Core-satellite structure inorganic filler reinforced rubber-based functional composites and methods of making the same

Abstract

The application provides a kind of core-satellite structure inorganic filler reinforced rubber-based functional composite material and its preparation method, belongs to high polymer functional composite material technical field. With the surface aminated micron class spherical tungsten powder and the surface carboxylated nanometer spherical bismuth oxide as raw material, through electrostatic self-assembly and amidation heat treatment, W@Bi2O3 core-satellite structure composite powder is obtained, which is chemically combined by amide bond, and is mixed with natural rubber to prepare X / gamma ray shielding functional rubber layer;With flaky hexagonal boron nitride as filler and natural rubber mixing to prepare neutron shielding functional rubber layer;The neutron shielding functional rubber layer is placed on both sides of the X / gamma ray shielding functional rubber layer, and after superimposition, co-vulcanization integrated molding is carried out, to obtain a three-layer functional sequence flexible functional composite material. By such arrangement, the performance degradation defects caused by the sedimentation segregation of high specific gravity components and uneven distribution of fillers in the traditional blending scheme are effectively avoided, and the obtained material has bidirectional equivalent shielding capability of neutron and X / gamma ray.

Description

Technical Field

[0001] This application relates to the field of polymer functional composite materials technology, specifically to a rubber-based functional composite material reinforced with inorganic fillers in a nuclear-satellite structure and its preparation method. This rubber-based functional composite material can simultaneously achieve efficient shielding of X / γ rays and neutrons, and is suitable for fields such as medical radiation protection. Background Technology

[0002] In the field of functional polymer composites, inorganic filler-reinforced rubber matrix materials are an important way to achieve multifunctionality. However, they generally suffer from three major common technical bottlenecks: First, the density difference between high-density inorganic fillers and low-density rubber matrices is significant, easily leading to filler sedimentation and segregation during mixing and vulcanization, resulting in uneven spatial distribution of material properties. Second, when multiple functional fillers are blended, the large differences in density and morphology between different components easily lead to macroscopic sedimentation and stratification as well as micro-agglomeration. This not only causes uneven spatial distribution of shielding performance but also degrades the material's processing fluidity and mechanical properties, making it difficult to achieve the theoretically optimal comprehensive performance with the same total filler content. Third, multilayer composite structures often adopt a process of separate molding followed by bonding, and the stress concentration at the interface easily leads to delamination, seriously affecting service life and reliability. Especially in radiation fields where neutrons and X / γ rays coexist, such as nuclear energy, radiation medicine, and space exploration, shielding materials need to combine multifunctional synergistic shielding, lightweight flexibility, and mechanical reliability, making the above common problems particularly prominent.

[0003] In the existing technology, there are mainly the following technical routes: 1) Blending heavy metal powders such as tungsten and bismuth oxide with boron-based neutron absorbers into a polymer matrix; this scheme can improve shielding performance by increasing the total filling amount, but there are problems such as high-density components settling and low-density components floating, resulting in uneven spatial distribution of shielding performance, and filler agglomeration is prone to stress concentration and mechanical property deterioration, making it difficult to balance shielding uniformity and reliability; 2) Molding different functional layers separately and then bonding them together; although this scheme can avoid functional interference between fillers in the same layer, it is prone to introducing delamination risks due to interface stress concentration.

[0004] Therefore, how to achieve the partitioned deployment of multiple functions in a rubber matrix without interference, while fundamentally solving the problems of filler segregation and agglomeration and weak interfacial bonding, is a technical bottleneck that urgently needs to be overcome in the field of rubber-based functional composite materials. Summary of the Invention

[0005] In view of the above-mentioned technical problems existing in the prior art, this application provides a rubber-based functional composite material reinforced with a core-satellite structure inorganic filler and its preparation method. This preparation method solves the problems of multi-filler gravity segregation, weak interfacial bonding, and easy delamination in traditional rubber-based composite materials through a functionally ordered layered structure and a chemically bonded core-satellite filler design. The resulting rubber-based functional composite material possesses both bidirectional radiation shielding capability and excellent flexibility.

[0006] In a first aspect, this application provides a method for preparing a rubber-based functional composite material reinforced with inorganic fillers for a nuclear-satellite structure, comprising the following steps: S1. Micron-sized spherical tungsten powder is subjected to surface oxidation activation treatment and amination treatment, and nano-sized spherical bismuth oxide powder is subjected to surface carboxylation treatment. Through electrostatic self-assembly and amidation heat treatment, W@Bi2O3 core-satellite structure composite powder with amide bond chemical bonding is obtained. S2. The W@Bi2O3 core-satellite structure composite powder is mixed with a natural rubber matrix, and vulcanizing compounding agent and antioxidant are added to obtain X / γ ray shielding compound; S3. After surface pretreatment, the flake-shaped hexagonal boron nitride powder is mixed with natural rubber matrix, and vulcanizing compounding agent and antioxidant are added to obtain neutron shielding compound; S4. Using the neutron shielding compound as the upper and lower layers and the X / γ ray shielding compound as the middle layer, the layers are stacked sequentially and then co-vulcanized and hot-pressed to obtain a rubber-based functional composite material reinforced with inorganic fillers of a nuclear-satellite structure.

[0007] Further, in step S1, the process flow of surface oxidation activation and amination treatment is as follows: micron-sized spherical tungsten powder is added to hydrogen peroxide solution, stirred at room temperature, and subjected to intermittent ultrasonic treatment for surface oxidation activation. After a uniform hydrated tungsten oxide thin layer is formed on the surface, it is washed with deionized water until neutral, and then replaced with anhydrous ethanol to obtain activated tungsten powder rich in hydroxyl grafting sites; silane coupling agent KH550, deionized water, and anhydrous ethanol are mixed at a mass-volume ratio of 1g:(1-5)mL:(20-90)mL, the pH is adjusted to 4-5 with acetic acid, and pre-hydrolyzed at room temperature for 20-40 min until the solution is transparent to obtain KH550 pre-hydrolyzed solution; wherein, the particle size of the micron-sized spherical tungsten powder is 1-5 mm. μm; the mass fraction of the hydrogen peroxide solution is 0.5%–1.0%, the mass-volume ratio of tungsten powder to hydrogen peroxide solution is 1g:(2–5)mL, and the surface oxidation activation treatment time is 0.5–1h; the amount of silane coupling agent KH550 used is 0.5%–2.0% of the mass of tungsten powder; Subsequently, the activated tungsten powder was dispersed in anhydrous ethanol, and the KH550 pre-hydrolyzed solution was added. The mixture was stirred and reacted at 50–70 °C for 3–5 h. The reaction product was thoroughly washed with anhydrous ethanol to remove free silanes, and then redispersed in anhydrous ethanol. The pH was adjusted to 4.0–5.0 with dilute acetic acid to protonate the surface amino groups and impart strong positive charge to the powder, thus obtaining an aminated tungsten powder suspension.

[0008] The mass-to-volume ratio of activated tungsten powder to anhydrous ethanol is 1 g:(8-20) mL.

[0009] Further, in step S1, the surface carboxylation process is as follows: Nanoscale spherical bismuth oxide powder is dispersed in anhydrous ethanol and ultrasonically treated in an ice-water bath until a uniform suspension is formed; polyacrylic acid is pre-dissolved in a small amount of deionized water or an ethanol-deionized water mixture, and added dropwise to the suspension under stirring. The mixture is stirred and reacted at 50–70°C for 2–4 hours, anchoring the polyacrylic acid to the particle surface through interfacial coordination, hydrogen bonding, and electrostatic interactions; after the reaction, the mixture is centrifuged at 6000–10000 rpm, the supernatant is discarded, and the precipitate is ultrasonically dispersed and centrifuged and washed with an ethanol-deionized water mixture at pH 6.0–7.0, repeated 2–4 times until the apparent pH of the supernatant stabilizes at 6.0–7.0, fully removing unanchored free polyacrylic acid; the washed precipitate is redispersed in anhydrous ethanol, and the apparent pH of the system is slowly adjusted to 6.0–7.0 with dilute ammonia, allowing the surface-anchored carboxyl groups to fully ionize into -COO. - The powder is then given a strong negative charge to obtain a carboxylated bismuth oxide suspension. The particle size of the nano-sized spherical bismuth oxide powder is 20–200 nm; the mass-to-volume ratio of the nano-sized spherical bismuth oxide powder to anhydrous ethanol is 1 g:(50–200) mL. The polyacrylic acid has a molecular weight of 1000 to 10000, and the amount of polyacrylic acid used is 1% to 10% of the mass of bismuth oxide powder; the volume ratio of ethanol to deionized water in the ethanol-deionized water mixture is (0.5 to 4):1.

[0010] Further, in step S1, the electrostatic self-assembly and amidation heat treatment process is as follows: under continuous mechanical stirring, the carboxylated bismuth oxide suspension is slowly dripped into the aminated tungsten powder suspension at a rate of 0.5–2.0 mL / min, keeping the tungsten powder completely suspended and without sediment at the bottom during the dripping process; after the dripping is completed, stirring is continued and intermittent ultrasonic treatment is performed for 0.5–2 h, so that the nano-spherical bismuth oxide particles are uniformly loaded onto the surface of the micron-sized spherical tungsten powder through electrostatic attraction; after the reaction is completed, the powder is filtered, broken up with anhydrous ethanol, and vacuum dried to obtain W@Bi2O3 precursor powder; The W@Bi2O3 precursor powder was uniformly spread in a corundum boat (thickness ≤ 3 mm) and placed under a continuously purged inert atmosphere. The temperature was programmed at a rate of 2–5 °C / min: first, the temperature was raised to 100–120 °C and held for 0.5–1 h to remove residual solvent and physically adsorbed water; then, the temperature was raised to 160–180 °C and held for 1–1.5 h to further remove bound water; finally, the temperature was raised to 220–250 °C and held for 2–3 h to allow the amino groups on the tungsten powder surface and the carboxyl groups anchored on the bismuth oxide surface to undergo an interfacial amidation reaction, forming covalent chemical bonds; after natural cooling to room temperature, the powder was gently sieved through a 200-mesh standard sieve to obtain a W@Bi2O3 core-satellite structure composite powder bonded by amide bonds. The parameters for the intermittent ultrasonic treatment are as follows: ultrasonic treatment for 20-60 seconds every 10-20 minutes of stirring, with an ultrasonic power of 100-200 W; the temperature for vacuum drying is 50-70℃, and the time is 3-6 hours; the inert atmosphere is high-purity argon or high-purity nitrogen, and the purging flow rate is based on continuously removing the water vapor generated by the reaction.

[0011] Furthermore, in step S1, Bi2O3 accounts for 10% to 30% of the total mass of the W@Bi2O3 core-satellite structure composite powder.

[0012] Furthermore, in step S2, the amount of W@Bi2O3 core-satellite structure composite powder in the X / γ ray shielding compound is 30% to 60% of the total mass of the X / γ ray shielding compound.

[0013] Further, in step S3, the surface pretreatment process is as follows: flake-shaped hexagonal boron nitride powder is added to ethanol or an ethanol-water solution containing a silane coupling agent, stirred and dispersed at room temperature to 60°C for 30–90 min, and then dried at 80–110°C to constant weight to obtain surface-pretreated flake-shaped hexagonal boron nitride powder; wherein, the amount of the silane coupling agent is 1%–5% of the mass of the hexagonal boron nitride powder; the average flake diameter of the flake-shaped hexagonal boron nitride is 1–10 μm, and the thickness is 20–100 nm; in the neutron shielding compound, the filling amount of the flake-shaped hexagonal boron nitride powder is 10%–30% of the total mass of the neutron shielding compound.

[0014] Further, in steps S2 and S3, the vulcanizing compounding agent comprises a vulcanizing agent, an activator, and an accelerator; the vulcanizing agent is sulfur, the activator includes zinc oxide and stearic acid, and the accelerator is selected from one or more of sulfenamides (CZ, NS, NOBS) and thiazoles (M, DM); based on 100 parts by weight of natural rubber matrix, the amount of stearic acid is 1-3 parts by weight, the amount of zinc oxide is 3-6 parts by weight, the amount of sulfur is 1.0-2.5 parts by weight, and the amount of accelerator is 0.5-1.5 parts by weight; the antioxidant is selected from one or more of amines (4010NA, 4020, RD) and hindered phenols, and the amount is 0.5-2.0 parts by weight.

[0015] Furthermore, in step S4, the temperature of the co-vulcanization integral hot pressing is 130-160°C, the pressure is 8-15 MPa, and the time is 5-8 min.

[0016] Secondly, this application provides a rubber-based functional composite material reinforced with inorganic fillers for a nuclear-satellite structure, prepared by the method described in the first aspect. The rubber-based functional composite material is a lead-free, flexible, thin-layer structure that possesses both X / γ-ray and neutron shielding properties, and exhibits bidirectional equivalent shielding capability. The bidirectional equivalent shielding capability refers to the relative deviation of the shielding efficiency measured on both sides of the material being ≤5% when X / γ-rays and thermal neutrons are incident perpendicularly from both sides of the shielding material, under test conditions of the same ray energy and sample thickness. The tensile strength of the rubber-based functional composite material is 14 MPa to 18 MPa, and the elongation at break is 700% to 860%.

[0017] Furthermore, the total thickness of the rubber-based functional composite material reinforced with inorganic filler in the nuclear-satellite structure is 0.8 mm to 1 mm; wherein, the thickness ratio of the upper neutron shielding layer, the middle X / γ ray shielding layer, and the lower neutron shielding layer is (0.5 to 2):1:(0.5 to 2).

[0018] In the technical solution of this application, a three-layer symmetrical configuration of "neutron shielding layer - X / γ-ray shielding layer - neutron shielding layer" is adopted, with plate-like hexagonal boron nitride enriched on both outer layers, which works in conjunction with hydrogen elements in the natural rubber matrix to achieve neutron attenuation: the hydrogen elements in the matrix are responsible for slowing down the incident fast neutrons, and the slowed thermal neutrons are attenuated by the hydrogen elements in the plate-like hexagonal boron nitride. 10B. High-efficiency absorption: W@Bi2O3 core-satellite structured composite powder is enriched in the intermediate core layer for dedicated X / γ-ray attenuation, achieving spatially ordered deployment and independent control of two shielding functions. This avoids the sedimentation and segregation defects caused by density differences among multiple fillers in traditional blending systems and endows the material with bidirectional equivalent shielding capability. Among them, the W@Bi2O3 core-satellite filler anchors nano-spherical bismuth oxide onto the surface of micron-sized spherical tungsten powder through amide covalent bonds. During mixing and sulfidation, it can maintain the composite state of two high-Z elements (W and Bi), eliminating micro-phase separation caused by density differences and ensuring high uniformity of shielding performance.

[0019] All three layers of this rubber-based functional composite material are made of natural rubber as the matrix. They are co-vulcanized and molded into a single unit, so that the rubber molecular chains at the interface are cross-linked and interpenetrated into a seamless whole, eliminating the interfacial stress and delamination risks common in heterogeneous laminated structures.

[0020] This nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material can be used in nuclear medicine interventional protective gloves, thyroid protective neck warmers, personal radiation protection clothing, shielding materials for nuclear medicine clinics; protective coverings for nuclear power plant pipelines and their auxiliary equipment; radiation hardening of spacecraft electronic devices; movable shielding curtains in nuclear emergency scenarios; and protective equipment for industrial radiation non-destructive testing.

[0021] This nuclear-satellite structure, reinforced with inorganic fillers, features a flexible, thin-layer structure with a total thickness controllable within the range of 0.8–1.0 mm. Its density is significantly lower than traditional lead-based products, and its elongation at break can reach over 700%, and under optimal conditions, over 800%. It also exhibits excellent bending compliance and processability. It can be used to manufacture protective gloves with high shielding effectiveness while maintaining finger dexterity, and thyroid neck braces that fit snugly, for use in interventional radiology procedures. Furthermore, it can be made into flexible shielding curtains for temporarily sealing radiation hotspots or field-fitting materials for wrapping irregularly shaped pipes, for use in nuclear power plant maintenance operations.

[0022] The inorganic filler-reinforced rubber-based functional composite material of this nuclear-satellite structure has bidirectional equivalent shielding capability, eliminating the need to distinguish between the front and back during installation and use, thus significantly improving work efficiency.

[0023] The beneficial effects of this application are as follows: This application provides a rubber-based functional composite material reinforced with inorganic fillers in a nuclear-satellite structure and its preparation method. Macroscopically, it adopts a functionally sequenced symmetrical configuration of "hexagonal boron nitride (h-BN) layer - W@Bi2O3 layer - hexagonal boron nitride (h-BN) layer," independently assigning neutron shielding to the outer two sides and X / γ-ray shielding to the middle core layer, respectively. This structurally avoids the weight segregation of fillers with different densities within the same system, eliminating the shielding efficiency loss caused by uneven filler distribution in traditional blending systems. This allows each functional filler to achieve a near-ideal uniform distribution and naturally possesses bidirectional equivalent shielding capability. Microscopically, through electrostatic self-assembly coupled amidation heat treatment, an amide covalent structure is constructed between the tungsten powder core and the bismuth oxide satellite particles. The bonding forms a stable W@Bi2O3 core-satellite structure, ensuring micro-regional consistency of shielding performance. The neutron shielding adhesive layer uses sheet-like hexagonal boron nitride, whose two-dimensional morphology tends to align in-plane under shear flow, forming a tortuous neutron transport path. This extends the neutron transport path within the layer, producing a "maze effect." This, combined with the fast neutron slowing function of hydrogen in the natural rubber matrix, forms a "slowing-absorption" synergistic attenuation chain, improving the overall neutron attenuation efficiency. In terms of molding process, all three layers use natural rubber as the matrix, achieving interlayer chemical bonding through a single co-vulcanization hot pressing, eliminating the risk of interfacial stress. The product is lead-free and environmentally friendly, balancing high shielding effectiveness, excellent mechanical properties, and wearing comfort. Moreover, the raw materials are readily available, the process is universal, and it is feasible for large-scale production.

[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0026] Figure 1 This is a macroscopic image of the W@Bi2O3 core-satellite structure composite powder prepared in Example 1; Figure 2 This is a scanning electron microscope (SEM) image of the W@Bi2O3 core-satellite structure composite powder prepared in Example 1; Figure 3 The image shows the EDS diagram of the W@Bi2O3 core-satellite structure composite powder prepared in Example 1. Figure 4The Fourier transform infrared spectra of the powders at each stage of the preparation process in Example 1 are shown below. Figure 5 This is a macroscopic photograph of the rubber-based functional composite material prepared in Example 1; Figure 6 Here is a surface SEM image of the rubber-based functional composite material prepared in Example 1; Figure 7 This is a cross-sectional view of the rubber-based functional composite material prepared in Example 1; Figure 8 The image shows a cross-sectional SEM image (low magnification) of the rubber-based functional composite material prepared in Example 1. Figure 9 The image shows a cross-sectional SEM image (high magnification) of the rubber-based functional composite material prepared in Example 1. Figure 10 This is an EDS diagram of the cross section of the rubber-based functional composite material prepared in Example 1. Detailed Implementation

[0027] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] To address the technical bottlenecks in current rubber-based inorganic filler composite materials, such as poor filler dispersion, weak interfacial bonding, and easy delamination in multilayer composites, as well as the special requirements for bidirectional shielding and lightweight flexibility in radiation shielding applications, this application proposes a rubber-based functional composite material reinforced with a nuclear-satellite structure inorganic filler. It adopts a functionally sequential symmetrical configuration of "neutron shielding layer - X / γ shielding layer - neutron shielding layer," enriching plate-like hexagonal boron nitride on both outer layers for thermal neutron absorption, and enriching W@Bi2O3 nuclear-satellite structure composite powder, bonded by amide bonds, in the middle core layer for X / γ ray attenuation. This eliminates the problems of filler sedimentation segregation and uneven distribution from the structural design source. Furthermore, all three layers are based on natural rubber and achieve interlayer chemical bonding through a single co-vulcanization hot pressing process, fundamentally overcoming the defect of weak interfacial bonding in heterogeneous laminated materials.

[0031] This application provides a method for preparing a rubber-based functional composite material reinforced with inorganic fillers for a nuclear-satellite structure, comprising the following steps: S1. Micron-sized spherical tungsten powder is subjected to surface oxidation activation treatment and amination treatment, and nano-sized spherical bismuth oxide powder is subjected to surface carboxylation treatment. Through electrostatic self-assembly and amidation heat treatment, W@Bi2O3 core-satellite structure composite powder with amide bond chemical bonding is obtained.

[0032] The process flow of surface oxidation activation and amination treatment is as follows: micron-sized spherical tungsten powder is added to hydrogen peroxide solution, stirred at room temperature and subjected to intermittent ultrasonic treatment for surface oxidation activation. After a uniform hydrated tungsten oxide thin layer is formed on the surface, it is washed with deionized water until neutral, and then replaced with anhydrous ethanol to obtain activated tungsten powder rich in hydroxyl grafting sites. Silane coupling agent KH550, deionized water, and anhydrous ethanol are mixed at a mass-volume ratio of 1g:(1~5)mL:(20~90)mL, and the pH is adjusted to 4~5 with acetic acid. The mixture is stirred at room temperature for 20~40 min until the solution is transparent to obtain KH550 pre-hydrolyzed solution.

[0033] The pre-hydrolysis step of the silane coupling agent KH550 is crucial to ensuring amination efficiency: KH550 is first fully hydrolyzed in an acetic acid-catalyzed alcohol-water system to convert its ethoxy groups into silanol groups. Then, it is added to a tungsten powder suspension. The silanol groups undergo a condensation reaction with the hydroxyl groups on the tungsten powder surface to form stable Si-OW bonds, anchoring the amino group to the tungsten powder surface. Adjusting the pH to 4.0–5.0 allows for sufficient protonation of the amino group, imparting a strong positive charge to the tungsten powder surface.

[0034] The micron-sized spherical tungsten powder has a particle size of 1–5 μm; the hydrogen peroxide solution has a mass fraction of 0.5%–1.0%, the mass-to-volume ratio of tungsten powder to hydrogen peroxide solution is 1 g:(2–5) mL, and the pre-hydroxylation treatment time is 0.5–1 h. The amount of silane coupling agent KH550 is 0.5%–2.0% of the mass of tungsten powder.

[0035] Subsequently, the activated tungsten powder was dispersed in anhydrous ethanol, and the KH550 pre-hydrolyzed solution was added. The mixture was stirred at 50–70 °C for 3–5 h. The reaction product was thoroughly washed with anhydrous ethanol to remove free silane, and then redispersed in anhydrous ethanol. The pH was adjusted to 4.0–5.0 with dilute acetic acid to obtain an aminated tungsten powder suspension.

[0036] The mass-to-volume ratio of activated tungsten powder to anhydrous ethanol is 1 g:(8-20) mL.

[0037] In the technical solution of this application embodiment, the purpose of surface oxidation activation treatment of tungsten powder is to generate an extremely thin layer of hydrated tungsten oxide on its surface, introducing abundant hydroxyl functional groups to provide sufficient active sites for the subsequent anchoring of silane coupling agents. Hydrogen peroxide can generate a hydroxyl-rich oxide film on the surface of tungsten powder. Controlling the concentration at 0.5% to 1.0% can avoid excessive oxidation leading to an excessively thick tungsten oxide layer, ensuring that the original spherical morphology of the powder is not damaged.

[0038] The surface carboxylation process is as follows: Nanoscale spherical bismuth oxide powder is dispersed in anhydrous ethanol and ultrasonically treated in an ice-water bath until a uniform suspension is formed. Polyacrylic acid is pre-dissolved in a small amount of deionized water or an ethanol-deionized water mixture, and added dropwise to the suspension with stirring. The mixture is stirred and reacted at 50–70°C for 2–4 hours. Polyacrylic acid is anchored to the particle surface through interfacial coordination, hydrogen bonding, and electrostatic interactions. After the reaction, the mixture is centrifuged at 6000–10000 rpm, and the supernatant is discarded. The precipitate is ultrasonically dispersed and centrifuged with an ethanol-deionized water mixture at pH 6.0–7.0, repeated 2–4 times until the apparent pH of the supernatant stabilizes at 6.0–7.0, thoroughly removing unanchored free polyacrylic acid. The washed precipitate is redispersed in anhydrous ethanol, and the apparent pH of the system is slowly adjusted to 6.0–7.0 with dilute ammonia to fully ionize the surface-anchored carboxyl groups into -COO. - The powder is then given a strong negative charge to obtain a carboxylated bismuth oxide suspension.

[0039] In the technical solution of this application embodiment, polyacrylic acid (PAA) is selected as the carboxylating agent. Its molecular chain contains a large number of carboxyl functional groups, which can be firmly anchored to the surface of bismuth oxide nanoparticles through interfacial coordination, hydrogen bonding, and electrostatic interactions, imparting a strong negative charge. PAA and Bi 3+The interfacial coordination enhances the thermal stability of polymer segments, ensuring sufficient reactive carboxyl groups are retained during subsequent high-temperature amidation, thus preventing rapid decarboxylation and decomposition. Pre-dissolving and dropwise addition avoids agglomeration caused by the poor solubility of PAA in anhydrous ethanol, guaranteeing uniform modification. Centrifugal washing instead of conventional filtration effectively prevents the formation of a dense filter cake on filter paper, encapsulating free PAA and ensuring complete removal of free polymer. Maintaining the washing solution pH at 6.0–7.0 ensures the carboxyl groups remain ionized, preventing the desorption of anchored PAA and maintaining the surface negative charge density. After redispersement, dilute ammonia is used to adjust the apparent pH of the suspension to 6.0–7.0, allowing the carboxyl groups to fully ionize into -COO. - With the -NH3 on the surface of tungsten amide powder + A strong electrostatic attraction is formed.

[0040] The nano-sized spherical bismuth oxide powder has a particle size of 20–200 nm; the polyacrylic acid has a molecular weight of 1,000–10,000, and the amount of polyacrylic acid used is 1%–10% of the mass of the bismuth oxide powder.

[0041] The volume ratio of ethanol to deionized water in the ethanol-deionized water mixture is (0.5–4):1.

[0042] The process flow for electrostatic self-assembly and amidation heat treatment is as follows: Under continuous mechanical stirring, the tungsten powder was kept completely suspended and free of sediment at the bottom during the dropwise addition process. The carboxylated bismuth oxide suspension was slowly added dropwise to the aminated tungsten powder suspension at a rate of 0.5–2.0 mL / min. After the addition was completed, stirring was continued and intermittent ultrasonic treatment was performed for 0.5–2 h to allow the nano-spherical bismuth oxide particles to be uniformly loaded onto the surface of the micron-sized spherical tungsten powder through electrostatic attraction. After the reaction was completed, the powder was filtered, slurried and broken up with anhydrous ethanol to break up the soft agglomerates, and then vacuum dried to obtain W@Bi2O3 precursor powder. The W@Bi2O3 precursor powder was uniformly spread in a corundum boat (thickness ≤ 3 mm) and placed under a continuously purged inert atmosphere. The temperature was programmed to rise at a rate of 2–5 °C / min: first, the temperature was raised to 100–120 °C and held for 0.5–1 h to remove residual solvent and physically adsorbed water; then, the temperature was raised to 160–180 °C and held for 1–1.5 h to further remove bound water; then, the temperature was raised to 220–250 °C and held for 2–3 h to allow the amino groups on the tungsten powder surface and the carboxyl groups anchored on the bismuth oxide surface to undergo an interfacial amidation reaction, forming covalent chemical bonds; after natural cooling to room temperature, the powder was gently sieved through a 200-mesh standard sieve to obtain W@Bi2O3 core-satellite structure composite powder bonded by amide bonds. The parameters for the intermittent ultrasonic treatment are as follows: ultrasonic treatment for 20-60 seconds every 10-20 minutes of stirring, with an ultrasonic power of 100-200 W; the temperature for vacuum drying is 50-70℃, and the time is 3-6 hours; the inert atmosphere is high-purity argon or high-purity nitrogen, and the purging flow rate is based on continuously removing the water vapor generated by the reaction.

[0043] In the technical solution of this application embodiment, the electrostatic self-assembly process utilizes the positively charged surface of amined tungsten powder and the negatively charged surface of carboxylated bismuth oxide to uniformly adsorb nano-bismuth oxide particles onto the surface of micron-sized tungsten powder through heterogeneous electrostatic attraction, forming a core-satellite precursor structure.

[0044] The slow dropwise addition and alternating stirring-ultrasound operation mode is conducive to the uniform distribution of nanoparticles on the surface of the core, avoiding localized rapid adsorption that leads to aggregation.

[0045] Amide heat treatment is the core step in imparting chemical stability to the core-satellite structure. The programmed temperature rise employs a gradient dehydration-reaction design. Holding at 100–120°C first thoroughly removes physically adsorbed water, preventing its vaporization at subsequent high temperatures that could lead to particle migration and aggregation. At 160–180°C, bound water is further removed, eliminating the inhibitory effect of moisture on the amidation dehydration equilibrium. Simultaneously, at this temperature, the amino and carboxyl groups undergo preliminary amidation, pre-anchoring the PAA chain segments to the two-phase interface, preventing PAA desorption and excessive decomposition during subsequent heating. Holding at 220–250°C allows the remaining active functional groups to undergo deep dehydration condensation, forming high-density amide covalent bonds, firmly anchoring bismuth oxide nanoparticles to the tungsten powder surface. This temperature window ensures the full progress of the amidation reaction while inhibiting excessive decomposition of the PAA backbone through interfacial coordination, thus fully preserving the core-satellite microstructure and nanoscale effect. The continuous purging of the inert atmosphere can promptly remove the water vapor generated during the reaction from the system, promoting a positive shift in the dehydration equilibrium and improving the amidation conversion rate.

[0046] The composite powder bonded by amidation is structurally stable and does not dissociate during subsequent mixing and vulcanization processes, thus eliminating the relative migration and segregation of high-density differential fillers at the source.

[0047] S2. The W@Bi2O3 core-satellite structure composite powder is mixed with a natural rubber matrix, and vulcanizing compounding agent and antioxidant are added to obtain X / γ ray shielding compound; In some embodiments, the amount of W@Bi2O3 core-satellite structure composite powder in the X / γ ray shielding compound is 30% to 60% of the total mass of the X / γ ray shielding compound.

[0048] S3. After surface pretreatment, the flake-shaped hexagonal boron nitride powder is mixed with natural rubber matrix, and vulcanizing compounding agent and antioxidant are added to obtain neutron shielding compound; The specific process for surface pretreatment is as follows: hexagonal boron nitride powder is added to ethanol or an ethanol-water solution containing a silane coupling agent, and stirred and dispersed at room temperature to 60°C for 30–90 min, followed by drying at 80–110°C to constant weight. The amount of silane coupling agent used is 1%–5% of the mass of the hexagonal boron nitride powder.

[0049] In neutron shielding compound, the amount of hexagonal boron nitride powder is 10% to 30% of the total mass of the neutron shielding compound.

[0050] In the technical solution of this application embodiment, plate-like hexagonal boron nitride (h-BN) is selected as the neutron absorber filler, and h-BN is enriched with... 10 B can efficiently capture thermal neutrons; its two-dimensional sheet-like morphology has a large specific surface area and a high aspect ratio, which can increase the contact probability between neutrons and the absorption cross section.

[0051] During the mixing process on an open mill, the lamellar filler tends to align in the in-plane direction under the action of the shear flow field, forming a tortuous neutron transport path within a limited layer thickness, producing a "maze effect" and further improving the neutron attenuation efficiency. The hydrogen element abundant in the natural rubber matrix has a good moderating function for fast neutrons, slowing down incident fast neutrons into thermal neutrons which are then efficiently absorbed by h-BN, forming a synergistic attenuation chain. Surface pretreatment can reduce the surface energy of h-BN, improve its interfacial compatibility and wettability with the natural rubber matrix, and increase the uniformity of filler dispersion.

[0052] In some embodiments, the average diameter of the sheet-like hexagonal boron nitride is 1–10 μm and the thickness is 20–100 nm.

[0053] In some embodiments, the surface modifier used for surface pretreatment is one of the silane coupling agents KH550, KH560, and KH570, and the amount used is 1% to 5% of the mass of the hexagonal boron nitride powder.

[0054] S4. Using the neutron shielding compound as the upper and lower layers and the X / γ ray shielding compound as the middle layer, the layers are stacked sequentially and then co-vulcanized and hot-pressed to obtain a rubber-based functional composite material reinforced with inorganic fillers of a nuclear-satellite structure.

[0055] In the technical solution of this application embodiment, sheet-like hexagonal boron nitride is enriched on both outer layers for thermal neutron absorption, and W@Bi2O3 core-satellite composite powder with amide bonds is used to fill the middle core layer to bear X / γ ray attenuation. The functional components are deployed sequentially between the layers without interfering with each other. The symmetrical configuration of the two outer layers gives the material bidirectional equivalent neutron shielding capability. All three layers are integrally molded with natural rubber as the matrix through co-vulcanization, so that the rubber molecular chains at the interface are cross-linked and interpenetrated into a seamless whole, eliminating the interface stress and delamination risks of heterogeneous stacked structures.

[0056] In the technical solution of this application embodiment, the use of W@Bi2O3 core-satellite filler in the intermediate core layer is a core design that distinguishes it from the prior art. The K-layer absorption edge of tungsten is approximately 69.5 keV, and the K-layer absorption edge of bismuth is approximately 90.5 keV, forming a synergistic complementary effect. Combined with the high-density uniform distribution of nano-bismuth oxide particles on the surface of micron-sized tungsten powder, a wide-spectrum continuous X / γ-ray shielding chain covering the energy range of 50–150 keV is formed. When the filler content is less than 30%, the volume concentration of high Z elements in the matrix is ​​insufficient, resulting in low photon attenuation efficiency; when the filler content is greater than 60%, the processing fluidity of the compound decreases, the flexibility and elongation at break of the material after vulcanization are significantly deteriorated, and the fillers are prone to form penetrating agglomerates, leading to stress concentration.

[0057] In some embodiments, in step S4, the thickness ratio of the upper neutron shielding layer, the middle X / γ ray shielding layer, and the lower neutron shielding layer is (0.5~2):1:(0.5~2), and the total thickness of the rubber-based functional composite material is 0.8 mm~1.0 mm.

[0058] In the technical solution of this application embodiment, the thickness ratio of the three layers can be flexibly adjusted according to the target application scenario. Consistent outer layer thickness on both sides ensures symmetrical bidirectional neutron shielding. When neutron shielding is the primary requirement, a larger outer layer / middle layer thickness ratio can be selected; when X / γ shielding is the primary requirement, the middle layer thickness ratio can be appropriately increased. When the total thickness is less than 0.8 mm, the filler has insufficient space to support it, making it difficult to achieve the areal density required for effective shielding; when the total thickness is greater than 1.0 mm, the overall weight and rigidity of the material increase, flexibility is lost, and uneven heating of the inner and outer layers during vulcanization may lead to inconsistent cross-linking degrees.

[0059] In some embodiments, in step S4, the temperature of the co-vulcanization integral hot pressing is 130–160°C, the pressure is 8–15 MPa, and the time is 5–8 min.

[0060] In the technical solution of this application embodiment, co-vulcanization hot pressing is the key process that distinguishes this application from the existing layered bonding process. The three layers of compounded rubber are stacked in a mold and vulcanized in one step. The unvulcanized rubber molecular chains at the interface diffuse, penetrate, and cross-link under heat and pressure, forming a seamless chemical bond interface without the need for an external adhesive layer. The three layers are made of the same matrix material, have consistent vulcanization characteristics, and exhibit minimal residual stress at the interface. The selection of vulcanization temperature, pressure, and time must balance sufficient vulcanization with production efficiency: too low a temperature results in slow vulcanization and low production efficiency; too high a temperature may lead to degradation of the rubber molecular chains or damage to the surface modification layer of the functional filler.

[0061] The nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material prepared by the aforementioned method is a flexible thin-layer structure with a total thickness of 0.8–1.0 mm. Its elongation at break can reach over 700%, and under optimal conditions, over 800%. It combines high shielding effectiveness, excellent mechanical properties, and wearing comfort. The material is lead-free and free of lead compounds, making it environmentally friendly.

[0062] This nuclear-satellite structure, reinforced with inorganic fillers, is a rubber-based functional composite material with bidirectional equivalent shielding capability, eliminating the need to distinguish between the front and back sides during installation. Neutrons, regardless of their entry point, are first moderated by hydrogen in the outer matrix and then efficiently absorbed by plate-like hexagonal boron nitride. When X-rays / gamma rays penetrate, they are efficiently attenuated by the intermediate W@Bi2O3 nuclear-satellite composite powder through photoelectric effect and Compton scattering. The two shielding functional components are spatially independent and each performs its specific function, achieving full-spectrum radiation synergistic shielding while maintaining the material's overall lightweight and flexibility.

[0063] This nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material can be used to prepare medical radiation protection equipment, including nuclear medicine interventional protective gloves, thyroid protective neck warmers, personal radiation protection clothing, and shielding materials for nuclear medicine treatment rooms; it can also be used to prepare nuclear power plant pipeline protection materials, spacecraft electronic device radiation protection materials, nuclear emergency movable shielding curtains, or industrial X-ray non-destructive testing protection equipment.

[0064] This nuclear-satellite structure, reinforced with inorganic fillers, is a flexible and bendable rubber-based functional composite material suitable for manufacturing comfortable, close-fitting protective equipment. In nuclear medicine, it can be used for X-ray protective gloves and thyroid protective neck warmers for interventional radiologists, providing good finger dexterity and neck support while ensuring shielding effectiveness. In nuclear power plant maintenance, it can be made into movable shielding curtains and flexible wrapping materials for temporary radiation hotspot isolation and protection of irregularly shaped pipes, eliminating the need to distinguish between the front and back during installation and significantly improving work efficiency. In nuclear emergency response, its lightweight and foldable nature facilitates pre-storage and rapid deployment.

[0065] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0066] Example 1 This embodiment provides a method for preparing a rubber-based functional composite material reinforced with inorganic fillers in a nuclear-satellite structure, comprising the following steps: Preparation of S1.W@Bi2O3 core-satellite structure composite powder: 16.00 g of micron-sized spherical tungsten powder was weighed and added to 40 mL of 1.0% hydrogen peroxide solution (the mass-volume ratio of tungsten powder to hydrogen peroxide solution was 1 g: 2.5 mL). The mixture was magnetically stirred at room temperature and ultrasonicated at 150 W for 1 min every 10 min, for a total of 1 h, to complete the surface oxidation activation treatment, forming a uniform hydrated tungsten oxide thin layer on the powder surface. The product was filtered and washed with deionized water until neutral, and then replaced twice with anhydrous ethanol to obtain wetted activated tungsten powder.

[0067] Add 0.16 g KH550 (1.0% of the tungsten powder mass), 0.5 mL deionized water, and 10 mL anhydrous ethanol (the mass-volume ratio of KH550, deionized water, and anhydrous ethanol is 1 g: 3.13 mL: 62.5 mL) to a 50 mL dry beaker. Adjust the pH to 4-5 by adding glacial acetic acid dropwise, and stir at room temperature for 30 min to obtain a transparent pre-hydrolyzed solution.

[0068] Activated tungsten powder was transferred to a 1 L beaker, and 200 mL of anhydrous ethanol was added (the mass-to-volume ratio of tungsten powder to anhydrous ethanol was 1 g:12.5 mL). The mixture was ultrasonically dispersed at 200 W in an ice-water bath for 20 min. All the pre-hydrolyzed solution was added, the beaker was sealed, and the mixture was stirred at 300 rpm in a 60℃ water bath for 4 h. After cooling, the mixture was filtered and washed three times with anhydrous ethanol to thoroughly remove free silane. The filter cake was redispersed in 200 mL of anhydrous ethanol, and the pH was adjusted to 4.5 with 0.1 mol / L dilute acetic acid to fully protonate the surface amino groups and impart a strong positive charge to the powder, resulting in an aminated tungsten powder suspension. 4.00 g of nano-sized spherical Bi₂O₃ powder was taken and added to 400 mL of anhydrous ethanol (the mass-to-volume ratio of bismuth oxide to anhydrous ethanol was 1 g:100 mL). The mixture was ultrasonically dispersed at 250 W in an ice-water bath for 45 min (with a 5 min pause every 15 min). Add 0.16 g of a 50% (w / w) aqueous solution of polyacrylic acid (molecular weight approximately 5000, amounting to 2% of the mass of bismuth oxide) dropwise to the above suspension while stirring. React at 300 rpm for 3 hours in a 60°C water bath. After the reaction, aliquot into centrifuge tubes, centrifuge at 8000 rpm for 10 minutes, and discard the supernatant. Add approximately 40 mL of an ethanol-deionized water mixture (volume ratio 1:1, pH pre-adjusted to 6.5) to each tube, sonicate to resuspend for 5 minutes, and centrifuge again under the same conditions. Repeat the washing process three times until the apparent pH of the supernatant stabilizes at approximately 6.5, thoroughly removing unanchored free polyacrylic acid. Combine the precipitates and redisperse them in 400 mL of anhydrous ethanol. Sonicate in an ice-water bath for 10 minutes. Slowly adjust the apparent pH of the system to 6.5 with 0.1 mol / L dilute ammonia to fully ionize the surface carboxyl groups and impart a strong negative charge to the powder, obtaining a carboxylated bismuth oxide suspension.

[0069] In a 1 L tall beaker, the aminated tungsten powder suspension was stirred at approximately 350 rpm to ensure complete suspension and prevent sedimentation at the bottom. The carboxylated bismuth oxide suspension was added dropwise at a rate of approximately 1 mL / min. After the addition was complete, the reaction was repeated four times using a cycle of "stirring for 15 min - sonication in an ice-water bath for 30 s (150 W)". After the reaction was complete, the mixture was filtered under reduced pressure. The filter cake was broken up with approximately 50 mL of anhydrous ethanol and spread onto a petri dish (thickness ≤ 3 mm). The dish was then placed in a vacuum drying oven containing anhydrous calcium chloride and dried under vacuum at 60°C for 5 h. After drying, the vacuum pump was turned off, and high-purity argon gas was introduced to atmospheric pressure before the sample was removed.

[0070] The dried powder was evenly spread in a corundum boat (thickness ≤ 3 mm) and then transferred to a sealed tubular furnace. High-purity argon gas was first purged at a flow rate of 100 mL / min for 30 min to purge the air from the furnace. The flow rate was then reduced to 50 mL / min and maintained throughout the purging process to remove the water vapor generated during the reaction. The temperature program was set as follows: the temperature was increased to 100℃ at 5℃ / min and held for 1 h to remove residual solvent and physically adsorbed water; then increased to 170℃ at 3℃ / min and held for 1 h to further remove bound water; finally, the temperature was increased to 240℃ at 3℃ / min and held for 2 h to allow the amino groups on the tungsten powder surface and the carboxyl groups anchored on the bismuth oxide surface to undergo an interfacial amidation reaction, forming covalent chemical bonds. After natural cooling to room temperature with the furnace, the powder was gently sieved through a 200-mesh standard sieve to obtain the amide-bonded W@Bi2O3 core-satellite structure composite powder, as shown in the image below. Figure 1 As shown in the figure. Among them, Bi2O3 accounts for about 20% of the total mass of the composite powder (Bi2O3 loading).

[0071] Preparation of S2.X / γ-ray shielding compound: By weight: 100 parts natural rubber, 167 parts of the above-mentioned W@Bi2O3 core-satellite structure composite powder (powder filling amount is 60%), 5 parts zinc oxide, 2 parts stearic acid, 1.5 parts antioxidant 4010NA, 1.0 part accelerator CZ, and 1.8 parts sulfur. The compounding process is completed on an open mill according to conventional rubber processing procedures: after the raw rubber is plasticized and rolled, zinc oxide, stearic acid, antioxidant, and W@Bi2O3 composite powder are added sequentially. After mixing thoroughly, the accelerator and sulfur are added, and the mixture is passed through a thin sheet several times before being sheeted and cooled.

[0072] S3. Preparation of neutron-shielded compound: By weight: 100 parts natural rubber, 28 parts flake hexagonal boron nitride (20% filler of hexagonal boron nitride powder), 5 parts zinc oxide, 2 parts stearic acid, 1.5 parts antioxidant 4010NA, 1.2 parts accelerator CZ, and 2.0 parts sulfur. The mixing process is the same as in step S2, wherein the flake hexagonal boron nitride powder is pre-treated with silane coupling agent KH550 (the amount of coupling agent is 2% of the mass of h-BN).

[0073] S4. Co-vulcanization integral molding: Weigh out the compound rubber of each layer (total thickness approximately 1.0 mm) according to a thickness ratio of 0.5:1:0.5. Stack the compound rubber in the mold in the following order: neutron shielding compound rubber (upper layer), X / γ-ray shielding compound rubber (middle layer), and neutron shielding compound rubber (lower layer). Hot-press on a flat vulcanizing machine at 145℃ and 10 MPa for 8 min, then allow to cool naturally before demolding to obtain a rubber-based functional composite material reinforced with inorganic fillers in a nuclear-satellite structure. A picture of the actual product is shown below. Figure 5 As shown.

[0074] Depend on Figure 1It is evident that the W@Bi2O3 core-satellite structure composite powder is a uniform dark gray powder with no obvious large agglomerates. The powder has good flowability, which meets the raw material requirements of subsequent rubber compounding processes.

[0075] Figure 2 This is a scanning electron microscope (SEM) image of the W@Bi2O3 core-satellite composite powder. The image clearly shows the typical core-satellite microstructure: the micron-sized spherical tungsten powder core is spherical with a particle size of about 1~5μm; its surface is loaded with nano-sized spherical bismuth oxide particles with a particle size of about 20~50nm.

[0076] Figure 3 The image shows the EDS (Electronic Data Distribution) of W@Bi2O3 core-satellite structure composite powder, including the SEM (Series Electron Microscopy) image of the composite powder, the EDS layered image of the composite powder, the EDS surface distribution map of tungsten (W), and the EDS surface distribution map of bismuth (Bi).

[0077] Energy dispersive spectroscopy results show that tungsten is mainly concentrated in the micron-sized spherical core region, while bismuth is uniformly covered on the core surface. The two elements do not cross-aggregate, which directly confirms the successful construction of the core-satellite structure with tungsten as the core and bismuth oxide as the satellite.

[0078] Fourier transform infrared spectroscopy was used to characterize the surface functional groups of aminated modified tungsten powder, carboxylated nano-bismuth oxide, and heat-treated amidated W@Bi2O3 core-satellite structure composite powder. The results are as follows: Figure 4 As shown.

[0079] As can be seen, the aminated modified tungsten powder has a viscosity of 3200~3700 cm⁻¹ -1 The broadened absorption band in the region is mainly due to the OH stretching vibrations of adsorbed water and hydroxyl groups on the powder surface, superimposed with the NH stretching vibration signal of grafted amino groups; 1560 cm⁻¹ -1 The absorption peak at 1075 cm⁻¹ corresponds to the in-plane bending vibration of the NH group of the amino group. -1 The absorption peak at the point is attributed to the superposition of Si-OW and Si-O-Si silicon-oxygen bond vibrations, and the three together prove that the silane coupling agent KH550 has been successfully grafted onto the surface of tungsten powder.

[0080] Carboxylated bismuth nanoparticles at 1725 cm⁻¹ -1 The presence of a strong characteristic absorption peak of free carboxyl C=O stretching vibration indicates that polyacrylic acid was successfully loaded onto the bismuth oxide surface, endowing it with abundant surface carboxyl functional groups.

[0081] After amidation heat treatment at 240℃, the resulting composite powder was 1725 cm⁻¹ -1 The characteristic absorption peak of the carboxyl group at 1650 cm⁻¹ completely disappeared, while the characteristic absorption peak of the carboxyl group at 1650 cm⁻¹ disappeared completely. -1 and 1540 cm-1 Typical absorption peaks of amide I (C=O stretching vibration) and amide II (coupling of NH bending vibration and CN stretching vibration) appear at 1075 cm⁻¹, respectively; and at 1075 cm⁻¹ -1 The stable presence of the Si-OW bond characteristic peak indicates that the amidation reaction did not disrupt the bonding structure between the silane coupling agent and the tungsten powder. These results directly demonstrate that the amino groups on the tungsten powder surface and the carboxyl groups on the bismuth oxide surface underwent an amidation reaction, forming stable amide covalent bonds, ultimately achieving the chemical bonding connection of the W@Bi2O3 core-satellite structure.

[0082] Figure 5 This is a macroscopic image of the rubber-based functional composite material with a nuclear-satellite structure reinforced by inorganic fillers, prepared in Example 1. The material appears as a white, flexible sheet with a smooth, flat surface, free from molding defects such as bubbles, cracks, or missing adhesive.

[0083] Figure 6 The image shows a surface SEM image of the prepared rubber-based functional composite material. The image reveals that the natural rubber matrix forms a continuous and uniform phase structure, without obvious large-sized aggregates or significant interfacial gaps.

[0084] Figure 7 The image shows a cross-sectional view of the prepared rubber-based functional composite material. The image clearly shows a three-layer symmetrical structure consisting of a neutron shielding layer, an X / γ-ray shielding layer, and a neutron shielding layer. Each layer has a uniform thickness, and the interlayer bonding is tight and seamless, with no delamination.

[0085] Figure 8 , 9 The image shows a cross-sectional SEM image of the prepared rubber-based functional composite material. The microscopic differences of the three-layer structure are clearly distinguishable in the image: in the upper and lower layers, lamellar hexagonal boron nitride fillers are oriented in the in-plane direction within the rubber matrix; in the middle layer, W@Bi2O3 core-satellite structured composite powder is uniformly dispersed within the rubber matrix; there are no obvious interfacial boundaries between the layers, indicating that the co-vulcanization integral molding process causes cross-linking and interpenetration of the rubber molecular chains at the interfaces, forming a seamless overall structure.

[0086] Figure 10 The image shows the cross-sectional EDS diagram of the rubber-based functional composite material prepared in Example 1, including the SEM image of the rubber-based functional composite material, the EDS surface distribution diagram of boron (B), the EDS surface distribution diagram of bismuth (Bi), and the EDS surface distribution diagram of tungsten (W).

[0087] Energy dispersive spectroscopy results show that boron is mainly concentrated in the outer regions on the top and bottom sides, while tungsten and bismuth are mainly concentrated in the middle core region. The elemental distribution is completely consistent with the layered structure design of functional zoning, and there is no obvious cross-layer diffusion phenomenon, which verifies the technical effect of functional zoning deployment.

[0088] Test method: (1) X / γ-ray-thermal neutron radiation shielding performance test: The prepared rubber-based functional composite material was cut into samples with a length and width of 10cm × 10cm and a thickness of 1mm. Following the narrow-beam transmission method in YY / T 0292.1-2020 "Medical Diagnostic X-ray Radiation Protection Apparatus Part 1: Determination of Material Attenuation Properties", samples were tested for 65 keV X-rays, 120 keV X-rays, and 662 keV X-rays, respectively. 137 The incident and transmitted dose rates of Cs-γ rays were measured to calculate the shielding efficiency. The shielding efficiency calculation formula is: η=(1-I / I0)×100%, where I0 is the incident dose rate without a sample and I is the transmitted dose rate with a sample. Following the gold foil activation method in ASTM E262-17 "Standard Method for Measuring Thermal Neutron Reactivity by Radioactive Counting Techniques", the incident and transmitted activation count rates of 0.025 eV thermal neutrons were tested to calculate the neutron shielding efficiency. The neutron shielding efficiency calculation formula is: η=(1-A / A0)×100%, where A0 is the activation count rate of the gold foil without a sample and A is the activation count rate of the gold foil with a sample.

[0089] Bidirectional equivalent shielding performance test: The sample is flipped along the thickness direction, with the reverse side as the incident surface of the radiation. The positions of the radiation source and detector, as well as all test parameters, are kept completely consistent with the front incident test. The above test is repeated, and the shielding efficiency is calculated. The relative deviation of the bidirectional shielding efficiency is calculated using the following formula: ; (2) Tensile property test: According to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", the specimen was cut into a standard dumbbell shape of type 1. The tensile strength and elongation at break were tested using a universal electronic tensile testing machine at a tensile speed of 500 mm / min. The effective number of repeated tests was ≥5 times, and the arithmetic mean of all effective data was taken as the final result.

[0090] (3) Fourier transform infrared spectroscopy (FT-IR) test: Samples were prepared using the potassium bromide pellet method, and the wavenumber range was 4000 cm⁻¹. -1 ~400 cm -1 Spectral resolution of 4 cm -1 The number of scans was 32, and the test was conducted at room temperature.

[0091] Examples 2-3 and Comparative Examples 1-3 Compared with Example 1, the only difference is that in step S1, the percentage of Bi2O3 in the total mass of the composite powder is different, that is, the loading of Bi2O3 is different. The rest is roughly the same as Example 1, and will not be repeated here.

[0092] The performance of the nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite materials prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the results are shown in Table 1.

[0093] Table 1 It should be noted that in the table, the 65 keV X-ray shielding efficiency is abbreviated as "65 keV shielding efficiency", the 120 keV X-ray shielding efficiency is abbreviated as "120 keV shielding efficiency", and the 662 keV γ-ray shielding efficiency is abbreviated as "662 keV shielding efficiency", and the same applies to subsequent tables.

[0094] As shown in Table 1, with the increase of Bi2O3 loading, the shielding efficiency of 65 keV X-rays shows a monotonically decreasing trend, the shielding efficiency of 120 keV X-rays shows a monotonically increasing trend with the growth rate gradually slowing down, the shielding efficiency of 662 keV γ-rays shows a slow decreasing trend with minimal overall fluctuation, and the neutron shielding rate is maintained between 56% and 58% overall; the tensile strength shows a trend of first increasing and then decreasing, reaching a peak at 20% loading, while the elongation at break continues to decrease.

[0095] The energy dependence of the shielding efficiency mentioned above stems from the complementary absorption edges of the K-layers of tungsten and bismuth. Tungsten's K-layer absorption edge is approximately 69.5 keV, and it approaches the absorption edge in the 65 keV energy range, exhibiting a higher photoelectric effect cross-section and significantly better attenuation per unit mass compared to Bi₂O₃. Therefore, increasing the proportion of Bi₂O₃ leads to a gradual decrease in shielding efficiency at 65 keV. Bismuth's K-layer absorption edge is approximately 90.5 keV, and it has already surpassed the absorption edge in the 120 keV energy range. Its attenuation per unit mass coefficient is higher than that of tungsten. Therefore, increasing the proportion of Bi₂O₃ can improve the shielding efficiency at 120 keV, and the shielding gain gradually narrows with increasing Bi₂O₃ proportion. In the 662 keV energy range, Compton scattering is dominant. Tungsten and bismuth have similar electron densities per unit mass, resulting in minimal difference in intrinsic attenuation capabilities. Furthermore, Bi₂O₃, due to its oxygen content, has a slightly lower attenuation per unit mass coefficient than pure tungsten. Therefore, the shielding efficiency decreases slowly with increasing Bi₂O₃ proportion, without significant change. Specifically, at a 20% loading, the material's efficiency is highest between 50 and 150 keV. The shielding performance is most balanced across the commonly used medical spectral range of keV, and the overall shielding performance is optimal across a wide spectrum.

[0096] In terms of mechanical properties, when the Bi2O3 loading increases from 5% to 20%, the core-satellite structure nanosatellite particles can play a nano-reinforcing role, the filler is uniformly dispersed and the interface is well bonded, and the tensile strength gradually increases. When the loading exceeds 20%, the excess nano-bismuth oxide is prone to agglomeration and stress concentration, and the relative proportion of tungsten cores decreases, which weakens the load-bearing role of micron particles, resulting in a drop in tensile strength. The elongation at break continues to decrease with the increase of the total amount of rigid filler.

[0097] The neutron shielding efficiency is mainly determined by the boron content of the plate-like hexagonal boron nitride on both outer layers. The change in the Bi2O3 loading in the middle layer has no significant effect on it. Considering the balance between wide energy spectrum shielding and mechanical properties, the Bi2O3 loading is preferably 10% to 30%.

[0098] Examples 4-5 and Comparative Examples 4-6 Compared with Example 1, the only difference is that the filling amount of W@Bi2O3 core-satellite structure composite powder is different in step S2. The rest is roughly the same as Example 1, and will not be repeated here.

[0099] The performance of the nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite materials prepared in Examples 4-5 and Comparative Examples 4-6 was tested, and the results are shown in Table 2.

[0100] Table 2 As shown in Table 2, with the increase of the W@Bi2O3 nuclear-satellite composite powder filling amount, the X / γ-ray shielding efficiency shows a monotonically increasing trend, which conforms to the marginal decrease law of radiation index decay; the neutron shielding efficiency is basically stable at around 57%, and is less affected by the change of the intermediate layer filling amount; the tensile strength shows a trend of first increasing and then decreasing, reaching a peak at 60% filling amount, while the elongation at break continues to decrease. Within the filling amount range of 30% to 60%, the material has both good shielding effectiveness and excellent flexibility and processability; after the filling amount exceeds 60%, although the shielding efficiency still improves slightly, the processing fluidity of the compound decreases significantly, and the filler is prone to micro-area agglomeration, causing stress concentration. After vulcanization, the elongation at break and flexibility of the material deteriorate severely, which cannot meet the requirements of flexible wearable and bending adaptation. Therefore, the preferred filling amount of the composite powder is 30% to 60%.

[0101] Examples 6-7 and Comparative Examples 7-8 Compared with Example 1, the only difference is that the amount of lamellar hexagonal boron nitride powder filled in step S3 is different. The rest is roughly the same as Example 1, and will not be repeated here.

[0102] The performance of the rubber-based functional composite materials with inorganic fillers for nuclear-satellite structure prepared in Examples 6-7 and Comparative Examples 7-8 was tested, and the results are shown in Table 3.

[0103] Table 3 As shown in the table above, with the increase of h-BN filling amount, the neutron shielding efficiency continues to rise, the X / γ ray shielding efficiency is basically stable, the tensile strength shows a trend of first rising and then falling, and the elongation at break continues to decrease.

[0104] The reason lies in: h-BN 10 Boron (B) is the core element for thermal neutron absorption, and an increase in its content directly increases the neutron capture probability. h-BN is concentrated in the outer layers on both sides and does not participate in the attenuation of X / γ rays in the middle layer. Therefore, the X / γ ray shielding efficiency fluctuates only within a small range and the change is not significant.

[0105] Within the filler content range of 5% to 20%, tensile strength increases with increasing h-BN filler content. This is because the flake filler has a large specific surface area and a wide contact interface with the rubber matrix; appropriate addition can play a reinforcing role, and uniformly dispersed h-BN flakes can effectively transfer and bear stress. When the filler content exceeds 20%, the excess flake filler is difficult to completely disperse during mixing, and some h-BN flakes stack to form agglomerates, leading to stress concentration and a decrease in tensile strength. The continuous decrease in elongation at break is due to the increased rigid flake filler restricting the slippage and extension of rubber molecular chains. Overall, a filler content of 10% to 30% for flake hexagonal boron nitride powder is more suitable.

[0106] Examples 8-9 and Comparative Examples 9-10 Compared with Example 1, the only difference is that in step S4, the thickness ratio of the upper, middle and lower shielding functional adhesive layers is different. The rest is roughly the same as Example 1, and will not be repeated here.

[0107] The performance of the nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite materials prepared in Examples 8-9 and Comparative Examples 9-10 was tested, and the results are shown in Table 4.

[0108] Table 4 As shown in the table, as the thickness ratio of the upper and lower shielding layers increases (i.e., the outer layer thickens and the middle layer thins), the neutron shielding efficiency continues to rise, the X / γ ray shielding efficiency continues to decline, the tensile strength shows a trend of first rising and then falling, while the elongation at break continues to rise.

[0109] The reasons are as follows: the thickening of the outer layer increases the absorption path of thermal neutrons by the plate-like hexagonal boron nitride, thus enhancing the neutron attenuation capability; the thinning of the middle layer weakens the photoelectric absorption and Compton scattering effect of W@Bi2O3 nuclei on X / γ rays, thereby reducing the shielding efficiency; a moderate thickness of the middle layer can fully utilize the load-bearing and reinforcing effect of W@Bi2O3 filler. If the middle layer is too thin, the volume of the reinforcement is insufficient; if it is too thick, the overall rigidity of the material increases and the internal strain coordination deteriorates, both of which lead to a decrease in tensile strength; the outer h-BN / NR layer has better flexibility than the middle layer, and its increased proportion gradually increases the overall elongation at break of the material.

[0110] Example 10 The radiation aging resistance of the nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material prepared in Example 1 was tested. 60 A Co-γ ray source was used for irradiation in air at room temperature, with a dose rate of 1×10⁻⁶. 5 rad / h, cumulative dose 1×10 6 Rad; After irradiation, the sample was placed at 23 °C and 50% relative humidity for 24 h before performance testing.

[0111] Example 11 The nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material prepared in Example 1 was flipped along the thickness direction, with the reverse side as the ray incident surface. All test parameters were kept completely consistent with those in Example 1 before the shielding performance test was performed.

[0112] Comparative Example 11 The same amount of tungsten powder, Bi2O3, and h-BN as in Example 1 were directly blended into natural rubber, and then vulcanized in a single layer with a total thickness of 1 mm. The total filler areal density was the same as in Example 1, thus obtaining a rubber-based functional composite material.

[0113] Comparative Example 12 Compared with Example 1, the only difference is that in step S1, only electrostatic self-assembly is performed to obtain the W@Bi2O3 precursor, and the 240℃ amidation heat treatment is not performed. The rest is roughly the same as Example 1, and will not be repeated here.

[0114] Comparative Example 13 Compared with Example 1, the only difference is that the intermediate layer compound is replaced with pure tungsten powder of the same mass as the W@Bi2O3 composite powder in Example 1 (without Bi2O3). The rest is roughly the same as Example 1, and will not be repeated here.

[0115] Comparative Example 14 Compared with Example 1, the only difference is that the intermediate layer compound is replaced with pure Bi2O3 powder of the same mass as the W@Bi2O3 composite powder in Example 1 (without tungsten powder). The rest is roughly the same as Example 1, and will not be repeated here.

[0116] Comparative Example 15 The same amount of W@Bi2O3 and h-BN as in Example 1 were directly blended into natural rubber, and vulcanized in a single layer with a total thickness of 1 mm. The total filler areal density was the same as in Example 1, thus obtaining a rubber-based functional composite material.

[0117] Comparative Example 16 Compared with Example 1, the only difference is that in step S4, two neutron shielding functional adhesive layers and one X / γ ray shielding functional adhesive layer are vulcanized separately. Then, bisphenol A type epoxy resin E-51 (with polyamide 650 curing agent, the mass ratio of the two is 1:1) is used as an adhesive. The neutron shielding functional adhesive layer, the X / γ ray shielding functional adhesive layer and the neutron shielding functional adhesive layer are stacked and bonded in sequence at a thickness ratio of 0.5:1:0.5. The mixture is then cured at 80°C and 0.5 MPa for 2 hours to ensure that the total thickness of the final composite sample is consistent with that of Example 1, which is 1 mm. Other aspects are roughly the same as in Example 1 and will not be repeated here.

[0118] The performance of the nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite materials prepared in Examples 10-11 and Comparative Examples 11-16 was tested, and the results are shown in Table 5.

[0119] Table 5 Note: Mechanical properties are independent of the incident direction of the radiation. In Example 11, the mechanical properties were not tested again, and the same mechanical property data as in Example 1 were used.

[0120] As can be seen from the data in Table 5, in Example 10, the rubber-based functional composite material was subjected to 1×10 6 After irradiation with a cumulative dose of gamma rays, the performance of the material decreased only slightly compared to Example 1, indicating that the material has excellent resistance to radiation aging.

[0121] The reverse test results of Example 11 show that, compared with Example 1, the relative deviation of the bidirectional shielding efficiency of each energy segment is less than 2%, which meets the bidirectional equivalent judgment standard of ≤5%, verifying that the material has excellent bidirectional equivalent shielding capability.

[0122] In Comparative Example 11, all fillers were directly blended into a single layer of natural rubber and vulcanized. Due to the significant density differences among tungsten powder, bismuth oxide, and hexagonal boron nitride, under conventional mixing processes, high-density tungsten powder and bismuth oxide settled to the bottom of the sample, while low-density flake-like boron nitride floated to the upper layer. Furthermore, nano-bismuth oxide was prone to local agglomeration. Ultimately, the fillers exhibited severe spatial unevenness in both the thickness direction and the plane, forming numerous weak shielding areas with low filler concentrations. Based on the convexity of radiation exponential decay, the overall macroscopic shielding efficiency of the non-uniformly distributed system was significantly lower than that of the ideal uniformly distributed system. Therefore, the X / γ-ray and neutron shielding efficiencies were significantly lower than in Example 1. Simultaneously, filler segregation and agglomeration caused significant stress concentration, leading to a significant deterioration in tensile strength and elongation at break. These results fully demonstrate that the synergistic design of the functionally ordered three-layer structure and the core-satellite filler can effectively eliminate the performance loss caused by filler segregation, achieving superior shielding and mechanical properties with the same total filler content.

[0123] In Comparative Example 12, the amidation heat treatment step was omitted, and W and Bi2O3 were only bonded by electrostatic adsorption. Under the action of mixing shear force, the core-satellite structure was partially dissociated, and the X / γ shielding efficiency and tensile strength were significantly reduced compared with Example 1, indicating that the chemical bonding of amide bonds plays a key role in maintaining the integrity of the core-satellite structure.

[0124] In Comparative Example 13, the intermediate layer was filled with only the same mass of pure tungsten powder. The shielding efficiency in the 65 keV low-energy band was slightly higher than that in Example 1. However, in the 120 keV mid-energy band, the attenuation capability was significantly reduced due to the lack of bismuth element K-side supplementation, indicating a shortcoming in mid-energy band shielding.

[0125] In Comparative Example 14, the intermediate layer was filled with only the same mass of pure Bi₂O₃ powder. The shielding efficiency in the mid-energy band of 120 keV was slightly higher than that in Example 1, but the attenuation capability in the low-energy band of 65 keV was insufficient, indicating a weakness in low-energy band shielding. Both sets of results jointly confirm that the absorption edges of W and Bi in the K layer are synergistically complementary, achieving balanced shielding over a wide energy spectrum range of 50–150 keV, avoiding the specific energy band performance defects of a single high-Z element.

[0126] In Comparative Example 15, W@Bi2O3 and h-BN were blended in a single layer. The significant difference in their densities led to sedimentation segregation and uneven spatial distribution of the filler, resulting in a large number of weak shielding areas. As a result, the neutron shielding efficiency and X / γ shielding efficiency both decreased significantly, verifying the necessity of the functionally ordered three-layer structure for eliminating segregation and improving the actual shielding performance.

[0127] In Comparative Example 16, the process of bonding epoxy resins after separate vulcanization was adopted. Due to defects in the bonding interface and the lack of cross-linking and interpenetration of rubber molecular chains, the tensile strength and elongation at break were significantly reduced compared to Example 1, which was co-vulcanized and integrally molded. This indicates that the co-vulcanization process makes a decisive contribution to the interlayer bonding strength.

[0128] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a rubber-based functional composite material reinforced with inorganic fillers in a nuclear-satellite structure, characterized in that, Includes the following steps: S1. Micron-sized spherical tungsten powder is subjected to surface oxidation activation treatment and amination treatment, and nano-sized spherical bismuth oxide powder is subjected to surface carboxylation treatment. Through electrostatic self-assembly and amidation heat treatment, W@Bi2O3 core-satellite structure composite powder with amide bond chemical bonding is obtained. S2. The W@Bi2O3 core-satellite structure composite powder is mixed with a natural rubber matrix, and vulcanizing compounding agent and antioxidant are added to obtain X / γ ray shielding compound; S3. After surface pretreatment, the flake-shaped hexagonal boron nitride powder is mixed with natural rubber matrix, and vulcanizing compounding agent and antioxidant are added to obtain neutron shielding compound; S4. Using the neutron shielding compound as the upper and lower layers and the X / γ ray shielding compound as the middle layer, the layers are stacked sequentially and then co-vulcanized and hot-pressed to obtain a rubber-based functional composite material reinforced with inorganic fillers of a nuclear-satellite structure.

2. The method for preparing the rubber-based functional composite material reinforced with inorganic fillers for a nuclear-satellite structure according to claim 1, characterized in that, In step S1, the process flow of surface oxidation activation treatment and amination treatment is as follows: micron-sized spherical tungsten powder is added to a hydrogen peroxide aqueous solution with a mass fraction of 0.5% to 1.0%, stirred at room temperature and subjected to intermittent ultrasonic treatment. After a uniform hydrated tungsten oxide thin layer is formed on the surface, it is washed with deionized water until neutral and replaced with anhydrous ethanol to obtain surface pre-hydroxylated activated tungsten powder; silane coupling agent KH550, deionized water, and anhydrous ethanol are mixed, and the pH is adjusted to 4 to 5 with acetic acid. The mixture is stirred at room temperature for 20 to 40 minutes until the solution is transparent to obtain KH550 pre-hydrolyzed solution. Subsequently, the activated tungsten powder was dispersed in anhydrous ethanol, and the KH550 pre-hydrolyzed solution was added. The mixture was stirred at 50–70 °C for 3–5 h. The reaction product was washed with anhydrous ethanol and then redispersed in anhydrous ethanol. The pH was adjusted to 4.0–5.0 with dilute acetic acid to obtain an aminated tungsten powder suspension.

3. The method for preparing the nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material according to claim 2, characterized in that, In step S1, the surface carboxylation process is as follows: nano-sized spherical bismuth oxide powder is ultrasonically dispersed in anhydrous ethanol; polyacrylic acid is added, and the mixture is stirred at 50-70°C for 2-4 hours; after the reaction, the mixture is centrifuged at 6000-10000 rpm, the supernatant is discarded, and the precipitate is ultrasonically dispersed and centrifuged and washed with an ethanol-deionized water mixture with a pH of 6.0-7.

0. This process is repeated 2-4 times until the apparent pH of the supernatant is stable at 6.0-7.0, thus removing free polyacrylic acid; the washed precipitate is redispersed in anhydrous ethanol, and the pH is adjusted to 6.0-7.0 with dilute ammonia to obtain a carboxylated bismuth oxide suspension.

4. The method for preparing the nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material according to claim 3, characterized in that, In step S1, the electrostatic self-assembly and amidation heat treatment process is as follows: Under stirring conditions, the carboxylated bismuth oxide suspension is added dropwise to the aminated tungsten powder suspension at a rate of 0.5–2.0 mL / min. After the addition is complete, stirring is continued and intermittent ultrasonic treatment is applied for 0.5–2 h, so that the nano-spherical bismuth oxide particles are uniformly loaded onto the surface of the micron-sized spherical tungsten powder through electrostatic attraction. After the reaction is completed, the powder is filtered, slurried with anhydrous ethanol, and vacuum dried to obtain W@Bi2O3 precursor powder. Subsequently, the W@Bi2O3 precursor powder is placed under an inert atmosphere and heated at a programmed heating rate of 2–5 °C / min: first, the temperature is raised to 100–120 °C and held for 0.5–1 h to remove residual solvent and adsorbed water, then the temperature is raised to 160–180 °C and held for 1–1.5 h to deeply remove bound water; the temperature is then raised to 220–250 °C and held for 2–3 h. h, the amino groups on the surface of tungsten powder and the carboxyl groups on the surface of bismuth oxide undergo an amidation reaction to form chemical bonds. After natural cooling, the mixture is sieved to obtain W@Bi2O3 core-satellite structure composite powder bonded by amide bonds. The process parameters of the intermittent ultrasonic treatment are: ultrasonic treatment for 20-60 seconds every 10-20 min of stirring, with an ultrasonic power of 100-200 W. The temperature of the vacuum drying is 50-70℃, and the time is 3-6 h. The inert atmosphere is high-purity argon or high-purity nitrogen.

5. The method for preparing the rubber-based functional composite material reinforced with inorganic fillers for a nuclear-satellite structure according to claim 1, characterized in that, In step S1, Bi2O3 accounts for 10% to 30% of the total mass of the W@Bi2O3 core-satellite structure composite powder.

6. The method for preparing the rubber-based functional composite material reinforced with inorganic fillers for a nuclear-satellite structure according to claim 1, characterized in that, In step S2, the amount of W@Bi2O3 core-satellite structure composite powder in the X / γ ray shielding compound is 30% to 60% of the total mass of the X / γ ray shielding compound.

7. The method for preparing the nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material according to claim 1, characterized in that, In step S3, the surface pretreatment process is as follows: flake-shaped hexagonal boron nitride powder is added to ethanol or an ethanol-water solution containing a silane coupling agent, stirred and dispersed at room temperature to 60°C for 30–90 min, and then dried at 80–110°C to constant weight to obtain surface-pretreated flake-shaped hexagonal boron nitride powder; in the neutron shielding compound, the filling amount of the flake-shaped hexagonal boron nitride powder is 10%–30% of the total mass of the neutron shielding compound.

8. The method for preparing the rubber-based functional composite material reinforced with inorganic fillers for a nuclear-satellite structure according to claim 1, characterized in that, In steps S2 and S3, the vulcanizing compounding agent comprises a vulcanizing agent, an activator, and an accelerator; the vulcanizing agent is sulfur, the activator includes zinc oxide and stearic acid, and the accelerator is one or more of sulfenamides and thiazoles; based on 100 parts by weight of natural rubber matrix, the amount of stearic acid is 1-3 parts by weight, the amount of zinc oxide is 3-6 parts by weight, the amount of sulfur is 1.0-2.5 parts by weight, and the amount of accelerator is 0.5-1.5 parts by weight; the antioxidant is one or more of amines and hindered phenols, and the amount of antioxidant is 0.5-2.0 parts by weight.

9. A rubber-based functional composite material reinforced with inorganic fillers in a nuclear-satellite structure, characterized in that, The rubber-based functional composite material is prepared by the preparation method described in any one of claims 1-8. It is a lead-free flexible thin-layer structure that has both X / γ-ray and neutron shielding properties and bidirectional equivalent shielding capability. The bidirectional equivalent shielding capability refers to the relative deviation of the shielding efficiency measured on both sides of the material being ≤5% when X / γ-rays and thermal neutrons are incident perpendicularly from the front and back sides of the shielding material, respectively, under the test conditions of the same ray energy and the same sample thickness.

10. The nuclear-satellite structure inorganic filler-reinforced rubber-based functional composite material according to claim 9, characterized in that, The total thickness of the inorganic filler-reinforced rubber-based functional composite material for the nuclear-satellite structure is 0.8 mm to 1 mm; wherein, the thickness ratio of the upper neutron shielding layer, the middle X / γ ray shielding layer, and the lower neutron shielding layer is (0.5 to 2):1:(0.5 to 2).

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