A nano B / NC / F 2602 Double-layer energetic fiber and preparation method thereof

Abstract

The present invention discloses a nano B / NC / F 2602 The double-layer energetic fiber and its preparation method belong to the field of nano-boron powder modification, comprising the following steps: (1) preparing a core solution: adding nano-boron powder and NC into a solvent to prepare a core solution; (2) preparing a shell solution: adding F 2602 Add to the solvent to prepare a shell solution; (3) Electrospinning: After extracting the core solution and the shell solution with syringes, the extracted syringes are placed in syringe pumps respectively. The two syringes are connected by a coaxial needle, which is connected to a voltage generator. The product is received by a receiving device under certain parameters. After drying, a double-layer energetic fiber can be obtained. The present invention can further improve the dispersion uniformity of nano-boron particles in the fiber, increase the contact area between the boron powder and the air during the reaction, further deepen the reaction degree of the boron powder, and release energy more thoroughly, which can be effectively applied to the fields of explosives and propellants.

Description

Technical Field

[0001] The present invention belongs to the field of nano boron powder modification, and specifically relates to a nano B / NC / F 2602 Double-layer energetic fiber and preparation method thereof. Technical Background

[0002] Currently, energetic materials are being incorporated extensively into explosives and propellants, and are widely considered a key component of the defense industry. Nanoenergetic materials, a subset of these materials, possess novel physical and chemical properties, high energy release rates, and combustion efficiencies that distinguish them from traditional energetic materials, and have garnered widespread attention both domestically and internationally. Among newly developed nanocomposites, there is significant interest in controlling the composition and morphology of the composites to optimize and enhance energy output. Nanocomposite fibers exhibit excellent mechanical integrity, and their combustion behavior can be tuned by adjusting the nanoparticle content in the core layer. Furthermore, coating nanoparticles effectively prevents agglomeration and poor dispersion due to their high surface energy.

[0003] Electrospinning is a common method for preparing nanocomposite fibers. It is simple, efficient and convenient. In China, nitrocellulose (NC) is often used as the matrix material for nanocomposite fibers. Coaxial electrospinning is one of the common electrospinning methods. This method is developed on the basis of mixed electrospinning. Coaxial electrospinning can simultaneously load different raw materials into the core-shell fiber, and the inner fiber can be protected by the outer fiber. At the same time, due to the different melting points of the core-shell two layers of raw materials, this structure can also be used to achieve sequential control and controllable combustion of substances.

[0004] The combustion performance of nano-boron powder is relatively good, but its surface is easily oxidized. At the same time, due to its high surface energy, it is easy to agglomerate, resulting in incomplete combustion and incomplete energy release. Therefore, the precursor solution of nB / NC is prepared as the core solution, which will improve the dispersion performance of nano-boron powder and prepare a certain mass fraction of F 2602 The solution was used as the shell solution and the nB / NC / F was prepared by coaxial electrospinning technology. 2602 Double-layer nanofibers will open up new avenues for the practical use of nanoboron, and the core idea of ​​this approach is to use optimized nanostructures to achieve higher energy output.

[0005] Chinese patent CN 114105721 A uses a solvent evaporation method to coat the surface of boron nanoparticles with ethylenediamine. This uniform coating of ethylenediamine prevents oxidation of the nano-boron particles. Since the organic coating has a low ignition point, the gases generated after combustion help break down the boron oxide layer, improving the ignition and combustion performance of the boron particles. However, the composite particles coated with ethylenediamine exhibit an overall granular appearance. Due to the residual organic solvent surrounding the particles, the nano-boron particles cling together, which can affect combustion performance.

[0006] Chinese patent CN 114085119 B utilizes conventional vacuum rotary evaporation to coat perfluoroalkanoic acid onto the surface of micro-nano boron fuel. This method provides a micro-nano boron fuel surface-passivated with perfluoroalkanoic acid. This method simplifies the preparation process, improves combustion efficiency, and enables more complete energy release. It can be used in mixed explosives or solid propellants at specific proportions to significantly increase the energy density of composite energetic materials. However, the introduction of the acid can lead to poor long-term storage stability of the energetic material, making it unsuitable as a primary source of oxidizing elements in composite energetic materials. Therefore, the large-scale application of perfluoroalkanoic acid in energetic materials requires extensive experimental verification. Summary of the Invention

[0007] The purpose of the present invention is to provide a nano B / NC / F 2602 The double-layer energetic fiber and the preparation method thereof are simple, efficient and convenient, can release energy more thoroughly, and can be effectively applied in the fields of explosives and propellants.

[0008] The object of the present invention is achieved through the following technical solutions:

[0009] The present invention provides a nano B / NC / F 2602 The preparation method of the double-layer energetic fiber comprises the following steps:

[0010] (1) Preparation of core solution: Adding nano-boron powder and NC into solvent to prepare core solution;

[0011] (2) Prepare the shell solution: 2602 Add to the solvent to prepare a shell solution;

[0012] (3) Electrospinning: After extracting the core solution and the shell solution with a syringe, the extracted syringes are placed in the injection pump respectively. The two syringes are connected by a coaxial needle, and the needle is connected to the voltage generator. The product is received by a receiving device covered with tin foil or aluminum foil at a certain voltage, a certain injection rate and a certain distance. After drying, a double-layer energetic fiber can be obtained.

[0013] Furthermore, in step (1), the solvent is acetone and ethanol in a volume ratio of 9:1.

[0014] Furthermore, in step (1), the mass ratio of the nano-boron powder to the NC is 1:10, and the mass concentration of the nano-boron powder in the core solution is 10-20 wt%.

[0015] Furthermore, the solvent is acetone.

[0016] Furthermore, the mass concentration of the F2602 is 5-15wt%.

[0017] Furthermore, the syringe is a disposable medical syringe, and the needle is a coaxial all-metal needle.

[0018] Furthermore, the certain voltage is a working voltage of 14-22 kV, the certain injection rate is a core flow rate of 3-5 ml·h-1 and a shell flow rate of 5-10 ml·h-1, and the certain distance is a distance between the needle and the receiving device of 12-20 cm.

[0019] The present invention also provides a nano B / NC / F2602 double-layer energetic fiber prepared by using the above-mentioned method for preparing the nano B / NC / F2602 double-layer energetic fiber.

[0020] The present invention also provides a nano B / NC / F 2602 Application of double-layer energetic fibers in explosives and propellants.

[0021] The beneficial effects of the present invention are:

[0022] (1) Compared with traditional coating methods, it is simple, efficient and convenient.

[0023] (2) The morphology of energetic fibers can be controlled by adjusting the parameters of electrospinning.

[0024] (3) It can prevent the surface oxidation of boron powder during storage. The formed oxides react with water in the air to generate boric acid, which makes the nano boron powder agglomerate more seriously, resulting in problems such as difficulty in ignition and incomplete energy release during use of the boron powder.

[0025] (4) The dispersion uniformity of nano-boron particles in the fiber can be further improved, so that the contact area between the boron powder and the air is larger during the reaction, the reaction degree of the boron powder continues to deepen, and the energy release is more thorough, which can be effectively applied in the field of explosives and propellants. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the overall structure of the device in Example 1;

[0027] Figure 2 The nano B / NC / F in Example 2 2602SEM images of double-layer energetic fibers;

[0028] Figure 3 The nano B / NC / F in Example 3 2602 XPS spectrum of double-layer energetic fibers;

[0029] Figure 4 The nano B / NC / F in Example 4 2602 IR spectrum of double-layer energetic fiber;

[0030] Figure 5 For the nano B / NC / F in Example 5 2602 DSC spectrum of double-layer energetic fiber. DETAILED DESCRIPTION

[0031] The following experimental examples and embodiments are intended to further illustrate the present invention, but are not intended to limit the present invention.

[0032] Example 1

[0033] This embodiment involves the preparation of a nano B / NC / F 2602 The core mass concentration of the double-layer energetic fiber is 10wt%, wherein the overall structure diagram of this embodiment is as shown in FIG. Figure 1 shown.

[0034] (1) NC was added to a solution consisting of acetone and ethanol to obtain an NC solution, wherein the volume ratio of acetone to ethanol was 9:1, and then nano-boron powder was added to the NC solution so that the mass ratio of nano-boron powder to the raw material NC was 1:10. The solution was ultrasonicated for 30 minutes, stirred at 42.5°C for 4 hours, and then allowed to stand for 8 hours to obtain a core solution containing a boron powder with a mass concentration of 10 wt%.

[0035] (2) F 2602 Add to acetone solvent to obtain F 2602 The mass concentration of the shell solution is 15wt%.

[0036] (3) After extracting the core solution with a disposable medical syringe, place the disposable medical syringe in the syringe pump. After extracting the shell solution with another disposable medical syringe, place the disposable medical syringe in the syringe pump as well. Connect the two disposable medical syringes (wherein the disposable syringe specifications are 5, 10, and 20 ml) through a coaxial needle. The needle is a coaxial all-metal needle with an inner diameter of 0.84 mm and an outer diameter of 1.27 mm (wherein the needle specifications are 18G / 14G, 19G / 15G, and 22G / 17G). The needle is connected to a voltage generator, and the working voltage is 16 kV (14-22 kV is acceptable) and the core flow rate is 3.6 ml·h. -1 (3-5ml / h), shell flow rate 6ml·h-1 Under the conditions of a flow rate of 5-10 ml / h and an ambient temperature of 20-29°C, coaxial electrospinning is carried out, and a receiving device is covered with tin foil or aluminum foil at a distance of 12 cm (12-20 cm) between the needle and the collector to receive the product. After drying, a double-layer energetic fiber can be obtained.

[0037] Example 2

[0038] This embodiment involves the preparation of a nano B / NC / F 2602 Double-layer energetic fiber with a core mass concentration of 20wt%.

[0039] The only difference between the embodiment 1 and the embodiment 1 is that the mass concentration of boron powder in the core solution is 20 wt%. 2602 The SEM images of the double-layer energetic fibers are shown in Figure 2. Figure 2 shown.

[0040] Figure 2 The SEM images show that the fiber surface of the double-layer energetic fiber prepared by the present invention is relatively smooth, without obvious defects such as shrinkage holes and gaps, which is conducive to the thermal decomposition performance of the fiber.

[0041] Example 3

[0042] This embodiment involves the preparation of a nano B / NC / F 2602 Double-layer energetic fiber with a shell mass concentration of 5wt%.

[0043] The only difference between this embodiment and Example 1 is that the concentration of boron powder in the core solution is 15 wt % and the concentration of F in the shell solution is 15 wt %. 2602 The mass concentration of the prepared nano B / NC / F 2602 The XPS spectrum of the double-layer energetic fiber is as follows Figure 3 shown.

[0044] Figure 3 The XPS spectrum shows that in the double-layer energetic fiber prepared in this example, the B1s and N1s peaks are the peaks unique to boron powder and nitrocellulose in the sample, respectively. However, they are difficult to detect in the sample, which basically confirms that nB / NC is F 2602 The coating was complete, and no other characteristic peaks were detected in the entire sample, indicating that no other impurities were introduced into the sample.

[0045] Example 4

[0046] This embodiment involves the preparation of a nano B / NC / F 2602 Double-layer energetic fiber with a shell mass concentration of 10wt%.

[0047] The only difference between this embodiment and Example 1 is that the concentration of boron powder in the core solution is 15 wt % and the concentration of F in the shell solution is 15 wt %. 2602 The mass concentration of the prepared nano B / NC / F 2602 The IR spectrum of the double-layer energetic fiber is as follows Figure 4 shown.

[0048] Figure 4 The IR spectrum shows that the characteristic peaks of the double-layer energetic fiber prepared by the present invention are similar to those of the raw materials nano-boron, NC, F 2602 The characteristic peaks of NC and F overlap with each other, and no chemical reaction occurs between the raw materials during the electrospinning process. 2602 They still exist in their own physical forms.

[0049] Example 5

[0050] This embodiment involves the preparation of a nano B / NC / F 2602 Double-layer energetic fiber with a shell mass concentration of 15wt%.

[0051] The only difference between this embodiment and Example 1 is that the concentration of boron powder in the core solution is 15 wt % and the concentration of F in the shell solution is 15 wt %. 2602 The mass concentration of the prepared nano B / NC / F 2602 The DSC spectrum of the double-layer energetic fiber is as follows Figure 5 shown. Figure 5 The DSC spectrum shows that in the double-layer energetic fiber prepared in this embodiment, after spinning, NC and F 2602 The decomposition heat release increases the temperature around the boron powder. At the same time, the boron powder has better dispersion after spinning and the contact area with air is wider during the reaction, which makes boron more 2602 The exothermic peak temperature of the boron powder was 41°C lower than that of the boron powder alone.

[0052] The performance of the product prepared in Example 5 was tested, and the results are listed in Table 1, where the sample numbers -1 and -2 refer to two tests of the same sample under the same conditions in order to reduce the error caused by a single experiment.

[0053] Table 1 Peak pressure and pressure increase rate of constant volume combustion of two samples

[0054]

[0055]

[0056] The constant volume combustion used in the present invention is usually used to study the ability of energetic materials to produce gas by combustion or explosion. 2602 The double layer samples and the ones without F2602 The single-layer sample was ignited to study the influence of the single and double-layer structures on the combustion performance. Generally, during the combustion process, gas products are continuously generated, causing the pressure in the combustion chamber to rise rapidly to a peak value, and the pressurization rate is determined by calculating the slope between 10% and 90% of the peak pressure (Pmax).

[0057] From Table 1 above, we can see that: F 2602 The addition of the outer layer structure has a positive effect on the combustion performance. Compared with the single-layer structure, the double-layer structure has a more obvious improvement in combustion performance, which makes the energy release of nano-boron powder more thorough and can meet the combustion requirements of solid propellants to a certain extent.

[0058] The present invention uses acetone and ethanol solutions as solvents, which can fully dissolve the drugs used. The coaxial electrospinning method is used to propel the precursor solution through an injection pump. Under the action of the electric field, the droplet at the needle tip changes from a spherical shape to a conical shape (i.e., a "Taylor cone"), and extends from the tip of the cone to obtain fiber filaments, which reach a receiving device under the action of Coulomb force to form a fiber product. This method is efficient, low-cost, and simple, and can replace the solvent evaporation method and the traditional vacuum rotary evaporation method for coating nanomaterials. The energetic fiber prepared by the preparation method provided by the present invention has a good morphology, improves the combustion performance and energy release rate of nano boron powder, can meet the requirements of modern solid propellants to a certain extent, and provides a new method and idea for reducing the agglomeration of nano energetic materials and ultimately improving the reaction activity.

[0059] The present invention utilizes a coaxial electrospinning method, a simple and easy-to-use process. By adjusting the coaxial electrospinning parameters, the energetic fiber morphology can be controlled. Compared to nano-boron powder coated by solvent evaporation or conventional vacuum rotary evaporation, the double-layer energetic fibers produced by this method have little effect on the particle size of the nano-boron powder, resulting in a more even dispersion of the nano-boron powder within the nanofibers and a relatively uniform fiber thickness. This effectively avoids the problems encountered in conventional coating methods, such as the easy agglomeration of nano-boron powder and its poor long-term storage stability, which can lead to problems such as difficulty in ignition and incomplete energy release during use.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be covered by the scope of the claims of the present invention.

Claims

1. A nano B / NC / F 2602 The method for preparing a double-layer energetic fiber is characterized in that: The following steps are included: (1) Preparing the core solution: Adding nano-boron powder and NC into the solvent to prepare the core solution; (2) Prepare the shell solution: 2602 Add to the solvent to prepare a shell solution; (3) Electrospinning: After extracting the core solution and the shell solution with syringes, the extracted syringes were placed in the syringe pumps respectively. The two syringes were connected by a coaxial needle, which was connected to a voltage generator. The working voltage was 14-22 kV and the core solution flow rate was 3-5 ml·h. -1 , Shell solution flow rate 5-10ml·h -1 The product is received by a receiving device covered with tin foil or aluminum foil under the condition that the distance between the needle and the receiving device is 12-20 cm, and a double-layer energetic fiber can be obtained after drying; In step (1), the solvent is acetone and ethanol in a volume ratio of 9:1; In step (1), the mass ratio of the nano-boron powder to the NC is 1:10, and the mass concentration of the nano-boron powder in the core solution is 10-20wt%; In step (2), the solvent is acetone; In step (2), the F 2602 The mass concentration is 5-15wt%.

2. Nano B / NC / F according to claim 1 2602 The method for preparing a double-layer energetic fiber is characterized in that: In step (3), the syringe is a disposable medical syringe, and the needle is a coaxial all-metal needle.

3. A method of using the nano B / NC / F according to any one of claims 1-2 2602 Nano B / NC / F prepared by the preparation method of double-layer energetic fiber 2602 Double-layer energetic fiber.

4. A nano B / NC / F as claimed in claim 3 2602 Application of double-layer energetic fibers in the field of explosives or propellants.

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