NANO protective fiber and preparation method therefor and use thereof, and protective product thereof

Abstract

The invention provides a nano protective fiber and a preparation method therefor and the use thereof, and a protective product thereof. The nano protective fiber comprises a core layer and a shell layer, wherein the core layer is fibrous, and the shell layer is coaxially coated on the core layer; the core layer comprises a first polymer and a neutron absorber filled in the first polymer, and the shell layer comprises a second polymer and a γ-ray shielding agent filled in the second polymer; and the neutron absorber comprises nano gadolinium oxide powder. Nano protective fiber having such a structure can achieve a good protective effect on both neutrons and γ-rays, and a protective product prepared therefrom is very comfortable to wear.

Description

Nano protective fiber and its preparation method, application and protective product

[0001] Related applications

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on November 22, 2023, with application number 2023115654642, entitled “Nano protective fibers, their preparation methods, applications and protective products”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of radiation shielding materials, and in particular to a nano protective fiber and its preparation method, application and protective product. Background Art

[0004] With the rapid development of the nuclear industry, radiation safety and protection issues in nuclear power plants and nuclear reactors are becoming increasingly important. Currently, neutron-shielding fibers are typically produced by melt-blending boron compounds as thermal neutron absorbers with polymers such as polyethylene and polypropylene, and then using a melt-spinning method to produce neutron-shielding protective fibers. However, boron has a low thermal neutron capture cross-section. To achieve better neutron shielding performance in wearable neutron-shielding products, more neutron-shielding fibers are required, or the amount of boron or lithium compounds added to the fibers must be increased, which in turn reduces the wearer's comfort.

[0005] Furthermore, protective products need to provide effective shielding against neutron radiation as well as secondary gamma rays, but current commercial protective materials or products have only a single radiation protection function.

[0006] Summary of the Invention

[0007] Based on this, it is necessary to provide a nano protective fiber with good wearing comfort, better neutron and gamma ray protection effect, and its preparation method, application and protective product.

[0008] In a first aspect of the present application, a nano-protective fiber is provided, comprising a core layer and a shell layer, wherein the core layer is fibrous, the shell layer is coaxially coated on the core layer, the core layer comprises a first polymer and a neutron absorber filled in the first polymer, the shell layer comprises a second polymer and a gamma-ray shielding agent filled in the second polymer, and the neutron absorber comprises nano-gadolinium oxide powder.

[0009] The present application uses nano-gadolinium oxide powder as a neutron absorber, which can effectively improve the absorption effect of nano-protective fibers on neutrons, thereby reducing the use of nano-protective fibers while meeting the neutron protection requirements and improving the comfort of wearable protective products; at the same time, a core layer and shell layer structure is adopted, and the neutron absorber is placed in the core layer and the gamma-ray absorber is placed in the shell layer, which not only has a good protection effect on neutrons and gamma rays in the environment, but the gamma-ray shielding agent in the shell layer can further shield the secondary gamma rays brought about by the nano-gadolinium oxide powder in the core layer absorbing neutrons, reducing or preventing the secondary gamma ray problem caused by the nano-gadolinium oxide absorbing neutrons, and further improving the protection effect of the nano-protective fibers against gamma rays and neutrons.

[0010] In some embodiments, the nano protective fiber satisfies at least one of the following conditions:

[0011] (1) The diameter of the core layer is 100 nm to 200 nm;

[0012] (2) The thickness of the shell layer is 100 nm to 200 nm;

[0013] (3) The diameter of the nano protective fiber is 300nm-600nm.

[0014] In some embodiments, the nano protective fiber satisfies at least one of the following conditions:

[0015] (1) The particle size of the neutron absorber is 10 nm to 50 nm;

[0016] (2) The particle size of the gamma-ray shielding agent is 10 nm to 50 nm.

[0017] 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.

[0018] In some embodiments, the nano protective fiber satisfies at least one of the following conditions:

[0019] (1) the first polymer is selected from at least one of PVDF, TPU and PLA;

[0020] (2) The second polymer is selected from at least one of TPU and PVDF.

[0021] In a second aspect, the present application provides a method for preparing the aforementioned nano protective fiber, comprising the following steps:

[0022] adding a core layer spinning solution and a shell layer spinning solution to the inner cavity and outer cavity of a coaxial electrospinning device, respectively, and performing electrospinning to obtain a nano protective fiber; the core layer spinning solution comprises a first polymer, a neutron absorber, and a first solvent, the first polymer is dissolved in the first solvent, and the neutron absorber is dispersed in the first solvent; the shell layer spinning solution comprises a second polymer, a gamma-ray shielding agent, and a second solvent, the second polymer is dissolved in the second solvent, and the gamma-ray shielding agent is dispersed in the second solvent;

[0023] The neutron absorber includes nano-gadolinium oxide powder.

[0024] The present application adopts the coaxial electrospinning method to prepare nano-scale protective fibers. The diameter of the fibers is at the nanometer level and they are densely stacked. They not only have a good protective effect against neutrons and secondary gamma rays, but also have a good interception effect against α and β radioactive aerosol particles, thus having a wider range of protective effects.

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

[0026] (1) In the core layer spinning solution, the first polymer comprises 5% to 20%, the first solvent comprises 75% to 94% and the neutron absorber comprises 1% to 5% by weight;

[0027] (2) The shell spinning solution comprises, by weight percentage, 5%-20% of the second polymer, 75%-94% of the second solvent, and 1%-5% of the gamma-ray shielding agent.

[0028] In some embodiments, the preparation method satisfies at least one of the following conditions:

[0029] (1) the first solvent is selected from at least one of chloroform and NN-dimethylformamide;

[0030] (2) The second solvent is NN-dimethylformamide.

[0031] In some embodiments, the first solvent is chloroform and NN-dimethylformamide in a volume ratio of 1:(3-8).

[0032] In some embodiments, the electrospinning process parameters satisfy at least one of the following conditions:

[0033] (1) The supply rate of the core layer spinning solution is 0.1 mL / min-2 mL / min;

[0034] (2) The shell spinning solution is supplied at a rate of 0.1 mL / min to 4 mL / min;

[0035] (3) Voltage is 18kV-30kV;

[0036] (4) Spinning distance is 15cm-20cm;

[0037] (5) The receiver speed is 120r / min-160r / min.

[0038] In some embodiments, the ratio of the liquid supply speed of the core layer spinning solution to the liquid supply speed of the shell layer spinning solution is 1:(1-2).

[0039] In a third aspect, the present application provides an application of the above-mentioned nano protective fiber in the preparation of protective products.

[0040] In a fourth aspect, the present application provides a protective product comprising the above-mentioned nano protective fiber.

[0041] In some embodiments, the protective article comprises a fabric comprising the nano protective fiber according to any one of claims 1 to 5.

[0042] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0044] FIG1 is a schematic diagram of a nano protective fiber according to an embodiment of the present application;

[0045] FIG2 is a schematic diagram of the coaxial electrospinning apparatus used in Example 1;

[0046] Figure 3 is a schematic diagram of the preparation of nano protective fibers by coaxial electrospinning.

[0047] Description of reference numerals:

[0048] 100-nanometer protective fiber; 101-shell layer; 102-core layer;

[0049] 200 - coaxial electrospinning device; 201 - inner cavity; 202 - outer cavity; 203 - nozzle of the inner cavity; 204 - nozzle of the outer cavity. DETAILED DESCRIPTION

[0050] To facilitate understanding of the present application, the present application will be described in more detail below, along with preferred embodiments thereof. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that these embodiments are provided for the purpose of providing a more thorough and comprehensive understanding of the disclosure of the present application.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are intended only to describe specific embodiments and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0053] 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0054] One embodiment of the present application 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 coated on 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.

[0055] The present application uses nano-gadolinium oxide powder as a neutron absorber, which can effectively improve the absorption effect of nano-protective fibers on neutrons, thereby reducing the use of nano-protective fibers while meeting the neutron protection requirements and improving the comfort of wearable protective products; at the same time, a core layer and shell layer structure is adopted, and the neutron absorber is placed in the core layer and the gamma-ray absorber is placed in the shell layer, which not only has a good protection effect on neutrons and gamma rays in the environment, but the gamma-ray shielding agent in the shell layer can further shield the secondary gamma rays brought about by the nano-gadolinium oxide powder in the core layer absorbing neutrons, reducing or preventing the secondary gamma ray problem caused by the nano-gadolinium oxide absorbing neutrons, and further improving the protection effect of the nano-protective fibers against gamma rays and neutrons.

[0056] Referring to Figure 1, an example of a nano-protective fiber 100 includes a core layer 101 and a shell layer 102. The core layer 101 is fibrous, and the shell layer 102 is coaxially coated on 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.

[0057] In some embodiments, the diameter of the core layer is 100 nm-200 nm.

[0058] In some embodiments, the shell layer has a thickness of 100 nm to 200 nm.

[0059] In some embodiments, the diameter of the nano protective fibers is 300 nm-600 nm.

[0060] Furthermore, the nano-protective fibers have a diameter of 300nm-400nm. These nano-sized fibers are densely packed and offer excellent protection not only against neutrons and secondary gamma rays, but also against alpha and beta radioactive aerosol particles, thus enabling protective products made from them to offer a wider range of protection.

[0061] In some embodiments, the particle size of the neutron absorber is between 10 nm and 50 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm. Furthermore, the particle size of the neutron absorber can be within a range consisting of any two of the aforementioned values. Preferably, the particle size of the neutron absorber is between 20 nm and 30 nm. By controlling the particle size of the neutron absorber, the compatibility and uniformity of the neutron absorber with the fiber matrix can be improved, thereby enhancing the neutron protection effect.

[0062] In some embodiments, the particle size of the gamma-ray shielding agent is between 10 nm and 50 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm. Furthermore, the particle size of the gamma-ray shielding agent can be within a range defined by any two of the aforementioned values. Preferably, the particle size of the gamma-ray shielding agent is between 20 nm and 30 nm. By controlling the particle size of the gamma-ray shielding agent, the compatibility and uniformity of the gamma-ray shielding agent with the fiber matrix can be improved, thereby enhancing the secondary gamma-ray protection effect.

[0063] 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.

[0064] In some embodiments, the first polymer may be selected from at least one of polyvinylidene fluoride (PVDF), thermoplastic polyurethane elastomer rubber (TPU), and polylactic acid (PLA).

[0065] In some embodiments, the first polymer is polyvinylidene fluoride (PVDF). Using PVDF as the first polymer can improve the hydrophobicity of the fiber.

[0066] In some embodiments, the second polymer may be selected from at least one of thermoplastic polyurethane elastomer rubber (TPU) and polyvinylidene fluoride (PVDF).

[0067] One embodiment of the present application provides a method for preparing the aforementioned nano protective fiber, comprising the following steps:

[0068] The core layer spinning solution and the shell layer spinning solution are respectively added to the inner cavity and the outer cavity of the coaxial electrospinning device to perform electrospinning to obtain the nano protective fiber; the core layer spinning solution includes a first polymer, a neutron absorber and a first solvent, the first polymer is dissolved in the first solvent, and the neutron absorber is dispersed in the first solvent; the shell layer spinning solution includes a second polymer, a gamma ray shielding agent and a second solvent, the second polymer is dissolved in the second solvent, and the gamma ray shielding agent is dispersed in the second solvent;

[0069] The neutron absorber includes nano-gadolinium oxide powder.

[0070] The present application adopts the coaxial electrospinning method to prepare nano-level protective fibers. The diameter of the fibers is at the nanometer level and they are densely stacked. They not only have a good protective effect against neutrons and secondary gamma rays, but also have a good interception effect against α and β radioactive aerosol particles, thus having a wider range of protective effects.

[0071] In some embodiments, the method for preparing the core layer spinning solution includes the following steps S10-S20:

[0072] S10, dissolving the first polymer in a first solvent to obtain a first solution;

[0073] S20, adding a neutron absorber to the first solution, and ultrasonically stirring to obtain a core layer spinning solution.

[0074] By adding nano-scale neutron absorbers to a polymer solution and ultrasonically stirring it, a core spinning solution in which the neutron absorber is more evenly dispersed is obtained. The neutron absorber in the nano-protective fiber prepared by coaxial electrospinning has better dispersion uniformity, thereby improving the neutron protection performance of the nano-protective fiber.

[0075] In some embodiments, the method for preparing the shell spinning solution includes the following steps S30-S40:

[0076] S30, dissolving the second polymer in a second solvent to obtain a second solution;

[0077] S40, adding a gamma-ray shielding agent to the second solution, and ultrasonically stirring to obtain a shell spinning solution.

[0078] By adding a gamma-ray shielding agent to a polymer solution and ultrasonically stirring it, a shell spinning solution in which the gamma-ray shielding agent is more evenly dispersed is obtained. The gamma-ray shielding agent in the nano-protective fiber prepared by coaxial electrospinning has better dispersion uniformity, thereby improving the gamma-ray protection performance of the nano-protective fiber.

[0079] In some embodiments, the core layer spinning solution comprises, by weight, 5%-20% of the first polymer, 75%-94% of the first solvent, and 1%-5% of the neutron absorber. By controlling the mass ratios of the various substances in the core layer spinning solution, the dispersion of the neutron absorber in the core layer can be further controlled, thereby further improving the neutron protection effect.

[0080] Furthermore, the core layer spinning solution comprises, by weight percentage, 8%-15% of the first polymer, 80%-90% of the first solvent, and 2%-5% of the neutron absorber.

[0081] In some embodiments, the concentration of the first polymer in the first solution is 5 wt% to 26.7 wt%, for example, 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%. Furthermore, the concentration of the first polymer in the first solution can be within a range defined by any two of the aforementioned values. By controlling the concentration of the first polymer in the first solution, the diameter of the fiber core layer can be controlled.

[0082] In some embodiments, the shell spinning solution comprises, by weight, 5%-20% of the second polymer, 75%-94% of the second solvent, and 1%-5% of the gamma-ray shielding agent. By controlling the mass ratio of the various substances in the shell spinning solution, the dispersibility of the gamma-ray shielding agent in the shell can be further controlled, thereby further improving the gamma-ray protection effect.

[0083] Furthermore, the shell spinning solution comprises, by weight percentage, 8%-15% of the second polymer, 80%-90% of the second solvent, and 2%-5% of the gamma-ray shielding agent.

[0084] In some embodiments, the concentration of the second polymer in the second solution is 5 wt% to 26.7 wt%, for example, 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%. Furthermore, the concentration of the second polymer in the second solution can be within a range defined by any two of the aforementioned values. By controlling the concentration of the second polymer in the second solution, the fiber shell thickness can be controlled.

[0085] In some embodiments, the first solvent may be selected from at least one of chloroform and NN-dimethylformamide.

[0086] In some embodiments, the first solvent is chloroform and NN-dimethylformamide in a volume ratio of 1:(3-8). The volume ratio of chloroform and NN-dimethylformamide can be 1:3, 1:4, 1:5, 1:6, 1:7, or 1:8. Furthermore, the volume ratio of chloroform and NN-dimethylformamide can be within a range consisting of any two of the above values. Preferably, the volume ratio of chloroform and NN-dimethylformamide is 1:(3-5). The nano-protective fibers obtained using the composite solvent have better dimensional uniformity.

[0087] In some embodiments, the second solvent may be NN-dimethylformamide.

[0088] In some embodiments, in the electrospinning process, the supply rate of the core layer spinning solution is 0.1 mL / min-2 mL / min.

[0089] In some embodiments, in the above electrospinning process, the shell spinning solution is supplied at a rate of 0.1 mL / min to 4 mL / min.

[0090] In some embodiments, the ratio of the core layer spinning solution feed rate to the shell layer spinning solution feed rate is 1:(1-2). During the electrospinning process, by controlling the ratio of the core layer spinning solution feed rate to the shell layer spinning solution feed rate, the core layer diameter and shell layer thickness of the nano-protective fiber can be better controlled.

[0091] One embodiment of the present application provides an application of the above-mentioned nano-protective protective fiber in the preparation of protective products.

[0092] One embodiment of the present application provides a protective product prepared using the above-mentioned nano protective fibers.

[0093] In some embodiments, the protective article may be a fabric, or a protective article comprising a fabric, wherein the fabric comprises the nano protective fiber.

[0094] In some embodiments, the preparation method of the above-mentioned fabric includes the following steps: hot-pressing and compounding the above-mentioned nano protective fiber and polypropylene non-woven fabric to obtain a fabric whose inner layer contains nano protective fiber and whose outer layer contains polypropylene non-woven fabric.

[0095] In some embodiments, the unit area mass of the polypropylene non-woven fabric is 30 g / m 2 -40g / m 2 .

[0096] In some embodiments, the temperature of the hot pressing lamination is 150°C-160°C.

[0097] In some embodiments, the pressure of the hot pressing compound is 30Pa-40Pa.

[0098] In order to make the purpose, technical solutions and advantages of this application more concise and clear, this application is illustrated with the following specific examples, but this application is by no means limited to these examples. The embodiments described below are only preferred embodiments of this application and can be used to describe this application. They should not be understood as limiting the scope of this application. It should be pointed out that any modifications, equivalent replacements and improvements made within the spirit and principles of this application should be included in the scope of protection of this application.

[0099] In order to better illustrate the present application, the present application is further described below in conjunction with the embodiments. The following are specific embodiments.

[0100] Example 1

[0101] S1: 8 g of PVDF was weighed and dissolved in 58 g of a mixed solvent of chloroform (CF) and NN-dimethylformamide (DMF), wherein the volume ratio of chloroform (CF) to NN-dimethylformamide (DMF) was 1:5. The mixture was dissolved at 60°C using a magnetic stirrer for 24 h. After the PVDF was completely dissolved, a PVDF solution with a mass fraction of 12.12 wt% was obtained. 1 g of nano-gadolinium oxide powder with a particle size of 20 nm was added to the PVDF solution, and ultrasonic stirring was performed until the mixture was uniformly mixed to obtain a core layer spinning solution.

[0102] S2: Weigh 16 g of TPU and dissolve it in 117 g of N-N-dimethylformamide (DMF) solution. Dissolve it at 60°C using a magnetic stirrer for 24 hours. After the TPU is completely dissolved, a TPU solution is obtained. Add 1.6 g of nano-tungsten powder with a particle size of 30 nm to the TPU solution, and ultrasonically stir until the mixture is uniform to obtain a shell spinning solution.

[0103] S3: The core layer spinning solution and the layer spinning solution were added to the inner and outer cavities of the coaxial electrospinning apparatus and electrospun to produce a nano-protective fiber membrane with a core layer and shell layer structure. The spinning process parameters were: voltage 18 kV, spinning distance 15 cm, receiver speed 120 rpm, shell layer spinning solution feed rate 0.5 ml / min, and shell layer spinning solution feed rate 1 ml / min.

[0104] Referring to Figures 2 and 3, the inner cavity 201 in the coaxial electrospinning device is connected to the inner cavity nozzle 203, and the core layer spinning solution is added in the inner cavity and can be sprayed out from the inner cavity nozzle; the outer cavity 202 in the coaxial electrospinning device is connected to the outer cavity nozzle 204, and the shell layer spinning solution is added in the outer cavity and can be sprayed out from the outer cavity nozzle. The inner cavity nozzle 201 is inside the outer cavity nozzle 204. When preparing nano protective fibers, the core layer spinning solution and the shell layer spinning solution are respectively sprayed out from the inner cavity nozzle and the outer cavity nozzle at the same time to form a nano protective fiber with a core layer and a shell layer structure. The sprayed nano protective fiber forms a nano protective fiber membrane on the receiving substrate.

[0105] The preparation method of Example 2-3 is basically the same as that of Example 1, except that the first solvent of Example 2 is a mixed solvent consisting of CF and DMF with a volume ratio of 1:3, and the first solvent of Example 3 is a mixed solvent consisting 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.

[0106] The preparation methods of Examples 4-6 are basically the same as those of Example 1, with the only difference being that the particle sizes of the nano-gadolinia used are different. Example 4 uses nano-gadolinia powder with a particle size of 10 nm, Example 5 uses nano-gadolinia powder with a particle size of 30 nm, and Example 6 uses nano-gadolinia 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.

[0107] The preparation methods of Examples 7-9 are basically the same as those of Example 1, with the only difference being 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.

[0108] The preparation methods of Examples 10-13 are basically the same as those of Example 1, except that the raw material formulas are different. See Table 1 for details.

[0109] Comparative Example 1

[0110] The preparation methods of Comparative Example 1 are basically the same as those of Example 1, with the only difference being that the neutron shielding agent of Comparative Example 1 uses 20 nm boron carbide instead of the nano-gadolinium oxide powder in Example 1.

[0111] Comparative Example 2

[0112] The raw materials and proportions used in this comparative example are consistent with those in Example 1. The difference is that, in Comparative Example 2, the core layer solution and the shell layer solution are first mixed, and then the mixed solution is added to the electrospinning equipment, and the nozzle aperture of the electrospinning equipment is controlled to obtain a nano protective fiber with a diameter consistent with that of the nano protective fiber prepared in Example 1.

[0113] Comparative Example 3

[0114] The raw materials and proportions used in this comparative example are consistent with those in Example 1, with the only difference being that, in Comparative Example 3, the core layer spinning solution is added to the outer cavity of the coaxial electrospinning device, and the shell layer spinning solution is added to the inner cavity of the coaxial electrospinning device, thereby obtaining a nano-protective fiber in which the core layer contains a γ-ray shielding agent and the shell layer contains a neutron absorber.

[0115] The raw material formulas of Examples 1-13 and Comparative Examples 1-3 are shown in Table 1:

[0116] Table 1

[0117] Table 2 shows the mass percentages of the components in the core layer spinning solution and the shell layer spinning solution when preparing the nano protective fibers in Examples 1 and 10 to 13.

[0118] Table 2

[0119] Performance Testing

[0120] The above-mentioned nano protective fiber membrane and polypropylene non-woven fabric are hot-pressed and composited to obtain a fabric with an inner layer of nano protective fiber membrane and an outer layer of polypropylene non-woven 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 thermal neutron detector count rate with and without shielding from the sample under test. The position and orientation of the thermal neutron detector remained constant during the measurement, and the plane of the sample under test was parallel to the thermal neutron emission plane of the moderator. The thermal neutron shielding performance of the sample under test 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 is placed in a cubic cadmium shielding box surrounded by 2mm thick cadmium sheets. There is no spacer on the side of the cadmium shielding box facing the thermal neutron emission plane of the moderator, ensuring that the thermal neutron detector only receives thermal neutrons from the moderator. 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) Keeping the positions of the cadmium shielding box and the detector unchanged, place the sample to be measured on the surface of the cadmium shielding box facing the thermal neutron emission plane of the moderator, and measure the counting rate of the detector when the sample is present;

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

[0127] Among them, η is the shielding performance, C s is the counting rate after adding shielding material; C b is the counting rate when there is no sample in the cadmium box.

[0128] Testing method for fiber diameter: direct observation using a scanning electron microscope.

[0129] Filtration efficiency test method: Test according to GB / T 29511-2013 Protective clothing - Chemical protective clothing for solid particles, Appendix B.

[0130] Gamma ray protection efficiency test method: Refer to "GBZ / T 147-2002 Determination of attenuation properties of X-ray protection materials" to test the protection efficiency of fabrics against gamma rays in the 130keV energy range.

[0131] The performance test structures of the nano protective fibers and the fabrics made therefrom of Examples 1-13 and Comparative Examples 1-3 are shown in Table 3:

[0132] Table 3

[0133] From the performance test data in Table 3, it can be seen that when Example 1 uses nano-gadolinium oxide as a neutron absorber, the nano-protective fiber prepared in Example 1 has a better shielding effect against thermal neutrons than when Comparative Example 1 uses boron carbide as a neutron absorber.

[0134] In Comparative Example 2, the core layer solution and the shell layer solution were first mixed to obtain a nano-protective fiber containing both a neutron absorber and a gamma-ray shielding agent, but this fiber did not have a core layer structure. Comparative Example 3 prepared a nano-protective fiber with a core layer containing a gamma-ray shielding agent and a shell layer containing a neutron absorber. The results showed that the nano-protective fibers prepared in Comparative Examples 2-3 were less effective against both thermal neutrons and gamma-rays than those in Example 1. The nano-protective fibers prepared in Comparative Examples 2-3 were less effective against gamma-rays than those in Example 1 because the nano-protective fibers prepared in Example 1 placed the neutron absorber in the core layer, which was then coated with a shell layer containing a gamma-ray shielding agent. When exposed to neutron radiation, the neutrons 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 absorption of neutrons by the gadolinium in the core layer were 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, thereby achieving the effect of simultaneously protecting against neutrons and gamma-rays. Although the nano-protective fibers of Comparative Examples 2-3 can protect against neutrons and gamma rays in the environment, the secondary gamma rays generated by the neutron absorber gadolinium powder when absorbing neutrons can penetrate the fibers through the gaps where there is no gamma-ray shielding agent, making the fiber fabric unable to shield the secondary gamma rays well, thereby reducing the fabric's protective effect against gamma rays.

[0135] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0136] The above-described embodiments merely represent several implementation methods of the present application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims, and the specification may be used to interpret the content of the claims.

Claims

1. A nano protective fiber, comprising a core layer and a shell layer, wherein the core layer is fibrous, the shell layer is coaxially coated on the core layer, the core layer comprises a first polymer and a neutron absorber filled in the first polymer, the shell layer comprises a second polymer and a gamma-ray shielding agent filled in the second polymer, and the neutron absorber comprises nano gadolinium oxide powder.

2. The nano protective fiber according to claim 1, wherein: The nano protective fiber meets at least one of the following conditions: (1) The diameter of the core layer is 100nm-200nm; (2) The thickness of the shell layer is 100nm-200nm; (3) The diameter of the nano protective fiber is 300-600nm.

3. The nano protective fiber according to any one of claims 1 to 2, wherein: The nano protective fiber meets at least one of the following conditions: (1) The particle size of the neutron absorber is 10nm-50nm; (2) The particle size of the gamma-ray shielding agent is 10nm-50nm.

4. The nano protective fiber according to any one of claims 1 to 3, wherein: The gamma-ray shielding agent is selected from at least one of nano-tungsten powder, nano-tantalum powder and nano-bismuth powder.

5. The nano protective fiber according to any one of claims 1 to 4, wherein: The nano protective fiber meets at least one of the following conditions: (1) the first polymer is selected from at least one of PVDF, TPU and PLA; (2) The second polymer is selected from at least one of TPU and PVDF.

6. The method for preparing the nano protective fiber according to any one of claims 1 to 5, comprising the following steps: Adding a core layer spinning solution and a shell layer spinning solution to the inner cavity and the outer cavity of a coaxial electrospinning device respectively, and performing electrospinning to obtain a nano protective fiber; the core layer spinning solution comprises a first polymer, a neutron absorber and a first solvent, the first polymer is dissolved in the first solvent, the neutron absorber is dispersed in the first solvent, and the shell layer spinning solution comprises a second polymer, a gamma-ray shielding agent and a second solvent, the second polymer is dissolved in the second solvent, and the gamma-ray shielding agent is dispersed in the second solvent; The neutron absorber includes nano-gadolinium oxide powder.

7. The preparation method according to claim 6, wherein The preparation method satisfies at least one of the following conditions: (1) In the core layer spinning solution, the first polymer comprises 5% to 20%, the first solvent comprises 75% to 94% and the neutron absorber comprises 1% to 5% by weight; (2) The shell spinning solution comprises, by weight percentage, 5%-20% of the second polymer, 75%-94% of the second solvent and 1%-5% of the gamma-ray shielding agent.

8. The preparation method according to any one of claims 6 to 7, wherein: The preparation method satisfies at least one of the following conditions: (1) the first solvent is selected from at least one of chloroform and NN-dimethylformamide; (2) The second solvent is NN-dimethylformamide.

9. The preparation method according to claim 8, wherein The first solvent is chloroform and NN-dimethylformamide in a volume ratio of 1:(3-8).

10. The preparation method according to any one of claims 6 to 9, wherein: The process parameters of the electrospinning satisfy at least one of the following conditions: (1) The liquid supply rate of the core layer spinning solution is 0.1mL / min-2mL / min; (2) The liquid supply rate of the shell spinning solution is 0.1 mL / min-4 mL / min; (3) The voltage of the electrospinning is 18 kV-30 kV; (4) The spinning distance of the electrospinning is 15 cm-20 cm; (5) The receiver speed of the electrospinning is 120r / min-160r / min.

11. The preparation method according to claim 10, wherein: The ratio of the liquid supply speed of the core layer spinning solution to the liquid supply speed of the shell layer spinning solution is 1:(1-2).

12. Use of the nano protective fiber according to any one of claims 1 to 5 in the preparation of protective products.

13. A protective product comprising the protective nanofiber according to any one of claims 1 to 5.

14. The protective article of claim 13, wherein: The protective product comprises a fabric, and the fabric comprises the nano protective fiber according to any one of claims 1-5.

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