Bismuth oxide-based epoxy resin composite material with radiation shielding function as well as preparation method and application of bismuth oxide-based epoxy resin composite material

Abstract

The invention provides a bismuth oxide-based epoxy resin composite material with a radiation shielding function as well as a preparation method and application of the bismuth oxide-based epoxy resin composite material. According to the preparation method disclosed by the invention, the bismuth oxide is subjected to surface modification, and after surface grafting modification by the coupling agent, the surface of the bismuth oxide is changed from strong hydrophilicity to strong hydrophobicity, so that the dispersity and interfacial compatibility of the bismuth oxide in an organic medium are remarkably improved. Secondly, preparing the composite material from the modified bismuth oxide, epoxy resin and a curing agent through a mechanical blending-vacuum defoaming combined process. On one hand, bismuth oxide, epoxy resin and a curing agent are uniformly mixed through mechanical blending; on the other hand, bubbles generated in the blending process are removed through vacuum negative pressure. The bismuth oxide in the composite material is uniformly distributed, no bubble exists in the body, and the surface is smooth and complete, so that the composite material has excellent gamma-ray shielding performance and good mechanical property. The process is simple, the yield is high, the product property is stable, and good economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation shielding materials, and in particular to a bismuth oxide-based epoxy resin composite material with radiation shielding function, and a preparation method and application thereof. Background Art

[0002] Gamma rays are high-frequency, high-energy electromagnetic waves. Since their discovery, they have been widely used in food irradiation, radiotherapy, product sterilization and the nuclear industry. However, due to their strong penetrating power and high energy, direct exposure to these rays may cause serious harm, such as cancer and permanent infertility, and even endanger life. Practitioners involved in gamma ray operations must follow the necessary safety precautions to ensure effective radiation protection.

[0003] Generally speaking, high-Z elements (atomic number greater than 56) have significant radiation absorption capabilities and can effectively reduce radiation doses through the photoelectric effect, Compton scattering, and electron pair effect. Lead (Pb) is an easily available and relatively cheap high-Z metal that is often used in radiation protection (such as protective clothing and radiation-proof plates in the nuclear industry). However, the high specific gravity of lead (ρ = 11.3437 g / cm 3 ) and biological toxicity seriously affect the wearing time and comfort of workers, and there is a risk of lead poisoning. In addition, lead has an absorption blind spot in the energy range of 70-90keV, which leads to a significant reduction in its shielding efficiency. The pure metal used as shielding material is too heavy, and the concrete occupies a large area and is not easy to move, which cannot meet the application requirements. With the continuous development of industrial technology, the requirements for gamma-ray shielding materials are gradually tending to be lightweight, harmless, and high shielding efficiency. The current mainstream method is to add high-Z metal or oxide powders as fillers to polymer materials (such as epoxy resins) to manufacture lightweight composite materials with excellent radiation shielding properties. However, the practical application of these powders faces many challenges, including agglomeration, poor interface compatibility, and insufficient mechanical properties. In addition, in the actual production process, the fillers tend to agglomerate quickly, resulting in a serious decrease in the mechanical properties and radiation shielding properties of the composite materials.

[0004] Bismuth (Bi) with an atomic number of 83 is an ideal substitute for lead due to its stability, non-toxicity to organisms, and excellent gamma-ray shielding performance. However, it also has the characteristics of high density and heavy weight, which leads to problems such as fast powder sedimentation, agglomeration, and poor interfacial compatibility between powder and resin in the preparation of composite materials, resulting in poor mechanical properties and greatly reduced radiation shielding performance in practical applications.

[0005] Therefore, it is necessary to use surface modification technology to modify the powder, improve its dispersibility and interface compatibility in the organic system, and then prepare lightweight composite materials with good thermal stability, mechanical properties and radiation shielding properties through a molding process. Summary of the invention

[0006] The present invention provides a bismuth oxide-based epoxy resin composite material with radiation shielding function, a preparation method and application thereof, and aims to solve the above-mentioned problems existing in the background technology.

[0007] In order to achieve the above-mentioned purpose, the embodiment of the present invention provides a bismuth oxide-based epoxy resin composite material with radiation shielding function and its preparation method and application. The present invention adopts bismuth oxide (Bi2O3) powder with excellent radiation shielding performance, stable properties and no biological toxicity as filler to replace traditional lead oxide (PbO). First, a silane coupling agent is used to graft and modify the surface of bismuth oxide powder to change its surface properties, make it hydrophobic and oleophilic, and achieve its long-term and stable dispersion in the resin system; secondly, the surface-modified bismuth oxide powder is mixed with epoxy resin and curing agent by a mechanical blending-vacuum degassing combined process, poured into a mold, and a bismuth oxide-based epoxy resin composite material (Bi2O3@epoxy resin) is prepared by a curing procedure. Compared with traditional radiation shielding materials, the filler distribution is more uniform, the mechanical properties are better, the thermal stability is better, and the gamma-ray shielding efficiency is higher. This technical invention is helpful to realize the high-value utilization of my country's bismuth resources, and provides strong help for my country's nuclear industry, radiation medicine and other fields, and provides strong protection for relevant practitioners.

[0008] An embodiment of the present invention provides a method for preparing a bismuth oxide-based epoxy resin composite material having a radiation shielding function, comprising the following steps:

[0009] S1: using a silane coupling agent to graft-modify the surface of bismuth oxide powder to obtain surface-modified bismuth oxide powder;

[0010] S2: The surface-modified bismuth oxide powder is mixed evenly with bisphenol A epoxy resin and curing agent through a mechanical blending-vacuum degassing combined process, and then poured into a mold, and a bismuth oxide-based epoxy resin composite material with radiation shielding function is prepared through a curing process.

[0011] Preferably, step S1 specifically includes the following process:

[0012] S1.1: 80% to 95% anhydrous ethanol and 5% to 20% ultrapure water are mixed in a volume ratio to obtain a mixed solution, and the pH value of the mixed solution is adjusted to between 3 and 4 with 1 mol / L dilute hydrochloric acid to obtain a hydrolyzate; wherein the pH value is generally within the range of 3.5±0.3.

[0013] S1.2: Add 0.5% to 3% of silane coupling agent to the prepared hydrolyzate, stir for 20 to 60 minutes, slowly add bismuth oxide powder after the silane coupling agent is completely hydrolyzed, ultrasonically disperse at room temperature for 20 to 60 minutes, transfer the suspension to a round-bottom flask, heat to 60 to 90°C, and reflux at a constant temperature with magnetic stirring for 3 to 6 hours. The modified product is separated by centrifugation, washed several times with an appropriate amount of anhydrous ethanol, and dried in an oven at 60°C to constant weight to obtain the modified bismuth oxide powder. Among them, the preferred amount of silane coupling agent is 0.8% to 3%; the preferred heating temperature is generally 75 to 85°C;

[0014] Preferably, step S2 specifically includes the following process:

[0015] The epoxy resin is placed in an oven at 80°C and heated for 30 minutes, the dried epoxy resin is weighed in a three-necked flask, the temperature is maintained at 40-70°C, 20%-50% of the surface-modified bismuth oxide powder is added, the bubbles are removed by vacuum mechanical stirring for 30-120 minutes, 1 / 2-1 / 5 of the curing agent is added, and the vacuum stirring is continued for 30 minutes until the reaction is completed, the mixed fluid after the reaction is poured into a silicone mold, and finally placed in a vacuum drying oven, and the epoxy resin is cured according to the temperature increase program of 80°C pre-curing for 2 hours, 110°C curing for 3 hours, and 130°C curing for 4 hours. After curing, demolding is performed to obtain a bismuth oxide-based epoxy resin composite material with radiation shielding function. Among them, the surface-modified bismuth oxide powder is preferably added in an amount of 30%-50%; the temperature is preferably maintained at 40-50°C; and the vacuum mechanical stirring is preferably used to remove bubbles for 50-90 minutes.

[0016] Preferably, the particle size of the bismuth oxide powder is less than 400-800 nm. More preferably, the particle size of the Bi2O3 powder is generally less than 600 nm.

[0017] Preferably, the bisphenol A type epoxy resin includes at least one of E51, E55, E44, E42, and E35, but is not limited to the above-mentioned epoxy resins.

[0018] Preferably, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane (KH550), γ-methacryloxypropyltrimethoxysilane (KH570), hexadecyltrimethoxysilane (KH1631), and vinyltrimethoxysilane (A171), but is not limited to the coupling agents mentioned above.

[0019] Preferably, the curing agent includes one or two of polyetheramine, polyamide, polythiol and fatty amine.

[0020] Based on a general inventive concept, an embodiment of the present invention provides a bismuth oxide-based epoxy resin composite material having a radiation shielding function obtained by the above-mentioned preparation method.

[0021] Preferably, bismuth oxide is evenly dispersed in the composite material, and the tensile properties and bending properties are significantly improved; the composite material has an excellent shielding effect on 662keV gamma rays.

[0022] An embodiment of the present invention provides an application of a bismuth oxide-based epoxy resin composite material having a radiation shielding function obtained by the above preparation method.

[0023] Reaction mechanism:

[0024] The present invention first performs surface modification on bismuth oxide. After the surface of bismuth oxide powder is modified by coupling agent surface grafting, its surface changes from strong hydrophilicity to strong hydrophobicity, which significantly improves its dispersibility and interface compatibility in organic media. Secondly, the modified bismuth oxide, epoxy resin and curing agent are prepared through a mechanical blending-vacuum degassing combined process to prepare a composite material. On the one hand, bismuth oxide, epoxy resin and curing agent are mixed evenly by mechanical blending; on the other hand, the bubbles generated during the blending process are removed by vacuum negative pressure to prepare a composite material with uniform distribution of bismuth oxide, no bubbles in the body and smooth and complete surface, so that it has excellent gamma-ray shielding performance and good mechanical properties. Compared with traditional technology, the present invention has a simple process, bismuth oxide is evenly dispersed in the resin system, the yield is high in the actual production process, the product properties are stable, and it has good economic and environmental benefits.

[0025] The above scheme of the present invention has the following beneficial effects:

[0026] (1) The present invention innovates the shielding material system, replacing the traditional PbO with Bi2O3, which is non-biotoxic, has excellent radiation shielding performance and low specific gravity, and combines it with epoxy resin to form a lightweight radiation shielding composite material with excellent radiation shielding performance and mechanical properties. Among them, the surface modification method of Bi2O3 powder is innovative, using silane coupling agent as a modifier, and a suitable proportion of ethanol-water mixed solution as a coupling agent hydrolyzing liquid, and a wet modification process is used to graft and modify the surface of Bi2O3 powder to make it hydrophobic and oleophilic. Compared with unmodified Bi2O3 and reported modified Bi2O3 powder, the coupling agent of this patent hydrolyzes more rapidly, the modified powder is more hydrophobic, and it is endowed with long-term dispersion and interface compatibility in the resin system, avoiding the material inhomogeneity caused by the sedimentation of Bi2O3 powder in epoxy resin during the subsequent composite material preparation process.

[0027] (2) The present invention innovates the preparation method of composite materials, adopts the mechanical blending-vacuum degassing combined process to prepare Bi2O3@epoxy resin composite materials, the modified Bi2O3 can be evenly dispersed in the resin system by mechanical blending, and the bubbles generated during the blending process can be discharged by vacuum degassing, so that the Bi2O3 in the final product is evenly dispersed, there are no bubbles inside and on the surface of the composite material, and the mechanical properties and radiation shielding properties of the product are excellent. Compared with the traditional preparation process, the present invention does not need to add additional chemical additives such as defoaming agents, the amount of chemical reagents used is small, the preparation process is simple, and the material preparation cost is lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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 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.

[0029] Figure 1 This is a contact angle picture of the unmodified Bi2O3 powder of Comparative Example 3 of the present invention;

[0030] Figure 2 This is a contact angle picture of Bi2O3 powder modified by A171 in Example 2 of the present invention;

[0031] Figure 3 is a cross-sectional SEM-EDS image of the composite material of Comparative Example 3 of the present invention;

[0032] Figure 4 This is a SEM-EDS image of the cross section of the composite material of Example 2 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0034] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0035] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0036] In view of the existing problems, the present invention provides a bismuth oxide-based epoxy resin composite material with radiation shielding function, a preparation method and application thereof.

[0037] An embodiment of the present invention provides a method for preparing a bismuth oxide-based epoxy resin composite material having a radiation shielding function, comprising the following steps:

[0038] S1: using a silane coupling agent to graft-modify the surface of bismuth oxide powder to obtain surface-modified bismuth oxide powder;

[0039] S2: The surface-modified bismuth oxide powder is mixed evenly with bisphenol A epoxy resin and curing agent through a mechanical blending-vacuum degassing combined process, and then poured into a mold, and a bismuth oxide-based epoxy resin composite material with radiation shielding function is prepared through a curing process.

[0040] Preferably, step S1 specifically includes the following process:

[0041] S1.1: 80% to 95% anhydrous ethanol and 5% to 20% ultrapure water are mixed in a volume ratio to obtain a mixed solution, and the pH value of the mixed solution is adjusted to between 3 and 4 with 1 mol / L dilute hydrochloric acid to obtain a hydrolyzate; wherein the pH value is generally within the range of 3.5±0.3.

[0042] S1.2: Add 0.5% to 3% of silane coupling agent to the prepared hydrolyzate, stir for 20 to 60 minutes, slowly add bismuth oxide powder after the silane coupling agent is completely hydrolyzed, ultrasonically disperse at room temperature for 20 to 60 minutes, transfer the suspension to a round-bottom flask, heat to 60 to 90°C, and reflux at a constant temperature with magnetic stirring for 3 to 6 hours. The modified product is separated by centrifugation, washed several times with an appropriate amount of anhydrous ethanol, and dried in an oven at 60°C to constant weight to obtain the modified bismuth oxide powder. Among them, the preferred amount of silane coupling agent is 0.8% to 3%; the preferred heating temperature is generally 75 to 85°C;

[0043] Preferably, step S2 specifically includes the following process:

[0044] The epoxy resin is placed in an oven at 80°C and heated for 30 minutes, the dried epoxy resin is weighed in a three-necked flask, the temperature is maintained at 40-70°C, 20%-50% of the surface-modified bismuth oxide powder is added, the bubbles are removed by vacuum mechanical stirring for 30-120 minutes, 1 / 2-1 / 5 of the curing agent is added, and the vacuum stirring is continued for 30 minutes until the reaction is completed, the mixed fluid after the reaction is poured into a silicone mold, and finally placed in a vacuum drying oven, and the epoxy resin is cured according to the temperature increase program of 80°C pre-curing for 2 hours, 110°C curing for 3 hours, and 130°C curing for 4 hours. After curing, demolding is performed to obtain a bismuth oxide-based epoxy resin composite material with radiation shielding function. Among them, the surface-modified bismuth oxide powder is preferably added in an amount of 30%-50%; the temperature is preferably maintained at 40-50°C; and the vacuum mechanical stirring is preferably used to remove bubbles for 50-90 minutes.

[0045] Preferably, the particle size of the bismuth oxide powder is less than 400-800 nm. More preferably, the particle size of the Bi2O3 powder is generally less than 600 nm.

[0046] Preferably, the bisphenol A type epoxy resin includes at least one of E51, E55, E44, E42, and E35, but is not limited to the above-mentioned epoxy resins.

[0047] Preferably, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane (KH550), γ-methacryloxypropyltrimethoxysilane (KH570), hexadecyltrimethoxysilane (KH1631), and vinyltrimethoxysilane (A171), but is not limited to the coupling agents mentioned above.

[0048] Preferably, the curing agent includes one or two of polyetheramine, polyamide, polythiol and fatty amine.

[0049] Based on a general inventive concept, an embodiment of the present invention provides a bismuth oxide-based epoxy resin composite material having a radiation shielding function obtained by the above-mentioned preparation method.

[0050] Preferably, bismuth oxide is evenly dispersed in the composite material, and the tensile properties and bending properties are significantly improved; the composite material has an excellent shielding effect on 662keV gamma rays.

[0051] An embodiment of the present invention provides an application of a bismuth oxide-based epoxy resin composite material having a radiation shielding function obtained by the above preparation method.

[0052] In summary, the present invention adopts Bi2O3 with good radiation shielding performance, non-toxicity and low specific gravity as filler to replace traditional PbO to prepare Bi2O3@epoxy resin composite materials. First, the surface properties of Bi2O3 are changed by surface grafting of coupling agent, and the long-term dispersibility and interface compatibility of Bi2O3 in the resin are enhanced, which avoids the problems of uneven composition and properties of composite materials caused by Bi2O3 sedimentation in the actual production process of composite materials. The modified Bi2O3 is then compounded with epoxy resin through a mechanical blending-vacuum degassing combined process to prepare Bi2O3@epoxy resin composite materials. The preparation method of the composite material is simple, Bi2O3 has good dispersibility in the resin system, the composite material is lightweight, the mechanical properties and radiation shielding performance are excellent, and the product properties are uniform. This technical invention is conducive to the high-value utilization of my country's bismuth resources, and provides strong assistance to my country's nuclear industry, radiation medicine and other fields, and provides strong protection for relevant practitioners.

[0053] The comparative example of the present invention uses commercially available Bi2O3 powder and PbO powder with a particle size distribution of 500-700 nm. The embodiment uses Bi2O3 powder modified by a coupling agent. The basic parameters of the powder surface modification and the preparation of the composite material are shown in Tables 1 and 2.

[0054] Table 1

[0055]

[0056] Table 2

[0057] sample parameter <![CDATA[Addition amount of modified Bi2O3]]> 0％～50％ <![CDATA[Addition amount of unmodified Bi2O3 or PbO]]> 0％～50％ Epoxy resin Bisphenol A epoxy resin E51, E55, E44, E42, E35 Curing agent 1 / 2 to 1 / 5 of the mass of epoxy resin (polyetheramine D230, polythiol 309)

[0058] The following will describe the invention through specific embodiments.

[0059] Example 1

[0060] This embodiment uses modified Bi2O3 powder with an average particle size of 400nm, bisphenol A epoxy resin E55, and polythiol 309 as a curing agent. The specific implementation process includes:

[0061] ① Preparation of coupling agent hydrolysis solution: 90% anhydrous ethanol and 10% ultrapure water were mixed according to volume fraction to obtain a mixed solution, and then the pH value of the mixed solution was adjusted to 3 with dilute hydrochloric acid (concentration of 1 mol / L) to prepare a coupling agent hydrolysis solution;

[0062] ② Coupling agent grafting process, add 1% (relative to the mass of Bi2O3 powder) of silane coupling agent KH550 to the prepared hydrolyzate and stir for 40 minutes. After the silane coupling agent is completely hydrolyzed, weigh the Bi2O3 powder, slowly add it to the hydrolyzate, and ultrasonically disperse it at room temperature for 30 minutes. Subsequently, transfer the suspension to a round-bottom flask, heat it to 90°C, and reflux it at a constant temperature with magnetic stirring for 3 hours. The modified product is separated by centrifugation and washed several times by centrifugation with an appropriate amount of anhydrous ethanol. Dry it in an oven at 60°C to constant weight to obtain the modified Bi2O3 powder (remember M-Bi2O3). The contact angle of the modified M-Bi2O3 is increased from 6° to 118°, and the sedimentation time of M-Bi2O3 in the organic medium is increased from the original 2h to 14h.

[0063] ③ Preparation of M-Bi2O3@epoxy resin composite material: Epoxy resin E51 was placed in an oven at 80℃ and heated for 30min. After its viscosity was reduced, epoxy resin was weighed in a three-necked flask and the temperature was maintained at 45℃. Then, 30% mass fraction (relative to the mass of epoxy resin) of M-Bi2O3 powder was added respectively, and the bubbles were removed by vacuum mechanical stirring for 60min. Subsequently, 1 / 3 of the mass of epoxy resin was added as curing agent polythiol 309, and vacuum stirring was continued for 30min until the reaction was completed. The mixed fluid after the reaction was poured into a silicone mold, and finally placed in a vacuum drying oven. The epoxy resin was cured according to the temperature program of 80℃ pre-curing for 2h, 110℃ curing for 3h, and 130℃ curing for 4h. After curing, demolding was performed to obtain M-Bi2O3@epoxy resin (named EP3-1) composite material. The experimental results show that the tensile strength of the composite material is 52.43 MPa, the bending strength is 84.27 MPa, and the shielding efficiency of EP3-1 against 662 keV gamma rays is 1.33% (the shielding efficiency of a material with a thickness of 10 cm is calculated to be 48.83% using formula (1)). See Table 3 for details.

[0064] RSE=(1-e -μd )×100 (1)

[0065] In formula (1), μ is the linear attenuation coefficient of the composite material to γ ​​rays, cm -1 ; d is the thickness of the composite material, cm.

[0066] Example 2

[0067] This embodiment uses modified Bi2O3 powder with an average particle size of 500nm, bisphenol A epoxy resin E51, and polyetheramine D230 as a curing agent. The specific implementation process includes:

[0068] ① Preparation of coupling agent hydrolysis solution: 95% anhydrous ethanol and 5% ultrapure water were mixed according to volume fraction to obtain a mixed solution, and then the pH value of the mixed solution was adjusted to 4 with dilute hydrochloric acid (concentration of 1 mol / L) to prepare a coupling agent hydrolysis solution;

[0069] ② Coupling agent grafting process, add 2% (relative to the mass of Bi2O3 powder) of silane coupling agent A171 to the prepared hydrolyzate and stir for 40 minutes. After the silane coupling agent is completely hydrolyzed, weigh the Bi2O3 powder, slowly add it to the hydrolyzate, and ultrasonically disperse it at room temperature for 30 minutes. Subsequently, transfer the suspension to a round-bottom flask, heat it to 80°C, and reflux it at a constant temperature with magnetic stirring for 4 hours. The modified product is separated by centrifugation and washed several times by centrifugation with an appropriate amount of anhydrous ethanol. Dry it in an oven at 60°C to constant weight to obtain the modified Bi2O3 powder (remember M-Bi2O3). The contact angle of the modified M-Bi2O3 is increased from 6° to 139°, and the sedimentation time of M-Bi2O3 in the organic medium is increased from the original 2h to 18h.

[0070] ③ Preparation of M-Bi2O3@epoxy resin composite material: heat the epoxy resin in an oven at 80℃ for 30min. After its viscosity decreases, weigh the epoxy resin in a three-necked flask and maintain the temperature at 45℃. Then add 40% mass fraction (relative to the mass of epoxy resin) of M-Bi2O3 powder and stir in a vacuum machine to remove bubbles for 60min. Then add 1 / 3 of the mass of epoxy resin as curing agent polyetheramine D230 and continue to stir in a vacuum for 30min until the reaction is completed. Pour the mixed fluid after the reaction into a silicone mold and finally place it in a vacuum drying oven. According to the temperature program of 80℃ pre-curing for 2h, 110℃ curing for 3h, and 130℃ curing for 4h, the epoxy resin is cured. After curing, demolding is performed to obtain the M-Bi2O3@epoxy resin (named EP4-2) composite material. The experimental results show that the tensile strength of the composite material is 57.98 MPa, the bending strength is 91.03 MPa, and the shielding efficiency of EP4-2 against 662 keV gamma rays is 1.63% (the shielding efficiency of a material with a thickness of 10 cm is calculated to be 55.96% using formula (1)). See Table 3 for details.

[0071] Example 3

[0072] This embodiment uses modified Bi2O3 powder with an average particle size of 550nm, the epoxy resin uses bisphenol A epoxy resin E51, and the curing agent uses polyetheramine D230. The specific implementation process includes:

[0073] ① Preparation of coupling agent hydrolysis solution: 85% anhydrous ethanol and 15% ultrapure water were mixed according to volume fraction to obtain a mixed solution, and then the pH value of the mixed solution was adjusted to 3.5 with dilute hydrochloric acid (concentration of 1 mol / L) to prepare a coupling agent hydrolysis solution;

[0074] ② Coupling agent grafting process, add 2% (relative to the mass of Bi2O3 powder) of silane coupling agent KH570 to the prepared hydrolyzate and stir for 50 minutes. After the silane coupling agent is completely hydrolyzed, weigh the Bi2O3 powder, slowly add it to the hydrolyzate, and ultrasonically disperse it at room temperature for 30 minutes. Subsequently, transfer the suspension to a round-bottom flask, heat it to 85°C, and reflux it at a constant temperature with magnetic stirring for 5 hours. The modified product is separated by centrifugation and washed several times by centrifugation with an appropriate amount of anhydrous ethanol. Dry it in an oven at 60°C to constant weight to obtain the modified Bi2O3 powder (remember M-Bi2O3). The contact angle of the modified M-Bi2O3 is increased from 6° to 128°, and the sedimentation time of M-Bi2O3 in the organic medium is increased from the original 2h to 16h.

[0075] ③ Preparation of M-Bi2O3@epoxy resin composite material: heat the epoxy resin in an oven at 80℃ for 30min. After its viscosity decreases, weigh the epoxy resin in a three-necked flask and maintain the temperature at 45℃. Then add 50% mass fraction (relative to the mass of epoxy resin) of M-Bi2O3 powder and stir in a vacuum machine to remove bubbles for 80min. Then add 1 / 4 of the mass of epoxy resin as curing agent polyetheramine D230 and continue to stir in a vacuum for 30min until the reaction is completed. Pour the mixed fluid after the reaction into a silicone mold and finally place it in a vacuum drying oven. According to the temperature program of 80℃ pre-curing for 2h, 110℃ curing for 3h, and 130℃ curing for 4h, the epoxy resin is cured. After curing, demoulding is performed to obtain the M-Bi2O3@epoxy resin (named EP5-3) composite material. The experimental results show that the tensile strength of the composite material is 55.33 MPa, the bending strength is 87.42 MPa, and the shielding efficiency of EP5-3 against 662 keV gamma rays is 1.71% (the shielding efficiency of a material with a thickness of 10 cm is calculated to be 57.68% using formula (1)). See Table 3 for details.

[0076] Comparative Example 1

[0077] The epoxy resin of this comparative example adopts bisphenol A epoxy resin E51, the curing agent adopts polyetheramine D230, and no Bi2O3 is added. The specific implementation process includes:

[0078] First, epoxy resin E51 was placed in an oven at 80°C and heated for 30 minutes. After its viscosity was reduced, the epoxy resin was weighed in a three-necked flask and heated to 45°C. Then, polyetheramine D230 was added in an amount of 1 / 3 of the mass of the epoxy resin, and the bubbles were removed by vacuum mechanical stirring for 50 minutes until the reaction was completed. The mixed fluid after the reaction was poured into a silicone mold, and finally placed in a vacuum drying oven. The epoxy resin was cured according to the temperature increase program of 80°C pre-curing for 2 hours, 110°C curing for 3 hours, and 130°C curing for 4 hours. After curing, the epoxy resin (EP) material was demolded to obtain. The experimental results show that the tensile strength of the epoxy resin is 52.82MPa, the bending strength is 61.31MPa, and the shielding efficiency of the epoxy resin against 662keV gamma rays is 0.06% (the shielding efficiency of the material with a thickness of 10cm is calculated to be 2.95% using formula (1)). See Table 3 for details.

[0079] Comparative Example 2

[0080] This comparative example uses unmodified commercially available PbO powder with an average particle size of 500 nm, bisphenol A epoxy resin E51, and polyetheramine D230 as a curing agent. The specific implementation process includes:

[0081] First, the epoxy resin E51 was placed in an oven at 80°C and heated for 30 minutes. After its viscosity decreased, the epoxy resin was weighed in a three-necked flask and heated to 45°C. Then, 40% of PbO powder relative to the mass of the epoxy resin was added, and the bubbles were removed by vacuum mechanical stirring for 50 minutes. Subsequently, polythiols 309 was added at 1 / 3 of the mass of the epoxy resin, and vacuum stirring was continued for 30 minutes until the reaction was completed. The mixed fluid after the reaction was poured into a silicone mold, and finally placed in a vacuum drying oven. The epoxy resin was cured according to the temperature program of pre-curing at 80°C for 2 hours, curing at 110°C for 3 hours, and curing at 130°C for 4 hours. After curing, demolding was performed to obtain a PbO@epoxy resin (named UEP4-1) composite material. The experimental results show that the tensile strength of the composite material is 42.12 MPa, the bending strength is 58.63 MPa, and the shielding efficiency of UEP4-1 against 662 keV gamma rays is 1.17% (the shielding efficiency of a material with a thickness of 10 cm is calculated to be 44.56% using formula (1)). See Table 3 for details.

[0082] Comparative Example 3

[0083] This comparative example uses unmodified commercially available Bi2O3 powder with an average particle size of 500nm, bisphenol A epoxy resin E51, and polyetheramine D230 as a curing agent. The specific implementation process includes:

[0084] First, the epoxy resin E51 was placed in an oven at 80°C and heated for 30 minutes. After its viscosity decreased, the epoxy resin was weighed in a three-necked flask and heated to 45°C. Then, 40% of Bi2O3 powder relative to the mass of the epoxy resin was added, and the bubbles were removed by vacuum mechanical stirring for 50 minutes. Subsequently, 1 / 3 of the mass of the epoxy resin was added to the polyetheramine D230, and vacuum stirring was continued for 30 minutes until the reaction was completed. The mixed fluid after the reaction was poured into a silicone mold, and finally placed in a vacuum drying oven. The epoxy resin was cured according to the temperature program of 80°C pre-curing for 2 hours, 110°C curing for 3 hours, and 130°C curing for 4 hours. After curing, demolding was performed to obtain the Bi2O3@epoxy resin (named UEP4-2) composite material. The experimental results show that the tensile strength of the composite material is 52.23 MPa, the bending strength is 69.26 MPa, and the shielding efficiency of UEP4-2 against 662 keV gamma rays is 1.21% (the shielding efficiency of a material with a thickness of 10 cm is calculated to be 45.66% using formula (1)). See Table 3 for details.

[0085] Table 3

[0086]

[0087] Figure 1 and Figure 2 The contact angles of the unmodified Bi2O3 powder in comparative example 3 and the M-Bi2O3 powder modified with A171 in example 2 are shown in the figure. It can be seen that the contact angle of the unmodified Bi2O3 powder is only 6°, and the contact angle of the M-Bi2O3 modified with 2% A171 is increased to 139°, which is also the key to the long-term uniform dispersion of the modified M-Bi2O3 in the epoxy resin system. The suspension stability of the powder in the epoxy resin is greatly improved, and the complete sedimentation of the powder is increased from 2h to 18h, an increase of 9 times.

[0088] Figure 3 and Figure 4 The cross-sectional SEM-EDS images of the composite materials of Comparative Example 3 and Example 2 show that the white dots in the images represent Bi2O3 powders. The unmodified Bi2O3 powders in Comparative Example 3 have obvious agglomeration in the epoxy resin system, resulting in uneven distribution of Bi2O3 powders and greatly reduced radiation shielding performance. At the same time, the agglomeration of fillers has caused a significant decrease in the mechanical properties of the composite materials. The modified M-Bi2O3 powders are evenly distributed in the epoxy resin system, which also makes the radiation shielding performance and mechanical properties of the composite materials significantly better than those of Comparative Example 3.

[0089] Comparative Example 1 is a pure epoxy resin material without adding any filler. It can be seen that pure epoxy resin hardly shields gamma rays. After adding M-Bi2O3 as a filler, the shielding performance of EP4-2 material against gamma rays is improved by nearly 19 times.

[0090] In Comparative Example 2, a PbO@epoxy resin composite material was prepared using PbO as a filler. Although the addition of PbO improved the shielding performance of the composite material against γ rays, its mechanical properties were significantly reduced. During long-term use, it was easy to break, resulting in the leakage of toxic PbO, which was potentially harmful to humans, and the service life of the material was short. In Comparative Example 3, a Bi2O3@epoxy resin composite material was prepared using unmodified Bi2O3 as a filler. Since Bi2O3 was not modified, it was unevenly dispersed in the resin, and the mechanical properties and radiation shielding properties were worse than those of EP4-2 in Example 2 using M-Bi2O3 as a filler.

[0091] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a bismuth oxide-based epoxy resin composite material with radiation shielding function, characterized in that: The steps include: S1: using a silane coupling agent to graft-modify the surface of bismuth oxide powder to obtain surface-modified bismuth oxide powder; S2: The surface-modified bismuth oxide powder is mixed evenly with bisphenol A epoxy resin and curing agent through a mechanical blending-vacuum degassing combined process, and then poured into a mold, and a bismuth oxide-based epoxy resin composite material with radiation shielding function is prepared through a curing process.

2. The preparation method according to claim 1, characterized in that: Step S1 specifically includes the following process: S1.1: 80% to 95% anhydrous ethanol and 5% to 20% ultrapure water are mixed in a volume ratio to obtain a mixed solution, and the pH value of the mixed solution is adjusted to between 3 and 4 with 1 mol / L dilute hydrochloric acid to obtain a hydrolyzate; S1.2: Add 0.5% to 3% of silane coupling agent to the prepared hydrolyzate and stir for 20 to 60 minutes. After the silane coupling agent is completely hydrolyzed, slowly add bismuth oxide powder and ultrasonically disperse it at room temperature for 20 to 60 minutes. Transfer the suspension to a round-bottom flask, heat it to 60 to 90°C, and reflux it at a constant temperature with magnetic stirring for 3 to 6 hours. The modified product is separated by centrifugation and washed several times with an appropriate amount of anhydrous ethanol. Dry it in an oven at 60°C to constant weight to obtain the modified bismuth oxide powder.

3. The preparation method according to claim 1, characterized in that: Step S2 specifically includes the following process: The epoxy resin is placed in an oven at 80° C. and heated for 30 minutes. The dried epoxy resin is weighed into a three-necked flask and the temperature is maintained at 40-70° C., 20%-50% of the surface-modified bismuth oxide powder is added, and the bubbles are removed by vacuum mechanical stirring for 30-120 minutes. 1 / 2-1 / 5 of the curing agent is added, and the vacuum stirring is continued for 30 minutes until the reaction is completed. The mixed fluid after the reaction is poured into a silicone mold, and finally placed in a vacuum drying oven. The epoxy resin is cured according to a temperature increase program of pre-curing at 80° C. for 2 hours, curing at 110° C. for 3 hours, and curing at 130° C. for 4 hours. After curing, the mold is demolded to obtain a bismuth oxide-based epoxy resin composite material with radiation shielding function.

4. The preparation method according to claim 1, characterized in that: The particle size of the bismuth oxide powder is less than 400-800 nm.

5. The preparation method according to claim 1, characterized in that: The bisphenol A type epoxy resin includes at least one of E51, E55, E44, E42, and E35.

6. The preparation method according to claim 1, characterized in that: The silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, hexadecyltrimethoxysilane and vinyltrimethoxysilane.

7. The preparation method according to claim 1, characterized in that: The curing agent includes one or two of polyetheramine, polyamide, polythiol and fatty amine.

8. The bismuth oxide-based epoxy resin composite material having radiation shielding function obtained by the preparation method according to any one of claims 1 to 7.

9. The bismuth oxide-based epoxy resin composite material with radiation shielding function according to claim 8, characterized in that: The bismuth oxide in the composite material is uniformly dispersed; the composite material has an excellent shielding effect on 662keV gamma rays.

10. Use of the bismuth oxide-based epoxy resin composite material with radiation shielding function obtained by the preparation method according to any one of claims 1 to 7 or the bismuth oxide-based epoxy resin composite material with radiation shielding function according to claim 8 or 9.

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