Nanoprotective fibers, methods of making, applications, and protective articles

Abstract

The application provides a kind of nanometer protective fiber and its preparation method, application and protective product;Nanometer protective fiber includes core layer and shell layer, the core layer is fibrous, the shell layer is coaxially covered on the core layer, the core layer includes first polymer and neutron absorber filled in the first polymer, the shell layer includes second polymer and gamma ray shielding agent filled in the second polymer, the neutron absorber includes nanometer gadolinium oxide powder.The structure of nanometer protective fiber can simultaneously play a good protective effect on neutron and gamma ray, and the protective product prepared has good wearing comfort.

Description

Technical Field

[0001] This invention relates to the field of radiation shielding materials, and in particular to a nanofiber, its preparation method, application, and protective products. Background Technology

[0002] With the rapid development of the nuclear industry, the radiation safety and protection of nuclear power plants and reactors have become increasingly important. Currently, neutron-shielding fibers are generally produced by melt-blending boron compounds as thermal neutron absorbers with polymers such as polyethylene and polypropylene, followed by melt spinning. However, boron has a low thermal neutron capture cross-section. In wearable neutron-shielding products, achieving better neutron shielding performance requires more neutron-shielding fibers or an increased amount of boron or lithium compounds, which reduces the comfort of wearing these products.

[0003] Furthermore, protective products must not only effectively shield against neutron radiation but also against secondary gamma rays, while current commercially available protective materials or products offer only single-function radiation protection. Summary of the Invention

[0004] Therefore, it is necessary to provide a nanofiber with good wearing comfort and good neutron and gamma-ray protection, as well as its preparation method, application and protective products.

[0005] In a first aspect, the present invention provides a nanofiber for protection, comprising a core layer and a shell layer, wherein the core layer is fibrous and the shell layer is coaxially wrapped around the core layer, the core layer comprising a first polymer and a neutron absorber filled in the first polymer, and the shell layer comprising a second polymer and a gamma-ray shielding agent filled in the second polymer, wherein the neutron absorber comprises nano-gadolinium oxide powder.

[0006] This invention uses nano-gadolinium oxide powder as a neutron absorber, which can effectively improve the neutron absorption effect of nano-protective fibers. This reduces the amount of nano-protective fibers used while meeting neutron protection requirements, thus improving the comfort of wearable protective products. Simultaneously, the core-shell structure places the neutron absorber in the core layer and the gamma-ray absorber in the shell layer. This not only provides good protection against both neutrons and gamma rays in the environment, but the gamma-ray shielding agent in the shell layer further shields against secondary gamma rays generated during neutron absorption by the gadolinium powder in the core layer, preventing secondary gamma-ray problems caused by gadolinium neutron absorption and further improving the protective effect of nano-protective fibers against gamma rays and neutrons.

[0007] In some embodiments, the nanofibers satisfy at least one of the following conditions:

[0008] (1) The diameter of the core layer is 100nm-200nm;

[0009] (2) The thickness of the shell is 100nm-200nm;

[0010] (3) The diameter of the nano-protective fiber is 300nm-600nm.

[0011] In some embodiments, the nanofibers satisfy at least one of the following conditions:

[0012] (1) The particle size of the neutron absorber is 10nm-50nm;

[0013] (2) The particle size of the γ-ray shielding agent is 10nm-50nm.

[0014] In some embodiments, the gamma-ray shielding agent is selected from at least one of nano-tungsten powder, nano-tantalum powder, and nano-bismuth powder.

[0015] In some embodiments, the nanofibers satisfy at least one of the following conditions:

[0016] (1) The first polymer is selected from at least one of PVDF, TPU and PLA;

[0017] (2) The second polymer is selected from at least one of TPU and PVDF.

[0018] In a second aspect, the present invention provides a method for preparing the above-mentioned nanofibers, comprising the following steps:

[0019] Core spinning solution and shell spinning solution are added to the inner and outer cavities of a coaxial electrospinning apparatus, respectively, for electrospinning to obtain nano-protective fibers. The core spinning solution comprises a first polymer, a neutron absorber, and a first solvent, wherein the first polymer is dissolved in the first solvent and the neutron absorber is dispersed in the first solvent. The shell spinning solution comprises a second polymer, a gamma-ray shielding agent, and a second solvent, wherein the second polymer is dissolved in the second solvent and the gamma-ray shielding agent is dispersed in the second solvent.

[0020] The neutron absorber includes nano-gadolinium oxide powder.

[0021] This invention uses coaxial electrospinning to prepare nanoscale protective fibers with nanometer-scale diameters and dense stacking. These fibers not only provide excellent protection against neutrons and secondary gamma rays, but also effectively intercept α and β radioactive aerosol particles, thus offering broader protective capabilities.

[0022] In some embodiments, the preparation method satisfies at least one of the following conditions:

[0023] (1) The core spinning solution comprises, by mass percentage, 5%-20% of the first polymer, 75%-94% of the first solvent, and 1%-5% of the neutron absorber;

[0024] (2) The shell spinning solution comprises, by mass percentage, 5%-20% of the second polymer, 75%-94% of the second solvent, and 1%-5% of the γ-ray shielding agent.

[0025] In some embodiments, the preparation method satisfies at least one of the following conditions:

[0026] (1) The first solvent is selected from at least one of chloroform and N,N-dimethylformamide;

[0027] (2) The second solvent is NN-dimethylformamide.

[0028] In some embodiments, the first solvent is trichloromethane and N,N-dimethylformamide in a volume ratio of 1:(3-8).

[0029] In some embodiments, the electrospinning process parameters satisfy at least one of the following conditions:

[0030] (1) The supply rate of the core spinning solution is 0.1 mL / min-2 mL / min;

[0031] (2) The supply rate of the shell spinning solution is 0.1 mL / min-4 mL / min;

[0032] (3) Voltage is 18kV-30kV;

[0033] (4) The spinning distance is 15cm-20cm;

[0034] (5) The receiver rotation speed is 120r / min-160r / min.

[0035] In some embodiments, the ratio of the supply rate of the core spinning solution to the supply rate of the shell spinning solution is 1:(1-2).

[0036] In a third aspect, the present invention provides an application of the above-mentioned nano-protective fibers in the preparation of protective products.

[0037] In a fourth aspect, the present invention provides a protective article comprising the aforementioned nanofibers.

[0038] In some embodiments, the protective article includes fabric.

[0039] 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

[0040] Figure 1 This is a schematic diagram of a nano-protective fiber according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the coaxial electrospinning equipment used in Example 1;

[0042] Figure 3 A schematic diagram of the preparation of nanofibers using coaxial electrospinning.

[0043] Explanation of reference numerals in the attached figures:

[0044] 100-Nano protective fiber; 101-Shell layer; 102-Core layer;

[0045] 200 - Coaxial electrospinning equipment; 201 - Inner cavity; 202 - Outer cavity; 203 - Nozzle of the inner cavity; 204 - Nozzle of the outer cavity. Detailed Implementation

[0046] To facilitate understanding of the present invention, a more comprehensive description is provided below, along with preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0047] 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 invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] 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.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0050] One embodiment of the present invention provides a nano-protective fiber, which includes a core layer and a shell layer. The core layer is fibrous, and the shell layer is coaxially wrapped around the core layer. The core layer includes a first polymer and a neutron absorber filled in the first polymer. The shell layer includes a second polymer and a gamma-ray shielding agent filled in the second polymer. The neutron absorber includes nano-gadolinium oxide powder.

[0051] This invention uses nano-gadolinium oxide powder as a neutron absorber, which can effectively improve the neutron absorption effect of nano-protective fibers. This reduces the amount of nano-protective fibers used while meeting neutron protection requirements, thus improving the comfort of wearable protective products. Simultaneously, the core-shell structure places the neutron absorber in the core layer and the gamma-ray absorber in the shell layer. This not only provides good protection against both neutrons and gamma rays in the environment, but the gamma-ray shielding agent in the shell layer further shields against secondary gamma rays generated during neutron absorption by the gadolinium powder in the core layer, preventing secondary gamma-ray problems caused by gadolinium neutron absorption and further improving the protective effect of nano-protective fibers against gamma rays and neutrons.

[0052] See Figure 1 An example of a nanofiber 100 includes a core layer 101 and a shell layer 102. The core layer 101 is fibrous, and the shell layer 102 is coaxially wrapped around the core layer 101. The core layer 101 includes a first polymer and a neutron absorber filled in the first polymer. The shell layer 102 includes a second polymer and a gamma-ray shielding agent filled in the second polymer. The neutron absorber includes nano-gadolinium oxide powder.

[0053] In some embodiments, the diameter of the core layer is 100nm-200nm.

[0054] In some embodiments, the thickness of the shell layer is 100nm-200nm.

[0055] In some embodiments, the diameter of the above-mentioned nanofibers is 300nm-600nm.

[0056] Furthermore, the diameter of the aforementioned nanofibers is 300nm-400nm. The nanoscale diameter and dense stacking of these fibers not only provide excellent protection against neutrons and secondary gamma rays, but also effectively intercept alpha and beta radioactive aerosol particles, thus enabling the protective products made from them to have a wider range of protective effects.

[0057] In some embodiments, the particle size of the neutron absorber is 10 nm to 50 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm. Further, the particle size of the neutron absorber can be within the range defined by any two of the above values. Preferably, the particle size of the neutron absorber is 20 nm to 30 nm. By controlling the particle size of the neutron absorber, the compatibility and dispersion uniformity between the neutron absorber and the fiber matrix can be improved, thereby enhancing the neutron protection effect.

[0058] In some embodiments, the particle size of the gamma-ray shielding agent is 10 nm to 50 nm, for example, it can be 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm. Further, the particle size of the gamma-ray shielding agent can be within the range formed by any two of the above values. Preferably, the particle size of the gamma-ray shielding agent is 20 nm to 30 nm. By controlling the particle size of the gamma-ray shielding agent, the compatibility and dispersion uniformity between the gamma-ray shielding agent and the fiber matrix can be improved, thereby enhancing the secondary gamma-ray protection effect.

[0059] In some embodiments, the gamma-ray shielding agent may be selected from at least one of nano-tungsten powder, nano-tantalum powder, and nano-bismuth powder.

[0060] In some embodiments, the first polymer may be selected from at least one of PVDF, TPU and PLA.

[0061] In some embodiments, the first polymer is selected from PVDF. Using PVDF as the first polymer can improve the hydrophobicity of the fiber.

[0062] In some embodiments, the second polymer may be selected from at least one of TPU and PVDF.

[0063] An embodiment of the present invention provides a method for preparing the above-mentioned nano-protective fibers, comprising the following steps:

[0064] The core spinning solution and the shell spinning solution are added to the inner and outer cavities of a coaxial electrospinning apparatus, respectively, for electrospinning to obtain nano-protective fibers. The core spinning solution includes a first polymer, a neutron absorber, and a first solvent, wherein the first polymer is dissolved in the first solvent and the neutron absorber is dispersed in the first solvent. The shell spinning solution includes a second polymer, a gamma-ray shielding agent, and a second solvent, wherein the second polymer is dissolved in the second solvent and the gamma-ray shielding agent is dispersed in the second solvent.

[0065] Neutron absorbers include nano-gadolinium oxide powder.

[0066] This invention uses coaxial electrospinning to prepare nanoscale protective fibers with nanometer-scale diameters and dense stacking. These fibers not only provide excellent protection against neutrons and secondary gamma rays, but also effectively intercept α and β radioactive aerosol particles, thus offering broader protective capabilities.

[0067] In some embodiments, the preparation method of the core spinning solution includes the following steps S10-S20:

[0068] S10. Dissolve the first polymer in the first solvent to obtain the first solution;

[0069] S20. Add neutron absorber to the first solution and stir ultrasonically to obtain the core spinning solution.

[0070] By adding nanoscale neutron absorbers to a polymer solution and ultrasonically stirring to obtain a core spinning solution with a more uniform dispersion of neutron absorbers, the neutron absorbers in the nano-protective fibers prepared by coaxial electrospinning exhibit better dispersion uniformity, thereby improving the neutron protection performance of the nano-protective fibers.

[0071] In some embodiments, the preparation method of the above-mentioned shell spinning solution includes the following steps S30-S40:

[0072] S30. Dissolve the second polymer in the second solvent to obtain the second solution;

[0073] S40. Add a γ-ray shielding agent to the second solution and stir ultrasonically to obtain a shell spinning solution.

[0074] By adding a gamma-ray shielding agent to a polymer solution and ultrasonically stirring to obtain a shell spinning solution with a relatively uniform dispersion of the gamma-ray shielding agent, the gamma-ray shielding agent in the nanofiber prepared by coaxial electrospinning has better dispersion uniformity, thereby improving the gamma-ray protection performance of the nanofiber.

[0075] In some embodiments, the core spinning solution comprises, by mass percentage, 5%-20% of a first polymer, 75%-94% of a first solvent, and 1%-5% of a neutron absorber. By controlling the mass ratio between the substances in the core spinning solution, the dispersibility of the neutron absorber in the core layer can be further controlled, and the neutron protection effect can be further improved.

[0076] Furthermore, the core spinning solution described above comprises, by mass percentage, 8%-15% of the first polymer, 80%-90% of the first solvent, and 2%-5% of the neutron absorber.

[0077] In some embodiments, the concentration of the first polymer in the first solution is 5 wt% to 26.7 wt%, for example, it can be 5 wt%, 6 wt%, 8 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 20 wt%, 25 wt%, 26 wt%, or 26.7 wt%. Further, the concentration of the first polymer in the first solution can be within the range formed by any two of the above values. By controlling the concentration of the first polymer in the first solution, the diameter of the fiber core layer can be adjusted.

[0078] In some embodiments, the shell spinning solution comprises, by mass percentage, 5%-20% of a second polymer, 75%-94% of a second solvent, and 1%-5% of a gamma-ray shielding agent. By controlling the mass ratio of the substances in the shell spinning solution, the dispersibility of the gamma-ray shielding agent in the shell can be further controlled, and the gamma-ray protection effect can be further improved.

[0079] Furthermore, the shell spinning solution mentioned above, by mass percentage, includes 8%-15% of the second polymer, 80%-90% of the second solvent, and 2%-5% of the gamma-ray shielding agent.

[0080] In some embodiments, the concentration of the second polymer in the second solution is 5 wt% to 26.7 wt%, for example, it can be 5 wt%, 6 wt%, 8 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 20 wt%, 25 wt%, 26 wt%, or 26.7 wt%. Further, the concentration of the second polymer in the second solution can be within the range formed by any two of the above values. By controlling the concentration of the second polymer in the second solution, the fiber shell thickness can be adjusted.

[0081] In some embodiments, the first solvent may be selected from at least one of chloroform and N,N-dimethylformamide.

[0082] In some embodiments, the first solvent is chloroform and N:N-dimethylformamide in a volume ratio of 1:(3-8). The volume ratio of chloroform to N:N-dimethylformamide can be 1:3, 1:4, 1:5, 1:6, 1:7, or 1:8. Further, the volume ratio of chloroform to N:N-dimethylformamide can be within the range formed by any two of the above values. Preferably, the volume ratio of chloroform to N:N-dimethylformamide is 1:(3-5), resulting in better dimensional uniformity of the nanofibers obtained using the composite solvent.

[0083] In some embodiments, the second solvent may be selected from N,N-dimethylformamide.

[0084] In some embodiments, in the above electrospinning process, the core spinning solution is supplied at a rate of 0.1 mL / min to 2 mL / min.

[0085] In some embodiments, in the above electrospinning process, the supply rate of the shell spinning solution is 0.1 mL / min to 4 mL / min.

[0086] In some embodiments, the ratio of the supply rate of the core spinning solution to the supply rate of the shell spinning solution is 1:(1-2). During electrospinning, by controlling the ratio of the supply rate of the core spinning solution to the supply rate of the shell spinning solution, the core diameter and shell thickness of the nanofiber can be better controlled.

[0087] One embodiment of the present invention provides the application of the above-mentioned nano-protective fibers in the preparation of protective products.

[0088] One embodiment of the present invention provides a protective product made from the above-mentioned nano-protective fibers.

[0089] In some embodiments, the protective articles described above may be fabric or protective articles comprising fabric.

[0090] In some embodiments, the preparation method of the above-mentioned fabric includes the following steps: hot-pressing the above-mentioned nano-protective fibers with polypropylene nonwoven fabric to obtain a fabric with an inner layer containing nano-protective fibers and an outer layer containing polypropylene nonwoven fabric.

[0091] In some embodiments, the unit area mass of the polypropylene nonwoven fabric is 30 g / m². 2 -40g / m 2 .

[0092] In some embodiments, the temperature of the hot-pressing composite is 150°C-160°C.

[0093] In some embodiments, the pressure of the above-mentioned hot-pressing composite is 30Pa-40Pa.

[0094] To make the objectives, technical solutions, and advantages of this invention clearer and more concise, the invention is described using the following specific embodiments, but the invention is by no means limited to these embodiments. The embodiments described below are merely preferred embodiments of the invention and can be used to describe the invention, but should not be construed as limiting the scope of the invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0095] To better illustrate the present invention, the following embodiments are provided for further explanation. The specific embodiments are as follows.

[0096] Example 1

[0097] S1: Weigh 8g of PVDF and dissolve it in a mixed solvent of 58g of chloroform (CF) and NN-dimethylformamide (DMF), wherein the volume ratio of chloroform (CF) to NN-dimethylformamide (DMF) is 1:5. Dissolve the PVDF at 60℃ for 24h with a magnetic stirrer until the PVDF is completely dissolved to obtain a PVDF solution with a mass fraction of 12wt%. Add 1g of 20nm gadolinium oxide nanoparticles to the PVDF solution and stir ultrasonically until the mixture is uniform to obtain the core spinning solution.

[0098] S2: Weigh 16g of TPU and dissolve it in 117g of NN-dimethylformamide (DMF) solution. Dissolve the TPU at 60℃ for 24h using a magnetic stirrer. After the TPU is completely dissolved, a TPU solution is obtained. Add 1.6g of 30nm nano-tungsten powder to the TPU solution and stir ultrasonically until the mixture is uniform to obtain a shell spinning solution.

[0099] S3: The core spinning solution and the shell spinning solution are added to the inner and outer cavities of the coaxial electrospinning equipment for electrospinning to obtain a nanofiber membrane with a core and shell structure. The spinning process parameters are: voltage 18kV, spinning distance 15cm, receiver rotation speed 120r / min, and the supply rate of the shell spinning solution is 0.5ml / min and 1ml / min.

[0100] See Figure 2 and Figure 3In the coaxial electrospinning equipment, the inner cavity 201 is connected to the nozzle 203 of the inner cavity. The core layer spinning solution is added to the inner cavity and can be sprayed out from the nozzle of the inner cavity. The outer cavity 202 of the coaxial electrospinning equipment is connected to the nozzle 204 of the outer cavity. The shell layer spinning solution is added to the outer cavity and can be sprayed out from the nozzle of the outer cavity. The nozzle 201 of the inner cavity is inside the nozzle 204 of the outer cavity. When preparing nano-protective fibers, the core layer spinning solution and the shell layer spinning solution are sprayed out simultaneously from the nozzle of the inner cavity and the nozzle of the outer cavity, respectively, to form nano-protective fibers with core layer and shell layer structures. The sprayed nano-protective fibers form a nano-protective fiber film on the receiving substrate.

[0101] The preparation methods of Examples 2-3 are basically the same as those of Example 1, except that the first solvent of Example 2 is a mixed solvent composed of CF and DMF with a volume ratio of 1:3, and the first solvent of Example 3 is a mixed solvent composed of CF and DMF with a volume ratio of 1:8. The other raw material components, addition amounts and process parameters are the same as those of Example 1.

[0102] The preparation methods of Examples 4-6 are basically the same as those of Example 1, except that the particle size of the nano-gadolinium oxide used is different. Example 4 uses nano-gadolinium oxide powder with a particle size of 10 nm, Example 5 uses nano-gadolinium oxide powder with a particle size of 30 nm, and Example 6 uses nano-gadolinium oxide powder with a particle size of 50 nm. The other raw material components, addition amounts and process parameters are the same as those of Example 1.

[0103] The preparation methods of Examples 7-9 are basically the same as those of Example 1, except that the particle size of the γ-ray shielding agent used is different. Example 7 uses tungsten powder with a particle size of 10 nm, Example 8 uses tungsten powder with a particle size of 20 nm, and Example 9 uses tungsten powder with a particle size of 50 nm. The other raw material components, addition amounts and process parameters are the same as those of Example 1.

[0104] The preparation methods of Examples 10-13 are basically the same as those of Example 1, except that the raw material formulations are different, as detailed in Table 1.

[0105] Comparative Example 1

[0106] The preparation methods of Comparative Example 1 and Example 1 are basically the same, except that the neutron shielding agent in Comparative Example 1 uses 20nm boron carbide instead of nano gadolinium oxide powder in Example 1.

[0107] Comparative Example 2

[0108] The raw materials and proportions used in this comparative example are the same as those in Example 1. The difference is that in Comparative Example 2, the core layer solution and the shell layer solution are mixed first, and then the mixture is added to the electrospinning equipment. The nozzle diameter of the electrospinning equipment is controlled to obtain nano-protective fibers with the same diameter as the nano-protective fibers prepared in Example 1.

[0109] Comparative Example 3

[0110] The raw materials and proportions used in this comparative example are the same as those in Example 1. The only difference is that in Comparative Example 3, the core spinning solution is added to the outer cavity of the coaxial electrospinning equipment, and the shell spinning solution is added to the inner cavity of the coaxial electrospinning equipment, to obtain a nano-protective fiber with a core containing a γ-ray shielding agent and a shell containing a neutron absorber.

[0111] The raw material formulations for Examples 1-16 and Comparative Examples 1-6 are shown in Table 1:

[0112] Table 1

[0113]

[0114]

[0115] Table 2 shows the mass percentage of each component in the core spinning solution and shell spinning solution during the preparation of nanofibers in Examples 1, 12-15.

[0116] Table 2

[0117]

[0118]

[0119] Performance testing

[0120] The above-mentioned nano-protective fiber membrane is hot-pressed and laminated with polypropylene nonwoven fabric to obtain a fabric with an inner layer of nano-protective fiber membrane and an outer layer of polypropylene nonwoven fabric. The thickness of the nano-fiber membrane is 1 mm and the thickness of the fabric is 3 mm.

[0121] Thermal neutron shielding performance test method

[0122] Tests were conducted using a neutron dose equivalent rate standard device, measuring the count rate of the thermal neutron detector with and without the sample being tested for shielding. The position and orientation of the thermal neutron detector remained constant throughout the measurement process, and the plane of the sample was parallel to the thermal neutron emission plane of the moderator. The thermal neutron shielding performance of the sample was determined by comparing the count rate results under the two conditions.

[0123] To prevent neutrons from other directions from affecting the test results, the thermal neutron detector was placed in a cubic cadmium shielded box made of cadmium sheets with a thickness of 2 mm. The side of the cadmium shield facing the moderator's thermal neutron emission plane had no shielding plate, ensuring that the thermal neutron detector only received thermal neutrons from the moderator's direction. The specific experimental steps are as follows:

[0124] (1) Place the cadmium shielding box and detector in the center of the test area and measure the detector count rate when there is no sample.

[0125] (2) Keep the positions of the cadmium shielding box and the detector unchanged, place the sample to be tested on the surface of the cadmium shielding box facing the thermal neutron emission plane of the moderator, and measure the count rate of the detector when there is a sample.

[0126] (3) The thermal neutron shielding performance of the sample is calculated using the following formula.

[0127]

[0128] Where η represents the shielding performance, and C s C represents the count rate after adding shielding material. b This represents the count rate when the cadmium box has no sample.

[0129] The fiber diameter was tested by direct observation using a scanning electron microscope.

[0130] Filtration efficiency test method: The test shall be conducted in accordance with GB / T 29511-2013 Protective Clothing Solid Particulate Chemical Protective Clothing, Appendix B.

[0131] Test method for gamma-ray protection efficiency: Refer to GBZ / T 147-2002 Determination of attenuation performance of X-ray protective materials, and test the protection efficiency of the fabric against gamma rays in the 130keV energy range.

[0132] The performance test structures of the nano-protective fibers and fabrics made from them in Examples 1-15 and Comparative Examples 1-3 are shown in Table 3:

[0133] Table 3

[0134]

[0135] As can be seen from the performance test data in Table 3, when nano-gadolinium oxide is used as the neutron absorber in Example 1, the nano-protective fiber prepared in Example 1 has a better shielding effect on thermal neutrons compared to boron carbide used as the neutron absorber in Comparative Example 1.

[0136] Comparative Example 2 involved mixing the core layer solution and the shell layer solution to obtain a nanofiber containing both a neutron absorber and a gamma-ray shielding agent, but it was not a core layer structure. Comparative Example 3 prepared a nanofiber with a gamma-ray shielding agent in the core layer and a neutron absorber in the shell layer. The results showed that the nanofibers prepared in Comparative Examples 2-3 were less effective at protecting against thermal neutrons and gamma rays than those in Example 1. The reason why the nanofibers prepared in Comparative Examples 2-3 were less effective at protecting against gamma rays than those in Example 1 is that the nanofibers prepared in Example 1 placed the neutron absorber in the core layer, and the surface of the core layer was covered with a shell layer containing a gamma-ray shielding agent. When exposed to neutron radiation, the neutron rays were absorbed by the gadolinium in the core layer, making it difficult for them to penetrate the fiber. Simultaneously, the secondary gamma rays generated by the gadolinium absorbing neutrons in the core layer could be blocked by the gamma-ray shielding agent in the shell layer, preventing the secondary gamma rays from penetrating the fiber. When exposed to gamma-ray radiation, the gamma rays were blocked by the gamma-ray shielding agent in the shell layer, making it difficult for the gamma rays to penetrate the fiber, thus achieving the effect of simultaneously protecting against neutrons and gamma rays. While the nano-protective fibers in Comparative Examples 2-3 can provide protection against neutrons and gamma rays in the environment, the secondary gamma rays generated by the gadolinium neutron absorber when absorbing neutrons can penetrate the fibers through gaps where there is no gamma ray shielding agent. This means that the fiber fabric cannot effectively shield against secondary gamma rays, thus reducing the fabric's protective effect against gamma rays.

[0137] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0138] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A nanofiber for protection, characterized in that, The device comprises a core layer and a shell layer obtained by coaxial electrospinning. The core layer is fibrous, and the shell layer coaxially coats the core layer. The core layer includes a first polymer and a neutron absorber filled in the first polymer. The shell layer includes a second polymer and a gamma-ray shielding agent filled in the second polymer. The first polymer is selected from at least one of PVDF, TPU, and PLA. The second polymer is selected from at least one of TPU and PVDF. The gamma-ray shielding agent is selected from at least one of nano-tungsten powder, nano-tantalum powder, and nano-bismuth powder. The neutron absorber is nano-gadolinium oxide powder. The diameter of the nano-protective fibers is 300nm-600nm. The particle size of the neutron absorber is 20nm-30nm. The particle size of the gamma-ray shielding agent is 20nm-30nm.

2. The nanofiber as described in claim 1, characterized in that, The nanofibers meet at least one of the following conditions: (1) The diameter of the core layer is 100nm-200nm; (2) The thickness of the shell is 100nm-200nm; (3) The diameter of the nano-protective fiber is 300nm-400nm.

3. The method for preparing the nanoprotective fiber according to any one of claims 1-2, characterized in that, Includes the following steps: Core spinning solution and shell spinning solution are added to the inner and outer cavities of a coaxial electrospinning apparatus, respectively, for electrospinning to obtain nano-protective fibers. The core spinning solution comprises a first polymer, a neutron absorber, and a first solvent, wherein the first polymer is dissolved in the first solvent and the neutron absorber is dispersed in the first solvent. The shell spinning solution comprises a second polymer, a gamma-ray shielding agent, and a second solvent, wherein the second polymer is dissolved in the second solvent and the gamma-ray shielding agent is dispersed in the second solvent. The neutron absorber is nano-gadolinium oxide powder.

4. The preparation method according to claim 3, characterized in that, The preparation method satisfies at least one of the following conditions: (1) The core spinning solution comprises, by mass percentage, 5%-20% of the first polymer, 75%-94% of the first solvent, and 1%-5% of the neutron absorber; (2) The shell spinning solution contains, by mass percentage, 5%-20% of the second polymer, 75%-94% of the second solvent and 1%-5% of the γ-ray shielding agent.

5. The preparation method according to any one of claims 3-4, characterized in that, The preparation method satisfies at least one of the following conditions: (1) The first solvent is selected from at least one of chloroform and N,N-dimethylformamide; (2) The second solvent is N,N-dimethylformamide.

6. The preparation method according to claim 5, characterized in that, The first solvent is chloroform and N,N-dimethylformamide in a volume ratio of 1:3 to 1:

8.

7. The preparation method according to any one of claims 3-4, characterized in that, The electrospinning process parameters satisfy at least one of the following conditions: (1) The supply rate of the core spinning solution is 0.1 mL / min to 2 mL / min; (2) The supply rate of the shell spinning solution is 0.1 mL / min-4 mL / min; (3) The voltage of the electrospinning is 18kV-30kV; (4) The spinning distance of the electrospinning is 15cm-20cm; (5) The receiver rotation speed of the electrospinning is 120r / min-160r / min.

8. The preparation method according to claim 7, characterized in that, The ratio of the supply rate of the core spinning solution to the supply rate of the shell spinning solution is 1:1 to 1:

2.

9. The use of the nanofibers as described in any one of claims 1-2 in the preparation of protective articles.

10. A protective product, characterized in that, The protective product includes the nanofibers described in any one of claims 1-2.

11. The protective article as described in claim 10, characterized in that, The protective products include fabrics.

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