An organic-inorganic hybrid enhanced neutron and gamma-ray composite shielding structural material

Abstract

The present invention discloses an organic-inorganic hybrid reinforced neutron and gamma-ray composite shielding structural material, and relates to the field of composite shielding materials for nuclear radiation protection and preparation methods thereof. The neutron and gamma-ray composite structural shielding material refers to a composite material formed by casting or hot pressing in a certain mass ratio in the presence of a polymer resin and an auxiliary agent, comprising bamboo fiber containing an organic component, glass fiber containing an inorganic component, and an organic-inorganic hybridized rare earth metal organic framework material. The porosity and organic-inorganic hybrid characteristics of the rare earth metal organic framework material increase the compatibility between the components, so that the synthesized composite material has a higher rare earth metal content and dispersibility, and has higher mechanical properties, and has both neutron shielding and gamma-ray shielding capabilities.

Description

Technical Field

[0001] The invention belongs to the field of nuclear radiation protection and ray shielding materials, and specifically relates to an organic-inorganic hybrid enhanced neutron and gamma ray composite shielding structural material. Background Art

[0002] With the rapid development of nuclear energy and nuclear reactor technology, issues related to nuclear radiation safety and nuclear radiation protection have attracted widespread attention from more and more people. In order to strengthen the radiation protection of operators who have been engaged in radiation equipment maintenance and accident rescue for a long time, the development of shielding composite materials for protective equipment has extremely important scientific research significance and economic value. Neutron radiation and gamma-ray radiation are the main components of nuclear reactor radiation. Generally speaking, after the shielding effect of the inner structural material of the nuclear reactor, the neutrons that come into direct contact with humans have been slowed down into low-energy neutrons. Therefore, for neutron shielding, the lower the atomic number, the more valuable the material, because low-energy neutrons tend to elastically collide with the nucleus and continue to be slowed down into thermal neutrons, and finally absorbed by elements with a large neutron absorption cross-section to achieve neutron shielding; gamma rays are a kind of photon, and its shielding mainly depends on the interaction and attenuation with electrons. Therefore, for gamma-ray shielding, elements with higher atomic numbers and greater densities have more advantages, such as heavy metal materials such as lead and tungsten. Based on these considerations, the material with both neutron and gamma-ray shielding properties should be a combination of light elements and heavy elements.

[0003] However, due to differences in compatibility, the ability to combine light elements with heavy elements needs to be improved. Poor compatibility will lead to lower content and dispersion of heavy metal elements in polymer structural materials, or lower content and dispersion of organic components in metal structural materials, resulting in poor stability of composite shielding structural materials and uneven neutron and gamma-ray shielding performance. Therefore, the development of organic-inorganic hybrid enhanced neutron and gamma-ray composite shielding structural materials has practical value, which is conducive to optimizing the comprehensive shielding performance of neutrons and gamma rays, and developing new shielding materials with integrated structural shielding. Summary of the invention

[0004] The technical problem to be solved by the present invention is: through rational design and synthesis of rare earth metal organic framework materials, utilizing their porosity and organic-inorganic hybrid characteristics, solving the compatibility problem between metal elements with high atomic numbers and hydrogen elements with low atomic numbers, and obtaining a composite shielding structure material with both high neutron shielding performance and gamma-ray shielding performance.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An organic-inorganic hybrid reinforced neutron and gamma ray composite shielding structural material, the composite shielding material comprising: bamboo fiber, glass fiber, rare earth metal organic framework material, polymer resin, and additives;

[0007] Bamboo fiber: 100-200 parts

[0008] Glass fiber: 100-200 parts

[0009] Rare earth metal organic framework materials: 10-100 copies

[0010] Polymer resin: 10-500 parts

[0011] Additives: 1-10 parts

[0012] An organic-inorganic hybrid enhanced neutron and gamma-ray composite shielding structural material, the preparation method of which comprises the following steps: pre-synthesizing rare earth metal organic framework materials containing different rare earth elements and different size morphologies; fully mixing the rare earth metal organic framework materials with bamboo fiber, glass fiber, and polymer resin in a mass ratio of 1:10 to 10:1; adding an auxiliary agent in a mass ratio of 1:10 to the rare earth metal organic framework material, fully mixing, and pouring the mixed sample into a mold for drying or hot pressing.

[0013] As a preferred technical solution of the present invention: the rare earth metal organic framework material refers to a porous coordination polymer containing rare earth metals obtained by coordination polymerization of rare earth metals and their oxygen cluster structures as metal nodes with organic carboxylate ligands. Different rare earth elements include Gd, Ce, Sm, Tb, and different size morphologies include granular, rod-shaped, needle-shaped, etc.

[0014] As a preferred technical solution of the present invention: the bamboo fiber is bamboo pulp fiber, the component of the glass fiber is SiO2, and the polymer resin is epoxy resin, phenolic resin or polyurethane with supporting and bonding effects;

[0015] As a preferred technical solution of the present invention: the sufficient mixing refers to mixing the rare earth metal organic framework material with the polymer resin and other additives by high-speed stirring or ultrasonic mixing, and mixing with the bamboo fiber and the glass fiber by kneading.

[0016] As a preferred technical solution of the present invention: the auxiliary agent refers to a boron compound, a lead compound, a mildew preventer, a flame retardant or a combination thereof.

[0017] As a preferred technical solution of the present invention: it specifically includes the following steps:

[0018] (1) Select different rare earth metal salts and different organic ligands to prepare and synthesize rare earth metal organic framework materials of different types, sizes and morphologies, and use methanol, ethanol, water and other small molecules to fully wash and dry them to fully remove the unreacted raw materials and other small molecule compounds remaining in the pores of the rare earth metal organic framework materials;

[0019] (2) subjecting the rare earth metal organic framework material obtained in step (1) to high-speed mechanical stirring or ultrasonic mixing with a polymer resin and other additives, and continuing to knead the mixture with bamboo fiber and glass fiber until they are fully mixed;

[0020] (3) pouring a uniformly mixed mixture of rare earth metal organic framework material, bamboo fiber, glass fiber, polymer resin, and additive into a mold, and obtaining a molded organic-inorganic hybrid reinforced composite shielding structure material by hot pressing or heating solvent volatilization;

[0021] (4) Conduct various structural characterizations and neutron and gamma-ray shielding performance tests on the successfully prepared organic-inorganic hybrid reinforced composite shielding materials to optimize their neutron and gamma-ray shielding performance and mechanical properties.

[0022] The present invention relates to the method as described above, wherein the rare earth metal organic framework material includes but is not limited to Gd 3+ 、Ce 4+ 、Sm 3+ , Tb 3+ Gd-BDC, Ce-BDC, Sm-BDC, Tb-BDC, Gd-BTC, Ce-BTC, Sm-BTC, Tb-BTC, and other Gd-BDCs formed by self-assembly with terephthalic acid (H2BDC) and trimesic acid (H3BTC) 3+ 、Ce 4+ 、Sm 3+ , Tb 3+ Other types of porous Gd-MOF, Ce-MOF, Sm-MOF, Tb-MOF materials are obtained by coordination polymerization of rare earth metal ions and other organic carboxylate ligands. Rare earth metal organic framework materials are porous crystalline materials obtained by coordination self-assembly of rare earth metal ions and organic ligands containing multi-functional groups. They have both inorganic and organic properties and are a bridge between inorganic and organic materials (see Appendix Figure 1 ). By regulating the metal ion / organic ligand / solvent ratio and reaction temperature, the synthesis of rare earth metal organic framework materials of different sizes and morphologies can be achieved.

[0023] The present invention relates to the method as described above, wherein the drying can be natural drying, oven drying, or drying without heating or with heating under vacuum conditions, and the drying temperature is in principle not higher than the decomposition temperature of the prepared material.

[0024] The present invention relates to the method as described above, wherein the auxiliary agent is used to improve the mildew resistance, flame retardancy and other properties of the composite shielding structure material. Professional technicians in this field can easily determine its composition and content based on their knowledge. The amount of the auxiliary agent contained in the composite material does not exceed 10 parts by weight per 100 parts by weight of the rare earth metal organic framework material.

[0025] The present invention relates to the method as described above, wherein the composite casting molding of the rare earth metal organic framework material and the mixture of bamboo fiber, glass fiber, polymer resin and auxiliary agent is obtained by vacuuming and de-vacuuming in a vacuum drying oven under heating conditions for 3 times, then heating and drying for 1 hour, and then demolding, wherein the heating temperature is 50-100°C.

[0026] The present invention relates to the method as described above, wherein the composite hot pressing molding steps of the rare earth metal organic framework material and the mixture of bamboo fiber, glass fiber, polymer resin and auxiliary agent are: mixing - heating calendering molding - pressurized cooling - demoulding, wherein the heating temperature is 50-100°C and the pressure is 0.5-10MPa.

[0027] In the present invention, the terms "shielding structural material", "neutron and gamma ray shielding material", "composite shielding material" and the like may be used interchangeably.

[0028] In the present invention, the terms "rare earth metal organic framework material", "rare earth metal organic framework material" and "rare earth MOFs" can be used interchangeably.

[0029] In the present invention, when referring to the ratio or % of amount, unless otherwise specified, it means the weight ratio or weight percentage.

[0030] The present invention also relates to the mechanical properties and uses of a novel composite shielding structure material obtained by the method of the present invention. The prepared organic-inorganic hybrid reinforced composite shielding structure material has excellent comprehensive shielding performance of neutron and gamma ray shielding, wherein the porous characteristics of the rare earth metal organic framework material are also conducive to the orientation of the polymer resin and the regulation of the growth environment, and are conducive to obtaining high mechanical properties.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) Rare earth metal organic framework materials are constructed by the coordination of rare earth metal ions and organic ligands, and then compounded with bamboo fibers, glass fibers, polymer resins, and additives. Based on the porosity and organic-inorganic hybrid characteristics of rare earth metal organic framework materials, and in accordance with the principle of like dissolves like, rare earth metal organic framework materials have good compatibility with glass fibers containing inorganic components, additives, etc., and also have good compatibility with bamboo fibers containing organic components, polymer resins, etc. Therefore, this method is conducive to increasing the content and dispersibility of rare earth metals in the composite shielding material, enhancing the compatibility of organic bamboo fibers and inorganic glass fibers in the mixed system, and thus improving the mechanical properties;

[0033] (2) Rare earth metals generally have large atomic numbers and have excellent γ-ray shielding capabilities; based on Gd 3+ 、Ce 4+ 、Sm 3+ , Tb 3+ Rare earth metals have a large thermal neutron absorption cross section; therefore, the composite shielding material system has both excellent neutron shielding performance and gamma-ray shielding performance;

[0034] (3) The stability of polymer resin is limited. The introduction of bamboo fiber and glass fiber is beneficial to enhance the thermal stability and chemical stability of polymer resin, thereby improving the stability of composite shielding materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 The figure is a schematic diagram of the synthesis process route of the rare earth metal organic framework material of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] Presynthesis of Gd-BTC: 2.7 mL of 0.05 M 1,2,4-benzenetricarboxylic acid trisodium aqueous solution and 2.7 mL of 0.05 M GdCl3·6H2O aqueous solution were added to 200 mL of ethanol solution, respectively. After stirring evenly, ultrasonic treatment was performed at room temperature for 3.0 h. The Gd-BTC solid sample was collected by centrifugation or filtration, washed with deionized water and anhydrous ethanol for 3 times, and dried in a vacuum at 60°C.

[0040] Composite ratio of composite shielding structure materials:

[0041] Bamboo fiber: 100 parts

[0042] Glass fiber: 100 parts

[0043] Gd-BTC: 50 copies

[0044] Epoxy resin emulsion: 50 parts

[0045] Additives: 5 parts

[0046] The additive is a lead compound such as lead oxide, which is used to shield secondary gamma-ray radiation. The composite material is formed by hot pressing. After the components are mixed evenly, they are filled into a preheated mold at a heating temperature of 80°C. After the mold is closed, the pressure is increased to 10MPa. The mold is cooled to room temperature under pressure, opened and demolded, and a composite shielding structure material with the same shape as the mold is obtained.

[0047] Example 2

[0048] Gd-BTC was pre-synthesized according to the method of Example 1, and several components were compounded according to the following ratio:

[0049] Bamboo fiber: 100 parts

[0050] Glass fiber: 100 parts

[0051] Gd-BTC: 50 copies

[0052] Epoxy resin emulsion: 300 parts

[0053] Additives: 5 parts

[0054] The additives are 8 parts of lead compound, which is used to shield secondary gamma-ray radiation, and 2 parts of magnesium hydroxide, which is used as a flame retardant. The components are uniformly mixed according to the proportion, and the mixture is quickly stirred to obtain a uniform viscous mixture, which is poured into a polytetrafluoroethylene mold, heated to 80°C, and slowly vacuumed for 3 minutes, then stopped and filled with air, and the vacuum-filling-air cycle is repeated 5 times, and the temperature is raised to 100°C, dried for 1 hour, cooled to room temperature and demoulded.

[0055] Example 3

[0056] Presynthesis of Tb-BTC: In a mixed solution of N,N-dimethylformamide (40 mL), ethanol (40 mL) and water (32 mL), Tb(NO3)3·6H2O (1.266 g) and H3BTC (0.2 g) were added to the ethanol solution in sequence. After stirring evenly, ultrasonic reaction was carried out at 60°C for 3.0 h. The Tb-BTC solid sample was collected by centrifugation or filtration, washed three times with anhydrous ethanol, and dried in a vacuum at 60°C.

[0057] Composite ratio of composite shielding structure materials:

[0058] Bamboo fiber: 100 parts

[0059] Glass fiber: 100 parts

[0060] Tb-BTC: 50

[0061] Epoxy resin emulsion: 50 parts

[0062] Additives: 5 parts

[0063] The additives are lead compounds such as 3 parts of lead oxide and boron compounds such as 2 parts of boron carbide, which are used to shield secondary gamma-ray radiation and increase neutron absorption capacity. The material is formed by hot pressing. After the components are mixed evenly, they are filled into the preheated mold at a heating temperature of 80°C. After the mold is closed, the pressure is increased to 10MPa. The mold is cooled to room temperature under pressure and the mold is opened and demolded to obtain a composite shielding structure material with the same shape as the mold.

[0064] Example 4

[0065] Tb-BTC was pre-synthesized according to the method of Example 3, and several components were compounded according to the following ratios:

[0066] Bamboo fiber: 100 parts

[0067] Glass fiber: 100 parts

[0068] Tb-BTC: 50

[0069] Epoxy resin emulsion: 300 parts

[0070] Additives: 5 parts

[0071] The additives are 2 parts of lead compounds such as lead oxide and 2 parts of boron compounds such as boron carbide, which are used to shield secondary gamma-ray radiation and increase neutron absorption capacity, and 1 part of magnesium hydroxide, which is used as a flame retardant. The components are uniformly mixed in proportion, stirred quickly to obtain a uniform viscous mixture, poured into a polytetrafluoroethylene mold, heated to 80°C, slowly vacuumed for 3 minutes, then stopped, filled with air, and cycled vacuum-filled with air for 5 times, heated to 100°C, dried for 1 hour, cooled to room temperature and demoulded.

[0072] Comparative Example

[0073] The components are compounded according to the following ratios:

[0074] Bamboo fiber: 100 parts

[0075] Glass fiber: 100 parts

[0076] Rare earth metal organic framework materials: 0

[0077] Epoxy resin emulsion: 50 parts

[0078] Additives: 0

[0079] The material is formed by hot pressing. After the components are mixed evenly, they are filled into the preheated mold and heated to 80°C. After the mold is closed, the pressure is increased to 10MPa. The mold is cooled to room temperature under pressure, and then the mold is opened and demolded to obtain a composite shielding structure material with the same shape as the mold.

[0080] The shielding performance of the samples obtained in Examples 1-4 and the comparative example was tested, and the test results are shown in the following table. Among them, the thickness of the shielding structure material is 2 cm; a 0.0253 eV thermal neutron source is used to simulate the neutron irradiation environment of the composite material, and the neutron shielding performance is simulated by software, and the neutron shielding performance is obtained by converting the neutron injection transmittance ratio (I / I0); the gamma ray shielding ability is obtained by testing, mainly testing the shielding efficiency of each material at the two energy peaks of 121.78 KeV and 344.28 KeV.

[0081] Table 1. Comparison of neutron shielding performance and gamma-ray shielding performance of the samples of the embodiment and the comparative example

[0082]

[0083] Combining the above-mentioned various preparation methods, the results show that the shielding structure material composited with bamboo fiber, glass fiber, rare earth metal organic framework material, and polymer resin has excellent mechanical properties, which verifies the structural enhancement effect of bamboo fiber and glass fiber, and the mechanical enhancement effect of rare earth metal organic framework material with organic-inorganic hybrid characteristics. The neutron shielding performance of the shielding structure material is better than that of commonly used steel structure materials and concrete materials, and the gamma-ray shielding performance is comparable to that of commonly used steel structure materials and concrete materials, which proves the composition advantage of the shielding structure material. The results of the embodiment show that the organic-inorganic hybrid enhanced neutron and gamma-ray composite shielding structure material has good practical value.

[0084] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An organic-inorganic hybrid enhanced neutron and gamma-ray composite shielding structural material, characterized in that: Presynthesis of Tb-BTC: In a mixed solution of 40 mL N,N-dimethylformamide, 40 mL ethanol and 32 mL water, 1.266 g Tb(NO3)3·6H2O and 0.2 g H3BTC were added in sequence, stirred evenly, and then ultrasonically reacted at 60°C for 3.0 h. The solid sample of Tb-BTC was collected by centrifugation or filtration, washed with anhydrous ethanol for 3 times, and dried in a vacuum at 60°C. Composite ratio of composite shielding structural materials: Bamboo fiber: 100 parts Glass fiber: 100 parts Tb-BTC: 50 Epoxy resin emulsion: 50 parts Additives: 5 parts The additives are 3 parts of lead oxide and 2 parts of boron carbide, which are used to shield secondary gamma-ray radiation and increase neutron absorption capacity. The material is formed by hot pressing. After the components are mixed evenly, they are filled into a preheated mold at a heating temperature of 80°C. After the mold is closed, the mold is pressurized to 10MPa. The mold is cooled to room temperature under pressure, the mold is opened and demolded, and a composite shielding structure material with the same shape as the mold is obtained.

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