.

[0008] Preparation of the core-shell nano-zinc sulfide-coated cadmium selenide nanopowder: In an argon atmosphere, zinc oxide powder, octadecenoic acid solution, and octadecene solution with a molar ratio of 1.3:3:140 were mixed, and sulfur powder, butyltriphenylphosphine, and octadecene solution with a molar ratio of 1:1.8:140 were mixed. The mixing temperature was 320 °C. The two mixtures were mixed, and cadmium selenide nanopowder was added, and cooled to 250 °C to allow the growth of zinc sulfide crystals on cadmium selenide. After the mixed solution containing zinc sulfide-coated cadmium selenide crystals was cooled to 40 °C, it was mixed with chloroform, centrifuged, and extracted with methanol or acetone to obtain spherical zinc sulfide-coated cadmium selenide core-shell nanopowder, that is, the core-shell nano-zinc sulfide-coated cadmium selenide nanopowder.

[0009] The core-shell nano-zinc sulfide-coated cadmium selenide nanopowder was measured for nanopowder diameter and characterized for morphology, and the diameter of the cadmium selenide nanopowder was found to be 4.77 nm, and the diameter of the zinc sulfide-coated cadmium selenide nanopowder was 4.75 nm. Both the cadmium selenide nanopowder and the zinc sulfide-coated cadmium selenide nanopowder were spheres.

[0010] Preparation of the polystyrene-based nanocomposite insulating material: Using polystyrene as the matrix material, polystyrene was dissolved in dichloromethane at room temperature with a mass ratio of 1:6.5; the core-shell nano-zinc sulfide-coated cadmium selenide nanopowder was dissolved in dichloromethane with a mass ratio of 1:1.1; the two mixed solutions were fully mixed, extracted with isopropanol, and filtered to obtain a mixture of polystyrene and zinc sulfide-coated cadmium selenide nanopowder, that is, the polystyrene-based nanocomposite insulating material. The mass ratio of the core-shell nano-zinc sulfide-coated cadmium selenide nanopowder to polystyrene was 1:1000; the polystyrene-based nanocomposite insulating material was hot-pressed into the required shape for use.

[0011] For the preparation of the polystyrene-based nanocomposite insulating material, the mixing effect of the polystyrene and the nanopowder was characterized, and it was found that the zinc sulfide-coated cadmium selenide nanopowder in the polystyrene-based nanocomposite existed in the form of clusters with a diameter of 20 nm.

[0012] Analysis of the in - vivo charge accumulation amount of polystyrene - based nanocomposite insulation shows that the in - vivo charge amount of the polystyrene - based nanocomposite insulation with cadmium selenide nanoparticles coated with zinc sulfide is less than 0.45 μC under a DC electric field of +50 kV / mm.

[0013] The beneficial effects of the present invention are as follows: The added cadmium selenide nanoparticles coated with zinc sulfide are core - shell spheres, which exist in the form of smaller clusters in polystyrene and form good interactions with polystyrene, improving the performance of polystyrene under the action of an electric field and effectively reducing the space - charge accumulation amount in polystyrene under a high electric field. The nanometer powder in the polystyrene - based nanocomposite insulation prepared by this method has good dispersibility, requires a low content of cadmium selenide nanoparticles coated with zinc sulfide, and has low cost. Brief Description of the Drawings

[0014] Figure 1 Flow chart of the method for reducing the in - vivo charge accumulation of polystyrene - based nanocomposite insulation in a DC electric field in this invention patent;

[0015] Figure 2 Absorption spectrum diagram of the nanometer powder in this invention patent;

[0016] Figure 3 External shape diagram of the nanometer powder in this invention patent;

[0017] Figure 4 External shape diagram of the zinc - sulfide - coated nanometer powder in this invention patent;

[0018] Figure 5 Distribution diagram of nanometer powder in the polystyrene matrix in this invention patent;

[0019] Figure 6 Principle diagram of the space - charge measurement technology in this invention patent;

[0020] Figure 7 Distribution diagram of the in - vivo space - charge density of pure polystyrene in this invention patent;

[0021] Figure 8 Distribution diagram of the in - vivo space - charge density of nanocomposite insulation in the polystyrene matrix in this invention patent;

[0022] In the figure: 1. Pulse power supply; 2. Polystyrene - based nanocomposite insulation material; 3. 50 Ω resistor; 4. Coupling capacitor; 5. High - voltage electrode; 6. PVDF - TrEF film; 7. High - voltage resistor; 8. DC power supply; 9. Ground electrode; 10. Amplifier; 11. Oscilloscope. Detailed Embodiments

[0023] The following further explains the detailed embodiments of the present invention with reference to the accompanying drawings.

[0024] As shown in the atta Figure 1, the polystyrene-based nano-composite insulation provided by the present invention is a method designed to reduce the charge accumulation in the body of polystyrene insulation under the action of an electric field on the basis of the prior art. Its specific process mainly includes: preparation of nano-core cadmium selenide nano-powder, preparation of core-shell nano-zinc sulfide-coated cadmium selenide nano-powder, measurement of the diameter of the nano-powder and morphological characterization, preparation of polystyrene-based nano-composite insulation, characterization of the mixing effect of polystyrene and nano-powder, and analysis of the charge accumulation amount in the body of polystyrene-based nano-composite insulation.

[0025] Preparation of nano-core cadmium selenide nano-powder: Mix 0.1 mmol of cadmium oxide powder, 0.3 mmol of oleic acid solution and 14 mmol of octadecene solution (molar ratio 1:3:140) in an argon atmosphere and heat to 320 °C; after complete dissolution, add a mixture of trioctylphosphine oxide and hexadecylamine as a surfactant to prevent the aggregation of the formed cadmium selenide crystals. Maintain the argon atmosphere and add an octadecene solution containing 0.03 mmol of selenium powder and butyltriphenylphosphine (molar ratio of selenium to butyltriphenylphosphine 1:1.1) to the mixture. Then stir continuously and cool the reaction mixture to 290 °C to allow the growth of cadmium selenide crystals. After cooling the mixture containing cadmium selenide crystals to about 40 °C, mix it with chloroform and remove the white insoluble solids floating on the top of the solution by centrifugation. Finally, add methanol or acetone to the solution and obtain spherical cadmium selenide nano-powder by centrifugal precipitation.

[0026] Preparation of core-shell nano-zinc sulfide-coated cadmium selenide nano-powder: Mix 0.13 mmol of zinc oxide powder, 0.3 mmol of oleic acid solution and 14 mmol of octadecene solution (molar ratio 1.3:3:140) in an argon atmosphere and heat to 320 °C; after complete dissolution, add a mixture of trioctylphosphine oxide and hexadecylamine as a surfactant to prevent the aggregation of the formed zinc sulfide-coated cadmium selenide crystals. Maintain the argon atmosphere and add an octadecene solution containing 0.05 mmol of sulfur powder and butyltriphenylphosphine (sulfur to butyltriphenylphosphine 1:1.1) to the mixture. At the same time, add cadmium selenide nano-powder to the mixture. Then stir continuously and cool the reaction mixture to 250 °C to allow the growth of zinc sulfide crystals on cadmium selenide. After cooling the mixture containing zinc sulfide-coated cadmium selenide crystals to about 40 °C, mix it with chloroform and remove the white insoluble solids floating on the top of the solution by centrifugation. Finally, add methanol or acetone to the solution and obtain zinc sulfide-coated cadmium selenide core-shell nano-powder by centrifugal precipitation.

[0027] As attached Figures 2 - 4As shown, the measurement of the diameter and the morphological characterization of the nano-powders are to obtain the sizes and shapes of the core and the shell of the cadmium selenide core-shell nano-powders coated with zinc sulfide, ensuring that the polystyrene-based nano-composite insulation has a better volume charge suppression effect. At room temperature, a small amount of the prepared cadmium selenide nano-powders and cadmium selenide nano-powders coated with zinc sulfide are respectively dissolved in dichloromethane, and the wavelengths corresponding to the peak values of the exciton absorption peaks of the two kinds of powders are measured using an ultraviolet-visible spectrometer. λ (unit: nm). The peak of the cadmium selenide nano-powders should be 604 nm, and the peak of the cadmium selenide nano-powders coated with zinc sulfide should be 592 nm. The particle size is calculated according to the following formula D (unit: nm). The diameter of the cadmium selenide nano-powders is 4.77±1 nm, and the diameter of the cadmium selenide nano-powders coated with zinc sulfide is 4.75±1 nm (where the diameter of the cadmium selenide nano-powders is 4.25 nm and the thickness of the zinc sulfide shell is 0.5 nm). It is observed by transmission electron microscopy that the prepared cadmium selenide nano-powders and cadmium selenide nano-powders coated with zinc sulfide are both spherical.

[0028]

[0029] Preparation of polystyrene-based nano-composite insulation materials: Weigh 5 g of polystyrene matrix materials and dissolve them in 25 mL of dichloromethane organic solvent at room temperature, with a mass ratio of 1:6.5; at the same time, weigh 5 mg of core-shell nano-cadmium selenide nano-powders coated with zinc sulfide and dissolve them in 3 mL of dichloromethane, with a mass ratio of 1:1.1; the mass ratio of the core-shell nano-cadmium selenide nano-powders coated with zinc sulfide to polystyrene is 1:1000; after the polystyrene and the core-shell nano-cadmium selenide nano-powders coated with zinc sulfide are fully dissolved, the two mixed solvents are mixed and stirred for more than 6 hours; then the mixed solution is poured into 75 mL of isopropyl alcohol solvent, and the mixture of polystyrene and the core-shell nano-cadmium selenide nano-powders coated with zinc sulfide will be extracted to obtain the polystyrene-based nano-composite insulation materials; the extracted polystyrene-based nano-composite insulation materials are poured into a ceramic funnel for filtration. The filtrate needs to be left standing in a fume hood for 4 days to ensure that most of the organic solvents are volatilized. Then the polystyrene-based nano-composite insulation materials are introduced into a mold for the first hot pressing to extrude the air bubbles therein. The hot pressing temperature is 180 °C, the pressure is 2 tons, and the hot pressing time is 8 minutes. The polystyrene-based nano-composite insulation obtained after hot pressing needs to be left standing in a vacuum drying oven at 60 °C for 3 days to completely filter out the organic solvent residues; finally, the polystyrene-based nano-composite insulation is hot pressed again into the required shape.

[0030] As attached Figure 5As shown, the characterization of the mixing effect of polystyrene and nano powder is to determine the dispersion of cadmium selenide powder coated with zinc sulfide in the polystyrene matrix. The mixing effect of polystyrene and cadmium selenide nano powder coated with zinc sulfide can be observed through a transmission electron microscope. The cadmium selenide nano powder coated with zinc sulfide is distributed in the polystyrene matrix in the form of clusters, and the average diameter of the clusters is about 20 nm.

[0031] As shown in the appendix Figure 6 As shown, the analysis of the in vivo charge accumulation of the polystyrene-based nano-composite insulating material is to measure the internal space charge distribution of the polystyrene-based nano-composite insulation obtained in the present invention under a DC electric field on the basis of existing space charge measurement techniques. It mainly includes: a pulse power supply 1, a polystyrene-based nano-composite insulation 2, a 50 Ω resistor 3, a coupling capacitor 4, a high-voltage electrode 5, a PVDF-TrEF film 6, a high-voltage resistor 7, a DC power supply 8, a ground electrode 9, an amplifier 10, and an oscilloscope 11; where: one end of the pulse power supply 1 is connected to one end of the 50 Ω resistor 3 and the high-voltage capacitor 10, and the other end is grounded, and it can emit a pulse with an amplitude of 400 V and a pulse width of 20 ns; the other end of the 50 Ω resistor 9 is grounded; the other end of the high-voltage capacitor 4 is connected to one end of the high-voltage electrode 5 and the high-voltage resistor 7. The other end of the high-voltage electrode 5 is pressed on one side of the polystyrene-based nano-composite insulating material 2; the other side of the polystyrene-based nano-composite insulating material 2 is pressed on one side of the ground electrode 15; the other side of the ground electrode 15 is in close contact with one side of the PVDF-TrEF film 6; the other side of the PVDF-TrEF film 6 is connected to the output end of the amplifier 10, and a layer of metal is plated on both sides of the PVDF-TrEF film as an electrode; the other end of the high-voltage resistor 7 is connected to the high-voltage output end of the DC power supply; the output of the amplifier 10 is connected to the input of the oscilloscope 11. Before measurement, select the polystyrene used in the preparation of the polystyrene-based nano-composite insulation, and hot-press it at a temperature of 180 °C and a pressure of 2 tons for 8 minutes to make a pure polystyrene sample as a standard sample; the polystyrene-based nano-composite insulation obtained by the preparation of the polystyrene-based nano-composite insulation is used as the sample to be measured, and the in vivo space charge density curves of the standard sample and the sample to be measured are measured respectively under a DC voltage with an applied electric field strength of +50 kV / mm. The charge quantity Q in the sample and the space charge density ρ satisfy the following relationship:

[0032]

[0033] In the formula: S is the area of the high-voltage electrode 5, with the unit of m 2 ; x is the distance from the contact surface between the ground electrode 9 and the polystyrene-based nano-composite insulation 8 as the starting point to the high-voltage electrode 5; Δ x is the depth of the injected charge inside the sample to be measured.

[0034] As shown in the appendixFigure 7 and appendix Figure 8 , according to the measured space charge density in the sample, the area of the high-voltage electrode 5 is 50 mm 2 , Δ x is about 0.130 mm, and it can be calculated that the charge amount in the body of a pure polystyrene sample with a volume of 6.6 mm 3 is about 0.9 μC after applying a DC electric field of +50 kV / mm for 1 hour, about 1.1 μC after 3 hours, and about 3.0 μC after 12 hours. That is, with the increase of the DC voltage application time, charges will significantly accumulate in pure polystyrene. For the polystyrene-based nanocomposite insulating material added with core-shell nano-zinc sulfide-coated cadmium selenide nano-powder, after applying a DC electric field of +50 kV / mm for 1 hour, 3 hours, and 12 hours, the charge amounts in the body are about 0.3 μC, 0.3 μC, and 0.45 μC respectively. It can be concluded that compared with pure polystyrene, for the polystyrene-based nanocomposite insulating material added with core-shell nano-zinc sulfide-coated cadmium selenide nano-powder, under a high DC electric field intensity, the space charge amount accumulated in the body after 12 h of pressurization is only 0.45 μC, which is still significantly lower than the space charge amount in the body of pure polystyrene after 1 hour under the same electric field. It can be confirmed that the method involved in this invention patent can effectively reduce the accumulation amount of volume charges in the polystyrene-based nanocomposite insulating material under the action of an electric field.

Claims

1. A polystyrene-based nanocomposite insulating material with a low volume charge accumulation amount, characterized in that: in the given polystyrene-based nanocomposite insulating material, cadmium selenide nanoparticles coated with zinc sulfide exist in the form of clusters with a diameter of 20 nm, and the volume charge amount in the body is less than 0.45 μC under a +50 kV / mm DC electric field; The specific preparation process is as follows: Prepare nano-core cadmium selenide nanoparticles, coat zinc sulfide on the cadmium selenide nanoparticles to obtain core-shell nano-zinc sulfide-coated cadmium selenide nanoparticles, measure the diameter and shape of the core-shell nano-zinc sulfide-coated cadmium selenide nanoparticles, and determine that the diameter is 4.75 nm and the shape is spherical; Dissolve the core-shell nano-zinc sulfide-coated cadmium selenide nanoparticles and polystyrene in dichloromethane respectively and mix them to obtain a polystyrene-based nanocomposite insulating material containing 0.1 wt% zinc sulfide, and measure that the core-shell nano-zinc sulfide-coated cadmium selenide nanoparticles exist in the form of clusters with an average diameter of 20 nm in polystyrene; The preparation of the core-shell nano-zinc sulfide-coated cadmium selenide nanoparticles: In an argon atmosphere, mix zinc oxide powder, octadecenoic acid solution and octadecene solution with a molar ratio of 1.3:3:140, mix sulfur powder, butyltriphenylphosphine and octadecene solution with a molar ratio of 1:1.8:140, and the mixing temperature is 320 °C; Mix the two mixtures, add cadmium selenide nanoparticles, and cool to 250 °C to grow zinc sulfide crystals on the cadmium selenide; After the mixed solution containing zinc sulfide-coated cadmium selenide crystals is cooled to 40 °C, mix it with chloroform, and after centrifugation, extract it with methanol or acetone to obtain spherical core-shell nano-zinc sulfide-coated cadmium selenide nanoparticles.

2. A polystyrene-based nanocomposite insulating material with a low volume charge accumulation amount according to claim 1, characterized in that, The preparation of the nano-core cadmium selenide nanoparticles is specifically as follows: In an argon atmosphere, mix cadmium oxide powder, octadecenoic acid solution and octadecene solution with a molar ratio of 1:3:140, mix selenium powder, butyltriphenylphosphine and octadecene solution with a molar ratio of 1:1.1:140, and the mixing temperature is 320 °C; Mix the two mixtures and cool to 290 °C to grow cadmium selenide crystals; After the mixed solution containing cadmium selenide crystals is cooled to 40 °C, mix it with chloroform, and after centrifugation, extract it with methanol or acetone to obtain spherical cadmium selenide nanoparticles.

3. A polystyrene-based nanocomposite insulating material with a low volume charge accumulation amount according to claim 2, characterized in that, Through the measurement of the nano-particle diameter and the morphological characterization of the core-shell nano-zinc sulfide-coated cadmium selenide nanoparticles, the diameter of the cadmium selenide nanoparticles is 4.77 nm, the diameter of the zinc sulfide-coated cadmium selenide nanoparticles is 4.75 nm, and both the cadmium selenide nanoparticles and the zinc sulfide-coated cadmium selenide nanoparticles are spherical.

4. A polystyrene-based nanocomposite insulating material with a low volume charge accumulation amount according to claim 1, characterized in that, Preparation of the polystyrene-based nanocomposite insulating material: Using polystyrene as the matrix material, dissolve polystyrene in dichloromethane at room temperature with a mass ratio of 1:6.5; dissolve cadmium selenide nanoparticles coated with zinc sulfide in dichloromethane with a mass ratio of 1:1.1; fully mix the two mixtures, perform extraction with isopropanol and then filter to obtain a mixture of polystyrene and cadmium selenide nanoparticles coated with zinc sulfide, namely the polystyrene-based nanocomposite insulating material, and the mass ratio of cadmium selenide nanoparticles coated with zinc sulfide to polystyrene is 1:1000; hot press the polystyrene-based nanocomposite insulating material into shape.

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