Preparation method of polypropylene-based bismuth shielding gamma-ray composite material with uniformly dispersed shielding filler

Abstract

The invention discloses a preparation method of a polypropylene-based bismuth gamma-ray shielding composite material with uniformly dispersed shielding filler, and belongs to the field of ionizing radiation shielding materials. According to the invention, the problems of poor compatibility between a PP matrix and bismuth oxide, high density and insufficient mechanical property and thermal stability are solved. The method comprises the following steps: carrying out melt blending on polypropylene, the flexibilizer, the compatilizer and bismuth oxide particles, and carrying out hot pressing or critical CO2 foaming. The polypropylene-based bismuth composite material which has a micro-branching degree characteristic, uniform dispersion of bismuth oxide particles, high thermal stability and good gamma-ray shielding performance and mechanical property is prepared by a melt blending method; the composite material with certain shielding performance and remarkable lightweight advantage is obtained through a critical CO2 foaming method. The prepared polypropylene-based bismuth shielding gamma-ray composite material with uniformly dispersed shielding filler is applied to the fields of industrial detection, medical health and space ionizing radiation protection.

Description

Technical Field

[0001] This invention belongs to the field of ionizing radiation shielding materials. Background Technology

[0002] Gamma rays, as a high-energy electromagnetic wave, are widely used in medical diagnostics, nuclear industry, radiation therapy, and other fields. However, excessive exposure can cause serious harm to human tissues and the environment. Therefore, highly efficient gamma-ray shielding materials have become a key need in these fields. Traditional gamma-ray shielding materials mostly use lead as the core component, achieving their shielding effect through its high density and high atomic number. However, lead is highly toxic, and its production, use, and disposal can easily cause soil and water pollution, harming the ecological environment and human health. Its application has gradually been restricted.

[0003] Composite materials prepared by melt blending lead-free heavy metals as fillers with polymer materials as the matrix have broad application prospects in the field of gamma-ray shielding. Currently, commonly used heavy metal oxides include Gd₂O₃, WO₃, and Bi₂O₃. Among them, Bi₂O₃ meets the requirements of being lead-free, environmentally friendly, and contains bismuth (Z₂O₃), an element with a high atomic number. Bi =83>Z Pb =82). Polypropylene (PP), as a common polymer matrix, has attracted widespread attention due to its low cost and stable chemical properties. However, in practical applications, there are many problems when preparing shielding composite materials using PP as the matrix and adding bismuth oxide metal particles: on the one hand, the metal particles have poor compatibility with the PP matrix, which easily leads to particle agglomeration and affects the mechanical and shielding properties of the composite material; on the other hand, to achieve the ideal shielding effect, a large number of metal particles are often required, resulting in a significant increase in the density of the composite material and losing the lightweight advantage of polymer materials; in addition, the thermal stability of the composite material also needs to be further improved to meet the requirements of use in complex environments. Therefore, developing a lead-free, compatible, and lightweight polypropylene-based bismuth shielding γ-ray composite material with excellent mechanical properties and thermal stability is the key to solving the current technological bottlenecks and has important practical application value. Summary of the Invention

[0004] This invention solves the problems of poor compatibility between PP matrix and bismuth oxide, high density, and insufficient mechanical properties and thermal stability, and provides a method for preparing polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler.

[0005] A method for preparing a polypropylene-based bismuth-based gamma-ray shielding composite material with uniformly dispersed shielding filler, the method specifically comprising the following steps:

[0006] Polypropylene, toughening agent, compatibilizer and bismuth oxide particles were placed in a torque rheometer and melt-blended for 5 min to 20 min at a rotation speed of 30 rpm to 90 rpm and a temperature of 160℃ to 200℃. The resulting polypropylene-based bismuth composite material particles were then extruded and hot-pressed in a flat vulcanizing machine to obtain a lead-free polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation.

[0007] A method for preparing a polypropylene-based bismuth-based gamma-ray shielding composite material with uniformly dispersed shielding filler, the method specifically comprising the following steps:

[0008] Polypropylene, toughening agent, compatibilizer, and bismuth oxide particles were placed in a torque rheometer and melt-blended for 5 to 20 minutes at a rotation speed of 30 to 90 rpm and a temperature of 160 to 200°C. The resulting product was then extruded to obtain polypropylene-based bismuth composite material particles. These particles were then placed in a supercritical CO2 foaming device, infused with liquid CO2, and the temperature was raised to 160 to 205°C. A pressure of 5 to 25 MPa was applied and maintained for 20 to 60 minutes to obtain a lightweight polypropylene-based bismuth composite material with uniformly dispersed shielding filler.

[0009] Furthermore, the composition is as follows: 55-70 parts by weight of polypropylene, 0-10 parts by weight of toughening agent, 0-5 parts by weight of compatibilizer, and 15-45 parts by weight of bismuth oxide particles.

[0010] Furthermore, the composition is as follows: 60-70 parts by weight of polypropylene, 0-5 parts by weight of toughening agent, 0-5 parts by weight of compatibilizer, and 20-40 parts by weight of bismuth oxide particles.

[0011] Furthermore, the toughening agent is one or a mixture of several of the following: polybutadiene latex, styrene-butadiene rubber, nitrile rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer, styrene-ethylene-butene-styrene block copolymer, and acrylonitrile-butadiene-styrene copolymer.

[0012] Furthermore, the compatibilizer is one or a mixture of several of the following: acrylamide, polypropylene grafted maleic anhydride, glycidyl methacrylate, styrene-maleic anhydride copolymer, γ-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0013] The beneficial effects of this invention are:

[0014] This invention innovatively prepares a polypropylene-based bismuth shielding gamma-ray composite material with a microbranched structure and significant lightweight advantages by melt blending, hot pressing, and supercritical CO2 foaming of polypropylene, toughening agent, compatibilizer, and bismuth oxide particles. This solves the problems of poor compatibility, mechanical properties, thermal stability, and high density of polypropylene composites with metal particles. The method of this invention is not only simple to operate, but also enables the polypropylene-based bismuth composite material to possess a microbranched structure, uniform bismuth oxide particle dispersion, high thermal stability, good gamma-ray shielding performance and mechanical properties, while maintaining certain shielding performance and significant lightweight advantages. It can be used in industrial testing, medical and health, and space ionizing radiation protection fields.

[0015] The mass ratio of polypropylene, toughening agent, compatibilizer, and bismuth oxide particles specified in this invention enables polypropylene-based bismuth composite materials to have a good microbranched structure, high thermal stability, good γ-ray shielding performance, and good mechanical properties. The melt blending process parameters can ensure that bismuth oxide particles are uniformly dispersed in the polypropylene matrix. The foaming process gives the composite material a significant lightweight advantage while maintaining a certain shielding performance.

[0016] The polypropylene-based bismuth shielding gamma-ray composite material with uniformly dispersed shielding filler prepared by this invention can be used in industrial testing, medical and health care, and space ionizing radiation protection. Attached Figure Description

[0017] Figure 1 The flowcharts are for the preparation of lead-free polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler in Specific Implementation Method 1 and the preparation of lightweight polypropylene-based bismuth composite material with uniformly dispersed shielding filler in Specific Implementation Method 2.

[0018] Figure 2 The complex viscosity-frequency curves are shown for the polypropylene-based bismuth shielding γ-ray composite materials prepared in Examples 1, 3 and 4.

[0019] Figure 3 The storage modulus-frequency curves are shown for the polypropylene-based bismuth shielding γ-ray composite materials prepared in Examples 2, 3 and 4.

[0020] Figure 4 This is a comparison chart of the LCBI values ​​of the polypropylene-based bismuth shielding γ-ray composite materials prepared in Examples 2, 3, and 4.

[0021] Figure 5 The image shows the microstructure of the polypropylene-based bismuth-shielded γ-ray composite material prepared in Example 2.

[0022] Figure 6 A comparison of the impact strength values ​​of the polypropylene-based bismuth shielding γ-ray composite materials prepared in Example 1 and Example 2;

[0023] Figure 7 A comparison of the linear attenuation coefficient values ​​of the polypropylene-based bismuth shielding γ-ray composite materials prepared in Example 1 and Example 2;

[0024] Figure 8 This is a comparison chart of the porosity values ​​of the polypropylene-based bismuth shielding γ-ray composite materials prepared in Examples 5, 6, and 7.

[0025] Figure 9 The image shows the microstructure of the polypropylene-based bismuth-shielded γ-ray composite material prepared in Example 5.

[0026] Figure 10 The image shows the microstructure of the polypropylene-based bismuth-shielded γ-ray composite material prepared in Example 7.

[0027] Figure 11 A comparison of the linear attenuation coefficient values ​​of the polypropylene-based bismuth shielding γ-ray composite materials prepared in Example 5 and Example 7;

[0028] Figure 12 The graph shows a comparison of the shielding efficiency values ​​of the polypropylene-based bismuth shielding γ-ray composite materials prepared in Examples 5, 6 and 7. Detailed Implementation

[0029] Specific Implementation Method 1: This implementation method describes a method for preparing a polypropylene-based bismuth-based gamma-ray shielding composite material with uniformly dispersed shielding filler, specifically following these steps:

[0030] Polypropylene, toughening agent, compatibilizer and bismuth oxide particles were placed in a torque rheometer and melt-blended for 5 min to 20 min at a rotation speed of 30 rpm to 90 rpm and a temperature of 160℃ to 200℃. The resulting polypropylene-based bismuth composite material particles were then extruded and hot-pressed in a flat vulcanizing machine to obtain a lead-free polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation.

[0031] Specific Implementation Method Two: This implementation method provides a method for preparing a polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, specifically following these steps:

[0032] Polypropylene, toughening agent, compatibilizer, and bismuth oxide particles were placed in a torque rheometer and melt-blended for 5 to 20 minutes at a rotation speed of 30 to 90 rpm and a temperature of 160 to 200°C. The resulting product was then extruded to obtain polypropylene-based bismuth composite material particles. These particles were then placed in a supercritical CO2 foaming device, infused with liquid CO2, and the temperature was raised to 160 to 205°C. A pressure of 5 to 25 MPa was applied and maintained for 20 to 60 minutes to obtain a lightweight polypropylene-based bismuth composite material with uniformly dispersed shielding filler.

[0033] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the polypropylene content is 55-70 parts by weight, the toughening agent is 0-10 parts, the compatibilizer is 0-5 parts, and the bismuth oxide particles are 15-45 parts. Everything else is the same as in Specific Implementation Method One or Two.

[0034] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the polypropylene content is 60-70 parts by weight, the toughening agent is 0-5 parts, the compatibilizer is 0-5 parts, and the bismuth oxide particles are 20-40 parts. Everything else is the same as in Specific Implementation Methods One to Three.

[0035] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the toughening agent is one or a mixture of several of the following: polybutadiene latex, styrene-butadiene rubber, nitrile rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer, styrene-ethylene-butene-styrene block copolymer, and acrylonitrile-butadiene-styrene copolymer. Everything else is the same as in Specific Implementation Methods One to Four.

[0036] Specific Embodiment Six: This embodiment differs from Specific Embodiments One to Five in that the compatibilizer is one or a mixture of several of the following: acrylamide, polypropylene grafted maleic anhydride, glycidyl methacrylate, styrene-maleic anhydride copolymer, γ-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane. Everything else is the same as in Specific Embodiments One to Five.

[0037] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the melt blending is performed for 5 to 20 minutes at a rotation speed of 40 to 70 rpm and a temperature of 160 to 200°C. Everything else is the same as in Specific Implementation Methods One to Six.

[0038] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the mixture is melt-blended for 10 minutes at a rotation speed of 60 rpm and a temperature of 185°C. Everything else is the same as in Specific Implementation Methods One to Seven.

[0039] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One through Eight in that: liquid CO2 is introduced into the supercritical CO2 foaming device, the temperature is raised to 165℃~185℃, the pressure is applied to 10Pa~20 MPa, and maintained for 20min~40min. Everything else is the same as in Specific Implementation Methods One through Eight.

[0040] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One through Nine in that: liquid CO2 is introduced into the supercritical CO2 foaming device, the temperature is raised to 175~180℃, the pressure is applied to 15MPa, and maintained for 30 minutes. Everything else is the same as in Specific Implementation Methods One through Nine.

[0041] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

[0042] Example 1:

[0043] This embodiment describes a method for preparing a lead-free, uniformly dispersed polypropylene-based bismuth-shielded gamma-ray composite material, which is carried out according to the following steps:

[0044] 70 parts by mass of polypropylene and 30 parts by mass of bismuth oxide particles were placed in a torque rheometer and melt-blended for 10 min at a speed of 60 rpm and a temperature of 185 °C. The resulting polypropylene-based bismuth composite material particles were then extruded and hot-pressed in a flat vulcanizing machine to obtain a lead-free polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation.

[0045] Example 2:

[0046] This embodiment describes a method for preparing a lead-free, uniformly dispersed polypropylene-based bismuth-shielded gamma-ray composite material, which is carried out according to the following steps:

[0047] 60 parts by weight of polypropylene, 5 parts by weight of polybutadiene nano-rubber, 5 parts by weight of acrylamide and 30 parts by weight of bismuth oxide particles were placed in a torque rheometer and melt-blended for 10 min at a speed of 60 rpm and a temperature of 185℃. The resulting polypropylene-based bismuth composite material particles were then extruded and hot-pressed in a flat vulcanizing machine to obtain a lead-free polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation.

[0048] Example 3:

[0049] This embodiment describes a method for preparing a lead-free, uniformly dispersed polypropylene-based bismuth-shielded gamma-ray composite material, which is carried out according to the following steps:

[0050] 60 parts by weight of polypropylene, 5 parts by weight of polybutadiene nano-rubber, 5 parts by weight of γ-aminopropyltriethoxysilane and 30 parts by weight of bismuth oxide particles were placed in a torque rheometer and melt-blended for 10 minutes at a speed of 60 rpm and a temperature of 185°C. The resulting polypropylene-based bismuth composite material particles were then extruded and hot-pressed in a flat vulcanizing machine to obtain a lead-free polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation.

[0051] Example 4:

[0052] This embodiment describes a method for preparing a lead-free, uniformly dispersed polypropylene-based bismuth-shielded gamma-ray composite material, which is carried out according to the following steps:

[0053] 60 parts by weight of polypropylene, 5 parts by weight of polybutadiene nano-rubber, 5 parts by weight of polypropylene grafted maleic anhydride, and 30 parts by weight of bismuth oxide particles were placed in a torque rheometer and melt-blended for 10 minutes at a speed of 60 rpm and a temperature of 185°C. The resulting polypropylene-based bismuth composite material particles were then extruded and hot-pressed in a flat vulcanizing machine to obtain a lead-free polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation.

[0054] Example 5:

[0055] This embodiment describes a method for preparing a lightweight, uniformly dispersed polypropylene-based bismuth-shielded γ-ray composite material, which is carried out according to the following steps:

[0056] 65 parts by weight of polypropylene, 5 parts by weight of polybutadiene nano-rubber, and 30 parts by weight of bismuth oxide particles were placed in a torque rheometer and melt-blended for 10 min at a rotation speed of 60 rpm and a temperature of 185 °C. The resulting polypropylene-based bismuth composite material particles were then extruded and placed in a supercritical CO2 foaming device. Liquid CO2 was introduced, the temperature was raised to 175.5 °C, and the pressure was applied to 15 MPa and maintained for 30 min. This yielded a lightweight polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation process.

[0057] Example 6:

[0058] This embodiment describes a method for preparing a lightweight, uniformly dispersed polypropylene-based bismuth-shielded γ-ray composite material, which is carried out according to the following steps:

[0059] 70 parts by mass of polypropylene and 30 parts by mass of bismuth oxide particles were placed in a torque rheometer and melt-blended for 10 min at a rotation speed of 60 rpm and a temperature of 185 °C. The resulting polypropylene-based bismuth composite material particles were then extruded and placed in a supercritical CO2 foaming device. Liquid CO2 was introduced, the temperature was raised to 175.5 °C, and the pressure was applied to 15 MPa and maintained for 30 min. This yielded a lightweight polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation process.

[0060] Example 7:

[0061] This embodiment describes a method for preparing a lightweight, uniformly dispersed polypropylene-based bismuth-shielded γ-ray composite material, which is carried out according to the following steps:

[0062] 60 parts by weight of polypropylene, 5 parts by weight of polybutadiene nano-rubber, 5 parts by weight of acrylamide, and 30 parts by weight of bismuth oxide particles were placed in a torque rheometer and melt-blended for 10 min at a rotation speed of 60 rpm and a temperature of 185 °C. The resulting polypropylene-based bismuth composite material particles were then extruded and placed in a supercritical CO2 foaming device. Liquid CO2 was introduced, the temperature was raised to 175.5 °C, and the pressure was applied to 15 MPa and maintained for 30 min to obtain a lightweight polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler. The preparation was then complete.

[0063] Figure 2 The graphs show the complex viscosity-frequency curves of the polypropylene-based bismuth shielding γ-ray composite materials prepared in Examples 1, 3 and 4. The complex viscosity values ​​of Examples 3 and 4 are higher than those of Example 1, and the degree of restriction on the PP matrix chains is also enhanced.

[0064] Figure 3 The graphs show the storage modulus-frequency curves of the polypropylene-based bismuth shielding γ-ray composite materials prepared in Examples 2, 3 and 4. The polypropylene-based bismuth shielding γ-ray composite material prepared in Example 2 has the highest storage modulus curve, stronger intermolecular forces, and better elasticity.

[0065] Figure 4 This is a comparison chart of the LCBI values ​​of the polypropylene-based bismuth-shielded gamma-ray composite materials prepared in Examples 2, 3, and 4. The chart shows that the polypropylene-based bismuth-shielded gamma-ray composite material prepared in Example 2 has the highest degree of branching and the best interfacial bonding between its components.

[0066] Figure 5The image shows the microstructure of the polypropylene-based bismuth-shielded γ-ray composite material prepared in Example 2. As can be seen from the image, the interface between the bismuth oxide particles and the matrix in the polypropylene-based bismuth-shielded γ-ray composite material prepared in Example 2 is smooth, and the bismuth oxide particles are embedded in the matrix, confirming that this improves the compatibility between bismuth oxide and the PP matrix.

[0067] Figure 6 This is a comparison of the impact strength values ​​of the polypropylene-based bismuth-shielded gamma-ray composite materials prepared in Example 1 and Example 2. As shown in the figure, the impact strength value of the polypropylene-based bismuth-shielded gamma-ray composite material prepared in Example 2 is higher than that of Example 1, and the composite material in Example 2 also exhibits the best stiffness and toughness.

[0068] Figure 7 This is a comparison of the linear attenuation coefficients of the polypropylene-based bismuth-shielded γ-ray composite materials prepared in Example 1 and Example 2. The figure shows that γ-rays are more likely to be absorbed per unit distance in the composite material of Example 2, resulting in a larger linear attenuation coefficient.

[0069] Figure 8 The figures show the porosity values ​​of the polypropylene-based bismuth-shielded γ-ray composite materials prepared in Examples 5, 6, and 7. As can be seen from the figures, the porosity of the lightweight polypropylene-based bismuth composite materials prepared in Examples 5, 6, and 7 reached approximately 80%, with the lightweight composite material in Example 7 exhibiting the highest porosity.

[0070] Figure 9 The image shows the microstructure of the polypropylene-based bismuth-shielded γ-ray composite material prepared in Example 5. As can be seen from the image, the bismuth oxide particles in the lightweight composite material of Example 5 are severely agglomerated, and the interfacial bonding between the bismuth oxide and the PP matrix is ​​weak.

[0071] Figure 10 The image shows the microstructure of the polypropylene-based bismuth-shielded γ-ray composite material prepared in Example 7. As can be seen from the image, the number of exposed bismuth oxide particles in the lightweight composite material of Example 7 is significantly reduced, and the bismuth oxide particles are effectively embedded in the PP matrix, enhancing the interfacial bonding between the bismuth oxide dispersion and the PP matrix.

[0072] Figure 11 The figures show the linear attenuation coefficients of the polypropylene-based bismuth-shielded γ-ray composite materials prepared in Examples 5 and 7. As can be seen from the figures, γ-rays are more likely to be absorbed per unit distance in the composite material of Example 7, resulting in a larger linear attenuation coefficient.

[0073] Figure 12 This is a comparison of the shielding efficiency values ​​of the polypropylene-based bismuth gamma-ray shielding composite materials prepared in Examples 5, 6, and 7. The figure shows that the lightweight composite material prepared in Example 7 has the highest shielding efficiency value and provides better gamma-ray shielding.

Claims

1. A method for preparing a polypropylene-based bismuth-shielded γ-ray shielding composite material with uniformly dispersed shielding filler, characterized in that... This method is specifically carried out in the following steps: Polypropylene, toughening agent, compatibilizer and bismuth oxide particles were placed in a torque rheometer and melt-blended for 5 min to 20 min at a rotation speed of 30 rpm to 90 rpm and a temperature of 160℃ to 200℃. The resulting polypropylene-based bismuth composite material particles were then extruded and hot-pressed in a flat vulcanizing machine to obtain a lead-free polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler, thus completing the preparation.

2. A method for preparing a polypropylene-based bismuth-shielded γ-ray shielding composite material with uniformly dispersed shielding filler, characterized in that... This method is specifically carried out in the following steps: Polypropylene, toughening agent, compatibilizer, and bismuth oxide particles were placed in a torque rheometer and melt-blended for 5 to 20 minutes at a rotation speed of 30 to 90 rpm and a temperature of 160 to 200°C. The resulting product was then extruded to obtain polypropylene-based bismuth composite material particles. These particles were then placed in a supercritical CO2 foaming device, infused with liquid CO2, and the temperature was raised to 160 to 205°C. A pressure of 5 to 25 MPa was applied and maintained for 20 to 60 minutes to obtain a lightweight polypropylene-based bismuth composite material with uniformly dispersed shielding filler.

3. A method for preparing a polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler according to claim 1 or 2, characterized in that... The components are polypropylene (55-70 parts by weight), toughening agent (0-10 parts by weight), compatibilizer (0-5 parts by weight), and bismuth oxide particles (15-45 parts by weight).

4. The method for preparing a polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler according to claim 3, characterized in that... The components are: 60-70 parts by weight of polypropylene, 0-5 parts by weight of toughening agent, 0-5 parts by weight of compatibilizer, and 20-40 parts by weight of bismuth oxide particles.

5. A method for preparing a polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler according to claim 1 or 2, characterized in that... The toughening agent is one or a mixture of several of the following: polybutadiene latex, styrene-butadiene rubber, nitrile rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer, styrene-ethylene-butene-styrene block copolymer, and acrylonitrile-butadiene-styrene copolymer.

6. A method for preparing a polypropylene-based bismuth-shielded γ-ray composite material with uniformly dispersed shielding filler according to claim 1 or 2, characterized in that... The compatibilizer is one or a mixture of several of the following: acrylamide, polypropylene grafted maleic anhydride, glycidyl methacrylate, styrene-maleic anhydride copolymer, γ-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

7. A method for preparing a polypropylene-based bismuth-shielded γ-ray composite material with uniformly dispersed shielding filler according to claim 1 or 2, characterized in that... Melt blend for 5 min to 20 min at a rotation speed of 40 rpm to 70 rpm and a temperature of 160℃ to 200℃.

8. The method for preparing a polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler according to claim 7, characterized in that... Melt blend for 10 minutes at a rotation speed of 60 rpm and a temperature of 185°C.

9. The method for preparing a polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler according to claim 2, characterized in that... Liquid CO2 is introduced into the supercritical CO2 foaming device, the temperature is raised to 165℃~185℃, the pressure is applied to 10Pa~20 MPa, and maintained for 20min~40min.

10. The method for preparing a polypropylene-based bismuth shielding γ-ray composite material with uniformly dispersed shielding filler according to claim 9, characterized in that... Liquid CO2 was introduced into the supercritical CO2 foaming device, the temperature was raised to 175~180℃, the pressure was applied to 15MPa, and maintained for 30 min.

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